Search results for "Fibril"

Influence of saline and pH on collagen type I fibrillogenesis in vitro: Fibril polymorphism and colloidal gold labelling

2007

We have produced different collagen type I fibrils by in vitro fibrillogenesis of acetic acid-soluble collagen within the pH range 2.5-9.0, in the presence and absence of 150 mM NaCl. The varying relatively stable molecular assemblies and polymorphic fibrillar end-products produced after 24 h incubation have been assessed and compared by the TEM study of specimens negatively stained with uranyl acetate. In the presence of 150 mM NaCl, the assembly of collagen at low pH (2.5) leads to the formation of initial molecular aggregates that progressively link together at slightly higher pH (5.0) to form sub-fibrils and spindle-shaped D-banded bundles of sub-fibrils. At pH 6.0 these D-banded bundle…

Scalable manufacturing of fibrous nanocomposites for multifunctional liquid sensing

2021

This research is supported by the Advanced Manufacturing Program (No. 1927623) from the National Science Foundation and by the McIntire-Stennis Cooperative Forestry Research Program (No. 1020630) from the USDA National Institute of Food and Agriculture. The authors also thank WestRock Paper Company for donated the wood pulp used in this research. Open access funding is enabled and organized by CERN. Cellulose-based paper electronics is an attractive technology to meet the growing demands for naturally abundant, biocompatible, biodegradable, flexible, inexpensive, lightweight and highly miniaturizable sensory materials. The price reduction of industrial carbon nanotube (CNT) grades offers op…

A mechanistic model on the role of “radially-running” collagen fibers on dissection properties of human ascending thoracic aorta.

2014

Aortic dissection (AoD) is a common condition that often leads to life-threatening cardiovascular emergency. From a biomechanics viewpoint, AoD involves failure of load-bearing microstructural components of the aortic wall, mainly elastin and collagen fibers. Delamination strength of the aortic wall depends on the load-bearing capacity and local micro-architecture of these fibers, which may vary with age, disease and aortic location. Therefore, quantifying the role of fiber micro-architecture on the delamination strength of the aortic wall may lead to improved understanding of AoD. We present an experimentally-driven modeling paradigm towards this goal. Specifically, we utilize collagen fib…

Online measurement of floc size, viscosity, and consistency of cellulose microfibril suspensions with optical coherence tomography

2021

AbstractIn this study, cellulose microfibril (CMF) suspensions were imaged during pipe flow at consistencies of 0.4%, 1.0%, and 1.6% with optical coherence tomography (OCT) to obtain images of the structure and the local velocity of the suspension. The viscosities obtained by combining pressure loss measurement with the OCT velocity data showed typical shear thinning behavior and were in excellent agreement with viscosities obtained with ultrasound velocity profiling. The structural OCT images were used to calculate the radial and the axial floc sizes of the suspension. A fit of power law to the geometrical floc size–shear stress data gave the same power law index for all consistencies, sug…

Characterization of micro-fibrillated cellulose fiber suspension flow using multi scale velocity profile measurements

2017

Rheological properties and boundary layer flow behavior of Micro Fibrillated Cellulose (MFC) suspended in water was studied using a novel velocity profiling rheometric technique. The method is based on measuring stationary velocity profiles of fluid flow in a straight tube simultaneously by Doppler Optical Coherence Tomography (DOCT) and by Ultrasound Velocity Profiling (UVP). The high resolution DOCT provides velocity profiles near the transparent tube wall, while UVP yields corresponding information in the interior parts of the flow. The data from the two instruments is combined into a comprehensive velocity profile including both the thin boundary layer near the wall and the interior par…

Nanoporous kaolin

2017

Cellulose nano- and microfibrils (CNF/CMF) grades vary significantly based on the raw materials and process treatments used. In this study four different CNF/CMF grades were combined with kaolin clay pigment particles to form nanoporous composites. The attained composite properties like porosity, surface smoothness, mechanical properties and density properties depended strongly on the raw materials used. In general, higher kaolin content (~80 wt%) led to controllable shrinkage during drying, which resulted in improved dimensional stability of composites, compared to a lower kaolin content (~50 wt%). On the other hand, the use of a plasticizer and a high amount of CNF/CMF was essential to pr…

On the mechanism of fibril growth in polycarbonate and poly(methyl methacrylate) crazes

1982

Non-valvular Atrial Fibrillation in CKD: Role of Vitamin K Antagonists and Direct Oral Anticoagulants. A Narrative Review

2021

Atrial fibrillation (AF) is the most common arrhythmia in chronic kidney disease (CKD), with a close bidirectional relationship between the two entities. The presence of CKD in AF increases the risk of thromboembolic events, mortality and bleeding. Vitamin K antagonists (VKA) have been the mainstay of treatment for the prevention of thromboembolic events in AF until recently, with confirmed benefits in AF patients with stage 3 CKD. However, the risk-benefit profile of VKA in patients with AF and stages 4–5 CKD is controversial due to the lack of evidence from randomized controlled trials. Treatment with VKA in CKD patients has been associated with conditions such as poorer anticoagulation q…

Management of Direct Oral Anticoagulants in Patients with Atrial Fibrillation Undergoing Cardioversion

2019

Atrial fibrillation the most common cardiac arrhythmia. Its incidence rises steadily with each decade, becoming a real “epidemic phenomenon”. Cardioversion is defined as a rhythm control strategy which, if successful, restores normal sinus rhythm. This, whether obtained with synchronized shock or with drugs, involves a periprocedural risk of stroke and systemic embolism which is reduced by adequate anticoagulant therapy in the weeks before or by the exclusion of left atrial thrombi. Direct oral anticoagulants are safe, manageable, and provide rapid onset of oral anticoagulation; they are an important alternative to heparin/warfarin from all points of view, with a considerable reduction in b…

CATHAR : CATHeter for ARRhythmias : determination of depth of burned biological tissues with microwave

2015

Cardiac arrhythmia substrates may be treated by intracardiac ablations which consist in burning specific atrial or ventricular endocardial substrates. Created lesions which are not transmural may be responsible for arrhythmia recurrences. To date, the depth of the lesion inside the endocardium can't be assessed accurately during the procedures. Our experimental work has focused on microwave characterization of biological tissues (in vitro) to assess the burn depth. Using a reflection technique with a coaxial probe in contact with tissues, measurements were made over a wide frequency range (100 MHz to 6 GHz). The measured reflection coefficient is known to be directly related to the dielectr…