Free-radical retrograde precipitation-polymerization process

A free-radical retrograde polymerization process for forming a polymer. An admixture of reactants including predetermined amounts of a monomer, a solvent, and a free-radical-initiator is reacted. A precipitation polymerization reaction occurs such that a polymer-rich phase is at a temperature generally above the lower critical solution temperature (LCST) of the admixture.https://digitalcommons.mtu.edu/patents/1079/thumbnail.jp

Metabolomics for mitochondrial and cancer studies

AbstractMetabolomics, a high-throughput global metabolite analysis, is a burgeoning field, and in recent times has shown substantial evidence to support its emerging role in cancer diagnosis, cancer recurrence, and prognosis, as well as its impact in identifying novel cancer biomarkers and developing cancer therapeutics. Newly evolving advances in disease diagnostics and therapy will further facilitate future growth in the field of metabolomics, especially in cancer, where there is a dire need for sensitive and more affordable diagnostic tools and an urgency to develop effective therapies and identify reliable biomarkers to predict accurately the response to a therapy. Here, we review the application of metabolomics in cancer and mitochondrial studies and its role in enabling the understanding of altered metabolism and malignant transformation during cancer growth and metastasis. The recent developments in the area of metabolic flux analysis may help to close the gap between clinical metabolomics research and the development of cancer metabolome. In the era of personalized medicine with more and more patient specific targeted therapies being used, we need reliable, dynamic, faster, and yet sensitive biomarkers both to track the disease and to develop and evolve therapies during the course of treatment. Recent advances in metabolomics along with the novel strategies to analyze, understand, and construct the metabolic pathways opens this window of opportunity in a very cost-effective manner. This article is part of a Special Issue entitled: Bioenergetics of Cancer

Native American Cultural Identity through Imagery: An Activity Theory Approach to Image-Power

Draft of conference paperThe American Indian and Alaska Native (AIAN) community stands poised to take control of their cultural imagery and image-power through image-heavy social media platforms. Extant research demon- strates the high level of use of social media in AIAN communities, creating the opportunity to overcome negative representation by mass media in the past. However, despite evidence of social media use for cultural preservation, little is known about the exact ways in which image-power is managed. This exploratory study seeks to illuminate the ways in which advocates are presenting imagery, using a qualitative image analysis of advocates’ Instagram posts. Using an Activity Theory framework, particularly the construct of division of labor, we identify a novel taxonomy of imagery cate- gories and advocate roles. The roles, namely Informing, Rallying, Identifying, and Interacting, contribute to our understanding of the relationship between AIAN advocates and imagery, and the mediat- ing effects image-heavy social media platforms and advocate roles have on this relationship. Our findings also contribute to scholar- ship applying Activity Theory in the study of online communities. In particular, our findings delineate roles among material sharers within the construct of Division of Labor

Properties of Transfer-Molded Wood-Fiber/Polystyrene Composites

Transfer-molded composites combining polystyrene, wood particles, and three bi-functional coupling agents were prepared and evaluated for physical and mechanical properties. Pure 685D polystyrene (PS) (75-100% by weight) was combined with 100-mesh (0.15-mm sieve opening) particles prepared from thermomechanically pulped quaking aspen (Populus tremuloides) (0-25% by weight). Three coupling agents, polystyrene/poly(methacrylic) (both low and high molecular weight) and polystyrene/poly(vinyl acetate) developed at Michigan Technological University, were added in an effort to promote compatibility between the hygroscopic wood fiber and the non-polar hydrophobic polystyrene. Mechanical tensile testing was used to assess the respective composite's tensile elastic modulus and tensile strength. A polystyrene/poly(methacrylic) acid (PS-PMAA) coupling agent was found to be the most effective with regard to enhanced tensile elastic modulus at higher fiber-loading levels (enhancement levels of 11.3-23.8% over pure PS). A fiber/PS composite using low molecular weight PMAA (PS-PMAAL) as a coupling agent demonstrated the best tensile strength retention characteristics at higher fiber-loading levels. Initial results show high variability in material properties over the range of fiber-loading levels, and between coupling agent type. It is clear, however, that certain coupling agents do have a positive effect on composite properties

Mitochondria DNA mutations cause sex-dependent development of hypertension and alterations in cardiovascular function

Aging is associated with conduit artery stiffening that is a risk factor for and can precede hypertension and ventricular dysfunction. Increases in mitochondria DNA (mtDNA) frequency have been correlated with aging. Mice with a mutation in the encoding domain (D257A) of a proof-reading deficient version of mtDNA polymerase-γ (POLG) have musculoskeletal features of premature aging and a shortened lifespan. However, few studies using these mice have investigated the effects of mtDNA mutations on cardiovascular function. We hypothesized that the proof-reading deficient mtDNA POLG leads to arterial stiffening, hypertension, and ventricular hypertrophy. Ten to twelve month-old D257A mice (n=13) and age- and sex-matched wild-type controls (n=13) were catheterized for hemodynamic and ventricular function measurements. Left common carotid arteries (LCCA) were harvested for mechanical tests followed by histology. Male D257A mice had pulmonary and systemic hypertension, arterial stiffening, larger LCCA diameter (701±45 vs. 597±60 μm), shorter LCCA axial length (8.96±0.56 vs. 10.10±0.80 mm), and reduced hematocrit (29.1±6.1 vs. 41.3±8.1; all p<0.05). Male and female D257A mice had biventricular hypertrophy (p<0.05). Female D257A mice did not have significant increases in pressure or arterial stiffening, suggesting that the mechanisms of hypertension or arterial stiffening from mtDNA mutations differ based on sex. Our results lend insight into the mechanisms of age-related cardiovascular disease and may point to novel treatment strategies to address cardiovascular mortality in the elderly

Analysis of polymer membrane formation through spinodal decomposition

A phenomenological model used in a previous work for spinodal decomposition of polymer‐solvent systems is further analyzed. From the dimensionless form of the nonlinear Cahn‐Hilliard equation, the dimensionless induction time is found to be a constant number for suddenly quenched systems. Computer simulation is carried out for prediction of early stage behavior with thermal history corresponding to a linear temperature drop followed by a constant temperature vs. time. In the areas of polymer membrane formation and phase separation studies, the universality of the constant dimensionless Induction time for suddenly quenched systems allows the determination of the minimum time needed for phase separation via spinodal decomposition. Also, simulation results for the double linear temperature history allows the convenient prediction of early stage spinodal decomposition behavior at every point of a membrane cross section undergoing thermal inversion phase separation

Free-radical retrograde-precipitation copolymerization of vinyl acetate and acrylic acid

Free-radical chain, polymerization kinetics of vinyl acetate (VA) and acrylic acid (AA) exhibit some unusual control features. The VA radicals have a high rate of chain transfer leading to relatively sluggish propagation rates. Polymerization of AA, however, is prone to autoacceleration behavior in bulk, solution, and precipitating media. Thus, conventional statistical copolymerization of VA and AA would result in the preferential formation of high AA content copolymer. However, when the reaction medium is chosen in such a way that the copolymer precipitates above the lower critical solution temperature (LCST), propagation control and even monomer sequence control are obtained. Under these conditions, when the VA charge is much greater than AA, a tapered block copolymer (VA-t-AA) is obtained. We report a single stage polymerization, process for the synthesis of such materials. The presence of VA-t-AA products is verified by emulsification, solubility, fractionation, size exclusion chromatography, NMR, and thermal analyses. In addition, propagation control can virtually eliminate formation of bimodal MWD and random/ homopolymer materials that are associated with various chain transfer mechanisms in conventional polymerization routes