The Effect of Reducing the Bone to Cast Distance in an Equine Transfixation Pin Cast: An Ex Vivo Biomechanical Study

Abstract Objective The aim of this study was to evaluate the effect of reducing the bone to cast distance on the resistance of the pin to cyclic loading in equine transfixation pin casts. Study Design Eleven pairs of cadaveric equine third metacarpal bones were prepared and one 6.3/8.0 mm transfixation pin was placed in standard fashion 10 mm proximal to the distal physeal scar into each bone. One metacarpus of each pair was tested with a distance of 10 mm (10 mm group) and the contralateral metacarpus with a distance of 20 mm (20 mm group) between the outer cortex of the bone and the fixation of the pin. Eight pairs were tested using a simplified test set-up in which the pins were fastened at both ends to polyoxymethylene-copolymer sleeves. The pins of the remaining three pairs of bones were incorporated into a fibreglass cast. All specimens were tested under cyclic loading until failure of the pin in axial compression. Results All pins failed uni- or bilaterally at clinically relevant load levels. Pins of the 10 mm group endured significantly (p < 0.05) higher load levels and total number of cycles until failure compared with the pins of the 20 mm group. Conclusion The distance between the bone surface and the cast at the location of pin insertion has a significant effect on resistance of the pins to cyclic loading. Therefore, the amount of padding applied underneath an equine transfixation pin cast can have an influence on the overall stability and durability of the construct.

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Problem of Pin Breakage in Equine Transfixation Pin Casting: Biomechanical Ex Vivo Testing of Four Different Pins

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0039-1678734 ◽

2019 ◽

Vol 32 (03) ◽

pp. 222-233

Author(s):

Sara Keller ◽

Sebastian Valet ◽

Ann Martens ◽

Bernhard Weisse ◽

Anton Fürst ◽

...

Keyword(s):

Cyclic Loading ◽

Ex Vivo ◽

Cyclic Fatigue ◽

Fatigue Behaviour ◽

Simplified Model ◽

Testing Conditions ◽

Metacarpal Bones ◽

Ex Vivo Testing ◽

Cycles To Failure ◽

Steinmann Pin

Objective The aim of this study was to evaluate cyclic fatigue behaviour of a new pin with a thread run-out design in comparison with three other types of pins commonly used for equine transfixation pin casting. Materials and Methods Twenty-four pairs of equine cadaveric third metacarpal bones (MC3) equipped with one transfixation pin placed horizontally in the distal metaphysis were tested using a simplified model, mimicking the biomechanical situation of equine transfixation pin casting. A 6.3/8.0-mm Imex Duraface pin with thread run-out design (ITROP) was compared with a 6.1-mm smooth Steinmann pin (SSP), a Securos 6.2-mm, positive-profile pin (SPPP) and an Imex 6.3-mm, positive-profile pin (IPPP) under cyclic loading until failure in axial compression of MC3. Results All pins broke at clinically relevant load levels and cycle numbers. The SSP endured significantly (p = 0.0025) more cycles before failure (mean: 48685) than the ITROP (mean 25889). No significant differences in cycles to failure were observed comparing the SPPP versus ITROP, and the IPPP versus ITROP, respectively. Clinical Significance A thread run-out design does not necessarily lead to higher resistance against pin breakage under cyclic loading conditions. The SSP was most resistant against cyclic failure in these testing conditions, even though it was associated with more lateromedial displacement and cortical wear-out. This could outweigh reported disadvantages of the SSP such as reduced resistance to axial extraction and pin loosening.

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Centrifuge test set up for installation and cyclic loading of suction caissons in sand

Physical Modelling in Geotechnics ◽

10.1201/noe0415415866.ch97 ◽

2006 ◽

Author(s):

M Randolph ◽

M Senders ◽

C Gaudin

Keyword(s):

Cyclic Loading ◽

Centrifuge Test ◽

Test Set ◽

Set Up ◽

Suction Caissons

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Aerosol generation through pars plana vitrectomy

British Journal of Ophthalmology ◽

10.1136/bjophthalmol-2020-317214 ◽

2020 ◽

pp. bjophthalmol-2020-317214

Author(s):

Hasan Naveed ◽

Fong May Chew ◽

Hanbin Lee ◽

Edward Hughes ◽

Mayank A Nanavaty

Keyword(s):

Pars Plana Vitrectomy ◽

Ex Vivo ◽

Dynamic Changes ◽

Aerosol Generation ◽

Significant Difference ◽

Optical Particle Counter ◽

Pars Plana ◽

23 Gauge ◽

Set Up ◽

Ex Vivo Study

PurposeTo assess whether pars plana vitrectomy (PPV) is an aerosol-generating procedure (AGP) in an ex vivo experimental model.MethodsIn this ex vivo study on 10 porcine eyes, optical particle counter was used to measure particles ≤10 μm using cumulative mode in the six in-built channels: 0.3 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm and 10 μm aerosols during PPV. Two parts of the study were as follows: (1) to assess the pre-experimental baseline aerosol count in the theatre environment where there are dynamic changes in temperature and humidity and (2) to measure aerosol generation with 23-gauge and 25-gauge set-up. For each porcine eye, five measurements were taken for each consecutive step in the experiment including pre-PPV, during PPV, fluid–air exchange (FAX) and venting using a flute with 23-gauge set-up and a chimney with 25-gauge set-up. Therefore, a total of 200 measurements were recorded.ResultsWith 23-gauge and 25-gauge PPV, there was no significant difference in aerosol generation in all six channels comparing pre-PPV versus PPV or pre-PPV versus FAX. Venting using flute with 23-gauge PPV showed significant reduction of aerosol ≤1 μm. Air venting using chimney with 25-gauge set-up showed no significant difference in aerosol of ≤1 μm. For cumulative aerosol counts of all particles measuring ≤5 μm, compared with pre-PPV, PPV or FAX, flute venting in 23-gauge set-up showed significant reduction unlike the same comparison for chimney venting in 25-gauge set-up.ConclusionPPV and its associate steps do not generate aerosols ≤10 μm with 23-gauge and 25-gauge set-ups.

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Investigation of Deformation Inhomogeneity and Low-Cycle Fatigue of a Polycrystalline Material

Applied Sciences ◽

10.3390/app11062673 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2673

Author(s):

Mu-Hang Zhang ◽

Xiao-Hong Shen ◽

Lei He ◽

Ke-Shi Zhang

Keyword(s):

Cyclic Loading ◽

Low Cycle Fatigue ◽

Strain Tensor ◽

Equivalent Strain ◽

Differential Entropy ◽

Strain Components ◽

Deformation Inhomogeneity ◽

Standard Deviations ◽

Number Of Cycles ◽

The Relationship

Considering the relationship between inhomogeneous plastic deformation and fatigue damage, deformation inhomogeneity evolution and fatigue failure of superalloy GH4169 under temperature 500 °C and macro tension compression cyclic loading are studied, by using crystal plasticity calculation associated with polycrystalline representative Voronoi volume element (RVE). Different statistical standard deviation and differential entropy of meso strain are used to measure the inhomogeneity of deformation, and the relationship between the inhomogeneity and strain cycle is explored by cyclic numerical simulation. It is found from the research that the standard deviations of each component of the strain tensor at the cyclic peak increase monotonically with the cyclic loading, and they are similar to each other. The differential entropy of each component of the strain tensor also increases with the number of cycles, and the law is similar. On this basis, the critical values determined by statistical standard deviations of the strain components and the equivalent strain, and that by differential entropy of strain components, are, respectively, used as fatigue criteria, then predict the fatigue–life curves of the material. The predictions are verified with reference to the measured results, and their deviations are proved to be in a reasonable range.

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Antagonism of Adherent Invasive E. coli LF82 With Human α-defensin 5 in the Follicle-associated Epithelium of Patients With Ileal Crohn’s Disease

Inflammatory Bowel Diseases ◽

10.1093/ibd/izaa315 ◽

2020 ◽

Author(s):

Lina Y Alkaissi ◽

Martin E Winberg ◽

Stéphanie DS Heil ◽

Staffan Haapaniemi ◽

Pär Myrelid ◽

...

Keyword(s):

Crohn’S Disease ◽

Crohn's Disease ◽

Ex Vivo ◽

Ussing Chambers ◽

E Coli ◽

Follicle Associated Epithelium ◽

Vitro Model ◽

Set Up

Abstract Background The first visible signs of Crohn’s disease (CD) are microscopic erosions over the follicle-associated epithelium (FAE). The aim of the study was to investigate the effects of human α-defensin 5 (HD5) on adherent-invasive Escherichia coli LF82 translocation and HD5 secretion after LF82 exposure in an in vitro model of human FAE and in human FAE ex vivo. Methods An in vitro FAE-model was set up by the coculture of Raji B cells and Caco-2-cl1 cells. Ileal FAE from patients with CD and controls were mounted in Ussing chambers. The effect of HD5 on LF82 translocation was studied by LF82 exposure to the cells or tissues with or without incubation with HD5. The HD5 secretion was measured in human FAE exposed to LF82 or Salmonella typhimurium. The HD5 levels were evaluated by immunofluorescence, immunoblotting, and ELISA. Results There was an increased LF82 translocation across the FAE-model compared with Caco-2-cl1 (P < 0.05). Incubation of cell/tissues with HD5 before LF82 exposure reduced bacterial passage in both models. Human FAE showed increased LF82 translocation in CD compared with controls and attenuated passage after incubation with sublethal HD5 in both CD and controls (P < 0.05). LF82 exposure resulted in a lower HD5 secretion in CD FAE compared with controls (P < 0.05), whereas Salmonella exposure caused equal secretion on CD and controls. There were significantly lower HD5 levels in CD tissues compared with controls. Conclusions Sublethal HD5 reduces the ability of LF82 to translocate through FAE. The HD5 is secreted less in CD in response to LF82, despite a normal response to Salmonella. This further implicates the integrated role of antimicrobial factors and barrier function in CD pathogenesis.

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Evaluation of malignant effusions using MR-based T1 mapping

Scientific Reports ◽

10.1038/s41598-021-86632-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

D. Kuetting ◽

J. Luetkens ◽

A. Faron ◽

A. Isaak ◽

U. Attenberger ◽

...

Keyword(s):

T1 Mapping ◽

Ex Vivo ◽

Diagnostic Yield ◽

Spin Echo ◽

Relaxation Times ◽

Inversion Recovery ◽

Malignant Effusions ◽

Mapping Techniques ◽

Set Up ◽

Post Hoc

AbstractOur aim was to investigate the diagnostic yield of rapid T1-mapping for the differentiation of malignant and non-malignant effusions in an ex-vivo set up. T1-mapping was performed with a fast modified Look-Locker inversion-recovery (MOLLI) acquisition and a combined turbo spin-echo and inversion-recovery sequence (TMIX) as reference. A total of 13 titrated albumin-solutions as well as 48 samples (29 ascites/pleural effusions from patients with malignancy; 19 from patients without malignancy) were examined. Samples were classified as malignant-positive histology, malignant-negative histology and non-malignant negative histology. In phantom analysis both mapping techniques correlated with albumin-content (MOLLI: r = − 0.97, TMIX: r = − 0.98). MOLLI T1 relaxation times were shorter in malignancy-positive histology fluids (2237 ± 137 ms) than in malignancy-negative histology fluids (2423 ± 357 ms) as well as than in non-malignant-negative histology fluids (2651 ± 139 ms); post hoc test for all intergroup comparisons: < 0.05. ROC analysis for differentiation between malignant and non-malignant effusions (malignant positive histology vs. all other) showed an (AUC) of 0.89 (95% CI 0.77–0.96). T1 mapping allows for non-invasive differentiation of malignant and non-malignant effusions in an ex-vivo set up.

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Dynamic characteristics of squeeze-type mount using magnetorheological fluid

Proceedings of the Institution of Mechanical Engineers Part K Journal of Multi-body Dynamics ◽

10.1243/146441905x10005 ◽

2005 ◽

Vol 219 (1) ◽

pp. 27-34 ◽

Cited By ~ 5

Author(s):

Y K Ahn ◽

J-Y Ha ◽

Y-H Kim ◽

B-S Yang ◽

M Ahmadian ◽

...

Keyword(s):

Dynamic Characteristics ◽

Experimental Analysis ◽

Vibration Isolation ◽

Dynamic Behaviour ◽

Electrical Current ◽

Magnetorheological Fluid ◽

Test Set ◽

Mr Fluid ◽

Set Up ◽

Stiffness And Damping

This paper presents an analytical and experimental analysis of the characteristics of a squeeze-type magnetorheological (MR) mount which can be used for various vibration isolation areas. The concept of the squeeze-type mount and details of the design of a squeeze-type MR mount are discussed. These are followed by a detailed description of the test set-up for evaluating the dynamic behaviour of the mount. A series of tests was conducted on the prototype mount built for this study, in order to characterize the changes occurring as a result of changing electrical current to the mount. The results of this study show that increasing electrical current to the mount, which increases the yield stress of the MR fluid, will result in an increase in both stiffness and damping of the mount. The results also show that the mount hysteresis increases with increase in current to the MR fluid, causing changes in stiffness and damping at different input frequencies.

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Fatigue Crack Growth Tests on Glass Fibre Reinforced Polymer Matrix Composite

Materials Science Forum ◽

10.4028/www.scientific.net/msf.473-474.189 ◽

2005 ◽

Vol 473-474 ◽

pp. 189-194

Author(s):

Zilia Csomós ◽

János Lukács

Keyword(s):

Cyclic Loading ◽

Crack Opening Displacement ◽

Matrix Composite ◽

Glass Fibre ◽

Crack Opening ◽

Loading Conditions ◽

Opening Displacement ◽

Interfacial Cracks ◽

Glass Fibre Reinforced ◽

Number Of Cycles

E-glass fibre reinforced polyester matrix composite was investigated, which was made by pullwinding process. Round three point bending (RTPB) specimens were tested under quasi-static and mode I cyclic loading conditions. Load vs. displacement (F-f), load vs. crack opening displacement (F-v) and crack opening displacement range vs. number of cycles (ΔCOD-N) curves were registered and analysed. Interfacial cracks were caused the final longitudinal fracture of the specimens under quasi-static and cyclic loading conditions.

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