Drug Delivery System Based on Covalently Bonded Poly[N-Isopropylacrylamide-co-2-Hydroxyethylacrylate]-Based Nanoparticle Networks

Mathews, Anu,Ha, Chang-Sik,Cho, Won-Jei,Kim, Il Taylor Francis 2006 DRUG DELIVERY Vol.13 No.4

<P>The present work is focused on investigating the controlled drug release behavior of Poly [N-isopropylacrylamide-co-2-Hydroxyethylacrylate] (P [NIPAm-HEAc])-based hydrogel. The synthesis process includes the preparation of monodispersed hydrogel nanoparticles containing specific functional groups, followed by cross-linking to neighboring spheres to stabilize the entire network. The color and volume of these crystalline hydrogel networks can reversibly change in response to external stimuli such as temperature, pH, and other environmental conditions. The feasibility of the hydrogel as a controlled release vehicle for 5-fluorouracil is evaluated.</P>

Fully Aliphatic Polyimides – Influence of Adamantane and Siloxane Moieties

Mathews, Anu Stella,Kim, Il,Ha, Chang-Sik WILEY-VCH Verlag 2007 Macromolecular symposia Vol.249 No.1

<P>Series of fully aliphatic polyimides were prepared from cyclobutane- 1,2,3,4-tetracarboxylic dianhydride and aliphatic diamines. The variations of the basic properties of these polyimides as a result of the incorporation of adamantyl and siloxane moieties are examined. The structure of the polyimides where confirmed by FT-IR spectroscopy. It was found that polyimides with appropriate ratio of adamantane and siloxane groups showed excellent solubility, good thermal stability, high glass transition temperature, low dielectric constant and beneficial transparencies.</P>

Fully aliphatic polyimides from adamantane-based diamines for enhanced thermal stability, solubility, transparency, and low dielectric constant

Mathews, Anu Stella,Kim, Il,Ha, Chang-Sik Wiley Subscription Services, Inc., A Wiley Company 2006 Journal of applied polymer science Vol.102 No.4

<P>We have synthesized a series of fully aliphatic polyimides (APIs) from bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BOCA) and various aliphatic diamines, including linear aliphatic, flexible alicyclic, and rigid adamantyl diamines. We performed the polymerization reactions using one-step syntheses in m-cresol at elevated temperatures without the isolation of poly(amic) acid. The chemical composition and structure of the polymers were characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectrometry. The characterization data are reported from analyses using gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), and wide-angle X-ray diffraction (WXAD) measurements. The polyimides are also subjected to solubility, solution viscosity, tensile strength, transparency, and dielectric constant measurements. The resultant polyimides possess well-controlled molecular weight, reasonable intrinsic viscosity, good transparency, enhanced solubility, low dielectric constants, and high glass transition temperature, together with marginal thermal and mechanical stability. These properties were enhanced in copolyimides containing equimolar amounts of rigid and flexible moieties. These rigid-rod APIs derived from the alicyclic dianhydride and aliphatic diamines are promising candidates as advanced materials for future applications in micro- and photoelectronic devices. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3316–3326, 2006</P>

Comparative analysis of noise from three Falcon 9 launches

Mathews, Logan T.,Gee, Kent L.,Hart, Grant W.,Rasband, Reese D.,Novakovich, Daniel J.,Irarrazabal, Francisco I.,Vaughn, Aaron B.,Nelson, Pauline The Acoustical Society of Korea 2020 韓國音響學會誌 Vol.39 No.4

This study investigates the far-field noise from three Falcon 9 vehicle launches from Vandenberg Air Force Base, CA, USA, as measured from the same location within the nearby community of Lompoc. The overall sound pressure levels for the three launches are shown to be similar, but some differences in the early launch period are thought to be weather-related. The peak directivity angle in overall level is approximately 65 deg, which is consistent with horizontally-fired, static rocket data. For the third launch, waveforms and spectra are analyzed for different events during the launch sequence. The measured spectral bandwidth decreases with time, but spectral levels remain above the ambient noise throughout the main-engine firing. Additionally, late-launch phenomena observed in the data appear to be correlated with main-engine cutoff and second-stage engine start.

Synthesis, Characterization, and Properties of Fully Aliphatic Polyimides and Their Derivatives for Microelectronics and Optoelectronics Applications

Mathews Anu Stella,Kim Il,Ha Chang-Sik The Polymer Society of Korea 2007 Macromolecular Research Vol.15 No.2

Polyimides are one of the most important classes of polymers used in the microelectronics and photoelectronics industries. Because of their high thermal stability, chemical resistance, and good mechanical and electric properties, polyimides are often applied in photoresists, passivation and dielectric films, soft print circuit boards, and alignment films within displays. Recently, fully aliphatic and alicyclic polyimides have found applications as optoelectronics and inter layer dielectric materials, due to their good transparencies and low dielectric constants $(\varepsilon)$. The low molecular density, polarity and rare probability of forming inter- or intra-molecular charge transfers, resulting in lowering of the dielectric constant and high transparency, are the most striking characteristics of aliphatic polyimide. However, the ultimate end use of polyimides derived from aliphatic monomers is in their targeted applications that need less stringent thermal requirements. Much research effort has been exerted in the development of aliphatic polyimide with increased thermal and mechanical stabilities, while maintaining their transparencies and low dielectric constants, by the incorporation of rigid moieties. In this article, the recent research process in synthesizing fully aliphatic polyimides, with improved dimensional stability, high transparency and low $\delta$values, as well as the characterizations and future scope for their application in micro electric and photo-electronic industries, is reviewed.

Analysis of the role of M-type hexaferrite-based materials in electromagnetic interference shielding

Mathews Shalom Ann,Babu D. Rajan 한국물리학회 2021 Current Applied Physics Vol.29 No.-

M-type hexaferrite has attracted much attention for its large magneto-crystalline anisotropic energy, exceptionally good chemical stability, corrosion resistance, high Curie temperature, and high coercivity. In this review paper, our goal is to examine the microwave absorption properties and related studies of M-type hexaferritebased materials. The microwave absorption properties of hexaferrite-based materials in the S, X, and Ku-band are discussed with their corresponding reflection losses. Complementarity between magnetic loss and dielectric loss is found to have a great impact on the proper absorption of microwaves. The mechanisms corresponding to the microwave absorption in different morphologies and structural adaptations of hexaferrite have been elaborated in the article. The ongoing trends and future perspectives of these materials are also outlined.

Synthesis and characterization of soluble polyimides functionalized with carbazole moieties

Mathews, Anu Stella,Kim, Dongjo,Kim, Youngkyoo,Kim, Il,Ha, Chang-Sik Wiley Subscription Services, Inc., A Wiley Company 2008 Journal of polymer science Part A, Polymer chemist Vol.46 No.24

<P>Here, we report the synthesis and characterization of new soluble polyimides that are functionalized using carbazole moieties in their side chain. As a monomer for synthesizing the polyimides, 4″-carbazole-9-yl-[1,1′;2′,1″] terphenyl-4-4′-diamine and 2-(3-carbazol-9-yl-propyl)-biphenyl-4,4′-diamine were synthesized and then characterized using <SUP>1</SUP>H NMR, <SUP>13</SUP>C NMR, FTIR, UV–visible and photoluminescence spectroscopy, differential scanning calorimetry (DSC), and elemental analysis. The polyimides synthesized via chemical imidization processes were characterized with X-ray photoelectron spectroscopy, gel permeation chromatography, wide angle X-ray diffraction, thermogravimetric analysis, DSC, tensile strength measurement, and dielectric property measurement. Results showed that the synthesized polyimides were soluble in a variety of organic solvents, optically transparent in a visible range, thermally stable, mechanically strong, and considerably low dielectric. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8117–8130, 2008</P> <B>Graphic Abstract</B> <P>We report here new soluble semiconducting polyimides (PIs) containing carbazole moieties in the side chain. For dianydrides were used pyromellitic anhydride (PMDA) or 2, 2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA). The carbazole diamine derivatives are 4″-carbazole-9-yl-[1,1′;2′,1″] terphenyl-4-4′-diamine (CzTPDA) and 2-(3-carbazol-9-yl-propyl)-biphenyl-4,4′-diamine (CzHBPDA). All PIs showed high mechanical strength (>1.5 GPa) and extremely high glass transition temperature (>260 °C). Interestingly, most of PIs exhibited low dielectric constant below 3, whilstile the PI films were optically transparent in the visible range (>∼400 nm). Here are structures of CzTPDA and CzHBPDA synthesized in this work. <img src='wiley_img/0887624X-2008-46-24-POLA23109-gra001.gif' alt='wiley_img/0887624X-2008-46-24-POLA23109-gra001'> </P>

Use of Emoji as a Marketing Tool: An Exploratory Content Analysis

Mathews, Stanley,Lee, Seung-Eun The Costume Culture Association 2018 Fashion, industry and education Vol.16 No.1

The purpose of this exploratory study was to enhance the understanding of how brands tilize emojis in their marketing practices. A content analysis was conducted utilizing Google News as a search tool to access articles containing information pertaining to the use of emojis by brands. The combination of keywords used for the search were "emoji", "business", and "marketing". The search was narrowed down to the period of January $1^{st}$, 2014 - November $29^{th}$, 2017. This method generated a total of 604 trade publications with 55 of them providing information pertaining to specific brands and their use of emojis in their marketing strategies. A content analysis of trade publications has revealed that a variety of marketers have utilized emojis in their brand marketing practices. The entertainment, service, and food/drink industries have predominantly utilized emojis in their marketing practices, and their primary purpose for using emojis was to increase consumer engagement. Brands applied most of these emoji marketing strategies to an online or digital setting, whether it was social media pages, mobile applications, or any other form of computer-based marketing. Although there are limitations to this exploratory research in terms of its methodology, the findings of this study provide interesting insights into the potential of emojis as a marketing tool.

CONSTRAINTS ON PRE-INFLATION COSMOLOGY AND DARK FLOW

MATHEWS, GRANT J.,LAN, N.Q.,KAJINO, T. The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

If the present universe is slightly open then pre-inflation curvature would appear as a cosmic dark-flow component of the CMB dipole moment. We summarize current cosmological constraints on this cosmic dark flow and analyze the possible constraints on parameters characterizing the pre-inflating universe in an inflation model with a present-day very slightly open ${\Lambda}CDM$ cosmology. We employ an analytic model to show that for a broad class of inflation-generating effective potentials, the simple requirement that the observed dipole moment represents the pre-inflation curvature as it enters the horizon allows one to set upper and lower limits on the magnitude and wavelength scale of pre-inflation fluctuations in the inflaton field and the curvature parameter of the pre-inflation universe, as a function of the fraction of the total initial energy density in the inflaton field. We estimate that if the current CMB dipole is a universal dark flow (or if it is near the upper limit set by the Planck Collaboration) then the present constraints on ${\Lambda}CDM$ cosmological parameters imply rather small curvature ${\Omega}_k{\sim}0.1$ for the pre-inflating universe for a broad range of the fraction of the total energy in the inflaton field at the onset of inflation. Such small pre-inflation curvature might be indicative of open-inflation models in which there are two epochs of inflation.

Relativistic Hydrodynamics and Quasiperiodic Oscillations

MATHEWS GRANT J.,FRAGILE P. CHRIS,WILSON JANES R. The Korean Astronomical Society 2001 Journal of The Korean Astronomical Society Vol.34 No.4

We present preliminary numerical simulations of tilted-disk accretion around a rotating black hole. Our goal is to explore whether hydrodynamic instabilities near the Bardeen-Petterson radius could be responsible for generating moderate-frequency quasi-periodic oscillations in X-ray binaries. We review the relevant general relativistic hydrodynamic equations, and discuss preliminary results on the structure and dynamics of a thin, Keplerian disk.