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Sample records for acer pseudoplatanus polymerizes

  1. Rapid degradation of abnormal proteins in vacuoles from Acer pseudoplatanus L. cells

    International Nuclear Information System (INIS)

    Canut, H.; Alibert, G.; Carrasco, A.; Boudet, A.M.

    1986-01-01

    In Acer pseudoplatanus cells, the proteins synthesized in the presence of an amino acid analog ([ 14 C]p-fluorophenylalanine), were degraded more rapidly than normal ones ([ 14 C]phenylalanine as precursor). The degradation of an important part of these abnormal proteins occurred inside the vacuoles. The degradation process was not apparently associated to a specific proteolytic system but was related to a preferential transfer of these aberrant proteins from the cytoplasm to the vacuole

  2. Hypoglycin A concentrations in seeds of Acer pseudoplatanus trees growing on atypical myopathy-affected and control pastures.

    Science.gov (United States)

    Unger, L; Nicholson, A; Jewitt, E M; Gerber, V; Hegeman, A; Sweetman, L; Valberg, S

    2014-01-01

    Hypoglycin A, found in seeds of Acer negundo, appears to cause seasonal pasture myopathy (SPM) in North America and is implicated in atypical myopathy (AM) in Europe. Acer negundo is uncommon in Europe. Thus, the potential source of hypoglycin A in Europe is unknown. We hypothesized that seeds of Acer pseudoplatanus were the source of hypoglycin A in Europe. Our objective was to determine the concentration of hypoglycin A in seeds of A. pseudoplatanus trees located in pastures where previous cases of AM had occurred. None. University of Berne records were searched to retrospectively identify 6 farms with 10 AM cases and 11 suspected AM deaths between 2007 and 2011. During October 2012, A. pseudoplatanus seeds were collected from 2 to 6 trees per pasture on 6 AM farms (7 pastures) from trees in or close to 2 pastures on 2 control farms where AM had not been previously reported. Hypoglycin A in seeds was analyzed by GC-MS. Acer pseudoplatanus trees were identified on all AM pastures. Hypoglycin A was detected in all A. pseudoplatanus seeds in highly variable concentrations ranging from 0.04 to 2.81 μg/mg (mean 0.69) on AM farms and 0.10 to 9.12 μg/mg (mean 1.59) on control farms. Preventing horses from grazing pastures containing A. pseudoplatanus seeds during late fall and early spring might be the best means to prevent AM. Copyright © 2014 by the American College of Veterinary Internal Medicine.

  3. Morphometric characteristics of sycamore maple (Acer pseudoplatanus L. fruits in Novi Sad urban populations

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    Kostić Saša

    2017-01-01

    Full Text Available This paper shows the results of the analysis of the fruit morphometric characteristics of 29 trees of sycamore maple (Acer pseudoplatanus L. and red - leaf sycamore maple (Acer pseudoplatanus ‘Аtropurpureum’ Späth. in Novi Sad area. Based on the test trees, it can be concluded that the analyzed secondary population of sycamore maple has a high level of intra - populations variability, based on different degrees of variability of measured parameters and statistically significant differences of all analyzed parameters within the analysed genotypes. The results indicate that there are certain differences between fruit of sycamore maple and its red - leaf variety. Given that there is no statistically significant difference between sites and different urban spaces, it can be concluded that stress factors caused by a high degree of urbanity do not affect the morphometric characteristics of fruits in the analyzed test trees. Testing the symmetry of fruits indicates a high level of genetic variability within the analyzed population.

  4. RHEOLOGICAL BEHAVIOUR OF CURLYMAPLE WOOD (ACER PSEUDOPLATANUS USED FOR BACK SIDE OF VIOLIN

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    Mariana Domnica STANCIU

    2015-12-01

    Full Text Available Stringed instruments are made of high quality wood species from physical, mechanical and acoustical point of view, being carefully selected, kiln dried and processed under specific conditions that assure micro-structural integrity. Maple wood (Acer Pseudoplatanus for musical instruments is used to getting back plates and sides for string instruments (violin family. This species of wood is valued for both acoustic qualities but mostly for aesthetic, using a natural defect of maple wood characterized by wavy grain. The paper presents the research on visco-elasticity behavior of maple wood with different types of grain deviation in wood from very curly maple to common maple. The storage modulus, loss modulus, damping capacity in varying temperature conditions and for different loading frequencies were determined using dynamical mechanical analysis (DMA. It was found that specimens characterized by very wavy grain shows a high damping capacity of frequency range between 33.33 to 50Hz, unlike specimens of common maple which do not have the capacity of frequency selectivity.

  5. Equine acquired multiple acyl-CoA dehydrogenase deficiency (MADD) in 14 horses associated with ingestion of Maple leaves (Acer pseudoplatanus) covered with European tar spot (Rhytisma acerinum)

    NARCIS (Netherlands)

    van der Kolk, J. H.; Wijnberg, I. D.; Westermann, C. M.; Dorland, L.; de Sain-van der Velden, M. G. M.; Kranenburg, L. C.; Duran, M.; Dijkstra, J. A.; van der Lugt, J. J.; Wanders, R. J. A.; Gruys, E.

    2010-01-01

    This case-series describes fourteen horses suspected of equine acquired multiple acyl-CoA dehydrogenase deficiency (MADD) also known as atypical myopathy of which seven cases were confirmed biochemically with all horses having had access to leaves of the Maple tree (Acer pseudoplatanus) covered with

  6. Seasonal changes in the degree of symplasmic continuity between the cells of cambial region of Acer pseudoplatanus and Ulmus minor

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    Katarzyna Sokołowska

    2011-01-01

    Full Text Available The presence of symplasmic isolation and symplasmic continuity which are functional aspects of cell-to-cell communication, had been studied in cambium of Acer pseudoplatanus and Ulmus minor, with hope that uniqueness of this meristem, exemplified by its morphology and seasonal variations in its activity is also manifested in differences in the efficiency of communication between cambial cells during the year. The degree of symplasmic continuity was estimated by loading the fluorescent symplasmic tracer to the stem and following its distribution in a population of cambial cells observed on tangential, transverse and radial sections. In active cambium the tracer did not enter the rays. This suggested that the ray and fusiform cells, growing and dividing intensively at different rates were specifically isolated from each other. In the state of dormancy the tracer was present also in the rays implying continuity between the two types of cambial cells. Temporal restriction in tracer spreading from secondary xylem to cambial region was observed on transverse sections in both physiological states of the meristem. Higher degree of symplasmic isolation in active cambium is, most probably, associated with functional distinctiveness of ray and fusiform cells. We hypothesize further that the symplasmic continuity in dormant cambium results from the open conformation states of plasmodesmata, because the energy costs of these states are low. It is reasonable strategy when cambial cells do not divide and maintenance of their functional individuality is not necessary.

  7. Root vitality of Fagus sylvatica L., Quercus petraea Liebl. and Acer pseudoplatanus L. in mature mixed forest stand

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    Grygoruk Dorota

    2016-06-01

    Full Text Available The main task of the present study was to investigate the root vitality of common beech Fagus sylvatica L., sessile oak Quercus petraea Liebl. and sycamore maple Acer pseudoplatanus L. in the optimal g rowth conditions in south-western Poland. The study was carried out in 130-year-old mixed stand located within natural range of studied tree species. The density of roots (g/100 cm3 of soil and biomass of fine roots (g/m2 in topsoil layers (0-5 cm, 5-15 cm were determined in the tree biogroups of the same species. The mean total root density ranged from 0.248 to 0.417 g/100 cm3 in the 0-5 cm soil layer, and it decreased in the deeper soil layer (5-15 cm. There were found no statistically significant differences of total root densities between tree biogroups in topsoil layers. Diversity of fine root biomass was comparable in the tree biogroups (H’ = 1.5, but common beech showed more intensive growth of fine roots in the topsoil 0-15 cm when compared to sessile oak and sycamore maple. The results of the study point out the stability of the multi-species structure of the mixed stand studied, and consequently - the ability of beech, sessile oak and sycamore maple trees to coexist in the mixed stands - in the area of natural range of these species.

  8. Food-chain transfer of zinc from contaminated Urtica dioica and Acer pseudoplatanus L. to the aphids Microlophium carnosum and Drepanosiphum platanoidis Schrank

    Energy Technology Data Exchange (ETDEWEB)

    Sinnett, Danielle, E-mail: danielle.sinnett@forestry.gsi.gov.u [Centre for Forestry and Climate Change, Forest Research, Alice Holt Lodge, Farnham, Surrey GU10 4LH (United Kingdom); Department of Soil Science, School of Human and Environmental Sciences, University of Reading, Whiteknights, Reading RG6 6DW (United Kingdom); Hutchings, Tony R., E-mail: tony.hutchings@forestry.gsi.gov.u [Centre for Forestry and Climate Change, Forest Research, Alice Holt Lodge, Farnham, Surrey GU10 4LH (United Kingdom); Hodson, Mark E., E-mail: m.e.hodson@reading.ac.u [Department of Soil Science, School of Human and Environmental Sciences, University of Reading, Whiteknights, Reading RG6 6DW (United Kingdom)

    2010-01-15

    This study examines the food-chain transfer of Zn from two plant species, Urtica dioica (stinging nettle) and Acer pseudoplatanus (sycamore maple), into their corresponding aphid species, Microlophium carnosum and Drepanosiphum platanoidis. The plants were grown in a hydroponic system using solutions with increasing concentrations of Zn from 0.02 to 41.9 mg Zn/l. Above-ground tissue concentrations in U. dioica and M. carnosum increased with increasing Zn exposure (p < 0.001). Zn concentrations in A. pseudoplatanus also increased with solution concentration from the control to the 9.8 mg Zn/l solution, above which concentrations remained constant. Zn concentrations in both D. platanoidis and the phloem tissue of A. pseudoplatanus were not affected by the Zn concentration in the watering solution. It appears that A. pseudoplatanus was able to limit Zn transport in the phloem, resulting in constant Zn exposure to the aphids. Zn concentrations in D. platanoidis were around three times those in M. carnosum. - Concentrations of Zn in two aphid species are dependant on species and exposure.

  9. Food-chain transfer of zinc from contaminated Urtica dioica and Acer pseudoplatanus L. to the aphids Microlophium carnosum and Drepanosiphum platanoidis Schrank

    International Nuclear Information System (INIS)

    Sinnett, Danielle; Hutchings, Tony R.; Hodson, Mark E.

    2010-01-01

    This study examines the food-chain transfer of Zn from two plant species, Urtica dioica (stinging nettle) and Acer pseudoplatanus (sycamore maple), into their corresponding aphid species, Microlophium carnosum and Drepanosiphum platanoidis. The plants were grown in a hydroponic system using solutions with increasing concentrations of Zn from 0.02 to 41.9 mg Zn/l. Above-ground tissue concentrations in U. dioica and M. carnosum increased with increasing Zn exposure (p < 0.001). Zn concentrations in A. pseudoplatanus also increased with solution concentration from the control to the 9.8 mg Zn/l solution, above which concentrations remained constant. Zn concentrations in both D. platanoidis and the phloem tissue of A. pseudoplatanus were not affected by the Zn concentration in the watering solution. It appears that A. pseudoplatanus was able to limit Zn transport in the phloem, resulting in constant Zn exposure to the aphids. Zn concentrations in D. platanoidis were around three times those in M. carnosum. - Concentrations of Zn in two aphid species are dependant on species and exposure.

  10. Samaras and seedlings of Acer pseudoplatanus are potential sources of hypoglycin A intoxication in atypical myopathy without necessarily inducing clinical signs.

    Science.gov (United States)

    Baise, E; Habyarimana, J A; Amory, H; Boemer, F; Douny, C; Gustin, P; Marcillaud-Pitel, C; Patarin, F; Weber, M; Votion, D-M

    2016-07-01

    Ingestion of sycamore seeds (Acer pseudoplatanus) is the likely source of hypoglycin A in atypical myopathy (AM) but ingestion of seedlings in spring might also contribute to intoxication. To test for hypoglycin A in seeds and seedlings collected on pastures where AM cases were reported and compare its concentration in serum of affected and healthy horses. Field investigation of clinical cases. Whenever present, samaras (the winged nuts that each contain one seed) and/or seedlings were collected from pastures of 8 AM cases and 5 unaffected horses from different premises. Two AM cases were each co-grazing with an apparently healthy horse. Acylcarnitines and hypoglycin A were quantified in blood samples of all horses involved in the study. Hypoglycin A was detected in serum of AM (5.47 ± 1.60 μmol/l) but not in healthy controls pasturing where A. pseudoplatanus trees were not present. However, hypoglycin A was detected at high concentrations (7.98 μmol/l) in serum of a clinically healthy horse grazing a pasture with seedlings and samaras and also in the 2 healthy horses co-grazing with AM cases (0.43 ± 0.59 μmol/l). Hypoglycin A was detected in all samples of seeds and spring seedlings of A. pseudoplatanus. Atypical myopathy can be associated with the ingestion of sycamore samaras and also ingestion of seedlings. Hypoglycin A can be detected in the blood of horses with no detectable clinical signs at pasture in which there is A. pseudoplatanus. Determination of hypoglycin A concentration in blood is useful for screening for exposure in suspected cases of AM. © 2015 EVJ Ltd.

  11. Xylan synthetase activity in differentiated xylem cells of sycamore trees (Acer pseudoplatanus).

    Science.gov (United States)

    Dalessandro, G; Northcote, D H

    1981-01-01

    Particulate enzymic preparations obtained from homogenates of differentiated xylem cells isolated from sycamore trees, catalyzed the formation of a radioactive xylan in the presence of UDP-D-[U-(14)C]xylose as substrate. The synthesized xylan was not dialyzable through Visking cellophane tubing. Successive extraction with cold water, hot water and 5% NaOH dissolved respectively 15, 5 and 80% of the radioactive polymer. Complete acid hydrolysis of the water-insoluble polysaccharide synthesized from UDP-D-[U-(14)C]xylose released all the radioactivity as xylose. β-1,4-Xylodextrins, degree of polymerization 2, 3, 4, 5 and 6, were obtained by partial acid hydrolysis (fuming HCl or 0.1 M HCl) of radioactive xylan. The polymer was hydrolysed to xylose, xylobiose and xylotriose by Driselase which contains 1,4-β xylanase activities. Methylation and then hydrolysis of the xylan released two methylated sugars which were identified as di-O-methyl[(14)C]xylose and tri-O-methyl-[(14)C]xylose, suggesting a 1→4-linked polymer. The linkage was confirmed by periodate oxidation studies. The apparent Km value of the synthetase for UDP-D-xylose was 0.4 mM. Xylan synthetase activity was not potentiated in the presence of a detergent. The enzymic activity was stimulated by Mg(2+) and Mn(2+) ions, although EDTA in the range of concentrations between 0.01 and 1 mM did not affect the reaction rate. It appears that the xylan synthetase system associated with membranes obtained from differentiated xylem cells of sycamore trees may serve for catalyzing the in vivo synthesis of the xylan main chain during the biogenesis of the plant cell wall.

  12. Detection of hypoglycin A in the seeds of sycamore (Acer pseudoplatanus) and box elder (A. negundo) in New Zealand; the toxin associated with cases of equine atypical myopathy.

    Science.gov (United States)

    McKenzie, R K; Hill, F I; Habyarimana, J A; Boemer, F; Votion, D M

    2016-05-01

    During April and May 2014 four horses aged between 5 months and 9 years, located in the Canterbury, Marlborough and Southland regions, presented with a variety of clinical signs including recumbency, stiffness, lethargy, dehydration, depression, and myoglobinuria suggestive of acute muscle damage. Two horses were subjected to euthanasia and two recovered. In all cases seeds of sycamore maple (Acer pseudoplatanus) or box elder (A. negundo) were present in the area where the horse had been grazing. The samaras (seeds) of some Acer spp. may contain hypoglycin A, that has been associated with cases of atypical myopathy in Europe and North America. To determine if hypoglycin A is present in the samaras of Acer spp. in New Zealand, samples were collected from trees throughout the country that were associated with historical and/or current cases of atypical myopathy, and analysed for hypoglycin A. Serum samples from the four cases and four unaffected horses were analysed for the presence of hypoglycin A, profiles of acylcarnitines (the definitive diagnosis for atypical myopathy) and activities of creatine kinase and aspartate aminotransferase.Markedly elevated serum activities of creatine kinase and aspartate aminotransferase, and increased concentrations of selected acylcarnitines were found in the case horses. Hypoglycin A was detected in the serum of those horses but not in the healthy controls. Hypoglycin A was detected in 10/15 samples of samaras from sycamore maple and box elder from throughout New Zealand. Cases of atypical myopathy were diagnosed on properties where samaras containing hypoglycin A were also found. Sycamore and box elder trees in New Zealand are a source of hypoglycin A associated with the development of atypical myopathy. If pastured horses present with clinical and biochemical signs of severe muscle damage then the environment should be checked for the presence of these trees. Horses should be prevented from grazing samaras from Acer spp. in the

  13. The acropetal effects of indole-3-acetic acid in isolated shoot segments of Acer pseudoplatanus L. II. Possible regulation by a vectorial fieid of auxin waves

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    Jacek A. Adamczyk

    2014-01-01

    Full Text Available The acropetal effects of auxin on elongation of axillary buds and on modulation of the wave-like pattern of basipetal efflux of natural auxin to agar from Acer pseudoplatanus L. shoots were studied. When synthetic IAA was applied to cut surfaces of one of two branches the elongation growth of buds situated on the opposite branch was retarded, suggesting regulation independent of the direct action of the molecules of the applied IAA. Oscillations in basipetal transport of natural auxin along the stem segments were observed corroborating the results of other authors using different tree species. Apical application of synthetic IAA for 1 hour to the lateral branch caused a phase shift of the wave-like pattern of basipetal efflux of natural auxin, when the stem segment above the treated branch was sectioned. The same effect was observed evoked by the laterally growing branch which is interpreted as an effect of natural auxin produced by the actively growing shoot. These modulations could be propagated acropetally at a rate excluding direct action of auxin molecules at the sites of measurement. The results seem to corroborate the hypothesis suggesting that auxin is involved in acropetal regulation of shoot apex growth through its effect upon modulation of the vectorial field which arises when the auxin-waves translocate in cambium.

  14. Competition for nitrogen between Fagus sylvatica and Acer pseudoplatanus seedlings depends on soil nitrogen availability

    Science.gov (United States)

    Li, Xiuyuan; Rennenberg, Heinz; Simon, Judy

    2015-01-01

    Competition for nitrogen (N), particularly in resource-limited habitats, might be avoided by different N acquisition strategies of plants. In our study, we investigated whether slow-growing European beech and fast-growing sycamore maple seedlings avoid competition for growth-limiting N by different N uptake patterns and the potential alteration by soil N availability in a microcosm experiment. We quantified growth and biomass indices, 15N uptake capacity and N pools in the fine roots. Overall, growth indices, N acquisition and N pools in the fine roots were influenced by species-specific competition depending on soil N availability. With inter-specific competition, growth of sycamore maple reduced regardless of soil N supply, whereas beech only showed reduced growth when N was limited. Both species responded to inter-specific competition by alteration of N pools in the fine roots; however, sycamore maple showed a stronger response compared to beech for almost all N pools in roots, except for structural N at low soil N availability. Beech generally preferred organic N acquisition while sycamore maple took up more inorganic N. Furthermore, with inter-specific competition, beech had an enhanced organic N uptake capacity, while in sycamore maple inorganic N uptake capacity was impaired by the presence of beech. Although sycamore maple could tolerate the suboptimal conditions at the cost of reduced growth, our study indicates its reduced competitive ability for N compared to beech. PMID:25983738

  15. Polyploidy in Acer rubrum L.

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    John W. Duffield

    1943-01-01

    Acer rubrum L. is a highly polymorphic species occupying a range which includes almost all of the United States east of the prairies, southeastern Canada, and a portion of Newfoundland. The range of habitats occupied is equally impressive. Cytological study of this species was first undertaken by Mottier in 1893, but the first indication of...

  16. Accelerator Center for Energy Research (ACER)

    Data.gov (United States)

    Federal Laboratory Consortium — The Accelerator Center for Energy Research (ACER) exploits radiation chemistry techniques to study chemical reactions (and other phenomena) by subjecting samples to...

  17. Flowering and sex expression in Acer L. : a biosystematic study

    NARCIS (Netherlands)

    Jong, de P.C.

    1976-01-01

    A review and an analysis is given of flowering and sex expression in Acer. The process of sex differentiation was studied in physiological experiments and could be influenced by accelerated flowering and by removal of female.gif flower buds just after bud break. The

  18. Effects of Acer okamotoanum sap on the function of polymorphonuclear neutrophilic leukocytes in vitro and in vivo.

    Science.gov (United States)

    An, Beum-Soo; Kang, Ji-Houn; Yang, Hyun; Yang, Mhan-Pyo; Jeung, Eui-Bae

    2013-02-01

    Sap is a plant fluid that primarily consists of water and small amounts of mineral elements, sugars, hormones and other nutrients. Acer mono (A. mono) is an endemic Korean mono maple which was recently suggested to have health benefits due to its abundant calcium and magnesium ion content. In the present study, we examined the effects of sap from Acer okamotoanum (A. okamotoanum) on the phagocytic response of mouse neutrophils in vivo and rat and canine neutrophils in vitro. We tested the regulation of phagocytic activity, oxidative burst activity (OBA) and the levels of filamentous polymeric actin (F-actin) in the absence and presence of dexamethasone (DEX) in vitro and in vivo. Our results showed that DEX primarily reduced OBA in the mouse neutrophils, and that this was reversed in the presence of the sap. By contrast, the phagocytic activity of the mouse cells was not regulated by either DEX or the sap. Rat and canine polymorphonuclear neutrophilic leukocytes (PMNs) responded in vitro to the sap in a similar manner by increasing OBA. However, regulation of phagocytic activity by the sap was different between the species. In canine PMNs, phagocytic activity was enhanced by the sap at a high dose, while it did not significantly modulate this activity in rat PMNs. These findings suggest that the sap of A. okamotoanum stimulates neutrophil activity in the mouse, rat and canine by increasing OBA in vivo and in vitro, and thus may have a potential antimicrobial effect in the PMNs of patients with infections.

  19. Volatiles from a Rare Acer spp. Honey Sample from Croatia

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    Igor Jerković

    2010-06-01

    Full Text Available A rare sample of maple (Acer spp. honey from Croatia was analysed. Ultrasonic solvent extraction (USE using: 1 pentane, 2 diethyl ether, 3 a mixture of pentane and diethyl ether (1:2 v/v and 4 dichloromethane as solvents was applied. All the extracts were analysed by GC and GC/MS. The most representative extracts were 3 and 4. Syringaldehyde was the most striking compound, being dominant in the extracts 2, 3 and 4 with percentages 34.5%, 33.1% and 35.9%, respectively. In comparison to USE results of other single Croatian tree honey samples (Robinia pseudoacacia L. nectar honey, Salix spp. nectar and honeydew honeys, Quercus frainetto Ten. honeydew as well as Abies alba Mill. and Picea abies L. honeydew and literature data the presence of syringaldehyde, previously identified in maple sap and syrup, can be pointed out as a distinct characteristic of the Acer spp. honey sample. Headspace solid-phase microextraction (HS-SPME combined with GC and GC/MS identified benzaldehyde (16.5%, trans-linalool oxide (20.5% and 2-phenylethanol (14.9% as the major compounds that are common in different honey headspace compositions.

  20. Polymeric microspheres

    Science.gov (United States)

    Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

    2004-04-13

    The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

  1. Seasonality of cavitation and frost fatigue in Acer mono Maxim.

    Science.gov (United States)

    Zhang, Wen; Feng, Feng; Tyree, Melvin T

    2017-12-08

    Although cavitation is common in plants, it is unknown whether the cavitation resistance of xylem is seasonally constant or variable. We tested the changes in cavitation resistance of Acer mono before and after a controlled cavitation-refilling and freeze-thaw cycles for a whole year. Cavitation resistance was determined from 'vulnerability curves' showing the percent loss of conductivity versus xylem tension. Cavitation fatigue was defined as a reduction of cavitation resistance following a cavitation-refilling cycle, whereas frost fatigue was caused by a freeze-thaw cycle. A. mono developed seasonal changes in native embolisms; values were relatively high during winter but relatively low and constant throughout the growing season. Cavitation fatigue occurred and changed seasonally during the 12-month cycle; the greatest fatigue response occurred during summer and the weakest during winter, and the transitions occurred during spring and autumn. A. mono was highly resistant to frost damage during the relatively mild winter months; however, a quite different situation occurred during the growing season, as the seasonal trend of frost fatigue was strikingly similar to that of cavitation fatigue. Seasonality changes in cavitation resistance may be caused by seasonal changes in the mechanical properties of the pit membranes. © 2017 John Wiley & Sons Ltd.

  2. Monitoring the health of sugar maple, Acer saccharum

    Science.gov (United States)

    Carlson, Martha

    The sugar maple, Acer saccharum, is projected to decline and die in 88 to 100 percent of its current range in the United States. An iconic symbol of the northeastern temperate forest and a dominant species in this forest, the sugar maple is identified as the most sensitive tree in its ecosystem to rising temperatures and a warming climate. This study measures the health of sugar maples on 12 privately owned forests and at three schools in New Hampshire. Laboratory quantitative analyses of leaves, buds and sap as well as qualitative measures of leaf and bud indicate that record high beat in 2012 stressed the sugar maple. The study identifies several laboratory and qualitative tests of health which seem most sensitive and capable of identifying stress early when intervention in forest management or public policy change might counter decline of the species. The study presents evidence of an unusual atmospheric pollution event which defoliated sugar maples in 2010. The study examines the work of citizen scientists in Forest Watch, a K-12 school program in which students monitor the impacts of ozone on white pine, Pinus strobus, another keystone species in New Hampshire's forest. Finally, the study examines three simple measurements of bud, leaf and the tree's acclimation to light. The findings of these tests illuminate findings in the first study. And they present examples of what citizen scientists might contribute to long-term monitoring of maples. A partnership between science and citizens is proposed to begin long-term monitoring and to report on the health of sugar maples.

  3. Brazilian adaptation of the Addenbrooke's Cognitive Examination-Revised (ACE-R

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    Viviane Amaral Carvalho

    Full Text Available Abstract The Addenbrooke's Cognitive Examination-Revised (ACE-R is a highly sensitive and specific tool for the detection of mild dementia. It is particularly useful in differentiating Alzheimer's disease from frontotemporal dementia. While the first version of the test battery has been adapted in many countries, its revised version has not, probably because it was published very recently. Objective: To translate and adapt the ACE-R for use in the Brazilian population. Methods: Two independent translations were made from English into Portuguese, followed by two independent back-translations. Few adaptations in accordance to the Brazilian culture and language were made and a first version of the instrument produced. This former version of the ACE-R was administered to 21 cognitively healthy subjects aged 60 years or more, with different educational levels. Results: The mean age of the studied sample of healthy elderly was 75.4 years (ranging from 60 to 89 years. Small additional modifications were necessary after the evaluation of the first ten subjects in order to improve comprehension of the test. The final Portuguese version of the ACE-R was produced and was found to be well understood by the remaining 11 subjects, taking an average of 15 minutes to be administered. Conclusions: The Brazilian version of the ACE-R proved to be a promising cognitive instrument for testing both in research and clinical settings. With this regard, additional studies are currently being carried out in our unit in order to investigate the diagnostic properties of the ACE-R in our milieu.

  4. Traditional uses, phytochemistry, and pharmacology of the genus Acer (maple): A review.

    Science.gov (United States)

    Bi, Wu; Gao, Ying; Shen, Jie; He, Chunnian; Liu, Haibo; Peng, Yong; Zhang, Chunhong; Xiao, Peigen

    2016-08-02

    The genus Acer (Aceraceae), commonly known as maple, comprises approximately 129 species that primarily grow in the northern hemisphere, especially in the temperate regions of East Asia, eastern North America, and Europe. These plants have been traditionally used to treat a wide range of diseases in East Asia and North America. Moreover, clinical studies have shown that medicinal plants belonging to Acer are highly effective in the treatment of rheumatism, bruises, hepatic disorders, eye disease, and pain, and in detoxification. This review provides a systematic and constructive overview of the traditional uses, chemical constituents, and pharmacological activities of plants of the genus Acer. This review is based on a literature study of scientific journals and books from libraries and electronic sources such as SciFinder, ScienceDirect, Springer, PubMed, CNKI, Google Scholar, Baidu Scholar, and Web of Science. The literature in this review related to chemical constituents and pharmacological activities dates from 1922 to the end of October 2015. Furthermore, ethnopharmacological information on this genus was obtained from libraries and herbaria in China and USA. In traditional medicine, 40 species, 11 subspecies, and one varieta of the genus Acer are known to exhibit a broad spectrum of biological activities. To date, 331 compounds have been identified from 34 species of the genus Acer, including flavonoids, tannins, phenylpropanoids, diarylheptanoids, terpenoids, benzoic acid derivatives, and several other types of compounds, such as phenylethanoid glycosides and alkaloids. Preliminary pharmacological studies have shown that the extracts and compounds isolated from this genus exhibit a broad spectrum of biological activities such as antioxidant, antitumor, anti-inflammatory, antidiabetic, hepatoprotective, and antiobesity activities, as well as promoting osteoblast differentiation. To date, reports on the toxicity of Acer species to humans are very limited, and

  5. Condensation Polymerization

    Indian Academy of Sciences (India)

    building blocks, is essentially the process of polycondensation or step-growth polymerization. Before we leave this LEGO-style discussion, I would leave you with two alternate scenarios; one is to use building blocks bearing two sockets and two balls, as de- picted in the figure, and the other is to use blocks that contain two.

  6. Condensation Polymerization

    Indian Academy of Sciences (India)

    At first, let us begin by treating molecules as LEGO-type building blocks with certain strict rules for linking them; a ball can readily fit with a socket, ... is essentially the process of polycondensation or step-growth polymerization. Before we leave this LEGO-style discussion, I would leave you with two alternate scenarios; one is.

  7. ACER Mathematics Profile Series: Number Test. (Test Booklet, Answer and Record Sheet, Score Key, and Teachers Handbook).

    Science.gov (United States)

    Cornish, Greg; Wines, Robin

    The Number Test of the ACER Mathematics Profile Series, contains 30 items, for each of three suggested grade levels: 7-8, 8-9, and 9-10. Raw scores on all tests in the ACER Mathematics Profile Series (Number, Operations, Space and Measurement) are converted to a common scale called MAPS, a major feature of the Series. Based on the Rasch Model,…

  8. Assessment of genetic diversity and variation of acer mono max seedlings after spaceflight

    International Nuclear Information System (INIS)

    Long, C.; Li, Y.; Zhang, Y.; Yang, M.

    2015-01-01

    Genetic diversity and variation of Acer Mono Maxim seedlings sampled from space-mutated (sm) populations were compared to seedlings from parallel control (ck) ones using molecular markers. RAMP analysis showed that the percentage of polymorphic band, Shannon diversity index and Nei gene diversity index of the space-mutated populations were higher than those of the control ones, which indicated that genetic variation increased after spaceflight in populations of Acer Mono Maxim. By using un-weighted pair group method with arithmetic mean (UPGMA) method, three space-mutated repeats (populations) were clustered together, and control groups clustered separately, which further indicated that there was difference between the space-mutated ones and the control ones, which may be caused by space mutation. Further analysis of genomic inconsistency between the root and leaf samples from the same tree showed that a total variation rate of 6.3% and 1.7% were obtained in ten space-mutated individuals by using RAMP and SSR markers, respectively, however, the variation rate was zero in control ones. It provided that space mutation may be caused the individual variation of Acer Mono Maxim. (author)

  9. Reproduction and vegetative growth in the dioecious shrub Acer barbinerve in temperate forests of Northeast China.

    Science.gov (United States)

    Wang, Juan; Zhang, Chunyu; Gadow, Klaus V; Cheng, Yanxia; Zhao, Xiuhai

    2015-06-01

    Trade-off in dioecious plant. The trade-off between reproduction, vegetative growth and maintenance is a major issue in the life history of an organism and a record of the process which is producing the largest possible number of living offspring by natural selection. Dioecious species afford an excellent opportunity for detecting such possible trade-offs in resource allocation. In this study, we selected the dioecious shrub Acer barbinerve to examine possible trade-offs between reproduction and vegetative growth in both genders at different modular levels during three successive years. Reproductive and vegetative biomass values were assessed during successive years to evaluate their intra-annual and inter-annual trade-offs. These trade-offs were examined at shoot, branch and shrub modular levels in Acer barbinerve shrubs. An intra-annual trade-off was detected at the shoot level for both genders in 2011 and 2012. Both males and females showed a negative correlation between reproduction and vegetative growth, but this was more prominent in males. For the females of the species, inter-annual trade-offs were only found at branch and shrub levels. Slightly negative correlations in females were detected between the reproduction in 2012 and the reproduction in the two previous years. The gender ratio was significantly male biased during the three successive years of our investigation. Females had higher mortality rates in the larger diameter classes, both in 2011 and 2012. This study revealed a clear trade-off between reproduction and vegetative growth in Acer barbinerve, but results varied between males and females. The degree of autonomy of the different modular levels may affect the ability to detect such trade-offs.

  10. Presumptive red maple (Acer rubrum) toxicosis in Grevy's zebra (Equus grevyi).

    Science.gov (United States)

    Weber, M; Miller, R E

    1997-03-01

    Two female Grevy's zebras (Equus grevyi), one juvenile and one adult, were treated for hemolytic anemia. The juvenile survived, but the adult animal, which also had methemoglobinemia, was euthanized after it failed to recover from anesthesia. Significant pathologic findings in the adult zebra included generalized icterus, hemoglobinuric nephrosis, and paracentral hepatic necrosis. Serum titers for known infectious causes of anemia were negative. Examination of the zebra holding areas revealed two hybrid red maple (Acer sp.) trees. There was no known exposure to other hemolytic agents. This is the first report of probable red maple-induced hemolysis in zebra.

  11. Testing hypotheses that link wood anatomy to cavitation resistance and hydraulic conductivity in the genus Acer.

    Science.gov (United States)

    Lens, Frederic; Sperry, John S; Christman, Mairgareth A; Choat, Brendan; Rabaey, David; Jansen, Steven

    2011-05-01

    • Vulnerability to cavitation and conductive efficiency depend on xylem anatomy. We tested a large range of structure-function hypotheses, some for the first time, within a single genus to minimize phylogenetic 'noise' and maximize detection of functionally relevant variation. • This integrative study combined in-depth anatomical observations using light, scanning and transmission electron microscopy of seven Acer taxa, and compared these observations with empirical measures of xylem hydraulics. • Our results reveal a 2 MPa range in species' mean cavitation pressure (MCP). MCP was strongly correlated with intervessel pit structure (membrane thickness and porosity, chamber depth), weakly correlated with pit number per vessel, and not related to pit area per vessel. At the tissue level, there was a strong correlation between MCP and mechanical strength parameters, and some of the first evidence is provided for the functional significance of vessel grouping and thickenings on inner vessel walls. In addition, a strong trade-off was observed between xylem-specific conductivity and MCP. Vessel length and intervessel wall characteristics were implicated in this safety-efficiency trade-off. • Cavitation resistance and hydraulic conductivity in Acer appear to be controlled by a very complex interaction between tissue, vessel network and pit characteristics. © 2010 The Authors. New Phytologist © 2010 New Phytologist Trust.

  12. On merging Acer sections Rubra and Hyptiocarpa: Molecular and morphological evidence

    Directory of Open Access Journals (Sweden)

    AJ Harris

    2017-09-01

    Full Text Available In this study, we expanded Acer sect. Rubra Pax to include A. sect. Hyptiocarpa Fang. Traditionally, section Rubra comprises two iconic species, Acer rubrum Linnaeus (red maple and A. saccharinum Linnaeus (silver maple, of eastern North American forests as well as the rare Japanese montane species, A. pycnanthum K. Koch. Section Hyptiocarpa consists of A. laurinum Hasskarl and A. pinnatinervium Merrill, which occur in subtropical and tropical regions of southwestern China to southeast Asia. Here, we confirm prior phylogenetic results showing the close relationship between sects. Rubra and Hyptiocarpa, and we use scanning electron microscopy to demonstrate that leaves of species within these sections have similar arrangements of cuticular waxes, which account for the silvery color of their abaxial surfaces. We describe that the sections also share labile sex expression; inflorescences that range from compound racemose thyrses, to racemes or umbels and that may have undergone evolutionary reduction; and several features of their fruits, such as seed locules without keels, basal portion of wings straight, acute attachment angle between mericarps, and production of some mericarps that are seedless and partially developed at maturity. Our expansion of sect. Rubra to include sect. Hyptiocarpa better elucidates the biogeographic and evolutionary history of these species. Additionally, we show that A. laurinum and A. pinnatinervium have intergrading morphology and are probably synonymous, but we note that further studies are required to conclude their taxonomic status.

  13. Red Maple (Acer rubrum L.) Growth and Foliar Nutrient Responses to Soil Fertility Level and Water Regime

    Science.gov (United States)

    C. H. Pham; Howard G. Halverson; Gordon M. Heisler

    1978-01-01

    Red maple (Acer rubrum L.) seedlings were grown in a greenhouse using three treatments: two soil horizons, two soil moisture regimes, and three nutrient levels. Fertilization increased growth under moist conditions on the more fertile topsoil. Under dry conditions, fertilization had no effect on growth in subsoil, and slightly increased growth in...

  14. Effect of planting procedures in initial growth of Acer rubrum L. and Fraxinus pennsylvanicum L. in a parking lot

    Science.gov (United States)

    Gordon M. Heisler; Robert E. Schutzki; Robert P. Zisa; Howard G. Halverson; Bruce A. Hamilton

    1982-01-01

    Five-year old red maples, Acer rubrum L. 'October Glory', and green ash, Fraxinus pennsylvanicum L. 'Marshall Seedless', were planted in 8 ft x 8 ft openings in an asphalt parking lot with two planting stocks (bare-root, BR, and balled and burlapped, B&B) and two fertilizer levels (a control and 1.36 kg of...

  15. A Nuclear Ribosomal DNA Phylogeny of Acer Inferred with Maximum Likelihood, Splits Graphs, and Motif Analysis of 606 Sequences

    Directory of Open Access Journals (Sweden)

    Guido W. Grimm

    2006-01-01

    Full Text Available The multi-copy internal transcribed spacer (ITS region of nuclear ribosomal DNA is widely used to infer phylogenetic relationships among closely related taxa. Here we use maximum likelihood (ML and splits graph analyses to extract phylogenetic information from ~ 600 mostly cloned ITS sequences, representing 81 species and subspecies of Acer, and both species of its sister Dipteronia. Additional analyses compared sequence motifs in Acer and several hundred Anacardiaceae, Burseraceae, Meliaceae, Rutaceae, and Sapindaceae ITS sequences in GenBank. We also assessed the effects of using smaller data sets of consensus sequences with ambiguity coding (accounting for within-species variation instead of the full (partly redundant original sequences. Neighbor-nets and bipartition networks were used to visualize conflict among character state patterns. Species clusters observed in the trees and networks largely agree with morphology-based classifications; of de Jong’s (1994 16 sections, nine are supported in neighbor-net and bipartition networks, and ten by sequence motifs and the ML tree; of his 19 series, 14 are supported in networks, motifs, and the ML tree. Most nodes had higher bootstrap support with matrices of 105 or 40 consensus sequences than with the original matrix. Within-taxon ITS divergence did not differ between diploid and polyploid Acer, and there was little evidence of differentiated parental ITS haplotypes, suggesting that concerted evolution in Acer acts rapidly.

  16. Analysis of stand basal area development of thinned and unthinned Acer rubrum forests in the upper Great Lakes region, USA

    Science.gov (United States)

    Justin L. Pszwaro; Anthony W. D' Amato; Thomas E. Burk; Matthew B. Russell; Brian J. Palik; Terry F. Strong

    2016-01-01

    Red maple (Acer rubrum L.), historically a common but not abundant tree species in North America, has increased in abundance throughout its range over the last several decades; however, it has received little attention in growth and yield studies. The objectives of this study were to (i) evaluate the effects of stocking level and stand density on...

  17. Carbohydrate reserves in Acer saccharum trees damaged during the January 1998 ice storm in northern New York

    Science.gov (United States)

    B.L. Wong; L.J. Staats; A.S. Burfeind; K.L. Baggett; A.H. Rye; A.H. Rye

    2005-01-01

    To assess the effect of the ice storm of January 1998 on sugar maple (Acer saccharum Marsh.) tree health, starch, and soluble sugars in twigs from two damaged sugarbushes (younger: trees 50-100 years old, and older: trees approximately 200 years old) in northern New York were measured throughout the leafless phase (September 1998 - May 1999). Trees severely damaged by...

  18. Morphometric characteristics of the leaves of Greek maple (Acer heldreichii Orph in central Serbia

    Directory of Open Access Journals (Sweden)

    Perović Marko

    2007-01-01

    Full Text Available The taxonomic characteristics of Greek maple (Acer heldreichii Orph were studied based on the analysis of leaf characteristics, by comparative-morphological method. The study was performed at three localities in central Serbia: Goč, Jastrebac and Rudnik. 30 normally developed trees were selected per each locality, and 30 leaves were selected from each tree for the analysis. The study includes 8 measured and 15 derived characteristics of leaves. The study results were statistically processed by correlation analysis, analysis of variance and cluster-analysis. It is concluded that there are two varieties, var. heldreichii and var. macropterum. Four forms are set aside in the variety macropterum: f. typicum f. dissectum, f. Equiloba and f. rotundiloba. The populations are relatively homogeneous, and both varieties occur at all three localities in significant numbers.

  19. Chemical synthesis, redox transformation, and identification of sonnerphenolic C, an antioxidant in Acer nikoense.

    Science.gov (United States)

    Iwadate, Takehiro; Nihei, Ken-Ichi

    2017-04-15

    Sonnerphenolic C (3), which was predicted in a redox product of epirhododendrin (1) isolated from Acer nikoense, was synthesized for the first time via the epimeric separation of benzylidene acetal intermediates as a key step. From a similar synthetic route, 1 was obtained concisely. As a result of their antioxidative evaluation, only 3 revealed potent activity. The redox transformation of 1 into 3 was achieved in the presence of tyrosinase and vitamin C. Moreover, 3 was identified in the decoction of A. nikoense by HPLC analysis with the effective use of synthesized 3. Thus, a novel naturally occurring antioxidant 3 was developed through the sequential flow including redox prediction, chemical synthesis, evaluation of the activity, and identification as the natural product. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Enfermedad pulmonar por amianto en trabajadores de acería

    Directory of Open Access Journals (Sweden)

    Rita Zurbriggen

    2013-06-01

    Full Text Available Las enfermedades relacionadas al amianto se producen por la inhalación de fibras de asbestos en su variedad crisotilo o amianto blanco. A pesar de que en la Argentina la prohibición data del año 2003, existen numerosas industrias donde se sigue trabajando con este mineral, entre ellas las metalúrgicas y acerías. Actualmente se conoce la alta patogenicidad de este material, por lo que en muchos países existen programas de seguimiento de los trabajadores expuestos. Se describen las características generales y manifestaciones clínicas pulmonares de 27 pacientes que trabajaron en una gran acería de América del Sur. El diagnóstico de amiantopatías se realizó mediante historia clínica laboral, antecedente de exposición al amianto, estudios complementarios de función pulmonar e imágenes del tórax. Se analizaron la fuente de exposición (laboral, doméstica y ambiental, tiempo de exposición y período de latencia en los pacientes de los cuales se detectó enfermedad relacionada. Los antecedentes de tabaquismo fueron tenidos en cuenta para el análisis. En 22 pacientes se presentaron patologías benignas (81.4%, 16 de ellos tenían lesiones exclusivamente pleurales y otros 6 asbestosis. Las patologías malignas se presentaron en 5 pacientes (18.5%, en 4 fueron mesoteliomas y en uno carcinoma pulmonar. El problema de la exposición al amianto tiene vigencia actual. De ahí la necesidad de un programa de vigilancia en trabajadores expuestos al amianto actualmente o en el pasado, para detectar, notificar, registrar e investigar las características de estas patologías.

  1. Disseny, construcció i manteniment de paviments industrials de formigó armats amb fibres d’acer

    OpenAIRE

    Villaverde González, José María; Moreno Moreno, Hugo

    2008-01-01

    En el present projecte s’ha pretès descriure amb detall els avantatges específics del formigó reforçat amb fibres d’acer en la seva utilització com a paviment industrial. Segons això, la primera part d’aquest document s’estructura de la següent manera: En primer lloc, es fa una comparació amb els sistemes convencionals d’execució de paviments on, inicialment, es planteja el procés de disseny d’un paviment de formigó reforçat amb fibres d’acer, tant des del punt de vista del càl...

  2. New forms of maples (ACER L., Aceraceae cultivated at Peter the Great Botanic Garden (ST. Petersburg, Russia

    Directory of Open Access Journals (Sweden)

    Firsov Gennadii

    2015-12-01

    Full Text Available The article contains description of two new maple forms - Acer miyabei Maxim. f. suberosum Byalt et Firsov forma nova (Aceraceae and Acer saccharinum L. f. variifolium Byalt et Firsov forma nova – cultivated at Peter the Great Botanic Garden of the Komarov Botanical Institute RAS in St. Petersburg, Russia. The article contains a brief history of the introduction of A. miyabei Maxim. and A. saccharinum L., information about the origin of the planting material in the park of the botanical garden of RAS, basic differences between the new forms and similar taxa (incl. Latin diagnoses, as well as data about standard samples and their storage. The article has color photos of the alive plants located in the botanical garden of RAS. Both maple forms are very decorative and appear to be very useful for a large-scale implementation in the urban landscape planting.

  3. Phenotypic variability of plant leaves of Acer genus, introduced into steppe zone of Ukraine

    Directory of Open Access Journals (Sweden)

    I. O. Zaitseva

    2014-10-01

    Full Text Available This paper deals with studying of the patterns of ecological adaptation of wood species of Acer L. genus during their introduction into steppe zone of Ukraine. Hydrothermal conditions of the growing season in steppe zone of Ukraine are particularly unfavorable for tree and shrubbery plantings, comprising both native and introduced species. In the course of plants’ introduction, adaptive changes occur; such changes represent the spectrum of phenotypic implementation of the definite genotype under the influence of new environmental conditions. Stress environment of the region of introduction leads to occurrence of a great variety of phenotypic forms, as the different variants of genotype implementation. Studying of phenotypic variability gives an opportunity to determine the capacity to adaptation of introduced species and ways of adaptive reactions in new conditions of living. Therefore, objective of the work consists in studying of the processes of differentiation of morphological characters in species of Acer genus introduced in the regions of steppe zone with varying intensity of hydrothermal factors. Studies were carried out in the central and south-eastern steppe regions, as well as in the south of steppe zone in the coastal and continental areas. Subjects of research were 9 species of maples, differing by their botanic and geographic origin and by the degree of drought resistance in the steppe zone of Ukraine. Patterns of variability of morphostructural characters of leaves were determined by the indicator of specific weight of leaves which was calculated as a ratio of weight of dry laminas to their area (mg/cm2. Following the results of study, it was found that adaptation of maples to xerothermic factors of the environment is connected with changing of the ratio of groups of character variation and their contribution into total sample. Direct relationship is established between the probability density of expression (phenotypic

  4. Indirect approach to C-3 branched 1,2-cis-glycofuranosides: synthesis of aceric acid glycoside analogues.

    Science.gov (United States)

    de Oliveira, Marcelo T; Hughes, David L; Nepogodiev, Sergey A; Field, Robert A

    2008-02-04

    Aceric acid (3-C-carboxy-5-deoxy-alpha-l-xylofuranose) residues are present in pectic polysaccharide rhamnogalacturonan II (RG II) in the form of synthetically challenging 1,2-cis-glycofuranosides. To access synthetic fragments of RG II incorporating aceric acid, a four-step procedure based on C-2 epimerisation of initially prepared 1,2-trans-glycofuranoside was developed. Readily available derivatives of branched-chain l-lyxofuranose bearing a 3-C-vinyl group as a masked 3-C-carboxyl group were investigated as potential precursors of aceric acid units. In the first step of the procedure, installation of a participating group at C-2 of the furanose ring ensured stereocontrol of the O-glycosylation, which was carried out with the thioglycoside of 2-O-acetyl-3,5-di-O-benzyl-3-C-vinyl-L-lyxofuranose. After the glycosylation step, the 2-O-acetyl group was removed, the free 2-OH group was oxidised and the resulting ketone was finally reduced to form the C-3-vinyl-L-xylofuranoside. The use of L-Selectride in the key reduction reaction was essential to achieve the required stereoselectivity to generate 1,2-cis-furanoside.

  5. Polymeric Membrane Reactors

    OpenAIRE

    José M. Sousa; Luís M. Madeira; João C. Santos; Adélio Mendes

    2008-01-01

    The aim of this chapter is the study of membrane reactors with polymeric membranes, particularly catalytic polymeric membranes. After an introduction where the main advantages and disadvantages of the use of polymeric membranes are summarised, a review of the main areas where they have been applied, integrated in chemical reactors, is presented. This excludes the field of bio-membranes processes, which is analysed in a specific chapter of this book. Particular attention is then given to model...

  6. Polymerization Using Phosphazene Bases

    KAUST Repository

    Zhao, Junpeng

    2015-09-01

    In the recent rise of metal-free polymerization techniques, organic phosphazene superbases have shown their remarkable strength as promoter/catalyst for the anionic polymerization of various types of monomers. Generally, the complexation of phosphazene base with the counterion (proton or lithium cation) significantly improves the nucleophilicity of the initiator/chain end resulting in highly enhanced polymerization rates, as compared with conventional metalbased initiating systems. In this chapter, the general features of phosphazenepromoted/catalyzed polymerizations and the applications in macromolecular engineering (synthesis of functionalized polymers, block copolymers, and macromolecular architectures) are discussed with challenges and perspectives being pointed out.

  7. Phenotypic plasticity of leaf shape along a temperature gradient in Acer rubrum.

    Directory of Open Access Journals (Sweden)

    Dana L Royer

    2009-10-01

    Full Text Available Both phenotypic plasticity and genetic determination can be important for understanding how plants respond to environmental change. However, little is known about the plastic response of leaf teeth and leaf dissection to temperature. This gap is critical because these leaf traits are commonly used to reconstruct paleoclimate from fossils, and such studies tacitly assume that traits measured from fossils reflect the environment at the time of their deposition, even during periods of rapid climate change. We measured leaf size and shape in Acer rubrum derived from four seed sources with a broad temperature range and grown for two years in two gardens with contrasting climates (Rhode Island and Florida. Leaves in the Rhode Island garden have more teeth and are more highly dissected than leaves in Florida from the same seed source. Plasticity in these variables accounts for at least 6-19% of the total variance, while genetic differences among ecotypes probably account for at most 69-87%. This study highlights the role of phenotypic plasticity in leaf-climate relationships. We suggest that variables related to tooth count and leaf dissection in A. rubrum can respond quickly to climate change, which increases confidence in paleoclimate methods that use these variables.

  8. Proteomic analysis of embryogenesis and the acquisition of seed dormancy in Norway maple (Acer platanoides L.).

    Science.gov (United States)

    Staszak, Aleksandra Maria; Pawłowski, Tomasz Andrzej

    2014-06-17

    The proteome of zygotic embryos of Acer platanoides L. was analyzed via high-resolution 2D-SDS-PAGE and MS/MS in order to: (1) identify significant physiological processes associated with embryo development; and (2) identify changes in the proteome of the embryo associated with the acquisition of seed dormancy. Seventeen spots were identified as associated with morphogenesis at 10 to 13 weeks after flowering (WAF). Thirty-three spots were associated with maturation of the embryo at 14 to 22 WAF. The greatest changes in protein abundance occurred at 22 WAF, when seeds become fully mature. Overall, the stage of morphogenesis was characterized by changes in the abundance of proteins (tubulins and actin) associated with the growth and development of the embryo. Enzymes related to energy supply were especially elevated, most likely due to the energy demand associated with rapid growth and cell division. The stage of maturation is crucial to the establishment of seed dormancy and is associated with a higher abundance of proteins involved in genetic information processing, energy and carbon metabolism and cellular and antioxidant processes. Results indicated that a glycine-rich RNA-binding protein and proteasome proteins may be directly involved in dormancy acquisition control, and future studies are warranted to verify this association.

  9. [Effects of benthic macro-invertebrate on decomposition of Acer buergerianum leaf litter in streams].

    Science.gov (United States)

    Jiang, Li-Hong; Wang, Bei-Xin; Chen, Ai-Qing; Lan, Ce-Jie

    2009-05-01

    By using composite mesh bag method, the effects of benthic macro-invertebrate in an undisturbed stream and an ecologically restored stream on the decomposition process of Acer buergerianum leaf litter from the Purple Mountain of Nanjing in winter were studied. After 112 days of decomposition, the remaining rate of A. buergerianum leaf litter based on ash-free dry mass was 31-62%, and the decomposition rate followed a declined exponential equation (P leaf litter was 0.0064 d(-1) and 0.0030 d(-1); while in the still water of the streams, it was 0.0016 d(-1) and 0. 0018 d(-1), respectively. The abundance and biomass of benthic macro-invertebrate were significantly higher in the flowing water of undisturbed stream than in that of ecologically restored stream (P Shredders (mainly Asellus sp.) had the highest abundance (70.4%) in the flowing water of undisturbed stream, while filterers (mainly Tanytarsus sp.) were dominant (37.8%) in the flowing water of ecologically restored stream. The decomposition rate of the leaf litter was significantly correlated with the richness and abundance of shredder species in flowing water (P shredders, suggesting that the decomposition of A. buergerianum leaf litter in streams in winter was more dependent on the richness and abundance of shredders.

  10. Step-Growth Polymerization.

    Science.gov (United States)

    Stille, J. K.

    1981-01-01

    Following a comparison of chain-growth and step-growth polymerization, focuses on the latter process by describing requirements for high molecular weight, step-growth polymerization kinetics, synthesis and molecular weight distribution of some linear step-growth polymers, and three-dimensional network step-growth polymers. (JN)

  11. Effect of Value Congruence, Brand Distinctiveness, Brand Social, Brand Warmth, and Memorable Brand Experience on Customer-Brand Identification and Brand Loyalty (Case Study: Brand of ACER Laptop)

    Science.gov (United States)

    Susanty, Aries; Tresnaningrum, Aprilia

    2018-02-01

    This study has several purposes. First, this study aims to investigate the effect of consumer-brand value congruence, brand distinctiveness, brand social benefit, brand warmth, and memorable brand experience on customer-brand identification (CBI). We call all of those factors as the antecedent factor of CBI. Second, this study aims to investigate the effect of CBI on customer loyalty. Third, investigate the role of product involvement as a moderating variable of the relationship between brand distinctiveness, brand social benefit, brand warmth, memorable brand experience and CBI. This research used primary data collected through closed questionnaires using a Likert scale of 1 - 5. The total sample size was 273 respondents located in Semarang City who has or has been using Acer Laptop for minimal one year. This research was conducted using Partial Least Square (PLS) method through SmartPLS 3.0 software. The result of data processing indicated that all of the antecedent factors of CBI have the positive and significant effect on CBI of the user of Acer Laptop. In this case, among the five antecedent factors of CBI, value congruence has the greatest effect on CBI of the user of Acer Laptop. The result of data processing also indicated that CBI has the positive and significant effect on brand loyalty of user of Acer Laptop. This study fails to prove the role of product involvement as a moderating variable of the relationship between brand distinctiveness, brand social benefit, brand warmth, memorable brand experience and CBI of the user of Acer Laptop. Moreover, based on the result of hypothesis testing, this study gives some recommendation to Acer Laptop to develop or create some features which are match with the value of user of Laptop Acer in Semarang City.

  12. Effect of Value Congruence, Brand Distinctiveness, Brand Social, Brand Warmth, and Memorable Brand Experience on Customer-Brand Identification and Brand Loyalty (Case Study: Brand of ACER Laptop

    Directory of Open Access Journals (Sweden)

    Susanty Aries

    2018-01-01

    Full Text Available This study has several purposes. First, this study aims to investigate the effect of consumer–brand value congruence, brand distinctiveness, brand social benefit, brand warmth, and memorable brand experience on customer-brand identification (CBI. We call all of those factors as the antecedent factor of CBI. Second, this study aims to investigate the effect of CBI on customer loyalty. Third, investigate the role of product involvement as a moderating variable of the relationship between brand distinctiveness, brand social benefit, brand warmth, memorable brand experience and CBI. This research used primary data collected through closed questionnaires using a Likert scale of 1 - 5. The total sample size was 273 respondents located in Semarang City who has or has been using Acer Laptop for minimal one year. This research was conducted using Partial Least Square (PLS method through SmartPLS 3.0 software. The result of data processing indicated that all of the antecedent factors of CBI have the positive and significant effect on CBI of the user of Acer Laptop. In this case, among the five antecedent factors of CBI, value congruence has the greatest effect on CBI of the user of Acer Laptop. The result of data processing also indicated that CBI has the positive and significant effect on brand loyalty of user of Acer Laptop. This study fails to prove the role of product involvement as a moderating variable of the relationship between brand distinctiveness, brand social benefit, brand warmth, memorable brand experience and CBI of the user of Acer Laptop. Moreover, based on the result of hypothesis testing, this study gives some recommendation to Acer Laptop to develop or create some features which are match with the value of user of Laptop Acer in Semarang City.

  13. Applied bioactive polymeric materials

    CERN Document Server

    Carraher, Charles; Foster, Van

    1988-01-01

    The biological and biomedical applications of polymeric materials have increased greatly in the past few years. This book will detail some, but not all, of these recent developments. There would not be enough space in this book to cover, even lightly, all of the major advances that have occurred. Some earlier books and summaries are available by two of this book's Editors (Gebelein & Carraher) and these should be consul ted for additional information. The books are: "Bioactive Polymeric Systems" (Plenum, 1985); "Polymeric Materials In Medication" (Plenum, 1985); "Biological Acti vi ties of Polymers" (American Chemical Society, 1982). Of these three, "Bioacti ve Polymeric Systems" should be the most useful to a person who is new to this field because it only contains review articles written at an introductory level. The present book primarily consists of recent research results and applications, with only a few review or summary articles. Bioactive polymeric materials have existed from the creation of life...

  14. Variation in root wood anatomy

    NARCIS (Netherlands)

    Cutler, D.F.

    1976-01-01

    Variability in the anatomy of root wood of selected specimens particularly Fraxinus excelsior L. and Acer pseudoplatanus L. in the Kew reference microscope slide collection is discussed in relation to generalised statements in the literature on root wood anatomy.

  15. Hallazgo de un endocarpo del genero Acer en niveles del Cretácico superior del embalse de Pedrezuela (Guadalix de la Sierra

    Directory of Open Access Journals (Sweden)

    Lesiak, M. A.

    1996-12-01

    Full Text Available In this paper is described and discussed an endocarp of Acer genus that exhibits a morphology like the living species A. buergerianum Miquel. The fruit was met in the upper part of Cretaceous series from the Pedrezuela barrier of Madrid Community. We propose a new denomination for the plant that contains this endocarp: Acer palaeobuergerianum n. fsp. This name has only taxonomic value. The prefix is give in order to the age and -buergerianum by its similarity with the actual species.Se describe y discute un endocarpo fósil perteneciente al género Acer, encontrado en el Cretácico superior del embalse de Pedrezuela (Madrid. Este fruto muestra una marcada semejanza con los endocarpos de la especie actual Acer buergerianum Miquel. Se propone una nueva denominación, con valor taxonómico, para la planta: Acer palaeobuergerianum n. fsp. El prefijo palaeo sugiere su edad y la denominación - buergerianum su semejanza morfológica con la especie actual.

  16. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor

    2015-01-22

    The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  17. Polymeric coordination compounds

    Indian Academy of Sciences (India)

    Administrator

    Ce(dipic)3Sr(dipicH2)(OH2)3·5H2O (4) (dipicH2 – dipicolinic acid) exhibits 1-D polymeric chain structure, built up of alternating nine coordinate Ce and eight coordinate. Sr polyhedra. The analogous Ce–Ba compound (5) exhibits a polymeric chain built up of nine coordinate Ba units only, arranged in a hexagonal lattice.

  18. Validation of the language component of the Addenbrooke's Cognitive Examination--Revised (ACE-R) as a screening tool for aphasia in stroke patients.

    Science.gov (United States)

    Gaber, Tarek A-Z K; Parsons, Faye; Gautam, Vidushi

    2011-09-01

    Several tests are available for aphasia screening following stroke. However, some of them have shortcomings such as need of specialist knowledge, low sensitivity and/or specificity and lengthy administration time. Our study aims to evaluate the language component of the Addenbrooke's Cognitive Examination--Revised (ACE-R) as a screening tool for aphasia in stroke patients. The language component of ACE-R was administered to consecutive patients admitted to a post-acute stroke unit. Patients who were medically unstable or had a significant history of sensory impairment or mental health issues were excluded. The test was administered by two junior doctors with basic training in ACE-R administration. Patients recruited were also assessed by an experienced speech and language therapist (SLT). The results of the two assessments were documented by a different member of the team and the SLT results were used as the benchmark to calculate the ACE-R language component sensitivity and specificity.   Fifty-nine participants were recruited and 27 of them were women. The mean age was 72 (SD 11.9). Thirty-four participants had left and 11 right hemisphere stroke. Fourteen had bilateral affection. Six participants were left handed. A cut-off value of 22/26 of ACE-R language component showed 100% specificity and 83.1% sensitivity, while a cut-off value of 16/26 had 88.2% specificity and 100% sensitivity. Our results suggest that the language component of ACE-R has a satisfactory sensitivity and specificity compared with other screening tests used in strokes. It is easy to administer and free to use. © 2010 The Authors. Australasian Journal on Ageing © 2010 ACOTA.

  19. Plasma polymerization by Softplasma

    DEFF Research Database (Denmark)

    Jiang, J.; Wu, Zhenning; Benter, Maike

    2008-01-01

    In the late 19th century, the first depositions - known today as plasma polymers, were reported. In the last century, more and more research has been put into plasma polymers. Many different deposition systems have been developed. [1, 2] Shi F. F. broadly classified them into internal electrode......, external electrode, and electrodeless microwave or high frequency reactors. [3] Softplasma™ is an internal electrode plasma setup powered by low frequenc~ gower supply. It was developed in late 90s for surface treatment of silicone rubber. [ ]- 5] It is a low pressure, low electron density, 3D homogenous...... plasma. In this study, we are presenting the surface modification"pf polymers by plasma polymerization using Softplasma™. Softplasma™ can be used for two major types of polymerization: polymerization of vinyl monomers, where plasma acts as initiator; chemical vapour deposition, where plasma acts...

  20. Why is intracellular ice lethal? A microscopical study showing evidence of programmed cell death in cryo-exposed embryonic axes of recalcitrant seeds of Acer saccharinum

    CSIR Research Space (South Africa)

    Wesley-Smith, J

    2015-10-01

    Full Text Available of Botany, Volume 115, Issue 6 pp. 991-1000. Why is intracellular ice lethal? A microscopical study showing evidence of programmed cell death in cryo- exposed embryonic axes of recalcitrant seeds of Acer saccharinum James Wesley-Smith1,2, Christina...

  1. Intracellular ice and cell survival in cryo-exposed embryonic axes of recalcitrant seeds of Acer saccharinum: an ultrastructural study of factors affecting cell and ice structures

    CSIR Research Space (South Africa)

    Wesley-Smith, J

    2014-03-01

    Full Text Available Annals of Botany 113: 695–709, 2014 doi:10.1093/aob/mct284, available online at www.aob.oxfordjournals.org Intracellular ice and cell survival in cryo-exposed embryonic axes of recalcitrant seeds of Acer saccharinum: an ultrastructural study...

  2. Evaluation of a single application of Neonicotnoid and multi-application contact insecticides for flatheaded borer management in field grown Acer rubrum L. cultivars

    Science.gov (United States)

    Two trials evaluated insecticides for flatheaded borer (Chrysobothris femorata [Olivier]) control and red maple (Acer rubrum L.) cultivar growth over a 4-year period. Soil-applied systemic insecticides (acephate, imidacloprid, clothianidin, dinotefuran, and thiamethoxam) and trunk-applied contact i...

  3. Influence of overstory density on ecophysiology of red oak (Quercus rubra) and sugar maple (Acer saccharum) seedlings in central Ontario shelterwoods

    Science.gov (United States)

    William C. Parker; Daniel C. Dey

    2008-01-01

    A field experiment was established in a secondgrowth hardwood forest dominated by red oak (Quercus rubra L.) to examine the effects of shelterwood overstory density on leaf gas exchange and seedling water status of planted red oak, naturally regenerated red oak and sugar maple (Acer saccharum Marsh.) seedlings during the first...

  4. Klíčení semen javoru jasanolistého (Acer negundo) a postup jeho invaze v ČR

    Czech Academy of Sciences Publication Activity Database

    Hrázský, Z.; Mihulka, Stanislav

    2008-01-01

    Roč. 43, Mater. 23 (2008), s. 151-162 ISSN 1212-3323. [Rostlinné invaze v ČR: situace, výzkum a management . Praha, 30.11.2007-01.12.2007] Institutional research plan: CEZ:AV0Z60050516 Keywords : Acer negundo * invasion * mapping of distributiion Subject RIV: EF - Botanics

  5. Photosynthetic acclimation of overstory Populus tremuloides and understory Acer saccharum to elevated atmospheric CO2 concentration: interactions with shade and soil nitrogen

    Science.gov (United States)

    Mark E. Kubiske; Donald R. Zak; Kurt S. Pregitzer; Yu Takeuchi

    2002-01-01

    We exposed Populus tremuloides Michx. and Acer saccharum Marsh. to a factorial combination of ambient and elevated atmospheric CO2 concentrations ([CO2]) and high-nitrogen (N) and low-N soil treatments in open-top chambers for 3 years. Our objective was to compare photosynthetic...

  6. Managing for delicious ecosystem service under climate change: can United States sugar maple (Acer saccharum) syrup production be maintained in a warming climate?

    Science.gov (United States)

    Stephen N. Matthews; Louis R. Iverson

    2017-01-01

    Sugar maple (Acer saccharum) is a highly valued tree in United States (US) and Canada, and its sap when collected from taps and concentrated, makes a delicious syrup. Understanding how this resource may be impacted by climate change and other threats is essential to continue management for maple syrup into the future. Here, we evaluate the current...

  7. Long-term calcium addition increases growth release, wound closure, and health of sugar maple (Acer saccharum) trees at the Hubbard Brook Experimental Forest

    Science.gov (United States)

    Brett A. Huggett; Paul G. Schaberg; Gary J. Hawley; Christopher Eager

    2007-01-01

    We surveyed and wounded forest-grown sugar maple (Acer saccharum Marsh.) trees in a long-term, replicated Ca manipulation study at the Hubbard Brook Experimental Forest in New Hampshire, USA. Plots received applications of Ca (to boost Ca availability above depleted ambient levels) or A1 (to compete with Ca uptake and further reduce Ca availability...

  8. The role of habitat factors in successful invasion of alien plant Acer negundo in riparian zones.

    Science.gov (United States)

    Sikorski, Piotr; Sikorska, Daria

    2016-04-01

    Ash-leaved maple (Acer negundo) is one of the most invasive species occurring in riparian zones. The invasion is especially effective in disturbed areas, as the plant favours anthropogenic sites. The plant was also observed to be able to penetrate into sandy bars, also those separated from the land, inaccessible to people. It's removal is time-consuming and laborious, often involves damage done to sensitive vegetation and the results are doubtful, as the plant quickly regenerates. The invasion patterns and establishment of ash-leaved maple in natural ecosystems are poorly investigated. The aim of this study was to test how habitat factors such as: light availability, soil characteristics and competition contribute to ash-leaved maple effective colonization of natural sand bars free from anthropogenic pressure. In 2014 sand bars located in Vistula River Valley in Warsaw were inventoried and classified basing on their development stage as 1 - initial, 2 - unstable, 3 - stable. Apart from the occurrence of the invasive ash-leaved maple the plants competing with it were recognized and the percentage of the shoots of shrubs and herbaceous plants was estimated. PAR was measured at ground level and 1 meter above ground, the thickness of organic layer formed on the top of the sand was also measured as the indicator of sand bar development stage. The maple's survival in extremely difficult conditions resembles the strategy of willows and poplars naturally occurring in the riparian zones, which are well adapted to this environment. The success of invasion strongly depends on the plants establishment during sand bars initial stage of development. The seedlings growth correlates with the age of the sand bar (r1=0,41, r2=0,42 i r3=0,57). The colonization lasts for 4-6 years and the individuals start to cluster in bigger parches. After that period the maple turns into the phase of competition for space. Habitat factors such as shading (r2=0,41 i r3=0,51) and organic layer

  9. Inflation of a Polymeric Menbrane

    DEFF Research Database (Denmark)

    Kristensen, Susanne B.; Larsen, Johannes R.; Hassager, Ole

    1998-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane.......We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane....

  10. Polymeric coordination compounds

    Indian Academy of Sciences (India)

    Administrator

    Metal coordination polymers with one- and two-dimensional structures are of current interest due to their possible relevance to material science 1. In continuation of our previous studies 2,3, several new polymeric compounds are reported here. Among the complexes of silver with aminomethyl pyridine (amp) ...

  11. Polymerized and functionalized triglycerides

    Science.gov (United States)

    Plant oils are useful sustainable raw materials for the development of new chemical products. As part of our research emphasis in sustainability and green polymer chemistry, we have explored a new method for polymerizing epoxidized triglycerides with the use of fluorosulfonic acid. Depending on the ...

  12. UV-B-mediated changes on below-ground communities associated with the roots of Acer saccharum

    International Nuclear Information System (INIS)

    Klironomos, J.N.; Allen, M.F.

    1995-01-01

    1. Little is known about how exposure to UV-B radiation affects rhizosphere microbes. Rhizosphere organisms are fed primarily by root-derived substrates and fulfil functions such as mineralization, immobilization, decomposition, pathogeneity and improvement of plant nutrition; they form the base of the below-ground food web. 2. In this study, we exposed Sugar Maple (Acer saccharum) seedlings to UV-B radiation in order to determine if UV-B influences the activities of mycorrhizal and non-mycorrhizal fungi, bacteria and microbe-feeding arthropods in the rhizosphere. 3. Below-ground organisms are greatly affected by UV-B radiation. Overall, carbon-flow in the plant soil system was shifted from a mutualistic-closed, mycorrhizal-dominated system to an opportunist-open, saprobe/pathogen-dominated one. (author)

  13. Winter climate change and fine root biogenic silica in sugar maple trees (Acer saccharum): Implications for silica in the Anthropocene

    Science.gov (United States)

    Maguire, Timothy J.; Templer, Pamela H.; Battles, John J.; Fulweiler, Robinson W.

    2017-03-01

    Winter temperatures are projected to increase over the next century, leading to reductions in winter snowpack and increased frequency of soil freezing in many northern forest ecosystems. Here we examine biogenic silica (BSi) concentrations in sugar maple (Acer saccharum) fine roots collected from a snow manipulation experiment at Hubbard Brook Experimental Forest (New Hampshire, USA). Increased soil freezing significantly lowered the BSi content of sugar maple fine roots potentially decreasing their capacity to take up water and dissolved nutrients. The reduced silica uptake (8 ± 1 kmol silica km-2) by sugar maple fine roots is comparable to silica export from temperate forest watersheds. We estimate that fine roots account for 29% of sugar maple BSi, despite accounting for only 4% of their biomass. These results suggest that increased frequency of soil freezing will reduce silica uptake by temperate tree roots, thereby changing silica availability in downstream receiving waters.

  14. Biosynthesis of gallic and ellagic acids with 14C-labeled compounds in Acer and Rhus leaves

    International Nuclear Information System (INIS)

    Ishikura, Nariyuki; Hayashida, Shunzo; Tazaki, Kiyoshi

    1984-01-01

    The biosynthetic pathway for gallic and ellagic acids in young, mature and autumn leaves of Acer buergerianum and Rhus succedanea was examined by tracer experiments, and also by isotope competition, with D-shikimic acid- 14 C, L-phenylalanine-U- 14 C, L-phenyllactic acid-U- 14 C, gallic acid-G- 14 C and their unlabeled compounds. In young leaves of both plants, the incorporation rate of labeled shikimic acid into gallic acid was significantly higher than that of labeled phenylalanine, whereas in the mature and autumn leaves the latter was a good precursor rather than the former for the gallic acid biosynthesis. Therefore, two pathways for gallic acid formation, through β-oxidation of phenylpropanoid and through dehydrogenation of shikimic acid, could be operating in Acer and Rhus leaves, and the preferential pathway is altered by leaf age. In both plants, the incorporation rate of labeled phenyllactic acid during a 24 hr metabolic period was almost the same as that of labeled phenylalanine. The incorporation of D-shikimic acid-G- 14 C, L-phenylalanine-U- 14 C and L-phenyllactic acid-U- 14 C into ellagic acid was very similar to the case of the radioactive gallic acid formation. Furthermore, regardless of the presence of unlabeled shikimic acid and/or phenylalanine, incorporation of the radioactivity of labeled gallic acid into ellagic acid occurred at a very high rate, suggesting the reciprocal radical reaction of gallic acid for the ellagic acid formation. The incorporation of labeled compounds into ellagitannins was also examined and their biosynthesis discussed further. (author)

  15. Radiation-induced heterophase polymerizations

    International Nuclear Information System (INIS)

    Carenza, M.; Palma, G.

    1985-01-01

    Investigations were carried out on the morphology of particles produced in the early stages of radiation-induced heterophase polymerization of acrylonitrile in quiescent conditions over a wide temperature range both in bulk and with addition of a solvent or a comonomer. The data were compared with the corresponding data obtained in the polymerization of vinyl chloride, producing an amorphous polymer, taking into account also the kinetic behaviours of the two polymerization systems. The particle morphologies in the two systems were quite similar at low polymerization temperatures but there were considerable differences when higher temperatures were involved. This change was interpreted on the basis of differences in compatability between the liquid phase and the polymer particle phase for the two systems. In order to account for the two different kinetic behaviours, a two-phase polymerization model was formulated and also a polymerization model in which the surface of the polymer particles was the locus of polymerization. (author)

  16. Thermally bisignate supramolecular polymerization

    Science.gov (United States)

    Venkata Rao, Kotagiri; Miyajima, Daigo; Nihonyanagi, Atsuko; Aida, Takuzo

    2017-11-01

    One of the enticing characteristics of supramolecular polymers is their thermodynamic reversibility, which is attractive, in particular, for stimuli-responsive applications. These polymers usually disassemble upon heating, but here we report a supramolecular polymerization that occurs upon heating as well as cooling. This behaviour arises from the use of a metalloporphyrin-based tailored monomer bearing eight amide-containing side chains, which assembles into a highly thermostable one-dimensional polymer through π-stacking and multivalent hydrogen-bonding interactions, and a scavenger, 1-hexanol, in a dodecane-based solvent. At around 50 °C, the scavenger locks the monomer into a non-polymerizable form through competing hydrogen bonding. On cooling, the scavenger preferentially self-aggregates, unlocking the monomer for polymerization. Heating also results in unlocking the monomer for polymerization, by disrupting the dipole and hydrogen-bonding interactions with the scavenger. Analogous to 'upper and lower critical solution temperature phenomena' for covalently bonded polymers, such a thermally bisignate feature may lead to supramolecular polymers with tailored complex thermoresponsive properties.

  17. Radiation chemistry of polymeric system

    International Nuclear Information System (INIS)

    Machi, Sueo; Ishigaki, Isao

    1978-01-01

    Among wide application of radiation in the field of polymer chemistry, practices of polymerization, graft polymerization, bridging, etc. are introduced hereinafter. As for the radiation sources of radiation polymerization, in addition to the 60 Co-γ ray with long permeation distance which has been usually applied, electron beam accelerators with high energy, large current and high reliability have come to be produced, and the liquid phase polymerization by electron beam has attracted attention industrially. Concerning polymerizing reactions, explanations were given to electron beam polymerization under high dose rate, the polymerization in supercooling state or under high pressure, and emulsifying polymerization. As for radiation bridging, radiation is applied for the bridging of hydrogel, acceleration of bridging and improvement of radiation resistance. It is also utilized for reforming membranes by graft polymerization, and synthesis of polymers for medical use. Application of fixed enzymes in the medical field has been investigated by fixing various enzymes by low temperature γ-ray polymerization with glassy monomers such as HEMA. (Kobatake, H.)

  18. Post-Polymerization Modifications of Polymeric Monolithic Columns: A Review

    Directory of Open Access Journals (Sweden)

    Sinéad Currivan

    2014-02-01

    Full Text Available The vast cache of methods used in polymeric monolithic column modification is presented herein, with specific attention to post-polymerization modification reactions. The modification of polymeric monolithic columns is defined and can include the modification of pre-existing surface groups, the addition of polymeric chains or indeed the addition of structures such as nano-particles and nano-structures. The use of these modifications can result in the specific patterning of monoliths, useful in microfluidic device design or in the investigation of modification optimization.

  19. ECOLOGICAL STRUCTURE OF ORIBATID MITE COMMUNITIES IN ACER PLATANOIDES L. STAND ON THE REMEDIATED SITE OF PAVLOGRADSKAYA MINE (PAVLOGRAD, THE DNIPROPETROVSK REGION

    Directory of Open Access Journals (Sweden)

    Y. L. Kulbachko

    2014-04-01

    Full Text Available Species composition and features of ecological structure of oribatid mite communities were studied on various options of bulk artificial-mixed soil in Acer platanoides L. stand growing on the remediated site of Pavlogradskaya mine (Pavlograd, Dnipropetrovsk Region. The ecological structure of oribatid population generally was damaged and this is typical for the man-modified ecosystems. Oribatid mite density in maple litter was higher than in the top layer of bulk soil (loess loam and chernozem by 4.1–7.4 times. Species abundance of oribatid mite was almost equal in maple litter and bulk soil. Punctoribates liber Pavlitshenko, 1991 prevailed generally as eudominant species in oribatid mite structure in Acer platanoides stand. The representatives of unspecialized life-forms were dominated among the oribatid life-forms in the remediated site with chernozem bulk. Key words: oribatid mites, forest remediation, mine dumps.

  20. Packaging based on polymeric materials

    Directory of Open Access Journals (Sweden)

    Jovanović Slobodan M.

    2005-01-01

    Full Text Available In the past two years the consumption of common in the developed countries world wide (high tonnage polymers for packaging has approached a value of 50 wt.%. In the same period more than 50% of the packaging units on the world market were made of polymeric materials despite the fact that polymeric materials present 17 wt.% of all packaging materials. The basic properties of polymeric materials and their environmental and economical advantages, providing them such a position among packaging materials, are presented in this article. Recycling methods, as well as the development trends of polymeric packaging materials are also presented.

  1. Synthesis of magnetic polymeric microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Gervald, A Yu; Gritskova, Inessa A; Prokopov, Nikolai I [M.V. Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow (Russian Federation)

    2010-05-13

    The key types of magnetic polymeric microspheres are considered. Methods of synthesis of different types of magnetic nanoparticles and of preparation of stable magnetic fluids on their basis are outlined. The overview of the methods for the manufacture of magnetic polymeric microspheres is presented. The effect of the synthesis conditions on the characteristics of magnetic polymeric microspheres such as the diameter and the particle size distribution and the content of magnetic material is discussed by particular examples. The application fields of magnetic polymeric microspheres are briefly surveyed.

  2. Synthesis of magnetic polymeric microspheres

    International Nuclear Information System (INIS)

    Gervald, A Yu; Gritskova, Inessa A; Prokopov, Nikolai I

    2010-01-01

    The key types of magnetic polymeric microspheres are considered. Methods of synthesis of different types of magnetic nanoparticles and of preparation of stable magnetic fluids on their basis are outlined. The overview of the methods for the manufacture of magnetic polymeric microspheres is presented. The effect of the synthesis conditions on the characteristics of magnetic polymeric microspheres such as the diameter and the particle size distribution and the content of magnetic material is discussed by particular examples. The application fields of magnetic polymeric microspheres are briefly surveyed.

  3. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

    In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  4. Living olefin polymerization processes

    Science.gov (United States)

    Schrock, Richard R.; Baumann, Robert

    2003-08-26

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  5. Living olefin polymerization processes

    Science.gov (United States)

    Schrock, Richard R.; Bauman, Robert

    2006-11-14

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  6. Developments of Chiral Metallocenes as Polymerization Catalysts

    Directory of Open Access Journals (Sweden)

    Takeshi Shiono

    2005-07-01

    Full Text Available This review article describes developments in chiral metallocenes as polymerization catalysts focusing on C2 symmetric ansa-zirconocene complexes. Selective synthesis of rac-isomers of ansa-zirconocenes are surveyed. Isospecific polymerizations of propylene catalyzed by chiral zirconocenes are summarized. Advanced series of polymerizations by chiral metallocenes such as asymmetric polymerization and polymerization of polar monomers are also introduced.

  7. Characterization of Endophytic Fungi from Acer ginnala Maxim. in an Artificial Plantation: Media Effect and Tissue-Dependent Variation

    Science.gov (United States)

    Zhan, Yaguang

    2012-01-01

    The community of endophytic fungi associated with Acer ginnala, a common tree in northeastern China, was investigated. Four media, PDA, Czapek’s, WA and Sabouraud’s, were used to inoculate explants from seeds, annual twigs and perennial twigs (xylem and bark). Media strongly affected the isolated species number, but not colonization frequency (CF) or isolation frequency (IF). To investigate media effect further, a Principal Component Analysis (PCA) was done. As a result, two components accounted for 86.502% of the total variance were extracted. These two components were named as PDA-determined factor (accounted for 45.139% of the total variance) and Czapek’s-determined factor (accounted for 41.363% of the total variance), respectively. This result suggested that only two media, PDA and Czapek’s, could be used instead of all four media in this study without affecting the isolation results significantly. In total, ten taxa were isolated in this study. Alternaria sp., Phomopsis sp., Neurospora sp. and Phoma sp. were dominant endophytes while Pleosporales Incertae Sedis sp., Cladosporium sp., Trichoderma sp. and Epicoccum sp. were rare taxa. Different tissues/organs had different endophyte assemblages. All tissue/organ pairs had low Bray-Curtis indices (endophyte dominance and diversity indices. Seeds had distinct assemblage, lower similarity and similar low diversity indices to annual twigs. These results suggested that tissue type determines the endophyte assemblage while age determines the diversity. PMID:23056451

  8. Physiological and foliar injury responses of Prunus serotina, Fraxinus americana, and Acer rubrum seedlings to varying soil moisture and ozone

    International Nuclear Information System (INIS)

    Schaub, M.; Skelly, J.M.; Steiner, K.C.; Davis, D.D.; Pennypacker, S.P.; Zhang, J.; Ferdinand, J.A.; Savage, J.E.; Stevenson, R.E.

    2003-01-01

    High soil water availability favors ozone uptake, increases foliar injury, and exacerbates the negative ozone effect on gas exchange of seedlings of deciduous tree species. - Sixteen black cherry (Prunus serotina, Ehrh.), 10 white ash (Fraxinus americana, L.) and 10 red maple (Acer rubrum, L.) 1-year old seedlings were planted per plot in 1997 on a former nursery bed within 12 open-top chambers and six open plots. Seedlings were exposed to three different ozone scenarios (ambient air: 100% O 3 ; non-filtered air: 98% ambient O 3 ; charcoal-filtered air: 50% ambient O 3 ) within each of two different water regimes (nine plots irrigated, nine plots non-irrigated) during three growing seasons. During the 1998 and 1999 growing season, leaf gas exchange, plant water relations, and foliar injury were measured. Climatic data, ambient- and chamber-ozone-concentrations were monitored. We found that seedlings grown under irrigated conditions had similar (in 1998) but significantly higher gas exchange rates (in 1999) than seedlings grown within non-irrigated plots among similar ozone exposures. Cherry and ash had similar ozone uptake but cherry developed more ozone-induced injury (<34% affected leaf area, LAA) than ash (<5% LAA), while maple rarely showed foliar injury, indicating the species differed in ozone sensitivity. Significantly more severe injury on seedlings grown under irrigated conditions than seedlings grown under non-irrigated conditions demonstrated that soil moisture altered seedling responses to ambient ozone exposures

  9. Polymerization with freezing

    International Nuclear Information System (INIS)

    Ben-Naim, E; Krapivsky, P L

    2005-01-01

    Irreversible aggregation processes involving reactive and frozen clusters are investigated using the rate equation approach. In aggregation events, two clusters join irreversibly to form a larger cluster; additionally, reactive clusters may spontaneously freeze. Frozen clusters do not participate in merger events. Generally, freezing controls the nature of the aggregation process, as demonstrated by the final distribution of frozen clusters. The cluster mass distribution has a power-law tail, F k ∼k -γ , when the freezing process is sufficiently slow. Different exponents, γ = 1 and 3, are found for the constant and the product aggregation rates, respectively. For the latter case, the standard polymerization model, either no gels, or a single gel, or even multiple gels, may be produced

  10. Collaborative Research: Polymeric Multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Shenqiang [Temple Univ., Philadelphia, PA (United States). College of Engineering

    2017-04-20

    The goal of this project is to investigate room temperature magnetism and magnetoelectric coupling of polymeric multiferroics. A new family of molecular charge-transfer crystals has been emerged as a fascinating opportunity for the development of all-organic electrics and spintronics due to its weak hyperfine interaction and low spin-orbit coupling; nevertheless, direct observations of room temperature magnetic spin ordering have yet to be accomplished in organic charge-transfer solids. Furthermore, room temperature magnetoelectric coupling effect hitherto known multiferroics, is anticipated in organic donor-acceptor complexes because of magnetic field effects on charge-transfer dipoles, yet this is also unexplored. The PI seeks to fundamental understanding of the control of organic crystals to demonstrate and explore room temperature multiferroicity. The experimental results have been verified through the theoretical modeling.

  11. Polymeric micelles for drug targeting.

    Science.gov (United States)

    Mahmud, Abdullah; Xiong, Xiao-Bing; Aliabadi, Hamidreza Montazeri; Lavasanifar, Afsaneh

    2007-11-01

    Polymeric micelles are nano-delivery systems formed through self-assembly of amphiphilic block copolymers in an aqueous environment. The nanoscopic dimension, stealth properties induced by the hydrophilic polymeric brush on the micellar surface, capacity for stabilized encapsulation of hydrophobic drugs offered by the hydrophobic and rigid micellar core, and finally a possibility for the chemical manipulation of the core/shell structure have made polymeric micelles one of the most promising carriers for drug targeting. To date, three generations of polymeric micellar delivery systems, i.e. polymeric micelles for passive, active and multifunctional drug targeting, have arisen from research efforts, with each subsequent generation displaying greater specificity for the diseased tissue and/or targeting efficiency. The present manuscript aims to review the research efforts made for the development of each generation and provide an assessment on the overall success of polymeric micellar delivery system in drug targeting. The emphasis is placed on the design and development of ligand modified, stimuli responsive and multifunctional polymeric micelles for drug targeting.

  12. High temperature structural, polymeric foams from high internal emulsion polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Hoisington, M.A.; Duke, J.R.; Apen, P.G.

    1996-02-01

    In 1982, a high internal phase emulsion (HIPE) polymerization process to manufacture microcellular, polymeric foam systems was patented by Unilever. This patent discloses a polymerization process that occurs in a water-in-oil emulsion in which the water represents at least 76% of the emulsion by volume. The oil phase consists of vinyl monomers such as styrene and acrylates that are crosslinked by divinyl monomers during polymerization. After polymerization and drying to remove the water phase, the result is a crosslinked polymer foam with an open cell microstructure that is homogeneous throughout in terms of morphology, density, and mechanical properties. Since 1982, numerous patents have examined various HIPE polymerized foam processing techniques and applications that include absorbents for body fluids, cleaning materials, and ion exchange systems. All the published HIPE polymerized foams have concentrated on materials for low temperature applications. Copolymerization of styrene with maleic anhydride and N-substituted maleimides to produce heat resistant thermoplastics has been studied extensively. These investigations have shown that styrene will free radically copolymerize with N-substituted maleimides to create an alternating thermoplastic copolymer with a Tg of approximately 200{degrees}C. However, there are many difficulties in attempting the maleimide styrene copolymerization in a HIPE such as lower polymerization temperatures, maleimide solubility difficulties in both styrene and water, and difficulty obtaining a stable HIPE with a styrene/maleimide oil phase. This work describes the preparation of copolymer foams from N-ethylmaleimide and Bis(3-ethyl-5-methyl-4-maleimide-phenyl)methane with styrene based monomers and crosslinking agents.

  13. Organometallic Polymeric Conductors

    Science.gov (United States)

    Youngs, Wiley J.

    1997-01-01

    For aerospace applications, the use of polymers can result in tremendous weight savings over metals. Suitable polymeric materials for some applications like EMI shielding, spacecraft grounding, and charge dissipation must combine high electrical conductivity with long-term environmental stability, good processability, and good mechanical properties. Recently, other investigators have reported hybrid films made from an electrically conductive polymer combined with insulating polymers. In all of these instances, the films were prepared by infiltrating an insulating polymer with a precursor for a conductive polymer (either polypyrrole or polythiophene), and oxidatively polymerizing the precursor in situ. The resulting composite films have good electrical conductivity, while overcoming the brittleness inherent in most conductive polymers. Many aerospace applications require a combination of properties. Thus, hybrid films made from polyimides or other engineering resins are of primary interest, but only if conductivities on the same order as those obtained with a polystyrene base could be obtained. Hence, a series of experiments was performed to optimize the conductivity of polyimide-based composite films. The polyimide base chosen for this study was Kapton. 3-MethylThiophene (3MT) was used for the conductive phase. Three processing variables were identified for producing these composite films, namely time, temperature, and oxidant concentration for the in situ oxidation. Statistically designed experiments were used to examine the effects of these variables and synergistic/interactive effects among variables on the electrical conductivity and mechanical strength of the films. Multiple linear regression analysis of the tensile data revealed that temperature and time have the greatest effect on maximum stress. The response surface of maximum stress vs. temperature and time (for oxidant concentration at 1.2 M) is shown. Conductivity of the composite films was measured for

  14. Genetic structure and hierarchical population divergence history of Acer mono var. mono in South and Northeast China.

    Directory of Open Access Journals (Sweden)

    Chunping Liu

    Full Text Available Knowledge of the genetic structure and evolutionary history of tree species across their ranges is essential for the development of effective conservation and forest management strategies. Acer mono var. mono, an economically and ecologically important maple species, is extensively distributed in Northeast China (NE, whereas it has a scattered and patchy distribution in South China (SC. In this study, the genetic structure and demographic history of 56 natural populations of A. mono var. mono were evaluated using seven nuclear microsatellite markers. Neighbor-joining tree and STRUCTURE analysis clearly separated populations into NE and SC groups with two admixed-like populations. Allelic richness significantly decreased with increasing latitude within the NE group while both allelic richness and expected heterozygosity showed significant positive correlation with latitude within the SC group. Especially in the NE region, previous studies in Quercus mongolica and Fraxinus mandshurica have also detected reductions in genetic diversity with increases in latitude, suggesting this pattern may be common for tree species in this region, probably due to expansion from single refugium following the last glacial maximum (LGM. Approximate Bayesian Computation-based analysis revealed two major features of hierarchical population divergence in the species' evolutionary history. Recent divergence between the NE group and the admixed-like group corresponded to the LGM period and ancient divergence of SC groups took place during mid-late Pleistocene period. The level of genetic differentiation was moderate (FST  = 0.073; G'ST  = 0.278 among all populations, but significantly higher in the SC group than the NE group, mirroring the species' more scattered distribution in SC. Conservation measures for this species are proposed, taking into account the genetic structure and past demographic history identified in this study.

  15. Characterization of endophytic fungi from Acer ginnala Maxim. in an artificial plantation: media effect and tissue-dependent variation.

    Directory of Open Access Journals (Sweden)

    Fenghui Qi

    Full Text Available The community of endophytic fungi associated with Acer ginnala, a common tree in northeastern China, was investigated. Four media, PDA, Czapek's, WA and Sabouraud's, were used to inoculate explants from seeds, annual twigs and perennial twigs (xylem and bark. Media strongly affected the isolated species number, but not colonization frequency (CF or isolation frequency (IF. To investigate media effect further, a Principal Component Analysis (PCA was done. As a result, two components accounted for 86.502% of the total variance were extracted. These two components were named as PDA-determined factor (accounted for 45.139% of the total variance and Czapek's-determined factor (accounted for 41.363% of the total variance, respectively. This result suggested that only two media, PDA and Czapek's, could be used instead of all four media in this study without affecting the isolation results significantly. In total, ten taxa were isolated in this study. Alternaria sp., Phomopsis sp., Neurospora sp. and Phoma sp. were dominant endophytes while Pleosporales Incertae Sedis sp., Cladosporium sp., Trichoderma sp. and Epicoccum sp. were rare taxa. Different tissues/organs had different endophyte assemblages. All tissue/organ pairs had low Bray-Curtis indices (<0.3 except for bark and annual twigs (0.63. Compared to perennial twigs, annual twigs had a lower taxon number, lower isolate number, lower endophyte dominance and diversity indices. Seeds had distinct assemblage, lower similarity and similar low diversity indices to annual twigs. These results suggested that tissue type determines the endophyte assemblage while age determines the diversity.

  16. Genetic structure and hierarchical population divergence history of Acer mono var. mono in South and Northeast China.

    Science.gov (United States)

    Liu, Chunping; Tsuda, Yoshiaki; Shen, Hailong; Hu, Lijiang; Saito, Yoko; Ide, Yuji

    2014-01-01

    Knowledge of the genetic structure and evolutionary history of tree species across their ranges is essential for the development of effective conservation and forest management strategies. Acer mono var. mono, an economically and ecologically important maple species, is extensively distributed in Northeast China (NE), whereas it has a scattered and patchy distribution in South China (SC). In this study, the genetic structure and demographic history of 56 natural populations of A. mono var. mono were evaluated using seven nuclear microsatellite markers. Neighbor-joining tree and STRUCTURE analysis clearly separated populations into NE and SC groups with two admixed-like populations. Allelic richness significantly decreased with increasing latitude within the NE group while both allelic richness and expected heterozygosity showed significant positive correlation with latitude within the SC group. Especially in the NE region, previous studies in Quercus mongolica and Fraxinus mandshurica have also detected reductions in genetic diversity with increases in latitude, suggesting this pattern may be common for tree species in this region, probably due to expansion from single refugium following the last glacial maximum (LGM). Approximate Bayesian Computation-based analysis revealed two major features of hierarchical population divergence in the species' evolutionary history. Recent divergence between the NE group and the admixed-like group corresponded to the LGM period and ancient divergence of SC groups took place during mid-late Pleistocene period. The level of genetic differentiation was moderate (FST  = 0.073; G'ST  = 0.278) among all populations, but significantly higher in the SC group than the NE group, mirroring the species' more scattered distribution in SC. Conservation measures for this species are proposed, taking into account the genetic structure and past demographic history identified in this study.

  17. Kinetics of silica polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Weres, O.; Yee, A.; Tsao, L.

    1980-05-01

    The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.

  18. Electroactivity in Polymeric Materials

    CERN Document Server

    2012-01-01

    Electroactivity in Polymeric Materials provides an in-depth view of the theory of electroactivity and explores exactly how and why various electroactive phenomena occur. The book explains the theory behind electroactive bending (including ion-polymer-metal-composites –IPMCs), dielectric elastomers, electroactive contraction, and electroactive contraction-expansion cycles.  The book also balances theory with applications – how electroactivity can be used – drawing inspiration from the manmade mechanical world and the natural world around us.  This book captures: A complete introduction to electroactive materials including examples and recent developments The theory and applications of numerous topics like electroactive bending of dielectric elastomers and electroactive contraction and expansion New topics, such as biomimetic applications and energy harvesting This is a must-read within the electroactive community, particularly for professionals and graduate students who are interested in the ...

  19. Polyolefin nanocomposites in situ polymerization

    International Nuclear Information System (INIS)

    Galland, Griselda Barrera; Fim, Fabiana de C.; Milani, Marceo A.; Silva, Silene P. da; Forest, Tadeu; Radaelli, Gislaine; Basso, Nara R.S.; Quijada, Raul

    2011-01-01

    Polyethylene and polypropylene nanocomposites using grapheme nanosheets and treated chrysotile have been synthesized by in situ polymerization using metallocene catalysts. The fillers have been submitted to acid, thermal and/ou ultrasound treatments before to introduce them into the polymerization reactor. A complete characterization of the fillers has been done. The nanocomposites have been characterized by SEM, TEM, DRX and AFM. The thermal, mechanic -dynamic, mechanical and electrical properties of the nanocomposites are discussed. (author)

  20. Der Eschen-Ahorn (Acer negundo) am nördlichen Oberrhein : Beitrag zur naturschutzfachlichen Einschätzung eines Neophyten

    OpenAIRE

    Baumgärtel, Ralph

    2008-01-01

    Der Eschen-Ahorn (Acer negundo) hat in Mitteleuropa seinen Verbreitungsschwerpunkt an der Donau unterstrom von Wien sowie am Nördlichen Oberrhein, am Mittel- und Niederrhein. A. negundo zeichnet sich durch eine hohe Überflutungstoleranz aus, seine Samen weisen gegenüber den Diasporen von Weiden und Pappeln eine wesentlich längere Keimfähigkeit auf. Dadurch ist die Art in der Lage, offene Standorte in dynamischen Systemen über einen langen Zeitraum zu besiedeln und einheimische Gehölze zu verd...

  1. Effects of forest fragmentation on the mating system of a cool-temperate heterodichogamous tree Acer mono

    Directory of Open Access Journals (Sweden)

    Satoshi Kikuchi

    2015-01-01

    Full Text Available Pollination is a key process for reproduction and gene flow in flowering plants. Anthropogenic habitat fragmentation, however, can disrupt plant–pollinator interactions, and may have a negative impact on the reproductive success and population viability of entomophilous plants. Heterodichogamous plants containing protandrous and protogynous individuals within a population may be susceptible to habitat fragmentation due to a lack of available mating partners. In this study, we investigated the effects of forest fragmentation on the mating system in the heterodichogamous plant Acer mono, a major constituent of cool-temperate deciduous forests in Japan. Microsatellite analysis was applied to 212 adult trees and 17 seed families from continuous and fragmented forests. Dispersal kernel modeling using the neighborhood model indicated that pollen dispersal of A. mono was highly fat-tailed. The estimated parameters of the model suggested that the siring success of a pollen donor increased approximately fivefold, with a 100 cm increase in its diameter at breast height (DBH, and that disassortative mating was five times more frequent than assortative mating. The mating system parameters of each mother tree, outcrossing rate (tm, biparental inbreeding (tm−ts, and paternity correlation (rpm varied among sites and conditions, depending on the local density of potential pollen donors. Whereas A. mono was effectively outcrossed (tm=0.901, tm−ts=0.052, and the number of effective sires was 1/rpm=14.93 in the continuous forest, clumped trees within the fragmented forest showed increased biparental inbreeding and reduced pollen pool genetic diversity (tm=0.959, tm−ts=0.245,1/rpm=1.742 as a result of localized mating combined with spatial genetic structures. In contrast, the isolated trees had a higher selfing rate, but the pollen pool diversity was maintained (tm=0.801, tm−ts=0.022, and 1/rpm=15.63 due to frequent long-distance pollination. These

  2. Climate Change in the School Yard: Monitoring the Health of Acer Saccharum with A Maple Report Card

    Science.gov (United States)

    Carlson, M.; Diller, A.; Rock, B. N.

    2012-12-01

    K-12 Teachers and students engage in authentic science and a research partnership with scientists in Maple Watch, a University of New Hampshire outreach program. Maple Watch is a hands-on, inquiry-based program in which students learn about climate change and air quality as well as many other environmental stress factors which may affect the health of sugar maple. The iconic New England tree is slated to lose 52% of its range in this century. Maple Watch builds on the 20-year record of Forest Watch, a K-12 program in which students and teachers have contributed annual research specimens and data to a UNH study of tropospheric ozone and its impact on white pine (Pinus strobus). Maple Watch students monitor sugar maples (Acer saccharum) year-round for signals of strain and disease. Students report the first run in sap season, bud burst and leaf development, and leaf senescence and fall. Across New England the timing of these phenologic events is changing with climate warming. Students assess maple health with simple measures of leaf development in May, leaf senescence in early fall and bud quality in late fall. Simple student arithmetic rankings of leaf and bud health correlate with chlorophyll content and spectral reflectance measures that students can analyze and compare with researchers at UNH. Grading their trees for each test on a one-two-three scale, students develop a Maple Report Card for each type of measurement, which presents an annual portrait of tree health. Year-by-year, schools across the sugar maple's 31 million acre range could monitor changes in tree health. The change over time in maple health can be graphed in parallel with the Goddard Space Institute's Common Sense Climate Index. Four teachers, listed as co-authors here, began a pilot study with Maple Watch in 2010, contributing sap samples and sharing curricular activities with UNH. Pilot Maple Watch schools already manage stands of sugar maples and make maple syrup and are assisting in training

  3. Revealing the cellular metabolism and microstructural changes in vivo in senescing Acer saccharum leaves using two-photon FLIM and full-field OCM

    Science.gov (United States)

    Chakraborty, Sandeep; Anna, Tulsi; Kuo, Wen-Chuan; Chiou, Arthur

    2016-10-01

    Seasonal as well as climate changes have immense effect on bud burst, leaf color and leaf abscission. Autumn phenology of leaves is clearly distinguishable in deciduous plant leaves where the leaf color changes from green to red (leaf senescence). In this work, two-photon fluorescence lifetime imaging microscopy (2P-FLIM) and full-field optical coherence microscopy (FF-OCM) were applied to study mitochondrial activity and microstructural changes, respectively, in the senescence of Acer saccharum (Sugar maple) leaves. Fluorescence lifetime of reduced nicotinamide adenine dinucleotide phosphate [NAD(P)H] was recorded using 2P-FLIM to quantify the cellular metabolic changes. Compared to the green leaves, the red leaves showed a 19% increase (P fluorescence lifetime of NAD(P)H, and a 52% decrease (p protein-bound NAD(P)H ratio. This infers a significant change in mitochondrial metabolic regulation in red leaves in contrast to green leaves. Additionally, en-face sectional images at 0.8 μm axial resolutions of the green and the red color Acer saccharum leaves via FF-OCM using white light emitting diode (WLED) showed a well-defined microstructure of epicuticular waxy layer in green leaves as compared to red leaves where disintegrated microstructure was observed. Our approach can potentially be used to correlate mitochondrial activity with epicuticular microstructural changes in senescing leaves and other biological tissues.

  4. The ACER pollen and charcoal database: a global resource to document vegetation and fire response to abrupt climate changes during the last glacial period

    Science.gov (United States)

    Sánchez Goñi, María Fernanda; Desprat, Stéphanie; Daniau, Anne-Laure; Bassinot, Frank C.; Polanco-Martínez, Josué M.; Harrison, Sandy P.; Allen, Judy R. M.; Anderson, R. Scott; Behling, Hermann; Bonnefille, Raymonde; Burjachs, Francesc; Carrión, José S.; Cheddadi, Rachid; Clark, James S.; Combourieu-Nebout, Nathalie; Mustaphi, Colin. J. Courtney; Debusk, Georg H.; Dupont, Lydie M.; Finch, Jemma M.; Fletcher, William J.; Giardini, Marco; González, Catalina; Gosling, William D.; Grigg, Laurie D.; Grimm, Eric C.; Hayashi, Ryoma; Helmens, Karin; Heusser, Linda E.; Hill, Trevor; Hope, Geoffrey; Huntley, Brian; Igarashi, Yaeko; Irino, Tomohisa; Jacobs, Bonnie; Jiménez-Moreno, Gonzalo; Kawai, Sayuri; Kershaw, A. Peter; Kumon, Fujio; Lawson, Ian T.; Ledru, Marie-Pierre; Lézine, Anne-Marie; Liew, Ping Mei; Magri, Donatella; Marchant, Robert; Margari, Vasiliki; Mayle, Francis E.; Merna McKenzie, G.; Moss, Patrick; Müller, Stefanie; Müller, Ulrich C.; Naughton, Filipa; Newnham, Rewi M.; Oba, Tadamichi; Pérez-Obiol, Ramón; Pini, Roberta; Ravazzi, Cesare; Roucoux, Katy H.; Rucina, Stephen M.; Scott, Louis; Takahara, Hikaru; Tzedakis, Polichronis C.; Urrego, Dunia H.; van Geel, Bas; Valencia, B. Guido; Vandergoes, Marcus J.; Vincens, Annie; Whitlock, Cathy L.; Willard, Debra A.; Yamamoto, Masanobu

    2017-09-01

    Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard-Oeschger (D-O) cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D-O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses) global database, which includes 93 pollen records from the last glacial period (73-15 ka) with a temporal resolution better than 1000 years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (14C, 234U/230Th, optically stimulated luminescence (OSL), 40Ar/39Ar-dated tephra layers) has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft AccessTM at https://doi.org/10.1594/PANGAEA.870867.

  5. On-demand photoinitiated polymerization

    Science.gov (United States)

    Boydston, Andrew J; Grubbs, Robert H; Daeffler, Chris; Momcilovic, Nebojsa

    2013-12-10

    Compositions and methods for adjustable lenses are provided. In some embodiments, the lenses contain a lens matrix material, a masking compound, and a prepolymer. The lens matrix material provides structure to the lens. The masking compound is capable of blocking polymerization or crosslinking of the prepolymer, until photoisomerization of the compound is triggered, and the compound is converted from a first isomer to a second isomer having a different absorption profile. The prepolymer is a composition that can undergo a polymerization or crosslinking reaction upon photoinitiation to alter one or more of the properties of the lenses.

  6. Pentafluorosulfanyl Substituents in Polymerization Catalysis.

    Science.gov (United States)

    Kenyon, Philip; Mecking, Stefan

    2017-10-04

    Highly electron-withdrawing pentafluorosulfanyl groups were probed as substituents in an organometallic catalyst. In Ni(II) salicylaldiminato complexes as an example case, these highly electron-withdrawing substituents allow for polymerization of ethylene to higher molecular weights with reduced branching due to significant reductions in β-hydrogen elimination. Combined with the excellent functional group tolerance of neutral Ni(II) complexes, this suppression of β-hydrogen elimination allows for the direct polymerization of ethylene in water to nanocrystal dispersions of disentangled, ultrahigh-molecular-weight linear polyethylene.

  7. synthesis of microporous polymers by frontal polymerization

    Indian Academy of Sciences (India)

    Unknown

    EGDM) copolymers of varying compositions were synthesized by free-radically triggered thermal frontal polymerization (FP) as well as by suspension polymerization (SP) using azobisisobutyronitrile [AIBN] as initiator. The two sets of copolymers.

  8. Functionalization and Polymerization on the CNT Surfaces

    KAUST Repository

    Albuerne, Julio

    2013-07-01

    In this review we focus on the current status of using carbon nanotube (CNT) as a filler for polymer nanocomposites. Starting with the historical background of CNT, its distinct properties and the surface functionalization of the nanotube, the three different surface polymerization techniques, namely grafting "from", "to" and "through/in between" were discussed. Wider focus has been given on "grafting from" surface initiated polymerizations, including atom transfer radical polymerization (ATRP), reversible addition fragmentation chain-transfer (RAFT) Polymerization, nitroxide mediated polymerization (NMP), ring opening polymerization (ROP) and other miscellaneous polymerization methods. The grafting "to" and "through / in between" also discussed and compared with grafting from polymerization. The merits and shortcomings of all three grafting methods were discussed and the bottleneck issue in grafting from method has been highlighted. Furthermore the current and potential future industrial applications were deliberated. Finally the toxicity issue of CNTs in the final product has been reviewed with the limited available literature knowledge. © 2013 Bentham Science Publishers.

  9. Fluoropolymer materials and architectures prepared by controlled radical polymerizations

    DEFF Research Database (Denmark)

    Hansen, Natanya Majbritt Louie; Jankova Atanasova, Katja; Hvilsted, Søren

    2007-01-01

    This review initially summarizes the mechanisms, merits and limitations of the three controlled radical polymerizations: nitroxide mediated polymerization (NMP), atom transfer radical polymerization (ATRP) or metal catalyzed living radical polymerization, and reversible addition–fragmentation chain...

  10. Capillary thinning of polymeric filaments

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Szabo, Peter; Hassager, Ole

    1998-01-01

    The capillary thinning of a polymeric filament is analysed experimentally as well as by means of numerical simulation. The experimental procedure is as follows. Initially a liquid sample is kept between two cylindrical plates. Then the bottom plate is lowered under gravity to yield a given strain...

  11. Actin Polymerization and ATP Hydrolysis

    Science.gov (United States)

    Korn, Edward D.; Carlier, Marie-France; Pantaloni, Dominique

    1987-10-01

    F-actin is the major component of muscle thin filaments and, more generally, of the microfilaments of the dynamic, multifunctional cytoskeletal systems of nonmuscle eukaryotic cells. Polymeric F-actin is formed by reversible noncovalent self-association of monomeric G-actin. To understand the dynamics of microfilament systems in cells, the dynamics of polymerization of pure actin must be understood. The following model has emerged from recent work. During the polymerization process, adenosine 5'-triphosphate (ATP) that is bound to G-actin is hydrolyzed to adenosine 5'-diphosphate (ADP) that is bound to F-actin. The hydrolysis reaction occurs on the F-actin subsequent to the polymerization reaction in two steps: cleavage of ATP followed by the slower release of inorganic phosphate (Pi). As a result, at high rates of filament growth a transient cap of ATP-actin subunits exists at the ends of elongating filaments, and at steady state a stabilizing cap of ADP \\cdot Pi-actin subunits exists at the barbed ends of filaments. Cleavage of ATP results in a highly stable filament with bound ADP \\cdot Pi, and release of Pi destabilizes the filament. Thus these two steps of the hydrolytic reaction provide potential mechanisms for regulating the monomer-polymer transition.

  12. Biodegradable polymeric prodrugs of naltrexone

    NARCIS (Netherlands)

    Bennet, D.B.; Li, X.; Adams, N.W.; Kim, S.W.; Hoes, C.J.T.; Hoes, C.J.T.; Feijen, Jan

    1991-01-01

    The development of a biodegradable polymeric drug delivery system for the narcotic antagonist naltrexone may improve patient compliance in the treatment of opiate addiction. Random copolymers consisting of the ¿-amino acids N5-(3-hydroxypropyl--glutamine and -leucine were synthesized with equimolar

  13. Preparations of spherical polymeric particles from Tanzanian ...

    African Journals Online (AJOL)

    Spherical Polymeric Particles (SPP) have been prepared from Tanzanian Cashew Nut Shell Liquid (CNSL) by suspension polymerization technique involving either step-growth or chain- growth polymerization mechanisms. The sizes of the SPP, which ranged from 0.1 to 2.0 mm were strongly influenced by the amounts of ...

  14. Glycine Polymerization on Oxide Minerals

    Science.gov (United States)

    Kitadai, Norio; Oonishi, Hiroyuki; Umemoto, Koichiro; Usui, Tomohiro; Fukushi, Keisuke; Nakashima, Satoru

    2017-06-01

    It has long been suggested that mineral surfaces played an important role in peptide bond formation on the primitive Earth. However, it remains unclear which mineral species was key to the prebiotic processes. This is because great discrepancies exist among the reported catalytic efficiencies of minerals for amino acid polymerizations, owing to mutually different experimental conditions. This study examined polymerization of glycine (Gly) on nine oxide minerals (amorphous silica, quartz, α-alumina and γ-alumina, anatase, rutile, hematite, magnetite, and forsterite) using identical preparation, heating, and analytical procedures. Results showed that a rutile surface is the most effective site for Gly polymerization in terms of both amounts and lengths of Gly polymers synthesized. The catalytic efficiency decreased as rutile > anatase > γ-alumina > forsterite > α- alumina > magnetite > hematite > quartz > amorphous silica. Based on reported molecular-level information for adsorption of Gly on these minerals, polymerization activation was inferred to have arisen from deprotonation of the NH3 + group of adsorbed Gly to the nucleophilic NH2 group, and from withdrawal of electron density from the carboxyl carbon to the surface metal ions. The orientation of adsorbed Gly on minerals is also a factor influencing the Gly reactivity. The examination of Gly-mineral interactions under identical experimental conditions has enabled the direct comparison of various minerals' catalytic efficiencies and has made discussion of polymerization mechanisms and their relative influences possible Further systematic investigations using the approach reported herein (which are expected to be fruitful) combined with future microscopic surface analyses will elucidate the role of minerals in the process of abiotic peptide bond formation.

  15. Ecotoxicological effects evoked in hydrophytes by leachates of invasive Acer negundo and autochthonous Alnus glutinosa fallen off leaves during their microbial decomposition

    International Nuclear Information System (INIS)

    Krevš, Alina; Darginavičienė, Jūratė; Gylytė, Brigita; Grigutytė, Reda; Jurkonienė, Sigita; Karitonas, Rolandas; Kučinskienė, Alė; Pakalnis, Romas; Sadauskas, Kazys; Vitkus, Rimantas

    2013-01-01

    Throughout 90-day biodegradation under microaerobic conditions, invasive to Lithuania species boxelder maple (Acer negundo) leaves lost 1.5-fold more biomass than that of autochthonous black alder (Alnus glutinosa), releasing higher contents of N tot , ammonium and generating higher BOD 7 . Boxelder maple leaf leachates were characterized by higher total bacterial numbers and colony numbers of heterotrophic and cellulose-decomposing bacteria than those of black alder. The higher toxicity of A. negundo aqueous extracts and leachates to charophyte cell (Nitellopsis obtusa), the inhabitant of clean lakes, were manifested at mortality and membrane depolarization levels, while the effect on H + -ATPase activity in membrane preparations from the same algae was stronger in case of A. glutinosa. Duckweed (Lemna minor), a bioindicator of eutrophic waters, was more sensitive to leaf leachates of A. glutinosa. Fallen leaves and leaf litter leachates from invasive and native species of trees, which enter water body, affect differently microbial biodestruction and aquatic vegetation in freshwater systems. - Highlights: ► We examined Acer negundo and Alnus glutinosa leaf extract effects on hydrophytes. ► Nitellopsis obtusa and Lemna minor responded differently to leaf litter leachates. ► 90-day biodegraded A. negundo leaves lost twofold more biomass than that of A. glutinosa. ► A. negundo leachates evoked higher mortality and cell depolarization of N. obtusa. ► Leachates affected H + -ATPase activity in algae membrane preparations. - Fallen leaves and leaf litter leachates from invasive and native species of trees, which enter waterbody can be environmental factor affecting differently microbial biodestruction and aquatic vegetation in freshwater systems, thus influencing ecological scenarios.

  16. The ACER pollen and charcoal database: a global resource to document vegetation and fire response to abrupt climate changes during the last glacial period

    Directory of Open Access Journals (Sweden)

    M. F. Sánchez Goñi

    2017-09-01

    Full Text Available Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard–Oeschger (D–O cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D–O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses global database, which includes 93 pollen records from the last glacial period (73–15 ka with a temporal resolution better than 1000 years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (14C, 234U∕230Th, optically stimulated luminescence (OSL, 40Ar∕39Ar-dated tephra layers has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft AccessTM at https://doi.org/10.1594/PANGAEA.870867.

  17. Polymerization catalyst, production and use

    International Nuclear Information System (INIS)

    Best, S.A.

    1987-01-01

    A process is described for polymerization of ethylene and alpha-olefins having from 1 to 20 carbon atoms or mixtures of ethylene, alpha-olefins and diolefins. The process comprises polymerizing one or more olefins in the presence of the catalyst system comprising (a) an organoaluminum cocatalyst, and (b) a vanadium containing a catalyst component obtained by treating an inert solid support material in an inert solvent with (i) an organoaluminum compound represented by the formula R/sub m/AIX/sub 3-m/, wherein R represents an alkyl group, cycloalkyl group or aryl group having from 1 to 18 carbon atoms, X represents halogen atoms, and 1≤m≤3, (ii) an acyl halide, and (iii) a vanadium compound. Another process is identified wherein the inert solid support material is an inorganic oxide or mixtures of inorganic oxides. Also a process wherein the inorganic oxide is silica is described

  18. Ring opening metathesis polymerization catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Grubbs, R.H.; Johnson, L.K.; Novak, B.M.; Hillmyer, M.; Benedicto, A.; France, M.; Nguyen, S.T. [California Institute of Technology, Pasadena, CA (United States)

    1993-12-31

    Over the past eight years, a number of new catalysts for the ring opening metathesis polymerization of cyclic olefins have been developed. These catalysts are simple organometallic complexes containing metal carbon multiple bonds that in most cases polymerize olefins by a living process. These catalysts have been used to prepare a family of near monodispersed and structurally homogeneous polymers, a series of telechelic polymers with controlled molecular weight and functionality and triblock polymers with segments with potentially interesting electronic properties. A series of new group VIII catalysts are being developed that allow a wide range of functionality to be incorporated into the polymer side chains. The same catalysts can also be used in the synthesis of fine chemicals.

  19. SCATTERING FROM RAMIFIED POLYMERIC SYSTEMS

    Directory of Open Access Journals (Sweden)

    M.Benhamou

    2004-01-01

    Full Text Available Here, of great interest to us is a quantitative study of the scattering properties from ramified polymeric systems of arbitrary topology. We consider three types of systems, namely ramified polymers in solution, ramified polymer blends, or ternary mixtures made of two ramified polymers of different chemical nature immersed in a good solvent. To achieve the goal of the study, use is made of the Random Phase Approximation. First we determine the exact expression of the form factor of an ideal ramified polymer of any topology, from which we extract the exact expression of its gyration radius. Using the classical Zimm's formulae and the exact form factor, we determine all scattering properties of these three types of ramified polymeric systems. The main conclusion is that ramification of the chains induces drastic changes of the scattering properties.

  20. Polymerization catalyst, production and use

    International Nuclear Information System (INIS)

    Best, S.A.

    1987-01-01

    A process is described for the polymerization of ethylene and alpha-olefins having from 1 to 2 carbon atoms of mixtures of ethylene, alpha-olefins or diolefins. The process comprises polymerizing one or more olefins in the presence of the catalyst system comprising (A) an organo aluminum cocatalyst, and (B) a vanadium-containing catalyst component obtained by sequentially treating an inert solid support material in an inert solvent with (i) a dihydrocarbyl magnesium compound, (ii) optionally an oxygen-containing compound which is an alcohol, ketone or aldehyde, (iii) a vanadium compound, and (iv) a Group IIIa metal halide. The process as above is described wherein the inert solid support material is an inorganic oxide or mixtures of inorganic oxides

  1. Sleeving nanocelluloses by admicellar polymerization.

    Science.gov (United States)

    Trovatti, Eliane; Ferreira, Adriane de Medeiros; Carvalho, Antonio José Felix; Ribeiro, Sidney José Lima; Gandini, Alessandro

    2013-10-15

    This investigation reports the first application of admicellar polymerization to cellulose nanofibers in the form of bacterial cellulose, microfibrillated cellulose, and cellulose nanowhiskers using styrene and ethyl acrylate. The success of this physical sleeving was assessed by SEM, FTIR, and contact angle measurements, providing an original and simple approach to the modification of cellulose nanofibers in their pristine aqueous environment. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  2. Polymeric Microspheres for Medical Applications

    Directory of Open Access Journals (Sweden)

    Ketie Saralidze

    2010-06-01

    Full Text Available Synthetic polymeric microspheres find application in a wide range of medical applications. Among other applications, microspheres are being used as bulking agents, embolic- or drug-delivery particles. The exact composition of the spheres varies with the application and therefore a large array of materials has been used to produce microspheres. In this review, the relation between microsphere synthesis and application is discussed for a number of microspheres that are used for different treatment strategies.

  3. Microwave-assisted ADMET polymerization

    OpenAIRE

    Rojas Jiménez, Giovanni

    2015-01-01

    Microwave-assisted ADMET polymerization is reported on a series of α,ω-diene monomers, both polar and non-polar. Investigations indicate that of the multiple microwave modes possible, constant power is the most advantageous, providing polymers up to M‾w=31,000g/mol. Molecular weight values are nearly triple in comparison with conventional oil bath heating. Polymers are characterized by NMR, GPC, TGA, and DSC. Microwave irradiation provides a highly controllable and energy efficient ADMET poly...

  4. Non-equilibrium supramolecular polymerization.

    Science.gov (United States)

    Sorrenti, Alessandro; Leira-Iglesias, Jorge; Markvoort, Albert J; de Greef, Tom F A; Hermans, Thomas M

    2017-09-18

    Supramolecular polymerization has been traditionally focused on the thermodynamic equilibrium state, where one-dimensional assemblies reside at the global minimum of the Gibbs free energy. The pathway and rate to reach the equilibrium state are irrelevant, and the resulting assemblies remain unchanged over time. In the past decade, the focus has shifted to kinetically trapped (non-dissipative non-equilibrium) structures that heavily depend on the method of preparation (i.e., pathway complexity), and where the assembly rates are of key importance. Kinetic models have greatly improved our understanding of competing pathways, and shown how to steer supramolecular polymerization in the desired direction (i.e., pathway selection). The most recent innovation in the field relies on energy or mass input that is dissipated to keep the system away from the thermodynamic equilibrium (or from other non-dissipative states). This tutorial review aims to provide the reader with a set of tools to identify different types of self-assembled states that have been explored so far. In particular, we aim to clarify the often unclear use of the term "non-equilibrium self-assembly" by subdividing systems into dissipative, and non-dissipative non-equilibrium states. Examples are given for each of the states, with a focus on non-dissipative non-equilibrium states found in one-dimensional supramolecular polymerization.

  5. Dispersion Polymerizations in Supercritical Carbon Dioxide

    Science.gov (United States)

    Desimone, J. M.; Maury, E. E.; Menceloglu, Y. Z.; McClain, J. B.; Romack, T. J.; Combes, J. R.

    1994-07-01

    Conventional heterogeneous dispersion polymerizations of unsaturated monomers are performed in either aqueous or organic dispersing media with the addition of interfacially active agents to stabilize the colloidal dispersion that forms. Successful stabilization of the polymer colloid during polymerization results in the formation of high molar mass polymers with high rates of polymerization. An environmentally responsible alternative to aqueous and organic dispersing media for heterogeneous dispersion polymerizations is described in which supercritical carbon dioxide (CO_2) is used in conjunction with molecularly engineered free radical initiators and amphipathic molecules that are specifically designed to be interfacially active in CO_2. Conventional lipophilic monomers, exemplified by methyl methacrylate, can be quantitatively (>90 percent) polymerized heterogeneously to very high degrees of polymerization (>3000) in supercritical CO_2 in the presence of an added stabilizer to form kinetically stable dispersions that result in micrometer-sized particles with a narrow size distribution.

  6. Rearrangement of micelle structures during polymerization

    International Nuclear Information System (INIS)

    Chatjaroenporn, K.; Baker, R.; FitzGerald, P.; Warr, G.

    2009-01-01

    Full text: Using small angle neutron scattering (SANS), we studied the shape transition of micelles of 11(methacryloyloxy)undecyltrimethylammonium bromide (MUTAB) as this tail-polymerisable cationic surfactant polymerized. Previous studies of such systems have suggested kinetic 'locking' of the micelle structure during polymerization. However, we found a transition from spheres (unpolymerised) to rods (at intermediate conversions) back to spheres (fully polymerized), see Figure 1. By comparing these results to the micelle shapes formed by the mixtures of 100% polymerized and unpolymerised MUTAB, we show that the shape transitions observed during polymerization are due to equilibrium structures that undergo rearrangement as the composition changes. In addition, atomic force microscopy (AFM) reveals that besides the monolayer of unpolymerised MUTAB, the rearranged structures of this surfmer in bulk, when polymerization proceeded, retained their shapes after adsorbing at mica/solution interface, providing potential for the manipulating of thin film structures. This understanding assists design of templating or encapsulating nanostructured materials.

  7. Thermal conductivity of pressure polymerized C60

    International Nuclear Information System (INIS)

    Soldatov, A.; Andersson, O.

    1997-01-01

    We have studied the kinetics of C 60 polymerization in the temperature interval 450-500 K at pressures below 1 GPa by measurements of the time dependence of the thermal conductivity. It has been found at 450 K that the polymerization process at 0.8 GPa is slower than the reverse transformation from ''polymeric'' to ''monomeric'' phase at 0.08 GPa. The thermal conductivity λ of polymerized C 60 was measured in the temperature range 100-430 K and found to increase with increasing temperature, which reflects strong phonon scattering. Both the presence of non-bonded C 60 molecules and a high degree of structural disorder in the crystalline lattice of the polymeric phase might be responsible for the behaviour of λ(T). The results for λ(T) are qualitatively similar to those reported previously for C 60 polymerized at higher p, T but an order of magnitude smaller. (orig.)

  8. Polymeric Micelles for Acyclovir Drug Delivery

    OpenAIRE

    Sawdon, Alicia J.; Peng, Ching-An

    2014-01-01

    Polymeric prodrug micelles for delivery of acyclovir (ACV) were synthesized. First, ACV was used directly to initiate ring-opening polymerization of ε-caprolactone to form ACV-polycaprolactone (ACV-PCL). Through conjugation of hydrophobic ACV-PCL with hydrophilic methoxy poly(ethylene glycol) (MPEG) or chitosan, polymeric micelles for drug delivery were formed. 1H NMR, FTIR, and gel permeation chromatography were employed to show successful conjugation of MPEG or chitosan to hydrophobic ACV-P...

  9. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu

    2012-05-02

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  10. Volumetric polymerization shrinkage of contemporary composite resins

    OpenAIRE

    Nagem Filho, Halim; Nagem, Haline Drumond; Francisconi, Paulo Afonso Silveira; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; Coutinho, Kennedy Queiroz

    2007-01-01

    The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill ...

  11. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization reactor, it is the best way to avoid any termination of living polymers during the number of steps for the synthesis of polymers with complex structure. In this chapter, we describe the different polymerization reactors and HVTs for the purification of monomers, solvents, and other reagents for anionic polymerization as well as few model reactions for the synthesis of polymers with simple to complex structure.

  12. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands for time and skilled technical personnel, HVTs are currently used in only a few research laboratories worldwide. Instead, most researchers in this filed are attracted to more facile Schlenk techniques. The basic principle of this technique followed in all laboratories is substantially the same, i.e. the use of alternate vacuum and inert gas atmosphere in glass apparatus for the purification/charging of monomer, solvents, additives, and for the manipulation of air-sensitive compounds such as alkyl metal initiators, organometallic or organic catalysts. However, it is executed quite differently in each research group in terms of the structure of Schlenk apparatus (manifolds, connections, purification/storage flasks, reactors, etc.), the use of small supplementary devices (soft tubing, cannulas, stopcocks, etc.) and experimental procedures. The operational methods are partly purpose-oriented while also featured by a high flexibility, which makes it impossible to describe in detail each specific one. In this chapter we will briefly exemplify the application of Schlenk techniques for anionic polymerization by describing the performance of a few experiments from our own work.

  13. Polymerized Paired Ions as Polymeric Ionic Liquid-Proton Conductivity.

    Science.gov (United States)

    Gu, Hong; Yan, Feng; Texter, John

    2016-07-01

    A new polymerized ionic liquid has been derived by photopolymerization of a stimuli-responsive ionic liquid surfactant, ILAMPS, which is composed of polymerizable, paired ions. The cation is 1-methyl-3-[11-(acryloyloxy)undecyl] imidazolium (IL), and the anion is 2-acrylamido-2-methyl-1-propanesulfonate (AMPS). This ion combination is a new ionic liquid. The resulting hygroscopic resins are highly polarizable, suitable for sensor design and for ultracapacitor fabrication and proton conducting. Interactions of imidazolium with anions provide basis for stimuli-responsiveness, and are used to promote proton transport. Doping with one equivalent of HPF6 at 0% relative humidity produces a 100-fold increase in proton conductivity at 100-125 °C and activation energies for proton transport lower than those of Nafion at water loadings less than 5 per sulfonate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Thermal bulk polymerization of cholesteryl acrylate

    NARCIS (Netherlands)

    de Visser, A.C.; de Groot, K.; Feijen, Jan; Bantjes, A.

    1971-01-01

    The thermal bulk polymerization of cholesteryl acrylate was carried out in the solid phase, the mesomorphic phase, and the liquid phase to study the effect of monomer ordering on polymerization rate and polymer properties. The rate increased with decreasing ordering (or enhanced mobility) of the

  15. Polymeric implant of methylprednisolone for spinal injury ...

    African Journals Online (AJOL)

    Polymeric implant of methylprednisolone for spinal injury: preparation and characterization. Bo Yin, Jian-Jun Ji, Ming Yang. Abstract. Purpose: To improve the effectiveness and reduce the systemic side effects of methylprednisolone in traumatic spinal injuries, its polymeric implants were prepared using chitosan and sodium ...

  16. Transformation kinetics of mixed polymeric substrates under ...

    African Journals Online (AJOL)

    Transformation kinetics of mixed polymeric substrates under transitory conditions by Aspergillus niger. ... Abstract. A mixture of polymeric substrates (simulating a complex wastewater) was transformed under sewer conditions and aerobiosis by Aspergillus niger in a tanks-in-series reactor at a hydraulic retention time of 14 h.

  17. Effective thermal conductivity of condensed polymeric nanofluids ...

    Indian Academy of Sciences (India)

    Polymeric nanosolids; thermal conductivity; photothermal techniques; effective medium theory; interfacial scattering. PACS Nos 66.70.−f; 65.80.−g; 81.07.−b; 66.70.Hk. 1. Introduction. The polymeric nanosolids presented in this work are uniform dispersions of a single-phase nanomaterial dispersed uniformly in a polymer ...

  18. Sodium metabisulphite induced polymerization of sickle cell ...

    African Journals Online (AJOL)

    The present in vitro study ascertained the capacity of three medicinal plants, namely, Anacardium occidentale, Psidium guajava and Terminalia catappa, to alter polymerization of sickle cell haemoglobin (HbS). Spectrophotometric method was used to monitor the level of polymerization of haemolysate HbS molecules ...

  19. Nanoparticles from a controlled polymerization process

    International Nuclear Information System (INIS)

    Tirumala, V.R.; Caneba, G.T.; Dar, Y.; Wang, H.-H.; Mancini, D.C.

    2003-01-01

    Free-radical retrograde precipitation polymerization process in the past has shown excellent control characteristics over reaction rate, molecular weight, and in the entrapment of live radicals for the generation of block copolymers. The same principle has now been extended to study the reaction confinement to a nanoscale region. Nanosized polymer particles have been reported to form from block copolymers, conventional precipitation polymerization methods, or through emulsion polymerization approaches. In this work, we present a new method of generating nanosized polymer particles by polymerizing the monomer in an environment that precipitates the polymer above the lower critical solution temperature. The nanoparticles have been characterized by both tapping-mode atomic force microscopy observations and in situ synchrotron time-resolved small-angle X-ray scattering analysis. The results from both the techniques showed the formation of nanoparticles in the size range of 15-30 nm, directly from the polymerization process.

  20. Ecotoxicological effects evoked in hydrophytes by leachates of invasive Acer negundo and autochthonous Alnus glutinosa fallen off leaves during their microbial decomposition.

    Science.gov (United States)

    Krevš, Alina; Darginavičienė, Jūratė; Gylytė, Brigita; Grigutytė, Reda; Jurkonienė, Sigita; Karitonas, Rolandas; Kučinskienė, Alė; Pakalnis, Romas; Sadauskas, Kazys; Vitkus, Rimantas; Manusadžianas, Levonas

    2013-02-01

    Throughout 90-day biodegradation under microaerobic conditions, invasive to Lithuania species boxelder maple (Acer negundo) leaves lost 1.5-fold more biomass than that of autochthonous black alder (Alnus glutinosa), releasing higher contents of N(tot), ammonium and generating higher BOD(7). Boxelder maple leaf leachates were characterized by higher total bacterial numbers and colony numbers of heterotrophic and cellulose-decomposing bacteria than those of black alder. The higher toxicity of A. negundo aqueous extracts and leachates to charophyte cell (Nitellopsis obtusa), the inhabitant of clean lakes, were manifested at mortality and membrane depolarization levels, while the effect on H(+)-ATPase activity in membrane preparations from the same algae was stronger in case of A. glutinosa. Duckweed (Lemna minor), a bioindicator of eutrophic waters, was more sensitive to leaf leachates of A. glutinosa. Fallen leaves and leaf litter leachates from invasive and native species of trees, which enter water body, affect differently microbial biodestruction and aquatic vegetation in freshwater systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Analisis Peta Persepsi Pemilihan Atribut Produk Laptop Di Kalangan Mahasiswa Universitas Telkom Kota Bandung (Studi Pada Laptop Acer, Asus, Lenovo, Toshiba, HP, Samsung dan Apple

    Directory of Open Access Journals (Sweden)

    Wiwik Melwinda

    2017-04-01

    Full Text Available This research aims to find out laptop brand selection perceptual map of among Telkom University students. The object of this research study are some of incoming laptop brand in Top Brand 2016 which are Acer, Lenovo, Asus, Toshiba, HP, Samsung and Apple. The attributes of the study are design instrument, operation system, variation, feature set, specification, processor, battery resistance, product price, price resale, warranty, LCD display, storage capacity, product quality, sustainability to defect, and keyboard quality. This research used quantitative method. Research instrument used was a questionnaire, which distributed to 100 respondent sample area of the object of research. In taking a sample of this study, the researcher used Non-Probability technique by using purposive sampling method. The data analysis that used is multidimensional scalling analysis, this analysis gives perception map picture, appeared the position of each laptop brand that is close together or far apart. Laptop brand that showed in a perceptual map will display rank of the best position than another laptop brand. As perception, Apple occupies the first best position among another best laptop brands. That is proved by the rank position from respondents preference based on overall attributes which is more excellent in design, operation system, variation, feature set, specification, processor, battery resistance, product quality, and keyboard quality. For price product attribute is occupied by Lenovo as the cheapest rather than another laptop brands. Meanwhile, for the LCD display attribute, price resale, and storage capacity are occupied by Asus which get the second best rank based overall attribute.

  2. Influence of invasive Acer negundo leaf litter on benthic microbial abundance and activity in the littoral zone of a temperate river in Lithuania

    Directory of Open Access Journals (Sweden)

    Krevš Alina

    2017-01-01

    Full Text Available Riparian forests are known as important source of allochthonous organic matter entering to water ecosystems via fallen leaves. However, leaf litter, depending on their quality, may create different conditions for benthic microorganisms functioning in littoral zone of water bodies. In order to evaluate the impact of riparian invasive Acer negundo on littoral water zone of the River Neris (Lithuania, we performed physicochemical and microbiological investigations in bottom sediments of three different sites of the river. One sampling site was close by riparian A. negundo, another close by native Alnus glutinosa location and a third zone was near the shore without riparian vegetation. Content of nutrients in the littoral sediments differed between invasive and native trees leaf litter accumulation sites, while not always significantly. The highest microbial densities as well as benthic community respiratory activity (expressed as the rate of organic carbon mineralization occurred in A. negundo leaves accumulation site. In sediments of this site, the most intensive anaerobic terminal organic carbon mineralization process − sulfate reduction and the highest concentration of hydrogen sulfide were also observed. Differences in the intensity of mineralization processes between sites suggest that the replacement of the riparian native species such as dominant A. glutinosa by invasive A. negundo with higher biodegradability leaves may induce local changes in organic matter processing in the littoral zone of the river. The increase of littoral bioproductivity in the accumulation zone of A. negundo leaf litter can occur due to the inflow of available organic matter and its intensive mineralization.

  3. Comparative measurements of transpiration an canopy conductance in two mixed deciduous woodlands differing in structure and species composition

    DEFF Research Database (Denmark)

    Herbst, Mathias; Rosier, Paul T.W.; Morecroft, Michael D.

    2008-01-01

    a continuous hazel (Corylus avellana L.) understory. Wytham Woods, which had an LAI of 3.6, was dominated by ash (Fraxinus excelsior L.) and sycamore (Acer pseudoplatanus L.) and had only a sparse understory. Annual canopy transpiration was 367 mm for Grimsbury Wood and 397 mm for Wytham Woods. These values...

  4. Hypoglycin A Concentrations in Maple Tree Species in the Netherlands and the Occurrence of Atypical Myopathy in Horses

    NARCIS (Netherlands)

    Westermann, C.M.; Van Leeuwen, Robbert; Van Raamsdonk, L.W.D.; Mol, H.G.J.

    BACKGROUND: Atypical myopathy (AM) in horses is caused by the plant toxin hypoglycin A, which in Europe typically is found in the sycamore maple tree (Acer pseudoplatanus). Owners are concerned about whether their horses are in danger if they graze near maple trees. HYPOTHESIS/OBJECTIVES: To measure

  5. Hypoglycin A Concentrations in Maple Tree Species in the Netherlands and the Occurrence of Atypical Myopathy in Horses

    NARCIS (Netherlands)

    Westermann, C.M.; Leeuwen, van R.; Raamsdonk, van L.W.D.; Mol, H.G.J.

    2016-01-01

    Background: Atypical myopathy (AM) in horses is caused by the plant toxin hypoglycin A, which in Europe typically is found in the sycamore maple tree (Acer pseudoplatanus). Owners are concerned about whether their horses are in danger if they graze near maple trees. Hypothesis/Objectives: To

  6. Metal uptake by young trees from dredged brackish sediment : Limitations and possibilities for phytoextraction and phytostabilisation

    NARCIS (Netherlands)

    Mertens, Jan; Vervaeke, Pieter; de Schrijver, A.; Luyssaert, Sebastiaan

    2004-01-01

    Five tree species (Acer pseudoplatanus L., Alnus glutinosa L. Gaertn., Fraxinus excelsior L., Populus alba L. and Robinia pseudoacacia L.) were planted on a mound constructed of dredged sediment. The sediment originated from a brackish river mouth and was slightly polluted with heavy metals. This

  7. Polymerization of lanthanide acrylonitrile complexes.

    Science.gov (United States)

    el-Mossalamy, El-Sayed H; Khalil, Ahmed A

    2002-01-01

    The molecular complexes of some lanthanides scandium (Sc3+), yttrium (Y3+), lanthanum (La3+), gadolinium (Gd3+), cerium (Ce3+) and ytterbium (Yb3) have been studies in dimethyl formamide (DMF) spectrophtometrically equilibrium constants (K), molar extintion coefficient (epsilon), energy of transition (E) and free energy (delta G*) were calculated. The polymerization of acrylonitrile has been studied and investigated in the presence of Sc3+, Y3+, La3+, Gd3+, Ce3+, and Yb3+ ions. The IR spectra of the formed AN-M (III) Br3 polymer complexes show the absence of the C identical to N band and the presence of two new bands corresponding to NH2 and OH groups. Magnetic moment values and the thermal stabilities of homopolymer and the polymer complexes were studied by means of thermogravimetric analysis and the activation energies for degradation were calculated.

  8. Polymeric materials from renewable resources

    Science.gov (United States)

    Frollini, Elisabete; Rodrigues, Bruno V. M.; da Silva, Cristina G.; Castro, Daniele O.; Ramires, Elaine C.; de Oliveira, Fernando; Santos, Rachel P. O.

    2016-05-01

    The goals of our studies have been the use of renewable raw materials in the preparation of polymeric materials with diversified properties. In this context, lignosulfonate, which is produced in large scale around the world, but not widely used in the production of polymeric materials, was used to replace phenol and polyols in the preparation of phenolic- (Ligno-PH) and polyurethane-type (Ligno-PU) polymers, respectively. These polymers were used to prepare composites reinforced with sisal lignocellulosic fibers. The use of lignosulfonate in the formulation of both types of polymers was beneficial, because in general composites with improved properties, specially impact strength, were obtained. Composites were also prepared from the so called "biopolyethylene" (HDPE), curaua lignocellulosic fiber, and castor oil (CO). All composites HDBPE/CO/Fiber exhibited higher impact strength, when compared to those of the corresponding HDBPE/Fiber. These results, combined with others (eg SEM images of the fractured surfaces) indicated that, in addition to acting as a plasticizer, this oil may have acted as a compatibilizer of the hydrophilic fiber with the hydrophobic polymer. The set of results indicated that (i) mats with nano (diameter ≤ 100nm) and/or ultrafine (submicron scale) fibers were produced, (ii) hybrid fibers were produced (bio-based mats composites), (iii) cellulosic pulp (CP) and/or lignin (Lig) can be combined with PET matrices to control properties such as stiffness and hydrophilicity of the respective mats. Materials with diversified properties were prepared from high content of renewable raw materials, thus fulfilling the proposed targets.

  9. Polymeric materials from renewable resources

    Energy Technology Data Exchange (ETDEWEB)

    Frollini, Elisabete; Rodrigues, Bruno V. M.; Silva, Cristina G. da; Castro, Daniele O.; Ramires, Elaine C.; Oliveira, Fernando de; Santos, Rachel P. O. [Macromolecular Materials and Lignocellulosic Fibers Group, Center for Research on Science and Technology of BioResources, Institute of Chemistry of São Carlos, University of São Paulo, CP 780, 13560-970 São Carlos, São Paulo (Brazil)

    2016-05-18

    The goals of our studies have been the use of renewable raw materials in the preparation of polymeric materials with diversified properties. In this context, lignosulfonate, which is produced in large scale around the world, but not widely used in the production of polymeric materials, was used to replace phenol and polyols in the preparation of phenolic- (Ligno-PH) and polyurethane-type (Ligno-PU) polymers, respectively. These polymers were used to prepare composites reinforced with sisal lignocellulosic fibers. The use of lignosulfonate in the formulation of both types of polymers was beneficial, because in general composites with improved properties, specially impact strength, were obtained. Composites were also prepared from the so called “biopolyethylene” (HDPE), curaua lignocellulosic fiber, and castor oil (CO). All composites HDBPE/CO/Fiber exhibited higher impact strength, when compared to those of the corresponding HDBPE/Fiber. These results, combined with others (eg SEM images of the fractured surfaces) indicated that, in addition to acting as a plasticizer, this oil may have acted as a compatibilizer of the hydrophilic fiber with the hydrophobic polymer. The set of results indicated that (i) mats with nano (diameter ≤ 100nm) and/or ultrafine (submicron scale) fibers were produced, (ii) hybrid fibers were produced (bio-based mats composites), (iii) cellulosic pulp (CP) and/or lignin (Lig) can be combined with PET matrices to control properties such as stiffness and hydrophilicity of the respective mats. Materials with diversified properties were prepared from high content of renewable raw materials, thus fulfilling the proposed targets.

  10. Radiation polymerization of vinylene carbonate

    International Nuclear Information System (INIS)

    Schnautz, N.G.; Lustig, A.; Roesch, H.

    1978-05-01

    The radiation-induced polymerization of vinylene carbonate of 99,97% purity has been investigated. The relationship between conversion and irradiation time is strictly linear, even at the lowest conversions, thus proving that the normal induction period observed for the polymerization of lower-purity vinylene carbonate indeed results from the presence of an inhibitor. Although the identity of the inhibitor has not been established, it has been shown that it is not dichlorovinylene carbonate. An activation energy of 15,1 kJ/mole was calculated for the homopolymerization process. The radiation-induced copolymerization of vinylene carbonate (M 1 ) with isobutyl vinyl ether (M 2 ) has been investigated over the temperature range of 40-80 degrees Celcius. The monomer reactivity ratios r 1 and r 2 were determined to be 0,118 and 0,148 respectively, and an activation energy of 31,8kJ/mole was calculated for the copolymerization process. The radiation-induced telomerization of vinylene carbonate with carbon tetrachloride has been investigated over a telogen to monomer concentration ratio range of 4 to 20. The rate of formation of the n=1 adduct was found to be independent of monomer concentration, directly proportional to the telogen concentration, and exhibiting a 0,38 order power dependence on the radiation intensity, in general agreement with the derived rate equations. The rate of formation of the n=2 telomer was found to be independent of both monomer and telogen concentrations and radiation intensity, which is not in agreement with the derived rate equations. The first and second chain-transfer coefficients C 1 and C 2 were determined to be 0,116 and 0,34 respectively, and the activation energies for the formation of the n=1 adduct and n=2 telomer were calculated to be 17,6 and 64,9 kJ/mole respectively [af

  11. Ion transport phenomena in polymeric electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Ciosek, M.; Sannier, L.; Siekierski, M.; Wieczorek, W. [Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, 00-664 Warsaw (Poland); Golodnitsky, D.; Peled, E. [School of Chemistry, Tel Aviv University, Tel Aviv 69978 (Israel); Scrosati, B. [Dipartimento di Chimica, Universita di Roma ' ' La Sapienza' ' , P. le A. Moro 4, 00185 Rome (Italy); Glowinkowski, S. [Faculty of Physics, Adam Mickiewicz University, Ulmultowska 86, 61-614 Poznan (Poland)

    2007-12-31

    The aim of the present work is to generalize an ion transport phenomena observed in composite polymeric electrolytes using the previously developed models as well as design a new approach which would be helpful in describing changes in conductivity and lithium ion transference numbers occurring upon addition of fillers to polymeric electrolytes. The concept is based on the observation of changes in ionic associations in the polymeric electrolytes studied in a wide salt concentration range. The idea is illustrated by the results coming from a variety of electrochemical and structural data obtained for composite electrolytes containing specially designed inorganic and organic fillers. (author)

  12. Radiation induced emulsion polymerization of vinylidene chloride

    International Nuclear Information System (INIS)

    Panajkar, M.S.; Rao, K.N.

    1979-01-01

    Gamma ray induced emulsion polymerization of vinylidene chloride has been carried out and the percent conversion of monomer to polymer and molecular weights of emulsion polymer were measured as a function of time and emulsifier concentration. Rp was found to be dependent on 0.3 power of emulsifier concentration whereas molecular weights increased with conversion and emulsifier concentration. The number of particles N also increased with conversion contrary to Smith Ewart's theory of emulsion polymerization. The results are discussed in the light of existing theories of emulsion polymerization. (author)

  13. Hypoglycin A Concentrations in Maple Tree Species in the Netherlands and the Occurrence of Atypical Myopathy in Horses.

    Science.gov (United States)

    Westermann, C M; van Leeuwen, R; van Raamsdonk, L W D; Mol, H G J

    2016-05-01

    Atypical myopathy (AM) in horses is caused by the plant toxin hypoglycin A, which in Europe typically is found in the sycamore maple tree (Acer pseudoplatanus). Owners are concerned about whether their horses are in danger if they graze near maple trees. To measure hypoglycin A in the most common maple tree species in the Netherlands, and to determine whether concentration of toxin is a predictor of AM in horses. A total of 278 samples of maple tree leaves, sprouts, and seeds were classified by species. Mean concentrations of hypoglycin A were compared for the type of sample, the season and the occurrence of AM in the pasture (non-AM versus AM). Statistical analysis was performed using generalized a linear model (SPPS22). Almost all Acer pseudoplatanus samples contained hypoglycin A, with concentrations differing significantly among sources (P < .001). Concentrations were significantly higher in seeds from the AM group than in seeds from the non-AM group (856 ± 677 and 456 ± 358 mg/kg, respectively; P = .039). In sprouts and leaves this was not the case. Acer platanoides and Acer campestre samples did not contain detectable concentrations of hypoglycin A. Acer platanoides and campestre seem to be safe around paddocks and pastures, whereas almost all Acer pseudoplatanus samples contained hypoglycin A. In all AM cases, Acer pseudoplatanus was found. Despite significantly higher concentration of hypoglycin A in seeds of pastures where AM has occurred, individual prediction of AM cannot be made by measuring these concentrations because of the high standard deviation. Copyright © 2016 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

  14. Deformation and flow of polymeric materials

    CERN Document Server

    Münstedt, Helmut

    2014-01-01

    This book describes the properties of single polymer molecules and polymeric materials and the methods how to characterize them. Molar masses, molar mass distributions and branching structure are discussed in detail. These properties are decisive for a deeper understanding of structure/properties relationships of polymeric materials. This book therefore describes and discusses them in detail. The mechanical behavior as a function of time and temperature is a key subject of the book. The authors present it on the basis of many original results they have obtained in their long research careers. They present the temperature dependence of mechanical properties of various polymeric materials in a wide temperature range: from cryogenic temperatures to the melt. Besides an extensive data collection on the transitions of various different polymeric materials, they also carefully present the physical explanations of the observed phenomena. Glass transition and melting temperatures are discussed, particularly, with the...

  15. Thermal polymerization of Moringa oleifera oil

    International Nuclear Information System (INIS)

    Melo, Tania M.S.; Novack, Katia M.; Leandro, Cristiano

    2011-01-01

    It is increasingly clear both for society and the scientific community, that is necessary to find alternatives to reduce the use of polymeric materials because of their damage to the environment. One way to minimize the environmental problems related to the use of polymers is try to make them quickly degradable. In this study it was obtained a material with polymeric appearance derived from heating of the vegetable oil extracted from seeds of Moringa oleifera. The resulting product is an interesting alternative to obtain polymeric materials that may have biodegradable characteristics, coming from a renewable source and low cost. Moringa oil can be used since it has a high content of unsaturated fatty acids, and its main constituent oleic acid. All samples were characterized by FTIR, NMR and GPC. It was obtained a polymeric material, malleable, high viscosity, with some elasticity, low crystallinity and no unpleasant odor. (author)

  16. Compression Behavior of High Performance Polymeric Fibers

    National Research Council Canada - National Science Library

    Kumar, Satish

    2003-01-01

    Hydrogen bonding has proven to be effective in improving the compressive strength of rigid-rod polymeric fibers without resulting in a decrease in tensile strength while covalent crosslinking results in brittle fibers...

  17. Physicochemically functional ultrathin films by interfacial polymerization

    Science.gov (United States)

    Lonsdale, Harold K.; Babcock, Walter C.; Friensen, Dwayne T.; Smith, Kelly L.; Johnson, Bruce M.; Wamser, Carl C.

    1990-01-01

    Interfacially-polymerized ultrathin films containing physicochemically functional groups are disclosed, both with and without supports. Various applications are disclsoed, including membrane electrodes, selective membranes and sorbents, biocompatible materials, targeted drug delivery, and narrow band optical absorbers.

  18. Reverse-osmosis membranes by plasma polymerization

    Science.gov (United States)

    Hollahan, J. R.; Wydeven, T.

    1972-01-01

    Thin allyl amine polymer films were developed using plasma polymerization. Resulting dry composite membranes effectively reject sodium chloride during reverse osmosis. Films are 98% sodium chloride rejective, and 46% urea rejective.

  19. Polymerization of sodium methacrylate induced by irradiation

    International Nuclear Information System (INIS)

    Galvan S, A.

    1998-01-01

    This work has two objectives, first: it is pretended to localize the lines of carbon links in its IR spectra, and second: following the polymerization of sodium methacrylate according to that it is irradiated with gamma rays. (Author)

  20. Transformation kinetics of mixed polymeric substrates under ...

    African Journals Online (AJOL)

    bglucosidase and a-mannosidase were abundantly secreted in the growth medium. This research is the first report on mixed polymeric substrate biodegradation under sewer condition by A. niger, and could be considered as an open window on ...

  1. Characterization of Polymeric Nanofiltration Membranes

    Directory of Open Access Journals (Sweden)

    Simoncic, B.

    2007-11-01

    Full Text Available As membrane processes are increasingly used in industrial applications, there is a growing interest in methods of membrane characterization. Traditional membrane characteristics, such as cut-off value and pore size distribution, are being supplemented by membrane surface characteristics, such as charge density or zeta potential and hydrophobicity. This study, therefore, characterizes the three different polymeric membranes used (NFT-50, DL and DK. The molecular mass cut-off (MMCO value was determined using a set of reference solutes within the molecular range 150-600 Da, whereas streaming potential measurements enabled quantification of the surface charge characteristics. Hydrophobicity was studied using contact angle measurements. The results indicated that even though all three membranes had very similar layer compositions which consisted of poly(piperazneamide, as top layers they showed different values of measured quantitive. The NFT-50 membrane had the lowest MMCO value and the most hydrophilic membrane surface, followed by DK and DL. Membrane fouling as measured by flux reduction was determined by streaming potential measurements and accompanied by a positive change in zeta potential.

  2. Highly elastic conductive polymeric MEMS

    Science.gov (United States)

    Ruhhammer, J.; Zens, M.; Goldschmidtboeing, F.; Seifert, A.; Woias, P.

    2015-02-01

    Polymeric structures with integrated, functional microelectrical mechanical systems (MEMS) elements are increasingly important in various applications such as biomedical systems or wearable smart devices. These applications require highly flexible and elastic polymers with good conductivity, which can be embedded into a matrix that undergoes large deformations. Conductive polydimethylsiloxane (PDMS) is a suitable candidate but is still challenging to fabricate. Conductivity is achieved by filling a nonconductive PDMS matrix with conductive particles. In this work, we present an approach that uses new mixing techniques to fabricate conductive PDMS with different fillers such as carbon black, silver particles, and multiwalled carbon nanotubes. Additionally, the electrical properties of all three composites are examined under continuous mechanical stress. Furthermore, we present a novel, low-cost, simple three-step molding process that transfers a micro patterned silicon master into a polystyrene (PS) polytetrafluoroethylene (PTFE) replica with improved release features. This PS/PTFE mold is used for subsequent structuring of conductive PDMS with high accuracy. The non sticking characteristics enable the fabrication of delicate structures using a very soft PDMS, which is usually hard to release from conventional molds. Moreover, the process can also be applied to polyurethanes and various other material combinations.

  3. Physiological and foliar symptom response in the crowns of Prunus serotina, Fraxinus americana and Acer rubrum canopy trees to ambient ozone under forest conditions

    International Nuclear Information System (INIS)

    Schaub, M.; Skelly, J.M.; Zhang, J.W.; Ferdinand, J.A.; Savage, J.E.; Stevenson, R.E.; Davis, D.D.; Steiner, K.C.

    2005-01-01

    The crowns of five canopy dominant black cherry (Prunus serotina Ehrh.), five white ash (Fraxinus americana L.), and six red maple (Acer rubrum L.) trees on naturally differing environmental conditions were accessed with scaffold towers within a mixed hardwood forest stand in central Pennsylvania. Ambient ozone concentrations, meteorological parameters, leaf gas exchange and leaf water potential were measured at the sites during the growing seasons of 1998 and 1999. Visible ozone-induced foliar injury was assessed on leaves within the upper and lower crown branches of each tree. Ambient ozone exposures were sufficient to induce typical symptoms on cherry (0-5% total affected leaf area, LAA), whereas foliar injury was not observed on ash or maple. There was a positive correlation between increasing cumulative ozone uptake (U) and increasing percent of LAA for cherry grown under drier site conditions. The lower crown leaves of cherry showed more severe foliar injury than the upper crown leaves. No significant differences in predawn leaf water potential (ψ L ) were detected for all three species indicating no differing soil moisture conditions across the sites. Significant variation in stomatal conductance for water vapor (g wv ) was found among species, soil moisture, time of day and sample date. When comparing cumulative ozone uptake and decreased photosynthetic activity (P n ), red maple was the only species to show higher gas exchange under mesic vs. drier soil conditions (P wv and P n demonstrate the strong influence of heterogeneous environmental conditions within forest canopies. - Within the heterogeneous environment of a mature forest, many factors in addition to soil moisture play a significant role in determining exposure/response relationships to ozone

  4. Effects of elevated [CO2] and low soil moisture on the physiological responses of Mountain Maple (Acer spicatum L. seedlings to light.

    Directory of Open Access Journals (Sweden)

    Gabriel Danyagri

    Full Text Available Global climate change is expected to affect how plants respond to their physical and biological environments. In this study, we examined the effects of elevated CO2 ([CO2] and low soil moisture on the physiological responses of mountain maple (Acer spicatum L. seedlings to light availability. The seedlings were grown at ambient (392 µmol mol(-1 and elevated (784 µmol mol(-1 [CO2], low and high soil moisture (M regimes, at high light (100% and low light (30% in the greenhouse for one growing season. We measured net photosynthesis (A, stomatal conductance (g s, instantaneous water use efficiency (IWUE, maximum rate of carboxylation (V cmax, rate of photosynthetic electron transport (J, triose phosphate utilization (TPU, leaf respiration (R d, light compensation point (LCP and mid-day shoot water potential (Ψx. A and g s did not show significant responses to light treatment in seedlings grown at low soil moisture treatment, but the high light significantly decreased the C i/C a in those seedlings. IWUE was significantly higher in the elevated compared with the ambient [CO2], and the effect was greater at high than the low light treatment. LCP did not respond to the soil moisture treatments when seedlings were grown in high light under both [CO2]. The low soil moisture significantly reduced Ψx but had no significant effect on the responses of other physiological traits to light or [CO2]. These results suggest that as the atmospheric [CO2] rises, the physiological performance of mountain maple seedlings in high light environments may be enhanced, particularly when soil moisture conditions are favourable.

  5. Analytical approaches to the determination of simple biophenols in forest trees such as Acer (maple), Betula (birch), Coniferus, Eucalyptus, Juniperus (cedar), Picea (spruce) and Quercus (oak).

    Science.gov (United States)

    Bedgood, Danny R; Bishop, Andrea G; Prenzler, Paul D; Robards, Kevin

    2005-06-01

    Analytical methods are reviewed for the determination of simple biophenols in forest trees such as Acer (maple), Betula (birch), Coniferus, Eucalyptus, Juniperus (cedar), Picea (spruce) and Quercus (oak). Data are limited but nevertheless clearly establish the critical importance of sample preparation and pre-treatment in the analysis. For example, drying methods invariably reduce the recovery of biophenols and this is illustrated by data for birch leaves where flavonoid glycosides were determined as 12.3 +/- 0.44 mg g(-1) in fresh leaves but 9.7 +/- 0.35 mg g(-1) in air-dried samples (data expressed as dry weight). Diverse sample handling procedures have been employed for recovery of biophenols. The range of biophenols and diversity of sample types precludes general procedural recommendations. Caution is necessary in selecting appropriate procedures as the high reactivity of these compounds complicates their analysis. Moreover, our experience suggests that their reactivity is very dependent on the matrix. The actual measurement is less contentious and high performance separation methods particularly liquid chromatography dominate analyses whilst coupled techniques involving electrospray ionization are becoming routine particularly for qualitative applications. Quantitative data are still the exception and are summarized for representative species that dominate the forest canopy of various habitats. Reported concentrations for simple phenols range from trace level (<0.1 microg g(-1)) to in excess of 500 microg g(-1) depending on a range of factors. Plant tissue is one of these variables but various biotic and abiotic processes such as stress are also important considerations.

  6. Simulated root dynamics of a 160-year-old sugar maple (Acer saccharum Marsh.) tree with and without ozone exposure using the TREGRO model.

    Science.gov (United States)

    Retzlaff, W. A.; Weinstein, D. A.; Laurence, J. A.; Gollands, B.

    1996-01-01

    Because of difficulties in directly assessing root responses of mature forest trees exposed to atmospheric pollutants, we have used the model TREGRO to analyze the effects of a 3- and a 10-year exposure to ozone (O(3)) on root dynamics of a simulated 160-year-old sugar maple (Acer saccharum Marsh.) tree. We used existing phenological, allometric, and growth data to parameterize TREGRO to produce a simulated 160-year-old tree. Simulations were based on literature values for sugar maple fine root production and senescence and the photosynthetic responses of sugar maple seedlings exposed to O(3) in open-top chambers. In the simulated 3-year exposure to O(3), 2 x ambient atmospheric O(3) concentrations reduced net carbon (C) gain of the 160-year-old tree. This reduction occurred in the C storage pools (total nonstructural carbohydrate, TNC), with most of the reduction occurring in coarse (woody) roots. Total fine root production and senescence were unaffected by the simulated 3-year exposure to O(3). However, extending the simulated O(3) exposure period to 10 years depleted the TNC pools of the coarse roots and reduced total fine root production. Similar reductions in TNC pools have been observed in forest-grown sugar maple trees exhibiting symptoms of stress. We conclude that modeling can aid in evaluating the belowground response of mature forest trees to atmospheric pollution stress and could indicate the potential for gradual deterioration of tree health under conditions of long-term stress, a situation similar to that underlying the decline of sugar maple trees.

  7. Levels of selected trace elements in Scots pine (Pinus sylvestris L.), silver birch (Betula pendula L.), and Norway maple (Acer platanoides L.) in an urbanized environment.

    Science.gov (United States)

    Kosiorek, Milena; Modrzewska, Beata; Wyszkowski, Mirosław

    2016-10-01

    The aim of the study was to determine the concentrations of selected trace elements in needles and bark of Scots pine (Pinus sylvestris L.), leaves and bark of silver birch (Betula pendula L.), and Norway maple (Acer platanoides L.), as well as in the soil in which the trees grew, depending on their localization and hence the distribution of local pollution sources. The content of trace elements in needles of Scots pine, leaves of silver birch, and Norway maple and in bark of these trees depended on the location, tree species, and analyzed organ. The content of Fe, Mn, and Zn in needles, leaves, and bark of the examined tree species was significantly higher than that of the other elements. The highest average content of Fe and Mn was detected in leaves of Norway maple whereas the highest average content of Zn was found in silver birch leaves. The impact of such locations as the center of Olsztyn or roadside along Road 51 on the content of individual elements tended to be more pronounced than the influence of the other locations. The influence of the sampling sites on the content of trace elements in tree bark was less regular than the analogous effect in needles and leaves. Moreover, the relevant dependences were slightly different for Scots pine than for the other two tree species. The concentrations of heavy metals determined in the soil samples did not exceed the threshold values set in the Regulation of the Minister for the Environment, although the soil along Road 51 and in the center of Olsztyn typically had the highest content of these elements. There were also significant correlations between the content of some trace elements in soil and their accumulation in needles, leaves, and bark of trees.

  8. Effects of elevated [CO2] and low soil moisture on the physiological responses of Mountain Maple (Acer spicatum L.) seedlings to light.

    Science.gov (United States)

    Danyagri, Gabriel; Dang, Qing-Lai

    2013-01-01

    Global climate change is expected to affect how plants respond to their physical and biological environments. In this study, we examined the effects of elevated CO2 ([CO2]) and low soil moisture on the physiological responses of mountain maple (Acer spicatum L.) seedlings to light availability. The seedlings were grown at ambient (392 µmol mol(-1)) and elevated (784 µmol mol(-1)) [CO2], low and high soil moisture (M) regimes, at high light (100%) and low light (30%) in the greenhouse for one growing season. We measured net photosynthesis (A), stomatal conductance (g s), instantaneous water use efficiency (IWUE), maximum rate of carboxylation (V cmax), rate of photosynthetic electron transport (J), triose phosphate utilization (TPU)), leaf respiration (R d), light compensation point (LCP) and mid-day shoot water potential (Ψx). A and g s did not show significant responses to light treatment in seedlings grown at low soil moisture treatment, but the high light significantly decreased the C i/C a in those seedlings. IWUE was significantly higher in the elevated compared with the ambient [CO2], and the effect was greater at high than the low light treatment. LCP did not respond to the soil moisture treatments when seedlings were grown in high light under both [CO2]. The low soil moisture significantly reduced Ψx but had no significant effect on the responses of other physiological traits to light or [CO2]. These results suggest that as the atmospheric [CO2] rises, the physiological performance of mountain maple seedlings in high light environments may be enhanced, particularly when soil moisture conditions are favourable.

  9. Optimization of ultrasonic circulating extraction of samara oil from Acer saccharum using combination of Plackett-Burman design and Box-Behnken design.

    Science.gov (United States)

    Chen, Fengli; Zhang, Qiang; Fei, Shimin; Gu, Huiyan; Yang, Lei

    2017-03-01

    In this study, ultrasonic circulating extraction (UCE) technique was firstly and successfully applied for extraction of samara oil from Acer saccharum. The extraction kinetics were fitted and described, and the extraction mechanism was discussed. Through comparison, n-hexane was selected as the extraction solvent, the influence of solvent type on the responses was detailedly interpreted based on the influence of their properties on the occurrence and intensity of cavitation. Seven parameters potentially influencing the extraction yield of samara oil and content of nervonic acid, including ultrasound irradiation time, ultrasound irradiation power, ultrasound temperature, liquid-solid ratio, soaking time, particle size and stirring rate, were screened through Plackett-Burman design to determine the significant variables. Then, three parameters performed statistically significant, including liquid-solid ratio, ultrasound irradiation time and ultrasound irradiation power, were further optimized using Box-Behnken design to predict optimum extraction conditions. Satisfactory yield of samara oil (11.72±0.38%) and content of nervonic acid (5.28±0.18%) were achieved using the optimal conditions. 1% proportion of ethanol in extraction solvent, 120°C of drying temperature and 6.4% moisture were selected and applied for effective extraction. There were no distinct differences in the physicochemical properties of samara oil obtained by UCE and Soxhlet extraction, and the samara oil obtained by UCE exhibited better antioxidant activities. Therefore, UCE method has enormous potential for efficient extraction of edible oil with high quality from plant materials. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Seasonal changes in contents of phenolic compounds and sugar in Rhus, Euonymus and Acer leaves with special reference to anthocyanin formation in autumn

    International Nuclear Information System (INIS)

    Ishikura, Nariyuki

    1976-01-01

    The seasonal changes in the contents of sugar and phenolic compounds in the leaves of Rhus, Euonymus and two Acer species were examined in order to obtain information on the metabolic process inducing the autumn reddening. The incorporation of radioactivity of glucose-(U-14C) into anthocyanin was also examined. As a result of a preliminary test, the compositions of sugar and phenolic compounds were not altered by the drying treatment, therefore dried material was used. Dried leaves (ca. 2 g) were subject to the extraction with 80% methanol (3 ml, 3 hr) under refluxing. The extraction was repeated twice. Combined extracts (ca. 90 ml) were concentrated to ca. 20 ml at 35 deg C under reduced pressure. The concentrate was repeatedly washed with n-hexane and evaporated to remove the n-hexane. The resulting solution was made up to 30 ml with water, and used for the quantitative analysis. The solutions were fractionated in order to estimate total phenol and flavanol contents. Sugars were extracted from dry leaves (ca. 2 g) by boiling 70% ethanol (20 ml) for 3 hours. D-glucose-(U- 14 C)(280 mCi/mM) and phenylalanine-(U- 14 C)(422 mCi/mM) were fed to the leaves. It was found that antho-cyanin (mainly cyanidin 3-monoglucoside) was produced in the autumnal leaves of all plants examined, and that the red pigment was steadily accumulated in their leaves during the autumn. The sugar accumulated in autumnal Rhus leaves may be rapidly consumed by the formation of phenolic compounds. (Iwakiri, K.)

  11. Chemical and physical properties of two-year short-rotation deciduous species. [Olea sp. , Populus deltoides, Platanus sp. , Alnus glutinosa, Paulownia tomentosa, Robina pseudoacacia, Acer saccharinum

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C.S

    1982-01-01

    The following seven broadleaved species were tested: autumn olive (Olea sp.) eastern cottonwood (Populus deltoides), sycamore (Platanus species), black alder (Alnus glutinosa), royal paulownia (Paulownia tomentosa), black locust (Robina pseudoacacia) and silver maple (Acer saccharinum). The species and portions both significantly affected the chemical and the physical findings of the juvenile wood. The ages, which were tested in factorial combination with the species, also showed a significant effect on both the chemical and the physical properties of wood. All of the results indicated that both chemical and physical properties did vary with species, among the portions of the wood, and according to the ages of the wood. From the portion standpoint, the bark had higher gross heat content, sulphur content, ash content and lignin content, and it was also higher in all three kinds of extractives contents. The wood portion was found to be rich in holocellulose, alpha-cellulose and pentosan. In considering the chemical and physical properties of juvenile wood among the species, eastern cottonwood was found to have the highest value for ash content and all of the three kinds of extractives content. Paulownia had the highest value for sulphur content. Black locust had highest gross heat content, holocellulose and alpha-cellulose contents. Silver maple had highest lignin content. Results from this study showed that these seven juvenile hardwood species can produce high biomass yields of fibre and energy when grown under intensive care in central and southern Illinois sites. The best species of these seven tested woods seem to be black locust, which could also serve as a raw material for the pulp and paper industry, as well as for a fuel for energy generation. However, further economic and energy efficiency analyses are needed before judging the feasibility of these short-rotation juvenile hardwood species.

  12. Post polymerization cure shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S; Hearon, Michael Keith; Bearinger, Jane P

    2014-11-11

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  13. Volumetric polymerization shrinkage of contemporary composite resins

    Directory of Open Access Journals (Sweden)

    Halim Nagem Filho

    2007-10-01

    Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

  14. Stereospecific olefin polymerization with chiral metallocene catalysts

    OpenAIRE

    Brintzinger, Hans-Herbert; Fischer, David; Mülhaupt, Rolf; Rieger, Bernhard; Waymouth, Robert M.

    1995-01-01

    Current studies on novel, metallocenebased catalysts for the polymerization of α-olefins have far-reaching implications for the development of new materials as well as for the understanding of basic reaction mechanisms responsible for the growth of a polymer chain at a catalyst center and the control of its stereoregularity. In contrast to heterogeneous Ziegler–Natta catalysts, polymerization by a homogeneous, metallocene-based catalyst occurs principally at a single type of metal center with...

  15. Post polymerization cure shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Hearon, II, Michael Keith; Bearinger, Jane P.

    2017-01-10

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  16. Polymeric micelles for acyclovir drug delivery.

    Science.gov (United States)

    Sawdon, Alicia J; Peng, Ching-An

    2014-10-01

    Polymeric prodrug micelles for delivery of acyclovir (ACV) were synthesized. First, ACV was used directly to initiate ring-opening polymerization of ɛ-caprolactone to form ACV-polycaprolactone (ACV-PCL). Through conjugation of hydrophobic ACV-PCL with hydrophilic methoxy poly(ethylene glycol) (MPEG) or chitosan, polymeric micelles for drug delivery were formed. (1)H NMR, FTIR, and gel permeation chromatography were employed to show successful conjugation of MPEG or chitosan to hydrophobic ACV-PCL. Through dynamic light scattering, zeta potential analysis, transmission electron microscopy, and critical micelle concentration (CMC), the synthesized ACV-tagged polymeric micelles were characterized. It was found that the average size of the polymeric micelles was under 200nm and the CMCs of ACV-PCL-MPEG and ACV-PCL-chitosan were 2.0mgL(-1) and 6.6mgL(-1), respectively. The drug release kinetics of ACV was investigated and cytotoxicity assay demonstrates that ACV-tagged polymeric micelles were non-toxic. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. The tempered polymerization of human neuroserpin.

    Directory of Open Access Journals (Sweden)

    Rosina Noto

    Full Text Available Neuroserpin, a member of the serpin protein superfamily, is an inhibitor of proteolytic activity that is involved in pathologies such as ischemia, Alzheimer's disease, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB. The latter belongs to a class of conformational diseases, known as serpinopathies, which are related to the aberrant polymerization of serpin mutants. Neuroserpin is known to polymerize, even in its wild type form, under thermal stress. Here, we study the mechanism of neuroserpin polymerization over a wide range of temperatures by different techniques. Our experiments show how the onset of polymerization is dependent on the formation of an intermediate monomeric conformer, which then associates with a native monomer to yield a dimeric species. After the formation of small polymers, the aggregation proceeds via monomer addition as well as polymer-polymer association. No further secondary mechanism takes place up to very high temperatures, thus resulting in the formation of neuroserpin linear polymeric chains. Most interesting, the overall aggregation is tuned by the co-occurrence of monomer inactivation (i.e. the formation of latent neuroserpin and by a mechanism of fragmentation. The polymerization kinetics exhibit a unique modulation of the average mass and size of polymers, which might suggest synchronization among the different processes involved. Thus, fragmentation would control and temper the aggregation process, instead of enhancing it, as typically observed (e.g. for amyloid fibrillation.

  18. Characterization behavior of some polymeric composite ion exchangers

    International Nuclear Information System (INIS)

    El-Zahhar, A.A; Ahdel-Aziz, H.M.; Siyam, T.

    2005-01-01

    Polymeric composite resins were prepared by template polymerization process in aqueous solution. Thermogravimetric analysis (TGA), differential thermal analysis (DTA) and The X-ray diffraction patterns (XRD) were performed to evaluate the physico chemical properties of the different polymeric composite resins. The TGA and DTA clarify high thermal stability of prepared polymeric composite resins. XRD of prepared polymeric composite shows that there is crystalline structure of some resins while other are amorphous one

  19. Dormant Polymers and Their Role in Living and Controlled Polymerizations; Influence on Polymer Chemistry, Particularly on the Ring Opening Polymerization

    Directory of Open Access Journals (Sweden)

    Stanislaw Penczek

    2017-11-01

    Full Text Available Living polymerization discovered by Professor Szwarc is known well to all chemists. Some of the living polymerizations involve dormancy, a process in which there is an equilibrium (or at least exchange between two types of living polymers, namely active at the given moment and dormant at this moment and becoming active in the process of activation. These processes are at least equally important although less known. This mini review is devoted to these particular living polymerizations, mostly polymerizations by the Ring-Opening Polymerization mechanisms (ROP compared with some selected close to living vinyl polymerizations (the most spectacular is Atom Transfer Radical Polymerization (ATRP involving dormancy. Cationic polymerization of tetrahydrofuran was the first one, based on equilibrium between oxonium ions (active and covalent (esters dormant species, i.e., temporarily inactive, and is described in detail. The other systems discussed are polymerization of oxazolines and cyclic esters as well as controlled radical and cationic polymerizations of vinyl monomers.

  20. Genotoxic evaluation of polymeric nanoparticles

    Directory of Open Access Journals (Sweden)

    Tamara Iglesias Alonso

    2015-06-01

    Full Text Available An important strategy for optimizing the therapeutic efficacy of many conventional drugs is the development of polymeric nanoparticles (NPs, as it may expand their activities, reduce their toxicity, increase their bioactivity and improve biodistribution. The main objective of this study was to evaluate the genotoxicity of 8 different poly (anhydride NPs designed for the oral administration of therapeutic compounds by using the comet assay in combination with the enzyme formamidopypiridine DNA-glycosylase (FPG. Furthermore, the mitogen capacity of the NPs was evaluated by the proliferation assay. All NPs were tested at four concentrations (0, 0.5, 1 and 2 mg/mL in Caco-2 cells after 3 hours of treatment while selected NPs were also tested after 24 h. The comet assay was performed immediately after the treatment and cell proliferation was assessed by counting the treated cells after their incubation at 37 °C for 48h. Cells treated with 1 µM of the photosensitizer Ro 19-8022 plus 5 min of light, as well as cells treated with 100 µM H2O2 were included as positive controls in all the experiments. All NPs studied did not result in any increase in the frequency of strand breaks or alkali-labile sites in Caco-2 cells but they induced a slight concentration-dependent increase in net FPG sensitive sites (oxidized and/or alkylated bases. Furthermore, treated cells did not show changes in levels of proliferation in comparison with the negative control.

  1. Polymerization in emulsion microdroplet reactors

    Science.gov (United States)

    Carroll, Nick J.

    The goal of this research project is to utilize emulsion droplets as chemical reactors for execution of complex polymerization chemistries to develop unique and functional particle materials. Emulsions are dispersions of immiscible fluids where one fluid usually exists in the form of drops. Not surprisingly, if a liquid-to-solid chemical reaction proceeds to completion within these drops, the resultant solid particles will possess the shape and relative size distribution of the drops. The two immiscible liquid phases required for emulsion polymerization provide unique and complex chemical and physical environments suitable for the engineering of novel materials. The development of novel non-ionic fluorosurfactants allows fluorocarbon oils to be used as the continuous phase in a water-free emulsion. Such emulsions enable the encapsulation of almost any hydrocarbon compound in droplets that may be used as separate compartments for water-sensitive syntheses. Here, we exemplify the promise of this approach by suspension polymerization of polyurethanes (PU), in which the liquid precursor is emulsified into droplets that are then converted 1:1 into polymer particles. The stability of the droplets against coalescence upon removal of the continuous phase by evaporation confirms the formation of solid PU particles. These results prove that the water-free environment of fluorocarbon based emulsions enables high conversion. We produce monodisperse, cross-linked, and fluorescently labeled PU-latexes with controllable mesh size through microfluidic emulsification in a simple one-step process. A novel method for the fabrication of monodisperse mesoporous silica particles is presented. It is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to

  2. Survey and research on precision polymerization polymeric materials; Seimitsu jugo kobunshi zairyo ni kansuru chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    Survey and research on the precision control of primary structure of polymeric materials and the precision evaluation technology have been conducted to develop advanced polymeric materials. It is proposed that the three basic processes of polymer synthesis, i.e., addition, condensation, and biomimesis, in forming the precision polymerization skeleton are to be covered through a centralized joint research effort with participation of industry, academia, and the government institute and under the leadership of researchers from academic institutions as the team leaders. For the study of technology trends, international conferences held in UK, Germany, and Hawaii are introduced, and domestic meetings, i.e., Annual Polymer Congress and Polymer Conference, are summarized. In addition, Precision Polymerization Forum and International Workshop on Precision Polymerization were held. The basic studies include a quantum-chemical elucidation of the elementary process in polymerization reaction, time-resolved analysis of polymerization process and polymer properties, synthesis of polymers with controlled microstructures by coordination polymerization using metal complexes, synthesis of polymer with controlled microstructures by precision polycondensation, molecular recognition in catalyst-reaction site, and synthesis of imprinting polymers. 246 refs., 117 figs., 14 tabs.

  3. Effect of Small Reaction Locus in Free-Radical Polymerization: Conventional and Reversible-Deactivation Radical Polymerization

    Directory of Open Access Journals (Sweden)

    Hidetaka Tobita

    2016-04-01

    Full Text Available When the size of a polymerization locus is smaller than a few hundred nanometers, such as in miniemulsion polymerization, each locus may contain no more than one key-component molecule, and the concentration may become much larger than the corresponding bulk polymerization, leading to a significantly different rate of polymerization. By focusing attention on the component having the lowest concentration within the species involved in the polymerization rate expression, a simple formula can predict the particle diameter below which the polymerization rate changes significantly from the bulk polymerization. The key component in the conventional free-radical polymerization is the active radical and the polymerization rate becomes larger than the corresponding bulk polymerization when the particle size is smaller than the predicted diameter. The key component in reversible-addition-fragmentation chain-transfer (RAFT polymerization is the intermediate species, and it can be used to predict the particle diameter below which the polymerization rate starts to increase. On the other hand, the key component is the trapping agent in stable-radical-mediated polymerization (SRMP and atom-transfer radical polymerization (ATRP, and the polymerization rate decreases as the particle size becomes smaller than the predicted diameter.

  4. Catalytic Polymerization of Acrylonitrile by Khulays Bentonite

    Directory of Open Access Journals (Sweden)

    Matar M. Al-Esaimi

    2007-04-01

    Full Text Available The aqueous polymerization of acrylonitrile (AN catalyzed with exchanged Khulays bentonite . The influence of various polymerization parameters ( e.g., concentrations of Potassium Persulfate (K2S2O8 and monomer , various of organic solvents, and different temperature has been investigated. It was found that the rate of polymerization of AN was found to be dependent on monomer concentration, initiator and temperature. The activation energy of polymerization was calculated .Thermal properties of the polymer were studied by TGA and DSC techniques. © 2007 CREC UNDIP. All rights reserved.Received: 5 February 2007; Received in revised: 19 April 2007; Accepted: 7 May 2007[How to Cite: M. M. Al-Esaimi. (2007. Catalytic Polymerization of Acrylonitrile by Khulays Bentonite. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 32-36.  doi:10.9767/bcrec.2.1.4.6-10][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.1.4.6-10 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/4] 

  5. Obtención de un material vitrocerámico a partir de una escoria de acería mezclada con vidrio de desecho

    Directory of Open Access Journals (Sweden)

    Oziel Méndez Guerero, D.

    2011-06-01

    Full Text Available In this paper, the qualitative, quantitative and thermal characterization of a steel slag and glass cullet of high generation rate in northern Mexico were made in order to use these wastes as raw materials in the production of glassceramics. The particle size was controlled at sizes ≤ 75 micrometers and the major components of the slag were located in a phase equilibrium diagram for proposing a reaction temperature that leaded to the starting glass. Later, heat treatments were performed to obtain the glassceramics. The materials were characterized by powder X-ray diffraction (XRD, differential thermal analysis coupled with thermal gravimetric analysis (DTA-TGA, reflected light optical microscopy (RLOM and scanning electron microscopy (SEM. Subsequently, Vickers microhardness and chemical resistance tests were performed, which enabled us to propose an application of the glassceramics.

    En el presente trabajo se realizó la caracterización cualitativa, cuantitativa y térmica de una escoria de acería y un vidrio de desecho, ambos de elevada producción en la zona noreste de México, para utilizarlos como materia prima en la obtención de un material vitrocerámico. Se controló el tamaño de partícula a ≤ 75 micrómetros y se ubicaron los componentes mayoritarios de la escoria en un diagrama de equilibrio de fases, para proponer una temperatura de fusión que condujera al vidrio de partida. Posteriormente se realizaron los tratamientos térmicos para la obtención del vitrocerámico. Los materiales obtenidos se caracterizaron por difracción de rayos-X, método de polvos (DRX, análisis térmico diferencial-gravimétrico (ATD-TG, microscopía óptica de luz reflejada (MOLR y microscopía electrónica de barrido (MEB. Finalmente, se realizaron ensayos de microdureza Vickers y de resistencia al ataque químico que permitieron proponer una aplicación para el vitrocerámico.

  6. Fast-growing Acer rubrum differs from slow-growing Quercus alba in leaf, xylem and hydraulic trait coordination responses to simulated acid rain.

    Science.gov (United States)

    Medeiros, Juliana S; Tomeo, Nicholas J; Hewins, Charlotte R; Rosenthal, David M

    2016-08-01

    We investigated the effects of historic soil chemistry changes associated with acid rain, i.e., reduced soil pH and a shift from nitrogen (N)- to phosphorus (P)-limitation, on the coordination of leaf water demand and xylem hydraulic supply traits in two co-occurring temperate tree species differing in growth rate. Using a full-factorial design (N × P × pH), we measured leaf nutrient content, water relations, leaf-level and canopy-level gas exchange, total biomass and allocation, as well as stem xylem anatomy and hydraulic function for greenhouse-grown saplings of fast-growing Acer rubrum (L.) and slow-growing Quercus alba (L.). We used principle component analysis to characterize trait coordination. We found that N-limitation, but not P-limitation, had a significant impact on plant water relations and hydraulic coordination of both species. Fast-growing A. rubrum made hydraulic adjustments in response to N-limitation, but trait coordination was variable within treatments and did not fully compensate for changing allocation across N-availability. For slow-growing Q. alba, N-limitation engendered more strict coordination of leaf and xylem traits, resulting in similar leaf water content and hydraulic function across all treatments. Finally, low pH reduced the propensity of both species to adjust leaf water relations and xylem anatomical traits in response to nutrient manipulations. Our data suggest that a shift from N- to P-limitation has had a negative impact on the water relations and hydraulic function of A. rubrum to a greater extent than for Q. alba We suggest that current expansion of A. rubrum populations could be tempered by acidic N-deposition, which may restrict it to more mesic microsites. The disruption of hydraulic acclimation and coordination at low pH is emphasized as an interesting area of future study. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Methylenelactide: vinyl polymerization and spatial reactivity effects

    Directory of Open Access Journals (Sweden)

    Judita Britner

    2016-11-01

    Full Text Available The first detailed study on free-radical polymerization, copolymerization and controlled radical polymerization of the cyclic push–pull-type monomer methylenelactide in comparison to the non-cyclic monomer α-acetoxyacrylate is described. The experimental results revealed that methylenelactide undergoes a self-initiated polymerization. The copolymerization parameters of methylenelactide and styrene as well as methyl methacrylate were determined. To predict the copolymerization behavior with other classes of monomers, Q and e values were calculated. Further, reversible addition fragmentation chain transfer (RAFT-controlled homopolymerization of methylenelactide and copolymerization with N,N-dimethylacrylamide was performed at 70 °C in 1,4-dioxane using AIBN as initiator and 2-(((ethylthiocarbonothioylthio-2-methylpropanoic acid as a transfer agent.

  8. Cross-linking of polymeric materials

    International Nuclear Information System (INIS)

    Bloom, L.I.; Du Plessis, T.A.; Meij, G.O.

    1991-01-01

    The invention provides a method of producing a cured polymeric artifact from a polymeric thermoplastic starting material, the material of the artifact having reduced thermoplasticity relative to the starting material and exhibiting an enhanced degree of cross-linking relative to the starting material. The method includes subjecting a polymeric thermoplastic starting material, which is capable of being cross-linked by irradiation, to sufficient irradiation partially to cross-linked the starting material to produce a thermoplastic partially cross-linked intermediate material. The thermoplasticity of the intermediate material is then reduced by heating it to raise its melting point. The invention also provides a method of making a partially cross-linked feedstocks and a master batch for use in making such artifacts

  9. Development of radioisotope labeled polymeric carriers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Jin; Jeong, Jea Min; Hwang, Hyun Jeong [Ewha Womans University, Seoul (Korea)

    2000-04-01

    This research was performed with the aim of developing polymeric radioisotope or drug carriers for obtaining efficient diagnostic therapeutic efficacy. As polymers, polyethylene oxides, polylactides, polycaprolactone were chosen to prepare the devices including micelle system, microemulsion, nanospheres. In addition, anticancer drug loaded polylactide microparticulates were fabricated as a regional chemotherapeutics for the treatment of cancer. Technetium or radioactive iodine was labeled to the polymeric carriers via ligands such as DTPA and HPP, respectively. Labeling efficiency was above 90% and stable enough up to 24 hours. Moreover, injected polymer carriers demonstrated higher blood maintenance and bone uptake than Tin colloid, a control. These results suggested that radioisotope carrying polymeric particulate are promising tools for diagnosing blood vessels or bones. Besides, anticancer drug loaded particulates demonstrated appropriate maintenance of therapeutic concentration and localization. Therefore it was proposed that this therapeutic system may be potential as a cancer therapy modality. 20 refs., 24 figs.,5 tabs. (Author)

  10. Laser microstructuring for fabricating superhydrophobic polymeric surfaces

    Science.gov (United States)

    Cardoso, M. R.; Tribuzi, V.; Balogh, D. T.; Misoguti, L.; Mendonça, C. R.

    2011-02-01

    In this paper we show the fabrication of hydrophobic polymeric surfaces through laser microstructuring. By using 70-ps pulses from a Q-switched and mode-locked Nd:YAG laser at 532 nm, we were able to produce grooves with different width and separation, resulting in square-shaped pillar patterns. We investigate the dependence of the morphology on the surface static contact angle for water, showing that it is in agreement with the Cassie-Baxter model. We demonstrate the fabrication of a superhydrophobic polymeric surface, presenting a water contact angle of 157°. The surface structuring method presented here seems to be an interesting option to control the wetting properties of polymeric surfaces.

  11. Fabrication of triazinedithiol functional polymeric nanofilm by potentiostatic polymerization on aluminum surface

    International Nuclear Information System (INIS)

    Wang Fang; Wang Yabin; Li Yanni; Wang Qian

    2011-01-01

    The functional polymeric nanofilm of 6-(N-allyl-1,1,2,2-tetrahydroperfluorodecyl)amino-1,3,5-triazine-2, 4-dithiol monosodium (AF17N) was prepared on pure aluminum surface by potentiostatic polymerization at different potentials. The thickness and weight of polymeric nanofilm increased proportionally to electro-polymerization potential following linear equation. The chemical structure of nanofilm was characterized by Fourier transform-infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Adsorption peaks in FT-IR and C1s, N1s, S2p, F1s and Al2p peaks in XPS spectra indicated that the polymeric nanofilm was poly(6-(N-allyl-1,1,2,2-tetrahydroperfluorodecyl)amino-1,3,5-triazine-2, 4-disulfide) (PAF17). The morphologies of polymeric nanofilm were also observed by atomic force microscopy (AFM). All the results showed that the optimal electro-polymerization potential and time were 8 V and 20 s, respectively. Uniform and compact nanofilm of PAF17 could be obtained under these conditions. It is expected that this technique will be applied in the preparation of lubricating, dielectric and hydrophobic surface on aluminum substrate.

  12. Fluorocarbon-hydrocarbon incompatibility in micellar polymerizations.

    Science.gov (United States)

    Rogers, Sarah E; Eastoe, Julian; Hudson, Laura; Gold, Sarah; Heenan, Richard K; Grillo, Isabelle

    2009-02-15

    A new approach to micellar polymerization is described. It is well known that hydrocarbons and fluorocarbons exhibit local phase segregation (demixing) owing to mutual antipathy; here this effect is employed in monomer swollen micelles with appropriate combinations of hydrocarbon and fluorocarbon monomers and surfactants. A matrix of these hydro- and fluorocarbon components has been investigated to delineate the effects of H-F antipathy on the outcomes of polymerization reactions to generate nanolatices of different size (and possibly morphology). Phase diagrams, (1)H NMR and small-angle neutron (SANS) data have been generated to characterize the systems, indicating new routes to influence nanolatex formation.

  13. MODERN TECHNOLOGY OF ANIONIC POLYMERIZATION MONOMERS

    Directory of Open Access Journals (Sweden)

    A. V. Tkachev

    2013-01-01

    Full Text Available The preconditions of use in the manufacture of automobile tyres of vulcanizates-based mortar butadienestyrene rubber with a high content of 1.2 links butadiene and statistical distribution of styrene are formulated. Set out scientific researches in the field of anionic co-polymerization of diene and vinyl aromatic monomers. Formulation of catalytic systems applied in processes of anionic copolymerization of monomers are given. The reasons of formation of gel in the process of anionic polymerization of monomers and terms of their elimination are considered.

  14. Functional Materials from Polymeric Ionic Liquids

    Science.gov (United States)

    Segalman, Rachel; Sanoja, Gabriel; Michenfelder-Schauser, Nicole; Mitragotri, Samir; Seshadri, Ram

    Ionic liquids (IL's) have been suggested for applications as diverse as solubilizing cellulose, antimicrobial treatments, and electrolytes in batteries due to their molten salt properties. A polymeric cation (such as imidazolium) is an excellent host for any associated anion. As a result, polymerized ionic liquids are not just solid counterparts to IL's, but are shown to be vectors for the inclusion of a wide variety of functionalities ranging from multi-valent ions to magnetic anions. Moreover, PIL block copolymers allow orthogonal control over mechanical and morphological properties, ultimately leading to a conceptual framework for processable, tunable, multifunctional materials.

  15. Mechanism and kinetics of addition polymerizations

    CERN Document Server

    Kucera, M

    1991-01-01

    This volume presents an up-to-date survey of knowledge concerning addition type polymerizations. It contains nine chapters, each of which covers a particular basic term. Whenever necessary, the phenomena are discussed from the viewpoint of both stationary and non-stationary state of radical, ionic (i.e. anionic and cationic) and coordination polymerization. Special attention has been paid to the propagation process. It provides not only a general overview but also information on important special cases (theoretical conditions of propagation, influence of external factors, controlled propagatio

  16. Polymeric matrix materials for infrared metamaterials

    Science.gov (United States)

    Dirk, Shawn M; Rasberry, Roger D; Rahimian, Kamyar

    2014-04-22

    A polymeric matrix material exhibits low loss at optical frequencies and facilitates the fabrication of all-dielectric metamaterials. The low-loss polymeric matrix material can be synthesized by providing an unsaturated polymer, comprising double or triple bonds; partially hydrogenating the unsaturated polymer; depositing a film of the partially hydrogenated polymer and a crosslinker on a substrate; and photopatterning the film by exposing the film to ultraviolet light through a patterning mask, thereby cross-linking at least some of the remaining unsaturated groups of the partially hydrogenated polymer in the exposed portions.

  17. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Hassager, Ole

    1999-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane. The polymeric materialis described by an arbitrary combination of a viscoelastic and a purely viscous component to the stress. Some viscoelastic materials described by a Mooney......-Rivlin model show a monotone increasingpressure during inflation of a spherical membrane. These materials develop a homogeneous membrane thickness in agreement with the Considere-Pearson condition. Molecularly based models such as the neo-Hookean, Doi-Edwards or Tom-Pom model show a pressure maximum when...... inflated. Membranesdescribed by these models develop a local thinning of the membrane which may lead to bursting in finite time....

  18. Polymerization Initiated at the Sidewalls of Carbon Nanotubes

    Science.gov (United States)

    Tour, James M.; Hudson, Jared L.

    2011-01-01

    A process has been developed for growing polymer chains via anionic, cationic, or radical polymerization from the side walls of functionalized carbon nanotubes, which will facilitate greater dispersion in polymer matrices, and will greatly enhance reinforcement ability in polymeric material.

  19. Polymerization of epoxy resins studied by positron annihilation

    International Nuclear Information System (INIS)

    Suzuki, T.; Hayashi, T.; Ito, Y.

    1999-01-01

    The polymerization process of epoxy resins (bisphenol-A dicyanate) was studied using positron-annihilation spectroscopy. The polymerization from monomer to polymer through a polymerization reaction was followed by positron-annihilation lifetime spectroscopy measurements. Resins kept at curing temperatures (120, 150 and 200 o C) changed form from of powder to a solid through a liquid. The size of the intermolecular spaces of the solid samples increased along with the progress of polymerization. (author)

  20. Interaction of acetamiprid with extracellular polymeric substances ...

    African Journals Online (AJOL)

    Extracellular polymeric substances (EPS) are important components of activated sludge and it plays an important role in removing pollutants. The interaction between EPS and organic pollutants is still little known. In the present study, the interaction of soluble/bound EPS with acetamiprid, a neonicotinoid insecticide, was ...

  1. Vinyl acetate polymerization by ionizing radiation

    International Nuclear Information System (INIS)

    Mesquita, Andrea Cercan

    2002-01-01

    The aim of this work is the synthesis and characterization of the poly(vinyl acetate) using the ionizing radiation. Six polymerizations of vinyl acetate were carried out using three techniques of polymerization: in bulk, emulsion and solution. In the technique of solution polymerization were used two solvents, the alcohol ethyl and the methylethylketone, in two proportions 1:0.5 and 1:1 related to the monomer. The solutions were irradiated with gamma rays from a 60 Co source, with dose rate between 5.25 kGy/h and 6.26 kGy/h. The polymers obtained were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The glass transition temperature (Tg) was investigated by Differential Scanning Calorimeter (DSC). The molecular weight was analyzed by the technique of Gel Permeation Chromatography (GPC). Tests of density, hardness and Vicat softening temperature were carried out. The infrared spectroscopy and others results confirmed that the polymers obtained by polymerization of vinyl acetate in bulk, emulsion and solution, using ionizing radiation, really correspond at poly(vinyl acetate). (author)

  2. Olefin polymerization over supported chromium oxide catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    1999-01-01

    Cr/SiO2 or Phillips-type catalysts are nowadays responsible for a large fraction of all polyethylene (HDPE and LLDPE) worldwide produced. In this review, several key-properties of Cr/SiO2 catalysts will be discussed in relation to their polymerization characteristics. It will be shown how the

  3. Gamma Radiation-Induced Template Polymerization Technique

    International Nuclear Information System (INIS)

    Siyam, T.

    2005-01-01

    Gamma radiation induced copolymerization of acrylamide sodiumacrylate (AM-AANa) in the presence and absence of the polymer additive was studied at low monomer concentration(1.4M/l). The results showed that the exponents of the dose rate for the polymerization rate was found to be 1.3 and 1.4 in the absence and in the presence of the polymer additive respectively. The molecular weight of the formed polymer increased by addition of the polymer to the system. In the presence of the polymer the comonomers polymerize on the added polymer. In the absence of the added polymer the comonomers polymerize according to the copolymerization process at the initial stage of the copolymerization. While at high conversion the residual comonomers polymerize on the formed macromolecular chains of the produced polymer. These studies showed that the copolymerization in the presence of added polymer is completely template copolymerization while in the absence of the polymer the copolymerization process is only template process with a high conversion

  4. Nylon 6 polymerization in the solid state

    NARCIS (Netherlands)

    Gaymans, R.J.; Amirtharaj, John; Kamp, Henk

    1982-01-01

    The postcondensation of nylon 6 in the solid state was studied. The reactions were carried out on fine powder in a fluidized bed reactor in a stream of dry nitrogen in the temperature range 110-205°C and during 1-24 h. The solid-state polymerization (SSP) did not follow melt kinetics, but was found

  5. Polymeric components for telecom and datacom

    NARCIS (Netherlands)

    Diemeer, Mart; Dekker, R.; Hilderink, L.T.H.; Leinse, Arne; Balakrishnan, M.; Faccini, M.; Driessen, A.; Lambeck, Paul; Gorecki, Christophe; Pustelny, Tadeusz

    2005-01-01

    Polymeric optical waveguide components offer attractive properties for applications in optical telecom and datacom systems. These are high speed for electro-optic modulators, low power dissipation for thermo-optic (digital) switches and low-cost for all active and passive components. We report on

  6. Polymeric microsieves produced by phase separation micromolding

    NARCIS (Netherlands)

    Girones nogue, Miriam; Akbarsyah, I.J.; Nijdam, W.; Nijdam, W.; van Rijn, C.J.M.; Jansen, Henricus V.; Lammertink, Rob G.H.; Wessling, Matthias

    2006-01-01

    The fabrication of polymeric microsieves with tunable properties (pore size, shape or porosity) is described in this work. Perfectly structured freestanding membranes and accurate replicas of polyethersulfone (PES), copolymers of polyethersulfone and polyethylene oxide (PES–PEO), and blends of PES

  7. Effective thermal conductivity of condensed polymeric nanofluids ...

    Indian Academy of Sciences (India)

    Thermal properties of polymeric nanosolids, obtained by condensing the corresponding nanofluids, are investigated using photothermal techniques. The heat transport properties of two sets of polyvinyl alcohol (PVA) based nanosolids, TiO2/PVA and Cu/PVA, prepared by condensing the respective nanofluids, which are ...

  8. Hyaluronan polymeric micelles for topical drug delivery

    Czech Academy of Sciences Publication Activity Database

    Šmejkalová, D.; Muthný, T.; Nešporová, K.; Hermannová, M.; Achbergerová, E.; Huerta-Angelesa, G.; Marek Svoboda, M.; Čepa, M.; Machalová, V.; Luptáková, Dominika; Velebný, V.

    2017-01-01

    Roč. 156, JAN 20 (2017), s. 86-96 ISSN 0144-8617 Institutional support: RVO:61388971 Keywords : Skin penetration * Polymeric micelle * Hyaluronan Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 4.811, year: 2016

  9. Polymeric Cantilever Arrays for Biosensing Applications

    DEFF Research Database (Denmark)

    Calleja, M.; Tamayo, J.; Johansson, Alicia

    2003-01-01

    We report the fabrication of arrays of polymeric cantilevers for biochemistry applications. The cantilevers are fabricated in the polymer SU-8. The use of a polymer as the component material for the cantilevers provides the sensors with very high sensitivity due to convenient mechanical material...

  10. Inflation and Failure of Polymeric Membranes

    DEFF Research Database (Denmark)

    Hassager, Ole; Neergaard, Jesper

    2000-01-01

    We consider the inflation of an axisymmetric polymeric membrane.Some membranes composed of viscoelastic materialsdescribed by a Mooney-Rivlin model show a monotone increasingpressure during inflation. These materialsdevelop a homogeneous membrane thickness in agreement with the Considere...... is found to stabilize the inflated polymer membrane....

  11. Proteins and Peptides in Biomimetic Polymeric Membranes

    DEFF Research Database (Denmark)

    Perez, Alfredo Gonzalez

    2013-01-01

    This chapter discusses recent advances and the main advantages of block copolymers for functional membrane protein reconstitution in biomimetic polymeric membranes. A rational approach to the reconstitution of membrane proteins in a functional form can be addressed by a more holistic view by using...

  12. On viscoelastic instability in polymeric filaments

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Hassager, Ole

    1999-01-01

    The 3D Lagrangian Integral Method is used to simulate the effects of surface tension on the viscoelastic end-plate instability, occuring in the rapid extension of some polymeric filaments between parallel plates. It is shovn that the surface tension delays the onset of the instability. Furthermore...

  13. Separation of bacteria with imprinted polymeric films

    NARCIS (Netherlands)

    Schirhagl, Romana; Hall, Eric W; Fuereder, Ingo; Zare, Richard N

    2012-01-01

    Separation of compounds out of complex mixtures is a key issue that has been solved for small molecules by chromatography. However, general methods for the separation of large bio-particles, such as cells, are still challenging. We demonstrate integration of imprinted polymeric films (IPF) into a

  14. Transport through track etched polymeric blend membrane

    Indian Academy of Sciences (India)

    Unknown

    mers having a common ring structure (bisphenol-A) in their repeating unit. Polysulphone has an additional ring structure and –SO2 group in its repeating unit. The blend of these polymeric materials may form some new bonds. The permeability of polymers depends on the operating conditions such as temperature, pressure ...

  15. Characteristic emission in glutaraldehyde polymerized hemoglobin

    International Nuclear Information System (INIS)

    Ma Li; Wang Xiaojun

    2011-01-01

    Hemoglobin with different modifications has been investigated using spectroscopic techniques. A new emission at around 371 nm has been observed under excitation of 305 nm from glutaraldehyde polymerized human hemoglobin. Intensity and peak position of the emission are dependent on both oxidation state and ligand environment and the emission has been identified from the hemoglobin oligomer.

  16. TRANSITION METAL CATALYSIS IN CONTROLLED RADICAL POLYMERIZATION: ATOM TRANSFER RADICAL POLYMERIZATION. (R826735)

    Science.gov (United States)

    Novel and diversified macromolecular structures, which include polymers with designed topologies (top), compostions (middle), and functionalities (bottom), can be prepared by atom transfer radical polymerization processes. These polymers can be synthesized from a large variety of...

  17. Development of Nanocomposite Reinforced Polymeric Materials to be Used for Racks for Retorting Polymeric Trays

    National Research Council Canada - National Science Library

    Sue, Hung-Jue

    2003-01-01

    .... This report summarizes activity under Short Term Project 2007. The ultimate goal of this project was to develop a material to improve the performance and cost effectiveness of polymeric trays used for retorting Polytray rations...

  18. Carboxyl-Functionalized Polymeric Microspheres Prepared by One-Stage Photoinitiated RAFT Dispersion Polymerization

    Directory of Open Access Journals (Sweden)

    Jianbo Tan

    2017-12-01

    Full Text Available Herein, we report a photoinitiated reversible addition-fragmentation chain transfer (RAFT dispersion copolymerization of methyl methacrylate (MMA and methyl methacrylic (MAA for the preparation of highly monodisperse carboxyl-functionalized polymeric microspheres. High rates of polymerization were observed, with more than 90% particle yields being achieved within 3 h of UV irradiation. Effects of reaction parameters (e.g., MAA concentration, RAFT agent concentration, photoinitiator concentration, and solvent composition were studied in detail, and highly monodisperse polymeric microspheres were obtained in most cases. Finally, silver (Ag composite microspheres were prepared by in situ reduction of AgNO3 using the carboxyl-functionalized polymeric microspheres as the template. The obtained Ag composite microspheres were able to catalyze the reduction of methylene blue (MB with NaBH4 as a reductant.

  19. preparation of spherical polymeric particles from tanzanian cashew

    African Journals Online (AJOL)

    on suspension polymerization of the same, to produce surface reactive materials. In this work, suspension polymerization of CNSL and its distillate product cardanol to produce spherical polymeric particles (SPP) and surface characterization of the latter is reported. EXPERIMENTAL. Materials. Technical CNSL was supplied ...

  20. TEMPERATURE EFFECTS ON THE KINETICS OF PHOTOINITIATED POLYMERIZATION OF DIMETHACRYLATES

    NARCIS (Netherlands)

    BROER, DJ; MOL, GN; CHALLA, G

    1991-01-01

    The photoinitiated polymerization of three bisphenol-A-based dimethacrylates is studied. The polymerization rate of the dimethacrylate increases with temperature up to 160-degrees-C. Above this temperature depropagation starts to dominate the polymerization and the rate approaches zero above

  1. FtsZ Polymerization Assays : Simple Protocols and Considerations

    NARCIS (Netherlands)

    Król, Ewa; Scheffers, Dirk-Jan

    2013-01-01

    During bacterial cell division, the essential protein FtsZ assembles in the middle of the cell to form the so-called Z-ring. FtsZ polymerizes into long filaments in the presence of GTP in vitro, and polymerization is regulated by several accessory proteins. FtsZ polymerization has been extensively

  2. 21 CFR 870.3650 - Pacemaker polymeric mesh bag.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

  3. Threshold Particle Diameters in Miniemulsion Reversible-Deactivation Radical Polymerization

    Directory of Open Access Journals (Sweden)

    Hidetaka Tobita

    2011-11-01

    Full Text Available Various types of controlled/living radical polymerizations, or using the IUPAC recommended term, reversible-deactivation radical polymerization (RDRP, conducted inside nano-sized reaction loci are considered in a unified manner, based on the polymerization rate expression, Rp = kp[M]K[Interm]/[Trap]. Unique miniemulsion polymerization kinetics of RDRP are elucidated on the basis of the following two factors: (1 A high single molecule concentration in a nano-sized particle; and (2 a significant statistical concentration variation among particles. The characteristic particle diameters below which the polymerization rate start to deviate significantly (1 from the corresponding bulk polymerization, and (2 from the estimate using the average concentrations, can be estimated by using simple equations. For stable-radical-mediated polymerization (SRMP and atom-transfer radical polymerization (ATRP, an acceleration window is predicted for the particle diameter range, . For reversible-addition-fragmentation chain-transfer polymerization (RAFT, degenerative-transfer radical polymerization (DTRP and also for the conventional nonliving radical polymerization, a significant rate increase occurs for . On the other hand, for  the polymerization rate is suppressed because of a large statistical variation of monomer concentration among particles.

  4. Free heme and sickle hemoglobin polymerization

    Science.gov (United States)

    Uzunova, Veselina V.

    This work investigates further the mechanism of one of the most interesting of the protein self-assembly systems---the polymerization of sickle hemoglobin and the role of free heme in it. Polymerization of sickle hemoglobin is the primary event in the pathology of a chronic hemolytic condition called sickle cell anemia with complex pathogenesis, unexplained variability and symptomatic treatment. Auto-oxidation develops in hemoglobin solutions exposed to room temperature and causes release of ferriheme. The composition of such solutions is investigated by mass spectrometry. Heme dimers whose amount corresponds to the initial amounts of heme released from the protein are followed. Differences in the dimer peak height are established for hemoglobin variants A, S and C and depending on the exposure duration. The effects of free heme on polymerization kinetics are studied. Growth rates and two characteristic parameters of nucleation are measured for stored Hb S. After dialysis of polymerizing solutions, no spherulites are detected at moderately high supersaturation and prolonged exposure times. The addition of 0.16-0.26 mM amounts of heme to dialyzed solutions leads to restoration of polymerization. The measured kinetic parameters have higher values compared to the ones before dialysis. The amount of heme in non-dialyzed aged solution is characterized using spectrophotometry. Three methods are used: difference in absorbance of dialyzed and non-dialyzed solutions, characteristic absorbance of heme-albumin complex and absorbance of non-dialyzed solutions with added potassium cyanide. The various approaches suggest the presence of 0.12 to 0.18 mM of free ferriheme in such solutions. Open questions are whether the same amounts of free heme are present in vivo and whether the same mechanism operates intracellulary. If the answer to those questions is positive, then removal of free heme from erythrocytes can influence their readiness to sickle.

  5. NATO Advanced Study Institute on Ring-opening Metathesis Polymerization of Olefins and Polymerization of Alkynes

    CERN Document Server

    1998-01-01

    The first NATO Advanced Study Institute on Olefin Metathesis and Polymerization Catalysts was held on September 10-22, 1989 in Akcay, Turkey. Based on the fundamental research of RRSchrock, RGrubbs and K.B.Wagener in the field of ring opening metathesis polymerization (ROMP), acyclic diene metathesis (ADMET) and alkyne polymerization, these areas gained growing interest within the last years. Therefore the second NATO-ASI held on metathesis reactions was on Ring Opening Metathesis Po­ lymerization of Olefins and Polymerization of Alkynes on September 3-16, 1995 in Akcay, Turkey. The course joined inorganic, organic and polymer chemists to exchange their knowledge in this field. This volume contains the main and short lectures held in Akcay. To include ADMET reactions better into the title of this volume we changed it into: Metathesis Polymerization of Olefins and Alkyne Polymerization. This volume is addressed to research scientists, but also to those who start to work in the area of olefin metathesis and al...

  6. Preparation of Superhydrophobic Polymeric Film on Aluminum Plates by Electrochemical Polymerization

    Directory of Open Access Journals (Sweden)

    Juan Xu

    2009-11-01

    Full Text Available 6-(N-Allyl-1,1,2,2-tetrahydroperfluorododecylamino-1,3,5-triazine-2,4-dithiol monosodium (ATP was used to prepare polymeric thin films on pure aluminum plates to achieve a superhydrophobic surface. The electrochemical polymerization process of ATP on aluminum plates in NaNO2 aqueous solution and the formation of poly(6-(N-allyl-1,1,2,2-tetrahydroperfluorododecylamino-1,3,5-triazine-2,4-dithiol (PATP thin film were studied by means of optical ellipsometry and film weight. The chemical structure of the polymeric film is investigated using FT-IR spectra and X-ray photoelectron spectroscopy (XPS. Contact angle goniometry was applied to measure the contact angles with distilled water drops at ambient temperature. The experimental results indicate that the polymeric film formed on pure aluminum plates exhibits superhydrophobic properties with a distilled water contact angle of 153°. The electrochemical polymerization process is time-saving, inexpensive, environmentally friendly and fairly convenient to carry out. It is expected that this technique will advance the production of superhydrophobic materials with new applications on a large scale. Moreover, this kind of polymeric thin film can be used as a dielectric material due to its insulating features.

  7. Signal amplification strategies for DNA and protein detection based on polymeric nanocomposites and polymerization: A review

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shaohong; Yuan, Liang; Hua, Xin; Xu, Lingling; Liu, Songqin, E-mail: liusq@seu.edu.cn

    2015-06-02

    Highlights: • We review the innovative advances in polymer-based signal amplification. • Conceptual connectivity between different amplified methodologies is illustrated. • Examples explain the mechanisms of polymers/polymerizations-based amplification. • Several elegant applications are summarized that illustrate underlying concept. - Abstract: Demand is increasing for ultrasensitive bioassays for disease diagnosis, environmental monitoring and other research areas. This requires novel signal amplification strategies to maximize the signal output. In this review, we focus on a series of significant signal amplification strategies based on polymeric nanocomposites and polymerization. Some common polymers are used as carriers to increase the local concentration of signal probes and/or biomolecules on their surfaces or in their interiors. Some polymers with special fluorescence and optical properties can efficiently transfer the excitation energy from a single site to the whole polymer backbone. This results in superior fluorescence signal amplification due to the resulting collective effort (integration of signal). Recent polymerization-based signal amplification strategies that employ atom transfer radical polymerization (ATRP) and photo-initiated polymerization are also summarized. Several distinctive applications of polymers in ultrasensitive bioanalysis are highlighted.

  8. Antibiotic polymeric nanoparticles for biofilm-associated infection therapy.

    Science.gov (United States)

    Cheow, Wean Sin; Hadinoto, Kunn

    2014-01-01

    Polymeric nanoparticles are highly attractive as drug delivery vehicles due to their high structural integrity, stability during storage, ease of preparation and functionalization, and controlled release capability. Similarly, lipid-polymer hybrid nanoparticles, which retain the benefits of polymeric nanoparticles plus the enhanced biocompatibility and prolonged circulation time owed to the lipids, have recently emerged as a superior alternative to polymeric nanoparticles. Drug nanoparticle complex prepared by electrostatic interaction of oppositely charged drug and polyelectrolytes represents another type of polymeric nanoparticle. This chapter details the preparation, characterization, and antibiofilm efficacy testing of antibiotic-loaded polymeric and hybrid nanoparticles and antibiotic nanoparticle complex.

  9. Complex Macromolecular Architectures by Living Cationic Polymerization

    KAUST Repository

    Alghamdi, Reem D.

    2015-05-01

    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  10. Radiation polymerization of tetrafluoroethylene in gas-phase

    International Nuclear Information System (INIS)

    Enslin, S.E.; Schnautz, N.G.; Van der Ende, E.

    1986-01-01

    The radiation polymerization of tetrafluoroethylene in gas-phase was studied over a temperature range of -80 to 200 degrees Celsius and an irradiation dose-rate of 0,30 to 10,8 kGy h sup(-1). The rate of polymerization was observed during the course of the polymerization process, to be a zero-order function of monomer pressure. However, the rate of polymerization was profoundly influenced by the initial monomer pressure, in this case exhibiting a 4,6-order dependence. The rate of polymerization was also observed to exhibit a 0,36-order dependence on radiation intensity. Both the rate of polymerization and the molecular mass of the product, polytetrafluoroethylene, reached maximum values over the temperature range of 90 to 150 degrees Celsius. The activation energy for the polymerization process was determined to be 8,7 kJ mol sup(-1) over the temperature range of -80 to 90 degrees Celsius

  11. Wettability of nonwoven polymeric nanofiber mats

    Science.gov (United States)

    Munoz, Edgar

    The wettability of heterogeneous materials has been attracting special interest by academia and industrial sector given the need to development self-cleaning Nonwoven nanofiber mats have demonstrated potential given its hydrophobicity granted by the ultimate structure of the system, small fiber diameter and small pores giving rise to effects such as the Cassie-Baxter. This thesis analyzed the wettability of a wide range of polymeric systems. Nanofiber mats were manufactured using the ForcespinningRTM technology. Samples were prepared at different polymeric concentrations and rotational speeds to alter fiber size; density of the mat was also altered to evaluate the effect of porosity on the wettability. Scanning Electron Microscopy (SEM) was used to characterize the mats and contact angle studies were conducted to better understand wettability of the developed surfaces.

  12. Biomimetic polymeric membranes for water treatment

    DEFF Research Database (Denmark)

    Habel, Joachim Erich Otto

    This project is about the interplay of the three major components of aquaporin based biomimetic polymeric membranes (ABPMs): Aquaporins (AQPs), amphiphilic block copolymers, serving as a vesicular matrix for the hydrophobic AQP exterior (proteopolymersomes) and a polymeric membrane as embedment...... for the proteopolymersomes and mechanical support. To reach maximal functionality of ABPMs, the interplay of each component needs to be optimized. The optimization of AQPs and amphiphilic block copolymers was investigated by mixing bacterial Aquaporin Z (AqpZ) with polybutadiene polyethylene oxide (PB-PEO) diblock...... analysis turned out to give reliable information on polymersome size like known techniques such as Cryo-TEM. Cryo-TEM gave as well reliable information about lamellarity, SAXS/SANS about bilayer thickness. SEM, FTIR and microfluidic experiments on the interaction between all three components of ABPMs...

  13. Plasma polymerization for high Tc oxide superconductors

    Science.gov (United States)

    Morohashi, Shin'ichi; Tamura, Hirotaka; Yoshida, Akira; Hasuo, Shinya

    1988-05-01

    Plasma polymerization using CHF3 gas, which prevents the degradation of high Tc oxide superconductors due to moisture and annealing, was developed. The resistive transitions of Y1Ba2Cu3Ox thin films, coated by plasma polymerization, did not change before and after soaking in 20 °C water for 60 min. In addition, the critical temperature of those films was unchanged after annealing at 200 °C for 30 min in air, and then soaking in 90 °C water for 10 min. We confirmed that the polymer film grown by this method was dense, and the Y1Ba2Cu3Ox film reacted with the fluorine at the interface using x-ray photoelectron spectroscopy.

  14. Polymeric multilayer capsules in drug delivery.

    Science.gov (United States)

    De Cock, Liesbeth J; De Koker, Stefaan; De Geest, Bruno G; Grooten, Johan; Vervaet, Chris; Remon, Jean Paul; Sukhorukov, Gleb B; Antipina, Maria N

    2010-09-17

    Recent advances in medicine and biotechnology have prompted the need to develop nanoengineered delivery systems that can encapsulate a wide variety of novel therapeutics such as proteins, chemotherapeutics, and nucleic acids. Moreover, these delivery systems should be "intelligent", such that they can deliver their payload at a well-defined time, place, or after a specific stimulus. Polymeric multilayer capsules, made by layer-by-layer (LbL) coating of a sacrificial template followed by dissolution of the template, allow the design of microcapsules in aqueous conditions by using simple building blocks and assembly procedures, and provide a previously unmet control over the functionality of the microcapsules. Polymeric multilayer capsules have recently received increased interest from the life science community, and many interesting systems have appeared in the literature with biodegradable components and biospecific functionalities. In this Review we give an overview of the recent breakthroughs in their application for drug delivery.

  15. A polymeric oxovanadium(IV pyromellitate complex

    Directory of Open Access Journals (Sweden)

    DJORDJE STOJAKOVIC

    1999-09-01

    Full Text Available The reaction of oxovanadium(IV sulphate with 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid in the presence of potassium carbonate yields a polymeric complex, K2[VO(pyr]·6H2O (I [pyr = pyromellitate(4- ion]. The PM3(tm calculations and IR spectroscopy suggest that the polymeric structure of I consists of -V-pyr-V-pyr- chains formed by the 1,4- or 1,5-bridging by the pyr ions. The chains are additionally cross-linked by the chelate function of one of the COO- groups of the pyr ion. Magnetic measurements do not reveal the presence of antiferromagnetic coupling between the V centers.

  16. Polymeric membrane studied using slow positron beam

    International Nuclear Information System (INIS)

    Hung, W.-S.; Lo, C.-H.; Cheng, M.-L.; Chen Hongmin; Liu Guang; Chakka, Lakshmi; Nanda, D.; Tung, K.-L.; Huang, S.-H.; Lee, Kueir-Rarn; Lai, J.-Y.; Sun Yiming; Yu Changcheng; Zhang Renwu; Jean, Y.C.

    2008-01-01

    A radioisotope slow positron beam has been built at the Chung Yuan Christian University in Taiwan for the research and development in membrane science and technology. Doppler broadening energy spectra and positron annihilation lifetime have been measured as a function of positron energy up to 30 keV in a polyamide membrane prepared by the interfacial polymerization between triethylenetetraamine (TETA) and trimesoyl chloride (TMC) on modified porous polyacrylonitrile (PAN) asymmetric membrane. The multilayer structures and free-volume depth profile for this asymmetric membrane system are obtained. Positron annihilation spectroscopy coupled with a slow beam could provide new information about size selectivity of transporting molecules and guidance for molecular designs in polymeric membranes

  17. Self-folding micropatterned polymeric containers.

    Science.gov (United States)

    Azam, Anum; Laflin, Kate E; Jamal, Mustapha; Fernandes, Rohan; Gracias, David H

    2011-02-01

    We demonstrate self-folding of precisely patterned, optically transparent, all-polymeric containers and describe their utility in mammalian cell and microorganism encapsulation and culture. The polyhedral containers, with SU-8 faces and biodegradable polycaprolactone (PCL) hinges, spontaneously assembled on heating. Self-folding was driven by a minimization of surface area of the liquefying PCL hinges within lithographically patterned two-dimensional (2D) templates. The strategy allowed for the fabrication of containers with variable polyhedral shapes, sizes and precisely defined porosities in all three dimensions. We provide proof-of-concept for the use of these polymeric containers as encapsulants for beads, chemicals, mammalian cells and bacteria. We also compare accelerated hinge degradation rates in alkaline solutions of varying pH. These optically transparent containers resemble three-dimensional (3D) micro-Petri dishes and can be utilized to sustain, monitor and deliver living biological components.

  18. Planar elongation of soft polymeric networks

    DEFF Research Database (Denmark)

    Jensen, Mette Krog; Hassager, Ole; Rasmussen, Henrik K.

    2010-01-01

    A new test fixture for the filament stretch rheometer (FSR) has been developed to measure planar elongation of soft polymeric networks with application towards pressure-sensitive adhesives (PSAs). The concept of this new geometry is to elongate a tube-like sample by keeping the perimeter constant....... To validate this new technique, soft polymeric networks of poly(propylene oxide) (PPO) were investigated during deformation. Particle tracking and video recording were used to detect to what extent the imposed strain rate and the sample perimeter remained constant. It was observed that, by using...... an appropriate choice of initial sample height, perimeter, and thickness, the planar stretch ratio will follow lambda(t) = h(t)/h(0) = exp((epsilon)overdot t), with h(t) being the height at time t and (epsilon)overdot the imposed constant strain rate. The perimeter would decrease by a few percent only, which...

  19. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Hassager, Ole; Kristensen, Susanne Brogaard; Larsen, Johannes Ruben

    1999-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane. The polymeric material is described by an arbitrary combination of a viscoelastic and a purely viscous component to the stress. Some viscoelastic materials described by a Mooney......-Rivlin model show a monotone increasing pressure during inflation of a spherical membrane. These materials develop a homogeneous membrane thickness in agreement with the Considere-Pearson condition. Molecularly based models such as the neo-Hookean, Doi-Edwards or Tom-Pom model show a pressure maximum when...... inflated. Membranes described by these models develop a local thinning of the membrane which may lead to bursting in finite time. (C) 1999 Elsevier Science B.V. All rights reserved....

  20. Radiation-induced emulsion polymerization of tetrafluoroethylene

    International Nuclear Information System (INIS)

    Suwa, Takeshi

    1979-10-01

    The radiation-induced emulsifier-free emulsion polymerization of tetrafluoroethylene (TFE) has been studied at initial pressure 2 - 25 kg/cm 2 and temperature 30 0 - 110 0 C for dose rate 0.57 x 10 4 - 3.0 x 10 4 rad/hr. Polytetrafluoroethylene (PTFE), a hydrophobic polymer, forms as a stable latex in the absence of an emulsifier. Stability of the latex is governed by the dose rate/TFE pressure ratio; it increases with sufficient TFE monomer. PTFE particles produced in this polymerization system are stable due to the carboxyl end groups and adsorption of OH - and HF on the particles. PTFE latex of molecular weight higher than 2 x 10 7 is obtained by addition of a radical scavenger such as hydroquinone. The molecular weight of PTFE can be measured from the heat of crystallization conveniently with high reliability, which was found in the course of study on the melting and crystallization behavior. (author)

  1. Radiation polymerization of tetrafluoroethylene in freon-22

    International Nuclear Information System (INIS)

    Schnautz, N.G.; Thompson, J.C.

    1979-02-01

    The radiation-induced solution-polymerization of tetrafluoroethylene in Freon-22 has been investigated over a temperature range of - 62 degrees celcius to 0 degrees celcius. The rate of polymerization for the in-source process was found to be directly propertional to monomer concentration and an activation energy of only 7,66 kj/mole was calculated. The number-average molecular mass of the product PTFE ranged from 2X10 4 to 6X10 4 and was relatively independent of the usual reaction parameters. The rate of postpolymerization was also found to be directly proportional to monomer concentration. The postpolyerization process did not result in any enchancement of the initial PTFE molecular mass [af

  2. Pharmaceutical Applications of Polymeric Nano materials

    International Nuclear Information System (INIS)

    Wu, L.; Sun, L.

    2011-01-01

    With significant attention focused on nano science and nano technology in recent years, nano materials have been used in a wide variety of applications such as automotive, environmental, energy, catalysis, biomedical, drug delivery, and polymeric industries. Among those fields, the application of nano materials with pharmaceutical science is an emerging and rapidly growing field and has drawn increasing attention recently. Research and development in this field is mainly focused on several aspects such as the discoveries of novel functional nano materials, exploration on nanoparticles with controlled and targeted drug delivery characteristics, and investigation of bio functionalized and diagnostic nano materials. In this special issue, we have invited a few papers related to recent advances in pharmaceutical application of polymeric nano materials

  3. EDOT polymerization at photolithographically patterned functionalized graphene

    Czech Academy of Sciences Publication Activity Database

    Kovaříček, Petr; Drogowska, Karolina; Melníková Komínková, Zuzana; Blechta, Václav; Bastl, Zdeněk; Gromadzki, Daniel; Fridrichová, Michaela; Kalbáč, Martin

    2017-01-01

    Roč. 113, MAR 2017 (2017), s. 33-39 ISSN 0008-6223 R&D Projects: GA MŠk LL1301; GA MŠk(CZ) LM2015073 Grant - others:AVČR PPPLZ(CZ) L200401551 Institutional support: RVO:61388955 Keywords : polymerization * electrochemical doping * graphene Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 6.337, year: 2016

  4. Charpy Impact Test on Polymeric Molded Parts

    OpenAIRE

    Alexandra Raicu

    2012-01-01

    The paper presents the Charpy impact tests on the AcrylonitrileButadiene-Styrene (ABS) polymeric material parts. The Charpy impact test, also known as the Charpy V-notch test, is a standardized strain rate test which determines the amount of energy absorbed by a material during fracture. This is a typical method described in ASTM Standard D 6110. We use for testing an Instron - Dynatup equipment which have a fully integrated hardware and software package that let us capture ...

  5. Emulsion polymerization with high energy radiation

    International Nuclear Information System (INIS)

    Stannett, V.T.; Stahel, E.P.

    1992-01-01

    High energy radiation, particularly that of cobalt-60 or caesium-137 gamma-rays, provides in principle an ideal initiator for emulsion polymerization. The high free radical yields from the radiolysis of the aqueous phase combined with the high kinetic chain lengths associated with emulsion polymerization lead to a highly effective utilization of the radiation. There are other important advantages compared with the use of chemical initiators such as potassium persulfate. These are outlined in the chapter, together with some attendant disadvantages. Radiation-induced initiation is temperature independent, and low temperature polymerizations can be conducted with ease. Monomers that mainly terminate their growing chains by chain transfer to monomer give higher molecular weights at lower temperatures. Industrially, vinyl acetate is an important example of such a monomer, and it has been studied using radiation initiation. Both laboratory and pilot plant studies have been carried out and reported. The results are summarized in this chapter. Styrene is the classical example of a material that under a number of conditions closely obeys the so-called ideal Smith-Ewart kinetics. It has been found that under similar conditions but substituting radiation for potassium persulfate as the initiator, ideal kinetics were closely followed. Most of the conventional and some non-standard vinyl and diene monomers have been studied to some extent with radiation-initiated polymerizations in emulsion. To conserve space however, this chapter presents and discusses the results obtained only with styrene and vinyl acetate, both in laboratory and pilot plant investigations. Other monomers and special situations are referenced either directly or to the other available reviews. (orig.)

  6. Forming of Polymeric Tubular Micro-components

    DEFF Research Database (Denmark)

    Qin, Yi; Zhao, Jie; Anyasodor, Gerald

    2015-01-01

    platform for the production of functional polymeric tubular micro-components. The chapter gives background on the current market and process development trends, followed by description of materials, process configuration, tool design and machine development for each processing technology as well...... as strategy for integration of the technologies and equipment into a common platform. Finally, potential applications of the technologies and facilities developed are highlighted....

  7. Long-time asymptotics for polymerization models

    OpenAIRE

    Calvo, Juan; Doumic, Marie; Perthame, Benoît

    2017-01-01

    This study is devoted to the long-term behavior of nucleation, growth and fragmentation equations, modeling the spontaneous formation and kinetics of large polymers in a spatially homogeneous and closed environment. Such models are, for instance, commonly used in the biophysical community in order to model in vitro experiments of fibrillation. We investigate the interplay between four processes: nucleation, polymeriza-tion, depolymerization and fragmentation. We first revisit the well-known L...

  8. Single-Molecule Visualization of Living Polymerization

    Science.gov (United States)

    2014-02-18

    77 (2011). 11 D. P. Allen , M. M. Van Wingerden & R. H. Grubbs. Well-defined silica-supported olefin metathesis catalysts. Org Lett 11, 1261-1264...magnet position), we can also probe how mechanical tension affects the catalytic kinetics of the polymerization. When the magnets are positioned far...the setup include: two rectangular NdFeB magnets mounted on a rotatable base controlled by a motor via a timing belt , collimated LED illumination

  9. Comparison of potentials for polymeric liquids

    International Nuclear Information System (INIS)

    Jung, Hae Young

    2002-01-01

    Many theories for polymeric liquids are based on the concepts of cell, hole, free volume of lattice etc. In this theories, van der Waals potential, Lennard-Jones 6-12 potential and their modified potentials are commonly used. In this work, Mie(p,6)potential was applied to the Continuous Lattice Fluid Theory (which extends the discrete lattices of Lattice Fluid Theory to classically continuous lattices) and Dee-Walsch's Cell Theory (which modifies Flory's Equation of State Theory). Both of them are known to be successful theories for polymeric liquids. Thus, PVT values changing with p (the exponent in the repulsion potential) were calculated and compared with experimental values. And, calculated values of Lattice Fluid theory, Flory's Equation of State Theory and Cho-Sanchez Theory using perturbation method were also compared. Through the calculated results, van der Waals potential, Lennard-Jones 6-12 potential and Mie(p,6) potential for polymeric liquids were compared with each other

  10. Revisiting the Anionic Polymerization of Methyl Ethacrylate

    Energy Technology Data Exchange (ETDEWEB)

    Kennemur, Justin G. [Department of Chemistry and Biochemistry, Florida State University, Tallahassee FL 32306-4390 USA; Bates, Frank S. [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis MN 55455-0431 USA; Hillmyer, Marc A. [Department of Chemistry, University of Minnesota, Minneapolis MN 55455-0431 USA

    2017-09-26

    Synthesis of poly(methyl ethacrylate), (PMEA), in tetrahydrofuran at -78 °C using anionic polymerization techniques results in high molar mass (>30 kg mol-1), low dispersity (1.3), and high conversion (>81%). The molar masses of a series of samples are consistent with values anticipated by the monomer-to-initiator ratio and conversion. These results represent a significant improvement to earlier reported attempts to prepare PMEA using anionic methods. Successful diblock polymerization of polystyrene-block-PMEA, (PS-PMEA), and poly(4-tert-butylstyrene)-block-PMEA, (PtBS-PMEA), is achieved through sequential anionic polymerization techniques with dispersities as low as 1.06 and segment molar fractions close to those targeted. Broad principal scattering peaks observed by small-angle X-ray scattering (SAXS) for symmetric PS-PMEA at relatively high molar mass (39 kg mol-1) suggests an effective interaction parameter (χeff) that is smaller than for PS-block-poly(methyl methacrylate). On the other hand, PtBS-PMEA block polymers form a well-ordered morphology based on SAXS measurements and is attributable to the more hydrophobic PtBS segment. These results confirm the viability of PMEA as a new constituent in the expanding suite of polymers suitable for preparing nanostructured block polymers.

  11. Protein crystallization on polymeric film surfaces

    Science.gov (United States)

    Fermani, Simona; Falini, Giuseppe; Minnucci, Massimiliano; Ripamonti, Alberto

    2001-04-01

    Polymeric films containing ionizable groups, such as sulfonated polystyrene, cross-linked gelatin films with adsorbed poly- L-lysine or entrapped poly- L-aspartate and silk fibroin with entrapped poly- L-lysine or poly- L-aspartate, have been tested as heterogeneous nucleant surfaces for proteins. Concanavalin A from jack bean and chicken egg-white lysozyme were used as models. It was found that the crystallization of concanavalin A by the vapor diffusion technique, is strongly influenced by the presence of ionizable groups on the film surface. Both the induction time and protein concentration necessary for the crystal nucleation decrease whereas the nucleation density increases on going from the reference siliconized cover slip to the uncharged polymeric surfaces and even more to the charged ones. Non-specific attractive and local interactions between the protein and the film surface might promote molecular collisions and the clustering with the due symmetry for the formation of the crystal nuclei. The results suggest that the studied polymeric film surfaces could be particularly useful for the crystallization of proteins from solutions at low starting concentration, thus using small quantities of protein, and for proteins with very long crystallization time.

  12. Allylthioketone Mediated Free Radical Polymerization of Methacrylates

    Directory of Open Access Journals (Sweden)

    Feng Zhong

    2017-11-01

    Full Text Available By combination of high trapping free radical efficiency of the thioketone and resonance of the allylic radical, a new type of mediating agent, 1,3,3-triphenylprop-2-ene-1-thione (TPPT has been successfully synthesized, and then is used to study controlled free radical polymerization of methacrylates. Very stable TPPT radicals at the end of poly(methyl methacrylate (PMMA are detected in the polymerization of MMA using TPPT and AIBN as the control agent and initiator. The MALDI-TOF MS spectra are used to identify terminal groups of the resultant poly(glycidyl methacrylate (PGMA, and major component of the obtained polymer has the structure, (CH32(CNC-PGMA-C7H9O3. Chain extension reaction tests ascertain formation of the dead polymers during the polymer storage and purification process of the polymers. Owing to very slow fragmentation reaction of the TPPT-terminated polymethacrylate radical and addition reaction of this radical with a primary radical, the growing chain radicals are difficult to be regenerated, leading to an unobvious change of the molecular weight with monomer conversion. The molecular weights of polymers can be controlled by the ratios of monomer/initiator and TPPT/initiator. However, the first order kinetics of the polymerization and the polymers with narrow polydispersity are obtained, and these phenomena are discussed. This study provides useful information on how to design a better controlling agent.

  13. Polymerization initated at sidewalls of carbon nanotubes

    Science.gov (United States)

    Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

    2011-01-01

    The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

  14. Biodegradable Polyelectrolyte Obtained by Radiation Polymerization

    International Nuclear Information System (INIS)

    Craciun, G.; Martin, D.; Manaila, E.; Nemtanu, M.; Brasoveanu, M.; Ighigeanu, D.

    2009-01-01

    Poly electrolytes are water-soluble polymers carrying ionic charge along the polymer chain. Depending upon the charge, these polymers are anionic or cationic. The inherent solid - liquid separating efficiency makes these poly electrolytes a unique class of polymers which find extensive application in potable water, industrial raw and process water, municipal sewage treatment, mineral processing and metallurgy, oil drilling and recovery, etc. Also, due to their ability to produce advanced induced coagulation, a considerable amount of bacteria and viruses are precipitated together with the suspended solids. Especially the acrylamide polymers are very efficacious for water treatment but acrylamide is a toxic monomer and therefore their use are governed by international standards that provide the residual acrylamide monomer content (RAMC) in them be less than 0.05%. Under these circumstances our attention was focused on the following research steps that are presented in this paper: 1) Preparation of a special class of poly electrolytes, named Pn, with very low RAMC values, based on electron beam (EB), microwave (MW) and EB + MW induced co-polymerization of aqueous solutions containing appropriate mixtures of acrylamide (AMD) and acrylic acid (AA) monomers (AMD - AA co-polymers). The Pn were obtained by radiation technology with very small RAMC (under 0.01%) as well as in a wide range of molecular weights and charge densities. Very low AMD monomer content of Pn is due to the major advantages of radiation induced polymerization in aqueous solution containing monomers. Due to water presence in the EB irradiated system, irradiated water radicals facilitate the polymerization process and increase rate and level of monomers conversion in co-polymers. Also, once again, by the presence of water, which absorbs MW energy very strongly, the MW polymerization reaction rate is much enhanced resulting in a reaction time about 50-100 times lowers than by conventional heating. Also

  15. A new lithography of functional plasma polymerized thin films

    International Nuclear Information System (INIS)

    Kim, Sung-O

    2001-01-01

    The preparation of the resist for the vacuum lithography was carried out by plasma polymerization. The resist manufactured by plasma polymerization is a monomer produced by MMA (Methyl methacrylate). The functional groups of MMA appeared in the PPMMA (Plasma Polymerized Methyl methacrylate) as well, and this was confirmed through an analysis using FT-IR. The polymerization rate increased as a function of the plasma power and decreased as a function of the system pressure. The sensitivity and contrast of the plasma polymerized thin films were 15 μC/cm2 and 4.3 respectively. The size of the pattern manufactured by Vacuum Lithography using the plasma polymerized thin films was 100 nm

  16. Synthesis of Glycopolymer Architectures by Reversible-Deactivation Radical Polymerization

    Directory of Open Access Journals (Sweden)

    Ali Ghadban

    2013-05-01

    Full Text Available This review summarizes the state of the art in the synthesis of well-defined glycopolymers by Reversible-Deactivation Radical Polymerization (RDRP from its inception in 1998 until August 2012. Glycopolymers architectures have been successfully synthesized with four major RDRP techniques: Nitroxide-mediated radical polymerization (NMP, cyanoxyl-mediated radical polymerization (CMRP, atom transfer radical polymerization (ATRP and reversible addition-fragmentation chain transfer (RAFT polymerization. Over 140 publications were analyzed and their results summarized according to the technique used and the type of monomer(s and carbohydrates involved. Particular emphasis was placed on the experimental conditions used, the structure obtained (comonomer distribution, topology, the degree of control achieved and the (potential applications sought. A list of representative examples for each polymerization process can be found in tables placed at the beginning of each section covering a particular RDRP technique.

  17. Polyvinyl butyral based solid polymeric electrolytes. Preliminary studies

    Energy Technology Data Exchange (ETDEWEB)

    Gopal, Shaleen; Ramchandran, R.; Agnihotry, Rashmi S.A. [National Physical Laboratory, New Delhi (India)

    1996-01-08

    A series of solid polymeric electrolytes has been prepared based on Polyvinyl Butyral (PVB) with different proportions of LiI salt. These polymeric electrolytes showed high ionic conductivity, which has been investigated as a function of the LiI concentration. The highest conductivity was seen at weight proportions 1:0.15 for PVB:LiI. An electrochromic device fabricated using this polymeric electrolyte showed good switching

  18. Microwave-assisted nitroxide-mediated miniemulsion polymerization of styrene

    International Nuclear Information System (INIS)

    Li Jieai; Zhu Xiulin; Zhu Jian; Cheng Zhenping

    2007-01-01

    Nitroxide-mediated free-radical miniemulsion polymerizations (NMRPs) of styrene were successfully performed under microwave irradiation at 135 o C. The polymerizations proceeded in a controlled manner, yielding polymers that showed an incremental increase in molecular weight with conversion and had narrow molecular weight distributions. The resulting latexes were colloidally stable. The polymerization behavior, molecular weights of polymers and Z-average size of latex particles were also investigated under two different heating methods, microwave irradiation and conventional heating

  19. Polypropylene/graphite nanocomposites by in situ polymerization

    International Nuclear Information System (INIS)

    Milani, Marceo A.; Galland, Giselda B.; Quijada, Raul

    2011-01-01

    This work presents the synthesis of nanocomposites of polypropylene/graphite by in situ polymerization using metallocene catalyst and graphene nanosheets. Initially was analyzed which of the metallocene catalysts rac-Et(Ind) 2 ZrCl 2 or rac-Me 2 Si(Ind) 2 ZrCl 2 produces polypropylene with mechanical properties more relevant. Then it were performed the in situ polymerization reactions to obtain the nanocomposites. The polymeric materials were characterized by XRD, DSC, GPC and DMTA. (author)

  20. Resveratrol immobilization and release in polymeric hydrogels

    International Nuclear Information System (INIS)

    Momesso, Roberta Grazzielli Ramos Alves Passarelli

    2010-01-01

    Resveratrol (3, 4', 5-trihydroxystilbene) is a polyphenolic produced by a wide variety of plants in response to injury and found predominantly in grape skins. This active ingredient has been shown to possess benefits for the health, such as the antioxidant capacity which is related to the prevention of several types of cancer and skin aging. However, the oral bioavailability of resveratrol is poor and makes its topical application interesting. The purpose of this study was to immobilize resveratrol in polymeric hydrogels to obtain a release device for topical use. The polymeric matrices composed of poli(N-vinyl-2-pyrrolidone) (PVP), poly(ethyleneglycol) (PEG) and agar or PVP and glycerol irradiated at 20 kGy dose were physical-chemically characterized by gel fraction and swelling tests and its preliminary biocompatibility by in vitro test of cytotoxicity using the technique of neutral red uptake. Due to low solubility of resveratrol in water, the addition of 2% ethanol to the matrices was verified. All matrices showed a high crosslinking degree, capacity of swelling and the preliminary cytotoxicity test showed nontoxicity effect. The devices were obtained by resveratrol immobilization in polymeric matrices, carried out in a one-or-two-steps process, that is, before or after irradiation, respectively. The one step resveratrol devices were characterized by gel fraction, swelling tests and preliminary biocompatibility, and their properties were maintained even after the resveratrol incorporation. The devices containing 0,05% of resveratrol obtained by one-step process and 0,1% of resveratrol obtained by two-steps process were submitted to the release test during 24 h. Resveratrol quantification was done by high performance liquid chromatography (HPLC). The results obtained in the kinetics of release showed that only the devices obtained by two-step process release the resveratrol, which demonstrate antioxidant capacity after the release. (author)

  1. Nanoporous Polymeric Grating-Based Optical Biosensors (Preprint)

    National Research Council Canada - National Science Library

    Hsiao, Vincent K; Waldeisen, John R; Lloyd, Pamela F; Bunning, Timothy J; Huang, Tony J

    2007-01-01

    .... The fabrication process of the nanoporous polymeric grating involves holographic interference patterning and a functionalized pre-polymer syrup that facilitates the immobilization of biomolecules...

  2. Green polymerization methods: renewable starting materials, catalysis and waste reduction

    National Research Council Canada - National Science Library

    Mathers, Robert T; Meier, Michael A. R

    2011-01-01

    ... Introduction 29 First Generation Furans and their Conversion into Monomers 30 Furfural and Derivatives 30 Monomers from Furfural 31 Hydroxymethylfurfural 35 Green Polymerization Methods : Renewable...

  3. Online observation of emulsion polymerization by fluorescence technique

    CERN Document Server

    Rudschuck, S; Fuhrmann, J

    1999-01-01

    An online observation of local polarity via fluorescence spectroscopy was used to study the formation and growth of polymer particles during an emulsifier-free heterogeneous polymerization. The reaction mixture consisted of styrene dispersed in water and the polymerization was initiated by a macro-initiator (hydrolyzed propene-maleic acid copolymer with t-butyl perester groups). Pyrenyl probes were attached to the backbone of the initiator to analyze the heterogeneous reaction. The experimental results allow a clear distinction of different time regions during the heterogeneous polymerization. Information about the heating period, the latex formation, the particle growth and the final stage of the polymerization process (gel point) were obtained. (11 refs).

  4. Metallocene Catalytic Insertion Polymerization of 1-Silene to Polycarbosilanes

    Science.gov (United States)

    Tian, Yuelong; Ge, Min; Zhang, Weigang; Lv, Xiaoxu; Yu, Shouquan

    2015-11-01

    Metallocene of zirconium were used as a catalyst for an insertion polymerization of 1-methylsilene directly into pre-ceramic precursor polyzirconocenecarbosilane (PZCS) during dechlorination of dichlorodimethylesilane by sodium, which exhibits high catalytic effectiveness with the maximum conversion ratio of polycarbosilane up to 91%. The average molecular weights of polymers synthesized are less than 1400, all with very narrow polymolecularities. The mechanism of catalytic polymerization was assumed to be similar to a coordination insertion polymerization of 1-olefins by metallocenes. The obtained PZCS show high ceramic yields with formation of composite ceramics of ZrC-SiC, which are novel polymeric precursors of ultra-high temperature ceramic (UHTC) fiber and composite.

  5. 21 CFR 872.6070 - Ultraviolet activator for polymerization.

    Science.gov (United States)

    2010-04-01

    ... ultraviolet radiation intended to polymerize (set) resinous dental pit and fissure sealants or restorative... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6070 Ultraviolet activator for...

  6. Investigations in the field of solid state polymerization Pt. 38

    International Nuclear Information System (INIS)

    Hardy, Gy.; Cser, F.; Nyitrai, K.; Fedorova, N.

    1980-01-01

    The stuctural and radiation chemical data of vinyl monomers with long chain paraffinic or cholesteric side groups are critically reviewed. Based on their structural and polymerization kinetical characteristics the monomers may be classified into three groups. Oblique layers are favourable for homogeneous topotactic polymerization. This is characterized by a low activation energy and a radiochemical efficiency very similar to that measured in liquid state polymerization. The tilted layers are not favourable for homogeneous topotactic polymerization. Allyl monomers yield polymers with higher molecular weights in the layer structure than in liquid states. (author)

  7. Polymeric media for tritium fixation. Supplement I

    International Nuclear Information System (INIS)

    Franz, J.A.; Burger, L.L.

    1976-01-01

    Procedures for the fixation of tritium as TH or THO in two different polymeric media are described. The complete procedure for THO fixation in a polyureylene-polyurethane polumer, including polymer molding procedures and leach tests is presented. The catalytic tritiation of polystyrene under very mild conditions using a rhodium catalyst is also described. Thermal stabilities and cost estimates for the polymers examined under this program are discussed. Organic polymers were found to have attractive features for the fixation and storage of concentrated tritium wastes due to the convenience of fixation procedures and favorable properties of the resulting media

  8. Novel hybrid polymeric materials for barrier coatings

    Science.gov (United States)

    Pavlacky, Erin Christine

    Polymer-clay nanocomposites, described as the inclusion of nanometer-sized layered silicates into polymeric materials, have been widely researched due to significant enhancements in material properties with the incorporation of small levels of filler (1--5 wt.%) compared to conventional micro- and macro-composites (20--30 wt.%). One of the most promising applications for polymer-clay nanocomposites is in the field of barrier coatings. The development of UV-curable polymer-clay nanocomposite barrier coatings was explored by employing a novel in situ preparation technique. Unsaturated polyesters were synthesized in the presence of organomodified clays by in situ intercalative polymerization to create highly dispersed clays in a precursor resin. The resulting clay-containing polyesters were crosslinked via UV-irradiation using donor-acceptor chemistry to create polymer-clay nanocomposites which exhibited significantly enhanced barrier properties compared to alternative clay dispersion techniques. The impact of the quaternary alkylammonium organic modifiers, used to increase compatibility between the inorganic clay and organic polymer, was studied to explore influence of the organic modifier structure on the nanocomposite material properties. By incorporating just the organic modifiers, no layered silicates, into the polyester resins, reductions in film mechanical and thermal properties were observed, a strong indicator of film plasticization. An alternative in situ preparation method was explored to further increase the dispersion of organomodified clay within the precursor polyester resins. In stark contrast to traditional in situ polymerization methods, a novel "reverse" in situ preparation method was developed, where unmodified montmorillonite clay was added during polyesterification to a reaction mixture containing the alkylammonium organic modifier. The resulting nanocomposite films exhibited reduced water vapor permeability and increased mechanical properties

  9. Polymeric materials for solar thermal applications

    CERN Document Server

    Köhl, Michael; Papillon, Philippe; Wallner, Gernot M; Saile, Sandrin

    2012-01-01

    Bridging the gap between basic science and technological applications, this is the first book devoted to polymers for solar thermal applications.Clearly divided into three major parts, the contributions are written by experts on solar thermal applications and polymer scientists alike. The first part explains the fundamentals of solar thermal energy especially for representatives of the plastics industry and researchers. Part two then goes on to provide introductory information on polymeric materials and processing for solar thermal experts. The third part combines both of these fields, dis

  10. Measuring Interfacial Polymerization Kinetics Using Microfluidic Interferometry.

    Science.gov (United States)

    Nowbahar, Arash; Mansard, Vincent; Mecca, Jodi M; Paul, Mou; Arrowood, Tina; Squires, Todd M

    2018-03-07

    A range of academic and industrial fields exploit interfacial polymerization in producing fibers, capsules, and films. Although widely used, measurements of reaction kinetics remain challenging and rarely reported, due to film thinness and reaction rapidity. Here, polyamide film formation is studied using microfluidic interferometry, measuring monomer concentration profiles near the interface during the reaction. Our results reveal that the reaction is initially controlled by a reaction-diffusion boundary layer within the organic phase, which allows the first measurements of the rate constant for this system.

  11. Charpy Impact Test on Polymeric Molded Parts

    Directory of Open Access Journals (Sweden)

    Alexandra Raicu

    2012-09-01

    Full Text Available The paper presents the Charpy impact tests on the AcrylonitrileButadiene-Styrene (ABS polymeric material parts. The Charpy impact test, also known as the Charpy V-notch test, is a standardized strain rate test which determines the amount of energy absorbed by a material during fracture. This is a typical method described in ASTM Standard D 6110. We use for testing an Instron - Dynatup equipment which have a fully integrated hardware and software package that let us capture load information at very high speed from the impact tests.

  12. Multilayered Polymeric Photonic Structure for THz applications

    Science.gov (United States)

    Xia, Chen; Kosnosky, Louis; Shan, Jie; Lott, Joseph; Mackey, Matthew; Pethe, Vishwas; Baer, Eric; Hiltner, Anne; Weder, Christoph

    2008-03-01

    Photonic crystal have been widely studied in the visible, and recently become of interest in the THz regime of the electromagnetic spectrum. We have developed a rapid, easy and cost effective method for the preparation of polymeric materials with high refractive indices (RI) for the terahertz (THz) frequencies through extrusion of polymer and nanoparticles of inorganic materials. Using this method, we have fabricated a one-dimensional photonic crystal of polymer/polymer ferroelectric nanoparticles composite with a nearly complete stop band in the THz regime. The result will also be compared to a transfer-matrix calculation

  13. Fiberoptic microphone using a polymeric cavity

    Science.gov (United States)

    Wang, Wei-Chih; Soetanto, William; Gu, Kebin

    2011-04-01

    The fabrication and experimental investigation of a fiberoptic microphone is described. The sensing element is a silicon diaphragm with gold thin film coating that is positioned inside a silicone rubber mold at the end of a single mode optical fiber. Thus, a Fabry-Perot interferometer is formed between the inner fiber and the diaphragm. An acoustic pressure change is detected by using the developed microphone. The polymeric cavity and silicon diaphragm-based system exhibits excellent physicochemical properties with a small, simple, low cost, and lightweight design. The system is also electromagnetic interference / radio frequency interference immunity due to the use of fiberoptics.

  14. Modelling degradation of bioresorbable polymeric medical devices

    CERN Document Server

    Pan, J

    2015-01-01

    The use of bioresorbable polymers in stents, fixation devices and tissue engineering is revolutionising medicine. Both industry and academic researchers are interested in using computer modelling to replace some experiments which are costly and time consuming. This book provides readers with a comprehensive review of modelling polymers and polymeric medical devices as an alternative to practical experiments. Chapters in part one provide readers with an overview of the fundamentals of biodegradation. Part two looks at a wide range of degradation theories for bioresorbable polymers and devices.

  15. Targeted polymeric magnetic nanoparticles for brain imaging

    Science.gov (United States)

    Kirthivasan, Bharat; Singh, Dhirender; Raut, Sangram; Bommana, Murali Mohan; Squillante, Emilio, III; Sadoqi, Mostafa

    2012-03-01

    The purpose of this study was to develop targeted polymeric magnetic nanoparticle system for brain imaging. Near infrared dye indocyanine green (ICG) or p-gycoprotein substrate rhodamine 123 (Rh123) were encapsulated along with oleic acid coated magnetic nanoparticles (OAMNP) in a matrix of poly(lactide-co-glycolide) (PLGA) and methoxy poly(ethyleneglycol)-poly(lactide) (Met-PEG-PLA). The nanoparticles were evaluated for morphology, particle size, dye content and magnetite content. The in vivo biodistribution study was carried out using three groups of six male Sprague Dawley rats each. Group I received a saline solution containing the dye, group II received dye-loaded polymeric magnetic nanoparticles without the aid of a magnetic field, and group III received dye-loaded polymeric magnetic nanoparticles with a magnet (8000 G) placed on the head of the rat. After a preset exposure period, the animals were sacrificed and dye concentration was measured in the brain, liver, kidney, lungs and spleen homogenates. Brain sections were fixed, cryotomed and visualized using fluorescence microscopy. The particles were observed to be spherical and had a mean size of 220 nm. The encapsulation efficiency for OAMNP was 57%, while that for ICG was 56% and for Rh123 was 45%. In the biodistribution study, while the majority of the dose for all animals was found in the liver, kidneys and spleen, group III showed a significantly higher brain concentration than the other two groups (p < 0.001). This result was corroborated by the fluorescence microscopy studies, which showed enhanced dye penetration into the brain tissue for group III. Further studies need to be done to elucidate the exact mechanism responsible for the increased brain uptake of dye to help us understand if the magnetic nanoparticles actually penetrate the blood brain barrier or merely deliver a massive load of dye just outside it, thereby triggering passive diffusion into the brain parenchyma. These results reinforce

  16. Sodium metabisulphite induced polymerization of sickle cell ...

    African Journals Online (AJOL)

    Jane

    2011-07-04

    Jul 4, 2011 ... 1.67, 21.15 ± 1.89 and 24.42 ± 1.09%, 800 mg% of T. catappa at t > 30 s gave values of 2.50 ± 1.93, 5.09 ±. 1.96, 10.00 ± 0.99, 15.38 ± 1.33 ... used for spasms (Morales et al., 1994), fevers, worm infections, kidney dysfuctions .... HbS polymerization above the control/reference values (t. = 180 sec; 100% ...

  17. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Hassager, Ole

    1999-01-01

    We consider the inflation of an axisymmetric polymeric membrane. Some membranes composed of viscoelastic materials described by a Mooney-Rivlin model show a monotone increasingpressure during inflation. These materialsdevelop a homogeneous membrane thickness in agreement with the Considere......-Pearson condition.Molecularly based models such as the neo-Hookean, Doi-Edwards or Tom-Pom model exhibit a pressure maximum when inflated. Membranes described by these models develop local thinning which may lead to bursting in finite time. Chain branching is found to be a stabilizing factor for a polymer membrane...... undergoing inflation....

  18. Diffusive transport in modern polymeric materials

    Energy Technology Data Exchange (ETDEWEB)

    Doering, C.; Bier, M.; Christodoulou, K. [and others

    1996-10-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Polymers, composites, and synthetic modern materials are replacing traditional materials in many older scientific, engineering, commercial, and military applications. This project sought to focus on the new polymeric materials, deriving and analyzing models that predict their seemingly mysterious transport properties. It sought to identify the dominant physical mechanisms and the pertinent dimensionless parameters, produce viable theoretical models, and devise asymptotic and numerical methods for use in specific problems.

  19. Development of Polymeric Coatings for Antifouling Applications

    Science.gov (United States)

    Toumayan, Edward Philip

    Fouling, or the deposition of unwanted material onto a surface, is a serious problem that can impair the function of submerged structures, such as marine-going vessels and underwater equipment. Water filtration membranes are particularly susceptible to fouling due to their microstructure and high water pressure operating conditions. For this reason, there has been considerable interest in developing fouling-resistant, or "antifouling" coatings for membranes, specifically coatings that mitigate fouling propensity while maintain high water flux. Polymer coatings have garnered significant interest in antifouling literature, due to their synthetic versatility and variety, and their promising resistance to a wide range of foulants. However, antifouling research has yet to establish a consistent framework for polymer coating synthesis and fouling evaluation, making it difficult or impossible to compare previously established methodologies. To this end, this work establishes a standardized methodology for synthesizing and evaluating polymer antifouling coatings. Specifically, antifouling coatings are synthesized using a grafting-from polymerization and fouling propensity is evaluated by quartz crystal microbalance with dissipation (QCM-D). Using this framework, a number of different surface functionalization strategies are compared, including grafting-to and grafting-from polymerization. A number of different surface functionalization strategies, including grafting-to and grafting-from, were investigated and the fouling performance of these films was evaluated. Primarily, sulfobetaine methacrylate, and poly(ethylene oxide) methacrylate monomers were investigated, among others. Grafting-to, while advantageous from a characterization standpoint, was ultimately limited to low grafting densities, which did not afford a significant improvement in fouling resistance. However, the higher grafting densities achievable by grafting-from did indicate improved fouling resistance. A

  20. Polymeric biomaterials structure and function, v.1

    CERN Document Server

    Dumitriu, Severian

    2013-01-01

    Biomaterials have had a major impact on the practice of contemporary medicine and patient care. Growing into a major interdisciplinary effort involving chemists, biologists, engineers, and physicians, biomaterials development has enabled the creation of high-quality devices, implants, and drug carriers with greater biocompatibility and biofunctionality. The fast-paced research and increasing interest in finding new and improved biocompatible or biodegradable polymers has provided a wealth of new information, transforming this edition of Polymeric Biomaterials into a two-volume set. This volume

  1. Radiation-induced graft polymerization of amphiphilic monomers with different polymerization characteristics onto hydrophobic polysilane

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hidenori; Iwasaki, Isao; Kunai, Yuichiro [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Sato, Nobuhiro, E-mail: sato-n@rri.kyoto-u.ac.j [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Matsuyama, Tomochika [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

    2011-08-15

    The structures of poly(methyl-n-propylsilane) (PMPrS) amphiphilically modified through {gamma}-ray-induced graft polymerization were investigated with {sup 1}H NMR measurement. By the use of methyl methacrylate (MMA) or diethyl fumarate (DEF) as monomers for the graft polymerization, grafting yield rose with increasing total absorption dose and monomer concentrations, but decreased with increasing dose rate. This result means that grafting yield of modified PMPrS can be controlled by changing irradiation conditions. However, the number of PMMA or PDEF graft chains per PMPrS chain was estimated to be less than 1.0 by analysis of {sup 1}H NMR spectra, and this value was lower than that we had expected. To improve graft density, maleic anhydride (MAH), which is known as a non-homopolymerizable monomer in radical polymerization, was used as a monomer for grafting. As a result, high density grafting (one MAH unit for 4.2 silicon atoms) was attained. It demonstrates that the structure of {gamma}-ray-modified polysilane strongly depends on the polymerization characteristics of grafted monomers.

  2. Novel distributed strain sensing in polymeric materials

    International Nuclear Information System (INIS)

    Abot, Jandro L; Song, Yi; Medikonda, Sandeep; Rooy, Nathan; Schulz, Mark J

    2010-01-01

    Monitoring the state of strain throughout an entire structure is essential to determine its state of stress, detect potential residual stresses after fabrication, and also to help to establish its integrity. Several sensing technologies are presently available to determine the strain in the surface or inside a structure. Large sensor dimensions, complex signal conditioning equipment, and difficulty in achieving a widely distributed system have however hindered their development into robust structural health monitoring techniques. Recently, carbon nanotube forests were spun into a microscale thread that is electrically conductive, tough, and easily tailorable. The thread was integrated into polymeric materials and used for the first time as a piezoresistive sensor to monitor strain and also to detect damage in the material. It is revealed that the created self-sensing polymeric materials are sensitive to normal strains above 0.07% and that the sensor thread exhibits a perfectly linear delta resistance–strain response above 0.3%. The longitudinal gauge factors were determined to be in the 2–5 range. This low cost and simple built-in sensor thread may provide a new integrated and distributed sensor technology that enables robust real-time health monitoring of structures

  3. Polymerization of nitrogen in lithium azide

    Science.gov (United States)

    Wang, Xiaoli; Li, Jianfu; Botana, Jorge; Zhang, Meiguang; Zhu, Hongyang; Chen, Li; Liu, Hongmei; Cui, Tian; Miao, Maosheng

    2013-10-01

    Additional electrons can drastically change the bonding trend of light elements. For example, N atoms in alkali metal azides form the linear N3- anions instead of N2 molecules with the introduction of additional electrons. The effect of the additional electrons on the polymerization of N under pressure is important and thus far unclear. Using first principles density functional methods and the particle swarm optimization structure search algorithm, we systematically study the evolution of LiN3 structures under pressures up to 600 GPa. A stable structure featuring polymerized N under pressures higher than 375 GPa is identified for the first time. It consists of zig-zag N polymer chains that are formed by N5- five-member rings sharing N-N pairs. Throughout the stable pressure range, the structure is insulating and consists of N atoms in sp3 hybridizations. Comparing with the atomic and electronic structures of previous phases, our study completes the structural evolution of LiN3 under pressure and reveals the structural changes which are accompanied and driven by the change of atomic orbital hybridization, first from sp to sp2 and then from sp2 to sp3.

  4. Analysis of radiation polymerization of flame retarder

    International Nuclear Information System (INIS)

    Enomoto, Ichiro; Sawai, Takeshi; Ametani, Kazuo

    1990-01-01

    It was found that when vinyl phosphonate oligomer was irradiated with electron beam, the decrease of thermogravity in three steps arose. It was presumed that the first decrease of weight was due to the vaporization of water. This value is nearly constant independent of dose, but when divided irradiation was carried out, as dose increased, the decrease of weight became less. Fire damages have increased as population concentrates into cities and overcrowding occurs. To make combustible materials as well as the textile products belonging to people flame-retardant has become a social problem. The flame retarders and the method of processing which do not generate harmful gas in combustion are demanded. The practical test on making fibers flame-retardant by using radiation graft polymerization has been carried out since 1984, and the method of processing without generating harmful gas was obtained. It is necessary to elucidate the basic property of flame retarders due to irradiation for further developing the technology of flame retardation. This time, the thermogravimetric change of the flame retarders polymerized with radiation was examined. The experimental method and the results are reported. (K.I.)

  5. Chemical polymerization of aniline in phenylphosphinic acid

    Directory of Open Access Journals (Sweden)

    NICOLETA PLESU

    2005-10-01

    Full Text Available The chemical polymerization of aniline was performed in phenylphosphinic acid (APP medium using ammonium peroxidisulfate as the oxidizing agent, at 0 ºC and 25 ºC. The yield of polyaniline (PANI was about 60–69 %. The polymerization process required an induction time 8–10 times greater than in other acids (hydrochloric, sulfuric. The average density of the obtained polymer was 1.395 g cm-3 for PANI-salt and 1.203 g cm-3 for PANI-base. The acid capacity of PANI depends on the synthesis parameters and the maximum value was 15.02 meq/g polymer. The inherent viscosity of PANI was 0.662 dl/g at aniline/oxidant molar ratios >2 and 0 ºC. The oxidation state was a function of the synthesis parameters and lay between 0.553–0.625, as determined from UV-VIS and titration with TiCl3 data. The PANI samples were characterized by measurements of their density, inherent viscosity, conductivity, acid capacity, FTIR and UV-VIS spectrum, and thermogravimetric data.

  6. Predicting polymeric crystal structures by evolutionary algorithms

    Science.gov (United States)

    Zhu, Qiang; Sharma, Vinit; Oganov, Artem R.; Ramprasad, Ramamurthy

    2014-10-01

    The recently developed evolutionary algorithm USPEX proved to be a tool that enables accurate and reliable prediction of structures. Here we extend this method to predict the crystal structure of polymers by constrained evolutionary search, where each monomeric unit is treated as a building block with fixed connectivity. This greatly reduces the search space and allows the initial structure generation with different sequences and packings of these blocks. The new constrained evolutionary algorithm is successfully tested and validated on a diverse range of experimentally known polymers, namely, polyethylene, polyacetylene, poly(glycolic acid), poly(vinyl chloride), poly(oxymethylene), poly(phenylene oxide), and poly (p-phenylene sulfide). By fixing the orientation of polymeric chains, this method can be further extended to predict the structures of complex linear polymers, such as all polymorphs of poly(vinylidene fluoride), nylon-6 and cellulose. The excellent agreement between predicted crystal structures and experimentally known structures assures a major role of this approach in the efficient design of the future polymeric materials.

  7. Metallophilic interactions in polymeric group 11 thiols

    Science.gov (United States)

    Kolari, Kalle; Sahamies, Joona; Kalenius, Elina; Novikov, Alexander S.; Kukushkin, Vadim Yu.; Haukka, Matti

    2016-10-01

    Three polymeric group 11 transition metal polymers featuring metallophilic interactions were obtained directly via self-assembly of metal ions and 4-pyridinethiol ligands. In the cationic [Cu2(S-pyH)4]n2+ with [ZnCl4]n2- counterion (1) and in the neutral [Ag(S-py) (S-pyH)]n (2) 4-pyridinethiol (S-pyH) and its deprotonated form (S-py) are coordinated through the sulfur atom. Both ligands are acting as bridging ligands linking the metal centers together. In the solid state, the gold(I) polymer [Au(S-pyH)2]Cl (3) consists of the repeating cationic [Au(S-pyH)2]+ units held together by aurophilic interactions. Compound 1 is a zig-zag chain, whereas the metal chains in the structures of 2 and 3 are linear. The protonation level of the thiol ligand had an impact on the crystallization of polymers. Both nature of the metal center and reaction conditions affected the polymerization. QTAIM analysis confirmed direct metal-metal contacts only in polymers 1 and 3. In polymer 2, no theoretical evidence of argentophilic contacts was obtained even though the AgṡṡṡAg distance was found to be less than sum of the Bondi's van der Waals radius of silver.

  8. Strong liquid-crystalline polymeric compositions

    Science.gov (United States)

    Dowell, F.

    1993-12-07

    Strong liquid-crystalline polymeric (LCP) compositions of matter are described. LCP backbones are combined with liquid crystalline (LC) side chains in a manner which maximizes molecular ordering through interdigitation of the side chains, thereby yielding materials which are predicted to have superior mechanical properties over existing LCPs. The theoretical design of LCPs having such characteristics includes consideration of the spacing distance between side chains along the backbone, the need for rigid sections in the backbone and in the side chains, the degree of polymerization, the length of the side chains, the regularity of the spacing of the side chains along the backbone, the interdigitation of side chains in sub-molecular strips, the packing of the side chains on one or two sides of the backbone to which they are attached, the symmetry of the side chains, the points of attachment of the side chains to the backbone, the flexibility and size of the chemical group connecting each side chain to the backbone, the effect of semiflexible sections in the backbone and the side chains, and the choice of types of dipolar and/or hydrogen bonding forces in the backbones and the side chains for easy alignment. 27 figures.

  9. Degradable polymeric materials for osteosynthesis: Tutorial

    Directory of Open Access Journals (Sweden)

    D Eglin

    2008-12-01

    Full Text Available This report summarizes the state of the art and recent developments and advances in the use of degradable polymers devices for osteosynthesis. The current generation of biodegradable polymeric implants for bone repair utilising designs copied from metal implants, originates from the concept that devices should be supportive and as “inert” substitute to bone tissue. Today degradable polymeric devices for osteosynthesis are successful in low or mild load bearing applications. However, the lack of carefully controlled randomized prospective trials that document their efficacy in treating a particular fracture pattern is still an issue. Then, the choice between degradable and non-degradable devices must be carefully weighed and depends on many factors such as the patient age and condition, the type of fracture, the risk of infection, etc. The improvement of the biodegradable devices mechanical properties and their degradation behaviour will have to be achieved to broaden their use. The next generation of biodegradable implants will probably see the implementation of the recent gained knowledge in cell-material interactions and cells therapy, with a better control of the spatial and temporal interfaces between the material and the surrounding bone tissue.

  10. Polymeric Slippery Coatings: Nature and Applications

    Directory of Open Access Journals (Sweden)

    Mohamed A. Samaha

    2014-04-01

    Full Text Available We review recent developments in nature-inspired superhydrophobic and omniphobic surfaces. Water droplets beading on a surface at significantly high static contact angles and low contact-angle hystereses characterize superhydrophobicity. Microscopically, rough hydrophobic surfaces could entrap air in their pores resulting in a portion of a submerged surface with air–water interface, which is responsible for the slip effect. Suberhydrophobicity enhances the mobility of droplets on lotus leaves for self-cleaning purposes, so-called lotus effect. Amongst other applications, superhydrophobicity could be used to design slippery surfaces with minimal skin-friction drag for energy conservation. Another kind of slippery coatings is the recently invented slippery liquid-infused porous surfaces (SLIPS, which are one type of omniphobic surfaces. Certain plants such as the carnivorous Nepenthes pitcher inspired SLIPS. Their interior surfaces have microstructural roughness, which can lock in place an infused lubricating liquid. The lubricant is then utilized as a repellent surface for other liquids such as water, blood, crude oil, and alcohol. In this review, we discuss the concepts of both lotus effect and Nepenthes slippery mechanism. We then present a review of recent advances in manufacturing polymeric and non-polymeric slippery surfaces with ordered and disordered micro/nanostructures. Furthermore, we discuss the performance and longevity of such surfaces. Techniques used to characterize the surfaces are also detailed. We conclude the article with an overview of the latest advances in characterizing and using slippery surfaces for different applications.

  11. Vinylimidazole-Based Asymmetric Ion Pair Comonomers: Synthesis, Polymerization Studies and Formation of Ionically Crosslinked PMMA

    NARCIS (Netherlands)

    Jana, S.; Vasantha, V.A.; Stubbs, L.P.; Parthiban, A.; Vancso, Gyula J.

    2013-01-01

    Vinylimidazole-based asymmetric ion pair comonomers (IPCs) which are free from nonpolymerizable counter ions have been synthesized, characterized and polymerized by free radical polymerization (FRP), atom transfer radical polymerization (ATRP), and reversible addition-fragmentation chain transfer

  12. Controlled free radical polymerization of vinyl acetate with cobalt ...

    Indian Academy of Sciences (India)

    able processes but also to the hydrolysis of environmen- tally friendly polyvinyl alcohol in the film formations, separation and bioprocesses, or coatings (figure 4). 4. Conclusion. The cobalt-mediated controlled radical polymerization of vinyl acetate was studied in bulk. It indicated a faster rate than solution polymerization.

  13. Radiation and thermal polymerization of allyl(p-allylcarbonate) benzoate

    International Nuclear Information System (INIS)

    Lopez-V, D.; Herrera-G, A.M.; Castillo-Rojas, S.

    2011-01-01

    Bulk polymerization of novel allyl(p-allylcarbonate) benzoate was investigated using different sources of energy, such as gamma rays, ultraviolet rays as well as thermal polymerization. The poly(allyl(p-allylcarbonate) benzoate) obtained is a cross-linking, transparent, thermoset polycarbonate. Compositions of the monomer and the polycarbonate were analyzed by infrared spectroscopy, elemental analysis, and 1 H NMR spectroscopy.

  14. Propene bulk polymerization kinetics: Role of prepolymerization and hydrogen

    NARCIS (Netherlands)

    Pater, J.T.M.; Weickert, G.; van Swaaij, Willibrordus Petrus Maria

    2003-01-01

    An experimental setup for the polymerization of liquid propylene was used to carry out main polymerizations with and without a prepolymerization step. Two types of prepolymerization are introduced: at a constant temperature and at rapidly increasing reactor temperatures. With the present catalyst

  15. CoCl 2 reinforced polymeric nanocomposites of conjugated polymer

    Indian Academy of Sciences (India)

    Polyaniline (PANI) was synthesized by chemical oxidative polymerization of aniline using ammonium persulphate as an oxidant in acidic aqueous medium. Cobalt chloride hexahydrate (CoCl2⋅6H2O)-doped PANI composite was synthesized by in-situ oxidative polymerization process by using various concentrations of ...

  16. Structural Analysis of Ciprofloxacin-Carbopol Polymeric Composites ...

    African Journals Online (AJOL)

    Erah

    Structural Analysis of Ciprofloxacin-Carbopol. Polymeric Composites .... prepare a sample for analysis, a glass slide was clipped to the ... shows, both polymeric composite types showed similar diffraction patterns. Structure identification in a diffractogram is usually based on the position of peaks and their relative intensities.

  17. electrocatalytic reduction of oxygen at vapor phase polymerized poly ...

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT. We successfully polymerized poly(3,4-ethylenedioxidethiophene) by vapor phase polymerization technique on rotating glassy carbon disk electrode. The catalytic activity of this electrode towards oxygen reduction reaction was investigated and showed remarkable activity. Rotating disk voltammetry was used to ...

  18. Electrocatalytic reduction of oxygen at vapor phase polymerized ...

    African Journals Online (AJOL)

    We successfully polymerized poly(3,4-ethylenedioxidethiophene) by vapor phase polymerization technique on rotating glassy carbon disk electrode. The catalytic activity of this electrode towards oxygen reduction reaction was investigated and showed remarkable activity. Rotating disk voltammetry was used to study the ...

  19. Ring-Opening Polymerization of Lactides by (Pyrazol-1-ylmethyl ...

    African Journals Online (AJOL)

    While poly(D,L-LA) are predominantly atactic, poly(L-LA) are largely isotactic. All polymerization reactions proceed through coordination insertion mechanism followed by hydrolysis of the end groups. KEYWORDS Zinc and copper complexes, lactide, polymerization, kinetics, mechanism. PDF and Supp files attached ...

  20. Physical methods for initiation of emulsion polymerization processes (review)

    International Nuclear Information System (INIS)

    Averko-Antonovich, I.Yu.; Liakumovich, A.G.

    1994-01-01

    The known and widely used methods for initiation of emulsion polymerization by the exposure of aqueous and organic media to ionizing radiation, plasmoichemical, mechanochemcial, and magnetic treatments, are briefly reviewed. The advantages of radiation-induced emulsion polymerization of vinyl monomers, as compared to the other methods, are pointed out

  1. Radiation-induced cationic polymerization of vinyl ethers in solution

    International Nuclear Information System (INIS)

    Deffieux, A.; Young, J.A.; Hsieh, W.C.; Squire, D.R.; Stannett, V.

    1983-01-01

    The influences of the polymerization media, the monomer and solvent concentrations and the temperature on the radiation-induced polymerization of isopropyl vinyl ether (IPVE) have been studied in detail under super-dry conditions. Rates of polymerization were measured and estimates of the rate constants of polymerization were calculated according to the simplified Hayashi-Williams equation. A comparison of the results with those previously reported for ethyl vinyl ether (EVE) is made. The much higher reactivity of IPVC in low polar solvents is interpreted by a drastic reduction of the polymer intramolecular solvation of the growing chain ends. This is ascribed to the bulkiness of the isopropyl side-chain groups. The radiation-induced polymerization of IPVE in bulk and in various solvents with different physical and solvating properties was studied. This was to obtain further information on the kinetics and the mechanisms involved with this monomer and also the role of the polymerization media. The influence of the monomer and solvent concentrations and of the polymerization temperature on the rate of polymerization have also been investigated. (author)

  2. A Kinetic Study of the Emulsion Polymerization of Vinyl Acetate

    DEFF Research Database (Denmark)

    Friis, N.; Nyhagen, L.

    1973-01-01

    The emulsion polymerization of vinyl acetate was studied at 50°C. It was found that the rate of polymerization was proportional to the 0.5 power of the initiator concentration and the 0.25 power of the number of particles. The number of particles was proportional to the power 0.5 ± 0.05 of the em...

  3. CoCl2 reinforced polymeric nanocomposites of conjugated polymer ...

    Indian Academy of Sciences (India)

    Polyaniline (PANI) was synthesized by chemical oxidative polymerization of aniline using ammonium persulphate as an oxidant in acidic aqueous medium. Cobalt chloride hexahydrate (CoCl2⋅6H2O)-doped PANI composite was synthesized by in-situ oxidative polymerization process by using various concentrations of ...

  4. Preparation of polymer microspheres by radiation-induced polymerization

    International Nuclear Information System (INIS)

    Naka, Y.; Yamamoto, Y.; Yoshida, Y.; Tagawa, S.

    1995-01-01

    Cross-liking monomer, diethylene glycol dimethacrylate gives microspheres from organic solution by radiation-induced polymerization. /One of the remarkable result is that the number of the microspheres is not changing during the polymerization. Ethyl methacrylate, maleic anhydride, styrene and acrylamide are used as comonomers. These comonomers give the microspheres in the range of 0 to 0.4 as mol fractions. (author)

  5. Novel polymer coatings based on plasma polymerized 2-methoxyethyl acrylate

    DEFF Research Database (Denmark)

    Wu, Zhenning; Jiang, Juan; Benter, Maike

    2008-01-01

    synthesized by Atom Transfer Radical Polymerization (ATRP)[3]. This enabled a surface segregation of the more hydrophilic block to the polymer/air interface and enrichment of the surface with PMEA. Here we present another way to modify a surface with this material - plasma polymerization in a low energy...

  6. prepared via atom transfer radical polymerization, reverse atom

    Indian Academy of Sciences (India)

    Synthesis and characterization of poly(2-ethylhexyl acrylate) prepared via atom transfer radical polymerization, reverse atom transfer radical polymerization and ... Zydex Industries, 25-A Gandhi Oil Mill Compound, Gorwa, Vadodara 390 016, India; Rubber Technology Centre, Indian Institute of Technology Kharagpur, ...

  7. Modelling the Load Torques of Electric Drive for Polymerization Process

    Directory of Open Access Journals (Sweden)

    Andrzej Popenda

    2007-01-01

    Full Text Available The problems of mathematical modelling the load torques on shaft of driving motor designed for applications in polymerization reactors are presented in the paper. The real load of polymerization drive is determined as a function of angular velocity. Mentioned function results from friction in roll-formed slide bearing as well as from friction of ethylene molecules with mixer arms in polymerization reactor chamber. Application of mathematical formulas concerning the centrifugal ventilator is proposed to describe the mixer in reactor chamber. The analytical formulas describing the real loads of polymerization drive are applied in mathematical modelling the power unit of polymerization reactor with specially designed induction motor. The numerical analysis of transient states was made on the basis of formulated mathematical model. Examples of transient responses and trajectories resulting from analysis are presented in the paper.

  8. Studies on the polymerization of acrolein oxime, 6

    International Nuclear Information System (INIS)

    Masuda, Seizo; Tamai, Harumi; Ota, Tadatoshi; Torii, Munetomo; Tanaka, Masami.

    1979-01-01

    Radiation-induced polymerization and copolymerization of acrolein oxime are investigated in different solvents and at a wide range of temperature for obtaining information on the reaction mechanism. Acrolein oxime is polymerized ionically, irrespective of dryness of the sample. Arrhenius plots for the polymerization rate, which do not yield a linear relation, can be adequately approximated by two straight lines. An anionic mechanism is operative above the room temperature, while a cationic mechanism predominates below -23 0 C. The reaction in the intermediate temperature range proceeds by a competitive mechanism, and the rate of the anionic and cationic polymerizations becomes equal at the temperature near -5 0 C. The reaction rate is proportional to the square root of dose rate at room temperature and -23 0 C. On the basis of these data, it is proposed that the polymerization of acrolein oxime by γ-irradiation proceeds by free-ionic mechanisms. (author)

  9. Fabrication and manipulation of polymeric magnetic particles with magnetorheological fluid

    International Nuclear Information System (INIS)

    Rodríguez-López, Jaime; Shum, Ho Cheung; Elvira, Luis; Montero de Espinosa, Francisco; Weitz, David A.

    2013-01-01

    Polymeric magnetic microparticles have been created using a microfluidic device via ultraviolet (UV) polymerization of double emulsions, resulting in cores of magnetorheological (MR) fluids surrounded by polymeric shells. We demonstrate that the resultant particles can be manipulated magnetically to achieve triggered rupture of the capsules. This illustrates the great potential of our capsules for triggered release of active ingredients encapsulated in the polymeric magnetic microparticles. - Highlights: ► Polymeric microparticles encapsulating MR fluids have been fabricated. ► A double-emulsion-templated approach using microfluidic techniques has been used. ► The monodisperse microparticles obtained are easily manipulated under magnetic field. ► These microparticles have great potential for encapsulation-and-release applications.

  10. Origins and Development of Initiation of Free Radical Polymerization Processes

    Directory of Open Access Journals (Sweden)

    Dietrich Braun

    2009-01-01

    Full Text Available At present worldwide about 45% of the manufactured plastic materials and 40% of synthetic rubber are obtained by free radical polymerization processes. The first free radically synthesized polymers were produced between 1910 and 1930 by initiation with peroxy compounds. In the 1940s the polymerization by redox processes was found independently and simultaneously at IG Farben in Germany and ICI in Great Britain. In the 1950s the systematic investigation of azo compounds as free radical initiators followed. Compounds with labile C–C-bonds were investigated as initiators only in the period from the end of the 1960s until the early 1980s. At about the same time, iniferters with cleavable S–S-bonds were studied in detail. Both these initiator classes can be designated as predecessors for “living” or controlled free radical polymerizations with nitroxyl-mediated polymerizations, reversible addition fragmentation chain transfer processes (RAFT, and atom transfer radical polymerizations (ATRP.

  11. Initiation of MMA polymerization by iniferters based on dithiocarbamates

    Directory of Open Access Journals (Sweden)

    Jovanović Slobodan M.

    2005-01-01

    Full Text Available Twelve modified dithiocarbamates and a thiuramdisulfide used for the initiation of methyl methacrylate (MMA polymerization were synthesized in this study. The polymerization of MMA was followed by determine the yield and molar mass of the obtained PMMA as a function of polymerization time. Four of the synthesized dithiocarbamates S-benzyl-N,N-dibenzyldithiocarbamate, S-allyl-N,N-dibenzyldithiocarbamate S-benzyl-N,N-diisobutyldithiocarbamate and S-benzoyl-N,N-diisobutyldithiocarbamate, as well as N,N,N',N'-tetrabenzylthiuramdisulfide acted as iniferters. They were active as the initiators of the photo and/or thermally initiated radical polymerization of MMA in bulk and inert solvents (benzene and toluene. S Benzyl - N,N - dibenzyldithiocarbamate can be successfully used for the initiation of MMA polymerization in a polar solvent such as dimethylacetamide.

  12. Actin polymerization contributes to neutrophil chemotactic dysfunction following thermal injury.

    Science.gov (United States)

    Hasslen, S R; Ahrenholz, D H; Solem, L D; Nelson, R D

    1992-11-01

    The agent(s) and mechanism(s) responsible for suppression of neutrophil chemotaxis in association with major thermal injury have not been identified. We have proposed that the reduced random motility characterizing patients' cells may contribute to their generalized chemotactic dysfunction. Here we report that actin polymerization may be responsible for the loss of neutrophil motility associated with major thermal injury. Using a fluorescent ligand specific for polymerized or filamentous actin (NBD-phallacidin) in conjunction with flow cytometry, we have discovered that peripheral blood and exudate neutrophils from patients with major thermal injury contain increased levels of actin in a stably polymerized form. Because cyclic polymerization and depolymerization of actin is essential to cell motility, we suggest that actin polymerization may contribute in a major way to the attenuation of neutrophil random and chemotactic functions induced by major thermal injury.

  13. Cooperative polymerization of α-helices induced by macromolecular architecture

    Science.gov (United States)

    Baumgartner, Ryan; Fu, Hailin; Song, Ziyuan; Lin, Yao; Cheng, Jianjun

    2017-07-01

    Catalysis observed in enzymatic processes and protein polymerizations often relies on the use of supramolecular interactions and the organization of functional elements in order to gain control over the spatial and temporal elements of fundamental cellular processes. Harnessing these cooperative interactions to catalyse reactions in synthetic systems, however, remains challenging due to the difficulty in creating structurally controlled macromolecules. Here, we report a polypeptide-based macromolecule with spatially organized α-helices that can catalyse its own formation. The system consists of a linear polymeric scaffold containing a high density of initiating groups from which polypeptides are grown, forming a brush polymer. The folding of polypeptide side chains into α-helices dramatically enhances the polymerization rate due to cooperative interactions of macrodipoles between neighbouring α-helices. The parameters that affect the rate are elucidated by a two-stage kinetic model using principles from nucleation-controlled protein polymerizations; the key difference being the irreversible nature of this polymerization.

  14. Kinetic and thermal analysis of polymeric materials

    Science.gov (United States)

    Peterson, Jeffery David

    2002-09-01

    Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques have been used to study the thermal degradation of polymeric materials. These polymers were subjected to a variety of heating programs as well as numerous types of atmospheric conditions. The results from these analyses were then used to determine activation energies as a function of an extent of reaction variable, alpha. This technique, known as the model-free isoconversional method, allows for changes in energies to occur as decomposition pathways change. This produces a more realistic means of observing complex kinetic schemes and is a better representation of kinetic analysis. Chapters 1 and 2 provide introductory backgrounds into both polymer chemistry and the isoconversional analysis technique, respectively. A brief description of the research goals and motivations is also discussed. Thermal analysis of pure polystyrene (PS), polyethylene (PE), and polypropylene (PP) samples are presented in Chapter 3. The obtained activation energy dependencies are interpreted in terms of degradation mechanisms. These mechanisms vary greatly according to the gaseous environment in which they were analyzed. The thermal degradation of poly(methyl methacrylate) (PMMA) in both pure nitrogen and in various oxygen-containing atmospheres is discussed in Chapter 4. It was observed that oxygen exhibits a stabilizing effect on PMMA decomposition. Activation energies for these processes, and their mechanistic interpretations, will also be presented. Chapter 5 builds off the understanding gained in Chapter 4 by investigating the char-forming effects of silica gel and potassium carbonate additives on PMMA. These additives are known for their fire-resistant properties when combined in a 3:1 silica gel to potassium carbonate ratio. The effects of these additives, and their respective ratio amounts, on PMMA char formation are reported. Chapters 6 and 7 conclude the dissertation by looking at the thermal

  15. Physical and Chemical Properties of Some Imported Woods and their Degradation by Termites

    OpenAIRE

    Shanbhag, Rashmi R.; Sundararaj, R.

    2013-01-01

    The influence of physical and chemical properties of 20 species of imported wood on degradation of the wood by termites under field conditions was studied. The wood species studied were: Sycamore maple, Acer pseudoplatanus L. (Sapindales: Sapindaceae) (from two countries), Camphor, Dryobalanops aromatic C.F.Gaertner (Malvales: Dipterocarpaceae), Beech, Fagus grandifolia Ehrhart (Fagales: Fagaceae), F. sylvatica L. (from two countries), Oak, Quercus robur L., Ash, Fraxinus angustifolia Vahl (L...

  16. The Evaluation of 3-Dimensional Polymerization Changes of a Denture Resin Utilizing Injection Molding with Water Bath Polymerization and Microwave Polymerization

    Science.gov (United States)

    2016-06-01

    Dimensional change in complete dentures fabricated by injection molding and microwave processing . J Prosthet Dent, 2003. 89(1): p. 37-44. 21. Phoenix...The Evaluation of 3-Dimensional Polymerization Changes of a Denture Resin Utilizing Injection Molding with Water Bath Polymerization and Microwave...Specification 12 regarding working qualities of cured resins: “The polymer, when processed according to the instructions furnished by the manufacturer

  17. LEWIS ACID-CATALYZED POLYMERIZATION OF L-LACTIDE - KINETICS AND MECHANISM OF THE BULK-POLYMERIZATION

    NARCIS (Netherlands)

    NIJENHUIS, AJ; GRIJPMA, DW; PENNINGS, AJ

    1992-01-01

    The kinetics of the L-lactide bulk polymerization was studied using tin(II) bis(2-ethylhexanoate) and zinc bis(2,2-dimethyl-3,5-heptanedionato-O,O'). Up to 80% conversion, the rate of polymerization using tin(II) bis(2-ethylhexanoate) is higher than that with the zinc-containing catalyst, while at

  18. Colloid-templated multisectional porous polymeric fibers.

    Science.gov (United States)

    Song, Jung Hun; Kretzschmar, Ilona

    2008-10-07

    A fabrication method for porous polymeric fibers (PPFs) is reported. We show that a multisectional colloidal crystal can be assembled within a microcapillary by alternating dipping into colloidal solutions of varying size. Subsequent infiltration with curable polymer and washing with suitable solvents results in porous fibers with a cylindrical cross section. Along the length of the fiber, alternating sections of controlled length, pore size, and pore size distribution exist. These fibers present interesting materials for neural scaffolding, catalysis, and possibly photonics if produced with a high degree of crystallinity. The surface pores and bulk porosity of the fibers are characterized by variable-pressure scanning electron microscopy (vp-SEM). Careful analysis shows that the surface pores vary with the colloidal template diameter and polymer infiltration time.

  19. Vegetal fibers in polymeric composites: a review

    Directory of Open Access Journals (Sweden)

    Paulo Henrique Fernandes Pereira

    2015-02-01

    Full Text Available The need to develop and commercialize materials containing vegetal fibers has grown in order to reduce environmental impact and reach sustainability. Large amounts of lignocellulosic materials are generated around the world from several human activities. The lignocellulosic materials are composed of cellulose, hemicellulose, lignin, extractives and ashes. Recently these constituents have been used in different applications; in particular, cellulose has been the subject of numerous works on the development of composite materials reinforced with natural fibers. Many studies have led to composite materials reinforced with fibers to improve the mechanical, physical, and thermal properties. Furthermore, lignocellulosic materials have been treated to apply in innovative solutions for efficient and sustainable systems. This paper aims to review the lignocellulosic fibers characteristics, as well as to present their applications as reinforcement in composites of different polymeric matrices.

  20. Dipeptide catalysed prebiotic polymerization of RNA

    DEFF Research Database (Denmark)

    Wieczorek, Rafal; Luisi, Pier Luigi; Monnard, Pierre-Alain

    2011-01-01

    toward more peptide synthesis. In the present work we describe a prebiotically plausible system in which the SerHis dipeptide acts as catalyst for the formation of RNA oligomers from imidazole derivatives of mononucleotides. The thermodynamic shift towards condensation was achieved using water......-concentrated in the remaining liquid microinclusions, thus creating an environment with low water activity in which condensation reactions can occur. Successful oligomerization of RNA monomers catalysed by the SerHis dipeptide was observed in a broad range of pH, and with all four natural nucleobases. The isomeric dipeptide...... HisSer did not exhibit any catalytic properties thus indicating that the specific, spatial arrangement of amino acid residues in the SerHis structure is responsible for its catalytic activity. Establishing novel synthetic pathways to RNA polymerization is important, as to date no convincing prebiotic...

  1. Polymeric molecular sieve membranes for gas separation

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Sheng; Qiao, Zhenan; Chai, Songhai

    2017-08-15

    A porous polymer membrane useful in gas separation, the porous polymer membrane comprising a polymeric structure having crosslinked aromatic groups and a hierarchical porosity in which micropores having a pore size less than 2 nm are present at least in an outer layer of the porous polymer membrane, and macropores having a pore size of over 50 nm are present at least in an inner layer of the porous polymer membrane. Also described are methods for producing the porous polymer membrane in which a non-porous polymer membrane containing aromatic rings is subjected to a Friedel-Crafts crosslinking reaction in which a crosslinking molecule crosslinks the aromatic rings in the presence of a Friedel-Crafts catalyst and organic solvent under sufficiently elevated temperature, as well as methods for using the porous polymer membranes for gas or liquid separation, filtration, or purification.

  2. Heterogeneous Initiators for Sustainable Polymerization Processes

    Science.gov (United States)

    Jones, Matthew D.

    One of the main challenges facing the twenty-first century is the need to produce chemicals from renewable resources. The dwindling supplies of fossil fuels coupled with instability in supply mean that technologies that were once deemed too expensive are now becoming more economically viable options. The majority of man-made polymers are derived from crude oil based monomers. However, in recent years a tremendous effort has been channeled into the preparation of polymers from sustainable chemicals. Two classic examples are polylactide (derived from corn starch) and polycarbonates (prepared directly from CO2). This chapter serves as an introduction into these two polymers and reviews the literature associated with heterogeneous catalyst for the polymerizations, concentrating on approaches describing the heterogenization of homogeneous catalysts.

  3. Final Technical Report: Collaborative Research. Polymeric Muliferroics

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Shenqiang [Univ. of Kansas, Lawrence, KS (United States)

    2015-06-05

    The goal of this project is to investigate room temperature magnetism and magnetoelectric coupling of polymeric multiferroics. A new family of organic charge-transfer complexes has been emerged as a fascinating opportunity for the development of all-organic electrics and spintronics due to its weak hyperfine interaction and low spin-orbit coupling; nevertheless, direct observations of room temperature magnetic spin ordering have yet to be accomplished in organic charge-transfer complexes. Furthermore, room temperature magnetoelectric coupling effect hitherto known multiferroics, is anticipated in organic donor-acceptor complexes because of magnetic field effects on charge-transfer dipoles, yet this is also unexplored. The PIs seek to fundamental understanding of the synthetic control of organic complexes to demonstrate and explore room temperature multiferroicity.

  4. DETECTION OF COMPLEXES OLIGODEOXYNUCLEOTIDES WITH POLYMERIC CARRIERS

    Directory of Open Access Journals (Sweden)

    V. V. Vlizlo

    2013-10-01

    Full Text Available The new method for detection of cationic oligoelectrolytes conjugates with oligodeoxyonucleotides, based on free diffusion of these substances in 0.8% agarose gels is developed. It enables to simplify and reduce the cost of visual identification of the best carrier among various polymer compounds and to uncover the fact of complex formation between the interacting agents resulting in formation of a ring precipitation. The universality of the proposed methodological approach is confirmed by interaction of coligodeoxynucleotides with other cationic polymer of natural origin, namely chitosan. Comparative analysis of our approach applicationto turbidimetry data concerning coligodeoxynucleotides complexes and their electrophoresis showed some advantages, among them are the ability to screen simultaneously a large number of polymeric carriers and no need for using of more expensive equipment and materials. To conclude the complexing occurrence it is enough nanomol amounts of oligodeoxynucleotide.

  5. Negative differential resistance in heterojunction polymeric films

    Science.gov (United States)

    Rathi, Sonika; Gupta, Saral K.; Negi, Chandra Mohan Singh; Singh, Amarjeet

    2018-02-01

    For the first time, Negative Differential Resistance (NDR) is reported in purely polymeric systems. A tri-layer thin film system of PEDOT:PSS, P3HT and PCBM was prepared using spin coating method on ITO substrates and Al contact was deposited on other side using thermal vacuum evaporation. Current -Voltage (I-V) measurements were carried out at room temperature where NDR behaviour was observed which was repeatable only qualitatively for as-prepared device. On annealing at 40 °C for 2 h, the NDR became stable however at the cost of peak broadening and was even repeatable quantitatively within reasonable percentage of errors. On further annealing at higher temperatures (60° & 80° C), the NDR disappeared most likely due to isolated networks and disconnected domains of P3HT/PCBM. Simple construction, robust NDR and large current shown by these devices make them potential candidate for the development of organic memory elements.

  6. Influence of air humidity on polymeric microresonators

    International Nuclear Information System (INIS)

    Schmid, S; Kühne, S; Hierold, C

    2009-01-01

    The influence of air humidity on polymeric microresonators is investigated by means of three different resonator types. SU-8 microbeams, SU-8 microstrings and a silicon micromirror with SU-8 hinges are exposed to relative humidities between 3% and 60%. The shifts of the resonant frequencies as a function of the relative humidity (RH) are explained based on mechanical models which are extended with water absorption models in polymer materials. The dominant effect causing the resonant frequency change is evaluated for each structure type. The eigenfrequency of the microstrings and the micromirror in the out-of-plane mode, which both mainly are defined by the pre-stress of the polymeric structures, are found to be highly sensitive to changes of air humidity. The humidity-induced (hygrometric) volume expansion reversibly reduces the pre-stress which results in relative frequency changes of up to 0.78%/%RH for the microstrings. A maximum coefficient of humidity-induced volume expansion for SU-8 of α hyg = 52.3 ppm/%RH is evaluated by fitting the data with the analytical model. It was found that microstrings that were stored at 150 °C over 150 h are more moisture sensitive compared to structures that were stored at room temperature. For the SU-8 microbeams and the micromirror in the tilt mode, the eigenfrequency is mainly defined by the modulus of the polymer material. The measured relative resonant frequency changes were below 1% for the given RH range. For low RH values, antiplasticization is observed (the modulus increases) followed by a plasticization for increasing RH values

  7. Fluorination of silicone rubber by plasma polymerization

    Science.gov (United States)

    Fielding, Jennifer Chase

    Plasma polymerized fluorocarbon (PPFC) films were deposited onto various silicone rubber substrates, including O-rings, to decrease oil uptake. Depositions were performed using a radio frequency (rf)-powered plasma reactor and various fluorocarbon monomers, such as C2F6, C2F 5H, C3F6, and 1H,1H,2H-perfluoro-1-dodecene. PPFC films which were most promising for inhibiting oil uptake were deposited with 1H,1H,2H-perfluoro-1-dodecene, and were composed predominantly of perfluoromethylene (CF2) species. These films displayed low critical surface energies (as low as 2.7 mJ/m2), and high contact angles with oil (84°), which were correlated with the amount of CF2 species present in the film. For the films with the highest degree of CF2 (up to 67%), CF2 chains may have been oriented slightly perpendicular to the substrate and terminated by CF3 species. Adhesion of the PPFC films directly to silicone rubber was found to be poor. However, when a plasma polymerized hydrocarbon interlayer was deposited on the silicone rubber prior to the fluorocarbon films, adhesion was excellent. O-rings coated with multilayer fluorocarbon films showed 2.6% oil uptake after soaking in oil for 100 hrs at 100°C. Due to variability in data, and the low quality of the industrial grade silicone rubber, the oil uptake mechanism was determined to be from oil flowing through flaws in the film due to defects within the substrate, not from generalized diffusion through the film. This mechanism was confirmed using higher quality silicone rubber, which showed little or no oil diffusion. Therefore, this film may perform well as an oil-repelling barrier when deposited on a high quality silicone rubber.

  8. Utilización del polvo de acería de horno de arco eléctrico. // Use of powder produced by electric arc furnaces at steel plants.

    Directory of Open Access Journals (Sweden)

    D. Tápanes Robau

    2001-01-01

    Full Text Available El polvo de las Acerías de Horno de Arco Eléctrico se produce como consecuencia de la producción de Acero, durante ladepuración de los gases, y, en menor medida, en sus equipos de captación de aire. Estos polvos deben ser captados por lossistemas de depuración del taller. Con el presente trabajo pretendemos darle utilidad a un producto de desecho como es elpolvo, mejorar las condiciones ambientales en el taller, elevar la calidad del pavimento u hormigón asfáltico mediante lavariación de sus propiedades y disminuir el costo de la tonelada de acero mediante la comercialización de estos productosde desecho.Palabras claves: Polvos, aglutinantes, composición química, pruebas realizadas._______________________________________________________________________________SummaryThe powder generated by electric arc furnaces at steel plants is the result of processes such as the production of steel, thepurification of gases and, capturing air equipment .This article shows a method for recycling waste material – powder in this case- which also contributes to improve the steelplant environment, provides the possibility of improving asphalt paving and makes the production of steel cheaper throughthe commercialization of waste materials.Key words: Powder, binder, tests, chemical composition.

  9. Micro-fluidic partitioning between polymeric sheets for chemical amplification and processing

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Brian L.

    2017-01-24

    A system for fluid partitioning for chemical amplification or other chemical processing or separations of a sample, comprising a first dispenser of a first polymeric sheet, wherein the first polymeric sheet contains chambers; a second dispenser of a second polymeric sheet wherein the first dispenser and the second dispenser are positioned so that the first polymeric sheet and the second polymeric sheet become parallel; a dispenser of the fluid positioned to dispense the fluid between the first polymeric sheet and the second polymeric sheet; and a seal unit that seals the first polymeric sheet and the second polymeric sheet together thereby sealing the sample between the first polymeric sheet and the second polymeric sheet and partitioning the fluid for chemical amplification or other chemical processing or separations.

  10. Radiation-induced polymerization of some vinyl compounds

    International Nuclear Information System (INIS)

    Panta, P.; Gluszewski, W.; Zimek, Z.; Wojtynska, E.K.

    1998-01-01

    Complete text of publication follows. The action of accelerator electron beams (E.B.) and Co-60 gamma rays in inducing polymerization of monomers and oligomers of 2-ethylhexyl acrylate, acrylic acid and vinyl acetate was investigated. Using 10 MeV and 10 kW E.B. the time of free radical polymerization as short as several seconds was evaluated. The second order kinetics of polymerization reactions is proposed. Life times of free radicals generated during irradiation of 2-ethylhexyl acrylate, acrylic acid and vinyl acetate are very short at room temperature. For ESR measurements suitable samples were irradiated at 77 K and measured during defrosting. According to available literature data and own results the radiation-induced polymerization of above mentioned vinyl compounds is stopped during EB irradiation, without post effect. Besides polymerization of individual compounds we observe also mutual co-polymerization of appropriate mixtures of 2-ethylhexyl acrylate with acrylic acid and also vinyl acetate. Product of such co-polymerization exhibit some adhesive properties

  11. Probing actin polymerization by intermolecular cross-linking

    OpenAIRE

    1988-01-01

    We have used N,N'-1,4-phenylenebismaleimide, a bifunctional sulfhydryl cross-linking reagent, to probe the oligomeric state of actin during the early stages of its polymerization into filaments. We document that one of the first steps in the polymerization of globular monomeric actin (G-actin) under a wide variety of ionic conditions is the dimerization of a significant fraction of the G-actin monomer pool. As polymerization proceeds, the yield of this initial dimer ("lower" dimer with an app...

  12. Polymeric drugs: Advances in the development of pharmacologically active polymers

    Science.gov (United States)

    Li, Jing; Yu, Fei; Chen, Yi; Oupický, David

    2015-01-01

    Synthetic polymers play a critical role in pharmaceutical discovery and development. Current research and applications of pharmaceutical polymers are mainly focused on their functions as excipients and inert carriers of other pharmacologically active agents. This review article surveys recent advances in alternative pharmaceutical use of polymers as pharmacologically active agents known as polymeric drugs. Emphasis is placed on the benefits of polymeric drugs that are associated with their macromolecular character and their ability to explore biologically relevant multivalency processes. We discuss the main therapeutic uses of polymeric drugs as sequestrants, antimicrobials, antivirals, and anticancer and anti-inflammatory agents. PMID:26410809

  13. Atom transfer radical polymerization of styrene under pulsed microwave irradiation

    International Nuclear Information System (INIS)

    Cheng Zhenping; Zhu Xiulin; Zhou Nianchen; Zhu Jian; Zhang Zhengbiao

    2005-01-01

    A homogeneous solution atom transfer radical polymerization (ATRP) and reverse atom transfer radical polymerization (RATRP) of styrene (St) in N,N-dimethylformamide (DMF) were successfully carried out under pulsed microwave irradiation (PMI), using 1-bromo-1-phenylethane (1-PEBr)/CuCl/N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA) as an initiating system at 85 deg. C and 2,2'-azo-bis-isobutyrontrile (AIBN)/CuCl 2 /PMDETA as an initiating system at 95 deg. C, respectively. The polymerization rates under PMI were greatly increased in comparison with those under identical conventional heating (CH)

  14. Optical Properties of the Self-Assembling Polymeric Colloidal Systems

    Directory of Open Access Journals (Sweden)

    Alexandra Mocanu

    2013-01-01

    Full Text Available In the last decade, optical materials have gained much interest due to the high number of possible applications involving path or intensity control and filtering of light. The continuous emerging technology in the field of electrooptical devices or medical applications allowed the development of new innovative cost effective processes to obtain optical materials suited for future applications such as hybrid/polymeric solar cells, lasers, polymeric optical fibers, and chemo- and biosensing devices. Considering the above, the aim of this review is to present recent studies in the field of photonic crystals involving the use of polymeric materials.

  15. Intrinsic embedded sensors for polymeric mechatronics: flexure and force sensing.

    Science.gov (United States)

    Jentoft, Leif P; Dollar, Aaron M; Wagner, Christopher R; Howe, Robert D

    2014-02-25

    While polymeric fabrication processes, including recent advances in additive manufacturing, have revolutionized manufacturing, little work has been done on effective sensing elements compatible with and embedded within polymeric structures. In this paper, we describe the development and evaluation of two important sensing modalities for embedding in polymeric mechatronic and robotic mechanisms: multi-axis flexure joint angle sensing utilizing IR phototransistors, and a small (12 mm), three-axis force sensing via embedded silicon strain gages with similar performance characteristics as an equally sized metal element based sensor.

  16. Intrinsic Embedded Sensors for Polymeric Mechatronics: Flexure and Force Sensing

    Directory of Open Access Journals (Sweden)

    Leif P. Jentoft

    2014-02-01

    Full Text Available While polymeric fabrication processes, including recent advances in additive manufacturing, have revolutionized manufacturing, little work has been done on effective sensing elements compatible with and embedded within polymeric structures. In this paper, we describe the development and evaluation of two important sensing modalities for embedding in polymeric mechatronic and robotic mechanisms: multi-axis flexure joint angle sensing utilizing IR phototransistors, and a small (12 mm, three-axis force sensing via embedded silicon strain gages with similar performance characteristics as an equally sized metal element based sensor.

  17. Hybrid polymerization of iso-butyl vinyl ether

    Science.gov (United States)

    Jiang, Bo; Yang, Lixing; Zhou, Yong; Huang, Guanglin; Lin, Libin

    2002-03-01

    The radiation-induced hybrid polymerization in the presence of the N-alkoxypyridinium salt having relatively stable nonnucleophilic anion (PF 6-) has been investigated in the paper. Based on the analysis of experimental data and the GPC spectrum, the onium salts not only oxidize α-alkoxyalkyl radicals, produced from IBVE in dichloromethane by irradiation, to the corresponding cations, but also give nonnucleophilic anions PF 6- for the polymerization system. The experimental results clearly demonstrate that free radical and cationic polymerization mechanisms occurred simultaneously in IBVE/EMP +PF 6-/CH 2Cl 2 systems on irradiation with γ-ray.

  18. A model of frontal polymerization using complex initiation

    Directory of Open Access Journals (Sweden)

    P. M. Goldfeder

    1999-01-01

    Full Text Available Frontal polymerization is a process in which a spatially localized reaction zone propagates into a monomer, converting it into a polymer. In the simplest case of free-radical polymerization, a mixture of monomer and initiator is placed in a test tube. A reaction is then initiated at one end of the tube. Over time, a self-sustained thermal wave, in which chemical conversion occurs, is produced. This phenomenon is possible because of the highly exothermic nature of the polymerization reactions.

  19. Mechanistic insights on acrylate insertion polymerization.

    Science.gov (United States)

    Guironnet, Damien; Caporaso, Lucia; Neuwald, Boris; Göttker-Schnetmann, Inigo; Cavallo, Luigi; Mecking, Stefan

    2010-03-31

    Complexes [{(PwedgeO)PdMe}(n)] (1(n); PwedgeO = kappa(2)-P,O-Ar(2)PC(6)H(4)SO(2)O with Ar = 2-MeOC(6)H(4)) are a single-component precursor of the (PwedgeO)PdMe fragment devoid of additional coordinating ligands, which also promotes the catalytic oligomerization of acrylates. Exposure of 1(n) to methyl acrylate afforded the two diastereomeric chelate complexes [(PwedgeO)Pd{kappa(2)-C,O-CH(C(O)OMe)CH(2)CH(C(O)OMe)CH(2)CH(3)}] (3-meso and 3-rac) resulting from two consecutive 2,1-insertions of methyl acrylate into the Pd-Me bond with the same or opposite stereochemistry, respectively, in a 3:2 ratio as demonstrated by comprehensive NMR spectroscopic studies and single crystal X-ray diffraction. These six-membered chelate complexes are direct key models for intermediates of acrylate insertion polymerization, and also ethylene-acrylate copolymerization to high acrylate content copolymers. Studies of the binding of various substrates (pyridine, dmso, ethylene and methyl acrylate) to 3-meso and 3-rac show that hindered displacement of the chelating carbonyl moiety by pi-coordination of incoming monomer significantly retards, but does not prohibit, polymerization. For 3-meso,3-rac + C(2)H(4) right arrow over left arrow 3-meso-C(2)H(4,) 3-rac-C(2)H(4) an equilibrium constant K(353 K) approximately 2 x 10(-3) L mol(-1) was estimated. Reaction of 3-meso, 3-rac with methyl acrylate afforded higher insertion products [(PwedgeO)Pd(C(4)H(6)O(2))(n)Me] (n = 3, 4) as observed by electrospray ionization mass spectrometry (ESI-MS). Theoretical studies by DFT methods of consecutive acrylate insertion provide relative energies of intermediates and transition states, which are consistent with the aforementioned experimental observations, and give detailed insights to the pathways of multiple consecutive acrylate insertions. Acrylate insertion into 3-meso,3-rac is associated with an overall energy barrier of ca. 100 kJ mol(-1).

  20. Method of preparing water purification membranes. [polymerization of allyl amine as thin films in plasma discharge

    Science.gov (United States)

    Hollahan, J. R.; Wydeven, T. J., Jr. (Inventor)

    1974-01-01

    Allyl amine and chemically related compounds are polymerized as thin films in the presence of a plasma discharge. The monomer compound can be polymerized by itself or in the presence of an additive gas to promote polymerization and act as a carrier. The polymerized films thus produced show outstanding advantages when used as reverse osmosis membranes.

  1. Extraction, quantification and degree of polymerization of yacon ...

    African Journals Online (AJOL)

    Extraction, quantification and degree of polymerization of yacon (Smallanthus sonchifolia) fructans. EWN da Fonseca Contado, E de Rezende Queiroz, DA Rocha, RM Fraguas, AA Simao, LNS Botelho, A de Fatima Abreu, MABCMP de Abreu ...

  2. Methods for examination of antigenicity of heterogeneous polymerized hemoglobin

    International Nuclear Information System (INIS)

    Chen Lin; Zhang Yadong; Bu Fengrong; Zhang Jingang

    2004-01-01

    Objective: To choose and establish the methods for examination of heterogeneous polymerized hemoglobin in order to offer the reference for evaluating the antigenicity of heterogeneous polymerized hemoglobin against human. Methods: Antigenicity of heterogeneous polymerized hemoglobin was examined for hypersensitivity, cell-mediated immunity reaction, humoral immunity reaction and cross-reaction of antigen. Results: The rabbit and guinea pig did not give rise to hypersensitivity. In immunized rabbits, the level of serum total IgG was normal, but the level of serum specific IgG was high. The examination of B lymphocytes showed that there was no significant difference (P>0.05) in comparison with control. Cross-reaction of antigen proved that bovine hemoglobin had cross-reaction with human hemoglobin. Suggesting that they may be homologous, the level of the serum specific antibody is high in the immunized animal. According to the immunology theories, the polymerized hemoglobin has antigenicity. (authors)

  3. Reversible and Irreversible Binding of Nanoparticles to Polymeric Surfaces

    Directory of Open Access Journals (Sweden)

    Wolfgang H. Binder

    2009-01-01

    Full Text Available Reversible and irreversible binding of CdSe-nanoparticles and nanorods to polymeric surfaces via a strong, multiple hydrogen bond (= Hamilton-receptor/barbituric acid is described. Based on ROMP-copolymers, the supramolecular interaction on a thin polymer film is controlled by living polymerization methods, attaching the Hamilton-receptor in various architectures, and concentrations. Strong binding is observed with CdSe-nanoparticles and CdSe-nanorods, whose surfaces are equipped with matching barbituric acid-moieties. Addition of polar solvents, able to break the hydrogen bonds leads to the detachment of the nanoparticles from the polymeric film. Irreversible binding is observed if an azide/alkine-“click”-reaction is conducted after supramolecular recognition of the nanoparticles on the polymeric surface. Thus reversible or irreversible attachment of the nanosized objects can be achieved.

  4. Biocompatible Polymeric Materials Intended for Drug Delivery and Therapeutic Applications

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Javakhishvili, Irakli; Bednarek, Melania

    2007-01-01

    With the advent of the controlled free radical polymerization techniques and the novel highly efficient coupling technique (“click chemistry”1) a number of new design principles for biomedical polymeric materials emerge. We’ve recently initiated a comprehensive research programme aiming at elucid......With the advent of the controlled free radical polymerization techniques and the novel highly efficient coupling technique (“click chemistry”1) a number of new design principles for biomedical polymeric materials emerge. We’ve recently initiated a comprehensive research programme aiming...... in formulated drugs. Examples of combinations of PMEA with PMMA or PEG will be elaborated. Similarly combinations of PCL with PAA (prepared from a protected precursor polymer) or PEG will be provided....

  5. Polymer degradation during radiation-induced emulsion polymerization of styrene

    International Nuclear Information System (INIS)

    Sato, K.; Rudin, A.; Huang, R.Y.M.

    1976-01-01

    Styrene was polymerized in emulsion with initiation by γ-rays at a dose rate of 0.6 Mrad/hr. Polymerization rates were as expected from previous reports by others. No branching or crosslinking was detectable, and the anti M/sub w//anti M/sub n/ ratio of the polystyrene did not change significantly during the course of the polymerization reaction. The molecular weight of the product polymer decreased with increasing conversion, in contrast to the behavior of chemically initiated emulsion polymerizations. Monomer-free polystyrene does not degrade under the same radiation conditions, and the progressive decrease of polymer molecular weight with conversion is shown to result from the presence of monomer

  6. Extraction of structural extracellular polymeric substances from aerobic granular sludge

    NARCIS (Netherlands)

    Felz, S.; Al-zuhairy, S.H.K.; Aarstad, Olav Andreas; van Loosdrecht, Mark C.M.; Lin, Y.

    2016-01-01

    To evaluate and develop methodologies for the extraction of gel-forming extracellular polymeric substances (EPS), EPS from aerobic granular sludge (AGS) was extracted using six different methods (centrifugation, sonication, ethylenediaminetetraacetic acid (EDTA), formamide with sodium hydroxide

  7. In Situ Polymerization via Environmentally-Borne Initiation Stimuli

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of my research is to develop novel polymeric materials that solidify upon exposure to an environmentally-borne initiation stimulus. Specifically, I propose...

  8. Novel polymeric nanocomposites and porous materials prepared using organogels

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Wei-Chi; Tseng, Shen-Chen, E-mail: wclai@mail.tku.edu.t [Department of Chemical and Materials Engineering, Tamkang University, 151 Ying-chuan Road, Tamsui, Taipei 25137, Taiwan (China)

    2009-11-25

    We propose a new method for preparing polymeric nanocomposites and porous materials using self-assembled templates formed by 1,3:2,4-dibenzylidene sorbitol (DBS) organogels. DBS is capable of self-assembling into a 3D nanofibrillar network at relatively low concentrations in some organic solvents to produce organogels. In this study, we induced the formation of such physical cross-linked networks in styrene. Subsequently, we polymerized the styrene in the presence of chemical cross-linkers, divinyl benzene (DVB), with different amounts of DBS using thermal-initiated polymerization. The resulting materials were transparent, homogeneous polystyrene (PS) nanocomposites with both physical and chemical cross-links. The porous polymeric materials were obtained by solvent extraction of the DBS nanofibrils from the PS. Brunauer-Emmett-Teller (BET) measurements show that the amounts of DBS and DVB influenced the specific surface area after the removal of the DBS fibrils.

  9. Hafnium metallocene catalyst for the polymerization of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Ewen, J.A.

    1988-12-27

    A catalyst is described for the polymerization and copolymerization of olefins comprising a an alumoxane and chiral, stereorigid hafnium metallocene catalyst. It includes a cyclopentadienyl ring and germanium, silicon, phosphorus, nitrogen, boron, and aluminum radicals.

  10. Growth Kinetics of Monodisperse Polystyrene Microspheres Prepared by Dispersion Polymerization

    Directory of Open Access Journals (Sweden)

    Fan Li

    2013-01-01

    Full Text Available Dispersion polymerization has been widely applied to the synthesis of monodisperse micron-sized polymer colloidal spheres. Many efforts have been devoted to studying the influence of initial conditions on the size and uniformity of the resultant microspheres, aiming to synthesize micron-size monodisperse colloidal spheres. However, the inner contradiction between the size and the size distribution of colloidal spheres hinders the realization of this goal. In this work, we drew our attention from the initial conditions to the growth stage of dispersion polymerization. We tracked the size evolution of colloidal sphere during the dispersion polymerization, through which we established a kinetic model that described the relationship between the monomer concentration and the reaction time. The model may provide a guideline to prepare large polymer colloidal spheres with good monodispersity by continuous monomer feeding during the growth stage to maintain the concentration of monomer at a constant value in a dispersion polymerization process.

  11. Use of polymeric dyes in lignin biodegradation assays

    International Nuclear Information System (INIS)

    Gold, M.H.; Alic, M.; Glenn, J.K.

    1988-01-01

    This paper reviews the historical use of various 14 C-radiolabeled and unlabeled substrates to screen for ligninolytic activity. The disadvantages of these assays are presented. The authors describe the development of assays utilizing polymeric dyes

  12. Crack Behaviour in Polymeric Composites: The Influence of Particle Shape

    Czech Academy of Sciences Publication Activity Database

    Majer, Z.; Hutař, Pavel; Knésl, Zdeněk

    2011-01-01

    Roč. 465, - (2011), s. 564-567 ISSN 1013-9826 Institutional research plan: CEZ:AV0Z20410507 Keywords : polymeric particulate composites * rigid particles * soft interphase Subject RIV: JL - Materials Fatigue, Friction Mechanics

  13. γ-radiation-induced solution polymerization of some methyl aryloxymethacrylates

    International Nuclear Information System (INIS)

    Devarajan, Ramaswamy; Balakrishnan, Thaikkannu; Santappa, M.; Viswanathan, Balasubramanian.

    1981-01-01

    The kinetics of γ-radiation-induced solution polymerization of methyl phenoxymethacrylate (MPMA) and methyl p-cresoxymethacrylate (MCMA) in toluene has been studied at 30 and 0 0 C and at dose rates of 0.3, 0.15, and 0.75 Mrad h -1 . The rates of polymerization, which were found to increase with increasing monomer concentration, have direct dependence on dose rate and [monomer] and have inverse dependence on [solvent]. The apparent energies of activation measured at 0.3 Mrad h -1 for MPMA and MCMA respectively are: 46.8 kJ mol -1 and 11.7 kJ mol -1 . The polymerization proceeded in spite of the presence of the inhibitor p-hydroxyphenyl methyl ether (PHME). This suggests that the mechanism of polymerization may be predominantly ionic. A suitable reaction scheme has been proposed. (author)

  14. Highly reflective polymeric substrates functionalized utilizing atomic layer deposition

    Science.gov (United States)

    Zuzuarregui, Ana; Coto, Borja; Rodríguez, Jorge; Gregorczyk, Keith E.; Ruiz de Gopegui, Unai; Barriga, Javier; Knez, Mato

    2015-08-01

    Reflective surfaces are one of the key elements of solar plants to concentrate energy in the receivers of solar thermal electricity plants. Polymeric substrates are being considered as an alternative to the widely used glass mirrors due to their intrinsic and processing advantages, but optimizing both the reflectance and the physical stability of polymeric mirrors still poses technological difficulties. In this work, polymeric surfaces have been functionalized with ceramic thin-films by atomic layer deposition. The characterization and optimization of the parameters involved in the process resulted in surfaces with a reflection index of 97%, turning polymers into a real alternative to glass substrates. The solution we present here can be easily applied in further technological areas where seemingly incompatible combinations of polymeric substrates and ceramic coatings occur.

  15. Transfer coating by electron initiated polymerization

    Science.gov (United States)

    Nablo, Sam V.

    The high speed and depth of cure possible with electron initiated monomer/oligomer coating systems provide many new opportunities for approaches to product finishing. Moreover, the use of transfer or cast coating using films or metallic surfaces offers the ability to precisely control the surface topology of liquid film surfaces during polymerization. Transfer coating such as with textiles has been a commercial process for many years and the synergistic addition of EB technology permits the manufacture of unusual new products. One of these, the casting paper used in the manufacture of vinyl and urethane fabrics, is the first EB application to use a drum surface for pattern replication in the coating. In this case the coated paper is cured against, and then released from, an engraved drum surface. Recent developments in the use of plastic films for transfer have been applied to the manufacture of transfer metallized and coated paper and paperboard products for packaging. Details of these and related processes will be presented as well as a discussion of the typical product areas (e.g. photographic papers, release papers, magnetic media) using this high speed transfer technology.

  16. Ultrafast ion sieving using nanoporous polymeric membranes.

    Science.gov (United States)

    Wang, Pengfei; Wang, Mao; Liu, Feng; Ding, Siyuan; Wang, Xue; Du, Guanghua; Liu, Jie; Apel, Pavel; Kluth, Patrick; Trautmann, Christina; Wang, Yugang

    2018-02-08

    The great potential of nanoporous membranes for water filtration and chemical separation has been challenged by the trade-off between selectivity and permeability. Here we report on nanoporous polymer membranes with an excellent balance between selectivity and permeability of ions. Our membranes are fabricated by irradiating 2-μm-thick polyethylene terephthalate Lumirror® films with GeV heavy ions followed by ultraviolet exposure. These membranes show a high transport rate of K + ions of up to 14 mol h -1  m -2 and a selectivity of alkali metal ions over heavy metal ions of >500. Combining transport experiments and molecular dynamics simulations with a polymeric nanopore model, we demonstrate that the high permeability is attributable to the presence of nanopores with a radius of ~0.5 nm and a density of up to 5 × 10 10  cm -2 , and the selectivity is ascribed to the interaction between the partially dehydrated ions and the negatively charged nanopore wall.

  17. Intermolecular Structural Change for Thermoswitchable Polymeric Photosensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Park, Wooram; Park, Sin-Jung [Center; Cho, Soojeong; Shin, Heejun [Center; Jung, Young-Seok [Center; Lee, Byeongdu [X-ray; Na, Kun [Center; Kim, Dong-Hyun

    2016-08-17

    A switchable photosensitizer (PS), which can be activated at a spe-cific condition beside light, has tremendous advantages for photo-dynamic therapy (PDT). Herein, we developed a thermo-switchable polymeric photosensitizer (T-PPS) by conjugating PS (Pheophor-bide-a, PPb-a) to a temperature-responsive polymer backbone of biocompatible hydroxypropyl cellulose (HPC). Self-quenched PS molecules linked in close proximity by pi-pi stacking in T-PPS were easily transited to an active monomeric state by the tempera-ture induced phase transition of polymer backbones. The tempera-ture responsive inter-molecular interaction changes of PS molecules in T-PPS were demonstrated in synchrotron small-angle X-ray scattering (SAXS) and UV-Vis spectrophotometer analysis. The T-PPS allowed switchable activation and synergistically enhanced cancer cell killing effect at the hyperthermia temperature (45 °C). Our developed T-PPS has the considerable potential not only as a new class of photomedicine in clinics but also as a biosensor based on temperature responsiveness.

  18. Polymeric gels for intravaginal drug delivery.

    Science.gov (United States)

    Cook, Michael T; Brown, Marc B

    2018-01-28

    Intravaginal drug delivery can elicit a local effect, or deliver drugs systemically without hepatic first pass metabolism. There are a number of emerging areas in intravaginal drug delivery, but the vagina is a challenging route of administration, due to the clearance mechanisms present which result in poor retention of dosage forms, and the potential for irritation and other adverse reactions. Gel formulations are desirable due to the ease of application, spreading and that they cause little to no discomfort to the patient. However, these dosage forms, in particular, are poorly retained and traditional gels typically have little control over drug release rates. This has led to a large number of studies on improving the retention of vaginal gels and modulating the controlled release of drugs from the gel matrix. This review outlines the anatomy and physiology of the vagina, focussing on areas relevant to drug delivery. Medical applications of vaginally administered medicines is then discussed, followed by an overview of polymeric gels in intravaginal drug delivery. The sensorial properties of intravaginal gels, and how these relate to user compliance are also summarised. Finally, some important barriers to marketing approval are described. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. BIORESORBABLE POLYMERIC MENISCAL PROSTHESIS: STUDY IN RABBITS

    Science.gov (United States)

    Cardoso, Tulio Pereira; de Rezende Duek, Eliana Aparecida; Amatuzzi, Marco Martins; Caetano, Edie Benedito

    2015-01-01

    Objective: To induce growth of a neomeniscus into the pores of a prosthesis in order to protect the knee joint cartilage. Methods: 70 knees of 35 New Zealand rabbits were operated. The rabbits were five to seven months old, weighed 2 to 3.8 kilograms, and 22 were male and 13 were female. Each animal underwent medial meniscectomy in both knees during a single operation. A bioabsorbable polymeric meniscal prosthesis composed of 70% polydioxanone and 30% L-lactic acid polymer was implanted in one side. The animals were sacrificed after different postoperative time intervals. The femoral condyles and neomeniscus were subjected to histological analysis. Histograms were used to measure the degradation and absorption of the prosthesis, the growth of meniscal tissue in the prosthesis and the degree of degradation of the femoral condyle joint cartilage. Results: The data obtained showed that tissue growth histologically resembling a normal meniscus occurred, with gradual absorption of the prosthesis, and the percentages of chondrocytes on the control side and prosthesis side. Conclusion: Tissue growth into the prosthesis pores that histologically resembled the normal rabbit meniscus was observed. The joint cartilage of the femoral condyles on the prosthesis side presented greater numbers of chondrocytes in all its layers. PMID:27022549

  20. Graft polymerization of glycidylmethacrylate onto coralline hydroxyapatite.

    Science.gov (United States)

    Murugan, R; Panduranga Rao, K

    2003-01-01

    Graft polymerization of glycidylmethacrylate (GMA) onto coralline hydroxyapatite (CHA) was carried out using potassium persulfate (K2S2O8) and sodium metabisulfite (Na2S2O5) as initiators in aqueous medium. To optimize the reaction conditions for getting maximum grafting yield, the concentrations of backbone, monomer, initiator, temperature and time were varied. The percent grafting was found to increase initially and then gradually decrease with respect to reaction parameters. The results obtained imply that the optimum temperature and time was 60 degrees C and 180 min, respectively, to obtain higher grafting yield. The grafting results have been discussed and a mechanism involved in the grafting of GMA onto CHA is described. The grafted materials were analyzed with Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) measurements. The results of FT-IR confirmed the presence of epoxy group on the grafted CHA. The XRD pattern showed that there was no secondary phase in the apatite lattice due to chemical modification.

  1. Polymeric and Ceramic Nanoparticles in Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Aura-Ileana Moreno-Vega

    2012-01-01

    Full Text Available Materials in the nanometer size range may possess unique and beneficial properties, which are very useful for different medical applications including stomatology, pharmacy, and implantology tissue engineering. The application of nanotechnology to medicine, known as nanomedicine, concerns the use of precisely engineered materials at this length scale to develop novel therapeutic and diagnostic modalities. Nanomaterials have unique physicochemical properties, such as small size, large surface area to mass ratio, and high reactivity, which are different from bulk materials of the same composition. Polymeric and ceramic nanoparticles have been extensively studied as particulate carriers in the pharmaceutical and medical fields, because they show promise as drug delivery systems as a result of their controlled- and sustained-release properties, subcellular size, and biocompatibility with tissue and cells. These properties can be used to overcome some of the limitations found in traditional therapeutic and diagnostic agents. Nanotechnology is showing promising developments in many areas and may benefit our health and welfare. However, a wide range of ethical issues has been raised by this innovative science. Many authorities believe that these advancements could lead to irreversible disasters if not limited by ethical guidelines.

  2. Polymeric Biodegradable Stent Insertion in the Esophagus

    Directory of Open Access Journals (Sweden)

    Kai Yang

    2016-04-01

    Full Text Available Esophageal stent insertion has been used as a well-accepted and effective alternative to manage and improve the quality of life for patients diagnosed with esophageal diseases and disorders. Current stents are either permanent or temporary and are fabricated from either metal or plastic. The partially covered self-expanding metal stent (SEMS has a firm anchoring effect and prevent stent migration, however, the hyperplastic tissue reaction cause stent restenosis and make it difficult to remove. A fully covered SEMS and self-expanding plastic stent (SEPS reduced reactive hyperplasia but has a high migration rate. The main advantage that polymeric biodegradable stents (BDSs have over metal or plastic stents is that removal is not require and reduce the need for repeated stent insertion. But the slightly lower radial force of BDS may be its main shortcoming and a post-implant problem. Thus, strengthening support of BDS is a content of the research in the future. BDSs are often temporarily effective in esophageal stricture to relieve dysphagia. In the future, it can be expect that biodegradable drug-eluting stents (DES will be available to treat benign esophageal stricture, perforations or leaks with additional use as palliative modalities for treating malignant esophageal stricture, as the bridge to surgery or to maintain luminal patency during neoadjuvant chemoradiation.

  3. Inorganic Surface Modification of Nonwoven Polymeric Substrates

    Science.gov (United States)

    Halbur, Jonathan Chandler

    In this study, atomic layer deposition (ALD), a vapor phase inorganic thin film deposition technique, is used to modify the surface of a range of industrially relevant polymers to enhance surface properties or impart additional functionalities. Several unique demonstrations of polymer surface modification are presented including uniform nanomaterial photodeposition to the surface of nonowoven fabrics and the first application of photocatalytic thin film coated nonwovens for advanced filtration of heavy metals from solution. Recent advances in polymer synthesis and processing technologies have resulted in the production of novel polymer systems with unique chemistries and sub-micron scale dimensions. As a result, advanced fiber systems have received much attention for potential use in a wide range of industrially and medically important applications such as advanced and selective filtration, catalysis, flexible electronics, and tissue engineering. However, tailoring the surface properties of the polymer is still needed in order to realize the full range of advanced applications, which can be difficult given the high complexity and non-uniformity of nonwoven polymeric structures. Uniform and controllable inorganic surface modification of nonwovens allows the introduction or modification of many crucial polymer properties with a wide range of application methods.

  4. One Dimensional Polymeric Organic Photonic Crystals for DFB Lasers

    Directory of Open Access Journals (Sweden)

    F. Scotognella

    2008-01-01

    Full Text Available We present a very simple method to realize a one-dimensional photonic crystal (1D PC, consisting of a dye-doped polymeric multilayer. Due to the high photonic density of states at the edges of the photonic band-gap (PBG, a surface emitting distributed feedback (DFB laser is obtained with this structure. Furthermore, the incidence angle dependence of the PBG of the polymeric multilayer is reported.

  5. Isotope effect in thermodynamic parameters of styrene polymerization

    International Nuclear Information System (INIS)

    Lebedev, B.V.; Lebedev, N.K.; Smirnova, N.N.

    1985-01-01

    Isotope effects in the enthalpy, entropy and Gibbs energy of the styrene polymerization process are detected by adiabatic- and isothermal calorimetry methods. Thermodynamic parameters of styrene- and deuterostyrene polymerization are calculated in the range from 0 to 350 K. Differences in thermodynamic quantities of these processes are explained by the influence of hydrogen substitution by deuterium and constitute: for enthalpy and Gibbs energy 2-3 kJ/mol, for entropy - 2-3 J/(mol x k)

  6. Flexural strength of acrylic resins polymerized by different cycles

    Directory of Open Access Journals (Sweden)

    Débora Barros Barbosa

    2007-10-01

    Full Text Available Despite the large number of studies addressing the effect of microwave polymerization on the properties of acrylic resin, this method has received limited clinical acceptance. This study evaluated the influence of microwave polymerization on the flexural strength of a denture base resin. A conventional heat-polymerized (Clássico, a microwave-polymerized (Onda-Cryl and a autopolymerizing acrylic (Jet resins were used. Five groups were established, according to polymerization cycles: A, B and C (Onda-Cryl, short cycle - 500W/3 min, long - 90W/13 min + 500W/90 sec, and manufacturing microwave cycle - 320W/3 min + 0W/3 min + 720W/3 min; T (Clássico, water bath cycle - 74ºC/9h and Q (Jet, press chamber cycle - 50ºC/15 min at 2 bar. Ten specimens (65 x 10 x 3.3mm were prepared for each cycle. The flexural strength of the five groups was measured using a three-point bending test at a cross-head speed of 5 mm/min. Flexural strength values were analyzed by one-way ANOVA and the Tukey's test was performed to identify the groups that were significantly different at 5% level. The microwave-polymerized groups showed the highest means (p<0.05 for flexural strength (MPa (A = 106.97 ± 5.31; B = 107.57 ± 3.99; C = 109.63 ± 5.19, and there were no significant differences among them. The heat-polymerized group (T showed the lowest flexural strength means (84.40 ± 1.68, and differ significantly from all groups. The specimens of a microwavable denture base resin could be polymerized by different microwave cycles without risk of decreasing the flexural strength.

  7. Electrical and optical properties of monomeric and polymerized fullerenes. Review

    CERN Document Server

    Makarova, T L

    2001-01-01

    Paper presents the survey of properties of monomeric and polymerized fullerenes as materials with semiconducting zone structures. Electronic structure of fullerenes is studied in detail. One analyzes the absorption spectra of fullerenes. Paper contains data on the transport parameters of fullerenes and discusses, as well, models of conductivity in these materials. Peculiar attention is given to the processes occurring in fullerenes under polymerization through photoexcitation, charge transfer and pressure

  8. Comparison Between Standard and Pulsed Coherent Light Polymerization

    OpenAIRE

    Šutalo, Zrinka; Meniga, Andrej; Šutalo, Jozo; Azinović, Davorka; Pichler, Goran

    1993-01-01

    An ever growing amount of photo-curable materials is being used in different fields of dentistry. Standard photopolymerization devices produce about 60% o f monomer conversion in composite resin fillings. In order to improve the quality of polymerization, a series of experiments was made using pulsed laser, because continuous coherent light leads to a higher polymerization shrinkage caused by a temperature rise in the material. Three different experiments were carried out with different shade...

  9. Hyper-cross-linked, hybrid membranes via interfacial polymerization

    OpenAIRE

    Raaijmakers, Michiel

    2015-01-01

    Hyper-cross-linked, hybrid membranes consist of covalent networks of alternating organic and inorganic, or biological groups. This thesis reports on the preparation of such hybrid networks via interfacial polymerization. The structure-property relationships of the hybrid networks depend strongly on the type, size and flexibility of the constituents. The collection of polymers that can be synthesized via interfacial polymerization includes polyamides, polyurethanes, polyureas, polyanilines, po...

  10. Stress wave propagation and mitigation in two polymeric foams

    Science.gov (United States)

    Pradel, Pierre; Malaise, Frederic; Cadilhon, Baptiste; Quessada, Jean-Hugues; de Resseguier, Thibaut; Delhomme, Catherine; Le Blanc, Gael

    2017-06-01

    Polymeric foams are widely used in industry for thermal insulation or shock mitigation. This paper investigates the ability of a syntactic epoxy foam and an expanded polyurethane foam to mitigate intense (several GPa) and short duration (buckling of the matrix and damage of the structure. In the epoxy foam, the compaction is due to the crushing of glass microspheres. Two porous material models successfully represent the macroscopic response of these polymeric foams.

  11. Sieving polymer synthesis by reversible addition fragmentation chain transfer polymerization.

    Science.gov (United States)

    Nai, Yi Heng; Jones, Roderick C; Breadmore, Michael C

    2013-12-01

    Replaceable sieving polymers are the fundamental component for high resolution nucleic acids separation in CE. The choice of polymer and its physical properties play significant roles in influencing separation performance. Recently, reversible addition fragmentation chain transfer (RAFT) polymerization has been shown to be a versatile polymerization technique capable of yielding well defined polymers previously unattainable by conventional free radical polymerization. In this study, a high molecular weight PDMA at 765 000 gmol-1 with a PDI of 1.55 was successfully synthesized with the use of chain transfer agent - 2-propionic acidyl butyl trithiocarbonate (PABTC) in a multi-step sequential RAFT polymerization approach. This study represents the first demonstration of RAFT polymerization for synthesizing polymers with the molecular weight range suitable for high resolution DNA separation in sieving electrophoresis. Adjustment of pH in the reaction was found to be crucial for the successful RAFT polymerization of high molecular weight polymer as the buffered condition minimizes the effect of hydrolysis and aminolysis commonly associated with trithiocarbonate chain transfer agents. The separation efficiency of PABTC-PDMA was found to have marginally superior separation performance compared to a commercial PDMA formulation, POP™-CAP, of similar molecular weight range.

  12. Barnacle cement: a polymerization model based on evolutionary concepts

    Science.gov (United States)

    Dickinson, Gary H.; Vega, Irving E.; Wahl, Kathryn J.; Orihuela, Beatriz; Beyley, Veronica; Rodriguez, Eva N.; Everett, Richard K.; Bonaventura, Joseph; Rittschof, Daniel

    2009-01-01

    Summary Enzymes and biochemical mechanisms essential to survival are under extreme selective pressure and are highly conserved through evolutionary time. We applied this evolutionary concept to barnacle cement polymerization, a process critical to barnacle fitness that involves aggregation and cross-linking of proteins. The biochemical mechanisms of cement polymerization remain largely unknown. We hypothesized that this process is biochemically similar to blood clotting, a critical physiological response that is also based on aggregation and cross-linking of proteins. Like key elements of vertebrate and invertebrate blood clotting, barnacle cement polymerization was shown to involve proteolytic activation of enzymes and structural precursors, transglutaminase cross-linking and assembly of fibrous proteins. Proteolytic activation of structural proteins maximizes the potential for bonding interactions with other proteins and with the surface. Transglutaminase cross-linking reinforces cement integrity. Remarkably, epitopes and sequences homologous to bovine trypsin and human transglutaminase were identified in barnacle cement with tandem mass spectrometry and/or western blotting. Akin to blood clotting, the peptides generated during proteolytic activation functioned as signal molecules, linking a molecular level event (protein aggregation) to a behavioral response (barnacle larval settlement). Our results draw attention to a highly conserved protein polymerization mechanism and shed light on a long-standing biochemical puzzle. We suggest that barnacle cement polymerization is a specialized form of wound healing. The polymerization mechanism common between barnacle cement and blood may be a theme for many marine animal glues. PMID:19837892

  13. A comparison of three dimensional change in maxillary complete dentures between conventional heat polymerizing and microwave polymerizing techniques

    Directory of Open Access Journals (Sweden)

    Shinsuke Sadamori

    2007-03-01

    Full Text Available The purpose of this study was to measure and compare two different polymerizing processes, heat polymerizing (HP and microwave polymerizing (MP, on the three dimensional changes in the fitting surface and artificial teeth of maxillary complete dentures. A threedimensional coordinate measurement system was used to record distortion of the specimens. The distortion of the fitting surface was measured from the reference plane on the fitting side from which a coordinate system was set, and the movement of the artificial teeth and the distortion of the polished surface was measured from the reference plane of the artificial tooth side, from which a coordinate system was set. It was clearly showed that various distortions of denture specimens after polymerization process can be measured with this three-coordinate measuring machine. The study showed that the overall distortion of the fitting surface in HP specimens was shown to be larger than in MP ones.

  14. Process for impregnating a concrete or cement body with a polymeric material

    Science.gov (United States)

    Mattus, Alfred J.; Spence, Roger D.

    1989-01-01

    A process for impregnating cementitious solids with polymeric materials by blending polymeric materials in a grout, allowing the grout to cure, and contacting the resulting solidified grout containing the polymeric materials with an organic mixture containing a monomer, a cross-linking agent and a catalyst. The mixture dissolves the polymerized particles and forms a channel for distributing the monomer throughout the network formed by the polymeric particles. The organic components are then cured to form a substantially water-impermeable mass.

  15. Microencapsulated Comb-Like Polymeric Solid-Solid Phase Change Materials via In-Situ Polymerization

    Directory of Open Access Journals (Sweden)

    Wei Li

    2018-02-01

    Full Text Available To enhance the thermal stability and permeability resistance, a comb-like polymer with crystallizable side chains was fabricated as solid-solid phase change materials (PCMs inside the cores of microcapsules and nanocapsules prepared via in-situ polymerization. In this study, the effects on the surface morphology and microstructure of micro/nanocapsules caused by microencapsulating different types of core materials (i.e., n-hexadecane, ethyl hexadecanoate, hexadecyl acrylate and poly(hexadecyl acrylate were systematically studied via field emission scanning electron microscope (FE-SEM and transmission electron microscope (TEM. The confined crystallization behavior of comb-like polymer PCMs cores was investigated via differential scanning calorimeter (DSC. Comparing with low molecular organic PCMs cores, the thermal stability of PCMs microencapsulated comb-like polymer enhanced significantly, and the permeability resistance improved obviously as well. Based on these resultant analysis, the microencapsulated comb-like polymeric PCMs with excellent thermal stability and permeability resistance showed promising foreground in the field of organic solution spun, melt processing and organic coating.

  16. Self-Propagating Frontal Polymerization in Water at Ambient Pressure

    Science.gov (United States)

    Olten, Nesrin; Kraigsley, Alison; Ronney, Paul D.

    2003-01-01

    Advances in polymer chemistry have led to the development of monomers and initiation agents that enable propagating free-radical polymerization fronts to exist. These fronts are driven by the exothermicity of the polymerization reaction and the transport of heat from the polymerized product to the reactant monomer/solvent/initiator solution. The thermal energy transported to the reactant solution causes the initiator to decompose, yielding free radicals, which start the free radical polymerization process as discussed in recent reviews. The use of polymerization processes based on propagating fronts has numerous applications. Perhaps the most important of these is that it enables rapid curing of polymers without external heating since the polymerization process itself provides the high temperatures necessary to initiate and sustain polymerization. This process also enables more uniform curing of arbitrarily thick samples since it does not rely on heat transfer from an external source, which will necessarily cause the temperature history of the sample to vary with distance from the surface according to a diffusion-like process. Frontal polymerization also enables filling and sealing of structures having cavities of arbitrary shape without having to externally heat the structure. Water at atmospheric pressure is most convenient solvent to employ and the most important for practical applications (because of the cost and environmental issues associated with DMSO and other solvents). Nevertheless, to our knowledge, steady, self-propagating polymerization fronts have not been reported in water at atmospheric pressure. Currently, polymerization fronts require a high boiling point solvent (either water at high pressures or an alternative solvent such as dimethyl sulfoxide (DMSO) (boiling point 189 C at atmospheric pressure.) Early work on frontal polymerization, employed pressures up to 5000 atm in order to avoid boiling of the monomer/solvent/initiator solution. High

  17. Effect of Oxygen and Initiator Solubility on Admicellar Polymerization of Styrene on Silica Surfaces

    Directory of Open Access Journals (Sweden)

    Pohlee Cheah

    2017-01-01

    Full Text Available Although admicellar polymerization has been termed the surface analog of emulsion polymerization, previous reports utilizing free radical-initiated admicellar polymerization relied on high levels of the free radical initiator when compared to emulsion polymerization, likely due to the presence of oxygen in the reported admicellar polymerization systems. Admicellar polymerizations of styrene on the surface of precipitated silica initiated by either a water-soluble or a water-insoluble initiator were studied to determine the effect of dissolved oxygen and free radical initiator solubility on the kinetics, yield, and molecular weight of the polymer formed. Results show that the presence of oxygen reduces the polymer yield and limits molecular weight. The solubility of the initiator also affected the polymer formed in the admicellar polymerization of styrene. While monomer conversions and polymer yield were similar, the molecular weights of polymerizations initiated by a water-soluble initiator were higher than comparable polymerizations initiated by a water-insoluble initiator.

  18. Radiation-induced post polymerization of acrylonitrile in urea canal complex

    International Nuclear Information System (INIS)

    Yoshii, Fumio; Abe, Toshihiko; Yoda, Osamu

    1975-01-01

    Effect of polymerization conditions on the post polymerization of acrylonitrile (I) in its urea canal complex and the molecular weight distribution of the resulting polymer were investigated. The molar ratio of I to urea in the canal complex was estimated as about unity from differential thermal analysis, X-ray powder patterns and polymerization behavior. The post polymerization was observed above -100 0 C. The rate of polymerization increased with raising the polymerization temperature and increasing irradiation dose. The molecular weight (etasub(sp)/C) increased with increasing polymerization temperature and decreasing irradiation dose. The polymer has a relatively sharp distribution of the molecular weight determined by gel permeation chromatography. After the saturation of the polymerization yield the G-value of initiation was independent of the molar ratio of I to urea in the canal complex and the polymerization yield depends on the length of molecular chain. (auth.)

  19. Microfluidic production of polymeric functional microparticles

    Science.gov (United States)

    Jiang, Kunqiang

    This dissertation focuses on applying droplet-based microfluidics to fabricate new classes of polymeric microparticles with customized properties for various applications. The integration of microfluidic techniques with microparticle engineering allows for unprecedented control over particle size, shape, and functional properties. Specifically, three types of microparticles are discussed here: (1) Magnetic and fluorescent chitosan hydrogel microparticles and their in-situ assembly into higher-order microstructures; (2) Polydimethylsiloxane (PDMS) microbeads with phosphorescent properties for oxygen sensing; (3) Macroporous microparticles as biological immunosensors. First, we describe a microfluidic approach to generate monodisperse chitosan hydrogel microparticles that can be further connected in-situ into higher-order microstructures. Microparticles of the biopolymer chitosan are created continuously by contacting an aqueous solution of chitosan at a microfluidic T-junction with a stream of hexadecane containing a nonionic detergent, followed by downstream crosslinking of the generated droplets by a ternary flow of glutaraldehyde. Functional properties of the microparticles can be easily varied by introducing payloads such as magnetic nanoparticles and/or fluorescent dyes into the chitosan solution. We then use these prepared microparticles as "building blocks" and assemble them into high ordered microstructures, i.e. microchains with controlled geometry and flexibility. Next, we describe a new approach to produce monodisperse microbeads of PDMS using microfluidics. Using a flow-focusing configuration, a PDMS precursor solution is dispersed into microdroplets within an aqueous continuous phase. These droplets are collected and thermally cured off-chip into soft, solid microbeads. In addition, our technique allows for direct integration of payloads, such as an oxygen-sensitive porphyrin dye, into the PDMS microbeads. We then show that the resulting dye

  20. Platinum porphyrins as ionophores in polymeric membrane electrodes

    DEFF Research Database (Denmark)

    Lvova, Larisa; Verrelli, Giorgio; Nardis, Sara

    2011-01-01

    A comparative study of Pt(II)- and Pt(IV)-porphyrins as novel ionophores for anion-selective polymeric membrane electrodes is performed. Polymeric membranes of different compositions, prepared by varying plasticizers, cationic and anionic additives and Pt porphyrins, have been examined by potenti......A comparative study of Pt(II)- and Pt(IV)-porphyrins as novel ionophores for anion-selective polymeric membrane electrodes is performed. Polymeric membranes of different compositions, prepared by varying plasticizers, cationic and anionic additives and Pt porphyrins, have been examined...... within the electrode membranes, while those based on Pt(IV)TPPCl2 operate via a mixed mode carrier mechanism, evidencing also a partial reduction of the starting ionophore to Pt(II)TPP. Spectrophotometric measurements of thin polymeric films indicate that no spontaneous formation of hydroxide ion bridged...... porphyrin dimers occurs in the membrane plasticized both with high or low dielectric constant plasticizer, due to a low oxophilicity of central Pt. The computational study of various anion–Pt(IV)TPPCl2 complex formation by means of semi-empirical and density functional theory (DFT) methods revealed a good...

  1. Tubulin polymerization-stimulating activity of Ganoderma triterpenoids.

    Science.gov (United States)

    Kohno, Toshitaka; Hai-Bang, Tran; Zhu, Qinchang; Amen, Yhiya; Sakamoto, Seiichi; Tanaka, Hiroyuki; Morimoto, Satoshi; Shimizu, Kuniyoshi

    2017-04-01

    Tubulin polymerization is an important target for anticancer therapies. Even though the potential of Ganoderma triterpenoids against various cancer targets had been well documented, studies on their tubulin polymerization-stimulating activity are scarce. This study was conducted to evaluate the effect of Ganoderma triterpenoids on tubulin polymerization. A total of twenty-four compounds were investigated using an in vitro tubulin polymerization assay. Results showed that most of the studied triterpenoids exhibited microtuble-stabilizing activity to different degrees. Among the investigated compounds, ganoderic acid T-Q, ganoderiol F, ganoderic acid S, ganodermanontriol and ganoderic acid TR were found to have the highest activities. A structure-activity relationship (SAR) analysis was performed. Extensive investigation of the SAR suggests the favorable structural features for the tubulin polymerization-stimulating activity of lanostane triterpenes. These findings would be helpful for further studies on the potential mechanisms of the anticancer activity of Ganoderma triterpenoids and give some indications on the design of tubulin-targeting anticancer agents.

  2. Grape and wine polymeric polyphenols: Their importance in enology.

    Science.gov (United States)

    Li, Lingxi; Sun, Baoshan

    2017-09-21

    Phenolic compounds are important constituents of red wine, contributing to its sensory properties and antioxidant activity. Owing to the diversity and structural complexity, study of these compounds was mainly limited, during the last three decades, on their low-molecular-mass compounds or simple phenolic compounds. Only in recent years, much attention has been paid to highly polymerized polyphenols in grape and red wines. The reason for this is largely due to the development of analytical techniques, especially those of HPLC-ESI-MS, permitting the structural characterization of highly polymerized polyphenols. Furthermore, the knowledge on the biological properties of polymeric polyphenols of red wine is very limited. Grape polyphenols mainly consist of proanthocyanidins (oligomers and polymers) and anthocyanins, and low amount of other phenolics. Red wine polyphenols include both grape polyphenols and new phenolic products formed from them during winemaking process. This leads to a great diversity of new polyphenols and makes wine polyphenol composition more complex. The present paper summarizes the advances in the research of polymeric polyphenols in grape and red wine and their important role in Enology. Scientific results indicate that polymeric polyphenols, as the major polyphenols in grape and red wine, play a major role in red wine sensory properties, color stability and antioxidant activities.

  3. Linear interfacial polymerization: theory and simulations with dissipative particle dynamics.

    Science.gov (United States)

    Berezkin, Anatoly V; Kudryavtsev, Yaroslav V

    2014-11-21

    Step-growth alternating interfacial polymerization between two miscible or immiscible monomer melts is investigated theoretically and by dissipative particle dynamics simulations. In both cases the kinetics for an initially bilayer system passes from the reaction to diffusion control. The polymer composed of immiscible monomers precipitates at the interface forming a film of nearly uniform density. It is demonstrated that the reaction proceeds in a narrow zone, which expands much slower than the whole film, so that newly formed polymer is extruded from the reaction zone. This concept of "reactive extrusion" is used to analytically predict the degree of polymerization and distribution of all components (monomers, polymer, and end groups) within the film in close agreement with the simulations. Increasing the comonomer incompatibility leads to thinner and more uniform films with the higher average degree of polymerization. The final product is considerably more polydisperse than expected for the homogeneous step-growth polymerization. The results extend the previous theoretical reports on interfacial polymerization and provide new insights into the internal film structure and polymer characteristics, which are important for membrane preparation, microencapsulation, and 3D printing technologies. A systematic way of mapping the simulation data onto laboratory scales is discussed.

  4. Study on irradiated polymerization of acrylonitrile by NMR

    International Nuclear Information System (INIS)

    Zhao Xin; Lin Hao

    1999-01-01

    Sup 13 C CP/MAS spectra and nuclear Overhauser effects (NOE) at room temperature have been measured for acrylonitrile (AN) in homophase irradiated polymerization. With the increase of radiation dose the chemical shift of cracking peaks and NOE are variation. This implies that the polymerized mechanism of AN were changed with the variation of irradiated doses and dose rate. There is the stronger affinity electron group (-CN) in acrylonitrile monomer. It may be polymerized by various ways and mechanism and be gained the polymer of difference structures and molecular weight of polyacrylonitrile (PAN). Starmicarbon and Starker obtained higher molecular weight of polyacrylonitrile by peroxysulfate-pyrosulfite in oxidation-reduction system. The superhigh molecular weight of PAN was synthesized chemically according to the method of Wu et. al. by suspension polymerization. In this paper we discussed that the relative concentrations of steric dyads and triads in the chain structure in PAN and the irradiation polymerized mechanism of acrylonitrile monomer in room temperature by different dose and dose rate

  5. Smart polymeric materials in forms of fiber and film

    International Nuclear Information System (INIS)

    Sugo, Takanobu

    1998-01-01

    Chemical grafting: graft polymerization is a powerful technology to append novel functionality to base fibers, clothes, felts, films and others, while maintaining their original properties. As shown in Figure 1, while a gardener may use a pair of shears to cut the branch, to cut the molecular branch of a polymeric material, one can utilize the radiation energy. Effective utilization of the radiation energy can proceed to a novel reaction that is impossible for other conventional methods and develop a new material bearing outstanding functions. This technology is named radiation-induced graft polymerization (RIGP). In this article, the present research and development of novel functional polymeric materials by radiation-induced graft polymerization is described. The felt of intertwined fibers has been widely used as a filter to remove particles from air but not toxic gaseous compounds. However, by RIGP, one can transform the felt into a high functional filter that will absorb the toxic gaseous compounds while removing particles simultaneously. As a result, the RIGP technology, which is impossible by conventional technology, has enabled the development of a novel functional material that produce highly pure air. Commercialization of this filter for applications in a semiconductor manufacturing facility and as an air purifier is under process. Moreover, this filter can also be used to produce highly purified water by removing toxic heavy metals. Commercially available polyethylene films are also been transform into conductive separators by RIGP to increase the lifetime of a battery by more than five-fold. (J.P.N)

  6. Polymerization of N-(fluoro phenyl) maleimides. [. gamma. radiation

    Energy Technology Data Exchange (ETDEWEB)

    Barrales-Rienda, J.M.; Ramos, J.G.; Chaves, M.S.

    1979-01-01

    Poly(N-aryl maleimide)s of characteristic structures have been synthesized and some of their physical properties studied. The polymerization of N-(fluoro phenyl) maleimides by free-radical initiation in bulk or in solution and by anionic catalyst have been studied to compare the characteristics of polymerization by ..gamma..-ray irradiation with that by free-radical initiation. The polymers were characterized by elemental analysis, intrinsic viscosity, spectroscopy (IR and NMR), programmed thermogravimetric analysis, and x-ray diffraction. Spectra of polymers prepared by radiation and anionic polymerization were nearly identical with those of polymers prepared by free-radical polymerization initiated by azobisisobutyronitrile in bulk or in solution and by the self-initiated thermal polymerization. A variety of reaction conditions were tried, but all attempts to change the molecular structure of the polymers were unsuccessful. Rates of thermal degradation for poly(N-(fluoro phenyl) maleimide)s have been analyzed by using a multiple-heating-rate procedure. Overall activation energy, order of reaction, and frequency factor have been evaluated. 6 figures, 8 tables.

  7. The measurement of polymerization shrinkage of composite resins with ESPI

    Science.gov (United States)

    Zhang, Zhang; Yang, Guo Biao

    2008-09-01

    In the current study, we used the method of electronic speckle pattern interferometry (ESPI) to measure polymerization shrinkage of composite resins. Standardized cavities were prepared and placed into the ESPI apparatus before the cavities were filled with composites (n=2) .The ESPI apparatus was constructed to measure the out-of-plane displacement of the resins surface during the polymerization. Experiments demonstrated that the ESPI technique was a viable method to measure the deformation of composite resins. It was responsive and sensitive to dimensional changes. We found that cavity shape, size and C- factor influenced the date of resins shrinkage. And the tooth deformation in response to polymerization of resins was measured by the ESPI too. We concluded that ESPI was a feasible method for assessing resins deformation induced by its polymerization shrinkage when it was bonded in tooth cavities. And the results were greatly influenced by the dimensions of cavities , or interface adhesive and so on. It could also measure the tooth deformation induced by shrinkage of bonded composite resins. We found that resins polymerization shrinkage date may overestimate shrinkage-induced tooth deformation.

  8. Characterization of polymeric microneedle arrays for transdermal drug delivery.

    Directory of Open Access Journals (Sweden)

    Yusuf K Demir

    Full Text Available Microfabrication of dissolvable, swellable, and biodegradable polymeric microneedle arrays (MNs were extensively investigated based in a nano sensitive fabrication style known as micromilling that is then combined with conventional micromolding technique. The aim of this study was to describe the polymer selection, and optimize formulation compounding parameters for various polymeric MNs. Inverse replication of micromilled master MNs reproduced with polydimethylsiloxane (PDMS, where solid out of plane polymeric MNs were subsequently assembled, and physicochemically characterized. Dissolvable, swellable, and biodegradable MNs were constructed to depth of less than 1 mm with an aspect ratio of 3.6, and 1/2 mm of both inter needle tip and base spacing. Micromolding step also enabled to replicate the MNs very precisely and accurate. Polymeric microneedles (MN precision was ranging from ± 0.18 to ± 1.82% for microneedle height, ± 0.45 to ± 1.42% for base diameter, and ± 0.22 to ± 0.95% for interbase spacing. Although dissolvable sodium alginate MN showed less physical robustness than biodegradable polylactic-co-glycolic acid MN, their thermogravimetric analysis is of promise for constructing these polymeric types of matrix devices.

  9. Cationic two-photon induced polymerization with high dynamic range

    Science.gov (United States)

    Boiko, Yuri B.; Costa, Joannes; Wang, Mark M.; Esener, Sadik C.

    2001-05-01

    Cationic-induced two-photon photo-polymerization is demonstrated at 710 nm, using an isopropylthioxanthone / diarylidonium salt initiating system for the cationic polymerization of an epoxide. In-situ monitoring of the polymer conversion using interferometry allows for determination of the polymerization threshold J2th, polymerization rate R and its dependence of initiator's concentration z. Best J2th achieved is 1 GW/cm 2 , with a dynamic range of > 100, i.e. the material can be fully polymerized at intensities > 100 times the threshold level without damage. The R is found to be proportional to the m=1.7 power of the intensity, or R =[C(J-J2th)]m =[C(J-J2th)]1.7 , which implies a significantly stronger localization of the photochemical response than that of free radical photoinitiators. Both R and J2th significantly improve when the concentration z of the initiator (onium salt) increases, reduction of J2th exhibiting z -m trend.

  10. Highly thermal-stable, plasma-polymerized BCB polymer film

    International Nuclear Information System (INIS)

    Kawahara, J; Nakano, A; Kinoshita, K; Harada, Y; Tagami, M; Tada, M; Hayashi, Y

    2003-01-01

    A new plasma-enhanced organic monomer-vapour polymerization (plasma polymerization) method has been developed. It was used to make a divinyl siloxane bis-benzocyclobutene (DVS-BCB) polymer film for Cu dual-damascene interconnects that had high thermal stability and a low dielectric constant, k = 2.6. The method consists of the vaporization of organic monomers, transportation of monomers in the gas phase, and polymerization by plasma to make the polymer film. The method eliminates polymer oxidation of DVS-BCB during the polymerization in high vacuum, which improves the film's thermal stability. The thermal stability of plasma-polymerized BCB (p-BCB) exceeded 400 deg. C because of the higher deposition temperature, and the film had a high resistance to Cu diffusion at 400 deg. C annealing. The narrow-pitched Cu/BCB damascene lines showed a 35% reduction in line capacitance compared with Cu/SiO 2 ones. The p-BCB is shown to be a strong candidate for Cu/low-k interconnects

  11. Factors affecting toxicity and efficacy of polymeric nanomedicines

    International Nuclear Information System (INIS)

    Igarashi, Eiki

    2008-01-01

    Nanomedicine is the application of nanotechnology to medicine. The purpose of this article is to review common characteristics of polymeric nanomedicines with respect to passive targeting. We consider several biodegradable polymeric nanomedicines that are between 1 and 100 nm in size, and discuss the impact of this technology on efficacy, pharmacokinetics, toxicity and targeting. The degree of toxicity of polymeric nanomedicines is strongly influenced by the biological conditions of the local environment, which influence the rate of degradation or release of polymeric nanomedicines. The dissemination of polymeric nanomedicines in vivo depends on the capillary network, which can provide differential access to normal and tumor cells. The accumulation of nanomedicines in the microlymphatics depends upon retention time in the blood and extracellular compartments, as well as the type of capillary endothelium surrounding specific tissues. Finally, the toxicity or efficacy of intact nanomedicines is also dependent upon tissue type, i.e., non-endocrine or endocrine tissue, spleen, or lymphatics, as well as tumor type

  12. Direct surface PEGylation of nanodiamond via RAFT polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yingge [Department of Chemistry and Jiangxi Provincial Key Laboratory of New Energy Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Liu, Meiying [Department of Chemistry and Jiangxi Provincial Key Laboratory of New Energy Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wang, Ke [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China); Huang, Hongye; Wan, Qing [Department of Chemistry and Jiangxi Provincial Key Laboratory of New Energy Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Tao, Lei [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China); Fu, Lihua [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry and Jiangxi Provincial Key Laboratory of New Energy Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China)

    2015-12-01

    Graphical abstract: In this paper, we describe an efficient, practical and novel method to modify ND via direct immobilization of chain transfer agent for RAFT polymerization. - Highlights: • Surface PEGylation of ND via RAFT polymerization. • ND with high water dispersibility and excellent biocompatibility. • Controlled living polymerization. - Abstract: Nanodiamond (ND) is a novel class of carbon nanomaterials, which has been extensively investigated for biomedical applications because of its small size, high surface area and excellent biocompatibility. However, the biomedical applications of unmodified ND are still largely restricted because of their poor dispersibility in both aqueous and organic medium. In this work, we reported a novel strategy for the surface modification of ND via reversible addition fragmentation chain transfer (RAFT) polymerization. For preparation of the PEGylated ND (pPEGMA-ND), chain transfer agent (CTA) was immobilized onto ND through reaction between the hydroxyl group of ND and the carboxyl group of CTA, which was used as the initiator for surface-initiated RAFT polymerization. The successful preparation of pPEGMA-ND was characterized by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectra and thermal gravimetric analysis in detail. Results demonstrated that pPEGMA-ND exhibited enhanced water dispersibility and desirable biocompatibility, making it promising for biomedical applications.

  13. Polymeric peptide pigments with sequence-encoded properties

    Energy Technology Data Exchange (ETDEWEB)

    Lampel, Ayala; McPhee, Scott A.; Park, Hang-Ah; Scott, Gary G.; Humagain, Sunita; Hekstra, Doeke R.; Yoo, Barney; Frederix, Pim W. J. M.; Li, Tai-De; Abzalimov, Rinat R.; Greenbaum, Steven G.; Tuttle, Tell; Hu, Chunhua; Bettinger, Christopher J.; Ulijn, Rein V.

    2017-06-08

    Melanins are a family of heterogeneous polymeric pigments that provide ultraviolet (UV) light protection, structural support, coloration, and free radical scavenging. Formed by oxidative oligomerization of catecholic small molecules, the physical properties of melanins are influenced by covalent and noncovalent disorder. We report the use of tyrosine-containing tripeptides as tunable precursors for polymeric pigments. In these structures, phenols are presented in a (supra-)molecular context dictated by the positions of the amino acids in the peptide sequence. Oxidative polymerization can be tuned in a sequence-dependent manner, resulting in peptide sequence–encoded properties such as UV absorbance, morphology, coloration, and electrochemical properties over a considerable range. Short peptides have low barriers to application and can be easily scaled, suggesting near-term applications in cosmetics and biomedicine.

  14. Conductive cotton prepared by polyaniline in situ polymerization using laccase.

    Science.gov (United States)

    Zhang, Ya; Dong, Aixue; Wang, Qiang; Fan, Xuerong; Cavaco-Paulo, Artur; Zhang, Ying

    2014-09-01

    The high-redox-potential catalyst laccase, isolated from Aspergillus, was first used as a biocatalyst in the oxidative polymerization of water-soluble conductive polyaniline, and then conductive cotton was prepared by in situ polymerization under the same conditions. The polymerization of aniline was performed in a water dispersion of sodium dodecylbenzenesulfonate (SDBS) micellar solution with atmospheric oxygen serving as the oxidizing agent. This method is ecologically clean and permits a greater degree of control over the kinetics of the reaction. The conditions for polyaniline synthesis were optimized. Characterizations of the conducting polyaniline and cotton were carried out using Fourier transform infrared spectroscopy, UV-vis spectroscopy, cyclic voltammetry, the fabric induction electrostatic tester, and the far-field EMC shielding effectiveness test fixture.

  15. Polymeric salt bridges for conducting electric current in microfluidic devices

    Science.gov (United States)

    Shepodd, Timothy J [Livermore, CA; Tichenor, Mark S [San Diego, CA; Artau, Alexander [Humacao, PR

    2009-11-17

    A "cast-in-place" monolithic microporous polymer salt bridge for conducting electrical current in microfluidic devices, and methods for manufacture thereof is disclosed. Polymeric salt bridges are formed in place in capillaries or microchannels. Formulations are prepared with monomer, suitable cross-linkers, solvent, and a thermal or radiation responsive initiator. The formulation is placed in a desired location and then suitable radiation such as UV light is used to polymerize the salt bridge within a desired structural location. Embodiments are provided wherein the polymeric salt bridges have sufficient porosity to allow ionic migration without bulk flow of solvents therethrough. The salt bridges form barriers that seal against fluid pressures in excess of 5000 pounds per square inch. The salt bridges can be formulated for carriage of suitable amperage at a desired voltage, and thus microfluidic devices using such salt bridges can be specifically constructed to meet selected analytical requirements.

  16. Controlled polymerizations for the synthesis of semiconducting conjugated polymers

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Ken; Luscombe, Christine K.

    2011-01-01

    Conjugated polymers have been under active development since the 1970s as the active material in organic field-effect transistors (OFETs), photovoltaic devices and the emissive layer in light-emitting diodes (LEDs). Extensive work has been performed to investigate the physics and chemistry of these materials, and a variety of semiconducting polymers have been synthesized using a range of polymerization techniques. One of the most important key technologies is to obtain a well-controlled polymerization, which provides polymers with narrow polydispersities and defined molecular weights. In this paper, we describe the recent progress on the synthesis of semiconducting polymers as classified as polyphenylenes, polyphenylenevinylenes, polythiophenes, polyfluorene and their block copolymers by the use of controlled polymerizations.

  17. APPLICATION OF MODEL PREDICTIVE CONTROL TO BATCH POLYMERIZATION REACTOR

    Directory of Open Access Journals (Sweden)

    N.M. Ghasem

    2006-06-01

    Full Text Available The absence of a stable operational state in polymerization reactors that operates in batches is factor that determine the need of a special control system. In this study, advanced control methodology is implemented for controlling the operation of a batch polymerization reactor for polystyrene production utilizingmodel predictive control. By utilizing a model of the polymerization process, the necessary operational conditions were determined for producing the polymer within the desired characteristics. The maincontrol objective is to bring the reactor temperature to its target temperature as rapidly as possible with minimal temperature overshoot. Control performance for the proposed method is encouraging. It has been observed that temperature overshoot can be minimized by the proposed method with the use of both reactor and jacket energy balance for reactor temperature control.

  18. Poly(isobutylene) nanoparticles via cationic polymerization in nonaqueous emulsions.

    Science.gov (United States)

    Schuster, Thomas; Golling, Florian E; Krumpfer, Joseph W; Wagner, Manfred; Graf, Robert; Alsaygh, Abdulhamid A; Klapper, Markus; Müllen, Klaus

    2015-01-01

    The preparation of poly(isobutylene) (PIB) nanoparticles via cationic emulsion polymerization is presented. As a requirement, an oil-in-perfluoroalkane nonaqueous emulsion is developed, which is inert under the carbocationic polymerization conditions. To stabilize the dichloromethane/hexane droplets in the fluorinated, continuous phase, an amphiphilic block copolymer emulsifier is prepared containing PIB and 1H,1H-perfluoroalkylated poly(pentafluorostyrene) blocks. This system allows for the polymerization of isobutylene with number-average molecular weights (Mn) up to 27,000 g mol(-1). The particle morphologies are characterized via dynamic light scattering and electron microscopy. For Mn > 20,000 g mol(-1), the particles exhibit shape-persistence at room temperature and are ≈100 nm in diameter. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Research progress on space charge characteristics in polymeric insulation

    Directory of Open Access Journals (Sweden)

    Yibo Zhang

    2016-03-01

    Full Text Available Due to their excellent electrical insulation properties and processability, polymer materials are used in many electrical products. It is widely believed that space charge plays an important role for the electric field distribution, conduction, ageing, and electric breakdown of polymeric insulation. This paper reviews measurements and characteristics of space charge behavior which mainly determined by the pulsed electro-acoustic (PEA measurement technique. Particular interests are the effects of the applied voltage, the electrodes, temperature, humidity, microstructure, additives, and filler materials on accumulation, distribution, transport, and the decay of space charge in polymeric materials. This review paper is to provide an overview on various space charge effects under different conditions, and also to summarize the information for polymeric materials with suppressed space charge and improved electrical behavior.

  20. Spiral actin-polymerization waves can generate amoeboidal cell crawling

    Energy Technology Data Exchange (ETDEWEB)

    Dreher, A.; Aranson, I. S.; Kruse, K.

    2014-05-01

    Amoeboidal cell crawling on solid substrates is characterized by protrusions that seemingly appear randomly along the cell periphery and drive the cell forward. For many cell types, it is known that the protrusions result from polymerization of the actin cytoskeleton. However, little is known about how the formation of protrusions is triggered and whether the appearance of subsequent protrusions is coordinated. Recently, the spontaneous formation of actin-polymerization waves was observed. These waves have been proposed to orchestrate the cytoskeletal dynamics during cell crawling. Here, we study the impact of cytoskeletal polymerization waves on cell migration using a phase-field approach. In addition to directionally moving cells, we find states reminiscent of amoeboidal cell crawling. In this framework, new protrusions are seen to emerge from a nucleation process, generating spiral actin waves in the cell interior. Nucleation of new spirals does not require noise, but occurs in a state that is apparently displaying spatio-temporal chaos.

  1. Enantioselective Epoxide Polymerization Using a Bimetallic Cobalt Catalyst

    KAUST Repository

    Thomas, Renee M.

    2010-11-24

    A highly active enantiopure bimetallic cobalt complex was explored for the enantioselective polymerization of a variety of monosubstituted epoxides. The polymerizations were optimized for high rates and stereoselectivity, with s-factors (kfast/kslow) for most epoxides exceeding 50 and some exceeding 300, well above the threshold for preparative utility of enantiopure epoxides and isotactic polyethers. Values for mm triads of the resulting polymers are typically greater than 95%, with some even surpassing 98%. In addition, the use of a racemic catalyst allowed the preparation of isotactic polyethers in quantitative yields. The thermal properties of these isotactic polyethers are presented, with many polymers exhibiting high T m values. This is the first report of the rapid synthesis of a broad range of highly isotactic polyethers via the enantioselective polymerization of racemic epoxides. © 2010 American Chemical Society.

  2. Simulation of styrene polymerization reactors: kinetic and thermodynamic modeling

    Directory of Open Access Journals (Sweden)

    A. S. Almeida

    2008-06-01

    Full Text Available A mathematical model for the free radical polymerization of styrene is developed to predict the steady-state and dynamic behavior of a continuous process. Special emphasis is given for the kinetic and thermodynamic models, where the most sensitive parameters were estimated using data from an industrial plant. The thermodynamic model is based on a cubic equation of state and a mixing rule applied to the low-pressure vapor-liquid equilibrium of polymeric solutions, suitable for modeling the auto-refrigerated polymerization reactors, which use the vaporization rate to remove the reaction heat from the exothermic reactions. The simulation results show the high predictive capability of the proposed model when compared with plant data for conversion, average molecular weights, polydispersity, melt flow index, and thermal properties for different polymer grades.

  3. Surface functionalization of polyamide fiber via dopamine polymerization

    Science.gov (United States)

    Kuang, Xiao-Hui; Guan, Jin-Ping; Tang, Ren-Cheng; Chen, Guo-Qiang

    2017-09-01

    The oxidative polymerization of dopamine for the functional surface modification of textile fibers has drawn great attention. In this work, the functionalization of polyamide fiber via dopamine polymerization was studied with the aim of the fabrication of hydrophilic and antistatic surface. The conditions of dopamine application were first discussed in the absence of specific oxidants in terms of the apparent color depth of polyamide fiber. Dopamine concentration, pH and time were found to exert great impact on color depth. The highest color depth was achieved at pH 8.5. In the process of modification, polydopamine was deposited onto the surface of polyamide fiber. The modified polyamide fiber displayed a yellowish brown color with excellent wash and light color fastness, and exhibited good hydrophilic, UV protection and antistatic effects. A disadvantage of the present approach was the slow rate of dopamine polymerization and functionalization.

  4. Effect of ultrasonic pretreatment on emulsion polymerization of styrene.

    Science.gov (United States)

    Nagatomo, Daichi; Horie, Takafumi; Hongo, Chizuru; Ohmura, Naoto

    2016-07-01

    This study investigated the effect of pretreatment of ultrasonic irradiation on emulsion polymerization of styrene to propose a process intensification method which gives high conversion, high reaction rate, and high energy efficiency. The solution containing styrene monomer was irradiated by a horn mounted on the ultrasonic transducer with the diameter of 5mm diameter and the frequency of 28 kHz before starting polymerization. The pretreatment of ultrasound irradiation as short as 1 min drastically improved monomer dispersion and increased reaction rate even under the agitation condition with low rotational speed of impeller. Furthermore, the ultrasonic pretreatment resulted in higher monomer concentration in polymer particles and produced larger polymer particles than conventional polymerization without ultrasonic pretreatment. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Metallocene complexes as homogeneous catalysts in olefin polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Alt, H.G. [Universitaet Bayreuth (Germany)

    1995-01-01

    Ansa metallocene dichloride complexes of titanium, zirconium, and hafnium can be activated by methyl aluminoxane (MAO) to give excellent catalysts for the homogeneous polymerization of ethylene and propylene. The symmetry of the corresponding metallocene dichloride complexes is essential for the stereospecific polymerization of propylene (isotactic, syndiotactic or atactic). The application of fluorenyl groups instead of cyclopentadienyl groups greatly increases the activity of the catalysts. The first ansa bis(fluorenyl) complexes of zirconium and hafnium, (C{sub 13}H{sub 8}-C{sub 2}H{sub 4}-C{sub 13}H{sub 8})MCl{sub 2} (M = Zr, Hf), have been prepared. It was found that after the activation by MAO the zirconium derivative demonstrates a very high activity. Several models are presented in order to discuss the mechanism of the polymerization.

  6. Recent advances on polymeric membranes for membrane reactors

    KAUST Repository

    Buonomenna, M. G.

    2012-06-24

    Membrane reactors are generally applied in high temperature reactions (>400 °C). In the field of fine chemical synthesis, however, much milder conditions are generally applicable and polymeric membranes were applied without their damage. The successful use of membranes in membrane reactors is primary the result of two developments concerning: (i) membrane materials and (ii) membrane structures. The selection of a suited material and preparation technique depends on the application the membrane is to be used in. In this chapter a review of up to date literature about polymers and configuration catalyst/ membranes used in some recent polymeric membrane reactors is given. The new emerging concept of polymeric microcapsules as catalytic microreactors has been proposed. © 2012 Bentham Science Publishers. All rights reserved.

  7. Effects of polymeric carbohydrates on growth and development

    DEFF Research Database (Denmark)

    Knudsen, Knud Erik Bach

    The main objective of the presentation is to provide insight into the role of polymeric carbohydrates in growth and development of pigs. Polymeric carbohydrates—starch and non-starch polysaccharides (NSP)—quantitatively represent the largest portion of the diets for pigs and are therefore...... at a slower and more constant rate and with SCFA being absorbed by passive diffusion. Type and levels of polymeric carbohydrates influence growth and development through different mechanisms; first, the proportion of starch to NSP plays an important role for the content of available energy (digestible......, metabolized and net energy); available energy relative to protein is crucial for performance and carcass quality; second, the proportion of starch to NSP will influence rate and type of metabolites (glucose vs. SCFA) deriving from carbohydrate assimilation, and finally, type of starch (types A, B, and C...

  8. Fluorescent-magnetic Janus particles prepared via seed emulsion polymerization.

    Science.gov (United States)

    Kaewsaneha, Chariya; Bitar, Ahmad; Tangboriboonrat, Pramuan; Polpanich, Duangporn; Elaissari, Abdelhamid

    2014-06-15

    Anisotropic polymeric colloidal or Janus particles possessing simultaneous magnetic and fluorescent properties were successfully prepared via the swelling-diffusion or the in situ emulsion polymerization method. In the swelling-diffusion process, magnetic emulsions (an organic ferrofluid dispersed in aqueous medium) were synthesized and used for seeds of submicron magnetic Janus particles. After swelling the anisotropic particles obtained by 1-pyrene-carboxaldehyde fluorescent dye dissolved in tetrahydrofuran, well-defined fluorescent-magnetic Janus particles were produced. In the in situ emulsion polymerization, styrene monomer mixed with fluorescent dye monomers, i.e., 1-pyrenylmethyl methacrylate (PyMMA) or fluorescein dimethacrylate (FDMA), and an oil-soluble initiator (2,2'-azobis(2-isobutyronitrile)) were emulsified in the presence of magnetic seed emulsions. The confocal microscopic images showed the fluorescent-magnetic Janus particles with high fluorescent intensity when a fluorescent crosslinker monomer FDMA was employed. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Polymeric Biomaterials: Diverse Functions Enabled by Advances in Macromolecular Chemistry.

    Science.gov (United States)

    Liang, Yingkai; Li, Linqing; Scott, Rebecca A; Kiick, Kristi L

    2017-01-24

    Biomaterials have been extensively used to leverage beneficial outcomes in various therapeutic applications, such as providing spatial and temporal control over the release of therapeutic agents in drug delivery as well as engineering functional tissues and promoting the healing process in tissue engineering and regenerative medicine. This perspective presents important milestones in the development of polymeric biomaterials with defined structures and properties. Contemporary studies of biomaterial design have been reviewed with focus on constructing materials with controlled structure, dynamic functionality, and biological complexity. Examples of these polymeric biomaterials enabled by advanced synthetic methodologies, dynamic chemistry/assembly strategies, and modulated cell-material interactions have been highlighted. As the field of polymeric biomaterials continues to evolve with increased sophistication, current challenges and future directions for the design and translation of these materials are also summarized.

  10. Preparation of polymeric superhydrophobic surfaces and analysis of their wettability

    Science.gov (United States)

    Zhuang, Jian; Huang, Manling; Zhang, Yajun; Wu, Daming; Kuang, Tairong; Xu, Hong; Zhang, Xiaoxu

    2015-10-01

    In this paper, we presented three simple, facile and low-cost manufacturing methods—template method, nanoparticle filling method and extrusion stamping forming method—to fabricate the polymeric superhydrophobic surfaces. The stainless steel wire mesh as the template and glass beads was investigated in this study for the first time and low-cost hollow glass beads were rarely used as particles for fabricating the superhydrophobic surface. The water contact angle measurement of polymeric surfaces was used to investigate the effect of mesh count, glass beads and PTFE on fabricating polymeric superhydrophobic surface. It was found that the mesh count significantly affected the hydrophobicity of polymer surface in template method. The addition of glass beads improved the hydrophobicity by nanoparticle filling method. The addition of PTFE was of importance to fabricate the superhydrophobic surface by extrusion stamping forming method. The surface microstructure was also observed by scanning electron microscope.

  11. Optimization of Microencapsulation Process for Self-Healing Polymeric Material

    International Nuclear Information System (INIS)

    Then, S.; Neon, G.S.; Noor Hayaty Abu Kasim

    2011-01-01

    A series of poly(urea-formaldehyde) (PUF) microcapsules filled with dicyclopentadiene (DCPD) was successfully prepared by in situ polymerization. The effect of diverse process parameters and ingredients on the morphology of the microcapsules was observed by SEM, optical microscopy (OM) and digital microscopy. Different techniques for the characterization of the chemical structure and the core content were considered such as FT-IR and 1 H-NMR as well as the characterization of thermal properties by DSC. High yields of free flowing powder of spherical microcapsules were produced. The synthesized microcapsules can be incorporated into another polymeric host material. In the event the host material cracks due to excessive stress or strong impact, the microcapsules would rupture to release the DCPD, which could polymerize to repair the crack. (author)

  12. Synthesis of Amphiphilic Copolymwers by Atom Transfer Radical Polymerization

    DEFF Research Database (Denmark)

    Hansen, Natanya Majbritt Louie

    2007-01-01

    Fluorerede polymerer besidder en række enestående egenskaber såsom god biokom-patibilitet og lav overfladeenergi såvel som god kemisk og termisk stabilitet. Målsæt-ningen for denne afhandling var at fremstille fluorerede polymerer og copolymerer, der potentielt kunne finde anvendelse som...... egenskaber der genfindes i homopolymerer af den dominerende monomer i copolymeren. Som indikation af de nye materialers mulige vekselvirkning med omgivelserne udførtes omfattende studier af kontaktvinkler. Film fremstillet af de fluorerede copolymerer og polymerer udviste øget hydrofobicitet (vandafvisning...... luftfugtighed fra copolymerer af 3FM og MMA, hvilket resulterede i meget hydrofobe overflader med statiske kontaktvinkler for vand på op til 144°....

  13. The influence of chemical characteristics of precipitation on tree health in Banjica Forest (Belgrade, Serbia

    Directory of Open Access Journals (Sweden)

    Radovanović M.

    2012-01-01

    Full Text Available The most represented tree species in the Banjica Forest are Acer negundo, Quercus robur, Acer pseudoplatanus, Populus nigra, Fraxinus pennsylvanica, Fraxinus ornus and Robinia pseudoacacia. According to the ICP Forests combined assessment (degree of defoliation and decolorization, endangered species are Populus nigra (64.3% of heavily damaged trees, Quercus robur (45.5%, Fraxinus pennsylvanica (37.0% and Acer negundo (26.6%, while the situation is much better for Acer pseudoplatanus and Fraxinus ornus. For Robinia pseudoacacia, 83% of trees are without decolorization, however, defoliation is established. In the period from April to October 2009, the average pH of rainwater was 5.46, and 5.18 in the period from November 2009 to March 2010. The concentration of SO42- in the period from April to October 2009 amounted to an average of 24.21 mg/l, and 28.87 mg/l in the period from November 2009 to March 2010. The concentration of SO42- and pH values is a possible explanation for the condition of the trees. [Acknowledgments. The results are a part of the project III47007 funded by the Ministry of Education and Science of the Republic of Serbia.

  14. Kinetics of polymerization of diallyl phthalate (DAP) by gamma rays

    International Nuclear Information System (INIS)

    Divakar, D.S.; Rao, K.

    1975-01-01

    Diallyl o-phthalate (DAP) was polymerized by γ radiation from a 60 Co source and the kinetics of polymerization were studied at several dose rates and temperatures. The results show that the rate of polymerization was proportional to I 0 . 68 , where I is the radiation dose rate. The net activation energy of the polymerization reaction (E/sub p/-1/2E/sub t/) was 5.02 kcal/mole, where E/sub p/ and E/sub t/ are the activation energies for the propagation and termination steps, respectively. The radical yield G/sub R/ for DAP was measured by the loss of diphenyl picryl hydrazyl (DPPH) used as a radical scavenger. G/sub R/ in the solution after irradiation was 3.12. The ratio of the rate constants k 2 /sub p//k/sub t/ was calculated to be 4.09 x 10 -7 at 25.8 0 C and 15.0 x 10 -7 at 55.4 0 C. At room temperature, the ratio of degradative chain transfer constant to k/sub p/, i.e., k/sub u//k/sub p/ was found to be 0.065 and k/sub tr//k/sub u/ as 0.032, where k/sub tr/ is the nondegradative chain-transfer constant. Molecular weights of these polymers as determined by vapor pressure osmometry showed that the degree of polymerization was between 8 and 10. Infrared spectra of the polymers indicated that intramolecular cyclization took place during polymerization

  15. Photo stabilization of polymeric materials by photo set acrylate coatings

    Energy Technology Data Exchange (ETDEWEB)

    Decker, C. E-mail: c.decker@uha.fr; Zahouily, K

    2002-01-01

    Different types of polymeric materials have been made more resistant to photodegradation by protecting their surface with a UV-cured coating containing a HALS radical scavenger and a phenyl triazine UV absorber. The tri dimensional polymer network formed by photo polymerization of an aliphatic polyurethane-acrylate telechelic oligomer proved to be very resistant to accelerated weathering in the presence of these light stabilizers. The chemical modifications occurring upon QUV-ageing were monitored by infrared spectroscopy/ a very sensitive technique well suited for quantitative analysis at an early stage of the photodegradation.

  16. Preparing polymeric matrix composites using an aqueous slurry technique

    Science.gov (United States)

    Johnston, Norman J. (Inventor); Towell, Timothy W. (Inventor)

    1993-01-01

    An aqueous process was developed to prepare a consolidated composite laminate from an aqueous slurry. An aqueous poly(amic acid) surfactant solution was prepared by dissolving a poly(amic acid) powder in an aqueous ammonia solution. A polymeric powder was added to this solution to form a slurry. The slurry was deposited on carbon fiber to form a prepreg which was dried and stacked to form a composite laminate. The composite laminate was consolidated using pressure and was heated to form the polymeric matrix. The resulting composite laminate exhibited high fracture toughness and excellent consolidation.

  17. Production of radiation crosslinked polymeric compositions using diacetylenes

    International Nuclear Information System (INIS)

    Patel, G.N.

    1979-01-01

    Crosslinked polymeric compositions, useful as electrical insulators, heat shrinkable packaging, and lightweight foam plastics, are described. The crosslinked polymeric compositions are produced by admixing a diacetylene monomer, oligomer, polymer or mixture thereof, wherein the monomer has the formula, RNHCO-O-CH 2 -C==C-C==C-CH- 2 -O-OCNHR' in which R and R' are the same or different and are alkyl containing 1 to 20 carbon atoms, with a thermoplastic crosslinkable polymer and then subjecting the resulting mixture to actinic radiation

  18. Nanoencapsulation of blocked isocyanates through aqueous emulsion polymerization

    Directory of Open Access Journals (Sweden)

    2008-05-01

    Full Text Available Blocked isocyanates were successfully encapsulated into polystyrene and hydroxyl and amine functionalized polymeric nanospheres via emulsion polymerization. The nanocapsules were characterized via Fourier transform infrared spectroscopy, differential scanning calorimetry and transmission electronic microscopy. The blocked isocyanates generated free isocyanate functionality upon thermal annealing of nanocapsules. This research establishes a novel encapsulating method for release and retention of free isocyanates in aqueous media. These nanocapsules can provide active isocyanates in coatings and adhesive applications, and represent a novel application of nanoencapsulated materials for controlled or delayed active material utilization.

  19. Studies on the polymerization of acrolein oxime, 13

    International Nuclear Information System (INIS)

    Ota, Tadatoshi; Mori, Yoshikazu; Tamai, Harumi; Masuda, Seizo; Tanaka, Masami.

    1980-01-01

    The radiation-induced polymerization of acrolein oxime was carried out at temperatures ranging from room temperature to -78 0 C, and the resulting low molecular products were analyzed by gas chromatography-mass spectrometry. Acetaldoxime, propionaldoxime, propenylhydroxylamines, dioximes etc. were obtained. Initial processes of the polymerization are discussed on the basis of these reaction products. The present work offers further corroborating evidence for the already-described postulation that an anionic mechanism is operative above room temperature, and a cationic mechanism is predominant below -23 0 C. (author)

  20. Immobilization of yeast cells by radiation-induced polymerization

    International Nuclear Information System (INIS)

    Fujimura, T.; Kaetsu, I.

    1982-01-01

    Radiation-induced polymerization method was applied to the immobilization of yeast cells. The effects of irradiation, cooling and monomer, which are neccessary for polymerization, were recovered completely by subsequent aerobical incubation of yeast cells. The ethanol productive in immobilized yeast cells increased with the increase of aerobical incubation period. The growth of yeast cells in immobilized yeast cells was indicated. The maximum ethanol productivity in immobilized yeast cell system was around three times as much as that in free yeast cell system. (orig.)

  1. Polymeric Gas-Separation Membranes for Petroleum Refining

    Directory of Open Access Journals (Sweden)

    Yousef Alqaheem

    2017-01-01

    Full Text Available Polymeric gas-separation membranes were commercialized 30 years ago. The interest on these systems is increasing because of the simplicity of concept and low-energy consumption. In the refinery, gas separation is needed in many processes such as natural gas treatment, carbon dioxide capture, hydrogen purification, and hydrocarbons separations. In these processes, the membranes have proven to be a potential candidate to replace the current conventional methods of amine scrubbing, pressure swing adsorption, and cryogenic distillation. In this paper, applications of polymeric membranes in the refinery are discussed by reviewing current materials and commercialized units. Economical evaluation of these membranes in comparison to traditional processes is also indicated.

  2. Living atom transfer radical polymerization of 4-acetoxystyrene

    DEFF Research Database (Denmark)

    Gao, Bo; Chen, Xianyi; Ivan, Bela

    1997-01-01

    Living atom transfer radical polymerization (ATRP) of 4-acetoxystyrene (1), a protected 4-vinylphenol, leading to poly(4-acetoxystyrene) with well-defined molecular weight and narrow molecular weight distribution was carried out in bulk with a,a'-dibromoxylene(2)/CuBr/2,2-bipyridine(bpy) as initi......Living atom transfer radical polymerization (ATRP) of 4-acetoxystyrene (1), a protected 4-vinylphenol, leading to poly(4-acetoxystyrene) with well-defined molecular weight and narrow molecular weight distribution was carried out in bulk with a,a'-dibromoxylene(2)/CuBr/2,2-bipyridine...

  3. Spin-crossover behavior of polymeric iron(III) complexes

    International Nuclear Information System (INIS)

    Maeda, Yonezo; Miyamoto, Makoto; Takashima, Yoshimasa; Oshio, Hiroaki

    1989-01-01

    Polymeric spin-crossover iron(III) complexes possessing poly(4-vinylpyridine), poly(N-vinylimidazole) or poly(octylmethacrylate-co-4-vinylpyridine) as ligand are prepared. In this experience enriched 57 Fe was used to get strong Moessbauer absorption. The enriched behavior of the complexes were examined by magnetic susceptibilities measurement, and Moessbauer and esr spectroscopies. Some of them show spin-state behavior over a wide range of temperature. Some of them show rapid spin-state interexchange compared to the Moessbauer time scale and others not. Spin-crossover behavior of polymeric complexes is characterized of wide spin-state transition temperature range

  4. On the sedimentation velocity of spheres in a polymeric liquid

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Hassager, Ole

    1996-01-01

    A Lagrangian finite element method is used to simulate the transient sedimentation of spheres in polymeric liquids. The liquid is described by an integral constitutive equation of the Rivlin-Sawyers type. The simulations show a marked increase in the drag, which is apparently related to the elong......A Lagrangian finite element method is used to simulate the transient sedimentation of spheres in polymeric liquids. The liquid is described by an integral constitutive equation of the Rivlin-Sawyers type. The simulations show a marked increase in the drag, which is apparently related...

  5. Optical Fiber Tweezers Fabricated by Guided Wave Photo-Polymerization

    Directory of Open Access Journals (Sweden)

    Rita S. Rodrigues Ribeiro

    2015-06-01

    Full Text Available In this work the use of guided wave photo-polymerization for the fabrication of novel polymeric micro tips for optical trapping is demonstrated. It is shown that the selective excitation of linear polarized modes, during the fabrication process, has a direct impact on the shape of the resulting micro structures. Tips are fabricated with modes LP02 and LP21 and their shapes and output intensity distribution are compared. The application of the micro structures as optical tweezers is demonstrated with the manipulation of yeast cells.

  6. Polymeric compositions incorporating polyethylene glycol as a phase change material

    Science.gov (United States)

    Salyer, Ival O.; Griffen, Charles W.

    1989-01-01

    A polymeric composition comprising a polymeric material and polyethylene glycol or end-capped polyethylene glycol as a phase change material, said polyethylene glycol and said end-capped polyethylene glycol having a molecular weight greater than about 400 and a heat of fusion greater than about 30 cal/g; the composition is useful in making molded and/or coated materials such as flooring, tiles, wall panels and the like; paints containing polyethylene glycols or end-capped polyethylene glycols are also disclosed.

  7. Surface Hardness of Resin Cement Polymerized under Different Ceramic Materials

    OpenAIRE

    Kesrak, Pimmada; Leevailoj, Chalermpol

    2012-01-01

    Objectives. To evaluate the surface hardness of two light-cured resin cements polymerized under different ceramic discs. Methods. 40 experimental groups of 2 light-cured resin cement specimens (Variolink Veneer and NX3) were prepared and polymerized under 5 different ceramic discs (IPS e.max Press HT, LT, MO, HO, and Cercon) of 4 thicknesses (0.5, 1.0, 1.5, and 2.0 mm), Those directly activated of both resin cements were used as control. After light activation and 3 7 ∘ C storage in an incuba...

  8. Organometallic-Mediated Radical Polymerization of Vinylidene Fluoride.

    Science.gov (United States)

    Banerjee, Sanjib; Ladmiral, Vincent; Debuigne, Antoine; Detrembleur, Christophe; Poli, Rinaldo; Améduri, Bruno

    2018-03-05

    An unprecedented level of control for the radical polymerization of vinylidene fluoride (VDF), yielding well-defined PVDF (at least up to 14 500 g mol -1 ) with low dispersity (≤1.32), was achieved using organometallic-mediated radical polymerization (OMRP) with an organocobalt compound as initiator. The high chain-end fidelity was demonstrated by the synthesis of PVDF- and PVAc-containing di-and triblock copolymers. DFT calculations rationalize the efficient reactivation of both head and tail chain end dormant species. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Synthesis of Well-Defined Polybenzamide-block-Polystyrene by Combination of Chain-Growth Condensation Polymerization and RAFT Polymerization.

    Science.gov (United States)

    Masukawa, Tomohiro; Yokoyama, Akihiro; Yokozawa, Tsutomu

    2009-08-18

    Well-defined diblock copolymers composed of poly(N-octylbenzamide) and polystyrene were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene with a polyamide chain transfer agent (CTA) prepared via chain-growth condensation polymerization. Synthesis of a dithioester-type macro-CTA possessing the polyamide segment as an activating group was unsatisfactory due to side reactions and incomplete introduction of the benzyl dithiocarbonyl unit. On the other hand, a dithiobenzoate-CTA containing poly(N-octylbenzamide) as a radical leaving group was easily synthesized, and the RAFT polymerization of styrene with this CTA afforded poly(N-octylbenzamide)-block-polystyrene with controlled molecular weight and narrow polydispersity. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Organo-Lewis acid as cocatalyst for cationic homogenous metallocene Ziegler-Natta olefin polymerizations

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Chicago, IL)

    2000-01-01

    The synthesis of the organo-Lewis acid perfluorobiphenylborane (PBB) and the activation of metallocenes for the formation of a variety of highly active homogeneous Ziegler-Natta metallocene olefin polymerization, copolymerization and ring-opening polymerization catalysts is described.

  11. Comparison of techniques for the determination of conversion during suspension polymerization reactions

    Directory of Open Access Journals (Sweden)

    J. C. Santos

    2008-06-01

    Full Text Available The determination of conversion during suspension polymerization reactions is not an easy task due to the heterogeneity of the reaction medium and the tendency of particles to agglomerate rapidly when stirring is stopped. Usually, bulk polymerization in ampoules is employed to study the kinetics of suspension polymerization reactions. In this work, a comparison of different techniques for the determination of conversion during suspension polymerization reactions is presented. Results showed a good agreement between the conversion obtained by gravimetry during styrene suspension polymerization and on-line conversion monitoring data using fiber-optic based Raman Spectroscopy. Nevertheless, the polymerization rate of styrene bulk polymerization carried out in ampoules was higher than the real reaction rate of styrene suspension polymerization due to slightly higher reaction temperatures. Simulation results using the experimental temperature data in a mathematical model confirmed these results.

  12. Studies of Olefin Dimerization, Oligomerization, and Polymerization Catalyzed by Cationic (alpha-Diimine)Ni(II) Complexes

    National Research Council Canada - National Science Library

    Svejda, Steven

    1999-01-01

    .... The development of cationic (alpha-diimine)nickel(II) and palladium(II) complexes which catalyze the polymerization of both ethylene and alpha-olefins to high polymers represents a major advance in the field of olefin polymerization catalysis...

  13. Tribology of polymeric nanocomposites friction and wear of bulk materials and coatings

    CERN Document Server

    Friedrich, Klaus

    2013-01-01

    Tribology of Polymeric Nanocomposites provides a comprehensive description of polymeric nanocomposites, both as bulk materials and as thin surface coatings, and provides rare, focused coverage of their tribological behavior and potential use in tribological applications. Providing engineers and designers with the preparation techniques, friction and wear mechanisms, property information and evaluation methodology needed to select the right polymeric nanocomposites for the job, this unique book also includes valuable real-world examples of polymeric nanocomposites in a

  14. The Effect of Environmental pH on Polymeric Transfection Efficiency

    OpenAIRE

    Kang, Han Chang; Samsonova, Olga; Kang, Sun-Woong; Bae, You Han

    2011-01-01

    Although polymers, polyplexes, and cells are exposed to various extracellular and intracellular pH environments during polyplex preparation and polymeric transfection, the impact of environmental pH on polymeric transfection has not yet been investigated. This study aims to understand the influence of environmental pH on polymeric transfection by modulating the pH of the transfection medium or the culture medium. Changes in the extracellular pH affected polymeric transfection by way of comple...

  15. Direct Writing of Photonic Structures by Two-Photon Polymerization

    Directory of Open Access Journals (Sweden)

    Li Yan

    2013-11-01

    Full Text Available Single-mode dielectric-loaded surface plasmon-polariton nanowaveguides with strong mode confinement at excitation wavelength of 830 nm and high-Q polymer whispering gallery mode microcavities with surface roughness less than 12 nm have been directly written by two-photon polymerization, which pave the way to fabricate 3D plasmonic photonic structures by direct laser writing.

  16. Novel Hybrid Polymeric and Inorganic Structures for Applications in Nanobiotechnology

    OpenAIRE

    Valdeperez Toledo, Daniel; Parak, Wolfgang J. (Prof. Dr.)

    2017-01-01

    This cumulative doctoral dissertation deals with the use of diverse polymers in different applications within nanoscience. The synthesis and characterization of several nano and microstructures is also explained, focusing on the later surface modification via the use of different polymers. Polymers are chemical compounds formed by the combination of several repeating structural units (monomers) in a process called polymerization. ...

  17. Theory of Phase Separation in a Polydisperse Polymerizing Mixture

    Science.gov (United States)

    Taylor, Philip; Kraig, Robert

    2000-03-01

    Theoretical studies of the process of phase separation in a polymerizing mixture frequently start by combining some established formalisms. The Flory-Huggins theory gives an expression for the free energy of a polymer in solution, while the Cahn-Hilliard theory gives a means with which to follow the time development of the system and to predict the length scale characterizing the resulting heterogeneous structure. A weakness of this approach is that Flory-Huggins theory describes an essentially monodisperse system, in which all polymer molecules are assumed to have the same molecular weight. We have developed a more powerful formalism, in which the polydispersity is taken into account. The basic ingredients of this theory are the partial differential equations that describe the local concentrations of the solvent and of the various monomers and oligomers that constitute the polymerizing system. Of these, the simplest is the continuity equation that describes the diffusion of solvent within a polymerizing matrix. This requires a description of the rate of movement of solvent and of each type of oligomer in a concentration gradient of each constituent. The more difficult task is the formulation and solution of the set of equations (in principle an infinite set) that describe the polymerization process, and hence the time rate of variation of the concentration of each constituent.

  18. Polymer-clay nanocomposites obtained by solution polymerization ...

    Indian Academy of Sciences (India)

    Abstract. Polymer-clay nanocomposites were synthesized by solution polymerization method using advanced functionalized clay and vinyl benzyl trimethyl ammonium chloride as monomer. First stage con- sisted in the silylation of a commercial organo-modified clay-Cl 20A using alkoxysilanes with different chain lengths.

  19. Rapid mixing chemical oxidative polymerization: an easy route to ...

    Indian Academy of Sciences (India)

    Administrator

    bon nanomaterial suspensions (Gedela et al 2012); here, the problems of poor solvability and/or dispersion of the constituent materials in the solvents used in synthesis protocols can be overcome. In this study, an easy method. (in situ chemical oxidative polymerization) to synthesize small diameter carbon nanotubes ...

  20. Preparation of polymeric aluminium ferric chloride from bauxite tailings

    Directory of Open Access Journals (Sweden)

    Ma D.

    2013-01-01

    Full Text Available Bauxite tailings are the main solid wastes in the ore dressing process. The Al2O3 and Fe2O3 contents in bauxite tailings can reach 50% and 13% respectively. The present study proposed a feasible method to use bauxite tailings to prepare polymeric aluminium ferric chloride (PAFC, a new composite inorganic polymer for water purification. Bauxite tailings roasted reacting with hydrochloric acid under air, pickle liquor which mainly contains Fe3+, Al3+ was generated, then calcium aluminate was used to adjust pH value and the basicity of the pickle liquor, the PAFC was subsequently prepared after the polymerization process. The optimal synthesizing parameters for the preparation of PAFC obtained were as follows: the concentration of hydrochloric acid of 24 wt%, ratio of hydrochloric acid to bauxite tailings of 6:1, temperature of 90ºC, leaching time of 2.5 hours, ration of pickle liquor to calcium aluminate of 12:1, polymerization temperature of 90ºC and polymerization time of about 3 hours. The basicity of PAFC was higher than 68%, the sum concentration of Al2O3 and Fe2O3 was beyond 12.5%. The results of flocculation tests indicate that the PAFC has a better performance of removing the turbidity of wastewater compared to PAC, and PAFC prepared by bauxite tailings is a kind of high quality flocculants.

  1. Structural Analysis of Ciprofloxacin-Carbopol Polymeric Composites ...

    African Journals Online (AJOL)

    Purpose: To evaluate physicochemical changes in ciprofloxacin following incorporation in Carbopol polymeric composites. Methods: The ciprofloxacin and Carbopol were mixed in water in a drug:polymer ratio of 1:5 (w/w) and homogenized to produce uniform composites. X-ray powder diffraction analysis of the pure ...

  2. Influence of dielectric constant of polymerization medium on ...

    Indian Academy of Sciences (India)

    Polyaniline (PANI) was synthesized by the oxidation of aniline hydrochloride in the presence of ammonium persulphate and hydrochloric acid. The polymerization reaction was carried out in several batches in different solvent media by changing the volume ratio of ,-dimethyl formamide (DMF) and water as binary solvent ...

  3. Curcumin-bortezomib loaded polymeric nanoparticles for synergistic cancer therapy

    Czech Academy of Sciences Publication Activity Database

    Medel, S.; Syrová, Z.; Kováčik, L.; Hrdý, J.; Hornacek, M.; Jäger, Eliezer; Hrubý, Martin; Lund, R.; Cmarko, D.; Štěpánek, Petr; Raška, I.; Nyström, B.

    2017-01-01

    Roč. 93, August (2017), s. 116-131 ISSN 0014-3057 R&D Projects: GA MŠk(CZ) 7F14009 Institutional support: RVO:61389013 Keywords : polymeric nanoparticles * light scattering * flow cytometry Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 3.531, year: 2016

  4. Novel Polymeric Prodrugs of Valproic Acid as Anti- Epilepsy Drugs ...

    African Journals Online (AJOL)

    The release of VPA from polymeric prodrugs was studied using cellophane membrane dialysis bags containing aqueous buffer solutions (pH 1, 7 and 10) at 37 oC. The quantity of released drug was detected by ultraviolet (UV) spectroscopy. Results: 1H-NMR and elemental analyses data for calculating mole composition of ...

  5. Polymeric Systems of Antimicrobial Peptides—Strategies and Potential Applications

    Directory of Open Access Journals (Sweden)

    Ewa Olędzka

    2013-11-01

    Full Text Available The past decade has seen growing interest in the investigation of peptides with antimicrobial activity (AMPs. One approach utilized in infection control is incorporation of antimicrobial agents conjugated with the polymers. This review presents the recent developments on polymeric AMP carriers and their potential applications in the biomedical and pharmaceutical fields.

  6. 21 CFR 177.2250 - Filters, microporous polymeric.

    Science.gov (United States)

    2010-04-01

    ... directions for a pre-use treatment, consisting of washing with a minimum of 2 gallons of potable water at a... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Filters, microporous polymeric. 177.2250 Section 177.2250 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  7. Epithelial-microbial crosstalk in polymeric Ig receptor deficient mice

    NARCIS (Netherlands)

    Reikvam, D.H.; Derrien, M.M.N.; Islam, R.; Erofeev, A.; Grcic, V.; Sandvik, A.; Gaustad, P.; Meza-Zepeda, L.A.; Jahnsen, F.L.; Smidt, H.; Johansen, F.E.

    2012-01-01

    Innate and adaptive mucosal defense mechanisms ensure a homeostatic relationship with the large and complex mutualistic gut microbiota. Dimeric IgA and pentameric IgM are transported across the intestinal epithelium via the epithelial polymeric Ig receptor (pIgR) and provide a significant portion of

  8. Synthesis of monomeric and polymeric alkali and alkaline earth ...

    Indian Academy of Sciences (India)

    5, September 2014, pp. 1463–1475. c Indian Academy of Sciences. Synthesis of monomeric and polymeric alkali and alkaline earth metal complexes using a phosphinoselenoic amide ligand in metal coordination sphere. JAYEETA BHATTACHARJEE, RAVI K KOTTALANKA, HARINATH ADIMULAM and TARUN K PANDA.

  9. Evaluation of Electrical and Thermal Conductivity of Polymeric ...

    African Journals Online (AJOL)

    PROF HORSFALL

    ABSTRACT: This work being gingered by the big menace being posed on our environment by polymeric waste and it's rechanneling involved the studying of the electrical and thermal conductivities of the polymers PP, PE, PS and nylon66 doped with charcoal and graphite. Five grams of each polymer was mixed with ...

  10. Evaluation of electrical and thermal conductivity of polymeric wastes ...

    African Journals Online (AJOL)

    This work being gingered by the big menace being posed on our environment by polymeric waste and it's rechanneling involved the studying of the electrical and thermal conductivities of the polymers PP, PE, PS and nylon66 doped with charcoal and graphite. Five grams of each polymer was mixed with varying ...

  11. Polyethylene-waste tire dust composites via in situ polymerization

    International Nuclear Information System (INIS)

    Reyes A, Y. K.; Narro C, R. I.; Ramos A, M. E.; Neira V, M. G.; Diaz E, J.; Enriquez M, F.; Valencia L, L. A.; Saade C, H.; Diaz de L, R.

    2014-01-01

    Polyethylene/waste tire dust (WTD) composites were obtained by an in situ polymerization technique. The surface of the WTD was modified with deposition of polyethylene by using plasma polymerization. Ethylene polymerization was carried out using bis(cyclopentadienyl) titanium dichloride (Cp 2 TiCl 2 ) as homogeneous metallocenes catalyst, while diethylaluminum chloride (DEAC), ethyl aluminum sesquichloride (EASC) and methyl alumino xane (Mao) were used as co-catalysts at two different [Al]/[Ti] molar ratio. The main characteristics of the obtained polyethylenes were determined by size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry and wide-angle X-ray diffraction. The results showed that by using EASC and Mao the highest catalytic activities were presented at a [Al]/[Ti] molar ratio of 9.17 and 18.33 respectively. Even though it was possible to obtain polyethylene using WTD (modified or unmodified) the catalytic activity was lower than in the case in which no WTD was added in ethylene polymerization. Scanning transmission electronic microscopy images evidenced that the original morphology of the polyethylenes was not modified by the presence of WTD. (Author)

  12. Polyethylene-waste tire dust composites via in situ polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Reyes A, Y. K.; Narro C, R. I.; Ramos A, M. E. [Universidad Autonoma de Coahuila, Facultad de Ciencias Quimicas, Blvd. Venustiano Carranza s/n, 25280 Saltillo, Coahuila (Mexico); Neira V, M. G.; Diaz E, J.; Enriquez M, F.; Valencia L, L. A.; Saade C, H.; Diaz de L, R., E-mail: ramon.diazdeleon@ciqa.edu.mx [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna Hermosillo No. 40, Col. San Jose de los Cerritos, 25293 Saltillo, Coahuila (Mexico)

    2014-10-01

    Polyethylene/waste tire dust (WTD) composites were obtained by an in situ polymerization technique. The surface of the WTD was modified with deposition of polyethylene by using plasma polymerization. Ethylene polymerization was carried out using bis(cyclopentadienyl) titanium dichloride (Cp{sub 2}TiCl{sub 2}) as homogeneous metallocenes catalyst, while diethylaluminum chloride (DEAC), ethyl aluminum sesquichloride (EASC) and methyl alumino xane (Mao) were used as co-catalysts at two different [Al]/[Ti] molar ratio. The main characteristics of the obtained polyethylenes were determined by size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry and wide-angle X-ray diffraction. The results showed that by using EASC and Mao the highest catalytic activities were presented at a [Al]/[Ti] molar ratio of 9.17 and 18.33 respectively. Even though it was possible to obtain polyethylene using WTD (modified or unmodified) the catalytic activity was lower than in the case in which no WTD was added in ethylene polymerization. Scanning transmission electronic microscopy images evidenced that the original morphology of the polyethylenes was not modified by the presence of WTD. (Author)

  13. Oxidative polymerization of anilinium 5-sulfosalicylate with peroxydisulfate in water

    Czech Academy of Sciences Publication Activity Database

    Marjanovic, B.; Juranic, I.; Mentus, S.; Ciric-Marjanovic, G.; Holler, Petr

    2010-01-01

    Roč. 64, č. 6 (2010), s. 783-790 ISSN 0366-6352 R&D Projects: GA AV ČR IAA400500905 Institutional research plan: CEZ:AV0Z40500505 Keywords : anilinium 5-sulfosalicylate * peroxydisulfate * oxidative polymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.754, year: 2010

  14. Space charge accumulation in polymeric high voltage DC cable systems

    NARCIS (Netherlands)

    Bodega, R.

    2006-01-01

    One of the intrinsic properties of the polymeric high voltage (HV) direct current (DC) cable insulation is the accumulation of electrostatic charges. Accumulated charges distort the initial Laplacian distribution of the electric field, leading to a local field enhancement that may cause insulation

  15. Assessment of polymerization contraction stress of three composite resins

    NARCIS (Netherlands)

    Cadenaro, M.; Biasotto, M.; Scuor, N.; Breschi, L.; Davidson, C.L.; Di Lenarda, R.

    2008-01-01

    Objectives: The purpose of this study was to measure the development of contraction stress of three composite resin restorative materials during photo-polymerization: a micro-hybrid composite (Filtek Z250, 3M ESPE, St. Paul, MN, USA); a nano-filled composite (Filtek Supreme, 3M ESPE, St. Paul, MN,

  16. Modeling the chemistry of plasma polymerization using mass spectrometry.

    Science.gov (United States)

    Ihrig, D F; Stockhaus, J; Scheide, F; Winkelhake, Oliver; Streuber, Oliver

    2003-04-01

    The goal of the project is a solvent free painting shop. The environmental technologies laboratory is developing processes of plasma etching and polymerization. Polymerized thin films are first-order corrosion protection and primer for painting. Using pure acetylene we get very nice thin films which were not bonded very well. By using air as bulk gas it is possible to polymerize, in an acetylene plasma, well bonded thin films which are stable first-order corrosion protections and good primers. UV/Vis spectroscopy shows nitrogen oxide radicals in the emission spectra of pure nitrogen and air. But nitrogen oxide is fully suppressed in the presence of acetylene. IR spectroscopy shows only C=O, CH(2) and CH(3) groups but no nitrogen species. With the aid of UV/Vis spectra and the chemistry of ozone formation it is possible to define reactive traps and steps, molecule depletion and processes of proton scavenging and proton loss. Using a numerical model it is possible to evaluate these processes and to calculate theoretical mass spectra. Adjustment of theoretical mass spectra to real measurements leads to specific channels of polymerization which are driven by radicals especially the acetyl radical. The estimated theoretical mass spectra show the specific channels of these chemical processes. It is possible to quantify these channels. This quantification represents the mass flow through this chemical system. With respect to these chemical processes it is possible to have an idea of pollutant production processes.

  17. Biological in situ characterization of polymeric microbubble contrast agents

    NARCIS (Netherlands)

    Wan, Sha; Egri, Gabriella; Oddo, Letizia; Cerroni, Barbara; Dähne, Lars; Paradossi, Gaio; Salvati, Anna; Lynch, Iseult; Dawson, Kenneth A; Monopoli, Marco P

    Polymeric microbubbles (MBs) are gas filled particles composed of a thin stabilized polymer shell that have been recently developed as valid contrast agents for the combined use of ultrasonography (US), magnetic resonance imaging (MRI) and single photon emission computer tomography (SPECT) imaging.

  18. In-situ polymerized polyaniline films 3. Film formation

    Czech Academy of Sciences Publication Activity Database

    Sapurina, I.; Riede, A.; Stejskal, Jaroslav

    2001-01-01

    Roč. 123, č. 3 (2001), s. 503-507 ISSN 0379-6779 R&D Projects: GA AV ČR IAA4050907; GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : polyaniline * oxidative polymerization * thin films Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.158, year: 2001

  19. Characterization of Plasma Polymerized Hexamethyldisiloxane Films Prepared by Arc Discharge

    NARCIS (Netherlands)

    Lazauskas, A.; Baltrusaitis, Jonas; Grigaliunas, V.; Jucius, D; Guobiene, A.; Prosycevas, I.; Narmontas, P.

    2014-01-01

    Herein, we present a simple method for fabricating plasma polymerized hexamethyldisiloxane films (pp-HMDSO) possessing superhydrophobic characteristics via arc discharge. The pp-HMDSO films were deposited on a soda–lime–silica float glass using HMDSO monomer vapor as a precursor. A detailed surface

  20. Polymeric Nanosuspensions for Enhanced Dissolution of Water Insoluble Drugs

    OpenAIRE

    Yadollahi, Roya; Vasilev, Krasimir; Prestidge, Clive A.; Simovic, Spomenka

    2013-01-01

    The aim of the present research is to formulate and evaluate polymeric nanosuspensions containing three model water insoluble drugs, nifedipine (NIF), carbamazepine (CBZ), and ibuprofen (IBU) with various physicochemical properties. The nanosuspensions were prepared from hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP) by a cosolvent technique with polyethylene glycol (PEG-300) and water as the cosolvents. Physicochemical and morphological characteristics of the nanosuspens...

  1. Poly(N,N-diethylacrylamide) microspheres by dispersion polymerization

    Czech Academy of Sciences Publication Activity Database

    Šponarová, Daniela; Horák, Daniel

    2008-01-01

    Roč. 46, č. 18 (2008), s. 6263-6271 ISSN 0887-624X R&D Projects: GA AV ČR KAN200200651; GA AV ČR KAN201110651 Institutional research plan: CEZ:AV0Z40500505 Keywords : colloids * crosslinking * dispersion polymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.821, year: 2008

  2. Controlled free radical polymerization of vinyl acetate with cobalt ...

    Indian Academy of Sciences (India)

    C, the colour-free reaction without solid catalyst impurity was 95% complete within a few hours. The high molecular weight of polyvinyl acetate (PVAc) with its relatively low molecular distribution without unreacted monomer provided a new method in microprocessing of the controlled radical polymerization of vinyl acetate in ...

  3. Polymerization behavior of butyl bis(hydroxymethyl)phosphine oxide ...

    Indian Academy of Sciences (India)

    lenovo

    Polymerization behavior of butyl bis(hydroxymethyl)phosphine oxide: Phosphorus containing polyethers for. Li‒ion conductivities. Heeralal Vignesh Babu, Billakanti Srinivas and Krishnamurthi Muralidharan*. School of Chemistry, University of Hyderabad, Hyderabad - 500046, India. Table of Contents. TGA plots of SPE2.

  4. Shear-induced transitions in a ternary polymeric system

    NARCIS (Netherlands)

    Zvelindovsky, AV; Sevink, GJA; Fraaije, JGEM

    The first three-dimensional simulation of shear-induced phase transitions in a polymeric system has been performed. The method is based on dynamic density-functional theory. The pathways between a bicontinuous phase with developing gyroid mesostructure and a lamellar/cylinder phase coexistence are

  5. Catalytic olefin polymerization with early transition metal compounds

    NARCIS (Netherlands)

    Eshuis, Johan Jan Willem

    1991-01-01

    The catalysis of organic reactions by soluble metal complexes has become a major tool in synthesis, both in the laboratory and in the chemical industry. Processes catalyzed by transition metal complexes include carbonylation, olefin polymerization, olefin addition, olefin oxidation and alkane and

  6. Sterically shielded diboron-containing metallocene olefin polymerization catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Marks, T.J.; Ja, L.; Yang, X.

    1995-09-05

    A non-coordinating anion, preferably containing a sterically shielded diboron hydride, if combined with a cyclopenta-dienyl-substituted metallocene cation component, such as a zirconocene metallocene, is a useful olefin polymerization catalyst component. The anion preferably has the formula as shown in the accompanying diagram where R is branched lower alkyl, such as t-butyl.

  7. Sterically shielded diboron-containing metallocene olefin polymerization catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Tobin J. (Evanston, IL); Ja, Li (Chicago, IL); Yang, Xinmin (Evanston, IL)

    1995-09-05

    A non-coordinating anion, preferably containing a sterically shielded diboron hydride, if combined with a cyclopenta-dienyl-substituted metallocene cation component, such as a zirconocene metallocene, is a useful olefin polymerization catalyst component. The anion preferably has the formula ##STR1## where R is branched lower alkyl, such as t-butyl.

  8. The Research on Modeling and Simulation of TFE Polymerization Process

    Directory of Open Access Journals (Sweden)

    Jing Gao Sun

    2014-01-01

    Full Text Available PTFE (polytetrafluoroethylene is the fluorinated straight-chain polymer, made by the polymerization of tetrafluoroethylene monomer; it is used widely because of its excellent performance and can be obtained by the polymerization of body, solutions, suspensions, and emulsions. But only the last two are the main ways. This research paper makes simulation based on Polymer Plus. It uses the emulsion polymerization method at background to carry out a semibatch reactor system. Upon the actual production conditions, simulation process under the steady state conditions is used to analyze the effects of the changes on operating conditions; the corresponding dynamic model is created to analyze the impact of the changes of conditions on the entire system. Moreover, the amount of APS which plays an important part in this reaction is discussed for getting the most suitable amount of initiator. Because of less research work on this job, it is so difficult to find the related data from the literature. Therefore, this research will have a great significance for the process of the tetrafluoroethylene emulsion polymerization in the future.

  9. Controlled radical polymerization of vinyl acetate in presence of ...

    Indian Academy of Sciences (India)

    tions compete with the free radical reaction. Solvent cage in the solution polymerization has been suggested to account for the reduced rate and diffusivity of the radicals, and there- fore, higher branching of the polymer (Semsarzadeh et al. 1997). The ATRP reactions of acrylates with vinyl acetate macroradicals are reported ...

  10. Propylene polymerization in a circulating slugging fluidized bed reactor

    NARCIS (Netherlands)

    van Putten, I.C.

    2004-01-01

    The work presented in this thesis is concerned with research on the riser of a circulating fluidized bed system for olefin polymerization. In the riser section, fluidization takes place in the transporting slugging mode and polymer particles are produced in the riser in a non-isothermal way.

  11. An investigation on polymeric blend mixed matrix membranes of ...

    African Journals Online (AJOL)

    Polymeric membranes have been vastly used for gas separation purposes however they have an upper-bound trade off problem which is the reason why this research work is focusing on inorganic filler added to polymer blend membranes to enhance the selectivity and permeability of the resulted membranes. Different ...

  12. Closed-cell polymeric foam for hydrogen separation and storage

    Czech Academy of Sciences Publication Activity Database

    Pientka, Zbyněk; Pokorný, P.; Bélafi-Bakó, K.

    2007-01-01

    Roč. 304, 1-2 (2007), s. 82-87 ISSN 0376-7388 R&D Projects: GA ČR GA203/06/1207 Institutional research plan: CEZ:AV0Z40500505 Keywords : polymeric foam * gas separation * hydrogen storage Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.432, year: 2007

  13. Stresses and strains under torsion of polymeric parts

    Directory of Open Access Journals (Sweden)

    Kulyk T.I.

    2016-12-01

    Full Text Available The article is devoted to the determination of stress arising during deformation of polymeric parts, namely, under torsion. Analytical methods with a graphical representation of are used in the paper. Because the elastic properties of polymeric materials do not obey Hooke's law, the use of classical methods of applied mechanics for description of such parts leads to errors in calculation results. The process of deformation of polymeric beams under torsion is analyzed. The mathematical model is evolved to describe the process of torsion of solid and hollow beams of circular cross section. The expressions for shear stress distribution along the radius of the beam and calculating the angle of twist of beam’s sections under torque are obtained, given the nature of dependence between strains and stresses for the polymeric material. Graphic dependencies are built, showing the results of calculation of shear stresses and deformations of beams at different values of torque. The mathematical model is built using a power relationship between stress and deformation of the polymer material. The results can be used for the design of structural elements of machines and appliances, building constructions, products of light industry.

  14. Fiber Drawn 2D Polymeric Photonic Crystal THz Filters

    DEFF Research Database (Denmark)

    Stecher, Matthias; Jansen, Christian; Ahmadi-Boroujeni, Mehdi

    2012-01-01

    In this paper, we report on different polymeric 2D photonic crystal filters for THz frequencies which are fabricated by a standard fiber drawing technique. The bandstop filters were simulated and designed by the generalized multipole technique (GMT). The frequency and angle dependent transmission...

  15. Polymer-clay nanocomposites prepared via in situ emulsion polymerization

    Czech Academy of Sciences Publication Activity Database

    Sedláková, Zdeňka; Pleštil, Josef; Baldrian, Josef; Šlouf, Miroslav; Holub, P.

    2009-01-01

    Roč. 63, č. 3 (2009), s. 365-384 ISSN 0170-0839 R&D Projects: GA AV ČR KAN100500651; GA MŠk ME09058 Institutional research plan: CEZ:AV0Z40500505 Keywords : organic -inorganic hybrid * organoclay * emulsion polymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.014, year: 2009

  16. Modeling lignin polymerization. Part 1: simulation model of dehydrogenation polymers.

    NARCIS (Netherlands)

    F.R.D. van Parijs (Frederik); K. Morreel; J. Ralph; W. Boerjan; R.M.H. Merks (Roeland)

    2010-01-01

    htmlabstractLignin is a heteropolymer that is thought to form in the cell wall by combinatorial radical coupling of monolignols. Here, we present a simulation model of in vitro lignin polymerization, based on the combinatorial coupling theory, which allows us to predict the reaction conditions

  17. Functional Block Copolymers via Anionic Polymerization for Electroactive Membranes

    OpenAIRE

    Schultz, Alison

    2013-01-01

           Ion-containing block copolymers blend ionic liquid properties with well-defined polymer architectures. This provides conductive materials with robust mechanical stability, efficient processability, and tunable macromolecular design. Conventional free radical polymerization and anion exchange achieved copolymers containing n-butyl acrylate and phosphonium ionic liquids. These compositions incorporated vinylbenzyl triphenyl phosphonium and vinylbenzyl tricyclohexyl phosphonium cations be...

  18. Preparation and Evaluation of Inhalable Itraconazole Chitosan Based Polymeric Micelles

    Directory of Open Access Journals (Sweden)

    Esmaeil Moazeni

    2012-12-01

    Full Text Available Background: This study evaluated the potential of chitosan based polymeric micelles as a nanocarrier system for pulmonary delivery of itraconazole (ITRA.Methods: Hydrophobically modified chitosan were synthesized by conjugation of stearic acid to the hydrophilic depolymerized chitosan. FTIR and 1HNMR were used to prove the chemical structure and physical properties of the depolymerized and the stearic acid grafted chitosan. ITRA was entrapped into the micelles and physicochemical properties of the micelles were investigated. Fluorescence spectroscopy, dynamic laser light scattering andtransmission electron microscopy were used to characterize the physicochemical properties of the prepared micelles. The in vitro pulmonary profile of polymeric micelles was studied by an air-jet nebulizer connected to a twin stage impinger.Results: The polymeric micelles prepared in this study could entrap up to 43.2±2.27 μg of ITRA per milliliter. All micelles showed mean diameter between 120–200 nm. The critical micelle concentration of the stearic acid grafted chitosan was found to be 1.58×10-2 mg/ml. The nebulization efficiency was up to 89% and the fine particle fraction (FPF varied from 38% to 47%. The micelles had enough stability to remain encapsulation of the drug during nebulization process.Conclusions: In vitro data showed that stearic acid grafted chitosan based polymeric micelles has a potential to be used as nanocarriers for delivery of itraconazole through inhalation.

  19. Redox-mediated polymerization and removal of benzidine from ...

    African Journals Online (AJOL)

    Peroxidase from Momordica charantia was highly effective, active and stable for the oxidation of benzidine from model wastewater. There was no oxidative polymerization of benzidine without any redox mediator. Various experimental parameters were standardized for the maximum oxidation of benzidine by peroxidase.

  20. Radiation-Induced Polymerization Monitored with Fluorogenic Molecular Probes

    NARCIS (Netherlands)

    Frahn, M.S.

    2003-01-01

    Each year over one billion pounds of acrylic-based polymeric products are produced world wide. Such products include windows in aircraft, lenses in eyeglasses and CD players, coatings on parquet flooring and various architectural structures such as skylights and domes. Often these products are made

  1. Kinetics and mechanism of polymerization of methyl methacrylate ...

    Indian Academy of Sciences (India)

    Unknown

    Kinetics and mechanism of polymerization of methyl methacrylate initiated by stibonium ylide. A K SRIVASTAVA and AJEY KUMAR CHAURASIA. Department of Chemistry, H B Technological Institute, Kanpur 208 002, India e-mail: akspolym@rediffmail.com. MS received 6 September 2002; revised 25 July 2003. Abstract.

  2. Novel polymeric biochips for enhanced detection of infectious diseases

    CERN Document Server

    Hosseini, Samira

    2016-01-01

    This book focuses on the creation and development of polymeric platforms (different compositions) from a specific polymer system. This system can be used as an adaptive technique for producing sensitive analytical devices, or for simple integration into existing bioanalytical tools in order to enhance the detection signal.

  3. Controlled radical polymerization of vinyl acetate in presence of ...

    Indian Academy of Sciences (India)

    Mesoporous silica; heterogeneous catalyst; specific sequences; controlled free radical polymerization; ... copolymers. CRP is a common technique for synthesis of (co)polymers with well-defined molecular parameters. (Mw/Mn), reactive end groups, composition and ... bulk copolymerization of vinyl acetate with butyl acrylate.

  4. Transparent conducting oxides on polymeric substrates by pulsed laser deposition

    NARCIS (Netherlands)

    Dekkers, Jan M.

    2007-01-01

    This thesis describes the research on thin films of transparent conducting oxides (TCOs) on polymeric substrates manufactured by pulsed laser deposition (PLD). TCOs are an indispensable part in optoelectronic applications such as displays, solar cells, light-emitting diodes, etc. At present, in many

  5. Crosslinking polymerization of tetraethylene glycol dimethacrylate under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Kaminski, K; Paluch, M; Ziolo, J [Institute of Physics, Silesian University, Uniwersytecka 4, 40-007 Katowice (Poland); Bogoslovov, R; Roland, C M [Chemistry Division, Code 6120, Naval Research Laboratory, Washington DC 20375-5342 (United States)], E-mail: kaminski@us.edu.pl

    2008-07-15

    The polymerization reaction of tetraethylene glycol dimethacrylate was induced by application of high pressure. Broadband dielectric spectroscopy was employed to investigate dielectric properties of the produced polymers. Additionally swelling experiment was performed to determine the degree of crossliniking of the polymers.

  6. Three-dimensional simulations of viscoelastic instability in polymeric filaments

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Hassager, Ole

    1999-01-01

    The three-dimensional Langrangian integral method is used to simulate the elastic end-plate instability that occurs in the rapid extension of some polymeric filaments between parallel plates. It is demonstrated that the upper convected Maxwell model describes the essential features of the instabi...

  7. Water vapor and Gas Transport through Polymeric Membranes

    NARCIS (Netherlands)

    Metz, S.J.

    2003-01-01

    Water vapor transport through polymeric materials plays an important role in a large number of applications such as: food packaging, breathable clothing, roofing membranes, diapers, and the removal of water vapor from gas streams (e.g. dehydration of natural gas or the drying of compressed air).

  8. Surface Initiated Polymerizations via e-ATRP in Pure Water

    NARCIS (Netherlands)

    Hosseiny, Seyed Schwan; van Rijn, Patrick

    2013-01-01

    Here we describe the combined process of surface modification with electrochemical atom transfer radical polymerization (e-ATRP) initiated from the surface of a modified gold-electrode in a pure aqueous solution without any additional supporting electrolyte. This approach allows for a very

  9. The pentafluorostyrene endeavours with atom transfer radical polymerization - quo vadis?

    DEFF Research Database (Denmark)

    Hvilsted, Søren

    2014-01-01

    The versatility of the atom transfer radical polymerization (ATRP) of pentafluorostyrene (FS) is comprehensively evaluated. The ATRP of a wide range of monomers derived from FS is likewise discussed with emphasis on the potential polymer applications. A large number of block and star copolymers...

  10. Hyper-cross-linked, hybrid membranes via interfacial polymerization

    NARCIS (Netherlands)

    Raaijmakers, Michiel

    2015-01-01

    Hyper-cross-linked, hybrid membranes consist of covalent networks of alternating organic and inorganic, or biological groups. This thesis reports on the preparation of such hybrid networks via interfacial polymerization. The structure-property relationships of the hybrid networks depend strongly on

  11. Effect of homopolymer in polymerization-induced microphase separation process

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jongmin; Saba, Stacey A.; Hillmyer, Marc A.; Kang, Dong-Chang; Seo, Myungeun (IBS-Korea); (KAIST); (UMMN)

    2017-09-01

    We report on the phase separation behaviors of polymerization mixtures containing a polylactide macro-chain transfer agent (PLA-CTA), styrene, divinylbenzene, hydroxyl-terminated PLA (PLA-OH), and a molecular chain transfer agent which enable the ability to tune the pore size of a cross-linked polymer monolith in a facile manner. Cross-linked monoliths were produced from the mixtures via reversible addition-fragmentation chain transfer (RAFT) polymerization and converted into cross-linked porous polymers by selective removal of PLA while retaining the parent morphology. We demonstrate that pore sizes are tunable over a wide range of length scales from the meso- to macroporous regimes by adjusting the ratio of PLA-CTA to PLA-OH in the reaction mixture which causes the phase separation mechanism to change from polymerization-induced microphase separation to polymerization-induced phase separation. The possibility of increasing porosity and inducing simultaneous micro- and macrophase separation was also realized by adjustments in the molar mass of PLA which enabled the synthesis of hierarchically meso- and macroporous polymers.

  12. Supported organometallic catalysts for hydrogenation and Olefin Polymerization

    Science.gov (United States)

    Marks, Tobin J.; Ahn, Hongsang

    2001-01-01

    Novel heterogeneous catalysts for the which hydrogenation of olefins and arenes with high conversion rates under ambient conditions and the polymerization of olefins have been developed. The catalysts are synthesized from Ziegler-type precatalysts by supporting them on sulfate-modified zirconia.

  13. Reaction Kinetics Model of Polymerization in the Absence of ...

    African Journals Online (AJOL)

    This paper is on reaction kinetics models for approximating diffuse propagation reaction fronts in one-dimensional gasless combustion type models. This study is carried out in the context of free-radical frontal polymerization (FP) via a propagating, self sustaining reacting front in the absence of material diffusion. The model ...

  14. Application of fuzzy logic in the control of polymerization reactors

    NARCIS (Netherlands)

    Roffel, B.; Chin, P.A.

    1993-01-01

    Polymer reactors are ideal candidates for the application of fuzzy control. Many polymerization reactions are difficult to model, process measurements are often only available from laboratory analysis at infrequent time intervals and trace impurities can have a marked effect on the reaction. All

  15. Mineralization-inhibiting effects of transglutaminase-crosslinked polymeric osteopontin.

    Science.gov (United States)

    Hoac, Betty; Nelea, Valentin; Jiang, Wenge; Kaartinen, Mari T; McKee, Marc D

    2017-08-01

    Osteopontin (OPN) belongs to the SIBLING family (Small, Integrin-Binding LIgand N-linked Glycoproteins) of mineral-binding matrix proteins found in bones and teeth. OPN is a well-known inhibitor of matrix mineralization, and enzymatic modification of OPN can affect this inhibitory function. In bone, OPN exists both as a monomer and as a high-molecular-weight polymer - the latter is formed by transglutaminase-mediated crosslinking of glutamine and lysine residues in OPN to create homotypic protein assemblies. OPN can be covalently crosslinked by transglutaminase 2 (TG2) and Factor XIII-A. Polymeric OPN has increased binding to collagen and promotes osteoblast adhesion, but despite these initial observations, its role in mineralization is not clear. In this study, we investigated the effect of polymerized OPN on mineralization using a hydroxyapatite crystal growth assay and mineralizing MC3T3-E1 osteoblast cultures. In the cultures, endogenous polymeric OPN was detected after mineralization occurred. In cell-free conditions, TG2 was used to crosslink bovine OPN into its polymeric form, and atomic force microscopy and dynamic light scattering revealed variably-sized, large branched aggregates ranging across hundreds of nanometers. These OPN polymers inhibited the growth of hydroxyapatite crystals in solution at concentrations similar to monomeric OPN, although the crosslinking slightly reduced its inhibitory potency. When added to MC3T3-E1 osteoblast cultures, this exogenous polymeric OPN essentially did not inhibit mineralization when given during the later mineralization stages of culture; however, cultures treated early and then continuously with polymeric OPN throughout both the matrix assembly and mineral deposition stages showed reduced mineralization. Immunoblotting of protein extracts from these continuously treated cultures revealed exogenous OPN polymers incorporated into mature matrix that had not yet mineralized. These results suggest that in bone, the

  16. Kinetics and Mechanism of Bulk Polymerization of Vinyl Chloride in a Polymerization Reactor

    Directory of Open Access Journals (Sweden)

    A. S. Ibrahim

    2015-12-01

    Full Text Available Polyvinyl chloride (PVC is the third most commonly produced polymer and is important because of its mechanical characteristics. The most common method of PVC manufacturing is the process of suspension. Although, there are several benefits associated with suspension, this study will focus on the bulk polymerization of vinyl chloride; highlight the physical and chemical properties of PVC, which can be changed through an estimation of the optimum ratio that exists between the hydrophilic and hydrophobic parts of the polymer’s surface, and propose a new mathematical model which will be helpful for the conversion of PVC into a useful form. The result will be the proposal of a new dynamic mathematical model for the three-phase structure model. All particles have been taken into account in the proposed model, which helped contribute to the reaction in gel, solid, and liquid phases, emphasizing the use of mercury (Hg as a catalyst. The proposed mathematical model considers the heat and mass transfer between the liquid, gel, and solid phases with chemical reactions that occur between the liquid and solid phases, and between the gel and solid phases. The effect of the catalyst and volumetric flow rates of vinyl chloride monomer (VCM on the system have been evaluated through the proposed mathematical model. Furthermore, the study’s experimental data have been compared with the findings of the suggested model in the context of concentration and temperature reaction. Obtained results show good agreement between the proposed mathematical model and the actual plant data.

  17. Copper-mediated controlled radical polymerization under biological conditions: SET-LRP in blood serum.

    Science.gov (United States)

    Zhang, Qiang; Li, Zaidong; Wilson, Paul; Haddleton, David M

    2013-07-28

    The polymerization of hydrophilic monomers is reported utilizing Cu(0)-mediated living radical polymerization, SET-LRP. Highly active Cu(0) is formed in situ as a result of rapid disproportionation of [Cu(I)(Me6-Tren)Br] in serum. Disproportionation and homogenous controlled radical polymerization (PDI 1.09-1.25) are performed for the first time in blood (sheep) serum.

  18. Homogeneous vs heterogeneous polymerization catalysis revealed by single-particle fluorescence microscopy.

    Science.gov (United States)

    Esfandiari, N Melody; Blum, Suzanne A

    2011-11-16

    A high-sensitivity and high-resolution single-particle fluorescence microscopy technique differentiated between homogeneous and heterogeneous metathesis polymerization catalysis by imaging the location of the early stages of polymerization. By imaging single polymers and single crystals of Grubbs II, polymerization catalysis was revealed to be solely homogeneous rather than heterogeneous or both.

  19. Anionic PPV polymerization from the sulfinyl precursor route : Block copolymer formation from sequential addition of monomers

    NARCIS (Netherlands)

    Cosemans, Inge; Vandenbergh, Joke; Voet, Vincent S. D.; Loos, Katja; Lutsen, Laurence; Vanderzande, Dirk; Junkers, Thomas

    2013-01-01

    The sulfinyl precursor route for the synthesis of poly(p-phenylene vinylene) (PPV) materials via an anionic polymerization procedure employing dedicated initiators is evaluated in depth. Reaction kinetics are investigated to gain more control over the polymerization, since polymerization proceeds to

  20. Antidepressant properties of aqueous acerate from Gladiolus ...

    African Journals Online (AJOL)

    Materials and Methods: We assessed the antidepressant properties of G. dalenii corm aqueous extract in mice, using the open field, forced swimming, and tail suspension tests. Spontaneous locomotor activity of mice given various doses of G. dalenii extract (per os) was determined in the open field, whereas immobility was ...