Resistance of a novel ceramic acetabular cup to critical impact loads

A novel thin-walled direct-to-bone fixation ceramic cup was tested under critical impact loads simulating lateral fall and car crash scenarios. Three sizes of BIOLOX delta ceramic cups (total hip replacement cup with bearing diameter of 32 mm and two hip resurfacing cups with bearing diameters of 40 and 64mm) were implanted into reamed Sawbones blocks representing acetabulae. Three cups of each size were fully supported by the block and three were implanted with 15° of the cup’s outer diameter unsupported by the block. All testing was conducted with the corresponding bearing diameter heads lateralised by approximately 1 mm to represent worst case subluxed hips and all then subjected to test, replicating a lateral fall impact followed by a car crash impact. All cups passed lateral fall conditions without visible damage, although some movement of the cups was measured and damage to the blocks was observed. Five out of six of each cup size survived the car crash impacts with one fracture per size. In all cases, this was in the fully supported condition representing the highest cup inclination angle. The car crash impact force was equivalent to that reported to fracture the acetabulum and in all simulated cases, the Sawbones block showed signs of damage. Survival of five cups per size suggests the pelvis is much more likely to fracture before the cup. The ability of the cups to withstand these critical impact forces indicates they are unlikely to fracture in normal clinical use and should meet the more challenging demands of active patients likely to receive this device.

The effectiveness of the nitrification inhibitor dicyandiamide (DCD) for mitigating nitrogen leaching losses from a winter grazed forage crop on a free draining soil in northern Southland.

Evidence suggests that the wintering of stock on forage crops is a significant contributor to N losses from livestock farming. Losses are likely to be exacerbated if crops are grown on shallow free-draining soils types and grazed by dairy cattle. A three-year trial (December 2008 - November 2011) was conducted in northern Southland on a soil classified as having severe vulnerability for nutrient leaching to groundwater. Porous ceramic cups were installed under a brassica crop which was grazed by dairy cows in June each year and the leachate collected regularly for N analysis. The treatments evaluated were with and without a single application of DCD applied at the time of crop grazing. Concentrations of nitrate-N in drainage water ranged from 40 mg/L in May 2011. Concentrations of dissolved organic N (DON) also increased from a low initial value (

CÁPSULA POROSA: INTERFERÊNCIA NA AMOSTRA DA SOLUÇÃO DO SOLO E METODOLOGIA DE LAVAGEM

CÁPSULA POROSA: INTERFERÊNCIA NA AMOSTRA DA SOLUÇÃO DO SOLO E METODOLOGIA DE LAVAGEM Bruno F. F. Pereira,1; Tamara M. Gomes2; Sandra F. Nogueira3; Célia R. Montes3; Adolpho J. Melfi11Departamento de Ciência do Solo, Núcleo de Pesquisa em Geoquímica e Geofísica da Litosfera, Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba, SP, [email protected]úcleo de Pesquisa em Geoquímica e Geofísica da Litosfera, Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba, SP3Núcleo de Pesquisa em Geoquímica e Geofísica da Litosfera, CENA, Universidade de São Paulo, Piracicaba, SP 1 RESUMO As cápsulas porosas de cerâmica (CP) utilizadas para amostrar a solução do solo podem liberar íons na solução interferindo na concentração de determinados elementos nas amostras. Este trabalho tem como objetivos avaliar: (i) a dessorção de cátions interferentes pela CP (ii) a eficiência de uma metodologia de tratamento das CPs, visando minimizar a desorção de cátions. O experimento foi conduzido em laboratório. O delineamento experimental foi inteiramente casualizado contendo três tratamentos e três repetições. a) Lavagem externa da CP com água deionizada + lavagem em solução HCl (0,1 mol L-1) + 4 ciclos de água deionizada (HCl+A); b) Testemunha: sem lavagem da CP (S). As soluções resultantes foram comparadas com água deionizada (teste em branco - TB). Não foi observado a dessorção significativa de N, P, K, S, B, Cu, Fe, Mn, Zn e Al pelas CPs. Cálcio, Mg e Na foram dessorvidos pelas CPs nas seguintes concentrações; 6,73; 0,20 e 0,70 mg L-1, respectivamente, e interferiram significativamente na solução extraída quando comparados com a solução TB. Após o tratamento das CPs, a concentração destes elementos foram inferiores ao limite de detecção para Ca e Na e 0,01 mg L-1 para Mg, não diferindo significativamente da solução em branco. UNITERMOS: íons, limpeza de cápsula porosa, interferência, dessorção PEREIRA, B. F. F.; GOMES, T. M.; NOGUEIRA, S. F.; MONTES, C. R.; MELFI, A. J. INTERFERENCE OF CERAMIC POROUS CUP ON SOIL SOLUTION SAMPLES 2 ABSTRACT Ceramic porous cups (CP) used to soil solution sampling in situ can release ions on extracted solution interfering on the real concentration of some elements of the sample. The objectives of this study were to evaluate; (i) cation desorption by the CP and (ii) the efficiency of a new methodology of CPs treatment to decrease the cation desorption. The study was carried out in laboratory. The experimental design was completely randomized with two treatments and three replications; a) external washing of CP with deionized water + washing in HCl (0.1 mol L-1) solution + 4 washing cycles with deionized water (HCl+A); b) No washing of CP (S). The extracted solution from each treatment (HCl+A and S) was compared with deionized water (blank –TB). There was no significant desorption of N, P, K, S, B, Cu, Fe, Mn, Zn and Al by the CPs. Ca, Mg and Na were desorbed by CP and had the following concentrations: 6.73, 0.20 and 0.70 mg L-1 respectively. They interfered significantly on the extracted solution when compared with TB solution. After the CPs treatment, Ca and Na concentration on solution were below the limit of detection, and Mg concentration was 0.01 mg L-1, and there was no difference from the blank solution. KEYWORDS: ions, ceramic cups clean-up, interference, desorption

Assessment of vadose zone sampling methods for detection of preferential herbicide transport

Accurate soil water sampling is needed for monitoring of pesticide leaching through the vadose zone, especially in soils with significant preferential flowpaths. We assessed the effectiveness of wick and gravity pan lysimeters as well as ceramic cups (installed 45–60 cm deep) in strongly-structured silty clay loam (Hudson series) and weakly-structured fine sandy loam (Arkport series) soils. Simulated rainfall (10–14 cm in 4 d, approximately equal to a 10-yr, 24 h storm) was applied following concurrent application of agronomic rates (0.2 g m−2) of atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) and 2,4-D (2,4-dichloro-phenoxy-acetic acid) immediately following application of a chloride tracer (22–44 g m−2). Preferential flow mechanisms were observed in both soils, with herbicide and tracer mobility greater than would be predicted by uniform flow. Preferential flow was more dominant in the Hudson soil, with earlier breakthroughs observed. Mean wick and gravity pan sampler percolate concentrations at 60 cm depth ranged from 96 to 223 μg L−1 for atrazine and 54 to 78 μg L−1 for 2,4-D at the Hudson site, and from 7 to 22 μg L−1 for atrazine and 0.5 to 2.8 μg L−1 for 2,4-D at the Arkport site. Gravity and wick pan lysimeters had comparably good collection efficiencies at elevated soil moisture levels, whereas wick pan samplers performed better at lower moisture contents. Cup samplers performed poorly with wide variations in collections and solute concentrations.