329 research outputs found
Aptamer-based colorimetric detection of various targets based on catalytic Au NPs/Graphene nanohybrids
No full textIn this paper, a label-free aptamer-based colorimetric assay was developed by incorporating catalytic Au nanoparticles/Graphene (Au NPs/Gr) nanohybrids. As an efficient peroxidase mimic, Au NPs/Gr can oxidize ABTS11 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) in the presence of H2O2, generating visible color change that can be recorded by a simple UV–vis spectrophotometer. The ssDNA aptamer can absorb on Au NPs/Gr interface through non-covalent interaction, thereby reducing the catalytic activity of Au NPs/Gr. In the presence of target molecule, the combination of aptamer with target caused the aptamer to assume a folded state and lose its ability to bind with Au NPs/Gr, leading to recovery of the catalytic activity of Au NPs/Gr. Base on this tunable strategy, calibration curves obtained for Hg2+ and MC-LR have detection limits of 3.63 nM and 7.14 ng/L with the linear range of 0.01–0.5 μM and 0.01–1.0 μg/L, respectively. These results indicated that various targets could be detected by this simple, rapid and universal colorimetric assay based on catalytic nanomaterials. Keywords: Aptamer, Colorimetric assay, Au nanoparticles, Graphene, Mercury ion, Microcystin-L
Two‐order superconvergence for a weak Galerkin method on rectangular and cuboid grids
No full textThis is the peer reviewed version of the following article: Wang, J., Wang, X., Ye, X., Zhang, S., Zhu, P., Two-order superconvergence for a weak Galerkin method on rectangular and cuboid grids, Numer. Methods Partial Differ. Eq.. (2022), 1– 15. https://doi.org/10.1002/num.22918, which has been published in final form at https://doi.org/10.1002/num.22918. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited. This article will be embargoed until 09/22/2023.This article introduces a particular weak Galerkin (WG) element on rectangular/cuboid partitions that uses k th order polynomial for weak finite element functions and ( k + 1 ) th order polynomials for weak derivatives. This WG element is highly accurate with convergence two orders higher than the optimal order in an energy norm and the L 2 norm. The superconvergence is verified analytically and numerically. Furthermore, the usual stabilizer in the standard weak Galerkin formulation is no longer needed for this element.The research of Junping Wang was supported by the NSF IR/D program, while working at National Science Foundation. However, any opinion, finding, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation. This research was supported in part by National Science Foundation Grant DMS-1620016, Zhejiang Provincial Natural Science Foundation of China (LY19A010008), and National Natural Science Foundation of China (12071184)
Three Pool Model of Calcium Signaling
No full textThesis is part of Honors ETD pilot project, 2008-2013. Migrated from Dspace in 2016.Mitochondria have been proposed to be an integral part of intracellular calcium signaling. We examine the two-pool model of intracellular calcium signaling by Goldbeter et al. 1990 [11] and propose a new model that uses the mitochondria. This creates a three-pool model for intracellular calcium signaling. We then proceed to discuss the differences between the two-pool and three-pool models by following the analysis of the two-pool model presented by Sneyd et al. 1993 [19]. The addition of the third pool does not change any of the dynamics of the two-pool model, but adds some functionality. The mitochondria acts like a buffer that has the ability to change the temporal dynamics, and we have a region of bistability that allows for dampened oscillations given the right stimulus and initial conditions.MathematicsBachelors of Science (BS
Circadian Oscillations of the Intestinal Stem Cell Lineage
No full textColorectal cancer is one of the most common forms of cancer, and it is widely accepted that it is initiated in the colon crypts. Consequently, a lot of work has been put into understanding the cell dynamics of intestinal crypts. In rodents, circadian oscillations have been observed in the three di erent cell populations at whole gut level. The goal of this thesis is to capture this phenomenon and draw biological conclusions. First, we look at previous models of a single intestinal crypt. The rst two lay the groundwork by introducing a compartmental approach, and the second two introduce methods for maintaining homeostasis. We capture the circadian phenomenon by introducing time delays to these older models. The time delays represent the time it takes the cell populations to send, receive, and respond to signals. In our models we observe that longer delays for the stem cell population lead to periodic solutions for all three cell populations. We conclude that the response of the stem cell population is delayed, and that this is related to the circadian oscillations
Circadian Oscillations of the Intestinal Stem Cell Lineage
No full textThesis is part of Honors ETD pilot project, 2008-2013. Migrated from Dspace in 2016.Colorectal cancer is one of the most common forms of cancer, and it is widely accepted that it is initiated in the colon crypts. Consequently, a lot of work has been put into understanding the cell dynamics of intestinal crypts. In rodents, circadian oscillations have been observed in the three different cell populations at whole gut level. The goal of this thesis is to capture this phenomenon and draw biological conclusions. First, we look at previous models of a single intestinal crypt. The first two lay the groundwork by introducing a compartmental approach, and the second two introduce methods for maintaining homeostasis. We capture the circadian phenomenon by introducing time delays to these older models. The time delays represent the time it takes the cell populations to send, receive, and respond to signals. In our models we observe that longer delays for the stem cell population lead to periodic solutions for all three cell populations. We conclude that the response of the stem cell population is delayed, and that this is related to the circadian oscillations.MathematicsBachelors of Science (BS
The Dynamical Behavior of a Two Patch Predator-Prey Model
No full textThesis is part of Honors ETD pilot project, 2008-2013. Migrated from Dspace in 2016.A two-patch Rosenzweig-MacArthur system describing predator-prey interaction in a spatially inhomogeneous environment is investigated. The global stability of equilibrium solutions for the homogeneous case is proved using Lyapunov functional, and stability analysis for the coexistence equilibrium is also given. Numerical bifurcation diagrams and numerical simulations of the limit cycle dynamics for the inhomogeneous case are obtained to compliment theoretical approach. Some of our results help to explain and clarify possible solutions to the Paradox of Enrichment in ecological studies.MathematicsBachelors of Science (BS
Optimal Collision Energy for Higgs Precision Measurements at the ILC250
No full textIn the context of the International Linear Collider, the following research aims to look for the best energies for this machine to work at in order to achieve the most precise measurements on Higgs related quantities. We will firstly focus on the measurement of the Higgsstrahlung cross-section, by carrying out a full model-independent analysis at three different energies, with the aim to minimize the relative error on this quantity. Afterwards, we will set up, in the framework of Effective Field Theories, a toy Lagrangian, and study the precision of anomalous couplings measurements at the energy points aforementioned. In order to do this, we will build up a chi-squared function at each energy point and look at their contours. The chi-squared functions we will construct exploit the new Lorentz structures present in our Lagrangian, making use of the different angular distribution predicted by this theory, and in particular of its energy dependence. We will also take linear combinations of the three chi-squared at the various energy points, aiming to improve our measurements by running the ILC at multiple energies in a short energy range
A New Method for Measuring Higgs Mass
No full textThe Higgs mass as one of the fundamental parameters in the Standard Model has been already measured with a precision of 110 MeV with the data collected so far at the LHC. However in some cases of looking for small deviations from the SM, current precision or projection of the Higgs mass measurement at the LHC or HL-LHC may not be enough. One prominent exam-ple is for the SM prediction of the Higgs partial decay width H → WW* or H → ZZ*, in which the Higgs mass uncertainty becomes one of the leading sources of parametric theory error. It is expected that at future e+e- colliders the Higgs mass precision can be significantly improved by the “recoil mass method”, at least statistically. This research proposes a new method which may complement to the recoil mass method in terms of systematic errors. The new method employs the signal channel of Higgs decaying to a pair of fermions, in particular τ leptons, or 2 quarks bb¯ and makes use of transverse momentum conservations alone instead of the 4-momentum conservation in the recoil mass method. The key experimental observables will be the momentum directions of tau leptons or b-jets without any input from energy measurement, and the momentum directions can possibly be measured by reconstructing the decaying vertex of the tau leptons or B-hadrons. This new method can in principle be applied at lepton colliders and the LHC as well. This method is studied by performing realistic detector simulation and physics analysis with the ILC frameworks based on the ILD. In the case of H → bb¯ without any background the statistical precision is found to be comparable to the expectation by recoil mass method, thus potentially very useful. The H → τ−τ+ channel is rather statistically limited and worth of further investigations
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