The Role of Cement in the Long Term Performance and Premature Failure of Charnley Low Friction Arthroplasties

1986 ◽  
Vol 15 (1) ◽  
pp. 19-22 ◽  
Author(s):  
G H Isaac ◽  
J R Atkinson ◽  
D Dowson ◽  
B M Wroblewski
Keyword(s):  
Premature Failure ◽  
Hip Prostheses ◽  
Acrylic Cement ◽  
A Value ◽  
Articulating Surface ◽  
Long Term Performance ◽  
Term Performance

A number of polyethylene acetabular cups (59) and femoral stems (38) of Charnley hip prostheses were obtained following revision surgery and examined by scanning electron microscopy. In many cases, acrylic cement particles were embedded in the articulating surface of the cups. These particles caused surface pitting. The appearance of the articulating surfaces suggested that some cement had been present from the time of arthroplasty. In other cups there was evidence of cement ingress during the service life. Failure to use sufficient cement at arthroplasty resulted in cavities on the backs of the cups. Many femoral heads had become scratched in vivo, the surface roughness increasing from an initial value less than 0.02 μm Ra to a value on removal of 0.07 μm Ra. The increased roughness increases the amount of wear in the polyethylene sockets. Laboratory tests show that retrieved acrylic cement particles will scratch stainless steel, and it is our conclusion that entrapped cement will damage both components of the prosthesis and may cause premature failure.

scholarly journals Alkali-activated materials: the role of molecular-scale research and lessons from the energy transition to combat climate change

2020 ◽  
Vol 4 ◽  
pp. 110-121 ◽  
Author(s):  
Claire White
Keyword(s):  
Portland Cement ◽  
Financial Incentives ◽  
Field Performance ◽  
Energy Transition ◽  
Combat Climate Change ◽  
Long Term Performance ◽  
Term Performance ◽  
Alkali Activated

Alternative (i.e., non-Portland) cements, such as alkali-activated materials, have gained significant interest from the scientific community due to their proven CO2 savings compared with Portland cement together with known short-term performance properties. However, the concrete industry remains dominated by Portland cement-based concrete. This Letter explores the technical and non-technical hurdles preventing implementation of an alternative cement, such as alkali-activated materials, in the concrete industry and discusses how these hurdles can be overcome. Specifically, it is shown that certain technical hurdles, such as a lack of understanding how certain additives affect setting of alkali-activated materials (and Portland cement) and the absence of long-term in-field performance data of these sustainable cements, can be mitigated via the use of key molecular- and nano-scale experimental techniques to elucidate dominant material characteristics, including those that control long-term performance. In the second part of this Letter the concrete industry is compared and contrasted with the electricity generation industry, and specifically the transition from one dominant technology (i.e., coal) to a diverse array of energy sources including renewables. It is concluded that financial incentives and public advocacy (akin to advocacy for renewables in the energy sector) would significantly enhance uptake of alternative cements in the concrete industry.

Does the Bargaining Power of Vertical Parties Improve or Worsen the Effect of Family Influence on Long-Term Performance?

2020 ◽  
pp. 154-184
Author(s):  
Rubén Martínez-Alonso ◽  
María J. Martínez-Romero ◽  
Julio Diéguez-Soto ◽  
Alfonso A. Rojo-Ramírez
Keyword(s):  
Environmental Factor ◽  
Bargaining Power ◽  
Manufacturing Firms ◽  
Family Influence ◽  
Negative Effect ◽  
Long Term Performance ◽  
Term Performance ◽  
Moderating Role

Grounding in the socioemotional wealth approach, this chapter explores the effect of family influence on long-term performance. Moreover, this study also examines the moderating role of the bargaining power of vertical parties, namely supplier (SBP) and customer (CBP) bargaining power, on the preceding relationship. By utilising a panel dataset of 3,118 observations of Spanish private manufacturing firms in the 2007–2016 period, the chapter finds that family influence negatively impacts long-term performance. The findings also reveal that CBP mitigates the negative effect of family influence on long-term performance. In this light, CBP is found to be a potential environmental factor that enables family influenced firms enhancing their long-term performance.

Longevity of Twelve Geomembranes in Chlorinated Water

2020 ◽  
Author(s):  
Mohamed S. Morsy ◽  
R. Kerry Rowe ◽  
Fady B. Abdelaal
Keyword(s):  
Induction Time ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Light Stabilizer ◽  
Long Term Performance ◽  
Term Performance ◽  
Master Batch

The long-term performance of geomembranes with twelve different resin/antioxidant master-batch combinations, including eight HDPE, three linear low density polyethylene (LLDPE), and one blended polyolefin (BPO) base resins, is investigated. Results are reported for immersion tests in chlorinated water (0.5 ppm) for 35 months at 85oC. The degradation trends show that the choice of resin type played a key role in the longevity of the geomembranes but also that some hindered amine light stabilizer (HALS) packages contributed to better resistance to degradation in chlorinated water. The results show that the specific antioxidant package is more important than the initial oxidative induction time (OIT) in terms of long-term performance. Finally, it is shown that while increased thickness may be beneficial, a more resistant resin or antioxidant/stabilizes package can be more effective than increasing thickness in improving geomembrane performance in chlorinated water. The conclusion regarding the beneficial role of HALS is specific to chlorinated water and generally is not true in other cases of submerged or buried geomembranes.

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