Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
1,880
result(s) for
"Kirk, Russell"
Sort by:
3D-Printed Biocompatible Frames for Electrospun Nanofiber Membranes: An Enabling Biofabrication Technology for Three-Dimensional Tissue Models and Engineered Cell Culture Platforms
Electrospun nanofiber membranes (ESNFMs) are exceptional biomaterials for tissue engineering, closely mimicking the native extracellular matrix. However, their inherent fragility poses significant handling, processing, and integration challenges, limiting their widespread application in advanced 3D tissue models and biofabricated devices. This study introduces a novel and on-mat framing technique utilizing extrusion-based printing of a UV-curable biocompatible resin (Biotough D90 MF) to create rigid, integrated support structures directly on chitosan–polyethylene oxide (PEO) ESNFMs. We demonstrate fabrication of these circular frames via precise 3D printing and a simpler manual stamping method, achieving robust mechanical stabilization that enables routine laboratory manipulation without membrane damage. The resulting framed ESNFMs maintain structural integrity during subsequent processing and exhibit excellent biocompatibility in standardized extract assays (116.5 ± 12.2% normalized cellular response with optimized processing) and acceptable performance in direct contact evaluations (up to 78.2 ± 32.4% viability in the optimal configuration). Temporal assessment revealed characteristic cellular adaptation dynamics on nanofiber substrates, emphasizing the importance of extended evaluation periods for accurate biocompatibility determination of three-dimensional scaffolds. This innovative biofabrication approach overcomes critical limitations of previous handling methods, transforming delicate ESNFMs into robust, easy-to-use components for reliable integration into complex cell culture applications, barrier tissue models, and engineered systems.
Journal Article
Development of a tomato xylem-mimicking microfluidic system to study Ralstonia pseudosolanacearum biofilm formation
The bacterial wilt pathogen Ralstonia pseudosolanacearum (Rps) colonizes plant xylem vessels and blocks the flow of xylem sap by its biofilm (comprising of bacterial cells and extracellular material), resulting in devastating wilt disease across many economically important host plants including tomatoes. The technical challenges of imaging the xylem environment, along with the use of artificial cell culture plates and media in existing in vitro systems, limit the understanding of Rps biofilm formation and its infection dynamics. In this study, we designed and built a microfluidic system that mimicked the physical and chemical conditions of the tomato xylem vessels, and allowed us to dissect Rps responses to different xylem-like conditions. The system, incorporating functional surface coatings of carboxymethyl cellulose-dopamine, provided a bioactive environment that significantly enhanced Rps attachment and biofilm formation in the presence of tomato xylem sap. Using computational approaches, we confirmed that Rps experienced linear increasing drag forces in xylem-mimicking channels at higher flow rates. Consistently, attachment and biofilm assays conducted in our microfluidic system revealed that both seeding time and flow rates were critical for bacterial adhesion to surface and biofilm formation inside the channels. These findings provided insights into the Rps attachment and biofilm formation processes, contributing to a better understanding of plant-pathogen interactions during wilt disease development.
Journal Article
Developments in Modern Racecar Driver Crash Protection and Safety
For many years, the evolution of safety improvements in motorsports was the result of a combination of science and perceived safe practices. Most safety developments were not based on rigorous laboratory testing, but rather on intuition and a “let’s try it and see what happens” approach. During the last few decades, motorsports has benefited from the organized research efforts made possible by academia, manufacturers, and sanctioning bodies, leading to present-day motorsports safety methodologies based on solid data and testing. This compendium, edited by some of the foremost racing safety experts, comprises selected technical papers that document the development and implementation of key motorsports safety technologies now in use. It is intended to provide racing professionals and enthusiasts with a concise overview of the significant engineering developments in motorsports driver safety that has occurred during the past two decades. The 13 papers chosen for this compendium, published between 1990 and 2013, reflect landmark safety studies and developments of that time. Eleven of the papers were published by SAE International and two were presented at the Stapp Car Crash Conference. The papers cover the following topics: • Crash testing simulations • Human crash injury and survival • Reducing driver injury in severe crashes • Head and neck restraints, including the HANS device • Race car seats • Restraint systems • Track safety and barrier systems The final paper is a study on the detailed performance of restraint systems and seats in examples of severe stock car crashes. The paper represents a succinct example of modern crash investigation of racing crashes with crash recording data, detailed injury analysis, and protective system performance. The progress in motorsports safety, as described in this compendium, has been dramatically effective in reducing driver injuries at the top levels of motorsports. Unfortunately, this is not true at the lower levels, where drivers continue to suffer preventable injuries and fatalities.
eBook
Dark Matter Genesis
There is abundant evidence pointing to an unseen component of the Universe comprising approximately 80% of its mass; this dark matter cannot be any known particle, and so demands new physics. Very little is known about dark matter, however from the cosmic microwave background, its abundance has been accurately measured. How this is produced then dictates the requirements placed on a theory of dark matter. Here four works [1-4] are described where theories of dark matter genesis are explored. The first mechanism considers an additional source of dark matter from decaying topological defects in the early Universe. Topological defects are massive structures formed during spontaneous symmetry breaking phase transitions, which evolve under their own tension and decay, possibly producing dark matter during freeze-out. This allows the annihilation cross-section to rise above what is required in standard freeze-out, as the losses in abundance it predicts, may be recuperated by the contributions from the decaying defects. Given this, the constraints standard freeze-out imposes on dark matter models can be loosen. This is illustrated by implementing the mechanism in an example theory, the Inert Doublet Model, where it opens up large swathes of parameter space and allows for lighter dark matter masses. Furthermore this mechanism is employed to resolve issues with dark matter interpretations of the galactic centre gamma-ray excess seen by Fermi-LAT. The cross-section required to produce this signal is in tension with limits from searches in dwarf spheroidal satellite galaxies. Using this mechanism in a p-wave annihilating model of dark matter, this tension is avoided while producing the correct relic abundance of dark matter. Additionally we examine the direct detection signatures in upcoming detectors, DEAP-3600 and XENON1T, of nuclear dark matter: bound states of strongly-interacting dark nucleons, formed during a synthesis period in the early Universe. Scatterings of states in this model produce characteristic recoil spectra, which we found can be distinguished to 3 sigma confidence level from WIMP spectra with as few as ~24 events. Subsequently there is potential for discovery in the not too distant future.
Dissertation
Largest Number of Subtrees of Trees with a Given Maximum Degree
We characterize trees, given a size and maximum vertex degree, which have the greatest number of subtrees. This generalizes the recent result of Szekely and Wang. These trees coincide with those which were shown by Fischermann et al., and independently Jelen and Triesch, to minimize the Wiener index.
Journal Article
Dark Matter from Decaying Topological Defects
We study dark matter production by decaying topological defects, in particular cosmic strings. In topological defect or \"top-down\" (TD) scenarios, the dark matter injection rate varies as a power law with time with exponent \\(p-4\\). We find a formula in closed form for the yield for all \\(p < 3/2\\), which accurately reproduces the solution of the Boltzmann equation. We investigate two scenarios (\\(p=1\\), \\(p=7/6\\)) motivated by cosmic strings which decay into TeV-scale states with a high branching fraction into dark matter particles. For dark matter models annihilating either by s-wave or p-wave, we find the regions of parameter space where the TD model can account for the dark matter relic density as measured by Planck. We find that topological defects can be the principal source of dark matter, even when the standard freeze-out calculation under-predicts the relic density and hence can lead to potentially large \"boost factor\" enhancements in the dark matter annihilation rate. We examine dark matter model-independent limits on this scenario arising from unitarity and discuss example model-dependent limits coming from indirect dark matter search experiments. In the four cases studied, the upper bound on \\(G\\mu\\) for strings with an appreciable channel into TeV-scale states is significantly more stringent than the current Cosmic Microwave Background limits.
Paper
Dark Matter with Topological Defects in the Inert Doublet Model
We examine the production of dark matter by decaying topological defects in the high mass region \\(m_{\\mathrm{DM}} \\gg m_W\\) of the Inert Doublet Model, extended with an extra U(1) gauge symmetry. The density of dark matter states (the neutral Higgs states of the inert doublet) is determined by the interplay of the freeze-out mechanism and the additional production of dark matter states from the decays of topological defects, in this case cosmic strings. These decays increase the predicted relic abundance compared to the standard freeze-out only case, and as a consequence the viable parameter space of the Inert Doublet Model can be widened substantially. In particular, for a given dark matter annihilation rate lower dark matter masses become viable. We investigate the allowed mass range taking into account constraints on the energy injection rate from the diffuse \\(\\gamma\\)-ray background and Big Bang Nucleosynthesis, together with constraints on the dark matter properties coming from direct and indirect detection limits. For the Inert Doublet Model high-mass region, an inert Higgs mass as low as \\(\\sim 200\\) GeV is permitted. There is also an upper limit on string mass per unit length, and hence the symmetry breaking scale, from the relic abundance in this scenario. Depending on assumptions made about the string decays, the limits are in the range \\(10^{12}\\) GeV to \\(10^{13}\\) GeV.
Paper
“Social Justice and Mass Culture” (1954)
A friend of mine has the misfortune of owning a number of stone cottages. I say “misfortune” because the cottages are in Scotland, and their rents are fixed at the level of 1914. The cottages were built long before 1914—some of them are eighteenth-century work, with their pan-tiled roofs and trick rubble walls and irregular little windows; but they are good to look upon still, with their white door-sills and their little gardens along the path to the road. The law compels my friend to keep them in tolerable repair, if they are tenanted, and to pay most of
Book Chapter