The effect of collagen fibril orientation on the biphasic mechanics of articular cartilage

The highly inhomogeneous distribution of collagen fibrils may have important effects on the biphasic mechanics of articular cartilage. However, the effect of the inhomogeneity of collagen fibrils has mainly been investigated using simplified three-layered models, which may have underestimated the effect of collagen fibrils by neglecting their realistic orientation. The aim of this study was to investigate the effect of the realistic orientation of collagen fibrils on the biphasic mechanics of articular cartilage. Five biphasic material models, each of which included a different level of complexity of fibril reinforcement, were solved using two different finite element software packages (Abaqus and FEBio). Model 1 considered the realistic orientation of fibrils, which was derived from diffusion tensor magnetic resonance images. The simplified three-layered orientation was used for Model 2. Models 3–5 were three control models. The realistic collagen orientations obtained in this study were consistent with the literature. Results from the two finite element implementations were in agreement for each of the conditions modelled. The comparison between the control models confirmed some functions of collagen fibrils. The comparison between Models 1 and 2 showed that the widely-used three-layered inhomogeneous model can produce similar fluid load support to the model including the realistic fibril orientation; however, an accurate prediction of the other mechanical parameters requires the inclusion of the realistic orientation of collagen fibrils.</p

The role of peptides in bone healing and regeneration: A systematic review

Background: Bone tissue engineering and the research surrounding peptides has expanded significantly over the last few decades. Several peptides have been shown to support and stimulate the bone healing response and have been proposed as therapeutic vehicles for clinical use. The aim of this comprehensive review is to present the clinical and experimental studies analysing the potential role of peptides for bone healing and bone regeneration. Methods: A systematic review according to PRISMA guidelines was conducted. Articles presenting peptides capable of exerting an upregulatory effect on osteoprogenitor cells and bone healing were included in the study. Results: Based on the available literature, a significant amount of experimental in vitro and in vivo evidence exists. Several peptides were found to upregulate the bone healing response in experimental models and could act as potential candidates for future clinical applications. However, from the available peptides that reached the level of clinical trials, the presented results are limited. Conclusion: Further research is desirable to shed more light into the processes governing the osteoprogenitor cellular responses. With further advances in the field of biomimetic materials and scaffolds, new treatment modalities for bone repair will emerge

Computational modelling of fluid load support in articular cartilage

Natural articular cartilage is known to be an excellent bearing material with very low friction coefficient and wear rate. Theoretical and experimental studies have demonstrated that the interstitial fluid of cartilage is pressurized considerably under loading to support the applied load, leading to the low friction coefficient. In this process, collagen fibrils play a vital role to resist the lateral expansion of cartilage and enhance the pressurization. The proportion of the total load supported by fluid pressurization in cartilage, called the fluid load support, is therefore an important parameter in biotribology and determined as the main aspect of this thesis. Fibril-reinforced cartilage models were set up to account for the high pressurization of interstitial fluid. However, the orientation of collagen fibrils were idealized or simplified; and the models implementing realistic fibril orientation derived from DT-MRI data did not include viscous effects in both the solid matrix and the fibril. This study overcome the limitation of previous models and the major finding were: • The peak value of fluid load support in both 2D and 3D fibrilreinforced models implementing DT-MRI data was increased to greater than 90% from around 60% in the isotropic poroelastic model, due to the reinforcement by collagen fibril. • The implementation of the realistic fibril orientation in the 3D fibrilreinforced model increased the value of peak pore pressure (by 15%) compared to the uniformly reinforced model while the peak contact pressure was 4.3% lower, making the peak value of fluid load support increase from 80.4% to 96.7%. • The rationality to define the principal eigenvector as orientation of the corresponding primary collagen fibril in the fibril-reinforced models was verified by the related results. • The feasibility and reliability of the methodologies to implement DTMRI data to the fibril-reinforced models were both confirmed in the modelling process

Cuidados paliativos para imigrantes chineses na Nova Zelândia: experiências e percepções

Over the past several decades, palliative care has seen tremendous development in Western countries, but there is still inadequate access to palliative care among non-dominant ethnocultural groups. The Chinese have been the largest immigrant group in New Zealand since the 19th century(1). They have unique beliefs and practices around illness, death, dying and filial piety(2). These differ greatly from those in Western cultures and have notable implications for hospice palliative care planning and provision. However, immigrant Chinese community remains a relatively marginalised and under-researched group in palliative care(3-5). This results in limited knowledge about its culture and people among health professionals, as well as the lack of experience in providing terminal care to Chinese immigrants. Through the introduction of New Zealand Palliative Care Strategy and the analysis of Chinese immigrants’ difficulties and preferences for palliative care, this aims to increase understanding of how cultural values of Chinese affect their acceptance and decision-making with respect to palliative care so that for efficiently providing palliative care to this ethnic minority group in New Zealand.En las últimas décadas, los cuidados paliativos han experimentado un enorme desarrollo en los países occidentales, pero el acceso a los mismos sigue siendo insuficiente entre los grupos etnoculturales no dominantes. Los chinos son el mayor grupo de inmigrantes en Nueva Zelanda desde el siglo XIX(1). Tienen creencias y prácticas únicas en torno a la enfermedad, la muerte, el morir y la piedad filial(2). Éstas difieren en gran medida de las de las culturas occidentales y tienen notables implicaciones para la planificación y prestación de cuidados paliativos en los hospicios. Sin embargo, la comunidad china inmigrante sigue siendo un grupo relativamente marginado y poco investigado en el ámbito de los cuidados paliativos(3-5). Esto se traduce en un conocimiento limitado sobre su cultura y su población entre los profesionales sanitarios, así como en la falta de experiencia en la prestación de cuidados terminales a los inmigrantes chinos. A través de la introducción de la Estrategia de Cuidados Paliativos de Nueva Zelanda y el análisis de las dificultades y preferencias de los inmigrantes chinos en materia de cuidados paliativos, este ensayo pretende aumentar la comprensión de cómo los valores culturales de los chinos afectan a su aceptación y la toma de decisiones con respecto a los cuidados paliativos para que para proporcionar de manera eficiente los cuidados paliativos a este grupo étnico minoritario en Nueva Zelanda.Nas últimas décadas, os cuidados paliativos tem experimentado um enorme desenvolvimento nos países ocidentais mas ainda há acesso inadequado a cuidados paliativos entre grupos étnico-culturais não dominantes. Os chineses tem sido o maior grupo de imigrantes na Nova Zelândia desde o século XIX(1). Eles tem crenças e práticas singulares em torno de doença, morte, morrer e devoção filial(2). Isso difere grandemente das culturas ocidentais e tem implicações notáveis no planejamento e fornecimento de cuidados paliativos em lares de idosos. Entretanto, a comunidade de imigrantes chineses permanece sendo um grupo relativamente marginalizado e sub-investigado no que diz respeito a cuidados paliativos(3-5). Isso resulta em conhecimento limitado sobre sua cultura e povo entre profissionais da saúde, bem como na falta de experiência em fornecer cuidados terminais a imigrantes chineses. Através da introdução da Estratégia de Cuidados Paliativos da Nova Zelândia e a análise das dificuldades e preferências de imigrantes chineses para cuidados paliativos, esse estudo tente aumentar a compreensão de como valores culturais de chineses afetam sua aceitação e tomada de decisão a respeito de cuidados paliativos, de maneira a eficientemente fornecer cuidados paliativos a esse grupo étnico minoritário na Nova Zelândia

Effects of Process Parameters on the Thickness Uniformity in Two-Point Incremental Forming (TPIF) with a Positive Die for an Irregular Stepped Part

Incremental sheet forming (ISF) is a novel flexible forming technology with advantages, such as a low forming force, low-energy-consuming equipment, and good forming performance. The lack of available information about the formability of the two-point incremental forming (TPIF) process makes it limited for practical applications. Taking an irregular stepped part as the target part, the effects of process parameters on the thickness uniformity when using TPIF with a positive die for AA1060 aluminum alloy sheets were investigated. First, the set of optimal parameters regarding the diameter of the tool head, feed rate, and the step size were obtained through orthogonal experiments. Furthermore, the optimal parameter set of the number of forming passes, the direction of movement of the forming tool, and the forming angle was determined and the optimal forming result was numerically and experimentally verified. This demonstrated that the parameters affecting the thickness uniformity of the irregular stepped parts were, in descending order, the diameter of the forming tool, the feed rate, and the step size, with corresponding optimal values of 12 mm, 15,000 mm/min, and 0.4 mm, respectively. With an increase of the number of passes and a decrease of the forming angle between adjacent passes, and adopting an alternating clockwise and counterclockwise toolpath, the thickness uniformity of the formed parts was effectively improved