31 research outputs found
UV Exposed Optical Fibers with Frequency Domain Reflectometry for Device Tracking in Intra-Arterial Procedures
Shape tracking of medical devices using strain sensing properties in optical
fibers has seen increased attention in recent years. In this paper, we propose
a novel guidance system for intra-arterial procedures using a distributed
strain sensing device based on optical frequency domain reflectometry (OFDR) to
track the shape of a catheter. Tracking enhancement is provided by exposing a
fiber triplet to a focused ultraviolet beam, producing high scattering
properties. Contrary to typical quasi-distributed strain sensors, we propose a
truly distributed strain sensing approach, which allows to reconstruct a fiber
triplet in real-time. A 3D roadmap of the hepatic anatomy integrated with a 4D
MR imaging sequence allows to navigate the catheter within the
pre-interventional anatomy, and map the blood flow velocities in the arterial
tree. We employed Riemannian anisotropic heat kernels to map the sensed data to
the pre-interventional model. Experiments in synthetic phantoms and an in vivo
model are presented. Results show that the tracking accuracy is suitable for
interventional tracking applications, with a mean 3D shape reconstruction
errors of 1.6 +/- 0.3 mm. This study demonstrates the promising potential of
MR-compatible UV-exposed OFDR optical fibers for non-ionizing device guidance
in intra-arterial procedures
A comparison of the absolute reactivity of monomers, 1. Kinetic study of radical polymerization of acrylamide and methacrylamide, initiated by manganese(III) acetate
The kinetics of polymerization of acrylamide (AAM) and methacrylamide (MAM) with manganese(III) acetate as thermal initiator was studied. In the temperature range between 303 and 313 K, the initial rate of polymerization follows the relation: v=k[Monomers] · [Initiator]<SUP>½</SUP>. The rate of initiation of the polymerization was determined from the rate of decomposition of manganese(III) acetate. The reactivity of the two monomers under the same conditions was compared
Kinecits and mechanism of oxidation of Isobutyric acid and acidic acid by Mn (III)
This article does not have an abstract
A comparison of the absolute reactivity of vinyl monomers. II
The kinetics of polymerization of acrylamide (AM), acrylic acid (AA) and acrylonitrile (AN) initiated by the redox system, Mu3+ - isobutyric acid (IBA), was studied in the temperature range 30 - 50°C. Acrylamide and acrylic acid polymerization kinetics followed the same mechanism, viz., initiation by primary radical and termination by both Mn8+ ion and Mn3+ - isobutyric acid (intermediate) complex. But in acrylonitrile polymerization, termination by Mn3+ ion alone was observed. Also the complex termination step was found to be absent in acrylic acid polymcrization when the [Mn3t] was kept very low. The rate coefficients kp / ku and kJ / ko were related to the polymer radical reactivity and monomer reactivity respectively. It was found that while kp / ko follows the order AN > AA, the kl / ko follows the reverse order
Kinetics of Oxidation of Cinnamic & Crotonic Acids by Manganese(III) Acetate in 90 % Acetic Acid
488-49
Kinetics of polymerization of vinyl monomers initiated by manganese(III) acetate. I
The kinetics of thermal polymerization of acrylic acid (AA), methacrylic acid (MAA), acrylonitrile (AN), and methacryl-amide (MAM) in aqueous sulfuric acid using manganic acetate was studied. The effect of variations in [monomer], [Mn<SUP>3+</SUP>], [H<SUP>+</SUP>], μ, and temperature on the rates of monomer disappearance (R<SUB>p</SUB>), Mn<SUP>3+</SUP> disappearance (−R<SUB>m</SUB>), and the degree of polymerization (X<SUB>n</SUB>) were studied. Based on the kinetic results, a suitable reaction scheme is proposed and rate expressions are derived. The rate constants, such as k<SUB>i</SUB>, k<SUB>p</SUB>/k<SUB>t</SUB>, and thermo-dynamic parameters, corresponding to these are evaluated
Structure and reactivity of vinyl monomers in radical polymerization. 1. Kinetics of polymerization initiated by Manganese (III) acetate
This article does not have an abstract