Hydrogels prepared from self-assembled cellulose nanofibrils (CNFs) are widely used in biomedicine, electronics and environmental technology. Their ability to serve as inks for extrusion-based 3D printing is conventionally evaluated by means of rheological tests. A model is developed that describes the response of CNF gels in small- and large-amplitude oscillatory tests in a unified manner. The model involves a reasonably small number of material parameters, ensures good agreement between results of simulation and observations in oscillatory tests and correctly predicts the stress-strain Lissajous curves, experimental data in hysteresis loop tests, and measurements of the steady-state viscosity. The model is applied to analyze how composition and preparation conditions for CNF gels affect transition from shear thinning to weak strain overshoot in large-amplitude shear oscillatory tests. Based on the model, simple relations are derived for the fractal dimension of CNF clusters and the storage modulus of gels prepared in aqueous solutions of multivalent salts. The validity of these equations is confirmed by comparison of their predictions with observations in independent tests.
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http://dx.doi.org/10.1016/j.jcis.2024.08.118 | DOI Listing |
J Neurosci
January 2025
Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Dr. Houghton, MI 49931.
Deep brain stimulation (DBS) effectively treats motor symptoms of advanced Parkinson's disease (PD), with the globus pallidus interna (GPi) commonly targeted. However, its therapeutic mechanisms remain unclear. We employed optogenetic stimulation in the entopeduncular nucleus (EP), the rat homologue of GPi, in a unilateral 6-OHDA lesioned female Sprague Dawley rat model of PD.
View Article and Find Full Text PDFMatrix Biol
January 2025
Department of Surgery, Emory University, Atlanta, GA, USA; Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; Research Services, Atlanta VA Medical Center, Decatur, GA, USA. Electronic address:
Arterial endothelial cells (ECs) reside in a complex biomechanical environment. ECs sense and respond to wall shear stress. Low and oscillatory wall shear stress is characteristic of disturbed flow and commonly found at arterial bifurcations and around atherosclerotic plaques.
View Article and Find Full Text PDFJ Sci Food Agric
January 2025
Department of Animal, Veterinary and Food Sciences, University of Idaho, Moscow, ID, USA.
Background: Determining the optimum water absorption capacity of gluten-free flours for an improved breadmaking process has been a challenge because there is no standard method. In the present study, large amplitude oscillatory shear (LAOS) tests were performed to explore the impact of different levels of added water on non-linear viscoelastic response of soy flour dough in comparison to wheat flour dough at a consistency of 500 BU.
Results: Among the LAOS parameters, large strain modulus (G') and large strain rate viscosity (η') were found to better probe the impact of added water amount on non-linear viscoelastic properties of soy flour dough.
Brain Struct Funct
January 2025
Behavioral Neuroscience Laboratory, Department of Psychology, Boğaziçi University, Bebek, 34342, Istanbul, Turkey.
Theta oscillations of the mammalian amygdala are associated with processing, encoding and retrieval of aversive memories. In the hippocampus, the power of the network theta oscillation is modulated by basal forebrain (BF) GABAergic projections. Here, we combine anatomical and computational approaches to investigate if similar BF projections to the amygdaloid complex provide an analogous modulation of local network activity.
View Article and Find Full Text PDFEntropy (Basel)
December 2024
Human Psychobiology Laboratory, Experimental Psychology Department, University of Seville, 41018 Seville, Spain.
Biological signals such as respiration (RSP) and heart rate (HR) are oscillatory and physiologically coupled, maintaining homeostasis through regulatory mechanisms. This report models the dynamic relationship between RSP and HR in 45 healthy volunteers at rest. Cross-correlation between RSP and HR was computed, along with regression analysis to predict HR from RSP and its first-order time derivative in continuous signals.
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