91 research outputs found
Nonlinear Finite Element Analysis of Nanoindentation of Viral Capsids
Recent Atomic Force Microscope (AFM) nanoindentation experiments measuring
mechanical response of the protein shells of viruses have provided a
quantitative description of their strength and elasticity. To better understand
and interpret these measurements, and to elucidate the underlying mechanisms,
this paper adopts a course-grained modeling approach within the framework of
three-dimensional nonlinear continuum elasticity. Homogeneous, isotropic,
elastic, thick shell models are proposed for two capsids: the spherical Cowpea
Chlorotic Mottle Virus (CCMV), and the ellipsocylindrical bacteriophage . As analyzed by the finite element method, these models enable parametric
characterization of the effects of AFM tip geometry, capsid dimensions, and
capsid constitutive descriptions. The generally nonlinear force response of
capsids to indentation is shown to be insensitive to constitutive details, and
greatly influenced by geometry. Nonlinear stiffening and softening of the force
response is dependent on the AFM tip dimensions and shell thickness. Fits of
the models capture the roughly linear behavior observed in experimental
measurements and result in estimates of Young's moduli of 280--360 MPa
for CCMV and 4.5 GPa for .Comment: 24 pages, 10 figures, submitted to Biophysical Journa
The Effect of Phlebotomy on Renal Function and Proteinuria in a Patient with Congenital Cyanotic Heart Disease
Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures
Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo
Mechanisms leading to toxin-induced impairment of renal function, with a focus on immunopathology
Glomerular sclerosis in nephrotic rats:Comparison of the long-term effects of adriamycin and aminonucleoside
Glomerular sclerosis in nephrotic rats:Comparison of the long-term effects of adriamycin and aminonucleoside
Glomerular sclerosis in nephrotic rats: Comparison of the long-term effects of adriamycin and aminonucleoside
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