610 research outputs found
Manipulated wettability of a superhydrophobic quartz crystal microbalance through electrowetting
No full textThe liquid phase response of quartz crystal microbalances (QCM) with a thin coating (~9 µm) of epoxy resin with and without a carbon nanoparticles top layer is reported. The nanoparticles convert the epoxy surface to a superhydrophobic one with a high static contact angle (~151º-155º) and low contact angle hysteresis (~1º-3.7º) where droplets of water are in the suspended Cassie-Baxter state. The frequency decrease of the fully immersed QCM with the superhydrophobic surface is less than with only epoxy layer, thus indicating a decoupling of the QCM response. A wettability transition to a liquid penetrating into the surface roughness state (for droplets a high contact angle hysteresis Wenzel state) was triggered using a molarity of ethanol droplet test (MED) and electrowetting; the MED approach caused some surface damage. The electrowetting induced transition caused a frequency decrease of 739 Hz at a critical voltage of ~100 V compared to the QCM in air. This critical voltage correlates to a contact angle decrease of 26º and a high contact angle hysteresis state in droplet experiments. These experiments provide a proof-of-concept that QCMs can be used to sense wetting state transitions and not only mass attachments or changes in viscosity-density products of liquids
Derek F. Connon, Innovation and renewal: A study of the theatrical works of Diderot, Voltaire Fondation, SVEC, 1989
No full textChouillet Jacques. Derek F. Connon, Innovation and renewal: A study of the theatrical works of Diderot, Voltaire Fondation, SVEC, 1989. In: Recherches sur Diderot et sur l'Encyclopédie, n°7, 1989. pp. 151-153
VAR, SVAR and SVEC Models: Implementation Within R Package vars
No full textThe structure of the package vars and its implementation of vector autoregressive, structural vector autoregressive and structural vector error correction models are explained in this paper. In addition to the three cornerstone functions VAR(), SVAR() and SVEC() for estimating such models, functions for diagnostic testing, estimation of a restricted models, prediction, causality analysis, impulse response analysis and forecast error variance decomposition are provided too. It is further possible to convert vector error correction models into their level VAR representation. The different methods and functions are elucidated by employing a macroeconomic data set for Canada. However, the focus in this writing is on the implementation part rather than the usage of the tools at hand.
Monolithic columns with a gradient of functionalities prepared via photoinitiated grafting for separations using capillary electrochromatography
No full textStationary phases for capillary electrochromatography with a longitudinal gradient of functionalities have been prepared via photoinitiated grafting of polymer chains onto the pore surface of a porous polymer monolith. In order to achieve the desired retention
and electroosmotic flow, the hydrophobic poly(butyl methacrylate-co-ethylene dimethacrylate) monolith with optimized porous properties was grafted with a layer of ionizable polymer, poly(2-acrylamido-2-methyl-1-propanesulfonic acid). A moving shutter and a neutral density filter were used to control the dose of UV light received at different locations along the monolith in order to create the longitudinal gradient of functionalities. Formation of the desired gradients was confirmed using electron probe microanalysis of different locations along the column. The preparation technique
significantly affects performance in the CEC mode as demonstrated on the separations of a model mixture using columns both with homogeneous distribution of grafts and with a gradient of functionality. Columns grafted with the gradient of functionalities
were found superior to those functionalized uniformly. A comparison of the performance of the gradient column with another containing evenly distributed functionalities showed the performance benefits of the “gradient” column
Morphologic and antigenic properties of mouse mammary tumor virus produced in a hormone-responsive fashion by C57Bl/10 mammary tumors of non-viral origin.
No full text
Development of imidazotetrazines for the treatment of glioblastoma & as synthetic precursors to diazo species
No full textGlioblastoma multiforme (GBM), a grade IV astrocytoma, is the most prevalent, aggressive, and deadly form of malignant brain tumor with only 10% of patients surviving five years. The current standard treatment for GBM patients is bulk surgical resection and radiotherapy with concomitant and adjuvant temozolomide (TMZ), a small molecule DNA alkylating agent. The antitumor effect of TMZ is ultimately mediated through methylation of the O6-position of guanine and subsequent mismatch repair (MMR)-dependent cell death. Although TMZ was first synthesized in 1984 and has been FDA approved for two decades, certain key derivatives have been inaccessible due to synthetic challenges, precluding a broad exploration of the link between imidazotetrazine structure and biological activity. Novel synthetic strategies provided access to several new classes of C8-substituted imidazotetrazines and an evaluation of their aqueous stabilities enabled the derivation of a predictive model for imidazotetrazine hydrolytic stability based on the Hammett constant of the C8 substituent. Promising compounds modified at the C8 position were identified and found to have appropriate hydrolytic stability, enhanced blood-brain barrier permeability, lower hematological toxicity profiles, and superior activity relative to TMZ in a mouse model of GBM.
Despite its widespread use, certain GBM patient populations do not respond to TMZ therapy. Expression of O6-methylguanine DNA methyltransferase (MGMT) and loss of MMR function are the primary clinical modes of resistance to TMZ. Imidazotetrazine analogs modified at the N3 position were designed to deliver alternative DNA adducts that were irremovable by MGMT. An analog bearing a propargyl group at N3 demonstrated MGMT-independent activity in GBM cells in culture. Tuning the stability with an electron-donating chloro substituent at the C8 position produced novel dual-substituted imidazotetrazine CPZ, which displayed anticancer activity irrespective of MGMT expression and MMR status.
Imidazotetrazines such as TMZ are precursors to alkyl diazoniums, used therapeutically to alkylate DNA and elicit an anticancer effect. Given their stability as prodrugs and the reactivity of the species released, imidazotetrazines were repurposed into synthetic surrogates for diazomethane and other diazoalkanes. TMZ was employed to conduct esterifications and metal-catalyzed cyclopropanations, with methyl ester formation from a wide variety of substrates proving efficient and operationally simple. As a commercially available solid that is non-explosive and non-toxic, TMZ should find broad utility as a synthetic replacement for diazomethane.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2022-05-01The student, Riley Svec, accepted the attached license on 2020-04-14 at 17:59.The student, Riley Svec, submitted this Dissertation for approval on 2020-04-14 at 18:07.This Dissertation was approved for publication on 2020-04-16 at 13:46.DSpace SAF Submission Ingestion Package generated from Vireo submission #14980 on 2020-08-25 at 17:40:15Made available in DSpace on 2020-08-27T00:49:56Z (GMT). No. of bitstreams: 3
SVEC-DISSERTATION-2020.pdf: 8059578 bytes, checksum: ab3d1ff4d70e46feebfe7065362e6fd6 (MD5)
LICENSE.txt: 4207 bytes, checksum: bfa97cf20b5f230ffb30c8c48117f776 (MD5)
PROQUEST_LICENSE.txt: 4553 bytes, checksum: 4a11a8619e7c0ee6114da31205b9eda3 (MD5)
Previous issue date: 2020-04-16Embargo set by: Seth Robbins for item 115864
Lift date: 2022-08-27T00:50:22Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 115864
Lift date: 2022-08-27T00:51:40Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemAuthor requested closed access (OA after 2yrs) in Vireo ETD systemLimite
Solving Existentially Quantified Constraints with One Equality and Arbitrarily Many Inequalities
No full textThis paper contains the first algorithm that can solve disjunctions of constraints of the form \exists\SVec{y}\STI B \; [ f=0 \;\wedge\; g_1\geq 0\wedge\dots\wedge g_k\geq 0 ] in free variables \SVec{x}, terminating for all cases when this results in a numerically well-posed problem. Here the only assumption on the terms is the existence of a pruning function, as given by the usual constraint propagation algorithms or by interval evaluation. The paper discusses the application of an implementation of the resulting algorithm on problems from control engineering, parameter estimation, and computational geometry
Micro-HPLC of proteins using a novel monolithic stationary phase with a gradient of functionalities prepared via photoinitiated grafting
No full textThe use of photografting for the functionalization of porous poly(butyl methacrylate-co-ethylene dimethacrylate) monolithic columns enabled the preparation of columns with a homogeneously grafted poly(2-acrylamido-2-methyl-1-propanesulfonic acid, AMPS) chains. Recently, novel monolithic columns with a longitudinal gradient of concentration of functional groups were prepared and characterized using electron probe microanalysis and the separation performance evaluated in CEC. We demonstrated that these monolithic columns afforded higher separation efficiency and peak capacity compared to their homogeneously grafted counterparts. Consequently, the application of monolithic columns with this new type of chemistry enabled rapid and efficient separations. In this study, we now demonstrate the applicability of the new type of monolithic columns in μ-HPLC. For example, the separation of proteins in ion-exchange mode was studied. Optimization of the chromatographic conditions such as the shape of the mobile phase gradient and the flow rate allowed a rapid separation of four proteins in a short period of time. We also found that the stationary phase involving the gradient of functionalities exhibited high selectivity. These separation methods can be useful in the proteomic research
- …
