Science.gov

Sample records for ridley dphil dsc

  1. Sir Harold Ridley: innovator of cataract surgery.

    PubMed

    Sarwar, H; Modi, N

    2014-09-01

    Cataract surgery has evolved greatly over the years, from the ancient practice of 'couching' where the lens is dislodged, to the modern surgical techniques of today. Sir Harold Ridley's invention of the intraocular lens (IOL) has altered the approach towards cataract surgery, benefitting individuals worldwide. This has been his most notable contribution, it is therefore interesting to explore the build up to this event and gain an understanding of the issues faced by Sir Ridley. This paper explores the significant events and key developments that influenced one of the most valuable innovations in the context of cataract surgery--the intraocular lens.

  2. 77 FR 61573 - Endangered and Threatened Species; Initiation of 5-Year Review for Kemp's Ridley, Olive Ridley...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-10

    ...; Initiation of 5-Year Review for Kemp's Ridley, Olive Ridley, Leatherback, and Hawksbill Sea Turtles AGENCY... (Dermochelys coriacea), and hawksbill (Eretmochelys imbricata) sea turtles under the Endangered Species Act of..., leatherback, and hawksbill sea turtles. Public Solicitation of New Information To ensure that the...

  3. Evaluation of an unused 1952 Ridley intraocular lens.

    PubMed

    Patel, A S; Carson, D R; Patel, P H

    1999-11-01

    To evaluate an unused 1952 historic Ridley intraocular lens (IOL) brought to Bombay, India, in 1952 from an Oxford Ophthalmologic Conference in England and given to 1 of the authors during his residency. Alcon Laboratories, Fort Worth, Texas, USA. The Ridley IOL was evaluated at Alcon Laboratories, Inc., using the established procedures of its Intraocular R&D Laboratories. Various optical and physical aspects of the Ridley lens were evaluated including (1) dimensions, (2) weight, (3) power, (4) resolution efficiency and modulation transfer function (MTF), (5) surface sphericity by interferometry, (6) ultraviolet (UV)-visible transmission characteristic, (7) attenuated total reflectance (ATR)-Fourier transform infrared reflectance spectrum, and (8) cosmetics by visual inspection using light microscopy. This 8.5 mm diameter, 2.4 mm thick, 23 diopter biconvex IOL weighed 108 mg. The ATR spectrum, UV-visible transmission, and refractive index confirmed its poly-(methyl methacrylate) material. The 0.56 MTF value at 100 line pairs/mm, per the International Standards Organization--IOL Optics Standard, and 93% resolution efficiency in water, per the American National Standard Institute IOL Optics Standard, revealed the IOL's excellent optics. This was confirmed by 0.278 wave root mean square surface figure as measured by Zygo interferometer using a 633 nm wavelength. Visual inspection revealed rough edges with sharp corners and some surface scratches. Early clinical experience with Ridley IOLs in Bombay, India, is briefly given. The Ridley IOL had excellent optical quality, meeting the requirements of current IOL optics standards. The selection of its dimensions was guided by the human crystalline lens, and the Ridley IOL was half as bulky. Although its clinical results were mixed, successful cases inspired subsequent improvements, leading to modern, highly satisfactory IOLs. This IOL represented a revolutionary innovation in ophthalmology.

  4. 76 FR 58781 - Endangered and Threatened Species; Recovery Plans; Recovery Plan for the Kemp's Ridley Sea Turtle

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-22

    ... Plans; Recovery Plan for the Kemp's Ridley Sea Turtle AGENCY: National Marine Fisheries Service (NMFS...- National Recovery Plan (Recovery Plan) for the Kemp's Ridley Sea Turtle (Lepidochelys kempii). The Recovery...: The Bi-National Recovery Plan for the Kemp's Ridley Sea Turtle (Lepidochelys kempii) is available...

  5. 75 FR 25840 - Endangered and Threatened Species; Recovery Plans; Recovery Plan for the Kemp's Ridley Sea Turtle

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-10

    ... Plans; Recovery Plan for the Kemp's Ridley Sea Turtle AGENCIES: National Marine Fisheries Service (NMFS... Ridley Sea Turtle (Lepidochelys kempii). The Kemp's Ridley Recovery Plan is a bi-national plan developed... and interested parties to assist in the recovery of loggerhead turtles. The Plan...

  6. Schistosomus Reflexus Syndrome in Olive Ridley Sea Turtles ( Lepidochelys olivacea).

    PubMed

    Bárcenas-Ibarra, A; Rojas-Lleonart, I; Lozano-Guzmán, R I; García-Gasca, A

    2017-01-01

    The olive ridley sea turtle ( Lepidochelys olivacea), considered the most abundant sea turtle species, is listed as vulnerable on the International Union for Conservation of Nature Red List. The most important nesting areas are located in the Eastern Pacific, and congenital malformations have been previously reported in this species. The present study was conducted in a single population at El Verde beach, one of the most important nesting beaches for the species in the northwestern Mexican Pacific. The study was based on embryos that had been incubated in a controlled environment. Schistosomus reflexus syndrome (SRS) was observed in 124 of 20 257 olive ridley embryos (0.6%), comprising 124 of 400 (31%) cases of congenital malformations over a 7-month period. Affected embryos had malformations of the carapace, bridge, or plastron, resulting in exposure of the abdominal or thoracic viscera, as well as spinal malformation and abnormal positioning of limbs adjacent to the head with subsequent ankylosis. SRS phenotypes (although lethal) varied from mild to severe, although most cases were severe. SRS was mostly associated with congenital malformations in the neck (short neck, 80%), tail (anury, 38%), and flippers (different types of dysmelias, 53%). In most cases of severe SRS, ankyloses were present. Documenting these findings could be important to identify the cause of the developmental defects, and identification of the cause of the defects may be of significance to the population and to our efforts to manage this and other populations at risk.

  7. Predicted sex ratio of juvenile Kemp's Ridley sea turtles captured near Steinhatchee, Florida

    USGS Publications Warehouse

    Geis, A.A.; Barichivich, W.J.; Wibbels, T.; Coyne, M.; Landry, A.M.; Owens, D.

    2005-01-01

    The Kemp's Ridley (Lepidochelys kempii) is one of the most endangered sea turtles in the world, and it possesses temperature-dependent sex determination (TSD). Sex ratios produced under TSD can vary widely and can affect the reproductive ecology of a population. Therefore, sex ratios produced from TSD are of ecological and conservation interest. The current study validated and utilized a testosterone radioimmunoassay (RIA) to examine the sex ratio of juvenile Kemp's Ridleys inhabiting the waters near Steinhatchee, Florida. Testosterone levels were measured in blood samples collected from juvenile Kemp's Ridleys captured over a three-year period. Results of this study indicate that a significant female bias (approximately 3.7:1) occurs in the aggregation of juvenile Kemp's Ridleys inhabiting the waters near Steinhatchee.

  8. Ontogeny of energetics in leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea) sea turtle hatchlings.

    PubMed

    Jones, T Todd; Reina, Richard D; Darveau, Charles-A; Lutz, Peter L

    2007-06-01

    Changes in activity related oxygen consumption were measured in leatherback and olive ridley sea turtle hatchlings over their first month after emergence from the nest. Leatherbacks emerged with 75-90 KJ of energy in the residual yolk for growth and activity whereas olive ridleys emerged with 45 KJ. In leatherbacks (n=8), resting mass-specific oxygen consumption rates decreased by 53% over the first post-hatching month (0.34+0.03 mL O(2) h(-1) g(-1) to 0.16+0.01 mL O(2) h(-1) g(-1), respectively), while for ridleys (n=8) the fall was 35% (0.20+0.03 mL O(2) h(-1) g(-1) to 0.13+0.01 mL O(2) h(-1) g(-1), respectively). Olive ridley factorial aerobic scope doubled (1.93+0.30 to 3.97+0.51) over the first month but there was no significant increase in leatherback factorial aerobic scope (1.39+0.21 to 1.60+0.13). Leatherback hatchlings gained on average 20% initial body mass (7.68+1.66 g) over the first week, with 70 to 80% of this increase due to water accumulation. Olive ridleys gained 14% (1.83+0.16 g) in initial mass over the first week of age. We propose that the differences in aerobic scope and energy reserves are related to differences in early life ecological stratagems of these species.

  9. 75 FR 12496 - Endangered and Threatened Species; Recovery Plans; Recovery Plan for the Kemp's Ridley Sea Turtle

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-16

    ... Plans; Recovery Plan for the Kemp's Ridley Sea Turtle AGENCIES: National Marine Fisheries Service (NMFS... availability for public review of the draft Bi-National Recovery Plan (Plan) for the Kemp's Ridley Sea Turtle... turtles. The Plan identifies substantive actions needed to achieve recovery by addressing the threats...

  10. Chitinozoans in the Ordovician (Caradocian) Ridley and Pierce Limestones of central Tennessee

    SciTech Connect

    Kessler, T.E.; Siesser, W.G. )

    1990-04-01

    Chitinozoans are an extinct group of organic microfossils of uncertain biological affinity. In shape, they resemble minute (50{mu}m-2,000{mu}m) flasks and vases. Chitinozoan fossils occur in marine sedimentary rocks ranging from Cambrian to Carboniferous in age. Chitinozoan diversity is low in the Ridley and Pierce Limestones. Thirteen taxa were identified; two were left in open nomenclature, and one (Conochitina ridleyensis) is provisionally considered to be a new species. Low chitinozoan abundance and the sporadic distribution of chitinozoans in the Ridley and Pierce Limestones is believed to be the result of variable environmental conditions associated with a marine, shallow-shelf environment. The short-ranging chitinozoan taxa Lagenochitina baltica, Conochitina robusta, and Rhabdochitina turgida allow an accurate age assignment to be made for the Ridley and Pierce Limestones. These formations can now be correlated with the Conochitina hirsuta-Lagenochitina sp. A biozone, indicating an upper Blackriveran (mid-Caradocian) age assignment.

  11. Head-started Kemp’s ridley turtle (Lepidochelys kempii) nest recorded in Florida: Possible implications

    USGS Publications Warehouse

    Shaver, Donna J.; Lamont, Margaret M.; Maxwell, Sharon; Walker, Jennifer Shelby; Dillingham, Ted

    2016-01-01

    A head-started Kemp’s ridley sea turtle (Lepidochelys kempii) was documented nesting on South Walton Beach, Florida on 25 May 2015. This record supports the possibility that exposure to Florida waters after being held in captivity through 1–3 yrs of age during the head-starting process may have influenced future nest site selection of this and perhaps other Kemp’s ridley turtles. Such findings could have important ramifications for marine water experimentation and release site selection for turtles that have been reared in captivity.

  12. Notes on the Path to Competence: Comments on Ridley and Colleagues' Major Contribution

    ERIC Educational Resources Information Center

    Hatcher, Robert L.

    2011-01-01

    Focusing on the challenges of training counseling psychologists, Ridley and colleagues offer in this issue a review and critique of microskills training, the dominant training model in counseling psychology graduate programs. Recognizing the role of higher order cognitive and affective functions in expert practice, they propose a hierarchical…

  13. Waste characterization study for the Kemp's Ridley sea turtle. Technical memo

    SciTech Connect

    Malone, R.F.; Guarisco, M.

    1988-02-01

    The Kemp's Ridley sea turtle, Lepidochelys kempi, is an endangered species. The National Marine Fisheries Service's Head Start program is part of an international operation to save the turtles from extinction. Under the Head Start program, eggs from the Ridley's only known wild nesting beach at Rancho Nuevo in Mexico are transported to Padre Island on the Texas coast to be hatched. The head start enables the turtles to develop a survival advantage. The principal objective was to develop baseline waste-characterization data required to design a waste-water treatment scheme for the Galveston Head Start facility. As a secondary objective, preliminary testing of some filtration components was undertaken to determine which units were most appropriate for inclusion in a wastewater treatment scheme.

  14. The ontogeny of morphological defenses in Kemp's ridley (Lepidochelys kempii) and loggerhead (Caretta caretta) sea turtles.

    PubMed

    Salmon, Michael; Higgins, Benjamin; Stewart, Joshua; Wyneken, Jeanette

    2015-08-01

    Marine turtles are large reptiles that compensate for high juvenile mortality by producing hundreds of hatchlings during a long reproductive lifespan. Most hatchlings are taken by predators during their migration to, and while resident in, the open ocean. Their survival depends upon crypticity, minimizing movement to avoid detection, and foraging efficiently to grow to a size too difficult for predators to either handle or swallow. While these behavioral antipredator tactics are known, changes in morphology accompanying growth may also improve survival prospects. These have been only superficially described in the literature. Here, we compare the similarities and differences in presumed morphological defenses of growing loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempii) posthatchlings, related species that differ in growth rate, timing of habitat shift (the return from oceanic to neritic locations), and size at maturity. In both species, vertebral spination and carapace widening increase disproportionally as small turtles grow, but later in ontogeny, the spines regress, sooner in ridley than in loggerhead turtles. Carapace widening occurs in both species but loggerheads are always longer than they are wide whereas in Kemp's ridley turtles, the carapace becomes as wide as long. Our analysis indicates that these changes are unrelated to when each species shifts habitat but are related to turtle size. We hypothesize that the spines function in small turtles as an early defense against gape-limited predators, but changes in body shape function throughout ontogeny-initially to make small turtles too wide to swallow and later by presenting an almost flat and hardened surface that large predators (such as a sharks) are unable to grasp. The extremely wide carapace of the Kemp's ridley may compensate for its smaller adult size (and presumed greater vulnerability) than the loggerhead.

  15. Developmental cardiovascular physiology of the olive ridley sea turtle (Lepidochelys olivacea).

    PubMed

    Crossley, Dane Alan; Crossley, Janna Lee; Smith, Camilla; Harfush, Martha; Sánchez-Sánchez, Hermilo; Garduño-Paz, Mónica Vanessa; Méndez-Sánchez, José Fernando

    2017-09-01

    Our understanding of reptilian cardiovascular development and regulation has increased substantially for two species the American alligator (Alligator mississippiensis) and the common snapping turtle (Chelydra serpentina) during the past two decades. However, what we know about cardiovascular maturation in many other species remains poorly understood or unknown. Embryonic sea turtles have been studied to understand the maturation of metabolic function, but these studies have not addressed the cardiovascular system. Although prior studies have been pivotal in characterizing development, and factors that influence it, the development of cardiovascular function, which supplies metabolic function, is unknown in sea turtles. During our investigation we focused on quantifying how cardiovascular morphological and functional parameters change, to provide basic knowledge of development in the olive ridley sea turtle (Lepidochelys olivacea). Embryonic mass, as well as mass of the heart, lungs, liver, kidney, and brain increased during turtle embryo development. Although heart rate was constant during this developmental period, arterial pressure approximately doubled. Further, while embryonic olive ridley sea turtles lacked cholinergic tone on heart rate, there was a pronounced beta adrenergic tone on heart rate that decreased in strength at 90% of incubation. This beta adrenergic tone may be partially originating from the sympathetic nervous system at 90% of incubation, with the majority originating from circulating catecholamines. Data indicates that olive ridley sea turtles share traits of embryonic functional cardiovascular maturation with the American alligator (Alligator mississippiensis) but not the common snapping turtle (Chelydra serpentina). Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Differential scanning calorimetry (DSC) of semicrystalline polymers.

    PubMed

    Schick, C

    2009-11-01

    Differential scanning calorimetry (DSC) is an effective analytical tool to characterize the physical properties of a polymer. DSC enables determination of melting, crystallization, and mesomorphic transition temperatures, and the corresponding enthalpy and entropy changes, and characterization of glass transition and other effects that show either changes in heat capacity or a latent heat. Calorimetry takes a special place among other methods. In addition to its simplicity and universality, the energy characteristics (heat capacity C(P) and its integral over temperature T--enthalpy H), measured via calorimetry, have a clear physical meaning even though sometimes interpretation may be difficult. With introduction of differential scanning calorimeters (DSC) in the early 1960s calorimetry became a standard tool in polymer science. The advantage of DSC compared with other calorimetric techniques lies in the broad dynamic range regarding heating and cooling rates, including isothermal and temperature-modulated operation. Today 12 orders of magnitude in scanning rate can be covered by combining different types of DSCs. Rates as low as 1 microK s(-1) are possible and at the other extreme heating and cooling at 1 MK s(-1) and higher is possible. The broad dynamic range is especially of interest for semicrystalline polymers because they are commonly far from equilibrium and phase transitions are strongly time (rate) dependent. Nevertheless, there are still several unsolved problems regarding calorimetry of polymers. I try to address a few of these, for example determination of baseline heat capacity, which is related to the problem of crystallinity determination by DSC, or the occurrence of multiple melting peaks. Possible solutions by using advanced calorimetric techniques, for example fast scanning and high frequency AC (temperature-modulated) calorimetry are discussed.

  17. DSC2 — EDRN Public Portal

    Cancer.gov

    DSC2, a calcium-dependent glycoprotein, is a member of the desmocollin subfamily of the cadherin superfamily. These desmosomal family members, along with the desmogleins, are found primarily in epithelial cells where they constitute the adhesive proteins of the desmosome cell-cell junction and are required for cell adhesion and desmosome formation. The desmosomal family member genes are arranged in two clusters on chromosome 18, occupying less than 650 kb combined. Mutations in this gene are associated with arrhythmogenic right ventricular dysplasia-11, also known as arrhythmogenic right ventricular cardiomyopathy 11, an autosomal dominant disease characterized by partial degeneration of the myocardium of the right ventricle, electrical instability, and sudden death. Alternative splicing results in two transcript variants encoding distinct isoforms; DSC2 is encoded by Isoform 2A.

  18. The panmixia paradigm of eastern Pacific olive ridley turtles revised: consequences for their conservation and evolutionary biology.

    PubMed

    López-Castro, M C; Rocha-Olivares, A

    2005-10-01

    Previous studies of the olive ridley Lepidochelys olivacea population structure in the tropical eastern Pacific have indicated the existence of a single panmictic population ranging from Costa Rica to Mexico. This information has been used to design specific management measures to conserve primary nesting beaches in Mexico. However, little is known about olive ridleys in the Baja California Peninsula, their northernmost reproductive limit, where recent observations have shown differences in nesting female behaviour and size of hatchlings relative to other continental rookeries. We used mtDNA control region sequences from 137 turtles from five continental and four peninsular nesting sites to determine whether such differences correspond to a genetic distinction of Baja California olive ridleys or to phenotypic plasticity associated with the extreme environmental nesting conditions of this region. We found that genetic diversity in peninsular turtles was significantly lower than in continental nesting colonies. Analysis of molecular variance revealed a significant population structure (Phi ST = 0.048, P = 0.006) with the inclusion of peninsular samples. Our results: (i) suggest that the observed phenotypic variation may be associated with genetic differentiation and reproductive isolation; (ii) support the recent colonization of the eastern Pacific by Lepidochelys; (iii) reveal genetic signatures of historical expansion and colonization events; and (iv) significantly challenge the notion of a single genetic and conservation unit of olive ridleys in the eastern Pacific. We conclude that conservation measures for olive ridleys in Mexico should be revised to grant peninsular beaches special attention.

  19. Foraging area fidelity for Kemp's ridleys in the Gulf of Mexico.

    PubMed

    Shaver, Donna J; Hart, Kristen M; Fujisaki, Ikuko; Rubio, Cynthia; Sartain, Autumn R; Peña, Jaime; Burchfield, Patrick M; Gamez, Daniel Gomez; Ortiz, Jaime

    2013-07-01

    For many marine species, locations of key foraging areas are not well defined. We used satellite telemetry and switching state-space modeling (SSM) to identify distinct foraging areas used by Kemp's ridley turtles (Lepidochelys kempii) tagged after nesting during 1998-2011 at Padre Island National Seashore, Texas, USA (PAIS; N = 22), and Rancho Nuevo, Tamaulipas, Mexico (RN; N = 9). Overall, turtles traveled a mean distance of 793.1 km (±347.8 SD) to foraging sites, where 24 of 31 turtles showed foraging area fidelity (FAF) over time (N = 22 in USA, N = 2 in Mexico). Multiple turtles foraged along their migratory route, prior to arrival at their "final" foraging sites. We identified new foraging "hotspots" where adult female Kemp's ridley turtles spent 44% of their time during tracking (i.e., 2641/6009 tracking days in foraging mode). Nearshore Gulf of Mexico waters served as foraging habitat for all turtles tracked in this study; final foraging sites were located in water <68 m deep and a mean distance of 33.2 km (±25.3 SD) from the nearest mainland coast. Distance to release site, distance to mainland shore, annual mean sea surface temperature, bathymetry, and net primary production were significant predictors of sites where turtles spent large numbers of days in foraging mode. Spatial similarity of particular foraging sites selected by different turtles over the 13-year tracking period indicates that these areas represent critical foraging habitat, particularly in waters off Louisiana. Furthermore, the wide distribution of foraging sites indicates that a foraging corridor exists for Kemp's ridleys in the Gulf. Our results highlight the need for further study of environmental and bathymetric components of foraging sites and prey resources contained therein, as well as international cooperation to protect essential at-sea foraging habitats for this imperiled species.

  20. Foraging area fidelity for Kemp's ridleys in the Gulf of Mexico

    USGS Publications Warehouse

    Shaver, Donna J.; Hart, Kristen M.; Fujisaki, Ikuko; Rubio, Cynthia; Sartain-Iverson, Autumn R.; Peña, Jaime; Burchfield, Patrick M.; Gamez, Daniel Gomez; Ortiz, Jaime

    2013-01-01

    For many marine species, locations of key foraging areas are not well defined. We used satellite telemetry and switching state-space modeling (SSM) to identify distinct foraging areas used by Kemp's ridley turtles (Lepidochelys kempii) tagged after nesting during 1998–2011 at Padre Island National Seashore, Texas, USA (PAIS; N = 22), and Rancho Nuevo, Tamaulipas, Mexico (RN; N = 9). Overall, turtles traveled a mean distance of 793.1 km (±347.8 SD) to foraging sites, where 24 of 31 turtles showed foraging area fidelity (FAF) over time (N = 22 in USA, N = 2 in Mexico). Multiple turtles foraged along their migratory route, prior to arrival at their "final" foraging sites. We identified new foraging "hotspots" where adult female Kemp's ridley turtles spent 44% of their time during tracking (i.e., 2641/6009 tracking days in foraging mode). Nearshore Gulf of Mexico waters served as foraging habitat for all turtles tracked in this study; final foraging sites were located in water <68 m deep and a mean distance of 33.2 km (±25.3 SD) from the nearest mainland coast. Distance to release site, distance to mainland shore, annual mean sea surface temperature, bathymetry, and net primary production were significant predictors of sites where turtles spent large numbers of days in foraging mode. Spatial similarity of particular foraging sites selected by different turtles over the 13-year tracking period indicates that these areas represent critical foraging habitat, particularly in waters off Louisiana. Furthermore, the wide distribution of foraging sites indicates that a foraging corridor exists for Kemp's ridleys in the Gulf. Our results highlight the need for further study of environmental and bathymetric components of foraging sites and prey resources contained therein, as well as international cooperation to protect essential at-sea foraging habitats for this imperiled species.

  1. Foraging area fidelity for Kemp's ridleys in the Gulf of Mexico

    PubMed Central

    Shaver, Donna J; Hart, Kristen M; Fujisaki, Ikuko; Rubio, Cynthia; Sartain, Autumn R; Peña, Jaime; Burchfield, Patrick M; Gamez, Daniel Gomez; Ortiz, Jaime

    2013-01-01

    For many marine species, locations of key foraging areas are not well defined. We used satellite telemetry and switching state-space modeling (SSM) to identify distinct foraging areas used by Kemp's ridley turtles (Lepidochelys kempii) tagged after nesting during 1998–2011 at Padre Island National Seashore, Texas, USA (PAIS; N = 22), and Rancho Nuevo, Tamaulipas, Mexico (RN; N = 9). Overall, turtles traveled a mean distance of 793.1 km (±347.8 SD) to foraging sites, where 24 of 31 turtles showed foraging area fidelity (FAF) over time (N = 22 in USA, N = 2 in Mexico). Multiple turtles foraged along their migratory route, prior to arrival at their “final” foraging sites. We identified new foraging “hotspots” where adult female Kemp's ridley turtles spent 44% of their time during tracking (i.e., 2641/6009 tracking days in foraging mode). Nearshore Gulf of Mexico waters served as foraging habitat for all turtles tracked in this study; final foraging sites were located in water <68 m deep and a mean distance of 33.2 km (±25.3 SD) from the nearest mainland coast. Distance to release site, distance to mainland shore, annual mean sea surface temperature, bathymetry, and net primary production were significant predictors of sites where turtles spent large numbers of days in foraging mode. Spatial similarity of particular foraging sites selected by different turtles over the 13-year tracking period indicates that these areas represent critical foraging habitat, particularly in waters off Louisiana. Furthermore, the wide distribution of foraging sites indicates that a foraging corridor exists for Kemp's ridleys in the Gulf. Our results highlight the need for further study of environmental and bathymetric components of foraging sites and prey resources contained therein, as well as international cooperation to protect essential at-sea foraging habitats for this imperiled species. PMID:23919146

  2. Ophthalmic variables in rehabilitated juvenile Kemp's ridley sea turtles (Lepidochelys kempii).

    PubMed

    Gornik, Kara R; Pirie, Christopher G; Marrion, Ruth M; Wocial, Julika N; Innis, Charles J

    2016-03-15

    To determine central corneal thickness (total corneal thickness [TCT], epithelial thickness [ET], and stromal thickness [ST]), anterior chamber depth (ACD), and intraocular pressure (IOP) in Kemp's ridley sea turtles (Lepidochelys kempii). Prospective cross-sectional study. 25 healthy rehabilitated juvenile Kemp's ridley sea turtles. PROCEDURES; Body weight and straight-line standard carapace length (SCL) were recorded. All turtles underwent a complete anterior segment ophthalmic examination. Central TCT, ET, ST, and ACD were determined by use of a spectral-domain optical coherence tomography device. Intraocular pressure was determined with a rebound tonometer; the horse setting was used to measure IOP in all 25 turtles, and the undefined setting was also used to measure IOP in 20 turtles. For each variable, 3 measurements were obtained bilaterally. The mean was calculated for each eye and used for analysis purposes. The mean ± SD body weight and SCL were 3.85 ± 1.05 kg (8.47 ± 2.31 lb) and 29 ± 3 cm, respectively. The mean ± SD TCT, ET, ST, and ACD were 288 ± 23 μm, 100 ± 6 μm, 190 ± 19 μm, and 581 ± 128 μm, respectively. Mean ± SD IOP was 6.5 ± 1.0 mm Hg when measured with the horse setting and 3.8 ± 1.1 mm Hg when measured with the undefined setting. Results provided preliminary reference ranges for objective assessment of ophthalmic variables in healthy juvenile Kemp's ridley sea turtles.

  3. Assessment of ground transportation stress in juvenile Kemp's ridley sea turtles (Lepidochelys kempii).

    PubMed

    Hunt, Kathleen E; Innis, Charles J; Kennedy, Adam E; McNally, Kerry L; Davis, Deborah G; Burgess, Elizabeth A; Merigo, Constance

    2016-01-01

    Sea turtle rehabilitation centres frequently transport sea turtles for long distances to move animals between centres or to release them at beaches, yet there is little information on the possible effects of transportation-related stress ('transport stress') on sea turtles. To assess whether transport stress is a clinically relevant concern for endangered Kemp's ridley sea turtles (Lepidochelys kempii), we obtained pre-transport and post-transport plasma samples from 26 juvenile Kemp's ridley sea turtles that were transported for 13 h (n = 15 turtles) or 26 h (n = 11 turtles) by truck for release at beaches. To control for effects of handling, food restriction and time of day, the same turtles were also studied on 'control days' 2 weeks prior to transport, i.e. with two samples taken to mimic pre-transport and post-transport timing, but without transportation. Blood samples were analysed for nine clinical health measures (pH, pCO2, pO2, HCO3, sodium, potassium, ionized calcium, lactate and haematocrit) and four 'stress-associated' parameters (corticosterone, glucose, white blood cell count and heterophil-to-lymphocyte ratio). Vital signs (heart rate, respiratory rate and cloacal temperature) were also monitored. Corticosterone and glucose showed pronounced elevations due specifically to transportation; for corticosterone, this elevation was significant only for the longer transport duration, whereas glucose increased significantly after both transport durations. However, clinical health measures and vital signs showed minimal or no changes in response to any sampling event (with or without transport), and all turtles appeared to be in good clinical health after both transport durations. Thus, transportation elicits a mild, but detectable, adrenal stress response that is more pronounced during longer durations of transport; nonetheless, Kemp's ridley sea turtles can tolerate ground transportation of up to 26 h in good health. These results are likely

  4. Humphrey Ridley (1653-1708): 17th century evolution in neuroanatomy and selective cerebrovascular injections for cadaver dissection.

    PubMed

    Thakur, Jai Deep; Sonig, Ashish; Chittiboina, Prashant; Khan, Imad Saeed; Wadhwa, Rishi; Nanda, Anil

    2012-08-01

    Humphrey Ridley, M.D. (1653-1708), is a relatively unknown historical figure, belonging to the postmedieval era of neuroanatomical discovery. He was born in the market town of Mansfield, 14 miles from the county of Nottinghamshire, England. After studying at Merton College, Oxford, he pursued medicine at Leiden University in the Netherlands. In 1688, he was incorporated as an M.D. at Cambridge. Ridley authored the first original treatise in English language on neuroanatomy, The Anatomy of the Brain Containing its Mechanisms and Physiology: Together with Some New Discoveries and Corrections of Ancient and Modern Authors upon that Subject. Ridley described the venous anatomy of the eponymous circular sinus in connection with the parasellar compartment. His methods were novel, unique, and effective. To appreciate the venous anatomy, he preferred to perform his anatomical dissections on recently executed criminals who had been hanged. These cadavers had considerable venous engorgement, which made the skull base venous anatomy clearer. To enhance the appearance of the cerebral vasculature further, he used tinged wax and quicksilver in the injections. He set up experimental models to answer questions definitively, in proving that the arachnoid mater is a separate meningeal layer. The first description of the subarachnoid cisterns, blood-brain barrier, and the fifth cranial nerve ganglion with its branches are also attributed to Ridley. This historical vignette revisits Ridley's life and academic work that influenced neuroscience and neurosurgical understanding in its infancy. It is unfortunate that most of his novel contributions have gone unnoticed and uncited. The authors hope that this article will inform the neurosurgical community of Ridley's contributions to the field of neurosurgery.

  5. Pahangensin A and B, two new antibacterial diterpenes from the rhizomes of Alpinia pahangensis Ridley.

    PubMed

    Sivasothy, Yasodha; Ibrahim, Halijah; Paliany, Audra Shaleena; Alias, Siti Aisyah; Awang, Khalijah

    2013-12-01

    The rhizomes of Alpinia pahangensis Ridley yielded a new bis-labdanic diterpene for which the name pahangensin A (1) was proposed along with a new labdane diterpene, pahangensin B (2). Their structures were elucidated by spectroscopic methods including, 1D and 2D NMR techniques and LCMS-IT-TOF analysis. Pahangensin A (1) was found to be an antibacterial agent against Staphylococcus aureus, Bacillus cereus and Bacillus subtilis with MIC values less than 100 μg/mL, respectively. Pahangensin B (2) exhibited antibacterial activity (MIC <100 μg/mL) against B. cereus. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Forensic characterization of HDPE pipes by DSC.

    PubMed

    Sajwan, Madhuri; Aggarwal, Saroj; Singh, R B

    2008-03-05

    The melting behavior of 28 high density polyethylene (HDPE) pipe samples manufactured and supplied by 13 different manufacturers in India was examined by 'differential scanning calorimetry (DSC)' to find out if this parameter could be used in differentiating between these HDPE pipe samples which are chemically the same and being manufactured by different manufacturer. The results indicate that the melting temperature may serve as the useful criteria for differentiating HDPE (i) pipe samples from different sources and (ii) samples of different diameter from the same source.

  7. Sir Nicholas Harold Lloyd Ridley: 10 July 1906 - 25 May 2001.

    PubMed

    Apple, David J

    2007-01-01

    Sir Harold Ridley invented and refined the modern miracle of replacing lenses obscured by cataracts with plastic optical lenses, thus rendering a complete cataract cure. This operation, broadly termed the cataract-intraocular lens (IOL) operation, has since brought sight to many millions of people throughout the world, and continues to improve the quality of life of more than 10 million patients worldwide each year. Ridley not only launched this powerful and irreversible forward movement in the field of ophthalmology and the visual sciences, but through it he also helped give birth to the exciting and new field of artificial biodevice implantation as well as transplantation techniques now applied to many other organs and tissues of the body. He has therefore been credited with healing to create the relatively new specialty of biomedical engineering. Few of the millions of patients worldwide who now enjoy the benefits of the modern cataract - IOL operation are aware of the origin of this innovation. Indeed, few eye care professionals - even ophthalmic surgeons who implant them almost daily - are aware of the origin of the IOL - an invention that, as Harold himself liked to say, 'cured aphakia'. (The word aphakia comes from teh Greek, meaning absence of lens, the situation that occurs when a cataractous lens is surgically removed.)

  8. Metabolic and respiratory status of cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii).

    PubMed

    Innis, Charles J; Tlusty, Michael; Merigo, Constance; Weber, E Scott

    2007-08-01

    "Cold-stunning" of sea turtles has been reported as a naturally occurring stressor for many years; however, the physiologic status of cold-stunned turtles has only been partially described. This study investigated initial and convalescent venous blood gas, acid-base, and critical plasma biochemical data for 26 naturally cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii) from Cape Cod, MA, USA. Samples were analyzed for pH, pCO(2), pO(2), bicarbonate, plasma osmolality, sodium, potassium, chloride, ionized calcium, ionized magnesium, glucose, lactate, and blood urea nitrogen using a clinical point-of-care analyzer. Data were corrected for the patient's body temperature using both species-specific and more general correction methods. In general, venous blood gas, acid-base, and plasma biochemical data obtained for surviving cold-stunned Kemp's ridley sea turtles were consistent with previously documented data for sea turtles exposed to a wide range of temperatures and physiologic stressors. Data indicated that turtles were initially affected by metabolic and respiratory acidosis. Initial pH-corrected ionized calcium concentrations were lower than convalescent concentrations, and initial pH-corrected ionized magnesium concentrations were higher than convalescent concentrations.

  9. Assessment of ground transportation stress in juvenile Kemp’s ridley sea turtles (Lepidochelys kempii)

    PubMed Central

    Hunt, Kathleen E.; Innis, Charles J.; Kennedy, Adam E.; McNally, Kerry L.; Davis, Deborah G.; Burgess, Elizabeth A.; Merigo, Constance

    2016-01-01

    Sea turtle rehabilitation centres frequently transport sea turtles for long distances to move animals between centres or to release them at beaches, yet there is little information on the possible effects of transportation-related stress (‘transport stress’) on sea turtles. To assess whether transport stress is a clinically relevant concern for endangered Kemp’s ridley sea turtles (Lepidochelys kempii), we obtained pre-transport and post-transport plasma samples from 26 juvenile Kemp’s ridley sea turtles that were transported for 13 h (n = 15 turtles) or 26 h (n = 11 turtles) by truck for release at beaches. To control for effects of handling, food restriction and time of day, the same turtles were also studied on ‘control days’ 2 weeks prior to transport, i.e. with two samples taken to mimic pre-transport and post-transport timing, but without transportation. Blood samples were analysed for nine clinical health measures (pH, pCO2, pO2, HCO3, sodium, potassium, ionized calcium, lactate and haematocrit) and four ‘stress-associated’ parameters (corticosterone, glucose, white blood cell count and heterophil-to-lymphocyte ratio). Vital signs (heart rate, respiratory rate and cloacal temperature) were also monitored. Corticosterone and glucose showed pronounced elevations due specifically to transportation; for corticosterone, this elevation was significant only for the longer transport duration, whereas glucose increased significantly after both transport durations. However, clinical health measures and vital signs showed minimal or no changes in response to any sampling event (with or without transport), and all turtles appeared to be in good clinical health after both transport durations. Thus, transportation elicits a mild, but detectable, adrenal stress response that is more pronounced during longer durations of transport; nonetheless, Kemp’s ridley sea turtles can tolerate ground transportation of up to 26 h in good health. These

  10. Predicting the distribution of oceanic-stage Kemp's ridley sea turtles

    PubMed Central

    Putman, Nathan F.; Mansfield, Katherine L.; He, Ruoying; Shaver, Donna J.; Verley, Philippe

    2013-01-01

    The inaccessibility of open ocean habitat and the cryptic nature of small animals are fundamental problems when assessing the distribution of oceanic-stage sea turtles and other marine animals sharing similar life-history traits. Most methods that estimate patterns of abundance cannot be applied in situations that are extremely data limited. Here, we use a movement ecology framework to generate the first predicted distributions for the oceanic stage of the Kemp's ridley sea turtle (Lepidochelys kempii). Our simulations of particle dispersal within ocean circulation models reveal substantial annual variation in distribution and survival among simulated cohorts. Such techniques can help prioritize areas for conservation, and supply inputs for more realistic demographic models attempting to characterize population trends. PMID:23945206

  11. Glycoproteins in Rathke's gland secretions of loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempi) sea turtles.

    PubMed

    Radhakrishna, G; Chin, C C; Wold, F; Weldon, P J

    1989-01-01

    1. The Rathke's gland secretions of loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempi) sea turtles contain 20 and 10 mg of protein/ml, respectively. The proteins of each species were separated by gel filtration into two major fractions, one (35%) in the excluded volume, and one (50%) with a molecular mass of approximately 55 kDA. 2. The 55 kDa fraction from each species' secretions exhibits a single band on SDS-PAGE (Mr approximately equal to 55,000) and a single amino-terminal sequence. 3. The amino acid compositions of the two 55 kDa proteins are similar, and the first 15 residues of their amino terminus are identical. Both proteins contain glucosamine. 4. Analyses of the amino acid and amino sugar composition of the high molecular weight fractions from the two turtle species also indicate similarities; there are distinct differences between them and their 55 kDa proteins.

  12. Ultrastructure and characteristics of eggshells of the olive ridley turtle (Lepidochelys olivacea) from Gahirmatha, India.

    PubMed

    Sahoo, G; Mohapatra, B K; Sahoo, R K; Mohanty-Hejmadi, P

    1996-01-01

    The structure of a chelonian eggshell is of prime importance for the developing embryo. It acts as a protective covering as well as mediator in the exchange of heat and water. The fresh eggshell of the olive ridley (Lepidochelys olivacea) turtle displays a variety of structural forms in their aragonite framework. Its netted substrate, loose texture and poorly organised crystallites favour the easy exchange of air and water during its development. The shell consists mostly of calcium in carbonate form and K, Mg, Fe, Ni, Pb, Zn, Co, Cr, Cu, Mn and Cd in traces. Ba and Sr in traces are also a feature of the thermal analysis graph. Phosphorous was not detected in the shell and its absence eliminates an earlier suggestion of it being a key factor in the development of aragonite crystals in the inorganic structure of marine turtle eggshells. Its combustion characteristics, which have not been previously reported, are recorded.

  13. Predicting the distribution of oceanic-stage Kemp's ridley sea turtles.

    PubMed

    Putman, Nathan F; Mansfield, Katherine L; He, Ruoying; Shaver, Donna J; Verley, Philippe

    2013-10-23

    The inaccessibility of open ocean habitat and the cryptic nature of small animals are fundamental problems when assessing the distribution of oceanic-stage sea turtles and other marine animals sharing similar life-history traits. Most methods that estimate patterns of abundance cannot be applied in situations that are extremely data limited. Here, we use a movement ecology framework to generate the first predicted distributions for the oceanic stage of the Kemp's ridley sea turtle (Lepidochelys kempii). Our simulations of particle dispersal within ocean circulation models reveal substantial annual variation in distribution and survival among simulated cohorts. Such techniques can help prioritize areas for conservation, and supply inputs for more realistic demographic models attempting to characterize population trends.

  14. Molecular characterization of DSC1 orthologs in invertebrate species.

    PubMed

    Cui, Ying-Jun; Yu, Lin-Lin; Xu, Hai-Jun; Dong, Ke; Zhang, Chuan-Xi

    2012-05-01

    DSC1 and BSC1 are two founding members of a novel family of invertebrate voltage-gated cation channels with close structural and evolutionary relationships to voltage-gated sodium and calcium channels. In this study, we searched the published genome sequences for DSC1 orthologs. DSC1 orthologs were found in all 48 insect species, and in other invertebrate species belonging to phyla Mollusca, Cnidaria, Hemichordata and Echinodermata. However, DSC1 orthologs were not found in four arachnid species, Ixodes scapularis, Rhipicephalus microplus, Tetranychus urticae and Varroa destructor, two species in Annelida or any vertebrate species. We then cloned and sequenced NlSC1 and BmSC1 full-length cDNAs from the brown planthopper (Nilaparvata lugens) and the silkworm (Bombyx mori), respectively. NlSC1 and BmSC1 share about 50% identity with DSC1, and the expression of NlSC1 and BmSC1 transcripts was most abundant in the head and antenna in adults. All DSC1 orthologs contain a unique and conserved DEEA motif, instead of the EEEE or EEDD motif in classical calcium channels or the DEKA motif in sodium channels. Phylogenetic analyses revealed that DSC1 and its orthologs form a separate group distinct from the classical voltage-gated sodium and calcium channels and constitute a unique family of cation channels. The DSC1/BSC1-family channels could be potential targets of new and safe insecticides for pest control.

  15. Correlating DSC and X-Ray Measurements Of Crystallinity

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S.; Lowry, Lynn E.; Bankston, Clyde P.

    1991-01-01

    Experiment demonstrated approximate linear correlation between degree of crystallinity of multiphase polymer (as calculated from x-ray diffraction measurements) and heat of fusion of polymer (as calculated from differential scanning calorimetry (DSC) measurements). Correlation basis of simple new technique for estimating degree of crystallinity of specimens of polymer from DSC measurements alone.

  16. The use of spirometry to evaluate pulmonary function in olive ridley sea turtles (Lepidochelys olivacea) with positive buoyancy disorders.

    PubMed

    Schmitt, Todd L; Munns, Suzanne; Adams, Lance; Hicks, James

    2013-09-01

    This study utilized computed spirometry to compare the pulmonary function of two stranded olive ridley sea turtles (Lepidochelys olivacea) presenting with a positive buoyancy disorder with two healthy captive olive ridley sea turtles held in a large public aquarium. Pulmonary function test (PFT) measurements demonstrated that the metabolic cost of breathing was much greater for animals admitted with positive buoyancy than for the normal sea turtles. Positively buoyant turtles had higher tidal volumes and significantly lower breathing-frequency patterns with significantly higher expiration rates, typical of gasp-type breathing. The resulting higher energetic cost of breathing in the diseased turtles may have a significant impact on their long-term survival. The findings represent a method for clinical respiratory function analysis for an individual animal to assist with diagnosis, therapy, and prognosis. This is the first study, to our knowledge, to evaluate objectively sea turtles presenting with positive buoyancy and respiratory disease using pulmonary function tests.

  17. Two models of cross polar cap potential saturation compared: Siscoe-Hill model versus Kivelson-Ridley model

    NASA Astrophysics Data System (ADS)

    Gao, Ye; Kivelson, Margaret G.; Walker, Raymond J.

    2013-02-01

    The cross polar cap potential is considered an instantaneous monitor of the rate at which magnetic flux couples the solar wind to the Earth's magnetosphere-ionosphere system. Studies have shown that the cross polar cap potential responds linearly to the solar wind electric field under nominal solar wind conditions but asymptotes to the order of 200 kV for large electric field. Saturation of the cross polar cap potential is also found to occur in MHD simulations. Several mechanisms have been proposed to explain this phenomenon. Two well-developed models are those of Siscoe et al. (2002), herein referred to as the Siscoe-Hill model, and of Kivelson and Ridley (2008), herein referred to as the Kivelson-Ridley model. In this study, we compare the mathematical formulas as well as the predictions of the two models with data. We find that the two models predict similar saturation limits. Their difference can be expressed in terms of a factor, which is close to unity during a saturation interval. A survey of the differences in the model predictions show that, on average, the potential of the Kivelson-Ridley model is smaller than that of the Siscoe-Hill model by 10 kV. Measurements of AMIE, DMSP, PC index, and SuperDARN are used to differentiate between the two models. However, given the uncertainties of the measurements, it is impossible to conclude that one model does a better job than the other of predicting the observed cross polar cap potentials.

  18. Is the geographic distribution of nesting in the Kemp's ridley turtle shaped by the migratory needs of offspring?

    PubMed

    Putman, Nathan F; Shay, Thomas J; Lohmann, Kenneth J

    2010-09-01

    Across the geographic area that a species uses for reproduction, the density of breeding individuals is typically highest in locations where ecological factors promote reproductive success. For migratory animals, fitness depends, in part, on producing offspring that migrate successfully to habitats suitable for the next life-history stage. Thus, natural selection might favor reproduction in locations with conditions that facilitate the migration of offspring. To investigate this concept, we studied the Kemp's ridley sea turtle (Lepidochelys kempii) to determine whether coastal areas with the highest levels of nesting have particularly favorable conditions for hatchling migration. We modeled the passive drift of young Kemp's ridley turtles from seven nesting regions within the Gulf of Mexico to foraging grounds using the particle-tracking program ICHTHYOP and surface-current output from HYCOM (HYbrid Coordinate Ocean Model). Results revealed that geographic regions with conditions that facilitate successful migration to foraging grounds typically have higher abundance of nests than do regions where oceanographic conditions are less favorable and successful migration is difficult for hatchlings. Thus, our findings are consistent with the hypothesis that, for the Kemp's ridley turtle and perhaps for other migrants, patterns of abundance across the breeding range are shaped in part by conditions that promote or impede the successful migration of offspring. © The Author 2010. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved.

  19. Corticosterone and thyroxine in cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii).

    PubMed

    Hunt, Kathleen E; Innis, Charles; Rolland, Rosalind M

    2012-09-01

    Kemp's ridley sea turtles (Lepidochelys kempii), a critically endangered species, frequently strand on the shores of Cape Cod (Massachusetts, USA) in late autumn in a state of "cold-stunning" exhibiting low body temperature and related clinical issues. Stranded turtles are transported to the New England Aquarium (Boston, Massachusetts, USA) for treatment and rehabilitation. This study tested the hypothesis that cold-stunned sea turtles might exhibit high corticosterone ("stress hormone") or low thyroxine (which is often affected by temperature), or both, and that monitoring of both hormones may be useful for assessing recovery. In a retrospective analysis, 87 archived plasma samples were assayed from 56 cold-stunned juvenile Kemp's ridley sea turtles for corticosterone and free thyroxine (fT4). Upon admission, mean corticosterone was the highest yet reported for a population of sea turtles (39.3 +/- 2.5 ng/ml; mean +/- standard error of the mean [SEM]) and fT4 was usually undetectable. On admission, corticosterone was negatively correlated with white blood cell count but was not correlated with blood glucose. There were no differences in either hormone between survivors and nonsurvivors on admission. After 18+ days in recovery, surviving turtles' corticosterone dropped significantly to levels typical of baseline in other species (0.9 +/- 1.0 ng/ml) while fT4 increased significantly (1.3 +/- 1.5 pg/ml). During recovery, corticosterone was positively correlated with blood glucose and was not correlated with white blood cell count. Turtles that showed persistent deficits in feeding, activity, or both during recovery had significantly lower fT4 than did turtles with no such deficits. The "high corticosterone, low fT4" endocrine profile seen on admission may be a useful marker of cold-stunning in this and other species. Further studies are necessary to determine whether low thyroid hormones play a causal role in deficits in feeding and activity during recovery

  20. Habitat use and diving behaviour of gravid olive ridley sea turtles under riverine conditions in French Guiana

    NASA Astrophysics Data System (ADS)

    Chambault, Philippine; Giraudou, Lucie; de Thoisy, Benoît; Bonola, Marc; Kelle, Laurent; Reis, Virginie Dos; Blanchard, Fabian; Le Maho, Yvon; Chevallier, Damien

    2017-01-01

    The identification of the inter-nesting habitat used by gravid sea turtles has become a crucial factor in their protection. Their aggregation in large groups of individuals during the inter-nesting period exposes them to increased threats to their survival - particularly along the French Guiana shield, where intense legal and illegal fisheries occur. Among the three sea turtle species nesting in French Guiana, the olive ridley appears to have the most generalist diet, showing strong behavioural plasticity according to the environment encountered. The large amounts of sediments that are continuously discharged by the Amazon River create a very unusual habitat for olive ridleys, i.e. turbid waters with low salinity. This study assesses the behavioural adjustments of 20 adult female olive ridleys under such riverine conditions. Individuals were tracked by satellite from Remire-Montjoly rookery in French Guiana using tags that recorded the location and diving parameters of individuals, as well as the immediate environment of the turtles including the in situ temperature and salinity. Data concerning potential preys was provided via collection of epifauna by a trawler. Multiple behavioural shifts were observed in both horizontal and vertical dimensions. During the first half of the inter-nesting season, the turtles moved away from the nesting beach (21.9 ± 24.7 km), performing deeper (12.6 ± 7.4 m) and longer (29.7 ± 21.0 min) dives than during the second half of the period (7.4 ± 7.8 km, 10.4 ± 4.9 m and 25.9 ± 19.3 min). Olive ridleys remained in waters that were warm (range: 26-33 °C) and which fluctuated in terms of salinity (range: 19.5-36.4 psu), in a relatively small estuarine habitat covering 423 km2. If olive ridleys were foraging during this period, the potential preys that might be available were mostly crustaceans (43%) and fish (39%), as expected for the diet of this generalist species during this period. This study highlights the numerous

  1. Energetics during hatchling dispersal of the olive ridley turtle Lepidochelys olivacea using doubly labeled water.

    PubMed

    Clusella Trullas, Susana; Spotila, James R; Paladino, Frank V

    2006-01-01

    Studies of metabolism are central to the understanding of the ecology, behavior, and evolution of reptiles. This study focuses on one phase of the sea turtle life cycle, hatchling dispersal, and gives insight into energetic constraints that dispersal imposes on hatchlings. Hatchling dispersal is an energetically expensive phase in the life cycle of the olive ridley turtle Lepidochelys olivacea. Field metabolic rates (FMRs), determined using the doubly labeled water (DLW) method, for L. olivacea hatchlings digging out of their nest chamber, crawling at the sand surface, and swimming were five, four, and seven times, respectively, the resting metabolic rate (RMR). The cost of swimming was 1.5 and 1.8 times the cost of the digging and crawling phases, respectively, and we estimated that if L. olivacea hatchlings swim at frenzy levels, they can rely on yolk reserves to supply energy for only 3-6 d once they reach the ocean. We compared our RMR and FMR values by establishing an interspecific RMR mass-scaling relationship for a wide range of species in the order Testudines and found a scaling exponent of 1.06. This study demonstrates the feasibility of using the DLW method to estimate energetic costs of free-living sea turtle hatchlings and emphasizes the need for metabolic studies in various life-history stages.

  2. Seasonal reproductive cycle of the Kemp's ridley sea turtle (Lepidochelys kempi).

    PubMed

    Rostal, D C; Owens, D W; Grumbles, J S; MacKenzie, D S; Amoss, M S

    1998-02-01

    The seasonal reproductive cycle of the Kemp's ridley sea turtle (Lepidochelys kempi) was studied under seminatural conditions at the Cayman Turtle Farm, Grand Cayman, British West Indies, from June 1987 to July 1988. Male L. kempi displayed a prenuptial rise in serum testosterone 4 to 5 months prior to the mating period (March). Male testosterone then declined sharply during the mating period. Female L. kempi also displayed a prenuptial rise in serum testosterone, estradiol, and total calcium 4 to 6 months prior to the mating period (March). Female testosterone and estradiol declined during the nesting period (April to July) immediately following the mating period (March). Elevated levels in female estradiol and total calcium corresponded with the period of vitellogenesis as determined from gel electrophoresis and ultrasonography. Serum thyroxine also fluctuated seasonally with elevated levels observed in females associated with the period of vitellogenesis. L. kempi displayed a distinct seasonal reproductive cycle in captivity. Nesting in the captive study group corresponded with nesting in the wild population at Rancho Nuevo, Mexico (April to July). Female endocrine cycles during the nesting period were similar to those observed in the wild population.

  3. Differential Scanning Calorimetry (DSC) for planetary surface exploration

    NASA Technical Reports Server (NTRS)

    Gooding, James L.; Ming, Douglas W.

    1993-01-01

    Differential Scanning Calorimetry (DSC) is the quantitative measurement of the enthalpic response of a material to a systematic change in temperature. In practice, the heat flow into or outward from a sample is measured as the sample is heated or cooled at a carefully controlled rate. DSC superficially resembles, but is not the same as differential thermal analysis (DTA), which is the measurement of temperature differences between a sample and reference material as the pair is heated or cooled. The fundamental properties measured by DSC are enthalpies and temperatures of phase transitions and constant-pressure heat capacities. Depending on instrument design and the nature of the sample, high-quality DSC analyses can be obtained on only a few milligrams of solid materials. DSC requires direct contact with the sample and generally degrades, if not destroys, the sample as a consequence of heating. In laboratory applications, it is common to subject the gaseous effluent from the DSC to analysis by a separate evolved-gas analyzer (EGA).

  4. Using satellite tracking to optimize protection of long-lived marine species: olive ridley sea turtle conservation in Central Africa.

    PubMed

    Maxwell, Sara M; Breed, Greg A; Nickel, Barry A; Makanga-Bahouna, Junior; Pemo-Makaya, Edgard; Parnell, Richard J; Formia, Angela; Ngouessono, Solange; Godley, Brendan J; Costa, Daniel P; Witt, Matthew J; Coyne, Michael S

    2011-05-11

    Tractable conservation measures for long-lived species require the intersection between protection of biologically relevant life history stages and a socioeconomically feasible setting. To protect breeding adults, we require knowledge of animal movements, how movement relates to political boundaries, and our confidence in spatial analyses of movement. We used satellite tracking and a switching state-space model to determine the internesting movements of olive ridley sea turtles (Lepidochelys olivacea) (n = 18) in Central Africa during two breeding seasons (2007-08, 2008-09). These movements were analyzed in relation to current park boundaries and a proposed transboundary park between Gabon and the Republic of Congo, both created to reduce unintentional bycatch of sea turtles in marine fisheries. We additionally determined confidence intervals surrounding home range calculations. Turtles remained largely within a 30 km radius from the original nesting site before departing for distant foraging grounds. Only 44.6 percent of high-density areas were found within the current park but the proposed transboundary park would incorporate 97.6 percent of high-density areas. Though tagged individuals originated in Gabon, turtles were found in Congolese waters during greater than half of the internesting period (53.7 percent), highlighting the need for international cooperation and offering scientific support for a proposed transboundary park. This is the first comprehensive study on the internesting movements of solitary nesting olive ridley sea turtles, and it suggests the opportunity for tractable conservation measures for female nesting olive ridleys at this and other solitary nesting sites around the world. We draw from our results a framework for cost-effective protection of long-lived species using satellite telemetry as a primary tool.

  5. Using Satellite Tracking to Optimize Protection of Long-Lived Marine Species: Olive Ridley Sea Turtle Conservation in Central Africa

    PubMed Central

    Maxwell, Sara M.; Breed, Greg A.; Nickel, Barry A.; Makanga-Bahouna, Junior; Pemo-Makaya, Edgard; Parnell, Richard J.; Formia, Angela; Ngouessono, Solange; Godley, Brendan J.; Costa, Daniel P.; Witt, Matthew J.; Coyne, Michael S.

    2011-01-01

    Tractable conservation measures for long-lived species require the intersection between protection of biologically relevant life history stages and a socioeconomically feasible setting. To protect breeding adults, we require knowledge of animal movements, how movement relates to political boundaries, and our confidence in spatial analyses of movement. We used satellite tracking and a switching state-space model to determine the internesting movements of olive ridley sea turtles (Lepidochelys olivacea) (n = 18) in Central Africa during two breeding seasons (2007-08, 2008-09). These movements were analyzed in relation to current park boundaries and a proposed transboundary park between Gabon and the Republic of Congo, both created to reduce unintentional bycatch of sea turtles in marine fisheries. We additionally determined confidence intervals surrounding home range calculations. Turtles remained largely within a 30 km radius from the original nesting site before departing for distant foraging grounds. Only 44.6 percent of high-density areas were found within the current park but the proposed transboundary park would incorporate 97.6 percent of high-density areas. Though tagged individuals originated in Gabon, turtles were found in Congolese waters during greater than half of the internesting period (53.7 percent), highlighting the need for international cooperation and offering scientific support for a proposed transboundary park. This is the first comprehensive study on the internesting movements of solitary nesting olive ridley sea turtles, and it suggests the opportunity for tractable conservation measures for female nesting olive ridleys at this and other solitary nesting sites around the world. We draw from our results a framework for cost-effective protection of long-lived species using satellite telemetry as a primary tool. PMID:21589942

  6. Effect of milling on DSC thermogram of excipient adipic acid.

    PubMed

    Ng, Wai Kiong; Kwek, Jin Wang; Yuen, Aaron; Tan, Chin Lee; Tan, Reginald

    2010-03-01

    The purpose of this research was to investigate why and how mechanical milling results in an unexpected shift in differential scanning calorimetry (DSC) measured fusion enthalpy (Delta(fus)H) and melting point (T(m)) of adipic acid, a pharmaceutical excipient. Hyper differential scanning calorimetry (hyper-DSC) was used to characterize adipic acid before and after ball-milling. An experimental study was conducted to evaluate previous postulations such as electrostatic charging using the Faraday cage method, crystallinity loss using powder X-ray diffraction (PXRD), thermal annealing using DSC, impurities removal using thermal gravimetric analysis (TGA) and Karl Fischer titration. DSC thermograms showed that after milling, the values of Delta(fus)H and T(m) were increased by approximately 9% and 5 K, respectively. Previous suggestions of increased electrostatic attraction, change in particle size distribution, and thermal annealing during measurements did not explain the differences. Instead, theoretical analysis and experimental findings suggested that the residual solvent (water) plays a key role. Water entrapped as inclusions inside adipic acid during solution crystallization was partially evaporated by localized heating at the cleaved surfaces during milling. The correlation between the removal of water and melting properties measured was shown via drying and crystallization experiments. These findings show that milling can reduce residual solvent content and causes a shift in DSC results.

  7. Migratory corridors of adult female Kemp’s ridley turtles in the Gulf of Mexico

    USGS Publications Warehouse

    Shaver, Donna J.; Hart, Kristen M.; Fujisaki, Ikuko; Rubio, Cynthia; Sartain-Iverson, Autumn R.; Pena, Jaime; Gamez, Daniel Gomez; Gonzales Diaz Miron, Raul de Jesus; Burchfield, Patrick M.; Martinez, Hector J.; Ortiz, Jaime

    2016-01-01

    For many marine species, locations of migratory pathways are not well defined. We used satellite telemetry and switching state-space modeling (SSM) to define the migratory corridor used by Kemp's ridley turtles (Lepidochelys kempii) in the Gulf of Mexico. The turtles were tagged after nesting at Padre Island National Seashore, Texas, USA from 1997 to 2014 (PAIS; n = 80); Rancho Nuevo, Tamaulipas, Mexico from 2010 to 2011 (RN; n = 14); Tecolutla, Veracruz, Mexico from 2012 to 2013 (VC; n = 13); and Gulf Shores, Alabama, USA during 2012 (GS; n = 1). The migratory corridor lies in nearshore Gulf of Mexico waters in the USA and Mexico with mean water depth of 26 m and a mean distance of 20 km from the nearest mainland coast. Migration from the nesting beach is a short phenomenon that occurs from late-May through August, with a peak in June. There was spatial similarity of post-nesting migratory pathways for different turtles over a 16 year period. Thus, our results indicate that these nearshore Gulf waters represent a critical migratory habitat for this species. However, there is a gap in our understanding of the migratory pathways used by this and other species to return from foraging grounds to nesting beaches. Therefore, our results highlight the need for tracking reproductive individuals from foraging grounds to nesting beaches. Continued tracking of adult females from PAIS, RN, and VC nesting beaches will allow further study of environmental and bathymetric components of migratory habitat and threats occurring within our defined corridor. Furthermore, the existence of this migratory corridor in nearshore waters of both the USA and Mexico demonstrates that international cooperation is necessary to protect essential migratory habitat for this imperiled species.

  8. Surgical repair of severe flipper lacerations in a loggerhead, Caretta caretta, and a Kemp's ridley, Lepidochelys kempii, sea turtle.

    PubMed

    Church, Melanie L; Grafinger, Michael S; Harms, Craig A; Lewbart, Gregory A; Christian, Larry S; Beasley, Jean F

    2009-12-01

    A loggerhead, Caretta caretta, and a Kemp's ridley, Lepidochelys kempii, sea turtle were presented to the North Carolina State University, College of Veterinary Medicine for evaluation of distal flipper injuries. The goal for both animals at presentation was to preserve limb function and avoid complete amputation. A severe full-thickness flipper laceration was successfully reapposed in the first case, and a rotational flap was used to cover exposed tissue in the second case. Limb function was improved and complete amputations were avoided in both turtles.

  9. Dipolar reorientations in amorphous nimesulide: a TSDC and DSC study.

    PubMed

    Ramos, Joaquim J Moura; Diogo, Hermínio P

    2016-05-10

    The experimental techniques of differential scanning calorimetry (DSC) and thermally stimulated depolarization currents (TSDC) were used to study the thermal behavior of the pharmaceutical drug nimesulide and its slow molecular mobility in the amorphous solid state. The glass forming ability, the glass stability and the tendency for crystallization from the equilibrium melt were investigated by DSC. The general kinetic features of the main relaxation, including the dynamic fragility, were studied by both experimental techniques. The TSDC study of the secondary relaxations did not disclose fast modes. However slow modes were detected, that were ascribed to the Johari - Goldstein relaxation on the basis of an aging study.

  10. Stress responses and sexing of wild Kemp's ridley sea turtles (Lepidochelys kempii) in the northeastern Gulf of Mexico.

    PubMed

    Gregory, L F; Schmid, J R

    2001-10-01

    Plasma corticosterone, glucose, and testosterone concentrations were measured in wild, immature specimens of the highly endangered Kemp's ridley sea turtle (Lepidochelys kempii) to determine effects of acute handling stress. Thirty-nine free-ranging turtles were captured by entanglement net near the Cedar Keys, Florida. Blood samples were collected immediately after retrieval from the net, and at 30 min (n = 15) and at 60 min (n = 29) thereafter. Mean plasma corticosterone and glucose concentrations increased significantly with time. No significant difference was observed over time for mean testosterone concentrations. Approximately half of the turtles demonstrated an increase in plasma testosterone after 60 min of captivity while the others demonstrated a decrease. Initial testosterone concentrations were used to determine the sex of individual turtles. Fifty-nine percent of turtles were classified as female, 33% as male, and 8% as indeterminant. The results of this study demonstrate a responsive hypothalamic-pituitary-adrenal axis and hyperglycemia in immature Kemp's ridley turtles during acute handling stress. Copyright 2001 Academic Press.

  11. Development and evaluation of three mortality prediction indices for cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii)

    PubMed Central

    Stacy, N. I.; Innis, C. J.; Hernandez, J. A.

    2013-01-01

    Kemp's ridley sea turtle is an endangered species found in the Gulf of Mexico and along the east coast of the USA. Cold-stunned Kemp's ridley turtles are often found stranded on beaches of Massachusetts and New York in November and December each year. When found alive, turtles are transported to rehabilitation centres for evaluation and treatment. Blood gas and chemistry analytes of major clinical relevance in sea turtles were selected to develop mortality prediction indices (MPI)s. Testing the diagnostic performance of various combinations of blood gas and chemistry analytes by receiver operating characteristics (ROC) analysis resulted in the development of three mortality prediction indices. The sensitivity and specificity of the best performing MPI (based on three blood analytes: pH, pO2, and potassium) was 88 and 80%, respectively. Using ROC analysis, the area under the curve = 0.896 (95% confidence interval = 0.83–0.94). The use of validated MPIs based on four blood analytes (pH, pCO2, pO2, and potassium) could be useful for better diagnosis, treatment, and prognosis of cold-stunned sea turtles when admitted to rehabilitation facilities. PMID:27293587

  12. Nucleic acid-lipid membrane interactions studied by DSC.

    PubMed

    Giatrellis, Sarantis; Nounesis, George

    2011-01-01

    The interactions of nucleic acids with lipid membranes are of great importance for biological mechanisms as well as for biotechnological applications in gene delivery and drug carriers. The optimization of liposomal vectors for clinical use is absolutely dependent upon the formation mechanisms, the morphology, and the molecular organization of the lipoplexes, that is, the complexes of lipid membranes with DNA. Differential scanning calorimetry (DSC) has emerged as an efficient and relatively easy-to-operate experimental technique that can straightforwardly provide data related to the thermodynamics and the kinetics of the DNA-lipid complexation and especially to the lipid organization and phase transitions within the membrane. In this review, we summarize DSC studies considering nucleic acid-membrane systems, accentuating DSC capabilities, and data analysis. Published work involving cationic, anionic, and zwitterionic lipids as well as lipid mixtures interacting with RNA and DNA of different sizes and conformations are included. It is shown that despite limitations, issues such as DNA- or RNA-induced phase separation and microdomain lipid segregation, liposomal aggregation and fusion, alterations of the lipid long-range molecular order, as well as membrane-induced structural changes of the nucleic acids can be efficiently treated by systematic high-sensitivity DSC studies.

  13. Peer-Reviewed Research and the IEP: Implications of "Ridley School District v. M.R. and J.R. ex rel. E.R." (2012)

    ERIC Educational Resources Information Center

    Yell, Mitchell L.; Katsiyannis, Antonis; Losinski, Mickey; Marshall, Kelsey

    2016-01-01

    This article examines a case out of the U.S. Court of Appeals for the Third Circuit: "Ridley School District v. M.R and J.R. ex rel. E.R." (2012). The case is the first circuit court case in which the Individuals with Disabilities Education Improvement Act requirement that special education services be based on peer-reviewed research…

  14. Peer-Reviewed Research and the IEP: Implications of "Ridley School District v. M.R. and J.R. ex rel. E.R." (2012)

    ERIC Educational Resources Information Center

    Yell, Mitchell L.; Katsiyannis, Antonis; Losinski, Mickey; Marshall, Kelsey

    2016-01-01

    This article examines a case out of the U.S. Court of Appeals for the Third Circuit: "Ridley School District v. M.R and J.R. ex rel. E.R." (2012). The case is the first circuit court case in which the Individuals with Disabilities Education Improvement Act requirement that special education services be based on peer-reviewed research…

  15. Potential effects of brevetoxins and toxic elements on various health variables in Kemp's ridley (Lepidochelys kempii) and green (Chelonia mydas) sea turtles after a red tide bloom event.

    PubMed

    Perrault, Justin R; Stacy, Nicole I; Lehner, Andreas F; Mott, Cody R; Hirsch, Sarah; Gorham, Jonathan C; Buchweitz, John P; Bresette, Michael J; Walsh, Catherine J

    2017-12-15

    Natural biotoxins and anthropogenic toxicants pose a significant risk to sea turtle health. Documented effects of contaminants include potential disease progression and adverse impacts on development, immune function, and survival in these imperiled species. The shallow seagrass habitats of Florida's northwest coast (Big Bend) serve as an important developmental habitat for Kemp's ridley (Lepidochelys kempii) and green (Chelonia mydas) sea turtles; however, few studies have been conducted in this area. Our objectives were (1) to evaluate plasma analytes (mass, minimum straight carapace length, body condition index [BCI], fibropapilloma tumor score, lysozyme, superoxide dismutase, reactive oxygen/nitrogen species, plasma protein electrophoresis, cholesterol, and total solids) in Kemp's ridleys and green turtles and their correlation to brevetoxins that were released from a red tide bloom event from July-October 2014 in the Gulf of Mexico near Florida's Big Bend, and (2) to analyze red blood cells in Kemp's ridleys and green turtles for toxic elements (arsenic, cadmium, lead, mercury, selenium, thallium) with correlation to the measured plasma analytes. Positive correlations were observed between brevetoxins and α2-globulins in Kemp's ridleys and α2- and γ-globulins in green turtles, indicating potential immunostimulation. Arsenic, cadmium, and lead positively correlated with superoxide dismutase in Kemp's ridleys, suggesting oxidative stress. Lead and mercury in green turtles negatively correlated with BCI, while mercury positively correlated with total tumor score of green turtles afflicted with fibropapillomatosis, suggesting a possible association with mercury and increased tumor growth. The total tumor score of green turtles positively correlated with total protein, total globulins, α2-globulins, and γ-globulins, further suggesting inflammation and immunomodulation as a result of fibropapillomatosis. Lastly, brevetoxin concentrations were positively related

  16. Surgical removal of an abscess associated with Fusarium solani from a Kemp's ridley sea turtle (Lepidochelys kempii).

    PubMed

    Williams, Sea Rogers; Sims, Michele A; Roth-Johnson, Lois; Wickes, Brian

    2012-06-01

    A cold-stunned Kemp's ridley sea turtle, Lepidochelys kempii, developed an abscess associated with Fusarium solani, Vibrio alginolyticus, and a Shewenalla species after receiving a bite wound to the front flipper during rehabilitation. The lesion failed to respond to medical therapy and was treated successfully with surgery. Histopathology of the excised tissue demonstrated septic heterophilic inflammation with necrosis and granulation tissue, fungal elements, and bacteria, despite appropriate antimicrobial therapy. Variably thick bands of dense collagenous tissue partially surrounded affected areas which might have limited drug penetration into the tissue. Postoperative healing and eventual releases were uneventful. This is the first report of surgical treatment of cutaneous Fusarium infection in a sea turtle and supports surgery as an effective treatment for a fungal abscess in a reptile.

  17. Inter-nesting movements and habitat-use of adult female Kemp's ridley turtles in the Gulf of Mexico.

    PubMed

    Shaver, Donna J; Hart, Kristen M; Fujisaki, Ikuko; Bucklin, David; Iverson, Autumn R; Rubio, Cynthia; Backof, Thomas F; Burchfield, Patrick M; de Jesus Gonzales Diaz Miron, Raul; Dutton, Peter H; Frey, Amy; Peña, Jaime; Gomez Gamez, Daniel; Martinez, Hector J; Ortiz, Jaime

    2017-01-01

    Species vulnerability is increased when individuals congregate in restricted areas for breeding; yet, breeding habitats are not well defined for many marine species. Identification and quantification of these breeding habitats are essential to effective conservation. Satellite telemetry and switching state-space modeling (SSM) were used to define inter-nesting habitat of endangered Kemp's ridley turtles (Lepidochelys kempii) in the Gulf of Mexico. Turtles were outfitted with satellite transmitters after nesting at Padre Island National Seashore, Texas, USA, from 1998 through 2013 (n = 60); Rancho Nuevo, Tamaulipas, Mexico, during 2010 and 2011 (n = 11); and Tecolutla, Veracruz, Mexico, during 2012 and 2013 (n = 11). These sites span the range of nearly all nesting by this species. Inter-nesting habitat lies in a narrow band of nearshore western Gulf of Mexico waters in the USA and Mexico, with mean water depth of 14 to 19 m within a mean distance to shore of 6 to 11 km as estimated by 50% kernel density estimate, α-Hull, and minimum convex polygon methodologies. Turtles tracked during the inter-nesting period moved, on average, 17.5 km/day and a mean total distance of 398 km. Mean home ranges occupied were 725 to 2948 km2. Our results indicate that these nearshore western Gulf waters represent critical inter-nesting habitat for this species, where threats such as shrimp trawling and oil and gas platforms also occur. Up to half of all adult female Kemp's ridleys occupy this habitat for weeks to months during each nesting season. Because inter-nesting habitat for this species is concentrated in nearshore waters of the western Gulf of Mexico in both Mexico and the USA, international collaboration is needed to protect this essential habitat and the turtles occurring within it.

  18. Dsc Orthologs Are Required for Hypoxia Adaptation, Triazole Drug Responses, and Fungal Virulence in Aspergillus fumigatus

    PubMed Central

    Willger, Sven D.; Cornish, E. Jean; Chung, Dawoon; Fleming, Brittany A.; Lehmann, Margaret M.; Puttikamonkul, Srisombat

    2012-01-01

    Hypoxia is an environmental stress encountered by Aspergillus fumigatus during invasive pulmonary aspergillosis (IPA). The ability of this mold to adapt to hypoxia is important for fungal virulence and genetically regulated in part by the sterol regulatory element binding protein (SREBP) SrbA. SrbA is required for fungal growth in the murine lung and to ultimately cause lethal disease in murine models of IPA. Here we identified and partially characterized four genes (dscA, dscB, dscC, and dscD, here referred to as dscA-D) with previously unknown functions in A. fumigatus that are orthologs of the Schizosaccharomyces pombe genes dsc1, dsc2, dsc3, and dsc4 (dsc1-4), which encode a Golgi E3 ligase complex critical for SREBP activation by proteolytic cleavage. A. fumigatus null dscA-D mutants displayed remarkable defects in hypoxic growth and increased susceptibility to triazole antifungal drugs. Consistent with the confirmed role of these genes in S. pombe, both ΔdscA and ΔdscC resulted in reduced cleavage of the SrbA precursor protein in A. fumigatus. Inoculation of corticosteroid immunosuppressed mice with ΔdscA and ΔdscC strains revealed that these genes are critical for A. fumigatus virulence. Reintroduction of SrbA amino acids 1 to 425, encompassing the N terminus DNA binding domain, into the ΔdscA strain was able to partially restore virulence, further supporting a mechanistic link between DscA and SrbA function. Thus, we have shown for the first time the importance of a previously uncharacterized group of genes in A. fumigatus that mediate hypoxia adaptation, fungal virulence, and triazole drug susceptibility and that are likely linked to regulation of SrbA function. PMID:23104569

  19. Differential Scanning Calorimetry (DSC) for the Analysis of Activated Carbon

    DTIC Science & Technology

    1991-10-01

    impregnation procedures . It is believed that Sutcliffe-Speakman is currently using coconut - shell as the carbon precursor (instead of the New Zealand coal...microstructure facilitate the adsorption process whereby all the undesirable materials are retained. For military deployment, the activated carbon is...AD-A245 899 H.P ’ l N dI dUenm / DIFFERENTIAL SCANNING CALORIMETRY (DSC) FOR THE ANALYSIS OF ACTIVATED CARBON (U) by S.H.C. a and L.E. Cameron DTIC x

  20. 7 CFR 1710.114 - TIER, DSC, OTIER and ODSC requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 11 2012-01-01 2012-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710.114... AND GUARANTEES Loan Purposes and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements. (a... of distribution borrowers whether applied on an annual or average basis, are a TIER of 1.25, DSC of...

  1. 7 CFR 1710.114 - TIER, DSC, OTIER and ODSC requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 11 2011-01-01 2011-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710.114... AND GUARANTEES Loan Purposes and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements. (a... of distribution borrowers whether applied on an annual or average basis, are a TIER of 1.25, DSC of...

  2. 7 CFR 1710.114 - TIER, DSC, OTIER and ODSC requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 11 2014-01-01 2014-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710.114... AND GUARANTEES Loan Purposes and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements. (a... of distribution borrowers whether applied on an annual or average basis, are a TIER of 1.25, DSC of...

  3. 7 CFR 1710.114 - TIER, DSC, OTIER and ODSC requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 11 2013-01-01 2013-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710.114... AND GUARANTEES Loan Purposes and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements. (a... of distribution borrowers whether applied on an annual or average basis, are a TIER of 1.25, DSC of...

  4. PALS and DSC study of nanopores partially filled by hexadecane

    NASA Astrophysics Data System (ADS)

    Šauša, O.; Illeková, E.; Krištiak, J.; Berek, D.; Macová, E.

    2013-06-01

    The controlled porosity glasses (CPG) filled with various amount of hexadecane (HXD) in nanopores were studied both by the positron annihilation lifetime spectroscopy (PALS) and the differential scanning calorimetry (DSC) methods. Two types of CPG matrices were used with average pore sizes 12.6 and 22.2 nm. The PALS measurements showed, that when the process of large pores filling by HXD has started, the long o-Ps lifetime went down to HXD o-Ps lifetime about 3ns [1]. DSC measurements at partially filled nanopores showed always two crystallization peaks [2]. Their positions depended on average pore size of matrix. Third crystallization peak was identified in overfilled samples (only short o-Ps lifetimes were present) and their position in temperature scale was the same as for the bulk HXD peak. The latter peak was independent of the average pore size of matrices. This fact confirms the assumption that processes studied by PALS with the samples that contained smaller amount of HXD in CPG occured inside of nanopores of the matrix.

  5. Reticulation of Aqueous Polyurethane Systems Controlled by DSC Method

    PubMed Central

    Cakic, Suzana; Lacnjevac, Caslav; Rajkovic, Milos B.; Raskovic, Ljiljana; Stamenkovic, Jakov

    2006-01-01

    The DSC method has been employed to monitor the kinetics of reticulation of aqueous polyurethane systems without catalysts, and with the commercial catalyst of zirconium (CAT®XC-6212) and the highly selective manganese catalyst, the complex Mn(III)-diacetylacetonemaleinate (MAM). Among the polyol components, the acrylic emulsions were used for reticulation in this research, and as suitable reticulation agents the water emulsible aliphatic polyisocyanates based on hexamethylendoisocyanate with the different contents of NCO-groups were employed. On the basis of DSC analysis, applying the methods of Kissinger, Freeman-Carroll and Crane-Ellerstein the pseudo kinetic parameters of the reticulation reaction of aqueous systems were determined. The temperature of the examination ranged from 50°C to 450°C with the heat rate of 0.5°C/min. The reduction of the activation energy and the increase of the standard deviation indicate the catalytic action of the selective catalysts of zirconium and manganese. The impact of the catalysts on the reduction of the activation energy is the strongest when using the catalysts of manganese and applying all the three afore-said methods. The least aberrations among the stated methods in defining the kinetic parameters were obtained by using the manganese catalyst.

  6. Study on biodegradation process of lignin by FTIR and DSC.

    PubMed

    Liu, Yang; Hu, Tianjue; Wu, Zhengping; Zeng, Guangming; Huang, Danlian; Shen, Ying; He, Xiaoxiao; Lai, Mingyong; He, Yibin

    2014-12-01

    The biodegradation process of lignin by Penicillium simplicissimum was studied to reveal the lignin biodegradation mechanisms. The biodegradation products of lignin were detected using Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, different scanning calorimeter (DSC), and stereoscopic microscope. The analysis of FTIR spectrum showed the cleavage of various ether linkages (1,365 and 1,110 cm(-1)), oxidation, and demethylation (2,847 cm(-1)) by comparing the different peak values in the corresponding curve of each sample. Moreover, the differences (Tm and ΔHm values) between the DSC curves indirectly verified the FTIR analysis of biodegradation process. In addition, the effects of adding hydrogen peroxide (H2O2) to lignin biodegradation process were analyzed, which indicated that H2O2 could accelerate the secretion of the MnP and LiP and improve the enzymes activity. What is more, lignin peroxidase and manganese peroxidase catalyzed the lignin degradation effectively only when H2O2 was presented.

  7. Analytic heuristics for a fast DSC-MRI

    NASA Astrophysics Data System (ADS)

    Virgulin, M.; Castellaro, M.; Marcuzzi, F.; Grisan, E.

    2014-03-01

    Hemodynamics of the human brain may be studied with Dynamic Susceptibility Contrast MRI (DSC-MRI) imaging. The sequence of volumes obtained exhibits a strong spatiotemporal correlation, that can be exploited to predict which measurements will bring mostly the new information contained in the next frames. In general, the sampling speed is an important issue in many applications of the MRI, so that the focus of many current researches is to study methods to reduce the number of measurement samples needed for each frame without degrading the image quality. For the DSC-MRI, the frequency under-sampling of single frame can be exploited to make more frequent space or time acquisitions, thus increasing the time resolution and allowing the analysis of fast dynamics not yet observed. Generally (and also for MRI), the recovery of sparse signals has been achieved by Compressed Sensing (CS) techniques, which are based on statistical properties rather than deterministic ones.. By studying analytically the compound Fourier+Wavelet transform, involved in the processes of reconstruction and sparsification of MR images, we propose a deterministic technique for a rapid-MRI, exploiting the relations between the wavelet sparse representation of the recovered and the frequency samples. We give results on real images and on artificial phantoms with added noise, showing the superiority of the methods both with respect to classical Iterative Hard Thresholding (IHT) and to Location Constraint Approximate Message Passing (LCAMP) reconstruction algorithms.

  8. The Distribution and Conservation Status of Green Turtles (Chelonia mydas) and Olive Ridley Turtles (Lepidochelys olivacea) on Pulau Pinang beaches (Malaysia), 1995-2009.

    PubMed

    Salleh, Sarahaizad Mohd; Yobe, Mansor; Sah, Shahrul Anuar Mohd

    2012-05-01

    The Green Turtle (Chelonia mydas) and Olive Ridley Turtle (Lepidochelys olivacea) are the only sea turtles with recorded landings in the Pulau Pinang coastal area. The Green Turtle has been the most abundant and widely distributed sea turtle in this area since it was first surveyed in 1995. Statistical analysis by the Pulau Pinang Department of Fisheries on the distribution of sea turtles from 2001 through 2009 has identified Pantai Kerachut and Telok Kampi as the most strongly preferred beaches for Green Turtle landings, with records for almost every month in every year. Green Turtle tracks and nests have also been found along the coast of Pulau Pinang at Batu Ferringhi, Tanjong Bungah, Pantai Medan, Pantai Belanda, Telok Kumbar, Gertak Sanggul, Moonlight Beach, Telok Duyung, Telok Aling, Telok Bahang and Telok Katapang. The Olive Ridley Turtle is present in smaller numbers; landing and nesting have only been recorded on a few beaches. There are no previous records of Olive Ridley landings at Pantai Kerachut and Telok Kampi, but tracks and nests have been found at Telok Kumbar, Tanjong Bungah, Pantai Medan, Telok Duyung and Gertak Sanggul. A Turtle Conservation Centre has been established at Pantai Kerachut to protect these species from extinction in Pulau Pinang. This paper presents details of the records and distribution of sea turtles in Pulau Pinang from 1995 through 2009.

  9. The Distribution and Conservation Status of Green Turtles (Chelonia mydas) and Olive Ridley Turtles (Lepidochelys olivacea) on Pulau Pinang beaches (Malaysia), 1995–2009

    PubMed Central

    Salleh, Sarahaizad Mohd; Yobe, Mansor; Sah, Shahrul Anuar Mohd

    2012-01-01

    The Green Turtle (Chelonia mydas) and Olive Ridley Turtle (Lepidochelys olivacea) are the only sea turtles with recorded landings in the Pulau Pinang coastal area. The Green Turtle has been the most abundant and widely distributed sea turtle in this area since it was first surveyed in 1995. Statistical analysis by the Pulau Pinang Department of Fisheries on the distribution of sea turtles from 2001 through 2009 has identified Pantai Kerachut and Telok Kampi as the most strongly preferred beaches for Green Turtle landings, with records for almost every month in every year. Green Turtle tracks and nests have also been found along the coast of Pulau Pinang at Batu Ferringhi, Tanjong Bungah, Pantai Medan, Pantai Belanda, Telok Kumbar, Gertak Sanggul, Moonlight Beach, Telok Duyung, Telok Aling, Telok Bahang and Telok Katapang. The Olive Ridley Turtle is present in smaller numbers; landing and nesting have only been recorded on a few beaches. There are no previous records of Olive Ridley landings at Pantai Kerachut and Telok Kampi, but tracks and nests have been found at Telok Kumbar, Tanjong Bungah, Pantai Medan, Telok Duyung and Gertak Sanggul. A Turtle Conservation Centre has been established at Pantai Kerachut to protect these species from extinction in Pulau Pinang. This paper presents details of the records and distribution of sea turtles in Pulau Pinang from 1995 through 2009. PMID:24575226

  10. The influence of oceanographic features on the foraging behavior of the olive ridley sea turtle Lepidochelys olivacea along the Guiana coast

    NASA Astrophysics Data System (ADS)

    Chambault, Philippine; de Thoisy, Benoît; Heerah, Karine; Conchon, Anna; Barrioz, Sébastien; Dos Reis, Virginie; Berzins, Rachel; Kelle, Laurent; Picard, Baptiste; Roquet, Fabien; Le Maho, Yvon; Chevallier, Damien

    2016-03-01

    The circulation in the Western Equatorial Atlantic is characterized by a highly dynamic mesoscale activity that shapes the Guiana continental shelf. Olive ridley sea turtles (Lepidochelys olivacea) nesting in French Guiana cross this turbulent environment during their post-nesting migration. We studied how oceanographic and biological conditions drove the foraging behavior of 18 adult females, using satellite telemetry, remote sensing data (sea surface temperature, sea surface height, current velocity and euphotic depth), simulations of micronekton biomass (pelagic organisms) and in situ records (water temperature and salinity). The occurrence of foraging events throughout migration was located using Residence Time analysis, while an innovative proxy of the hunting time within a dive was used to identify and quantify foraging events during dives. Olive ridleys migrated northwestwards using the Guiana current and remained on the continental shelf at the edge of eddies formed by the North Brazil retroflection, an area characterized by low turbulence and high micronekton biomass. They performed mainly pelagic dives, hunting for an average 77% of their time. Hunting time within a dive increased with shallower euphotic depth and with lower water temperatures, and mean hunting depth increased with deeper thermocline. This is the first study to quantify foraging activity within dives in olive ridleys, and reveals the crucial role played by the thermocline on the foraging behavior of this carnivorous species. This study also provides novel and detailed data describing how turtles actively use oceanographic structures during post-nesting migration.

  11. Humoral immune responses to select marine bacteria in loggerhead, Caretta caretta, and Kemp's ridley, Lepidochelys kempii, sea turtles from the south eastern United States.

    PubMed

    Rodgers, Maria L; Toline, Catherine A; Rice, Charles D

    2017-10-12

    Serum from Kemp's ridley and loggerhead sea turtles was collected in summers of 2011, 2012, and 2013. Serum IgY recognition of lysate proteins from nine bacteria species and whole bacteria-specific IgY titers to these pathogens were quantified. Serum and purified IgY recognized proteins of all bacteria, with protein recognition in some species more pronounced than others. Circulating IgY titers against V. vulnificus, V. anguillarum, E. rhusiopathiae, and B. vesicularis changed over the years in Kemp's ridley turtles, while titers IgY against V. vulnificus, E. coli, V. parahaemolyticus, B. vesicularis, and M. marinum were different in loggerhead turtles. Serum lysozyme activity was constant for loggerhead turtles over the 3 years, while activity in Kemp's ridleys were lower in 2012 than 2013. Blood PCV, glucose levels, and serum protein levels were comparable to healthy turtles in previous studies, therefore, this study provides baseline information on antibody responses in healthy, wild turtles. Received 25 May 2017 accepted 09 Oct 2017 revised 15 Sep 2017.

  12. The Impact of Turtle Excluder Devices and Fisheries Closures on Loggerhead and Kemp's Ridley Strandings in the Western Gulf of Mexico

    USGS Publications Warehouse

    Lewison, R.L.; Crowder, L.B.; Shaver, D.J.

    2003-01-01

    The Sea Turtle Stranding and Salvage Network has been monitoring turtle strandings for more than 20 years in the United States. High numbers of strandings in the early to mid-1980s prompted regulations to require turtle excluder devices (TEDs) on shrimping vessels (trawlers). Following year-round TED implementation in 1991, however, stranding levels in the Gulf of Mexico increased. We evaluated the efficacy of TEDs and other management actions (e.g., fisheries closures) on loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempii) turtle populations by analyzing a long-term, stranding data set from the western Gulf of Mexico. Our analyses suggest that both sea turtle population growth and shrimping activity have contributed to the observed increase in strandings. Compliance with regulations requiring turtle excluder devices was a significant factor in accounting for annual stranding variability: low compliance was correlated with high levels of strandings. Our projections suggest that improved compliance with TED regulations will reduce strandings to levels that, in conjunction with other protective measures, should promote population recoveries for loggerhead and Kemp's ridley turtles. Local, seasonal fisheries closures, concurrent with TED enforcement, could reduce strandings to even lower levels. A seasonal closure adjacent to a recently established Kemp's ridley nesting beach may also reduce mortality of nesting adults and thus promote long-term population persistence by fostering the establishment of a robust secondary nesting site.

  13. Overriding "doing wrong" and "not doing right": validation of the Dispositional Self-Control Scale (DSC).

    PubMed

    Ein-Gar, Danit; Sagiv, Lilach

    2014-01-01

    We present the Dispositional Self-Control (DSC) Scale, which reflects individuals' tendency to override 2 types of temptations, termed doing wrong and not doing right. We report a series of 5 studies designed to test the reliability and validity of the scale. As hypothesized, high DSC predicts distant future orientation and low DSC predicts deviant behaviors such as aggression, alcohol misuse, and aberrant driving. DSC also predicts task performance among resource-depleted participants. Taken together, these findings suggest that the DSC Scale could be a useful tool toward further understanding the role of personality in overcoming self-control challenges.

  14. Determination of the oxidative stability by DSC of vegetable oils from the Amazonian area.

    PubMed

    Pardauil, Juliana J R; Souza, Luiz K C; Molfetta, Fábio A; Zamian, José R; Rocha Filho, Geraldo N; da Costa, C E F

    2011-05-01

    Differential scanning calorimetry (DSC) and a Rancimat method apparatus were applied to evaluate the oxidative stability of buriti pulp oil (Mauritia flexuosa Mart), rubber seed oil (Hevea brasiliensis), and passion fruit oil (Passiflora edulis). The Rancimat measurements taken for the oxidative induction times were performed under isothermal conditions at 100°C and in an air atmosphere. The DSC technique involved the oxidation of oil samples in an oxygen-flow DSC cell. The DSC cell temperature was set at five different isothermal temperatures: 100, 110, 120, 130 and 140°C. During the oxidation reaction, an increase in heat was observed as a sharp exothermic curve. The value T(0) represents the oxidative induction time, which is determined from the downward extrapolated DSC oxidative curve verses the time axis. These curves indicate a good correlation between the DSC T(0) and oxidative stability index (OSI) values. The DSC method is useful because it consumes less time and less sample.

  15. TG-DSC-FTIR Analysis of Cyanobacteria Pyrolysis

    NASA Astrophysics Data System (ADS)

    Supeng, Luo; Guirong, Bao; Hua, Wang; Fashe, Li; Yizhe, Li

    Pyrolysis of cyanobacteria from Dianchi lake was investigated by TG-DSC-FTIR analysis at different heating rates (10, 20, 40°C/min). The results indicated that the pyrolysis of cyanobacteria can be divided into four stages: evaporation, depolymerization, devolatilization and carbonization. Meanwhile, the initial weight-loss temperature, weight-loss extreme position, endothermic and exothermic peaks were moved to higher temperature with the increaseing of the heating rate. The kinetic analysis was made with Popescu method. It indicated that the best kinetic model for the pyrolysis of cyanobacteria was the cylindrical symmetry of the phase boundary reaction model. The main pyrolysis gases checked with real-time online FTIR were HCN, NH3, CO, CO2, water vapor and hydrocarbons.

  16. Olive Ridley Sea Turtle Hatching Success as a Function of the Microbial Abundance in Nest Sand at Ostional, Costa Rica

    PubMed Central

    Bézy, Vanessa S.; Valverde, Roldán A.; Plante, Craig J.

    2015-01-01

    Several studies have suggested that significant embryo mortality is caused by microbes, while high microbial loads are generated by the decomposition of eggs broken by later nesting turtles. This occurs commonly when nesting density is high, especially during mass nesting events (arribadas). However, no previous research has directly quantified microbial abundance and the associated effects on sea turtle hatching success at a nesting beach. The aim of this study was to test the hypothesis that the microbial abundance in olive ridley sea turtle nest sand affects the hatching success at Ostional, Costa Rica. We applied experimental treatments to alter the microbial abundance within the sand into which nests were relocated. We monitored temperature, oxygen, and organic matter content throughout the incubation period and quantified the microbial abundance within the nest sand using a quantitative polymerase chain reaction (qPCR) molecular analysis. The most successful treatment in increasing hatching success was the removal and replacement of nest sand. We found a negative correlation between hatching success and fungal abundance (fungal 18S rRNA gene copies g-1 nest sand). Of secondary importance in determining hatching success was the abundance of bacteria (bacterial 16S rRNA gene copies g-1 g-1 nest sand). Our data are consistent with the hypothesis that high microbial activity is responsible for the lower hatching success observed at Ostional beach. Furthermore, the underlying mechanism appears to be the deprivation of oxygen and exposure to higher temperatures resulting from microbial decomposition in the nest. PMID:25714355

  17. Taxonomy of the Caribbean sponge Dragmacidon reticulatum (Ridley & Dendy, 1886) (Porifera, Demospongiae, Axinellida), with the description of a new species.

    PubMed

    Zea, Sven; Pulido, Alejandra

    2016-05-25

    Although there is a long history of taxonomic investigation in Caribbean sponges, there are still many undescribed species. Furthermore, field observations and corroborating morphological analyses are revealing that what was believed to be single, somewhat variable species, may consist of two or more species, often easier to distinguish once well characterized. This is the case for Dragmacidon reticulatum (Ridley & Dendy, 1886) (Porifera, Demospongiae, Axinellida, Axinellidae), a rather well-known sponge, with an ample distribution and presence in rocky and reef environments of the tropical and subtropical Western Atlantic, with local records in the majority of the countries of the area, from Bermuda to Brazil. Field observations and a detailed review of material from different areas, including some type specimens, led us to the distinction of two different species in terms of external morphology, size of spicules, and skeletal architecture. The distinction was confirmed in the Bahamas and Santa Marta, Colombia, where the two species coexist. One of the species is Dragmacidon reticulatum sensu stricto, but for the other there is need to erect a new name, for which we propose Dragmacidon alvarezae n. sp. The purpose of the present work is to describe, illustrate and compare these two species.

  18. Effects of acute fresh water exposure on water flux rates and osmotic responses in Kemp's ridley sea turtles (Lepidochelys kempi)

    NASA Technical Reports Server (NTRS)

    Ortiz, R. M.; Patterson, R. M.; Wade, C. E.; Byers, F. M.

    2000-01-01

    Water flux rates and osmotic responses of Kemp's Ridley sea turtles (Lepidochelys kempi) acutely exposed to fresh water were quantified. Salt-water adapted turtles were exposed to fresh water for 4 d before being returned to salt water. During the initial salt water phase, absolute and relative water flux rates were 1.2+/-0.1 l d(-1) and 123.0+/-6.8 ml kg(-1) d(-1), respectively. When turtles were exposed to fresh water, rates increased by approximately 30%. Upon return to salt water, rates decreased to original levels. Plasma osmolality, Na(+), K(+), and Cl(-) decreased during exposure to fresh water, and subsequently increased during the return to salt water. The Na(+):K(+) ratio was elevated during the fresh water phase and subsequently decreased upon return to salt water. Aldosterone and corticosterone were not altered during exposure to fresh water. Elevated water flux rates during fresh water exposure reflected an increase in water consumption, resulting in a decrease in ionic and osmotic concentrations. The lack of a change in adrenocorticoids to acute fresh water exposure suggests that adrenal responsiveness to an hypo-osmotic environment may be delayed in marine turtles when compared to marine mammals.

  19. Metals and metalloids in whole blood and tissues of Olive Ridley turtles (Lepidochelys olivacea) from La Escobilla Beach (Oaxaca, Mexico).

    PubMed

    Cortés-Gómez, Adriana A; Fuentes-Mascorro, Gisela; Romero, Diego

    2014-12-15

    Concentrations of eight metals and metalloids (Pb, Cd, Cu, Zn, Mn, Se, Ni and As) were evaluated from 41 nesting females (blood) and 13 dead (tissues) Olive Ridley turtles (Lepidochelys olivacea), a species classified as vulnerable and also listed in Appendix I of the Convention of International Trade in Endangered Species (CITES). The mean blood, liver and kidney lead concentration were 0.02 ± 0.01, 0.11 ± 0.08 and 0.06 ± 0.03 μ gg(-1) ww respectively, values lower than other turtle species and locations, which it could be due to the gradual disuse of leaded gasoline in Mexico and Central America since the 1990s. Mean concentration of cadmium was 0.17 ± 0.08 (blood), 82.88 ± 36.65 (liver) and 150.88 ± 110.9 9μg g(-1) (kidney). To our knowledge, the mean renal cadmium levels found is the highest ever reported worldwide for any sea turtle species, while other six elements showed a concentration similar to other studies in sea turtles.

  20. Effects of acute fresh water exposure on water flux rates and osmotic responses in Kemp's ridley sea turtles (Lepidochelys kempi).

    PubMed

    Ortiz, R M; Patterson, R M; Wade, C E; Byers, F M

    2000-09-01

    Water flux rates and osmotic responses of Kemp's Ridley sea turtles (Lepidochelys kempi) acutely exposed to fresh water were quantified. Salt-water adapted turtles were exposed to fresh water for 4 d before being returned to salt water. During the initial salt water phase, absolute and relative water flux rates were 1.2+/-0.1 l d(-1) and 123.0+/-6.8 ml kg(-1) d(-1), respectively. When turtles were exposed to fresh water, rates increased by approximately 30%. Upon return to salt water, rates decreased to original levels. Plasma osmolality, Na(+), K(+), and Cl(-) decreased during exposure to fresh water, and subsequently increased during the return to salt water. The Na(+):K(+) ratio was elevated during the fresh water phase and subsequently decreased upon return to salt water. Aldosterone and corticosterone were not altered during exposure to fresh water. Elevated water flux rates during fresh water exposure reflected an increase in water consumption, resulting in a decrease in ionic and osmotic concentrations. The lack of a change in adrenocorticoids to acute fresh water exposure suggests that adrenal responsiveness to an hypo-osmotic environment may be delayed in marine turtles when compared to marine mammals.

  1. Effects of acute fresh water exposure on water flux rates and osmotic responses in Kemp's ridley sea turtles (Lepidochelys kempi)

    NASA Technical Reports Server (NTRS)

    Ortiz, R. M.; Patterson, R. M.; Wade, C. E.; Byers, F. M.

    2000-01-01

    Water flux rates and osmotic responses of Kemp's Ridley sea turtles (Lepidochelys kempi) acutely exposed to fresh water were quantified. Salt-water adapted turtles were exposed to fresh water for 4 d before being returned to salt water. During the initial salt water phase, absolute and relative water flux rates were 1.2+/-0.1 l d(-1) and 123.0+/-6.8 ml kg(-1) d(-1), respectively. When turtles were exposed to fresh water, rates increased by approximately 30%. Upon return to salt water, rates decreased to original levels. Plasma osmolality, Na(+), K(+), and Cl(-) decreased during exposure to fresh water, and subsequently increased during the return to salt water. The Na(+):K(+) ratio was elevated during the fresh water phase and subsequently decreased upon return to salt water. Aldosterone and corticosterone were not altered during exposure to fresh water. Elevated water flux rates during fresh water exposure reflected an increase in water consumption, resulting in a decrease in ionic and osmotic concentrations. The lack of a change in adrenocorticoids to acute fresh water exposure suggests that adrenal responsiveness to an hypo-osmotic environment may be delayed in marine turtles when compared to marine mammals.

  2. Profiles in Leadership: Donald E. Francke, MSc, DSc (Hon)

    PubMed Central

    Stevenson, James G.; Beham, Rachel E.; Weber, Robert J.

    2013-01-01

    The Director’s Forum series is designed to guide pharmacy leaders in establishing patient-centered services in hospitals and health systems. August 2013 marked the 50th anniversary of the publication of the Mirror to Hospital Pharmacy, the results of a federally funded comprehensive study of pharmacy services in the United States. The late Don E. Francke, MS, DSc, was the lead author of the Mirror and the principal investigator for the US Public Health Service grant W-45. To celebrate the anniversary of the Mirror, the Director’s Forum is profiling the leadership styles of Drs. Latiolais and Francke. September’s article highlighted Dr. Clifton J. Latiolais; this month’s Director’s Forum reviews Dr. Francke’s biography and key career accomplishments, describes his leadership philosophy, and translates that philosophy to today’s health care challenges. Don’s influence on health system pharmacy serves as an example of effective leadership. This historical perspective provides directors of pharmacy a valuable leadership view as they develop strategies to enhance patient-centered pharmacy services. PMID:24421553

  3. Basal and stress-induced corticosterone levels in olive ridley sea turtles (Lepidochelys olivacea) in relation to their mass nesting behavior.

    PubMed

    Valverde, R A; Owens, D W; MacKenzie, D S; Amoss, M S

    1999-11-01

    Adrenocortical responsiveness to turning stress was examined in wild, reproductively-active olive ridley sea turtles (Lepidochelys olivacea) in relation to their mass nesting (arribada) behavior. We hypothesized that the high sensitivity threshold (HST) observed in ovipositing sea turtles is associated with a diminished sensitivity of the hypothalamo-pituitary-adrenal (HPA) axis to stressful stimuli in arribada females. We tested this hypothesis by determining whether arribada females exhibited an increased activation threshold of the HPA axis to an imposed stressor (turning stress). Mean basal corticosterone (B) and glucose levels were below 1.0 ng/ml and 60 mg/dl, respectively. Basal B remained unchanged throughout a 24-hr period in basking females. Most animals responded to turning stress with elevated mean B levels (up to 6.5 ng/ml after 6 hr) and no increase in circulating glucose. Nearly 50% of females (and none of the males) were refractory to the stimulation. Males exhibited the most rapid response, with B levels significantly elevated by 20 min over basal levels. Among females, arribada and solitary nesters exhibited a slower rate of response than basking, non-nesting animals. These results demonstrate that olive ridleys exhibit stress-induced changes in circulating B which are slower than those observed in most reptilian and in mammalian, avian, and piscine species. Furthermore, the presence of refractory females and the relatively slower increase in B in arribada and solitary nesters indicate a hyporesponsiveness of the HPA axis to turning stress in nesting olive ridleys. The hyporesponsiveness may be part of a mechanism to facilitate arribada nesting. J. Exp. Zool. 284:652-662, 1999. Copyright 1999 Wiley-Liss, Inc.

  4. Variability in age and size at maturation, reproductive longevity, and long-term growth dynamics for Kemp's ridley sea turtles in the Gulf of Mexico

    PubMed Central

    Goshe, Lisa R.; Coggins, Lewis; Shaver, Donna J.; Higgins, Ben; Landry, Andre M.; Bailey, Rhonda

    2017-01-01

    Effective management of protected sea turtle populations requires knowledge not only of mean values for demographic and life-history parameters, but also temporal and spatial trends, variability, and underlying causes. For endangered Kemp’s ridley sea turtles (Lepidochelys kempii), the need for baseline information of this type has been emphasized during attempts to understand causes underlying the recent truncation in the recovery trajectory for nesting females. To provide insight into variability in age and size at sexual maturation (ASM and SSM) and long-term growth patterns likely to influence population trends, we conducted skeletochronological analysis of humerus bones from 333 Kemp’s ridleys stranded throughout the Gulf of Mexico (GOM) from 1993 to 2010. Ranges of possible ASMs (6.8 to 21.8 yr) and SSMs (53.3 to 68.3 cm straightline carapace length (SCL)) estimated using the “rapprochement” skeletal growth mark associated with maturation were broad, supporting incorporation of a maturation schedule in Kemp’s ridley population models. Mean ASMs estimated from rapprochement and by fitting logistic, generalized additive mixed, and von Bertalanffy growth models to age and growth data ranged from 11 to 13 yr; confidence intervals for the logistic model predicted maturation of 95% of the population between 11.9 and 14.8 yr. Early juvenile somatic growth rates in the GOM were greater than those previously reported for the Atlantic, indicating potential for differences in maturation trajectories between regions. Finally, long-term, significant decreases in somatic growth response were found for both juveniles and adults, which could influence recruitment to the reproductive population and observed nesting population trends. PMID:28333937

  5. Variability in age and size at maturation, reproductive longevity, and long-term growth dynamics for Kemp's ridley sea turtles in the Gulf of Mexico.

    PubMed

    Avens, Larisa; Goshe, Lisa R; Coggins, Lewis; Shaver, Donna J; Higgins, Ben; Landry, Andre M; Bailey, Rhonda

    2017-01-01

    Effective management of protected sea turtle populations requires knowledge not only of mean values for demographic and life-history parameters, but also temporal and spatial trends, variability, and underlying causes. For endangered Kemp's ridley sea turtles (Lepidochelys kempii), the need for baseline information of this type has been emphasized during attempts to understand causes underlying the recent truncation in the recovery trajectory for nesting females. To provide insight into variability in age and size at sexual maturation (ASM and SSM) and long-term growth patterns likely to influence population trends, we conducted skeletochronological analysis of humerus bones from 333 Kemp's ridleys stranded throughout the Gulf of Mexico (GOM) from 1993 to 2010. Ranges of possible ASMs (6.8 to 21.8 yr) and SSMs (53.3 to 68.3 cm straightline carapace length (SCL)) estimated using the "rapprochement" skeletal growth mark associated with maturation were broad, supporting incorporation of a maturation schedule in Kemp's ridley population models. Mean ASMs estimated from rapprochement and by fitting logistic, generalized additive mixed, and von Bertalanffy growth models to age and growth data ranged from 11 to 13 yr; confidence intervals for the logistic model predicted maturation of 95% of the population between 11.9 and 14.8 yr. Early juvenile somatic growth rates in the GOM were greater than those previously reported for the Atlantic, indicating potential for differences in maturation trajectories between regions. Finally, long-term, significant decreases in somatic growth response were found for both juveniles and adults, which could influence recruitment to the reproductive population and observed nesting population trends.

  6. Organohalogen contaminants in blood of Kemp's ridley (Lepidochelys kempii) and green sea turtles (Chelonia mydas) from the Gulf of Mexico.

    PubMed

    Swarthout, Robert F; Keller, Jennifer M; Peden-Adams, Margie; Landry, Andre M; Fair, Patricia A; Kucklick, John R

    2010-02-01

    The threat that exposure to organohalogen (OH) contaminants poses to endangered populations of Kemp's ridley (Lepidochelys kempii) and green sea turtles (Chelonia mydas) is not well understood, partly because few OH data are available. Blood samples from live juvenile and sub-adult L. kempii (n = 46) and C. mydas (n = 9) from the Gulf of Mexico and from L. kempii from the southeastern US coast (n = 3) were extracted using microwave-assisted extraction, and analyzed by large volume injection gas chromatography-mass spectrometry for 85 polychlorinated biphenyls (PCBs), 25 organochlorine pesticides (OCPs) and 27 polybrominated diphenyl ethers (PBDEs). Plasma chemistries, hematology and immune responses were also assessed. Concentrations of SigmaPCBs (geometric mean, range: 3190 pg g(-1), 227-21590 pg g(-1) blood), SigmaDDTs (geometric mean, range: 541 pg g(-1), 161-4310 pg g(-1) blood) and OCPs in L. kempii from the Gulf were comparable to those reported in L. kempii from the Atlantic. SigmaPBDEs were detected in all samples (geometric mean, range: 146 pg g(-1), 19.5-1450 pg g(-1) blood), with PBDE 47, 99, 100, 153 and 154 being the predominant congeners. SigmaPCBs, SigmaDDTs and Sigmachlordanes were one order of magnitude lower in green turtles, and SigmaPBDE concentrations were lower by half due to trophic level differences. L. kempii from the southeast USA had higher percentages of highly chlorinated PCBs indicating exposure to Aroclor 1268. Blood urea nitrogen was positively correlated to Sigmachlordanes, and SigmaPCBs were inversely correlated to creatine phosphokinase in L. kempii. These data help establish baseline contaminant concentrations in live L. kempii and C. mydas.

  7. Diatoms and Other Epibionts Associated with Olive Ridley (Lepidochelys olivacea) Sea Turtles from the Pacific Coast of Costa Rica

    PubMed Central

    Majewska, Roksana; Santoro, Mario; Bolaños, Federico; Chaves, Gerardo; De Stefano, Mario

    2015-01-01

    Although the sea turtles have long been familiar and even iconic to marine biologists, many aspects of their ecology remain unaddressed. The present study is the first of the epizoic diatom community covering the olive ridley turtle’s (Lepidochelys olivacea) carapace and the first describing diatoms living on sea turtles in general, with the primary objective of providing detailed information on turtle epibiotic associations. Samples of turtle carapace including the associated diatom biofilm and epizoic macro-fauna were collected from Ostional beach (9° 59´ 23.7´´ N 85° 41´ 52.6´´ W), Costa Rica, during the arribada event in October 2013. A complex diatom community was present in every sample. In total, 11 macro-faunal and 21 diatom taxa were recorded. Amongst diatoms, the most numerous were erect (Achnanthes spp., Tripterion spp.) and motile (Haslea sp., Navicula spp., Nitzschia spp., Proschkinia sp.) forms, followed by adnate Amphora spp., while the most common macro-faunal species was Stomatolepas elegans (Cirripedia). Diatom densities ranged from 8179 ± 750 to 27685 ± 4885 cells mm-2. Epizoic microalgae were either partly immersed or entirely encapsulated within an exopolymeric coat. The relatively low diatom species number, stable species composition and low inter-sample dissimilarities (14.4% on average) may indicate a mutualistic relationship between the epibiont and the basibiont. Dispersal of sea turtle diatoms is probably highly restricted and similar studies will help to understand both diatom diversity, evolution and biogeography, and sea turtle ecology and foraging strategies. PMID:26083535

  8. Diatoms and Other Epibionts Associated with Olive Ridley (Lepidochelys olivacea) Sea Turtles from the Pacific Coast of Costa Rica.

    PubMed

    Majewska, Roksana; Santoro, Mario; Bolaños, Federico; Chaves, Gerardo; De Stefano, Mario

    2015-01-01

    Although the sea turtles have long been familiar and even iconic to marine biologists, many aspects of their ecology remain unaddressed. The present study is the first of the epizoic diatom community covering the olive ridley turtle's (Lepidochelys olivacea) carapace and the first describing diatoms living on sea turtles in general, with the primary objective of providing detailed information on turtle epibiotic associations. Samples of turtle carapace including the associated diatom biofilm and epizoic macro-fauna were collected from Ostional beach (9° 59´ 23.7´´ N 85° 41´ 52.6´´ W), Costa Rica, during the arribada event in October 2013. A complex diatom community was present in every sample. In total, 11 macro-faunal and 21 diatom taxa were recorded. Amongst diatoms, the most numerous were erect (Achnanthes spp., Tripterion spp.) and motile (Haslea sp., Navicula spp., Nitzschia spp., Proschkinia sp.) forms, followed by adnate Amphora spp., while the most common macro-faunal species was Stomatolepas elegans (Cirripedia). Diatom densities ranged from 8179 ± 750 to 27685 ± 4885 cells mm-2. Epizoic microalgae were either partly immersed or entirely encapsulated within an exopolymeric coat. The relatively low diatom species number, stable species composition and low inter-sample dissimilarities (14.4% on average) may indicate a mutualistic relationship between the epibiont and the basibiont. Dispersal of sea turtle diatoms is probably highly restricted and similar studies will help to understand both diatom diversity, evolution and biogeography, and sea turtle ecology and foraging strategies.

  9. Level II scour analysis for Bridge 37 (DUXBTH00120037) on Town Highway 12, crossing Ridley Brook, Duxbury, Vermont

    USGS Publications Warehouse

    Wild, Emily C.; Ivanhoff, Michael A.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure DUXBTH00120037 on Town Highway 12 crossing Ridley Brook, Duxbury, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in north central Vermont. The 10.1-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest upstream and downstream of the bridge. In the study area, Ridley Brook has an incised, straight channel with a slope of approximately 0.04 ft/ft, an average channel top width of 67 ft and an average bank height of 9 ft. The channel bed material ranges from gravel to boulders with a median grain size (D50) of 123 mm (0.404 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 1, 1996, indicated that the reach was stable. The Town Highway 12 crossing of Ridley Brook is a 33-ft-long, two-lane bridge consisting of five 30-ft steel rolled beams (Vermont Agency of Transportation, written communication, October 13, 1995). The opening length of the structure parallel to the bridge face is 30 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 50 degrees to the opening while the measured opening-skew-to-roadway is 20 degrees. A scour hole 2 ft deeper than the mean thalweg depth was observed along the right abutment and downstream

  10. Gelatinisation kinetics of corn and chickpea starches using DSC, RVA, and dynamic rheometry

    USDA-ARS?s Scientific Manuscript database

    The gelatinisation kinetics (non-isothermal) of corn and chickpea starches at different heating rates were calculated using differential scanning calorimetry (DSC), rapid visco analyser (RVA), and oscillatory dynamic rheometry. The data obtained from the DSC thermogram and the RVA profiles were fitt...

  11. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Digital selective calling (DSC) operating procedures. 80.103 Section 80.103 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating...

  12. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Digital selective calling (DSC) operating... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating procedures..., “Operational Procedures for the Use of Digital Selective-Calling Equipment in the Maritime Mobile...

  13. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequencies for digital selective calling (DSC). 80.359 Section 80.359 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... for digital selective calling (DSC). (a) General purpose calling. The following table describes...

  14. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Digital selective calling (DSC) operating procedures. 80.103 Section 80.103 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating...

  15. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies for digital selective calling (DSC... for digital selective calling (DSC). (a) General purpose calling. The following table describes the...-R Recommendation M.541-9, “Operational Procedures for the Use of Digital Selective-Calling...

  16. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Digital selective calling (DSC) operating... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating procedures..., “Operational Procedures for the Use of Digital Selective-Calling Equipment in the Maritime Mobile...

  17. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequencies for digital selective calling (DSC). 80.359 Section 80.359 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... for digital selective calling (DSC). (a) General purpose calling. The following table describes...

  18. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Digital selective calling (DSC) operating procedures. 80.103 Section 80.103 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating...

  19. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies for digital selective calling (DSC). 80.359 Section 80.359 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... for digital selective calling (DSC). (a) General purpose calling. The following table describes...

  20. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies for digital selective calling (DSC... for digital selective calling (DSC). (a) General purpose calling. The following table describes the...-R Recommendation M.541-9, “Operational Procedures for the Use of Digital Selective-Calling...

  1. The characterization of cytosolic glutathione transferase from four species of sea turtles: loggerhead (Caretta caretta), green (Chelonia mydas), olive ridley (Lepidochelys olivacea), and hawksbill (Eretmochelys imbricata).

    PubMed

    Richardson, Kristine L; Gold-Bouchot, Gerardo; Schlenk, Daniel

    2009-08-01

    Glutathione s-transferases (GST) play a critical role in the detoxification of exogenous and endogenous electrophiles, as well as the products of oxidative stress. As compared to mammals, GST activity has not been extensively characterized in reptiles. Throughout the globe, most sea turtle populations face the risk of extinction. Of the natural and anthropogenic threats to sea turtles, the effects of environmental chemicals and related biochemical mechanisms, such as GST catalyzed detoxification, are probably the least understood. In the present study, GST activity was characterized in four species of sea turtles with varied life histories and feeding strategies: loggerhead (Caretta caretta), green (Chelonia mydas), olive ridley (Lepidochelys olivacea), and hawksbill (Eretmochelys imbricata). Although similar GST kinetics was observed between species, rates of catalytic activities using class-specific substrates show inter- and intra-species variation. GST from the spongivorous hawksbill sea turtle shows 3-4.5 fold higher activity with the substrate 4-nitrobenzylchloride than the other 3 species. GST from the herbivorous green sea turtle shows 3 fold higher activity with the substrate ethacrynic acid than the carnivorous olive ridley sea turtle. The results of this study may provide insight into differences in biotransformation potential in the four species of sea turtles and the possible health impacts of contaminant biotransformation by sea turtles.

  2. [Chemical composition of eggs of the Olive Ridley Lepidochelys olivacea (Testudines: Cheloniidae) and it's potential as a food source].

    PubMed

    Castro-González, María Isabel; Pérez-Gil Romo, Fernando

    2011-12-01

    The Olive Ridley is a worldwide distributed species with high nesting production per season, and in La Escobilla Oaxaca, México, there is a 70% of non-hatched eggs that are lost. In order to evaluate their potential use as a source for human and animal food products, their chemical composition was analyzed. Lyophilized egg samples from 25 turtles were obtained and were analyzed following the analytical methods for fatty acids, protein, fat, ash, moisture, amino acids, vitamins, cholesterol and microbiological agents. The analytical composition obtained was (g/100g): moisture (4.7), ash (3.8), protein (53.7), and fat (47.4). The essential amino acid (g aa/100g protein) content was: Ile (4.4), Lys (6.6), Leu (7.4), Met+Cys (8.8), Phe+Tyr (10.8). The vitamin content was: retinol (340 microg/100g), cholecalciferol (5.91 microg/100g) and 8.6 mg/100 tocopherol, 0.3 mg/100g thiamine and 1.1 mg/100g riboflavin. The total lipid content (TL), fatty acids (FA), and cholesterol (Chol) were divided into three groups based on the weight of the turtle: (TL) (44.3-48.7-49.1g/100g) and (Chol) (518.4-522.5 mg/100g-728.7). A total of 17 Saturated FA (SFA), 8 Monounsaturated FA (MUFA) and 11 Polyunsaturated FA (PUFA) were identified. The most abundant SFA (mg/100g) were: C14:0 (445-772), C16:0 (485-1263); MUFA: C16:1 (456-716), C18:1n-9c (904-1754), and PUFA: C20:4n-6 (105-217); two n-3 fatty acids were identified EPA (48-103) and DHA (97-189).There were significant differences (Fisher, p < 0.05) for: (Chol), total FA, SFA, MUFA, PUFAs and n-3 (EPA + DHA) FA. It was not detected any microbiological agent. In conclusion, lyophilized L. olivacea eggs are an option for its inclusion in the development of food products as they can be used as a high quality biological protein and n-3 fatty acid source for fortification and enrichment.

  3. Expression of the Drosophila Secreted Cuticle Protein 73 (dsc73) Requires Shavenbaby

    PubMed Central

    Andrew, Deborah J.; Baker, Bruce S.

    2010-01-01

    Low stringency genomic library screens with genomic fragments from the sex determination gene doublesex identified the Drosophila secreted cuticle protein 73 (dsc73) gene, which encodes an 852-residue protein with an N-terminal signal sequence. In embryos, dsc73 RNA and protein are expressed to high levels in the epidermal cells that secrete the larval cuticle as well as in other cuticle-secreting tissues such as the trachea and salivary duct. Embryonic expression of dsc73 requires Shavenbaby, a transcription factor regulating cuticle formation. Double-labeling experiments with αCrb and αSAS reveal that, as with chitin and other known cuticle proteins, Dsc73 is secreted apically. Zygotic loss of dsc73 results in larval lethality but loss does not result in overt patterning defects or overt morphological defects in the embryonic tissues in which it is expressed. Thus, dsc73 encodes a novel secreted protein, and it is conserved within the Drosophila group. dsc73 may serve as a useful embryonic marker for cuticular patterning. PMID:18351665

  4. Thermodynamic investigations of nitroxoline sublimation by simultaneous DSC-FTIR method and isothermal TG analysis.

    PubMed

    Gao, Gau-Yi; Lin, Shan-Yang

    2010-01-01

    To investigate the physicochemical characteristics, thermodynamics, possible sublimation process and kinetics of nitroxoline, differential scanning calorimetry (DSC), isothermal thermogravimetry (TG), and Fourier transform infrared (FTIR) microspectroscopy equipped with a micro hot-stage of DSC microscopy assembly (simultaneous DSC-FTIR method) were used. The DSC result indicates that nitroxoline exhibited a sharp endothermic peak at 182 degrees C with enthalpy of 103.1 J/g due to the melting point of nitroxoline. A sublimation behavior of nitroxoline was found from 129 degrees C by gradual weight loss in TG curve. However, the nonisothermal DSC-FTIR method reveals that the temperature at 95 degrees C was the onset temperature of nitroxoline sublimation. A significant difference between DSC-FTIR method and TG analysis suggests that the simultaneous DSC-FTIR method was more sensitive than that of the TG analysis to detect the beginning temperature of nitroxoline sublimation. The sublimation kinetics of nitroxoline determined by isothermal TG analysis evidenced that the zero-order kinetics was followed over the sublimation time. The sublimation enthalpy correction was also carried out by a group additivity approach for the estimation of heat capacity. The enthalpy of nitroxoline sublimation estimated was 86.14 KJ/mol at 298.15 K.

  5. Kuipers works with DSC Hardware in the U.S. Laboratory

    NASA Image and Video Library

    2012-01-16

    ISS030-E-155917 (16 Jan. 2012) --- European Space Agency astronaut Andre Kuipers, Expedition 30 flight engineer, prepares to place Diffusion Soret Coefficient (DSC) hardware in stowage containers in the Destiny laboratory of the International Space Station.

  6. DSC study of technical grade phase change heat storage materials for solar heating applications

    SciTech Connect

    Gibbs, B.M.; Hasnain, S.M.

    1995-11-01

    Differential scanning calorimetry (DSC) was used to investigate the behavior of storage materials that undergo solid-liquid phase transitions. Heating scans were used to measure the enthalpy that can be stored and cooling scans were used to estimate the magnitude of the enthalpy that may be recovered from the storage material. The automatic and rapid thermal cycling features of the DSC system were used to study thermal decomposition that may arise from the daily duty cycle of the storage medium. In this study, DSC methods were applied to technical grade paraffin wax, calcium chloride hexahydrate and disodium hydrogen phosphate dodecahydrate. In the case of inorganic salt hydrates, DSC measurements showed a decrease in heat of fusion; thermal cycling and thermograms revealed considerable super cooling. This would lead to a reduction in storage capacity. On the other hand paraffin wax did not supercool nor were there any indications that thermal cycling or contact with metal could degrade its thermal performance.

  7. Rapid characterization of folding and binding interactions with thermolabile ligands by DSC.

    PubMed

    Harkness, R W; Slavkovic, S; Johnson, P E; Mittermaier, A K

    2016-11-10

    Differential scanning calorimetry (DSC) is a powerful technique for measuring tight biomolecular interactions. However, many pharmaceutically relevant ligands are chemically unstable at the high temperatures used in DSC analyses. Thus, measuring binding interactions is challenging because the concentrations of ligands and thermally-converted products are constantly changing within the calorimeter cell. Using experimental data for two DNA aptamers that bind to the thermolabile ligand cocaine, we present a new global fitting analysis that yields the complete set of folding and binding parameters for the initial and final forms of the ligand from a pair of DSC experiments, while accounting for the thermal conversion. Furthermore, we show that the rate constant for thermolabile ligand conversion may be obtained with only one additional DSC dataset.

  8. Changes of multi-scale structure during mimicked DSC heating reveal the nature of starch gelatinization

    PubMed Central

    Wang, Shujun; Zhang, Xiu; Wang, Shuo; Copeland, Les

    2016-01-01

    A thorough understanding of starch gelatinization is extremely important for precise control of starch functional properties for food processing and human nutrition. Here we reveal the molecular mechanism of starch gelatinization by differential scanning calorimetry (DSC) in conjunction with a protocol using the rapid viscosity analyzer (RVA) to generate material for analysis under conditions that simulated the DSC heating profiles. The results from DSC, FTIR, Raman, X-ray diffraction and small angle X-ray scattering (SAXS) analyses all showed that residual structural order remained in starch that was heated to the DSC endotherm end temperature in starch:water mixtures of 0.5 to 4:1 (v/w). We conclude from this study that the DSC endotherm of starch at a water:starch ratio of 2 to 4 (v/w) does not represent complete starch gelatinization. The DSC endotherm of starch involves not only the water uptake and swelling of amorphous regions, but also the melting of starch crystallites. PMID:27319782

  9. Changes of multi-scale structure during mimicked DSC heating reveal the nature of starch gelatinization.

    PubMed

    Wang, Shujun; Zhang, Xiu; Wang, Shuo; Copeland, Les

    2016-06-20

    A thorough understanding of starch gelatinization is extremely important for precise control of starch functional properties for food processing and human nutrition. Here we reveal the molecular mechanism of starch gelatinization by differential scanning calorimetry (DSC) in conjunction with a protocol using the rapid viscosity analyzer (RVA) to generate material for analysis under conditions that simulated the DSC heating profiles. The results from DSC, FTIR, Raman, X-ray diffraction and small angle X-ray scattering (SAXS) analyses all showed that residual structural order remained in starch that was heated to the DSC endotherm end temperature in starch:water mixtures of 0.5 to 4:1 (v/w). We conclude from this study that the DSC endotherm of starch at a water:starch ratio of 2 to 4 (v/w) does not represent complete starch gelatinization. The DSC endotherm of starch involves not only the water uptake and swelling of amorphous regions, but also the melting of starch crystallites.

  10. Recent advances and potential applications of modulated differential scanning calorimetry (mDSC) in drug development.

    PubMed

    Knopp, Matthias Manne; Löbmann, Korbinian; Elder, David P; Rades, Thomas; Holm, René

    2016-05-25

    Differential scanning calorimetry (DSC) is frequently the thermal analysis technique of choice within preformulation and formulation sciences because of its ability to provide detailed information about both the physical and energetic properties of a substance and/or formulation. However, conventional DSC has shortcomings with respect to weak transitions and overlapping events, which could be solved by the use of the more sophisticated modulated DSC (mDSC). mDSC has multiple potential applications within the pharmaceutical field and the present review provides an up-to-date overview of these applications. It is aimed to serve as a broad introduction to newcomers, and also as a valuable reference for those already practising in the field. Complex mDSC was introduced more than two decades ago and has been an important tool for the quantification of amorphous materials and development of freeze-dried formulations. However, as discussed in the present review, a number of other potential applications could also be relevant for the pharmaceutical scientist.

  11. Changes of multi-scale structure during mimicked DSC heating reveal the nature of starch gelatinization

    NASA Astrophysics Data System (ADS)

    Wang, Shujun; Zhang, Xiu; Wang, Shuo; Copeland, Les

    2016-06-01

    A thorough understanding of starch gelatinization is extremely important for precise control of starch functional properties for food processing and human nutrition. Here we reveal the molecular mechanism of starch gelatinization by differential scanning calorimetry (DSC) in conjunction with a protocol using the rapid viscosity analyzer (RVA) to generate material for analysis under conditions that simulated the DSC heating profiles. The results from DSC, FTIR, Raman, X-ray diffraction and small angle X-ray scattering (SAXS) analyses all showed that residual structural order remained in starch that was heated to the DSC endotherm end temperature in starch:water mixtures of 0.5 to 4:1 (v/w). We conclude from this study that the DSC endotherm of starch at a water:starch ratio of 2 to 4 (v/w) does not represent complete starch gelatinization. The DSC endotherm of starch involves not only the water uptake and swelling of amorphous regions, but also the melting of starch crystallites.

  12. Applications of differential scanning calorimetry for thermal stability analysis of proteins: qualification of DSC.

    PubMed

    Wen, Jie; Arthur, Kelly; Chemmalil, Letha; Muzammil, Salman; Gabrielson, John; Jiang, Yijia

    2012-03-01

    Differential scanning calorimetry (DSC) has been used to characterize protein thermal stability, overall conformation, and domain folding integrity by the biopharmaceutical industry. Recently, there have been increased requests from regulatory agencies for the qualification of characterization methods including DSC. Understanding the method precision can help determine what differences between samples are significant and also establish the acceptance criteria for comparability and other characterization studies. In this study, we identify the parameters for the qualification of DSC for thermal stability analysis of proteins. We use these parameters to assess the precision and sensitivity of DSC and demonstrate that DSC is suitable for protein thermal stability analysis for these purposes. Several molecules from different structural families were studied. The experiments and data analyses were performed by different analysts using different instruments at different sites. The results show that the (apparent) thermal transition midpoint (T(m)) values obtained for the same protein by same and different instruments and/or analysts are quite reproducible, and the profile similarity values obtained for the same protein from the same instrument are also high. DSC is an appropriate method for assessing protein thermal stability and conformational changes.

  13. The Effects of Feeding on Hematological and Plasma Biochemical Profiles in Green (Chelonia mydas) and Kemp's Ridley (Lepidochelys kempii) Sea Turtles.

    PubMed

    Anderson, Eric T; Minter, Larry J; Clarke, Elsburgh O; Mroch, Raymond M; Beasley, Jean F; Harms, Craig A

    2011-01-01

    In mammals, lipemic blood from sampling too soon after an animal feeds can have substantial effects on biochemical values. Plasma biochemical values in reptiles may be affected by species, age, season, and nutritional state. However, fasting status is not routinely considered when sampling reptile blood. In this paper, we evaluated 2-hour postprandial blood collection in two sea turtle species to investigate the effects of feeding on hematological and plasma biochemical values. Feeding had no significant effects on hematological values in either species, nor did it have an effect on plasma biochemistry values in Kemp's ridley sea turtles. In postprandial green turtles, total protein, albumin, ALP, AST, ALT, amylase, and cholesterol increased significantly, and chloride decreased significantly. Although statistically significant changes were observed, the median percent differences between pre- and postprandial values did not exceed 10% for any of these analytes and would not likely alter the clinical interpretation.

  14. The sea-finding behavior of hatchling olive ridley sea turtles, Lepidochelys olivacea, at the beach of San Miguel (Costa Rica).

    PubMed

    Stapput, Katrin; Wiltschko, Wolfgang

    2005-05-01

    Newly hatched olive ridley sea turtles (Lepidochelys olivacea) were tested for their directional preferences in a sand-filled circular arena in total darkness. Hatchlings that had crawled about 5 m on the beach, toward the sea preferred the southwesterly direction that would have brought them to the water line, whereas hatchlings that had been denied this experience headed eastward, a direction of unclear origin. These data suggest that a short crawl across the natural beach can set the direction in which the young turtles subsequently move. The crawling experience was sufficient to acquire the compass course that they later follow, probably with the help of a magnetic compass, not only in the water, but already while still on land.

  15. The Effects of Feeding on Hematological and Plasma Biochemical Profiles in Green (Chelonia mydas) and Kemp's Ridley (Lepidochelys kempii) Sea Turtles

    PubMed Central

    Anderson, Eric T.; Minter, Larry J.; Clarke, Elsburgh O.; Mroch, Raymond M.; Beasley, Jean F.; Harms, Craig A.

    2011-01-01

    In mammals, lipemic blood from sampling too soon after an animal feeds can have substantial effects on biochemical values. Plasma biochemical values in reptiles may be affected by species, age, season, and nutritional state. However, fasting status is not routinely considered when sampling reptile blood. In this paper, we evaluated 2-hour postprandial blood collection in two sea turtle species to investigate the effects of feeding on hematological and plasma biochemical values. Feeding had no significant effects on hematological values in either species, nor did it have an effect on plasma biochemistry values in Kemp's ridley sea turtles. In postprandial green turtles, total protein, albumin, ALP, AST, ALT, amylase, and cholesterol increased significantly, and chloride decreased significantly. Although statistically significant changes were observed, the median percent differences between pre- and postprandial values did not exceed 10% for any of these analytes and would not likely alter the clinical interpretation. PMID:21776356

  16. The sea-finding behavior of hatchling olive ridley sea turtles, Lepidochelys olivacea, at the beach of San Miguel (Costa Rica)

    NASA Astrophysics Data System (ADS)

    Stapput, Katrin; Wiltschko, Wolfgang

    2005-05-01

    Newly hatched olive ridley sea turtles (Lepidochelys olivacea) were tested for their directional preferences in a sand-filled circular arena in total darkness. Hatchlings that had crawled about 5 m on the beach, toward the sea preferred the southwesterly direction that would have brought them to the water line, whereas hatchlings that had been denied this experience headed eastward, a direction of unclear origin. These data suggest that a short crawl across the natural beach can set the direction in which the young turtles subsequently move. The crawling experience was sufficient to acquire the compass course that they later follow, probably with the help of a magnetic compass, not only in the water, but already while still on land.

  17. Comparative study of DSC-PWI and 3D-ASL in ischemic stroke patients.

    PubMed

    Zhang, Shui-xia; Yao, Yi-hao; Zhang, Shun; Zhu, Wen-jie; Tang, Xiang-yu; Qin, Yuan-yuan; Zhao, Ling-yun; Liu, Cheng-xia; Zhu, Wen-zhen

    2015-12-01

    The purpose of this study was to quantitatively analyze the relationship between three dimensional arterial spin labeling (3D-ASL) and dynamic susceptibility contrast-enhanced perfusion weighted imaging (DSC-PWI) in ischemic stroke patients. Thirty patients with ischemic stroke were included in this study. All subjects underwent routine magnetic resonance imaging scanning, diffusion weighted imaging (DWI), magnetic resonance angiography (MRA), 3D-ASL and DSC-PWI on a 3.0T MR scanner. Regions of interest (ROIs) were drawn on the cerebral blood flow (CBF) maps (derived from ASL) and multi-parametric DSC perfusion maps, and then, the absolute and relative values of ASL-CBF, DSC-derived CBF, and DSC-derived mean transit time (MTT) were calculated. The relationships between ASL and DSC parameters were analyzed using Pearson's correlation analysis. Receiver operative characteristic (ROC) curves were performed to define the thresholds of relative value of ASL-CBF (rASL) that could best predict DSC-CBF reduction and MTT prolongation. Relative ASL better correlated with CBF and MTT in the anterior circulation with the Pearson correlation coefficients (R) values being 0.611 (P<0.001) and-0.610 (P<0.001) respectively. ROC curves demonstrated that when rASL ≤0.585, the sensitivity, specificity and accuracy for predicting ROIs with rCBF<0.9 were 92.3%, 63.6% and 76.6% respectively. When rASL ≤0.952, the sensitivity, specificity and accuracy for predicting ROIs rMTT>1.0 were 75.7%, 89.2% and 87.8% respectively. ASL-CBF map has better linear correlations with DSC-derived parameters (DSC-CBF and MTT) in anterior circulation in ischemic stroke patients. Additionally, when rASL is lower than 0.585, it could predict DSC-CBF decrease with moderate accuracy. If rASL values range from 0.585 to 0.952, we just speculate the prolonged MTT.

  18. Inter-nesting movements and habitat-use of adult female Kemp’s ridley turtles in the Gulf of Mexico

    PubMed Central

    Hart, Kristen M.; Fujisaki, Ikuko; Bucklin, David; Iverson, Autumn R.; Rubio, Cynthia; Backof, Thomas F.; Burchfield, Patrick M.; de Jesus Gonzales Diaz Miron, Raul; Dutton, Peter H.; Frey, Amy; Peña, Jaime; Gomez Gamez, Daniel; Martinez, Hector J.; Ortiz, Jaime

    2017-01-01

    Species vulnerability is increased when individuals congregate in restricted areas for breeding; yet, breeding habitats are not well defined for many marine species. Identification and quantification of these breeding habitats are essential to effective conservation. Satellite telemetry and switching state-space modeling (SSM) were used to define inter-nesting habitat of endangered Kemp’s ridley turtles (Lepidochelys kempii) in the Gulf of Mexico. Turtles were outfitted with satellite transmitters after nesting at Padre Island National Seashore, Texas, USA, from 1998 through 2013 (n = 60); Rancho Nuevo, Tamaulipas, Mexico, during 2010 and 2011 (n = 11); and Tecolutla, Veracruz, Mexico, during 2012 and 2013 (n = 11). These sites span the range of nearly all nesting by this species. Inter-nesting habitat lies in a narrow band of nearshore western Gulf of Mexico waters in the USA and Mexico, with mean water depth of 14 to 19 m within a mean distance to shore of 6 to 11 km as estimated by 50% kernel density estimate, α-Hull, and minimum convex polygon methodologies. Turtles tracked during the inter-nesting period moved, on average, 17.5 km/day and a mean total distance of 398 km. Mean home ranges occupied were 725 to 2948 km2. Our results indicate that these nearshore western Gulf waters represent critical inter-nesting habitat for this species, where threats such as shrimp trawling and oil and gas platforms also occur. Up to half of all adult female Kemp’s ridleys occupy this habitat for weeks to months during each nesting season. Because inter-nesting habitat for this species is concentrated in nearshore waters of the western Gulf of Mexico in both Mexico and the USA, international collaboration is needed to protect this essential habitat and the turtles occurring within it. PMID:28319178

  19. Inter-nesting movements and habitat-use of adult female Kemp’s ridley turtles in the Gulf of Mexico

    USGS Publications Warehouse

    Shaver, Donna J.; Hart, Kristen M.; Fujisaki, Ikuko; Bucklin, David N.; Iverson, Autumn; Rubio, Cynthia; Backof, Thomas F.; Burchfield, Patrick M.; Gonzales Diaz Miron, Raul de Jesus; Dutton, Peter H.; Frey, Amy; Peña, Jaime; Gamez, Daniel Gomez; Martinez, Hector J.; Ortiz, Jaime

    2017-01-01

    Species vulnerability is increased when individuals congregate in restricted areas for breeding; yet, breeding habitats are not well defined for many marine species. Identification and quantification of these breeding habitats are essential to effective conservation. Satellite telemetry and switching state-space modeling (SSM) were used to define inter-nesting habitat of endangered Kemp’s ridley turtles (Lepidochelys kempii) in the Gulf of Mexico. Turtles were outfitted with satellite transmitters after nesting at Padre Island National Seashore, Texas, USA, from 1998 through 2013 (n = 60); Rancho Nuevo, Tamaulipas, Mexico, during 2010 and 2011 (n = 11); and Tecolutla, Veracruz, Mexico, during 2012 and 2013 (n = 11). These sites span the range of nearly all nesting by this species. Inter-nesting habitat lies in a narrow band of nearshore western Gulf of Mexico waters in the USA and Mexico, with mean water depth of 14 to 19 m within a mean distance to shore of 6 to 11 km as estimated by 50% kernel density estimate, α-Hull, and minimum convex polygon methodologies. Turtles tracked during the inter-nesting period moved, on average, 17.5 km/day and a mean total distance of 398 km. Mean home ranges occupied were 725 to 2948 km2. Our results indicate that these nearshore western Gulf waters represent critical inter-nesting habitat for this species, where threats such as shrimp trawling and oil and gas platforms also occur. Up to half of all adult female Kemp’s ridleys occupy this habitat for weeks to months during each nesting season. Because inter-nesting habitat for this species is concentrated in nearshore waters of the western Gulf of Mexico in both Mexico and the USA, international collaboration is needed to protect this essential habitat and the turtles occurring within it.

  20. Evaluation of integrated Raman-DSC technology in early pharmaceutical development: characterization of polymorphic systems.

    PubMed

    Huang, Jun; Dali, Manisha

    2013-12-01

    Differential Scanning Calorimetry and Raman spectroscopy are both powerful tools used heavily in pharmaceutical development. For many studies such as polymorph characterization these two techniques are complimentary and provide data on different yet important aspects of material properties when combined together. In this work we describe an integrated Raman-DSC technology that simultaneously generates both DSC thermogram and Raman spectra of the pharmaceutical material being studied. The integrated system consists of a DSC with a Raman fiber optic probe inserted right on top of the sample furnace. The technology integrates synchronized Raman acquisition into DSC scan, enabling collection of molecular and structural information coupled with observation of thermal events. We first establish the technology by optimizing the instrumental set-up that offers relatively high-quality results for simultaneous DSC and Raman data collection. We then demonstrate the application of the technology by studying the polymorphs of d-mannitol, a common pharmaceutical excipient and BMS-A, an investigational drug candidate that exhibits multiple coexisting polymorphs. In both cases, the Raman-DSC technology was able to provide valuable information on the process of phase change and polymorph identification. Although similar information may be obtained by using various characterization techniques together, the integrated Raman-DSC indicated special advantages for industrial development such as high efficiency, material sparing and comprehensive data analysis. Moreover the technology provides an alternative to better correlate real-time phase behavior to molecular understanding. The technology thus has the potential to be used for Process Analytical Technology (PAT) purpose.

  1. Endoplasmic Reticulum Exit of Golgi-resident Defective for SREBP Cleavage (Dsc) E3 Ligase Complex Requires Its Activity.

    PubMed

    Raychaudhuri, Sumana; Espenshade, Peter J

    2015-06-05

    Layers of quality control ensure proper protein folding and complex formation prior to exit from the endoplasmic reticulum. The fission yeast Dsc E3 ligase is a Golgi-localized complex required for sterol regulatory element-binding protein (SREBP) transcription factor activation that shows architectural similarity to endoplasmic reticulum-associated degradation E3 ligases. The Dsc E3 ligase consists of five integral membrane proteins (Dsc1-Dsc5) and functionally interacts with the conserved AAA-ATPase Cdc48. Utilizing an in vitro ubiquitination assay, we demonstrated that Dsc1 has ubiquitin E3 ligase activity that requires the E2 ubiquitin-conjugating enzyme Ubc4. Mutations that specifically block Dsc1-Ubc4 interaction prevent SREBP cleavage, indicating that SREBP activation requires Dsc E3 ligase activity. Surprisingly, Golgi localization of the Dsc E3 ligase complex also requires Dsc1 E3 ligase activity. Analysis of Dsc E3 ligase complex formation, glycosylation, and localization indicated that Dsc1 E3 ligase activity is specifically required for endoplasmic reticulum exit of the complex. These results define enzyme activity-dependent sorting as an autoregulatory mechanism for protein trafficking.

  2. Fast-Scan DSC and its role in pharmaceutical physical form characterisation and selection.

    PubMed

    Ford, James L; Mann, Timothy E

    2012-04-01

    Conventional rate Differential Scanning Calorimetry (DSC) has been used for many years as a tool in the analysis of pharmaceutical materials. In recent years an extension of the technique to include fast heating and cooling rates has become more prevalent. Broadly termed Fast-Scan DSC, this review examines the current applications of this technique to the characterisation and selection of pharmaceutical materials. Its increasing use encompasses the characterisation of amorphousness in crystalline materials, the characterisation of polymorphs and polymorphic transitions, the solubility of drugs in polymers, and characterisation of dosage forms. Notwithstanding the advantages of analytical speed in analytical turnover, the review emphasises the advantages of Fast-Scan DSC in its sensitivity which allows the separation of overlapping thermal events, the reduction it provides in degradation during the scanning process and its role in determining solubility in waxy and polymeric based systems. A comparison of the uses of Fast-Scan DSC to modulated DSC techniques and localised thermal analysis is also given.

  3. DSC: software tool for simulation-based design of control strategies applied to wastewater treatment plants.

    PubMed

    Ruano, M V; Ribes, J; Seco, A; Ferrer, J

    2011-01-01

    This paper presents a computer tool called DSC (Simulation based Controllers Design) that enables an easy design of control systems and strategies applied to wastewater treatment plants. Although the control systems are developed and evaluated by simulation, this tool aims to facilitate the direct implementation of the designed control system to the PC of the full-scale WWTP (wastewater treatment plants). The designed control system can be programmed in a dedicated control application and can be connected to either the simulation software or the SCADA of the plant. To this end, the developed DSC incorporates an OPC server (OLE for process control) which facilitates an open-standard communication protocol for different industrial process applications. The potential capabilities of the DSC tool are illustrated through the example of a full-scale application. An aeration control system applied to a nutrient removing WWTP was designed, tuned and evaluated with the DSC tool before its implementation in the full scale plant. The control parameters obtained by simulation were suitable for the full scale plant with only few modifications to improve the control performance. With the DSC tool, the control systems performance can be easily evaluated by simulation. Once developed and tuned by simulation, the control systems can be directly applied to the full-scale WWTP.

  4. Three who made an association: I. Sir William Osler, 1849-1919. II. George Milbry Gould, 1848-1922. III. Margaret Ridley Charlton, 1858-1931 and the founding of the Medical Library Association, Philadelphia, 1898.

    PubMed Central

    Groen, F K

    1998-01-01

    The careers and personalities of the three founders of the Medical Library Association, Sir William Osler, George Milbry Gould, and Margaret Ridley Charlton are outlined, followed by a review of their role in the founding of the association. The career of Sir William Osler is well documented in existing literature, both in medical history and medical librarianship; the biographies of George Milbry Gould and Margaret Ridley Charlton are less known, and this article describes their lives in relation to the founding of the association. The issue of responsibility for the association's founding is explored, and primary recognition is attributed to Margaret Charlton. The author attempts to follow the tradition of Harvey Cushing in his The Life of Sir William Osler in allowing the characters to speak in their own words as much as possible. Images PMID:9578937

  5. Three who made an association: I. Sir William Osler, 1849-1919 II. George Milbry Gould, 1848-1922 III. Margaret Ridley Charlton, 1858-1931 and the founding of the Medical Library Association, Philadelphia, 1898.

    PubMed Central

    Groen, F K

    1996-01-01

    The careers and personalities of the three founders of the Medical Library Association, Sir William Osler, George Milbry Gould, and Margaret Ridley Charlton are outlined, followed by a review of their role in the founding of the association. The career of Sir William Osler is well documented in existing literature, both in medical history and medical librarianship; the biographies of George Milbry Gould and Margaret Ridley Charlton are less known, and this article describes their lives in relation to the founding of the association. The issue of responsibility for the association's founding is explored, and primary recognition is attributed to Margaret Charlton. The author attempts to follow the tradition of Harvey Cushing in his The Life of Sir William Osler in allowing the characters to speak in their own words as much as possible. Images PMID:8883979

  6. Comparative kinetic analysis on thermal degradation of some cephalosporins using TG and DSC data

    PubMed Central

    2013-01-01

    Background The thermal decomposition of cephalexine, cefadroxil and cefoperazone under non-isothermal conditions using the TG, respectively DSC methods, was studied. In case of TG, a hyphenated technique, including EGA, was used. Results The kinetic analysis was performed using the TG and DSC data in air for the first step of cephalosporin’s decomposition at four heating rates. The both TG and DSC data were processed according to an appropriate strategy to the following kinetic methods: Kissinger-Akahira-Sunose, Friedman, and NPK, in order to obtain realistic kinetic parameters, even if the decomposition process is a complex one. The EGA data offer some valuable indications about a possible decomposition mechanism. The obtained data indicate a rather good agreement between the activation energy’s values obtained by different methods, whereas the EGA data and the chemical structures give a possible explanation of the observed differences on the thermal stability. A complete kinetic analysis needs a data processing strategy using two or more methods, but the kinetic methods must also be applied to the different types of experimental data (TG and DSC). Conclusion The simultaneous use of DSC and TG data for the kinetic analysis coupled with evolved gas analysis (EGA) provided us a more complete picture of the degradation of the three cephalosporins. It was possible to estimate kinetic parameters by using three different kinetic methods and this allowed us to compare the Ea values obtained from different experimental data, TG and DSC. The thermodegradation being a complex process, the both differential and integral methods based on the single step hypothesis are inadequate for obtaining believable kinetic parameters. Only the modified NPK method allowed an objective separation of the temperature, respective conversion influence on the reaction rate and in the same time to ascertain the existence of two simultaneous steps. PMID:23594763

  7. One-step Real-time Food Quality Analysis by Simultaneous DSC-FTIR Microspectroscopy.

    PubMed

    Lin, Shan-Yang; Lin, Chih-Cheng

    2016-01-01

    This review discusses an analytical technique that combines differential scanning calorimetry and Fourier-transform infrared (DSC-FTIR) microspectroscopy, which simulates the accelerated stability test and detects decomposition products simultaneously in real time. We show that the DSC-FTIR technique is a fast, simple and powerful analytical tool with applications in food sciences. This technique has been applied successfully to the simultaneous investigation of: encapsulated squid oil stability; the dehydration and intramolecular condensation of sweetener (aspartame); the dehydration, rehydration and solidification of trehalose; and online monitoring of the Maillard reaction for glucose (Glc)/asparagine (Asn) in the solid state. This technique delivers rapid and appropriate interpretations with food science applications.

  8. Determining the main thermodynamic parameters of caffeine melting by means of DSC

    NASA Astrophysics Data System (ADS)

    Agafonova, E. V.; Moshchenskii, Yu. V.; Tkachenko, M. L.

    2012-06-01

    The temperature and enthalpy of the melting of caffeine, which are 235.5 ± 0.1°C and 19.6 ± 0.2 kJ/mol, respectively, are determined by DSC. The melting entropy and the cryoscopic constant of caffeine are calculated.

  9. DSC of human hair: a tool for claim support or incorrect data analysis?

    PubMed

    Popescu, C; Gummer, C

    2016-10-01

    Differential scanning calorimetry (DSC) data are increasingly used to substantiate product claims of hair repair. Decreasing peak temperatures may indicate structural changes and chemical damage. Increasing the DSC, wet peak temperature is, therefore, often considered as proof of hair repair. A detailed understanding of the technique and hair structure indicates that this may not be a sound approach. Surveying the rich literature on the use of dynamic thermal analysis (DTA) and differential scanning calorimetry (DSC) for the analyses of human hair and the effect of cosmetic treatments, we underline some of the problems of hair structure and data interpretation. To overcome some of the difficulties of data interpretation, we advise that DSC acquired data should be supported by other techniques when used for claim substantiation. In this way, one can provide meaningful interpretation of the hair science and robust data for product claims support. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  10. Multispectral Image Compression Based on DSC Combined with CCSDS-IDC

    PubMed Central

    Li, Jin; Xing, Fei; Sun, Ting; You, Zheng

    2014-01-01

    Remote sensing multispectral image compression encoder requires low complexity, high robust, and high performance because it usually works on the satellite where the resources, such as power, memory, and processing capacity, are limited. For multispectral images, the compression algorithms based on 3D transform (like 3D DWT, 3D DCT) are too complex to be implemented in space mission. In this paper, we proposed a compression algorithm based on distributed source coding (DSC) combined with image data compression (IDC) approach recommended by CCSDS for multispectral images, which has low complexity, high robust, and high performance. First, each band is sparsely represented by DWT to obtain wavelet coefficients. Then, the wavelet coefficients are encoded by bit plane encoder (BPE). Finally, the BPE is merged to the DSC strategy of Slepian-Wolf (SW) based on QC-LDPC by deep coupling way to remove the residual redundancy between the adjacent bands. A series of multispectral images is used to test our algorithm. Experimental results show that the proposed DSC combined with the CCSDS-IDC (DSC-CCSDS)-based algorithm has better compression performance than the traditional compression approaches. PMID:25110741

  11. The Outer Halos of Very Massive Galaxies: BCGs and their DSC in the Magneticum Simulations

    NASA Astrophysics Data System (ADS)

    Remus, Rhea-Silvia; Dolag, Klaus; Hoffmann, Tadziu

    2017-09-01

    Recent hydrodynamic cosmological simulations cover volumes up to Gpc^3 and resolve halos across a wide range of masses and environments, from massive galaxy clusters down to normal galaxies, while following a large variety of physical processes (star formation, chemical enrichment, AGN feedback) to allow a self-consistent comparison to observations at multiple wavelengths. Using the Magneticum simulations, we investigate the buildup of the diffuse stellar component (DSC) around massive galaxies within group and cluster environments. The DSC in our simulations reproduces the spatial distribution of the observed intracluster light (ICL) as well as its kinematic properties remarkably well. For galaxy clusters and groups we find that, although the DSC in almost all cases shows a clear separation from the brightest cluster galaxy (BCG) with regard to its dynamic state, the radial stellar density distribution in many halos is often characterized by a single Sersic profile, representing both the BCG component and the DSC, very much in agreement with current observational results. Interestingly, even in those halos that clearly show two components in both the dynamics and the spatial distribution of the stellar component, no correlation between them is evident.

  12. Multispectral image compression based on DSC combined with CCSDS-IDC.

    PubMed

    Li, Jin; Xing, Fei; Sun, Ting; You, Zheng

    2014-01-01

    Remote sensing multispectral image compression encoder requires low complexity, high robust, and high performance because it usually works on the satellite where the resources, such as power, memory, and processing capacity, are limited. For multispectral images, the compression algorithms based on 3D transform (like 3D DWT, 3D DCT) are too complex to be implemented in space mission. In this paper, we proposed a compression algorithm based on distributed source coding (DSC) combined with image data compression (IDC) approach recommended by CCSDS for multispectral images, which has low complexity, high robust, and high performance. First, each band is sparsely represented by DWT to obtain wavelet coefficients. Then, the wavelet coefficients are encoded by bit plane encoder (BPE). Finally, the BPE is merged to the DSC strategy of Slepian-Wolf (SW) based on QC-LDPC by deep coupling way to remove the residual redundancy between the adjacent bands. A series of multispectral images is used to test our algorithm. Experimental results show that the proposed DSC combined with the CCSDS-IDC (DSC-CCSDS)-based algorithm has better compression performance than the traditional compression approaches.

  13. Measuring the glass transition temperature of EPDM roofing materials: Comparison of DMA, TMA, and DSC techniques

    SciTech Connect

    Paroli, R.M.; Penn, J.

    1994-09-01

    Two ethylene-propylene-diene monomer (EPDM) roofing membranes were aged at 100 C for 7 and 28 days. The T{sub g} of these membranes was then determined by dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), and differential scanning calorimetry (DSC) and the results compared. It was found that: (1) T{sub g} data can be obtained easily using the DMA and TMA techniques. The DSC method requires greater care due to the broad step change in the baseline which is associated with heavily plasticized materials. (2) The closest correspondence between techniques was for TMA and DSC (half-height). The latter, within experimental error, yielded the same glass transition temperature before and after heat-aging. (3) The peak maxima associated with tan{delta} and E{double_prime} measurements should be cited with T{sub g} values as significant differences can exist. (4) The T{sub g}(E{double_prime}) values were closer to the T{sub g}(TMA) and T{sub g}(DSC) data than were the T{sub g}(tan{delta}) values. Data obtained at 1 Hz (or possibly less) should be used when making comparisons based on various techniques. An assessment of T{sub g} values indicated that EPDM 112 roofing membrane is more stable than the EPDM 111 membrane. The T{sub g} for EPDM 112 did not change significantly with heat-aging for 28 days at 130 C.

  14. DSC “peak temperature” versus “maximum slope temperature” in determining TSSD temperature

    NASA Astrophysics Data System (ADS)

    Khatamian, D.

    2010-10-01

    One of the concerns of the nuclear industry is the deleterious effect of hydrogen on the structural integrity of the reactor core components due to delayed hydride cracking (DHC). The DHC process occurs when hydrogen concentration exceeds the terminal solid solubility (TSS) in the component. Thus, the accurate knowledge of TSS is necessary to predict the lifetime of the components. Differential scanning calorimetry (DSC) is normally used to measure the hydrogen TSS in zirconium alloys. There is a measurable change in the amount of heat absorbed by the specimen when the hydrides dissolve. The hydride dissolution process does not exhibit a well-defined "sharp" change in the heat-flow signal at the transition temperature. A typical DSC heat-flow curve for hydride dissolution has three definite features; "peak temperature" (PT), "maximum slope temperature" (MST) and "completion temperature". The present investigation aims to identify the part of the heat-flow signal that closely corresponds to the TSS temperature for hydride dissolution ( TTSSD). Coupons were cut from a Zr-2.5Nb specimen, which had been previously hydrided using an electrolytic cell to create a surface hydride layer of ˜20 μm thick on all sides of the specimen. The coupons were then annealed isothermally at various temperatures to establish the TTSSD under equilibrium conditions. Subsequently the hydride layer was removed and the coupons were analyzed for TSSD temperature using DSC. The PT and MST for each DSC run were determined and compared to the annealing temperature of the coupon. The results show that the annealing temperature (the equilibrium TTSSD) is much closer to the DSC PT than any other feature of the heat-flow curve.

  15. Distinct roles of the DmNav and DSC1 channels in the action of DDT and pyrethroids.

    PubMed

    Rinkevich, Frank D; Du, Yuzhe; Tolinski, Josh; Ueda, Atsushi; Wu, Chun-Fang; Zhorov, Boris S; Dong, Ke

    2015-03-01

    Voltage-gated sodium channels (Nav channels) are critical for electrical signaling in the nervous system and are the primary targets of the insecticides DDT and pyrethroids. In Drosophila melanogaster, besides the canonical Nav channel, Para (also called DmNav), there is a sodium channel-like cation channel called DSC1 (Drosophila sodium channel 1). Temperature-sensitive paralytic mutations in DmNav (para(ts)) confer resistance to DDT and pyrethroids, whereas DSC1 knockout flies exhibit enhanced sensitivity to pyrethroids. To further define the roles and interaction of DmNav and DSC1 channels in DDT and pyrethroid neurotoxicology, we generated a DmNav/DSC1 double mutant line by introducing a para(ts1) allele (carrying the I265N mutation) into a DSC1 knockout line. We confirmed that the I265N mutation reduced the sensitivity to two pyrethroids, permethrin and deltamethrin of a DmNav variant expressed in Xenopus oocytes. Computer modeling predicts that the I265N mutation confers pyrethroid resistance by allosterically altering the second pyrethroid receptor site on the DmNav channel. Furthermore, we found that I265N-mediated pyrethroid resistance in para(ts1) mutant flies was almost completely abolished in para(ts1);DSC1(-/-) double mutant flies. Unexpectedly, however, the DSC1 knockout flies were less sensitive to DDT, compared to the control flies (w(1118A)), and the para(ts1);DSC1(-/-) double mutant flies were even more resistant to DDT compared to the DSC1 knockout or para(ts1) mutant. Our findings revealed distinct roles of the DmNav and DSC1 channels in the neurotoxicology of DDT vs. pyrethroids and implicate the exciting possibility of using DSC1 channel blockers or modifiers in the management of pyrethroid resistance.

  16. Distinct Roles of the DmNav and DSC1 Channels in the Action of DDT and Pyrethroids

    PubMed Central

    Rinkevich, Frank D.; Du, Yuzhe; Tolinski, Josh; Ueda, Atsushi; Wu, Chun-Fang; Zhorov, Boris S.; Dong, Ke

    2015-01-01

    Voltage-gated sodium channels (Nav channels) are critical for electrical signaling in the nervous system and are the primary targets of the insecticides DDT and pyrethroids. In Drosophila melanogaster, besides the canonical Nav channel, Para (also called DmNav), there is a sodium channel-like cation channel called DSC1 (Drosophila sodium channel 1). Temperature-sensitive paralytic mutations in DmNav (parats) confer resistance to DDT and pyrethroids, whereas DSC1 knockout flies exhibit enhanced sensitivity to pyrethroids. To further define the roles and interaction of DmNav and DSC1 channels in DDT and pyrethroid neurotoxicology, we generated a DmNav/DSC1 double mutant line by introducing a parats1 allele (carrying the I265N mutation) into a DSC1 knockout line. We confirmed that the I265N mutation reduced the sensitivity to two pyrethroids, permethrin and deltamethrin of a DmNav variant expressed in Xenopus oocytes. Computer modeling predicts that the I265N mutation confers pyrethroid resistance by allosterically altering the second pyrethroid receptor site on the DmNav channel. Furthermore, we found that I265N-mediated pyrethroid resistance in parats1 mutant flies was almost completely abolished in parats1;DSC1−/− double mutant flies. Unexpectedly, however, the DSC1 knockout flies were less sensitive to DDT, compared to the control flies (w1118A), and the parats1;DSC1−/− double mutant flies were even more resistant to DDT compared to the DSC1 knockout or parats1 mutant. Our findings revealed distinct roles of the DmNav and DSC1 channels in the neurotoxicology of DDT vs. pyrethroids and implicate the exciting possibility of using DSC1 channel blockers or modifiers in the management of pyrethroid resistance. PMID:25687544

  17. δ13C and d15N in the endangered Kemp’s ridley sea turtle Lepidochelys kempii after the Deepwater Horizon oil spill

    USGS Publications Warehouse

    Reich, Kimberly J.; López-Castro, Melania C.; Shaver, Donna J.; Iseton, Claire; Hart, Kristen M.; Hooper, Michael J.; Schmitt, Christopher J.

    2017-01-01

    The Deepwater Horizon explosion in April 2010 and subsequent oil spill released 3.19 × 106 barrels (5.07 × 108 L) of MC252 crude oil into important foraging areas of the endangered Kemp’s ridley sea turtle Lepidochelys kempii (Lk) in the northern Gulf of Mexico (GoM). We measured δ13C and δ15N in scute biopsy samples from 33 Lk nesting in Texas during 2010–-12. Of these, 27 were equipped with satellite transmitters and were tracked to traditional foraging areas in the northern GoM after the spill. Differences in δ13C between the oldest and newest scute layers from 2010 nesters were not significantly different, but δ13C in the newest layers from 2011 and 2012 nesters was significantly lower compared to 2010. δ15N differences were not statistically significant. Collectively, the stable isotope and tracking data indicate that the lower δ13C values reflect the incorporation of oil rather than changes in diet or foraging area. Discriminant analysis indicated that 51.5% of the turtles sampled had isotope signatures indicating oil exposure. Growth of the Lk population slowed in the years following the spill. The involvement of oil exposure in recent population trends is unknown, but long-term effects may not be evident for many years. Our results indicate that C isotope signatures in scutes may be useful biomarkers of sea turtle exposure to oil.

  18. Pathologic and parasitologic findings of cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii) stranded on Cape Cod, Massachusetts, 2001-2006.

    PubMed

    Innis, Charles; Nyaoke, Akinyi C; Williams, C Rogers; Dunnigan, Bridget; Merigo, Constance; Woodward, Denise L; Weber, E Scott; Frasca, Salvatore

    2009-07-01

    Necropsy reports for 28 stranded, cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii) that died between 2001 and 2006 were reviewed retrospectively. Gross and microscopic lesions were compiled to describe the pathologic and parasitologic findings in turtles that were found freshly dead on the beach or that died within 48 hr of stranding. Anatomic lesions of varying severity were identified in each of the examined turtles and were identified in tissues of the alimentary, respiratory, integumentary, nervous and sensory, and urogenital systems in order of decreasing frequency. Necrotizing enterocolitis and bacterial or fungal pneumonia were the most frequently encountered lesions that were considered clinically significant. Parasites and parasitic lesions were identified primarily in tissues of the alimentary system and included intestinal cestodiasis and parasitic granulomas containing larval cestodes or nematodes. Postlarval cestodes were also found in the coelom of two turtles. In many cases, the extent and severity of lesions were judged to be insufficient to have solely caused mortality, suggesting that additional factors such as metabolic, respiratory, and electrolyte derangements; hypothermia; and drowning may be important proximate causes of death in cold-stunned turtles. Results of this study provide insight into pathologic conditions that may be of clinical relevance to rehabilitation efforts for cold-stunned sea turtles.

  19. DSC characterization of ion beam modifications in ion conducting PEO salt polymers

    NASA Astrophysics Data System (ADS)

    Maitra, Minakshi; Verma, K. C.; Sinha, Mrinal; Kumar, Rajesh; Middya, T. R.; Tarafdar, S.; Sen, P.; Bandyopadhyay, S. K.; De, Udayan

    2006-03-01

    Ion conducting polymer films have been prepared by complexing non-conducting poly-(ethylene-oxide), PEO, with x fraction of NH4ClO4 salt. Since its electrical conductivity showed a maximum at x somewhere between 0.18 and 0.19, such polymer films having 17 and 19 wt% salt, have been chosen and irradiated by 160 MeV Ne6+ beam. The films have been investigated by differential scanning calorimetry (DSC) and ac impedance spectroscopy before and after the irradiations. Irradiation-induced shift of an endotherm in our DSC indicates a rise in the melting temperature from 54.6 °C to 57.9 °C for the 19% film. Cross-linking by the Ne-irradiation making the polymer structure more rigid can explain this as well as our other observation of a decrease in electrical conductivity.

  20. Characterization of the polycaprolactone melt crystallization: complementary optical microscopy, DSC, and AFM studies.

    PubMed

    Speranza, V; Sorrentino, A; De Santis, F; Pantani, R

    2014-01-01

    The first stages of the crystallization of polycaprolactone (PCL) were studied using several techniques. The crystallization exotherms measured by differential scanning calorimetry (DSC) were analyzed and compared with results obtained by polarized optical microscopy (POM), rheology, and atomic force microscope (AFM). The experimental results suggest a strong influence of the observation scale. In particular, the AFM, even if limited on time scale, appears to be the most sensitive technique to detect the first stages of crystallization. On the contrary, at least in the case analysed in this work, rheology appears to be the least sensitive technique. DSC and POM provide closer results. This suggests that the definition of induction time in the polymer crystallization is a vague concept that, in any case, requires the definition of the technique used for its characterization.

  1. Psychometric evaluation of the Diabetes Symptom Checklist-Revised (DSC-R)--a measure of symptom distress.

    PubMed

    Arbuckle, Robert A; Humphrey, Louise; Vardeva, Kawitha; Arondekar, Bhakti; Danten-Viala, Muriel; Scott, Jane A; Snoek, Frank J

    2009-01-01

    To assess the psychometric validity, reliability, responsiveness, and minimal important differences of the Diabetes Symptoms Checklist-Revised (DSC-R), a widely used patient-reported outcome measure of diabetes symptom distress. Psychometric validity of the DSC-R was assessed using blinded data from a large-scale trial of approximately 4000 type 2 diabetes patients. Confirmatory factorial analysis (CFA) and multitrait analysis were used to examine the construct validity of the structure of DSC-R. DSC-R internal consistency, discriminative validity, and responsiveness were also assessed. Distribution and anchor-based methods were used to estimate minimal important differences for DSC-R domains. Mean age of the sample was 56 years, 42% were female, 88% were Caucasian. Patients had a mean body mass index (BMI) of 32.2 and mean glucose-fasting level of 151.7 md/dl. CFA and multitrait analysis indicated that the scoring of the DSC-R has acceptable construct validity. Item-scale correlations ranged from 0.44 to 0.78. Cronbach's alpha coefficients ranged from 0.69 to 0.87. At baseline, DSC-R scores were higher among patients with higher BMI scores (P < 0.0001), supporting the discriminative validity of the DSC-R. Minimal important difference estimates ranged from 0.39 to 0.60 points when using distribution methods and from 0.00 to 0.33 when estimated using anchor-based methods. The DSC-R demonstrated excellent psychometric properties when tested in a large-scale diabetes clinical trial. Responsiveness and test-retest reliability of the DSC-R warrant further evaluation.

  2. Toxoplasmosis versus lymphoma: Cerebral lesion characterization using DSC-MRI revisited.

    PubMed

    Dibble, Elizabeth H; Boxerman, Jerrold L; Baird, Grayson L; Donahue, John E; Rogg, Jeffrey M

    2017-01-01

    CNS toxoplasmosis and lymphoma are often indistinguishable by conventional contrast-enhanced MRI. There is limited literature on the diagnostic efficacy of dynamic susceptibility contrast (DSC) MRI for differentiating these entities. This study assesses the clinical utility of relative cerebral blood volume (rCBV) for making a diagnosis and determines rCBV thresholds for differentiation using contemporary DSC-MRI. Thirteen patients with 25 lesions (13 toxoplasmosis and 12 lymphoma) and pre-treatment DSC-MRI were identified retrospectively. Volumetric regions of interest of segmented enhancement were used to extract mean rCBV normalized to normal-appearing white matter for each lesion. We compared average mean rCBV between all toxoplasmosis and lymphoma lesions using a general mixed model. Three models were also compared for evaluating rCBV-based disease status in each patient: 1) mean rCBV of each lesion using a generalized estimating equation, 2) volume-weighted mean rCBV, and 3) maximum mean rCBV of all lesions using logistic regression. The average mean rCBV for all toxoplasmosis lesions was 0.98 (95% CI 0.55-1.41) compared to 2.07 (95% CI 1.71-2.43) for all lymphoma lesions, a significant difference (1.09, 95% CI 0.53-1.65, p=0.0013). For the three models used to evaluate rCBV-based disease status in each patient, a significant relationship was observed, with an optimal rCBV threshold of approximately 1.5 for distinguishing lymphoma from toxoplasmosis in each model. RCBV derived from contemporary DSC-MRI is helpful for distinguishing between cerebral toxoplasmosis and cerebral lymphoma on an individual patient basis and may facilitate more timely initiation of appropriate directed therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Brain Metastases from Different Primary Carcinomas: an Evaluation of DSC MRI Measurements.

    PubMed

    Zhang, H; Zhang, G; Oudkerk, M

    2012-03-01

    This study evaluated the roles of different dynamic susceptibility contrast magnetic imaging (DSC MRI) measurements in discriminating between brain metastases derived from four common primary carcinomas. Thirty-seven patients with brain metastases were enrolled. Relative cerebral blood volume (rCBV), cerebral blood flow (rCBF) and relative mean transit time (rMTT) in both tumor and peritumoral edema were measured. Metastases were grouped by their primary tumor (lung, gastrointestinal, breast and renal cell carcinoma). DSC MRI measurements were compared between groups. Mean rCBV, rCBF, rMTT in tumor and peritumoral edema of all brain metastases (n=37) were 2.79 ± 1.73, 2.56 ± 2.11, 1.21 ± 0.48 and 1.05 ± 0.53, 0.86 ± 0.40, 1.99 ± 0.41, respectively. The tumoral rCBV (5.26 ± 1.89) and rCBF (5.32 ± 3.28) of renal metastases were greater than those of the other three metastases (P<0.05). The tumoral rMTT (1.58 ± 0.77) of breast metastases was statistically greater than that (0.96 ± 0.31) of gastrointestinal metastases (P=0.013). No statistical difference was found between peritumoral rCBV, rCBF and rMTT (P>0.05). Evaluating various DSC MRI measurements can provide complementary hemodynamic information on brain metastases. The tumoral rCBV, rCBF and likely rMTT can help discriminate between brain metastases originating from different primary carcinomas. The peritumoral DSC MRI measurements had limited value in discriminating between brain metastases.

  4. CSL/DSC lattice model for general crystal-crystal boundaries and their line defects

    SciTech Connect

    Balluffi, R.W.; Brokman, A.; King, A.H.

    1981-12-01

    The general CSL/DSC Lattice model for internal boundaries in crystalline materials is described. The model is essentially a fit-misfit model in which the regions of fit are patches where partial lattice matching across the boundary is achieved, and the regions of misfit are boundary line defects possessing dislocation/boundary step character. The degree of fit is effectively measured by the size of an appropriately chosen Coincidence Site Lattice (CSL) formed by the two lattices adjoining the boundary. The Burgers vectors of the line defects are vectors of an appropriately chosen DSC Lattice also formed by the two lattices adjoining the boundary, while the step vectors describing the step character are defined within the framework of the DSC Lattice. The model is extremely general and may be applied to grain boundaries in both cubic and non-cubic materials and interphase boundaries. Applications of the model to a variety of experimental results involving grain boundaries and interphase boundaries are discussed. Some general assessment of the current status of the model is attempted.

  5. CSL/DSC lattice model for general crystal boundaries and their line defects

    SciTech Connect

    Balluffi, R.W.; Brokman, A.; King, A.H.

    1982-08-01

    The general CSL/DSC Lattice model for internal boundaries in crystalline materials is described. The model is essentially a 'fit-misfit' model in which the regions of 'fit' are patches where partial lattice matching across the boundary is achieved and the regions of 'misfit' are boundary line defects possessing dislocation/boundary step character. The degree of 'fit' is effectively measured by the size of an appropriately chosen coincidence site lattice (CSL) formed by the two lattices adjoining the boundary. The Burgers vectors of the line defects are vectors of an appropriately chosen DSC Lattice also formed by the two lattices adjoining the boundary, while the step vectors describing the step character are defined within the framework of the DSC Lattice. The model is extremely general and may be applied to grain boundaries in both cubic and non-cubic materials and interphase boundaries. Applications of the model to a variety of experimental results involving grain boundaries and interphase boundaries are discussed. Some general assessment of the current status of the model is attempted.

  6. DMSO produces a new subgel phase in DPPC: DSC and X-ray diffraction study.

    PubMed

    Tristram-Nagle, S; Moore, T; Petrache, H I; Nagle, J F

    1998-02-02

    Equilibrium phases and the kinetics of subgel phase transformation of dipalmitoylphosphatidylcholine (DPPC) hydrated with mixtures of dimethylsulfoxide (DMSO)/water have been studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The rate of gel-to-subgel transformation is decreased with a small increase in X, the DMSO/water mole fraction, but then speeds up and becomes faster than in pure water by X = 0.16. The DSC scans show multiple subgel peaks, some of which can be attributed to impacted domain growth. For X greater than 0.10, XRD shows that there is a new, stable subgel phase, S, which also accounts for some of the multiplicity of DSC peaks. Our electron density profiles show that the thickness of the bilayer in the S phase is greater than in the usual C subgel phase. We suggest that the S subgel phase is characterized by different headgroup ordering and smaller chain tilt angle than in the C subgel phase. Electron density profiles show that increasing X decreases the water space between bilayers in all phases, subgel, gel and fluid (L alpha). For X = 0.20, a different gel phase is also observed that may be due to subtle changes in the orientation of chain tilt first observed in partially dehydrated DMPC. The dehydrating effect of DMSO explains the results of a previous study, confirmed in this study, that increasing the concentration of DMSO raises the main transition temperature and eliminates the ripple phase.

  7. Non-linear dynamics of the wall touching kink mode and Hiro current simulation with DSC

    NASA Astrophysics Data System (ADS)

    Galkin, S. A.; Svidzinski, V. A.; Evstatiev, E. G.; Zakharov, L. E.

    2011-10-01

    The Disruption Simulation Code (DSC) was initially implemented in 2D (single helicity) with all basic MHD components of the full 3D version. It performs adaptive, meshless free-boundary ideal one-fluid MHD simulations of plasma separated from conducting in-vessel structures by a vacuum region. Vacuum fields, the plasma surface and wall currents are calculated using both Green's functions and Poisson equation methods. Two non-linear regimes of the wall touching kink mode were simulated for the first time: (a) a fast ideal MHD regime till the saturation due to excitation of the Hiro currents in a tile covered plasma facing surface, and (b) a slower regime of the current quench due to resistive decay of the Hiro currents. Corresponding sideways forces applied to the plasma facing components and to the vacuum vessel were calculated. Progress on the 3D DSC extension of ideal one fluid MHD is presented. Implementation of the full 3D resistive MHD will be outlined. Together with realistic wall model this will enable DSC to address the MHD issues of the entire disruption problem and to move forward for understanding opportunities for mitigation and prediction of disruptions in ITER. Work is supported by the US DOE SBIR grant.

  8. Comparison of the Degree of Conversion of Resin Based Endodontic Sealers Using the DSC Technique

    PubMed Central

    Cotti, Elisabetta; Scungio, Paola; Dettori, Claudia; Ennas, Guido

    2011-01-01

    Objectives: The aim of this study was to determine the degree of conversion (DC) of three resin based endodontic sealers using the DSC technique. Methods: The sealers tested were: EndoREZ (ER) (Ultradent, South Jordan, UT); EndoREZ with Accelerator (ER+A) (Ultradent, South Jordan, UT); RealSeal (RS) (SybronEndo, Orange, CA). Two LED units were used to activate the sealers: UltraLume LED 5 (Ultradent, South Jordan, UT, USA); Mini LED Satelec (Satelec Acteon Group, Mérignac Cedex, France). Samples of 4.0 mg were analyzed with a DSC 7 calorimeter (Perkin Elmer Inc., Wellesley, MA, US). Each specimen was irradiated by each lamp four times for 20 seconds at an interval of 2 mins, while the DSC 7 recorded the heat flow developed during the treatment. The degree of conversion and the kinetic curves were calculated from the values of heat developed during each polymerization. The data were statistically analysed with a Kruskal-Wallis one-way ANOVA multiple range and Student-Newman-Keuls (SNK) tests at a P value of .05. Results: Statistically significant differences were found in the degree of conversion among the sealers: ER+A showed the highest values with both lamps. Conclusions: The higher polymerization rate in resin sealers is obtained with the addition of a catalyst. PMID:21494378

  9. Estimation of Temperature Range for Cryo Cutting of Frozen Mackerel using DSC

    NASA Astrophysics Data System (ADS)

    Okamoto, Kiyoshi; Hagura, Yoshio; Suzuki, Kanichi

    Frozen mackerel flesh was subjected to measurement of its fracture stress (bending energy) in a low temperature range. The optimum conditions for low temperature cutting, "cryo cutting," were estimated from the results of enthalpy changes measured by a differential scanning calorimeter (DSC). There were two enthalpy changes for gross transition on the DSC chart for mackerel, one was at -63°C to -77°C and the other at -96°C to -112°C. Thus we estimated that mackerel was able to cut by bending below -63°C and that there would be a great decrease in bending energy occurring at around -77°C and -112°C. In testing, there were indeed two great decreases of bending energy for the test pieces of mackerel that had been frozen at -40°C, one was at -70°C to -90°C and the other was at -100°C to -120°C. Therefore, the test pieces of mackerel could be cut by bending at -70°C. The results showed that the DSC measurement of mackerel flesh gave a good estimation of the appropriate cutting temperature of mackerel.

  10. The potential of high speed DSC (hyper-DSC) for the detection and quantification of small amounts of amorphous content in predominantly crystalline samples.

    PubMed

    Saunders, Mark; Podluii, Kalyan; Shergill, Sukhraj; Buckton, Graham; Royall, Paul

    2004-04-15

    The purpose of this study was to explore whether it is possible to use hyper differential scanning calorimetry (HDSC) to detect and quantify low levels of amorphous content in samples that are mostly crystalline. HDSC uses scan rates that are much faster than conventional DSC, and consequently results in greater sensitivity. It was found that with every increase in scan rate it became easier to detect the glass transition (Tg) response. Scanning at 500 degrees C/min was possible and this gave such great sensitivity that very low sample mass (ca. 1 mg) could be used without any loss in detection of Tg. Mixtures of crystalline and amorphous (spray dried) lactose were prepared and scanned at 500 degrees C/min. It was observed that the Tg response was easily detected even for samples that contained 1.5% amorphous content when using very low samples mass. The view held at present is that DSC is not well suited to studies of amorphous content if the sample contains 10% or less of the amorphous material. The data generated here show that much better detection sensitivity is possible when using the rapid scan rates. As well as being able to detect the presence of very low amorphous contents it was also possible to obtain a quantification, as a linear response was obtained for the step height change in heat flow as a function of amorphous content. It was concluded that HDSC provides a method of obtaining a very fast assessment of the presence of amorphous form, the possibility to quantify this and the need to use a very low sample mass. The combination of speed, low sample mass and sensitivity makes this a very valuable technique for studies on partially amorphous samples.

  11. Yeast sterol regulatory element-binding protein (SREBP) cleavage requires Cdc48 and Dsc5, a ubiquitin regulatory X domain-containing subunit of the Golgi Dsc E3 ligase.

    PubMed

    Stewart, Emerson V; Lloyd, S Julie-Ann; Burg, John S; Nwosu, Christine C; Lintner, Robert E; Daza, Riza; Russ, Carsten; Ponchner, Karen; Nusbaum, Chad; Espenshade, Peter J

    2012-01-02

    Schizosaccharomyces pombe Sre1 is a membrane-bound transcription factor that controls adaptation to hypoxia. Like its mammalian homolog, sterol regulatory element-binding protein (SREBP), Sre1 activation requires release from the membrane. However, in fission yeast, this release occurs through a strikingly different mechanism that requires the Golgi Dsc E3 ubiquitin ligase complex and the proteasome. The mechanistic details of Sre1 cleavage, including the link between the Dsc E3 ligase complex and proteasome, are not well understood. Here, we present results of a genetic selection designed to identify additional components required for Sre1 cleavage. From the selection, we identified two new components of the fission yeast SREBP pathway: Dsc5 and Cdc48. The AAA (ATPase associated with diverse cellular activities) ATPase Cdc48 and Dsc5, a ubiquitin regulatory X domain-containing protein, interact with known Dsc complex components and are required for SREBP cleavage. These findings provide a mechanistic link between the Dsc E3 ligase complex and the proteasome in SREBP cleavage and add to a growing list of similarities between the Dsc E3 ligase and membrane E3 ligases involved in endoplasmic reticulum-associated degradation.

  12. Subunit architecture of the Golgi Dsc E3 ligase required for sterol regulatory element-binding protein (SREBP) cleavage in fission yeast.

    PubMed

    Lloyd, S Julie-Ann; Raychaudhuri, Sumana; Espenshade, Peter J

    2013-07-19

    The membrane-bound sterol regulatory element-binding protein (SREBP) transcription factors regulate lipogenesis in mammalian cells and are activated through sequential cleavage by the Golgi-localized Site-1 and Site-2 proteases. The mechanism of fission yeast SREBP cleavage is less well defined and, in contrast, requires the Golgi-localized Dsc E3 ligase complex. The Dsc E3 ligase consists of five integral membrane subunits, Dsc1 through Dsc5, and resembles membrane E3 ligases that function in endoplasmic reticulum-associated degradation. Using immunoprecipitation assays and blue native electrophoresis, we determined the subunit architecture for the complex of Dsc1 through Dsc5, showing that the Dsc proteins form subcomplexes and display defined connectivity. Dsc2 is a rhomboid pseudoprotease family member homologous to mammalian UBAC2 and a central component of the Dsc E3 ligase. We identified conservation in the architecture of the Dsc E3 ligase and the multisubunit E3 ligase gp78 in mammals. Specifically, Dsc1-Dsc2-Dsc5 forms a complex resembling gp78-UBAC2-UBXD8. Further characterization of Dsc2 revealed that its C-terminal UBA domain can bind to ubiquitin chains but that the Dsc2 UBA domain is not essential for yeast SREBP cleavage. Based on the ability of rhomboid superfamily members to bind transmembrane proteins, we speculate that Dsc2 functions in SREBP recognition and binding. Homologs of Dsc1 through Dsc4 are required for SREBP cleavage and virulence in the human opportunistic pathogen Aspergillus fumigatus. Thus, these studies advance our organizational understanding of multisubunit E3 ligases involved in endoplasmic reticulum-associated degradation and fungal pathogenesis.

  13. Expression of aromatase in the embryonic brain of the olive ridley sea turtle (Lepidochelys olivacea), and the effect of bisphenol-A in sexually differentiated embryos.

    PubMed

    Gómez-Picos, Patsy; Sifuentes-Romero, Itzel; Merchant-Larios, Horacio; Hernández-Cornejo, Rubí; Díaz-Hernández, Verónica; García-Gasca, Alejandra

    2014-01-01

    Brain aromatase participates in several biological processes, such as regulation of the reproductive-endocrine axis, memory, stress, sexual differentiation of the nervous system, male sexual behavior, and brain repair. Here we report the isolation and expression of brain aromatase in olive ridley sea turtle (Lepidochelys olivacea) embryos incubated at male- and female-promoting temperatures (MPT and FPT, respectively), at the thermosensitive period (TSP) and the sex-differentiated period. Also, aromatase expression was assessed in differentiated embryos exposed to bisphenol-A (BPA) during the TSP. BPA is a monomer of polycarbonate plastics and is considered an endocrine-disrupting compound. Normal aromatase expression was measured in both forebrain and hindbrain, showing higher expression levels in the forebrain of differentiated embryos at both incubation temperatures. Although no significant differences were detected in the hindbrain, expression was slightly higher at MPT. BPA did not affect aromatase expression neither in forebrains or hindbrains from embryos incubated at MPT, whereas at FPT an inverted U-shape curve was observed in forebrains with significant differences at lower concentrations, whereas in hindbrains a non-significant increment was observed at higher concentrations. Our data indicate that both incubation temperature and developmental stage are critical factors affecting aromatase expression in the forebrain. Because of the timing and location of aromatase expression in the brain, we suggest that brain aromatase may participate in the imprinting of sexual trends related to reproduction and sexual behavior at the onset of sex differentiation, and BPA exposure may impair aromatase function in the female forebrain.

  14. Drug-polymer interaction between glucosamine sulfate and alginate nanoparticles: FTIR, DSC and dielectric spectroscopy studies

    NASA Astrophysics Data System (ADS)

    El-Houssiny, A. S.; Ward, A. A.; Mostafa, D. M.; Abd-El-Messieh, S. L.; Abdel-Nour, K. N.; Darwish, M. M.; Khalil, W. A.

    2016-06-01

    This work involves the preparation and characterization of alginate nanoparticles (Alg NPs) as a new transdermal carrier for site particular transport of glucosamine sulfate (GS). The GS-Alg NPs were examined through transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and dielectric spectroscopy. GS-Alg NPs was efficiently prepared via ionic gelation method which generates favorable conditions for the entrapment of hydrophilic drugs. The TEM studies revealed that GS-Alg NPs are discrete and have spherical shapes. FTIR studies showed a spectral change of the characteristic absorptions bands of Alg NPs after encapsulation with GS because of the amine groups of GS and the carboxylic acid groups of Alg. The DSC data showed changes in the thermal behavior of GS-Alg NPs after the addition of GS indicating signs of main chemical interaction among the drug (GS) and the polymer (Alg). The absence of the drug melting endothermic peak within the DSC thermogram of GS-Alg NPs indicating that GS is molecularly dispersed in the NPs and not crystallize. From the dielectric study, it was found modifications within the dielectric loss (ɛ″) and conductivity (σ) values after the addition of GS. The ɛ″ and σ values of Alg NPs decreased after the addition of GS which indicated the successful encapsulation of GS within Alg NPs. Furthermore, the dielectric study indicated an increase of the activation energy and the relaxation time for the first process in the GS-Alg NPs as compared to Alg NPs. Consequently, the existing observations indicated an initiation of electrostatic interaction among the amine group of GS and carboxyl group of Alg indicating the successful encapsulation of GS inside Alg NPs which could provide favorable circumstance for the encapsulation of GS for topical management.

  15. Classification of tumor area using combined DCE and DSC MRI in patients with glioblastoma.

    PubMed

    Artzi, Moran; Blumenthal, Deborah T; Bokstein, Felix; Nadav, Guy; Liberman, Gilad; Aizenstein, Orna; Ben Bashat, Dafna

    2015-01-01

    This study proposes an automatic method for identification and quantification of different tissue components: the non-enhanced infiltrative tumor, vasogenic edema and enhanced tumor areas, at the subject level, in patients with glioblastoma (GB) based on dynamic contrast enhancement (DCE) and dynamic susceptibility contrast (DSC) MRI. Nineteen MR data sets, obtained from 12 patients with GB, were included. Seven patients were scanned before and 8 weeks following bevacizumab initiation. Segmentation of the tumor area was performed based on the temporal data of DCE and DSC at the group-level using k-means algorithm, and further at the subject-level using support vector machines algorithm. The obtained components were associated to different tissues types based on their temporal characteristics, calculated perfusion and permeability values and MR-spectroscopy. The method enabled the segmentation of the tumor area into the enhancing permeable component; the non-enhancing hypoperfused component, associated with vasogenic edema; and the non-enhancing hyperperfused component, associated with infiltrative tumor. Good agreement was obtained between the group-level, unsupervised and subject-level, supervised classification results, with significant correlation (r = 0.93, p < 0.001) and average symmetric root-mean-square surface distance of 2.5 ± 5.1 mm. Longitudinal changes in the volumes of the three components were assessed alongside therapy. Tumor area segmentation using DCE and DSC can be used to differentiate between vasogenic edema and infiltrative tumors in patients with GB, which is of major clinical importance in therapy response assessment.

  16. Crystallization and glass transition of the diols and aminoalcohols, according to DSC data

    NASA Astrophysics Data System (ADS)

    Solonina, I. A.; Rodnikova, M. N.; Kiselev, M. P.; Khoroshilov, A. V.

    2015-05-01

    Overcooling, crystallization, and glass transition of the diol series and aminoalcohols which are the liquids with spatial hydrogen-bond networks, which are the along with the overcooling of dioxane, dimethylsulfoxide, and acetonitrile, which do not have such networks were studied by DSC. The observed phenomena are explained by the stability of H-bond networks. It was concluded that changes in the stability of the networks in and between series of diols and aminoalcohols are due to differences between their molecular structures, the energies of their hydrogen bonds, and their network topologies.

  17. DSC method: Determination of amorphous fraction in solid dosage and fragility

    NASA Astrophysics Data System (ADS)

    Saini, Manoj K.

    2015-06-01

    We have used Differential Scanning Calorimeter (DSC) method to quantifying the amorphous content in solid dosage of a commonly used drugs namely mephenesin. The glass transition temperature (Tg) of supercooled liquid sample and melting temperature (Tm) of as received sample are found to be 232.2 K and 343.1 K respectively. The "fragility index" of mephenesin has been discussed in detail using the coupling model (m = 250(± 30) - 320βKWW) and compared with acetaminophen and methocarbamol. The sample studied here is found to be kinetically strong in comparison.

  18. Comparison between DSC and TMDSC in the investigation into frozen aqueous cryoprotectants solutions.

    PubMed

    Santoveña, A; Piñero, M J; Llabrés, M

    2010-12-01

    The influence of thermal parameters in the observation of thermal events and in the calculation of heat transformation in aqueous cryoprotectant solutions after freezing was investigated using conventional differential scanning calorimetry (DSC) and temperature-modulated DSC (TMDSC), respectively. The systems under study were formed by pure water and diluted aqueous solutions of mannitol, trehalose, sucrose, sorbitol, and glycine. The influence of different combinations of frequency and amplitude was analyzed in heating-cooling and heating-iso TMDSC scans. Trehalose, sucrose, and sorbitol present a lesser critical temperature of primary drying than other cryoprotectants studied. The calorimetric variables selection is crucial to detect or not the thermal events, or to detect so with different numerical values. Then, the values of the calorimetric parameters determined are different if measured in a mode of heating-cooling or heating-iso. The TMDSC method-1 used in this study employs a higher number of cycles in each thermal event. The use of Lissajous figures and the study of the C(p in-phase) signal evolution will allow us to understand the complexity of the events detected. The comparative study of both techniques points to the selection of conventional or modulated technique depending on the type of system and the nature of the studied events.

  19. Remote Evaluation of Rotational Velocity Using a Quadrant Photo-Detector and a DSC Algorithm

    PubMed Central

    Zeng, Xiangkai; Zhu, Zhixiong; Chen, Yang

    2016-01-01

    This paper presents an approach to remotely evaluate the rotational velocity of a measured object by using a quadrant photo-detector and a differential subtraction correlation (DSC) algorithm. The rotational velocity of a rotating object is determined by two temporal-delay numbers at the minima of two DSCs that are derived from the four output signals of the quadrant photo-detector, and the sign of the calculated rotational velocity directly represents the rotational direction. The DSC algorithm does not require any multiplication operations. Experimental calculations were performed to confirm the proposed evaluation method. The calculated rotational velocity, including its amplitude and direction, showed good agreement with the given one, which had an amplitude error of ~0.3%, and had over 1100 times the efficiency of the traditional cross-correlation method in the case of data number N > 4800. The confirmations have shown that the remote evaluation of rotational velocity can be done without any circular division disk, and that it has much fewer error sources, making it simple, accurate and effective for remotely evaluating rotational velocity. PMID:27120607

  20. Interactions of tamoxifen with distearoyl phosphatidylcholine multilamellar vesicles: FTIR and DSC studies

    NASA Astrophysics Data System (ADS)

    Bilge, Duygu; Sahin, Ipek; Kazanci, Nadide; Severcan, Feride

    2014-09-01

    Interactions of a non-steroidal antiestrogen drug, tamoxifen (TAM), with distearoyl-sn-glycero-3-phosphatidylcholine (DSPC) multilamellar liposomes (MLVs) were investigated as a function of drug concentration (1-15 mol%) by using two noninvasive techniques, namely Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). FTIR spectroscopy results show that increasing TAM concentrations (except 1 mol%) increased the wavenumbers of the CH2 stretching modes, implying an disordering effect for DSPC MLVs both in the gel and liquid crystalline phases. The bandwidth values of the CH2 stretchings except for 1 mol% increased when TAM concentrations increased for DSPC liposomes, indicating an increase in the dynamics of liposomes. The Cdbnd O stretching and PO2- antisymmetric double bond stretching bands were analyzed to study interactions of TAM with head groups of lipids. As the concentrations of TAM increased, dehydration occurred around these functional groups in the polar part of the lipids. The DSC studies on thermal properties of DSPC lipids indicate that TAM eliminated the pre transition, shifted the main phase transition to lower temperatures and broadened the phase transition curve of the liposomes.

  1. Synergistic gel formation of xyloglucan/gellan mixtures as sudied by rheology, DSC, and circular dichroism.

    PubMed

    Nitta, Yoko; Kim, Bo S; Nishinari, Katsuyoshi; Shirakawa, Mayumi; Yamatoya, Kazuhiko; Oomoto, Toshio; Asai, Iwao

    2003-01-01

    The gelation behavior of mixtures of tamarind seed xyloglucan (TSX) and sodium form gellan (Na-G) was investigated. The storage and loss shear moduli, G' and G'', of the mixtures showed that a thermoreversible gel was obtained although each polysaccharide alone did not form a gel at experimental conditions. The viscoelastic behavior of the mixtures showed a gel formation of TSX and Na-G induced by synergistic interaction. This synergistic interaction was also revealed by differential scanning calorimetry (DSC) and circular dichroism. Although TSX alone did not show any peak in DSC curves, mixtures with only a small amount of Na-G, which by itself did not show any peak, showed a single peak. With increasing Na-G content, another peak began to appear at the same temperature at which a peak of Na-G alone appeared. Thermally induced changes in circular dichroism of the mixtures were different from those expected from the individual behavior of TSX and Na-G.

  2. Remote Evaluation of Rotational Velocity Using a Quadrant Photo-Detector and a DSC Algorithm.

    PubMed

    Zeng, Xiangkai; Zhu, Zhixiong; Chen, Yang

    2016-04-25

    This paper presents an approach to remotely evaluate the rotational velocity of a measured object by using a quadrant photo-detector and a differential subtraction correlation (DSC) algorithm. The rotational velocity of a rotating object is determined by two temporal-delay numbers at the minima of two DSCs that are derived from the four output signals of the quadrant photo-detector, and the sign of the calculated rotational velocity directly represents the rotational direction. The DSC algorithm does not require any multiplication operations. Experimental calculations were performed to confirm the proposed evaluation method. The calculated rotational velocity, including its amplitude and direction, showed good agreement with the given one, which had an amplitude error of ~0.3%, and had over 1100 times the efficiency of the traditional cross-correlation method in the case of data number N > 4800. The confirmations have shown that the remote evaluation of rotational velocity can be done without any circular division disk, and that it has much fewer error sources, making it simple, accurate and effective for remotely evaluating rotational velocity.

  3. Effects of annealing on enthalpy relaxation in lyophilized disaccharide formulations: mathematical modeling of DSC curves.

    PubMed

    Luthra, Suman A; Hodge, Ian M; Pikal, Michael J

    2008-08-01

    The overall objective of these studies was to investigate, by experimental studies and theoretical analysis, the optimum annealing conditions to obtain maximum structural relaxation in lyophilized glasses of pharmaceutical significance. The model formulations used in this work were aspartame: sucrose and aspartame: trehalose (1:10 w/w) freeze-dried glasses. In this article, structural relaxation in amorphous systems was described in terms of the change in the fictive temperature (T(f)) and was measured using the enthalpy relaxation endotherm in a differential scanning calorimeter (DSC). The theoretical analysis was performed using the Tool-Narayanaswamy-Moynihan (TNM) model. The effect of different annealing conditions (temperature and time) on fictive temperature obtained from the theoretical analysis was calculated and compared with the experimental results. The model reproduced the experimental data very well for samples that were quench cooled from the liquid. However, the model fits were poor for lyophilized samples, indicating an inability to incorporate the complex thermal history of freeze-drying in the TNM model. The optimum aging conditions were determined from both DSC and approximated best-fit parameters of the TNM model, and it was found that annealing when done at a temperature about 15-25 degrees C below T(g) resulted in maximum structural relaxation.

  4. Thermal stability of porcine pepsin influenced by Al(III) ion: DSC study

    NASA Astrophysics Data System (ADS)

    Pavelkić, V. M.; Beljanski, M. V.; Antić, K. M.; Babić, M. M.; Brdarić, T. P.; Gopčević, K. R.

    2011-12-01

    Differential scanning calorimetry (DCS) has been used to determine thermodynamic profile of pepsin and the in vitro effect of Al(III) ions. Thermograms of pepsin unfolding in the presence and absence of aluminum were used to determine the binding constant, K L, in the pepsin-aluminium model system. The thermodynamic parameters were derived from DSC profiles at different ligand concentrations (1, 5 and 10 mM). The temperatures of thermal transitions ( T m), calorimetric (Δ H cal) and van't Hoff enthalpy (Δ H VH), Gibbs free energy, Δ(Δ G), of Al(III) binding to pepsin, as well as an average number of ligands bound to the native protein, were obtained from DSC profiles too. Temperature-dependent changes in the protein structure were also monitored by native PAGE electrophoresis. Increasing the temperature causes the decrease in electrophoretic mobility. Increase in concentration of Al(III) decelerate the migration of pepsin samples on concentration dependent manner. Analysis showed that ligand binding increases thermal stability of protein.

  5. Structure of rat skin after application of electret characterized by DSC

    NASA Astrophysics Data System (ADS)

    Cui, L. L.; Liang, Y. Y.; Dong, F. J.; Ma, L.; Tu, Y.; Liu, H. Y.; Jiang, J.

    2011-06-01

    Polypropylene (PP) electrets with surface potential of -500V, -1000V and -2000V were prepared by constant voltage corona charging. The electrets were applied to excised rat skin for 2 hours respectively and then the skin samples were analyzed with the differential scanning calorimetry (DSC) technique to study the alteration of lipid organization of the skin. There were three peaks at 63°C, 82.7°C and 115.1°C in the DSC spectra for rat skin untreated, which have been assigned essentially to lipid, lipid-protein and protein alterations. For -500V electret treated-skin sample, only a single peak appeared at 79.1°C. With the increase of electret surface potential from -500V to -2000V, the transition temperature and peak areas at moderate decreased first and then increased. The negative electret could result in the transition of stratum corneum (SC) lipid from gel to liquid crystal and protein transition from α helix structure to β folding structure. The regulation action of electret to skin mircostructure presented an effect of "potential window".

  6. Investigation of MSWI fly ash melting characteristic by DSC-DTA.

    PubMed

    Li, Rundong; Wang, Lei; Yang, Tianhua; Raninger, Bernhard

    2007-01-01

    The melting process of MSWI (Municipal Solid Waste Incineration) fly ash has been studied by high-temperature DSC-DTA experiments. The experiments were performed at a temperature range of 20-1450 degrees C, and the considerable variables included atmosphere (O(2) and N(2)), heating rates (5 degrees C/min, 10 degrees C/min, 20 degrees C/min) and CaO addition. Three main transitions were observed during the melting process of fly ash: dehydration, polymorphic transition and fusion, occurring in the temperature range of 100-200 degrees C, 480-670 degrees C and 1101-1244 degrees C, respectively. The apparent heat capacity and heat requirement for melting of MSWI fly ash were obtained by DSC (Differential Scanning Calorimeter). A thermodynamic modeling to predict the heat requirements for melting process has been presented, and it agrees well with the experimental data. Finally, a zero-order kinetic model of fly ash melting transition was established. The apparent activation energy of MSWI fly ash melting transition was obtained.

  7. Interactions of tamoxifen with distearoyl phosphatidylcholine multilamellar vesicles: FTIR and DSC studies.

    PubMed

    Bilge, Duygu; Sahin, Ipek; Kazanci, Nadide; Severcan, Feride

    2014-09-15

    Interactions of a non-steroidal antiestrogen drug, tamoxifen (TAM), with distearoyl-sn-glycero-3-phosphatidylcholine (DSPC) multilamellar liposomes (MLVs) were investigated as a function of drug concentration (1-15 mol%) by using two noninvasive techniques, namely Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). FTIR spectroscopy results show that increasing TAM concentrations (except 1 mol%) increased the wavenumbers of the CH2 stretching modes, implying an disordering effect for DSPC MLVs both in the gel and liquid crystalline phases. The bandwidth values of the CH2 stretchings except for 1 mol% increased when TAM concentrations increased for DSPC liposomes, indicating an increase in the dynamics of liposomes. The CO stretching and PO2- antisymmetric double bond stretching bands were analyzed to study interactions of TAM with head groups of lipids. As the concentrations of TAM increased, dehydration occurred around these functional groups in the polar part of the lipids. The DSC studies on thermal properties of DSPC lipids indicate that TAM eliminated the pre transition, shifted the main phase transition to lower temperatures and broadened the phase transition curve of the liposomes.

  8. Application of chemometric methods to differential scanning calorimeter (DSC) to estimate nimodipine polymorphs from cosolvent system.

    PubMed

    Siddiqui, Akhtar; Rahman, Ziyaur; Khan, Mansoor A

    2015-06-01

    The focus of this study was to evaluate the applicability of chemometrics to differential scanning calorimetry data (DSC) to evaluate nimodipine polymorphs. Multivariate calibration models were built using DSC data from known mixtures of the nimodipine modification. The linear baseline correction treatment of data was used to reduce dispersion in thermograms. Principal component analysis of the treated and untreated data explained 96% and 89% of the data variability, respectively. Score and loading plots correlated variability between samples with change in proportion of nimodipine modifications. The R(2) for principal component regression (PCR) and partial lease square regression (PLS) were found to be 0.91 and 0.92. The root mean square of standard error of the treated samples for calibration and validation in PCR and PLS was found to be lower than the untreated sample. These models were applied to samples recrystallized from a cosolvent system, which indicated different proportion of modifications in the mixtures than those obtained by placing samples under different storage conditions. The model was able to predict the nimodipine modifications with known margin of error. Therefore, these models can be used as a quality control tool to expediently determine the nimodipine modification in an unknown mixture.

  9. Increased cortical capillary transit time heterogeneity in Alzheimer's disease: a DSC-MRI perfusion study.

    PubMed

    Eskildsen, Simon F; Gyldensted, Louise; Nagenthiraja, Kartheeban; Nielsen, Rune B; Hansen, Mikkel Bo; Dalby, Rikke B; Frandsen, Jesper; Rodell, Anders; Gyldensted, Carsten; Jespersen, Sune N; Lund, Torben E; Mouridsen, Kim; Brændgaard, Hans; Østergaard, Leif

    2017-02-01

    Alzheimer's disease (AD) is characterized by the accumulation of hyperphosphorylated tau and neurotoxic Aβ in the brain parenchyma. Hypoxia caused by microvascular changes and disturbed capillary flows could stimulate this build-up of AD-specific proteins in the brain. In this study, we compared cerebral microcirculation in a cohort of AD and mild cognitive impairment (MCI) patients with that of age-matched controls, all without a history of diabetes or of hypertension for more than 2 years, using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI). Vascular flow disturbances were quantified using a parametric model and mapped to the mid-cortical surface for group-wise statistical analysis. We found widespread hypoperfusion in patients compared with controls and identified areas of increased relative capillary transit time heterogeneity (RTH), consistent with low tissue oxygen tension. Notably, RTH was positively correlated with white matter hyperintensities and positively correlated with symptom severity in the patient cohort. These correlations extended over large parts of the temporal, parietal, and frontal cortices. The results support the hypothesis of disturbed capillary flow patterns in AD and suggest that DSC-MRI may provide imaging biomarkers of impaired cerebral microcirculation in AD.

  10. Decentralized Adaptive Neural Output-Feedback DSC for Switched Large-Scale Nonlinear Systems.

    PubMed

    Long, Lijun; Zhao, Jun

    2016-03-08

    In this paper, for a class of switched large-scale uncertain nonlinear systems with unknown control coefficients and unmeasurable states, a switched-dynamic-surface-based decentralized adaptive neural output-feedback control approach is developed. The approach proposed extends the classical dynamic surface control (DSC) technique for nonswitched version to switched version by designing switched first-order filters, which overcomes the problem of multiple ``explosion of complexity.'' Also, a dual common coordinates transformation of all subsystems is exploited to avoid individual coordinate transformations for subsystems that are required when applying the backstepping recursive design scheme. Nussbaum-type functions are utilized to handle the unknown control coefficients, and a switched neural network observer is constructed to estimate the unmeasurable states. Combining with the average dwell time method and backstepping and the DSC technique, decentralized adaptive neural controllers of subsystems are explicitly designed. It is proved that the approach provided can guarantee the semiglobal uniformly ultimately boundedness for all the signals in the closed-loop system under a class of switching signals with average dwell time, and the tracking errors to a small neighborhood of the origin. A two inverted pendulums system is provided to demonstrate the effectiveness of the method proposed.

  11. Investigation of MSWI fly ash melting characteristic by DSC-DTA

    SciTech Connect

    Li, Rundong Wang, Lei; Yang, Tianhua; Raninger, Bernhard

    2007-07-01

    The melting process of MSWI (Municipal Solid Waste Incineration) fly ash has been studied by high-temperature DSC-DTA experiments. The experiments were performed at a temperature range of 20-1450 deg. C, and the considerable variables included atmosphere (O{sub 2} and N{sub 2}), heating rates (5 deg. C/min, 10 deg. C/min, 20 deg. C/min) and CaO addition. Three main transitions were observed during the melting process of fly ash: dehydration, polymorphic transition and fusion, occurring in the temperature range of 100-200 deg. C, 480-670 deg. C and 1101-1244 deg. C, respectively. The apparent heat capacity and heat requirement for melting of MSWI fly ash were obtained by DSC (Differential Scanning Calorimeter). A thermodynamic modeling to predict the heat requirements for melting process has been presented, and it agrees well with the experimental data. Finally, a zero-order kinetic model of fly ash melting transition was established. The apparent activation energy of MSWI fly ash melting transition was obtained.

  12. Diffusion of liquid polystyrene into glassy poly(phenylene oxide) characterized by DSC

    NASA Astrophysics Data System (ADS)

    Li, Linling; Wang, Xiaoliang; Zhou, Dongshan; Xue, Gi

    2013-03-01

    We report a diffusion study on the polystyrene/poly(phenylene oxide) (PS/PPO) mixture consisted by the PS and PPO nanoparticles. Diffusion of liquid PS into glassy PPO (l-PS/g-PPO) is promoted by annealing the PS/PPO mixture at several temperatures below Tg of the PPO. By tracing the Tgs of the PS-rich domain behind the diffusion front using DSC, we get the relationships of PS weight fractions and diffusion front advances with the elapsed diffusion times at different diffusion temperatures using the Gordon-Taylor equation and core-shell model. We find that the plots of weight fraction of PS vs. elapsed diffusion times at different temperatures can be converted to a master curve by Time-Temperature superposition, and the shift factors obey the Arrhenius equation. Besides, the diffusion front advances of l-PS into g-PPO show an excellent agreement with the t1/2 scaling law at the beginning of the diffusion process, and the diffusion coefficients of different diffusion temperatures also obey the Arrhenius equation. We believe the diffusion mechanism for l-PS/g-PPO should be the Fickean law rather than the Case II, though there are departures of original linearity at longer diffusion times due to the limited liquid supply system. Diffusion of liquid polystyrene into glassy poly(phenylene oxide) characterized by DSC

  13. Multivariate statistical analysis treatment of DSC thermal properties for animal fat adulteration.

    PubMed

    Dahimi, Omar; Rahim, Alina Abdul; Abdulkarim, S M; Hassan, Mohd Sukri; Hashari, Shazamawati B T Zam; Mashitoh, A Siti; Saadi, Sami

    2014-09-01

    The adulteration of edible fats is a kind of fraud that impairs the physical and chemical features of the original lipid materials. It has been detected in various food, pharmaceutical and cosmeceutical products. Differential scanning calorimetry (DSC) is the robust thermo-analytical machine that permits to fingerprint the primary crystallisation of triacylglycerols (TAGs) molecules and their transition behaviours. The aims of this study was to assess the cross-contamination caused by lard concentration of 0.5-5% in the mixture systems containing beef tallow (BT) and chicken fat (CF) separately. TAGs species of pure and adulterated lipids in relation to their crystallisation and melting parameters were studied using principal components analysis (PCA). The results showed that by using the heating profiles the discrimination of LD from BT and CF was very clear even at low dose of less than 1%. Same observation was depicted from the crystallisation profiles of BT adulterated by LD doses ranging from 0.1% to 1% and from 2% to 5%, respectively. Furthermore, CF adulterated with LD did not exhibit clear changes on its crystallisation profiles. Consequently, DSC coupled with PCA is one of the techniques that might use to monitor and differentiate the minimum adulteration levels caused by LD in different animal fats. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Aggregation of bovine insulin probed by DSC/PPC calorimetry and FTIR spectroscopy.

    PubMed

    Dzwolak, Wojciech; Ravindra, Revanur; Lendermann, Julia; Winter, Roland

    2003-09-30

    Pressure perturbation calorimetry (PPC), differential scanning calorimetry (DSC), and time-resolved Fourier transform infrared spectroscopy (FTIR) have been employed to investigate aggregation of bovine insulin at pH 1.9. The aggregation process exhibits two distinguished phases. In the first phase, an intermediate molten globule-like conformational state is transiently formed, reflected by loose tertiary contacts and a robust H/D-exchange. This is followed by unfolding of the native secondary structure. The unfolding of insulin is fast, endothermic, partly reversible, and accompanied by a volume expansion of approximately 0.2%. The second phase consists of actual aggregation: an exothermic irreversible process revealing typical features of nucleation-controlled kinetics. The volumetric changes associated with the second phase are small. The concentration-dependence of DSC scans does not support a monomer intermediate model. While insulin aggregation under ambient pressure is fast and quantitative, pressure as low as 300 bar is sufficient to prevent the aggregation completely, as high-pressure FTIR spectroscopy revealed. This is explained in terms of the high pressure having an adverse effect on the thermal unfolding of insulin, and therefore preventing occurrence of the aggregation-prone intermediate. A comparison of the aggregation in H(2)O and D(2)O shows that the isotopic substitution has diverse effects on both the phases of aggregation. In heavy water, a more pronounced volume expansion accompanies the unfolding stage, while only the second phase shifts to higher temperature.

  15. Probing Perturbation of Bovine Lung Surfactant Extracts by Albumin using DSC and 2H-NMR

    PubMed Central

    Nag, Kaushik; Keough, Kevin M. W.; Morrow, Michael R.

    2006-01-01

    Lung surfactant (LS), a lipid-protein mixture, forms films at the lung air-water interface and prevents alveolar collapse at end expiration. In lung disease and injury, the surface activity of LS is inhibited by leakage of serum proteins such as albumin into the alveolar hypophase. Multilamellar vesicular dispersions of a clinically used replacement, bovine lipid extract surfactant (BLES), to which (2% by weight) chain-perdeuterated dipalmitoylphosphatidycholine (DPPG mixtures-d62) had been added, were studied using deuterium-NMR spectroscopy (2H-NMR) and differential scanning calorimetry (DSC). DSC scans of BLES showed a broad gel to liquid-crystalline phase transition between 10–35°C, with a temperature of maximum heat flow (Tmax) around 27°C. Incorporation of the DPPC-d62 into BLES-reconstituted vesicles did not alter the Tmax or the transition range as observed by DSC or the hydrocarbon stretching modes of the lipids observed using infrared spectroscopy. Transition enthalpy change and 2H-NMR order parameter profiles were not significantly altered by addition of calcium and cholesterol to BLES. 2H-NMR spectra of the DPPC-d62 probes in these samples were characteristic of a single average lipid environment at all temperatures. This suggested either continuous ordering of the bilayer through the transition during cooling or averaging of the DPPC-d62 environment by rapid diffusion between small domains on a short timescale relative to that characteristic of the 2H-NMR experiment. Addition of 10% by weight of soluble bovine serum albumin (1:0.1, BLES/albumin, dry wt/wt) broadened the transition slightly and resulted in the superposition of 2H-NMR spectral features characteristic of coexisting fluid and ordered phases. This suggests the persistence of phase-separated domains throughout the transition regime (5–35°C) of BLES with albumin. The study suggests albumin can cause segregation of protein bound-lipid domains in surfactant at NMR timescales (10−5 s

  16. On the Use of DSC-MRI for Measuring Vascular Permeability

    PubMed Central

    Skinner, Jack T; Moots, Paul L; Ayers, Gregory D; Quarles, C. Chad

    2015-01-01

    Background and Purpose Contrast agent (CA) extravasation has been shown to confound brain tumor perfusion measurements using DSC-MRI, necessitating the use of correction techniques (e.g. Weisskoff, Bjornerud). Model parameters (K2 and Ka) postulated to reflect vessel permeability can be extracted from these correction methods, however the biophysical interpretation of these parameters and their relationship to commonly used MR measures of vascular permeability (e.g. Ktrans) remains unclear. Given that vascular density, as assessed by blood volume, and vascular permeability, as reflected by Ktrans (and potentially K2 or Ka), report on unique and clinically informative vascular characteristics, there is a compelling interest to simultaneously assess these features. Materials and Methods Multi-echo DSC-MRI data was acquired, allowing the simultaneous computation and voxel-wise comparison of single- and dual-echo derived measures of K2, Ka and Ktrans in glioma patients. This acquisition enabled the investigation of competing T1 and T2* leakage effects and echo time dependency on these parameters. Results K2 and Ka displayed non-significant (p = 0.150 and p = 0.060, respectively) voxel-wise linear correlations with Ktrans, while a significant (p < 0.0001) inverse relationship was observed between K2 and Ka [r2 = 0.466–0.984]. Significantly different (p < 0.005) mean estimates were found between voxels exhibiting predominately T1 or T2* leakage effects for K2 and Ka. Ktrans, however, was observed to be similar between these voxels (0.109 min−1 vs 0.092 min−1). Significant differences (p < 0.0005) in ve (0.285 vs 0.167) were also observed between cohorts. Additionally, K2 and Ka were found to have a significant quadratic relationship (p = 0.031 and p = 0.005, respectively) with ve. Conclusion Estimates of vascular permeability in brain tumors may be simultaneously acquired from multiple-echo DSC-MRI via Ktrans, however caution should be used in assuming a similar

  17. Thermooxidative stability of poppy seeds studied by non-isothermal DSC measurements.

    PubMed

    Cibulková, Zuzana; Čertík, Milan; Dubaj, Tibor

    2014-05-01

    Papaver somniferum L. is an important crop cultivated mostly for seed production. Poppy seeds have a high nutritive value and are used as a food and as a source of edible oil. This oil is a rich source of polyunsaturated fatty acids. It is well known that the unsaturated fatty acids easily undergo oxidation reactions, which lead to the reduction of shelf life, nutritional quality, development of unpleasant tastes and odors. The goal of this study was to develop the methodology for testing the stability of poppy seeds using non-isothermal DSC. For the treatment of the experimental data a method based on non-Arrhenian temperature function has been applied and the values the kinetic parameters have been obtained. In order to assess the durability of the commercial poppy seeds, the lengths of induction periods have been calculated. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. DSC and curing kinetics study of epoxy grouting diluted with furfural -acetone slurry

    NASA Astrophysics Data System (ADS)

    Yin, H.; Sun, D. W.; Li, B.; Liu, Y. T.; Ran, Q. P.; Liu, J. P.

    2016-07-01

    The use of furfural-acetone slurry as active diluents of Bisphenol-A epoxy resin (DGEBA) groutings has been studied by dynamic and non-isothermal DSC for the first time. Curing kinetics study was investigated by non-isothermal differential scanning calorimetries at different heating rates. Activation enery (Ea) was calculated based on Kissinger and Ozawa Methods, and the results showed that Ea increased from 58.87 to 71.13KJ/mol after the diluents were added. The furfural-acetone epoxy matrix could cure completely at the theoretical curing temperature of 365.8K and the curing time of 139mins, which were determined by the kinetic model parameters.

  19. DSC and Raman spectra of α and β-Endosulfan plus 60/40 mixture

    NASA Astrophysics Data System (ADS)

    Schmidt, Walter F.; Nguyen, Julie K.; Qin, Jianwei; Kim, Moon S.; Mookherji, Swati; McConnell, Laura L.; Hapeman, Cathleen J.

    2013-05-01

    The symmetrical β-conformer of endosulfan has the identical chemical composition of the asymmetrical α-conformer, and both have very different melting/boiling points. The α- and β-isomer however have markedly different Raman spectra at each of 50°C, 75°C and 100°C. Moreover, the commercially available Raman spectra of the 60/40 (α-/β-) mixture at the same temperatures is discrete from either a- and b-isomer alone. Previous research demonstrated that at a- boiling point 110°C, β-conformer partially converts to α-. DSC curves of mixtures suggest thermal interactions and conformational changes occurs in BOTH α- and β-isomer at temperatures even 60°C lower than the liquid/gas phase transition.

  20. The life and times of John Beard, DSc (1858-1924).

    PubMed

    Moss, Ralph W

    2008-12-01

    The British developmental biologist John Beard, DSc (1858-1924) is little remembered today. Yet, he made outstanding contributions to the life sciences. Beard deserves to be included among the leading biologists of the late 19th and early 20th century. He has been hailed as a forerunner of the present-day theory of the cancer stem cell (CSC). He was the first to point to the parallels between cancer and the trophoblastic cells that envelop and nourish the embryo, characterizing cancer as "irresponsible trophoblast." He pointed out that the initiation of fetal pancreatic function coincided with a reduction in the invasiveness of trophoblast, which otherwise might progress to clinical cancer (ie, choriocarcinoma). Based on the above propositions, he recommended the therapeutic use of pancreatic enzymes in treating cancer and other diseases. This therapy created a worldwide controversy, and although rejected in his day, persists in the world of complementary and alternative medicine (CAM) today.

  1. Phase-Change Characteristic Analysis of Partially Melted Sodium Acetate Trihydrate Using DSC

    NASA Astrophysics Data System (ADS)

    Jin, Xing; Medina, Mario A.; Zhang, Xiaosong; Zhang, Shuanglong

    2014-01-01

    Sodium acetate trihydrate (SAT), which is a kind of phase-change material, offers high potential for application in thermal energy storage. However, SAT has a natural tendency to supercool during its solidification process. Adding nucleating agents has been suggested as a possible solution. In this paper, the phase-change characteristics of the partially melted SAT were analyzed using a differential scanning calorimeter (DSC). A phenomenon related to SAT undergoing phase change was discovered and analyzed. The results showed that if SAT were cooled when it was partially melted, it would release heat and quickly solidify without adding any nucleating agents. Therefore, if the temperature range of SAT was controlled properly, supercooling could be significantly prevented.

  2. In situ stability of substrate-associated cellulases studied by DSC.

    PubMed

    Alasepp, Kadri; Borch, Kim; Cruys-Bagger, Nicolaj; Badino, Silke; Jensen, Kenneth; Sørensen, Trine H; Windahl, Michael S; Westh, Peter

    2014-06-24

    This work shows that differential scanning calorimetry (DSC) can be used to monitor the stability of substrate-adsorbed cellulases during long-term hydrolysis of insoluble cellulose. Thermal transitions of adsorbed enzyme were measured regularly in subsets of a progressing hydrolysis, and the size of the transition peak was used as a gauge of the population of native enzyme. Analogous measurements were made for enzymes in pure buffer. Investigations of two cellobiohydrolases, Cel6A and Cel7A, from Trichoderma reesei, which is an anamorph of the fungus Hypocrea jerorina, showed that these enzymes were essentially stable at 25 °C. Thus, over a 53 h experiment, Cel6A lost less than 15% of the native population and Cel7A showed no detectable loss for either the free or substrate-adsorbed state. At higher temperatures we found significant losses in the native populations, and at the highest tested temperature (49 °C) about 80% Cel6A and 35% of Cel7A was lost after 53 h of hydrolysis. The data consistently showed that Cel7A was more long-term stable than Cel6A and that substrate-associated enzyme was less long-term stable than enzyme in pure buffer stored under otherwise equal conditions. There was no correlation between the intrinsic stability, specified by the transition temperature in the DSC, and the long-term stability derived from the peak area. The results are discussed with respect to the role of enzyme denaturation for the ubiquitous slowdown observed in the enzymatic hydrolysis of cellulose.

  3. Does thermodynamic stability of peritoneal collagen change during laparoscopic cholecystectomies? A differential scanning calorimetry (DSC) study.

    PubMed

    Torres, Kamil; Trębacz, Hanna; Bącik-Donica, Magdalena; Atras, Agnieszka; Torres, Anna; Plewa, Zbigniew

    2014-09-01

    Carbon dioxide pneumoperitoneum used during laparoscopic surgeries alters the integrity of the peritoneum and results in denudation of the basal lamina that might cause altered immune response, inhibited fibrinolysis, hypoxia, and acidosis. The changes in the structure of pneumoperitoneum were described as bulging of mesothelial cells, irregular cell junction's cell membrane degradation, and mesodermal edema. As denaturation of peritoneal proteins reflects overall condition of its structure and interactions with the surrounding molecules, the physical status of collagen was assessed on the basis of parameters of thermal denaturation measured by DSC method. Twenty-four female patients operated on due to cholelithiasis were enrolled in this study. Laparoscopic cholecystectomy was performed using standard four-trocar technique, and standard values of insufflated carbon dioxide pneumoperitoneum were used. After trocar placement, the first collection of peritoneal sample (sample A) was performed. The second peritoneal sample (sample B) was collected after the removal of gall bladder. Differential scanning calorimetry (Q200 calorimeter, TA Instruments) was performed on samples defrosted at room temperature. In all samples of peritoneum, a nonreversible endothermal process recognized as denaturation was observed. Sample B obtained at the end of surgery did not differ from sample A obtained at the beginning in terms of all parameters under study. Temperature of denaturation in A and B was correlated only marginally, but enthalpy and specific heat were significantly correlated. The analysis of data from DSC measurements did not reveal differences in physical stability of collagen in peritoneal samples obtained at the beginning and at the end of surgery. Significant negative correlations between duration of CO2 pneumoperitoneum and enthalpy of denaturation in sample B were found. Differences in enthalpy of denaturation may reflect a quantitative relation between amount of

  4. Comparison of dual-echo DSC-MRI- and DCE-MRI-derived contrast agent kinetic parameters.

    PubMed

    Quarles, C Chad; Gore, John C; Xu, Lei; Yankeelov, Thomas E

    2012-09-01

    The application of dynamic susceptibility contrast (DSC) MRI methods to assess brain tumors is often confounded by the extravasation of contrast agent (CA). Disruption of the blood-brain barrier allows CA to leak out of the vasculature leading to additional T(1), T(2) and T(2) relaxation effects in the extravascular space, thereby affecting the signal intensity time course in a complex manner. The goal of this study was to validate a dual-echo DSC-MRI approach that separates and quantifies the T(1) and T(2) contributions to the acquired signal and enables the estimation of the volume transfer constant, K(trans), and the volume fraction of the extravascular extracellular space, v(e). To test the validity of this approach, DSC-MRI- and dynamic contrast enhanced (DCE) MRI-derived K(trans) and v(e) estimates were spatially compared in both 9L and C6 rat brain tumor models. A high degree of correlation (concordance correlation coefficients >0.83, Pearson's r>0.84) and agreement was found between the DSC-MRI- and DCE-MRI-derived measurements. These results indicate that dual-echo DSC-MRI can be used to simultaneously extract reliable DCE-MRI kinetic parameters in brain tumors in addition to conventional blood volume and blood flow metrics.

  5. Laser-high-speed-DSC: Process-oriented Thermal Analysis of PA 12 in Selective Laser Sintering

    NASA Astrophysics Data System (ADS)

    Lanzl, Lydia; Wudy, Katrin; Drexler, Maximilian; Drummer, Dietmar

    In the Selective Laser Sintering process very high heating rates occur due to the melting of the material by a laser. Extreme scanning rates could not be measured by conventional thermal analysis methods, since typical heating rates for DSC (differential scanning calorimetry) are between 5-20K min-1. By using a Laser-High-Speed-DSC, a self-developed combination of a Flash-DSC and a fitted laser head, the sample is directly heated by a CO2 laser like in the SLS process. These experiments allow a process-oriented thermal analyzation of the material. In this paper, the set-up and function of this new measuring method is introduced. Furthermore, the reliability of the measurements is evaluated by statistical design of experiment methods. By using this new measuring method, the time-dependent melting behavior of the polymer can be analyzed. Moreover, sample temperatures and heating rates dependent on laser exposure times can be quantified.

  6. Localization and interaction of hydroxyflavones with lipid bilayer model membranes: a study using DSC and multinuclear NMR.

    PubMed

    Sinha, Ragini; Joshi, Akshada; Joshi, Urmila J; Srivastava, Sudha; Govil, Girjesh

    2014-06-10

    The localization and interaction of six naturally occurring flavones (FLV, 5HF, 6HF, 7HF, CHY and BLN) in DPPC bilayers were studied using DSC and multi-nuclear NMR. DSC results indicate that FLV and 6HF interact with alkyl chains. The (1)H NMR shows interaction of flavones with the sn-glycero region. Ring current induced chemical shifts indicate that 6HF and BLN acquire parallel orientation in bilayers. 2D NOESY spectra indicate partitioning of the B-ring into the alkyl chain region. The DSC, NMR and binding studies indicate that 5HF and 7HF are located near head group region, while 6HF, CHY and BLN are located in the vicinity of sn-glycero region, and FLV is inserted deepest in the membrane.

  7. An Investigation of Thermal Characteristic of Mechanical Crimp Textured Polyester Yarn by Differential Scanning Calorimeter (DSC)

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Someshwar S.; Shaikh, Tasnim N.; Pratap, Arun

    2010-06-01

    Deficiencies related to the lack of bulk in flat continuous filament yarns make them unsuitable for apparel, home textiles as well as other applications such as car seat covering. Hence, texturising is employed to impart lofty and bulky characteristics to them. The two major texturising techniques employed for polyester yarn are false-twist and air-jet texturising. Out of these earlier technique depends on the thermoplasticity of the yarn being textured whereas the later one demands subsequent amount of compressed air to carry out cold fluid texturising. A new concept of mechanical crimp texturising has been designed to overcome these limitations of commercially successful techniques. In this new technique, pre-twisted FDY (Fully Drawn Yarn) flat multifilament yarn has been subjected to the higher false-twisting (depending on yarn fineness) action under the condition of underfeed (depending on ductility of parent yarn). The torque caused due to high level of false-twisting, forces the filaments to follow helical path at a certain angle (depends on magnitude of twist and denier per filament) to the filament yarn longitudinal axis. Internal stresses arising in single filaments tend to bend the filament and take the shape of spatial helical spring. After the yarn has passed through the false twisting unit, the initial twist would reassert itself and lock the already formed crimpy convolutions in position. Mechanical crimp textured polyester yarns with different pre-twist and false-twist levels have been subjected to thermal stress analysis using differential Scanning Calorimeter (DSC) in heat-cool-heat mode. The samples were heated at a rate of 10°C/minute. Almost all samples appear to be crystalline in nature. However, the melting endotherm does not show sharp peak. Instead, the diffuse nature of the peak is a signature of a partial crystalline nature (48%) of the samples. After melting the specimens, cooling of the same leads to crystallization of the material

  8. Simultaneous TG/DSC (thermogravimetry/differential scanning calorimetry) and TG/MS (thermogravimetry/mass spectrometry) analyses of polymeric and energetic materials

    SciTech Connect

    Whitaker, R B; Brown, C R; Chang, C; McDaniel, J A; Shell, T L

    1987-01-01

    The utility of simultaneous thermal analysis techniques, such as TG/DSC and TG/MS, has been demonstrated for both energetic and polymeric materials. TG/DSC can assist in elucidating reaction mechanisms and determining weight losses for endothermic transitions which precede decomposition of energetic materials. The endothermic and exothermic nature of decomposition processes can be defined by TG/DSC and the decomposition products identified by TG/MS.

  9. Preparation and Microstructural Characterization of Griseofulvin Microemulsions Using Different Experimental Methods: SAXS and DSC

    PubMed Central

    Moghimipour, Eskandar; Salimi, Anayatollah; Changizi, Sahar

    2017-01-01

    Purpose: The objective of the present study is to formulate and evaluate a new microemulsion (ME) for topical delivery of griseofulvin. Methods: The solubilities of griseofulvin in different combinations of surfactant to co-surfactant (S/Co ratio) were determined. Accordingly, based on their phase diagrams, eight microemulsions were formulated and then evaluated with respect to their particle size, surface tension, viscosity, conductivity, zeta potential and stability. Their release behavior, Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), refractory index (RI), pH and Small-angle-X-ray scattering (SAXS) were also assessed. Results: The results indicated that the mean droplet size of the MEs ranged from 30.9 to 84.3 nm. Their zeta potential varied from -4.5 to -20.8. Other determined characteristics were viscosity: 254-381 cps, pH: 5.34-6.57, surface tension: 41.16- 42.83 dyne.cm-1, conductivity: 0.0442 – 0.111 ms.cm-1. The drug release was in the range of 22.4 to 43.69 percent. Also, hexagonal, cubic and lamellar liquid crystals were observed in SAXS experiments. Conclusion: It can be concluded that any alteration in MEs constituents directly affects their microstructure, shape, droplet size and their other physicochemical properties. PMID:28761831

  10. Complex Heat Capacity of Lithium Borate Glasses Studied by Modulated DSC

    SciTech Connect

    Matsuda, Yu; Ike, Yuji; Matsui, Chihiro; Kodama, Masao; Kojima, Seiji

    2006-05-05

    Complex heat capacity, C{sub p}* = C{sub p}' - iC{sub p}'', of lithium borate glasses Li2O{center_dot}(1-x)B2O3 (x = 0.00 - 0.33) has been investigated by Modulated DSC (MDSC). We have successfully observed the frequency dependent C{sub p}* by MDSC in the frequency range 0.01 to 0.1 Hz, and the average relaxation time of glass transition has been determined as a function of temperature. Moreover, the composition dependence of the thermal properties has been investigated. The calorimetric glass transition temperatures become higher with the increase of concentration of Li2O and show the board maximum around x = 0.26-0.28. The width of glass transition region becomes narrower as Li2O increases. These results relate to the change of the fragility of the system. It has been proven that the complex heat capacity spectroscopy by MDSC is a powerful tool to investigate the glass transition phenomena.

  11. Transgenic mice overexpressing desmocollin-2 (DSC2) develop cardiomyopathy associated with myocardial inflammation and fibrotic remodeling

    PubMed Central

    Garnett, Lauren; Martens, Kristina; Abdelfatah, Nelly; Rodriguez, Marcela; Diao, Catherine; Chen, Yong-Xiang; Gordon, Paul M. K.; Nygren, Anders; Gerull, Brenda

    2017-01-01

    Background Arrhythmogenic cardiomyopathy is an inherited heart muscle disorder leading to ventricular arrhythmias and heart failure, mainly as a result of mutations in cardiac desmosomal genes. Desmosomes are cell-cell junctions mediating adhesion of cardiomyocytes; however, the molecular and cellular mechanisms underlying the disease remain widely unknown. Desmocollin-2 is a desmosomal cadherin serving as an anchor molecule required to reconstitute homeostatic intercellular adhesion with desmoglein-2. Cardiac specific lack of desmoglein-2 leads to severe cardiomyopathy, whereas overexpression does not. In contrast, the corresponding data for desmocollin-2 are incomplete, in particular from the view of protein overexpression. Therefore, we developed a mouse model overexpressing desmocollin-2 to determine its potential contribution to cardiomyopathy and intercellular adhesion pathology. Methods and results We generated transgenic mice overexpressing DSC2 in cardiac myocytes. Transgenic mice developed a severe cardiac dysfunction over 5 to 13 weeks as indicated by 2D-echocardiography measurements. Corresponding histology and immunohistochemistry demonstrated fibrosis, necrosis and calcification which were mainly localized in patches near the epi- and endocardium of both ventricles. Expressions of endogenous desmosomal proteins were markedly reduced in fibrotic areas but appear to be unchanged in non-fibrotic areas. Furthermore, gene expression data indicate an early up-regulation of inflammatory and fibrotic remodeling pathways between 2 to 3.5 weeks of age. Conclusion Cardiac specific overexpression of desmocollin-2 induces necrosis, acute inflammation and patchy cardiac fibrotic remodeling leading to fulminant biventricular cardiomyopathy. PMID:28339476

  12. Thermodynamic optimization of individual steel database by means of systematic DSC measurements according the CALPHAD approach

    NASA Astrophysics Data System (ADS)

    Presoly, P.; Six, J.; Bernhard, C.

    2016-03-01

    Reliable thermodynamic data are essential information required for the design of new steel types and are a prerequisite to effective process optimization and simulation. Moreover, it is important to know the exact temperatures at which the high-temperature phase transformations (TLiquid, TSolid, TPerit, Tγ→δ) occur in order to describe the solidification sequence and to describe further processing parameters. By utilizing DTA/DSC measurements, our earlier experimental studies of selected commercial DP, TRIP and high-Mn TWIP steels, have indicated that currently commercially available databases can often not be utilised to reliably describe the behaviour and microstructural development in such complex alloy systems. Because of these ostensible deficiencies, an experimental study was undertaken in an attempt to determine the pertaining thermodynamic data to analyse the behaviour of the important five- component Fe-C-Si-Mn-Al alloy system. High purity model alloys with systematic alloy variations were prepared and utilized in order to determine the influence of individual alloying elements in this complex, but industrially important alloy system. The present study provides new validated experimental thermodynamic data and analysis of the five-component Fe-C-Si- Mn-Al system, which will allow the construction of new phase diagrams, prediction of solidification sequences and the assessment of micro-segregation.

  13. Thermal characterization and model free kinetics of aged epoxies and foams using TGA and DSC methods.

    SciTech Connect

    Cordaro, Joseph Gabriel; Kruizenga, Alan Michael; Nissen, April

    2013-10-01

    Two classes of materials, poly(methylene diphenyl diisocyanate) or PMDI foam, and cross-linked epoxy resins, were characterized using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), to help understand the effects of aging and %E2%80%9Cbake-out%E2%80%9D. The materials were evaluated for mass loss and the onset of decomposition. In some experiments, volatile materials released during heating were analyzed via mass spectroscopy. In all, over twenty materials were evaluated to compare the mass loss and onset temperature for decomposition. Model free kinetic (MFK) measurements, acquired using variable heating rate TGA experiments, were used to calculate the apparent activation energy of thermal decomposition. From these compiled data the effects of aging, bake-out, and sample history on the thermal stability of materials were compared. No significant differences between aged and unaged materials were detected. Bake-out did slightly affect the onset temperature of decomposition but only at the highest bake-out temperatures. Finally, some recommendations for future handling are made.

  14. DSC study of the isothermal crystallization of iPP-CNF nanocomposites

    NASA Astrophysics Data System (ADS)

    Chipara, Dorina M.; Chipara, Mircea

    2013-03-01

    Nanocomposite materials have been obtained by dispersing vapor grown carbon nanofibers (VGCNFs) with diameters ranging between 60 and 100 nm and lengths between 30,000 and 100,000 nm supplied by Pyrograf Products, Inc (PR-24AG) within a polymer matrix - isotactic polypropylene (iPP) - type Marlex HLN-120-01 with density 0.906 g/cm3 and melt flow rate at 230 oC of 12 g/10 min, supplied by Philips Sumika Polypropylene Company. VGCNFs have been purified and disentangled by reflux in dichloromethane and deionized water followed by vacuum filtering (for 24 h) and drying at 110 oC for 24h. The nanocomposites were obtained by melt mixing at 180 oC for 9 minutes with a speed of 65 rpm followed by an additional mixing at 90 rpm for 5 minutes, using a HAAKE Rheomix, Nanocomposites loaded with various amounts of VGCNFs (0%, 1%, 2.5%, 5%, 7.5%, 10%, 15%, and 20% wt.) have been prepared and investigated by TA DSC Q-500. Isothermal crystallization was investigated in detail and analyzed by using an expression derived from the Avrami equation. The effect of the filler on the isothermal crystallization of iPP is discussed in detail. The research is focused on the effect of VGCNF on the degree of crystallization of iPP, crystallization rate, and dimensionality of the crystallization process. This research has been supported by National Science Foundation under DMR. Contract grant number 0934157.

  15. TG/DSC-FTIR and Py-GC investigation on pyrolysis characteristics of petrochemical wastewater sludge.

    PubMed

    Chen, Jianbiao; Mu, Lin; Jiang, Bo; Yin, Hongchao; Song, Xigeng; Li, Aimin

    2015-09-01

    The pyrolysis characteristics of petrochemical wastewater sludge (PS) were evaluated using TG/DSC-FTIR and fixed-bed reactor with GC. TGA experiments indicated that the pyrolysis of PS proceeded in three phases, and the thermographs shifted to higher temperatures with increasing heating rate. Chars FTIR showed that the absorption of O-H, C-H, C=O and C-C decreased with pyrolysis temperatures increasing. Gases FTIR correspondingly showed that H2O, CO, and CH4 generated at higher temperatures. For the fixed-bed reactor tests, H2 and CO were relatively higher in the pyrolysis gases, and CH4 was negligible at 436K. The kinetic triplets of PS pyrolysis were estimated by Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and integral master-plots method. The results suggested that the most potential kinetic models for the first and second phase were the order reaction model, while the random nucleation and nuclei growth model for the third phase.

  16. Raman, DSC, ESR and optical properties of lithium cadmium zinc tellurite glasses

    NASA Astrophysics Data System (ADS)

    Sreenivasulu, V.; Upender, G.; Swapna; Priya, V. Vamsi; Mouli, V. Chandra; Prasad, M.

    2014-12-01

    The glasses with composition 64TeO2-15ZnO-(20-x)CdO-xLi2O-1V2O5 (0≤x≤20 mol%) were prepared by conventional melt quenching technique. X-ray diffraction was used to confirm the amorphous nature. The optical absorption studies revealed that the cut-off wavelength decreases while optical energy gap (Eopt) and Urbach energy (ΔE) values increase with an increase of Li2O. Refractive index (n) evaluated from Eopt was found to decrease with increase of Li2O content. The physical parameters such as density (ρ), molar volume (Vm) and oxygen packing density (OPD) have been analyzed and discussed. The electron paramagnetic resonance (EPR) spectra of VO2+ glasses have been recorded on X-band (v=9.14 GHz) at room temperature. The spin Hamiltonian parameters of VO2+ ions have been calculated. It has been found that V4+ ions in these glasses exist as VO2+ in octahedral coordination with a tetragonal distortion. Raman spectroscopic studies showed that the glass network consists of TeO4, TeO3+1/TeO3 and ZnO4 units as basic structural units. The glass transition temperature (Tg), onset crystallization (To) and thermal stability (ΔT) were determined from Differential Scanning Calorimetry (DSC).

  17. Reliable estimation of capillary transit time distributions using DSC-MRI

    PubMed Central

    Mouridsen, Kim; Hansen, Mikkel Bo; Østergaard, Leif; Jespersen, Sune Nørhøj

    2014-01-01

    The regional availability of oxygen in brain tissue is traditionally inferred from the magnitude of cerebral blood flow (CBF) and the concentration of oxygen in arterial blood. Measurements of CBF are therefore widely used in the localization of neuronal response to stimulation and in the evaluation of patients suspected of acute ischemic stroke or flow-limiting carotid stenosis. It was recently demonstrated that capillary transit time heterogeneity (CTH) limits maximum oxygen extraction fraction (OEFmax) that can be achieved for a given CBF. Here we present a statistical approach for determining CTH, mean transit time (MTT), and CBF using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI). Using numerical simulations, we demonstrate that CTH, MTT, and OEFmax can be estimated with low bias and variance across a wide range of microvascular flow patterns, even at modest signal-to-noise ratios. Mean transit time estimated by singular value decomposition (SVD) deconvolution, however, is confounded by CTH. The proposed technique readily identifies malperfused tissue in acute stroke patients and appears to highlight information not detected by the standard SVD technique. We speculate that this technique permits the non-invasive detection of tissue with impaired oxygen delivery in neurologic disorders such as acute ischemic stroke and Alzheimer's disease during routine diagnostic imaging. PMID:24938401

  18. Some considerations on the vibrational environment of the DSC-DCMIX1 experiment onboard ISS

    NASA Astrophysics Data System (ADS)

    Jurado, R.; Gavaldà, Jna.; Simón, M. J.; Pallarés, J.; Laverón-Simavilla, A.; Ruiz, X.; Shevtsova, V.

    2016-12-01

    The present work attempts to characterize the accelerometric environment of the DSC-DCMIX1 thermodiffusion experiment carried out in the International Space Station, from November 7th 2011 until January 16th 2012. Quasi-steady and vibrational/transient data coming from MAMS and SAMS2 sensors have been downloaded from the database of the PIMS NASA website. To be as exhaustive as possible, simultaneous digital signals coming from different SAMS2 sensors located in the Destiny and Columbus modules have also been considered. In order to detect orbital adjustments, dockings, undockings, as well as, quiescent periods, when the experiment runs were active, we have used the quasi-steady eight hours averaged (XA, YA and ZA) acceleration functions as well as the eight hours RMS ones. To determine the spectral contents of the different signals the Thomson multitaper and Welch methods have been used. On the other hand, to suppress the high levels of noise always existing in the raw SAMS2 signals, denoising techniques have been preferred for comparative reboostings considerations. Finally, the RMS values for specific 1/3 octave frequency bands showed that the International Space Station vibratory limit requirements have not been totally accomplished during both quiescent periods and strong disturbances, specially in the low frequency range.

  19. Perfusion deconvolution in DSC-MRI with dispersion-compliant bases.

    PubMed

    Pizzolato, Marco; Boutelier, Timothé; Deriche, Rachid

    2017-02-01

    Perfusion imaging of the brain via Dynamic Susceptibility Contrast MRI (DSC-MRI) allows tissue perfusion characterization by recovering the tissue impulse response function and scalar parameters such as the cerebral blood flow (CBF), blood volume (CBV), and mean transit time (MTT). However, the presence of bolus dispersion causes the data to reflect macrovascular properties, in addition to tissue perfusion. In this case, when performing deconvolution of the measured arterial and tissue concentration time-curves it is only possible to recover the effective, i.e. dispersed, response function and parameters. We introduce Dispersion-Compliant Bases (DCB) to represent the response function in the presence and absence of dispersion. We perform in silico and in vivo experiments, and show that DCB deconvolution outperforms oSVD and the state-of-the-art CPI+VTF techniques in the estimation of effective perfusion parameters, regardless of the presence and amount of dispersion. We also show that DCB deconvolution can be used as a pre-processing step to improve the estimation of dispersion-free parameters computed with CPI+VTF, which employs a model of the vascular transport function to characterize dispersion. Indeed, in silico results show a reduction of relative errors up to 50% for dispersion-free CBF and MTT. Moreover, the DCB method recovers effective response functions that comply with healthy and pathological scenarios, and offers the advantage of making no assumptions about the presence, amount, and nature of dispersion. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Anisotropic-isotropic transition of solutions of cellulose derivatives: a DSC study. [Differential scanning calorimetry

    SciTech Connect

    Navard, P.; Haudin, J.M.; Dayan, S.; Sixou, P.

    1983-01-01

    Cellulose acetate (CA)/trifluoroacetic acid (TFA), cellulose triacetate (CTA)/trifluoroacetic acid, and hydroxypropylcellulose (HPC)/water solutions are able to develop liquid crystalline (cholesteric) order above a certain polymer concentration C/sup **/. When the polymer concentration C is smaller than C/sup **/, no peak is recorded on a DSC trace upon heating. When C>C/sup **/, a well-defined peak for CA/TFA appears at a temperature T/sub t/. This peak is attributed to the anisotropic-isotropic phase transition. The origin and nature of this peak are discussed in the light of available theories. A T/sub t/-C phase diagram is plotted. For CTA/TFA solutions, one or two peaks arise, depending onpolymer concentration. The peak at the higher temperature is attributed to the anisotropic-isotropic transition, and the peak at the lower temperature to the destruction of a ''gel-like'' phase. HPC/water solutions have a very different behavior. Upon heating, they are transformed into a turbid phase regardless of the concentration. 22 references, 11 figures, 1 table.

  1. FTIR, XRD and DSC studies of nanochitosan, cellulose acetate and polyethylene glycol blend ultrafiltration membranes.

    PubMed

    Vinodhini, P Angelin; K, Sangeetha; Thandapani, Gomathi; P N, Sudha; Jayachandran, Venkatesan; Sukumaran, Anil

    2017-03-29

    In the present work, a series of novel nanochitosan/cellulose acetate/polyethylene glycol (NCS/CA/PEG) blend flat sheet membranes were fabricated in different ratios (1:1:1, 1:1:2, 2:1:1, 2:1:2, 1:2:1, 2:2:1) in a polar solvent of N,N'-dimethylformamide (DMF) using the most popular phase inversion method. Nanochitosan was prepared by the ionotropic gelation method and its average particle size has been analyzed using Dynamic Light Scattering (DLS) method. The effect of blending of the three polymers was investigated using FTIR and XRD studies. FTIR results confirmed the formation of well-blended membranes and the XRD analysis revealed enhanced amorphous nature of the membrane ratio 2:1:2. DSC study was conducted to find out the thermal behavior of the blend membranes and the results clearly indicated good thermal stability and single glass transition temperature (Tg) of all the prepared membranes. Asymmetric nature and rough surface morphology was confirmed using SEM analysis. From the results it was evident that the blending of the polymers with higher concentration of nanochitosan can alter the nature of the resulting membranes to a greater extent and thus amorphous membranes were obtained with good miscibility and compatibility.

  2. DSC studies of retrogradation and amylose lipid complex transition taking place in gamma irradiated wheat starch

    NASA Astrophysics Data System (ADS)

    Cieśla, K.; Eliasson, A. C.

    2007-12-01

    The effect of gamma irradiation ( 60Co) with doses of 5-30 kGy on the amylose-lipid complex transition and retrogradation occurring in gels containing ca. 50% and ca. 20% wheat starch was studied by differential scanning calorimetry (DSC) during heating-cooling-heating cycles (up to three cycles). Transition of the amylose-lipid complex occurs in all the irradiated samples at a lower temperature as compared to the non-irradiated starch. That effect was larger when the radiation dose was higher. A further thermal treatment causes a decrease of the transition temperature in the irradiated samples, with no effect or increase of that temperature observed for the non-irradiated ones. Irradiation hinders retrogradation taking place in 50% gels but facilitates the process occurring in 20% gels. The differences between the irradiated and the non-irradiated samples are more evident in the every next heating or cooling cycle as well as after storage and in the case of ca. 50% suspensions as compared to ca. 20% suspensions. The results point out to the deterioration of the structure of the complexes formed in the irradiated starch as compared to the non-irradiated one.

  3. Development and validation of an open source quantification tool for DSC-MRI studies.

    PubMed

    Gordaliza, P M; Mateos-Pérez, J M; Montesinos, P; Guzmán-de-Villoria, J A; Desco, M; Vaquero, J J

    2015-03-01

    This work presents the development of an open source tool for the quantification of dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion studies. The development of this tool is motivated by the lack of open source tools implemented on open platforms to allow external developers to implement their own quantification methods easily and without the need of paying for a development license. This quantification tool was developed as a plugin for the ImageJ image analysis platform using the Java programming language. A modular approach was used in the implementation of the components, in such a way that the addition of new methods can be done without breaking any of the existing functionalities. For the validation process, images from seven patients with brain tumors were acquired and quantified with the presented tool and with a widely used clinical software package. The resulting perfusion parameters were then compared. Perfusion parameters and the corresponding parametric images were obtained. When no gamma-fitting is used, an excellent agreement with the tool used as a gold-standard was obtained (R(2)>0.8 and values are within 95% CI limits in Bland-Altman plots). An open source tool that performs quantification of perfusion studies using magnetic resonance imaging has been developed and validated using a clinical software package. It works as an ImageJ plugin and the source code has been published with an open source license. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Kinetics of Thermal Decomposition of Ammonium Perchlorate by TG/DSC-MS-FTIR

    NASA Astrophysics Data System (ADS)

    Zhu, Yan-Li; Huang, Hao; Ren, Hui; Jiao, Qing-Jie

    2014-01-01

    The method of thermogravimetry/differential scanning calorimetry-mass spectrometry-Fourier transform infrared (TG/DSC-MS-FTIR) simultaneous analysis has been used to study thermal decomposition of ammonium perchlorate (AP). The processing of nonisothermal data at various heating rates was performed using NETZSCH Thermokinetics. The MS-FTIR spectra showed that N2O and NO2 were the main gaseous products of the thermal decomposition of AP, and there was a competition between the formation reaction of N2O and that of NO2 during the process with an iso-concentration point of N2O and NO2. The dependence of the activation energy calculated by Friedman's iso-conversional method on the degree of conversion indicated that the AP decomposition process can be divided into three stages, which are autocatalytic, low-temperature diffusion and high-temperature, stable-phase reaction. The corresponding kinetic parameters were determined by multivariate nonlinear regression and the mechanism of the AP decomposition process was proposed.

  5. Cerebral perfusion alterations in epileptic patients during peri-ictal and post-ictal phase: PASL vs DSC-MRI.

    PubMed

    Pizzini, Francesca B; Farace, Paolo; Manganotti, Paolo; Zoccatelli, Giada; Bongiovanni, Luigi G; Golay, Xavier; Beltramello, Alberto; Osculati, Antonio; Bertini, Giuseppe; Fabene, Paolo F

    2013-07-01

    Non-invasive pulsed arterial spin labeling (PASL) MRI is a method to study brain perfusion that does not require the administration of a contrast agent, which makes it a valuable diagnostic tool as it reduces cost and side effects. The purpose of the present study was to establish the viability of PASL as an alternative to dynamic susceptibility contrast (DSC-MRI) and other perfusion imaging methods in characterizing changes in perfusion patterns caused by seizures in epileptic patients. We evaluated 19 patients with PASL. Of these, the 9 affected by high-frequency seizures were observed during the peri-ictal period (within 5hours since the last seizure), while the 10 patients affected by low-frequency seizures were observed in the post-ictal period. For comparison, 17/19 patients were also evaluated with DSC-MRI and CBF/CBV. PASL imaging showed focal vascular changes, which allowed the classification of patients in three categories: 8 patients characterized by increased perfusion, 4 patients with normal perfusion and 7 patients with decreased perfusion. PASL perfusion imaging findings were comparable to those obtained by DSC-MRI. Since PASL is a) sensitive to vascular alterations induced by epileptic seizures, b) comparable to DSC-MRI for detecting perfusion asymmetries, c) potentially capable of detecting time-related perfusion changes, it can be recommended for repeated evaluations, to identify the epileptic focus, and in follow-up and/or therapy-response assessment.

  6. A Shortened Norwegian Adaptation of the Lie Scale for Children (LSC) and the Defensiveness Scale for Children (DSC)

    ERIC Educational Resources Information Center

    Haugen, Richard

    1978-01-01

    Ten items consisting of five DSC items and five LSC items were translated into Norwegian in order (a) to control the verbal anxiety responses from defensive tendencies, (b) to handle the problem of response set (the tendency to answer a questionnaire in a stereotyped way), and (c) to permit research concerning the nature of defensiveness itself.…

  7. Bicellar mixture phase behavior examined by variable-pressure deuterium NMR and ambient pressure DSC.

    PubMed

    Uddin, Md Nasir; Morrow, Michael R

    2010-07-20

    Variable-pressure deuterium nuclear magnetic resonance ((2)H NMR) has been used to study the pressure-temperature phase diagram of bicellar mixtures containing 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC). Spectra were obtained for DMPC-d(54)/DHPC (3:1), DMPC-d(54)/DHPC (4.4:1), DMPC/DHPC-d(22) (3:1), and DMPC/DHPC-d(22) (4.4:1) in the range 10-68 degrees C at ambient pressure, 66 MPa, 102 MPa, and 135 MPa. Isotropic-to-nematic and nematic-to-lamellar transition temperatures were found to rise with pressure at approximately 0.15 and approximately 0.14 degrees C/MPa, respectively, for DMPC-d(54)/DHPC (3:1) and at at approximately 0.19 and approximately 0.18 degrees C/MPa, respectively, for DMPC-d(54)/DHPC (4.4:1). Pressure had little effect on the range of DMPC-d(54) chain orientational order through the nematic phase temperature range, but the behavior of chain orientational order at the nematic-to-lamellar transition was found to vary slightly with pressure. Comparison of differential scanning calorimetry (DSC) observations with ambient-pressure (2)H NMR observations of DMPC-d(54) in the bicellar mixtures suggests that absorption of heat persists for a few degrees above the onset of axially symmetric DMPC-d(54) reorientation.

  8. The glass transition and enthalpy recovery of a single polystyrene ultrathin film using Flash DSC

    NASA Astrophysics Data System (ADS)

    Koh, Yung P.; Simon, Sindee L.

    2017-05-01

    The kinetics of the glass transition are measured for a single polystyrene ultrathin film of 20 nm thickness using Flash differential scanning calorimetry (DSC). Tg is measured over a range of cooling rates from 0.1 to 1000 K/s and is depressed compared to the bulk. The depression decreases with increasing cooling rate, from 12 K lower than the bulk at 0.1 K/s to no significant change at 1000 K/s. Isothermal enthalpy recovery measurements are performed from 50 to 115 °C, and from these experiments, the temperature dependence of the induction time along the glass line is obtained, as well as the temperature dependence of the time scale required to reach equilibrium, providing a measure of the shortest effective glassy relaxation time and the longest effective equilibrium relaxation time, respectively. The induction time for the ultrathin film is found to be similar to the bulk at all temperatures presumably because the Tg values are the same due to the use of a cooling rate of 1000 K/s prior to the enthalpy recovery measurements. On the other hand, the times required to reach equilibrium for the ultrathin film and bulk are similar at 100 °C, and considerably shorter for the ultrathin film at 90 °C, consistent with faster dynamics under nanoconfinement at low temperatures. The magnitude of the "Tg depression" is smaller when using the equilibrium relaxation time from the structural recovery experiment as a measure of the dynamics than when measuring Tg after a cooling experiment. A relaxation map is developed to summarize the results.

  9. The glass transition and enthalpy recovery of a single polystyrene ultrathin film using Flash DSC.

    PubMed

    Koh, Yung P; Simon, Sindee L

    2017-05-28

    The kinetics of the glass transition are measured for a single polystyrene ultrathin film of 20 nm thickness using Flash differential scanning calorimetry (DSC). Tg is measured over a range of cooling rates from 0.1 to 1000 K/s and is depressed compared to the bulk. The depression decreases with increasing cooling rate, from 12 K lower than the bulk at 0.1 K/s to no significant change at 1000 K/s. Isothermal enthalpy recovery measurements are performed from 50 to 115 °C, and from these experiments, the temperature dependence of the induction time along the glass line is obtained, as well as the temperature dependence of the time scale required to reach equilibrium, providing a measure of the shortest effective glassy relaxation time and the longest effective equilibrium relaxation time, respectively. The induction time for the ultrathin film is found to be similar to the bulk at all temperatures presumably because the Tg values are the same due to the use of a cooling rate of 1000 K/s prior to the enthalpy recovery measurements. On the other hand, the times required to reach equilibrium for the ultrathin film and bulk are similar at 100 °C, and considerably shorter for the ultrathin film at 90 °C, consistent with faster dynamics under nanoconfinement at low temperatures. The magnitude of the "Tg depression" is smaller when using the equilibrium relaxation time from the structural recovery experiment as a measure of the dynamics than when measuring Tg after a cooling experiment. A relaxation map is developed to summarize the results.

  10. Crystallization kinetics of orthorhombic paracetamol from supercooled melts studied by non-isothermal DSC.

    PubMed

    Nikolakakis, Ioannis; Kachrimanis, Kyriakos

    2017-02-01

    A simple and highly reproducible procedure was established for the study of orthorhombic paracetamol crystallization kinetics, comprising melting, quench-cooling of the melt and scanning the formed glass by DSC at different heating rates. Results were analyzed on the basis of the mean as well as local values of the Avrami exponent, n, the energy of activation, as well as the Šesták-Berggren two-parameter autocatalytic kinetic model. The mean value of the Avrami kinetic exponent, n, ranged between 3 and 5, indicating deviation from the nucleation and growth mechanism underlying the Johnson-Mehl, Avrami-Kolmogorov (JMAK) model. To verify the extent of the deviation, local values of the Avrami exponent as a function of the volume fraction transformed were calculated. Inspection of the local exponent values indicates that the crystallization mechanism changes over time, possibly reflecting the uncertainty of crystallization onset, instability of nucleation due to an autocatalytic effect of the crystalline phase, and growth anisotropy due to impingement of spherulites in the last stages of crystallization. The apparent energy of activation, Ea, has a rather low mean value, close to 81 kJ/mol, which is in agreement with the observed instability of glassy-state paracetamol. Isoconversional methods revealed that Ea tends to decrease with the volume fraction transformed, possibly because of the different energy demands of nucleation and growth. The exponents of the Šesták-Berggren two-parameter model showed that the crystallized fraction influences the process, confirming the complexity of the crystallization mechanism.

  11. Prediction of the Long-term Efficacy of STA-MCA Bypass by DSC-PI.

    PubMed

    Hui, Li; Hui, Liu; Tong, Han

    2016-01-01

    Superficial temporal artery-middle cerebral artery (STA-MCA) bypass [1,2] is an important and effective type of surgical revascularization that is widely used in the treatment of ischemic cerebral artery disease. However, a means of predicting its postoperative efficacy has not been established [3,4]. The present study analyzes the correlation between preoperative perfusion parameters (obtained using dynamic susceptibility contrast-enhanced perfusion imaging, DSC-PI) and postoperative long-term prognosis (using modified Rankin Scale, mRS scores). The preoperative perfusion parameters were defined by a combination of perfusion-weighted imaging and the Alberta Stroke Program Early Computerized Tomography Score (PWI-ASPECTS) and included cerebral blood flow (CBF)-ASPECTS, cerebral blood volume (CBV)-ASPECTS, mean transit time (MTT)-ASPECTS, and time to peak (TTP)-ASPECTS. Preoperative and postoperative scores were determined for 33 patients that received a unilateral STA-MCA bypass in order to discover the most reliable imaging predictive index as well as to define the threshold value for a favorable clinical outcome. The results showed that all of the PWI-ASPECTS scores were significantly negatively correlated with clinical prognosis. Receiver operating curve (ROC) analysis of the preoperative parameters in relation to long term prognosis showed the area under curve (AUC) was maximal for the CBF-ASPECTS score (P = 0.002). A preoperative score of less than six indicated a poor postoperative prognosis (sensitivity = 74.1%, specificity = 100%, AUC = 0.843). In conclusion, preoperative PWI-ASPECTS scores have been found useful as predictive indexes for the long-term prognosis of STA-MCA bypass patients, with higher scores indicating better postoperative long-term outcomes. As the most valuable prognostic indicator, the preoperative CBF-ASPECTS score has potential for use as a major index in screening and outcome prediction of patients under consideration for STA

  12. Unspecific membrane protein-lipid recognition: combination of AFM imaging, force spectroscopy, DSC and FRET measurements.

    PubMed

    Borrell, Jordi H; Montero, M Teresa; Morros, Antoni; Domènech, Òscar

    2015-11-01

    In this work, we will describe in quantitative terms the unspecific recognition between lactose permease (LacY) of Escherichia coli, a polytopic model membrane protein, and one of the main components of the inner membrane of this bacterium. Supported lipid bilayers of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) (3:1, mol/mol) in the presence of Ca(2+) display lateral phase segregation that can be distinguished by atomic force microscopy (AFM) as well as force spectroscopy. LacY shows preference for fluid (Lα) phases when it is reconstituted in POPE : POPG (3:1, mol/mol) proteoliposomes at a lipid-to-protein ratio of 40. When the lipid-to-protein ratio is decreased down to 0.5, two domains can be distinguished by AFM. While the upper domain is formed by self-segregated units of LacY, the lower domain is constituted only by phospholipids in gel (Lβ) phase. On the one hand, classical differential scanning calorimetry (DSC) measurements evidenced the segregation of a population of phospholipids and point to the existence of a boundary region at the lipid-protein interface. On the other hand, Förster Resonance Energy Transfer (FRET) measurements in solution evidenced that POPE is selectively recognized by LacY. A binary pseudophase diagram of POPE : POPG built from AFM observations enables to calculate the composition of the fluid phase where LacY is inserted. These results are consistent with a model where POPE constitutes the main component of the lipid-LacY interface segregated from the fluid bulk phase where POPG predominates.

  13. AC susceptibility, XRD and DSC studies of Sm 1- xGd xMn 2Si 2 silicides

    NASA Astrophysics Data System (ADS)

    Kervan, S.; Kılıc&,cedil; A.; Gencer, A.

    2004-02-01

    X-ray powder diffraction, AC susceptibility and differential scanning calorimetry (DSC) studies were performed on the polycrystalline Sm 1- xGd xMn 2Si 2 (0⩽ x⩽1) compounds. All compounds investigated crystallize in the body-centered tetragonal ThCr 2Si 2-type structure with the space group I4/mmm. Substitution of Gd for Sm leads to a linear decrease of the lattice constants and the unit cell volume. The lattice constants and the unit cell volume obey Vegard's law. At low temperatures, the rare earth sublattice orders and reconfigures the ordering in the Mn sublattice. The samples with x=0.6 and 0.8 exhibit spin reorientation phenomenon. The Néel temperature TN(Mn) determined by DSC technique and the Curie temperature TC (RE) increase linearly with increasing Gd content x. The results are summarized in the x- T magnetic phase diagram.

  14. The slow relaxation dynamics in active pharmaceutical ingredients studied by DSC and TSDC: Voriconazole, miconazole and itraconazole.

    PubMed

    Ramos, Joaquim J Moura; Diogo, Hermínio P

    2016-03-30

    The slow molecular mobility of three active pharmaceutical drugs (voriconazole, miconazole and itraconazole) has been studied by differential scanning calorimetry (DSC) and thermally stimulated depolarization currents (TSDC). This study yielded the main kinetic features of the secondary relaxations and of the main (glass transition) relaxation, in particular their distribution of relaxation times. The dynamic fragility of the three glass formers was determined from DSC data (using two different procedures) and from TSDC data. According to our results voriconazole behaves as a relatively strong liquid, while miconazole is moderately fragile and itraconazole is a very fragile liquid. There are no studies in this area published in the literature relating to voriconazole. Also not available in the literature is a slow mobility study by dielectric relaxation spectroscopy in the amorphous miconazole. Apart from that, the results obtained are in reasonable agreement with published works using different experimental techniques. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. {beta}{prime} and {beta} precipitation in an Al-Mg alloy studied by DSC and TEM

    SciTech Connect

    Starink; Zahra, A.M.

    1998-06-12

    Precipitation in Al-16 at. % Mg is investigated by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The shape of the {beta}{prime} formation DSC effect is interpreted with a novel theory and the curves obtained on the basis of this new theory fit well to the experimental curves. The s parameter derived from these fits, which is akin to the Avrami parameter n appearing in the Johnson-Mehl-Avrami-Kolmogorov model, is larger than 2.5, indicating that {beta}{prime} precipitation is an autocatalytic process. TEM showed the abundant presence of defects (mostly dislocation loops) but no evidence of nucleation of {beta}{prime} precipitates on these defects. The enthalpies of formation of the {beta} and {beta}{prime} phases are derived as 15.7 and 11.5 kJ per mol Mg, respectively.

  16. Simultaneous screening and detection of pharmaceutical co-crystals by the one-step DSC-FTIR microspectroscopic technique.

    PubMed

    Lin, Shan-Yang

    2016-12-12

    Various methods and analytical techniques for the preparation and identification of pharmaceutical co-crystals have been applied, but these operations require considerable time for the screening and preparation of co-crystals. In this review, a powerful method that combines Fourier-transform infrared (FTIR) microspectroscopy with thermal analysis is introduced. This unique one-step real-time differential scanning calorimetry (DSC)-FTIR microspectroscopic approach has been successfully applied to simultaneously and directly screen and detect pharmaceutical co-crystal formation in systems such as indomethacin-saccharin, indomethacin-nicotinamide, carbamazepine-glutaric-acid, metaxalone-succinic-acid and piroxicam-saccharin. This powerful one-step DSC-FTIR combined technique provides an easy and direct method for one-step screening and qualitative detection of co-crystal formation in real time.

  17. Physicochemical aging mechanisms in soil organic matter assessed by NMR and DSC

    NASA Astrophysics Data System (ADS)

    Schwarz, J.; Jaeger, A.; Bertmer, M.; Schlichting, A.; Leinweber, P.; Schaumann, G. E.

    2009-04-01

    Soil organic matter (SOM) controls a variety of processes occurring at biogeochemical interfaces acting as a highly dynamic matrix. Results from previous studies showed that SOM undergoes physicochemical matrix aging. It was hypothesized that the formation and disruption of water molecule bridges are responsible for this aging process. The objective of this study was to evaluate this hypothesis using three peat samples from different sample sites in Germany: a peat from Rhinluch, 60 km northwest of Berlin, a black peat and a white peat from Fuhrberg near Hannover. The composition determined by pyrolysis field ionisation mass spectrometry was similar for the Rhinluch peat and the Fuhrberg black peat, but showed a distinctly higher carbohydrate content for the Fuhrberg white peat. To elucidate mechanisms of physicochemical matrix aging and to evaluate the hypothesis of water molecule bridges we carried out heating-cooling events in hermetically sealed containers and measured the response by NMR and DSC as a function of time. The heating-cooling event started with heating for 10 minutes at 110 °C followed by rapid cooling and isothermal storage at 19 °C for at least four months. All peats show a non-reversing step transition between 40 °C and 65 °C similar to transitions observed in previous studies. The black peat from Fuhrberg showed an additional step transition between 35 °C and 45 °C. The temperature of the non-reversing step transition immediately decreased by 25 °C in response to the heating-cooling event and slowly re-increased upon isothermal storage within several months. The temperature of the reversing transition showed a similar behaviour but not as strongly as the non-reversing transition. The proton NMR in combination with line separation into Lorentz and Gauss lines was used to differentiate between the different kinds of water. In dependence of the water bridge status the portions of these lines on the total wide line spectrum change; at a

  18. Combination of TREF, high-temperature HPLC, FTIR and HPer DSC for the comprehensive analysis of complex polypropylene copolymers.

    PubMed

    Cheruthazhekatt, Sadiqali; Pijpers, Thijs F J; Mathot, Vincent B F; Pasch, Harald

    2013-11-01

    A novel, powerful analytical technique, preparative temperature rising elution fractionation (prep TREF)/high-temperature (HT)-HPLC/Fourier transform infrared spectroscopy (FTIR)/high-performance differential scanning calorimetry (HPer DSC)), has been introduced to study the correlation between the polymer chain microstructure and the thermal behaviour of various components in a complex impact polypropylene copolymer (IPC). For the comprehensive analysis of this complex material, in a first step, prep TREF is used to produce less complex but still heterogeneous fractions. These chemically heterogeneous fractions are completely separated by using a highly selective chromatographic separation method--high-temperature solvent gradient HPLC. The detailed structural and thermal analysis of the HPLC fractions was conducted by offline coupling of HT-HPLC with FTIR spectroscopy and a novel DSC method--HPer DSC. Three chemically different components were identified in the mid-elution temperature TREF fractions. For the first component, identified as isotactic polypropylene homopolymer by FTIR, the macromolecular chain length is found to be an important factor affecting the melting and crystallisation behaviour. The second component relates to ethylene-propylene copolymer molecules with varying ethylene monomer distributions and propylene tacticity distributions. For the polyethylene component (last eluting component in all semi-crystalline TREF fractions), it was found that branching produced defects in the long crystallisable ethylene sequences that affected the thermal properties. The different species exhibit distinctively different melting and crystallisation behaviour, as documented by HPer DSC. Using this novel approach of hyphenated techniques, the chain structure and melting and crystallisation behaviour of different components in a complex copolymer were investigated systematically.

  19. Characterization of a Friction Stir Weld in Aluminum Alloy 7055 Using Microhardness, Electrical Conductivity, and Differential Scanning Calorimetry (DSC)

    NASA Astrophysics Data System (ADS)

    Bush, Ralph; Kiyota, Michelle; Kiyota, Catherine

    2016-07-01

    Optical microscopy, microhardness, electrical conductivity, and differential scanning calorimetry (DSC) were used to characterize the microstructure, hardness, and precipitate structure as a function of position in a friction stir weld, naturally aged for 10 years, in aluminum alloy 7055. Results are shown for the as-welded/naturally aged condition and for a weld that was post-aged using a -T76 regimen. The grain structure and microhardness results reveal the expected central recrystallized region, a thermo-mechanical affected zone (TMAZ), and heat-affected zone (HAZ) with typical changes in microhardness. DSC scans for the as-welded/naturally aged condition indicate a precipitate structure similar to that of a naturally aged condition in the central recrystallized region. Maximum precipitate coarsening and overaging occurs near the TMAZ/HAZ boundary with reduced precipitate dissolution and coarsening as the distance from the weld increases. The post-weld aging resulted in the transformation of GP zones to more stable precipitates plus coarsening of the more stable η' and η precipitates. A combination of DSC testing and CALPHAD calculations allowed calculation of precipitate volume fraction in the HAZ. The precipitate volume fraction decreased monotonically from 0.052 in the baseline material to 0.044 at the TMAZ/HAZ interface.

  20. Process induced transformations during tablet manufacturing: phase transition analysis of caffeine using DSC and low frequency micro-Raman spectroscopy.

    PubMed

    Hubert, Sébastien; Briancon, Stéphanie; Hedoux, Alain; Guinet, Yannick; Paccou, Laurent; Fessi, Hatem; Puel, François

    2011-11-25

    The phase transition of a model API, caffeine Form I, was studied during tableting process monitored with an instrumented press. The formulation used had a plastic flow behavior according to the Heckel model in the compression pressure range of 70-170 MPa. The quantitative methods of analysis used were Differential Scanning Calorimetry (DSC) and low frequency Micro Raman Spectroscopy (MRS) which was used for the first time for the mapping of polymorphs in tablets. They brought complementary contributions since MRS is a microscopic spectral analysis with a spatial resolution of 5 μm(3) and DSC takes into account a macroscopic fraction (10mg) of the tablet. Phase transitions were present at the surfaces, borders and center of the tablets. Whatever the pressure applied during the compression process, the transition degree of caffeine Form I toward Form II was almost constant. MRS provided higher transition degrees (50-60%) than DSC (20-35%). MRS revealed that caffeine Form I particles were partially transformed in all parts of the tablets at a microscopic scale. Moreover, tablet surfaces showed local higher transition degree compared to the other parts.

  1. Advances in simultaneous DSC-FTIR microspectroscopy for rapid solid-state chemical stability studies: some dipeptide drugs as examples.

    PubMed

    Lin, Shan-Yang; Wang, Shun-Li

    2012-04-01

    The solid-state chemistry of drugs has seen growing importance in the pharmaceutical industry for the development of useful API (active pharmaceutical ingredients) of drugs and stable dosage forms. The stability of drugs in various solid dosage forms is an important issue because solid dosage forms are the most common pharmaceutical formulation in clinical use. In solid-state stability studies of drugs, an ideal accelerated method must not only be selected by different complicated methods, but must also detect the formation of degraded product. In this review article, an analytical technique combining differential scanning calorimetry and Fourier-transform infrared (DSC-FTIR) microspectroscopy simulates the accelerated stability test, and simultaneously detects the decomposed products in real time. The pharmaceutical dipeptides aspartame hemihydrate, lisinopril dihydrate, and enalapril maleate either with or without Eudragit E were used as testing examples. This one-step simultaneous DSC-FTIR technique for real-time detection of diketopiperazine (DKP) directly evidenced the dehydration process and DKP formation as an impurity common in pharmaceutical dipeptides. DKP formation in various dipeptides determined by different analytical methods had been collected and compiled. Although many analytical methods have been applied, the combined DSC-FTIR technique is an easy and fast analytical method which not only can simulate the accelerated drug stability testing but also at the same time enable to explore phase transformation as well as degradation due to thermal-related reactions. This technique offers quick and proper interpretations.

  2. Tg-Confinement Effects in Polymer Thin Films, Nanotubes, and Nanospheres as Measured by DSC, Ellipsometry and Fluorescence

    NASA Astrophysics Data System (ADS)

    Torkelson, John; Tan, Anthony; Chen, Lawrence

    The effect of nanoscale confinement on the glass transition temperature (Tg) of supported and free-standing polymer films has been studied for two decades by various techniques. However, conventional DSC, which is the most common method for measuring Tg of bulk polymers, is not well suited for such measurements. Here, we demonstrate that Tg-confinement effects measured by conventional DSC in nanotubes of polymer supported in anodic aluminum oxide (AAO) templates compare well with with Tg-confinement effects measured in supported polymer films by ellipsometry and fluorescence. We further show that Tg-confinement effect data for nanotubes obtained by fluorescence agree well with data obtained by DSC. Finally, we draw comparisons between the Tg-confinement behavior of nanoprecipitated polymer nanospheres as measured by fluorescence to Tg-confinement effects for both supported and free-standing polymer films. The roles, if any, of confinement dimensionality (1-D vs 2-D vs 3-D) and measurement technique on the observed Tg-confinement effect will be discussed.

  3. Determination of the heat of hydride formation/decomposition by high-pressure differential scanning calorimetry (HP-DSC).

    PubMed

    Rongeat, Carine; Llamas-Jansa, Isabel; Doppiu, Stefania; Deledda, Stefano; Borgschulte, Andreas; Schultz, Ludwig; Gutfleisch, Oliver

    2007-11-22

    Among the thermodynamic properties of novel materials for solid-state hydrogen storage, the heat of formation/decomposition of hydrides is the most important parameter to evaluate the stability of the compound and its temperature and pressure of operation. In this work, the desorption and absorption behaviors of three different classes of hydrides are investigated under different hydrogen pressures using high-pressure differential scanning calorimetry (HP-DSC). The HP-DSC technique is used to estimate the equilibrium pressures as a function of temperature, from which the heat of formation is derived. The relevance of this procedure is demonstrated for (i) magnesium-based compounds (Ni-doped MgH2), (ii) Mg-Co-based ternary hydrides (Mg-CoHx) and (iii) Alanate complex hydrides (Ti-doped NaAlH4). From these results, it can be concluded that HP-DSC is a powerful tool to obtain a good approximation of the thermodynamic properties of hydride compounds by a simple and fast study of desorption and absorption properties under different pressures.

  4. A novel compound DSC suppresses lipopolysaccharide-induced inflammatory responses by inhibition of Akt/NF-κB signalling in macrophages.

    PubMed

    Liu, Xin-Hua; Pan, Li-Long; Jia, Yao-Ling; Wu, Dan; Xiong, Qing-Hui; Wang, Yang; Zhu, Yi-Zhun

    2013-05-15

    A novel compound [4-(2-acetoxy-3-((R)-3-(benzylthio)-1-methoxy-1-oxopropan-2-ylamino)-3-oxopropyl)-1,2-phenylene diacetate (DSC)], derived from Danshensu, exerted cytoprotective effects by anti-oxidative and anti-apoptotic activities in vitro. Herein, we reported the protective effects of DSC on lipopolysaccharide (LPS)-induced inflammatory responses in murine RAW264.7 macrophages and the underlying mechanisms. We showed that DSC concentration-dependently attenuated nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression with less cytotoxicity. Signal transduction studies indicated that DSC significantly inhibited LPS-induced phosphorylation of Akt, but not c-Jun N-terminal kinase 1/2, p38, or extracellular signal-regulated kinase 1/2. Meanwhile, LPS-induced nuclear translocation of nuclear factor-κB (NF-κB) p65 was decreased by DSC. Furthermore, a phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 significantly suppressed LPS-induced NF-κB p65 nuclear translocation, iNOS expression, and NO production, which was also mimicked by pretreatment with DSC. These results suggested that DSC attenuated LPS-induced inflammatory response in macrophages, at least in part, through suppression of PI3K/Akt signaling and NF-κB activation.

  5. Effect of silica fume on hydration of air-cured blended cement pastes measured by DSC/TG analysis

    NASA Astrophysics Data System (ADS)

    Scheinherrová, Lenka; Trník, Anton; Pokorný, Jaroslav; Pavlík, Zbyšek; Černý, Robert

    2017-07-01

    In this paper, we study the influence of silica fume on hydration of cement pastes. Samples were prepared using Portland cement partially replaced by silica fume of 0, 4, and 12 mass%. Analyses were performed using TG/DSC in the temperature range from 25 °C to 1000 °C in an argon atmosphere. The amount of C-S-H gels decreases in time with an increasing amount of silica fume, which is in the contrary to the vaterite/calcite content. The portlandite content decreases with an increasing amount of silica fume which provides the pozzolanic activity.

  6. Prediction of the self-accelerating decomposition temperature (SADT) for liquid organic peroxides from differential scanning calorimetry (DSC) measurements.

    PubMed

    Malow, M; Wehrstedt, K D

    2005-04-11

    We present a prediction (estimation, calculation, screening) method for the estimation of the self-accelerating decomposition temperature (SADT) for liquid organic peroxides from differential scanning calorimetry (DSC) measurements based on the concepts of thermal explosion theory originally introduced by Semonov which are adopted to our problem assuming nth-order reaction kinetics. For the peroxides under investigation, we demonstrate good agreement with the experimental SADT. This method can be used as a quick and easy applicable method for the estimation of the critical temperatures.

  7. Application of a simultaneous TGA-DSC thermal analysis system for high-throughput screening of catalytic activity.

    PubMed

    Loskyll, Jonas; Maier, Wilhelm F; Stoewe, Klaus

    2012-11-12

    We present here the use of a simultaneous TGA/DSC thermal analyzer as a high-throughput reactor system to measure after calibration the heat of reaction and therefore the catalytic activity of heterogeneous catalysts in a fast, reliable and reproducible manner. By coupling the gas outlet of the analyzer with a mass spectrometer via a heated capillary additional data can be acquired. As a test reaction the oxidation of carbon monoxide with synthetic air, using Hopcalite and several transition and noble metals as catalysts, was chosen. The setup presented allows the rapid sequential screening of about 70 catalysts per day.

  8. Relaxation behaviour of D(-)-salicin as studied by Thermally Stimulated Depolarisation Currents (TSDC) and Differential Scanning Calorimetry (DSC).

    PubMed

    Diogo, Hermínio P; Pinto, Susana S; Moura Ramos, Joaquim J

    2008-06-24

    Thermally Stimulated Depolarisation Currents (TSDC) measurements on D(-)-salicin have been carried out in the temperature region from -165 degrees C up to 150 degrees C. The slow molecular mobility was characterised in the crystal and in the glassy state. The value of the steepness index or fragility (T(g)-normalized temperature dependence of the relaxation time) was obtained by Differential Scanning Calorimetry (DSC) from the analysis of the scanning rate dependency of T(g). The existence of an unknown polymorph of salicin is also reported.

  9. Structure and Phase Transitions of Poly (Hexamethylene p,p'-Bibenzoate) as Studied by DSC and Real-Time SAXS/WAXS Employing Synchrotron Radiation

    SciTech Connect

    Katerska, B.; Krasteva, M.; Perez, E.

    2007-04-23

    Real-time small and wide angle X-ray scattering as well as DSC studies were carried out in order to analyzes the structure and phase transitions of liquid crystalline thermotropic poly(methylene p,p' bibenzoat)

  10. Morphology development upon melting of ultrahigh molecular weight polyethylene formed at high pressure by Ultra SAXS and DSC

    NASA Astrophysics Data System (ADS)

    Wang, Zhigang; Wang, Xuehui; Stribeck, Norbert; Hsiao, Benjamin S.; Han, Charles C.

    2001-03-01

    The morphology development on the melting of ultrahigh molecular weight polyethylenes (UHMWPE), formed from melt crystallization at high different pressures, was studied by ultra small-angle X-ray scattering (USAXS)and DSC. The heating rate used was 5C/min. At 41M psi, UHMWPEs show dominant chain-extended lamellae (CEL) at Mw 4MM, 5MM and 6MM. At 30M psi, UHMWPEs show dominant chain-folding lamellae (CFL) at Mw 4MM, 5MM and 6MM. At 35M psi, UHMWPEs show both CEL and CFL at Mw 5MM and 6MM and a dominant CFL at Mw 4MM. With dominant CFL, USAXS shows a measurable long spacing, which increases with temperature. With dominant CEL, USAXS shows an immeasurable long spacing and relatively strong ultra-small angle scattering intensity. The integrated scattering intensity shows an exponential increase with temperature. The thickest CEL and CFL melt at the end of the DSC endotherm, where the USAXS (corrected for melt scattering) shows a diffuse profile only. This CEL or CFL thickness was estimated using an approach based on the single lamella structure factor. The results show a largest thickness about 100nm for CEL and about 50nm for CFL. Acknowledgement: This work was supported by a NSF grant (DMR 9732653).

  11. Formation of Cholesterol Bilayer Domains Precedes Formation of Cholesterol Crystals in Cholesterol/Dimyristoylphosphatidylcholine Membranes: EPR and DSC Studies

    PubMed Central

    Mainali, Laxman; Raguz, Marija; Subczynski, Witold K.

    2013-01-01

    Saturation-recovery EPR along with DSC were used to determine the cholesterol content at which pure cholesterol bilayer domains (CBDs) and cholesterol crystals begin to form in dimyristoylphosphatidylcholine (DMPC) membranes. To preserve compositional homogeneity throughout the membrane suspension, lipid multilamellar dispersions were prepared using a rapid solvent exchange method. The cholesterol content increased from 0 to 75 mol%. With spin-labeled cholesterol analogs it was shown that the CBDs begin to form at ~50 mol% cholesterol. It was confirmed by DSC that the cholesterol solubility threshold for DMPC membranes is detected at ~66 mol% cholesterol. At levels above this cholesterol content, monohydrate cholesterol crystals start to form. The major finding is that formation of CBDs precedes formation of cholesterol crystals. The region of the phase diagram for cholesterol contents between 50 and 66 mol% is described as a structured one-phase region in which CBDs have to be supported by the surrounding DMPC bilayer saturated with cholesterol. Thus, the phase boundary located at 66 mol% cholesterol separates the structured one-phase region (liquid-ordered phase of DMPC with CBDs) from the two-phase region where the structured liquid-ordered phase of DMPC coexists with cholesterol crystals. It is likely that CBDs are precursors of monohydrate cholesterol crystals. PMID:23834375

  12. Determination of microplastic polyethylene (PE) and polypropylene (PP) in environmental samples using thermal analysis (TGA-DSC).

    PubMed

    Majewsky, Marius; Bitter, Hajo; Eiche, Elisabeth; Horn, Harald

    2016-10-15

    Microplastics are increasingly detected in the environment and the consequences on water resources and ecosystems are not clear to date. The present study provides a cost-effective and straightforward method to determine the mass concentrations of polymer types using thermal analysis. Characteristic endothermic phase transition temperatures were determined for seven plastic polymer types using TGA-DSC. Based on that, extracts from wastewater samples were analyzed. Results showed that among the studied polymers, only PE and PP could be clearly identified, while the phase transition signals of the other polymers largely overlap each other. Subsequently, calibration curves were run for PE and PP for qualitative measurements. 240 and 1540mg/m(3) of solid material (12µm to 1mm) was extracted from two wastewater effluent samples of a municipal WWTP of which 34% (81mg/m(3)) and 17% (257mg/m(3)) could be assigned to PE, while PP was not detected in any of the samples. The presented application of TGA-DSC provides a complementary or alternative method to FT-IR analyses for the determination of PE and PP in environmental samples.

  13. The retrogradation properties of glutinous rice and buckwheat starches as observed with FT-IR, 13C NMR and DSC.

    PubMed

    Lian, Xijun; Wang, Changjun; Zhang, Kunsheng; Li, Lin

    2014-03-01

    The experiment was conducted to study the retrogradation properties of glutinous rice and buckwheat starch with wavelengths of maximum absorbance, FT-IR, (13)C NMR, and DSC. The results show that the starches in retrograded glutinous rice starch and glutinous rice amylopectin could not form double helix. The IR results show that protein inhabits in glutinous rice and maize starches in a different way and appearance of C-H symmetric stretching vibration at 2852 cm(-1) in starch might be appearance of protein. Retrogradation untied the protein in glutinous amylopectin. Enthalpies of sweet potato and maize granules are higher than those of their retrograded starches. The (13)C NMR results show that retrogradation of those two starches leads to presence of β-anomers and retrogradation might decompose lipids in glutinous rice amylopectin into small molecules. Glutinous rice starch was more inclined to retrogradation than buckwheat starch. The DSC results show that the second peak temperatures for retrograded glutinous rice and buckwheat starches should be assigned to protein. The SEM results show that an obvious layer structure exists in retrograded glutinous rice amylopectin.

  14. An efficient computational approach to characterize DSC-MRI signals arising from three-dimensional heterogeneous tissue structures.

    PubMed

    Semmineh, Natenael B; Xu, Junzhong; Boxerman, Jerrold L; Delaney, Gary W; Cleary, Paul W; Gore, John C; Quarles, C Chad

    2014-01-01

    The systematic investigation of susceptibility-induced contrast in MRI is important to better interpret the influence of microvascular and microcellular morphology on DSC-MRI derived perfusion data. Recently, a novel computational approach called the Finite Perturber Method (FPM), which enables the study of susceptibility-induced contrast in MRI arising from arbitrary microvascular morphologies in 3D has been developed. However, the FPM has lower efficiency in simulating water diffusion especially for complex tissues. In this work, an improved computational approach that combines the FPM with a matrix-based finite difference method (FDM), which we call the Finite Perturber the Finite Difference Method (FPFDM), has been developed in order to efficiently investigate the influence of vascular and extravascular morphological features on susceptibility-induced transverse relaxation. The current work provides a framework for better interpreting how DSC-MRI data depend on various phenomena, including contrast agent leakage in cancerous tissues and water diffusion rates. In addition, we illustrate using simulated and micro-CT extracted tissue structures the improved FPFDM along with its potential applications and limitations.

  15. [Study on the Effects of Ginsenoside Rb1 on DPPC Bilayers by Using Thermo-Raman Spectrum and DSC].

    PubMed

    Hui, Ge; Liu, Wei; Zhang, Jing-zhou; Zhou, Tie-li; Wang, Si-ming; Zhao, Yu; Zhao, Bing

    2015-08-01

    The research on the interactions between Ginsenosides and biomembranes plays a crucial role in thorough understanding the pharmacological activity and biologyical effect of Chinese medicine Panax ginseng. With the bilayer structure, DPPC often serves as an simulation model of the cell membrane to study the role of drug molecules and cell membranes. Ginsenoside Rb1, one of the most important components of Panaxginseng, playing the significant roles of pharmacological effects and biological properties. Raman and differential scanning calorimetry (DSC) are respectively a powerful tool for discussing the molecular interaction, and a kind of general technology by which researching the bilayer monomer structures and its interactions with drug molecules. However, rarely research reports on the interactions between drug molecules and biomembranes by means of both technologies above. In this paper, the influence of ginsenoside monomer Rb1 on DPPC membrane bilayers was investigated by thermo-Raman and DSC. In Raman spectra, the changes of DPPC molecule have been observed before and after interacted with ginsenoside Rb1, the data analysis indicates three aspects: the O-C-C-N+ polar head group skeleton, C-C stretching vibration area, and the C-H bond stretching vibrarion in terminated methyl group of alkyl chains. The results showed that ginsenoside Rb1 molecule with certain concentration has not changed the gauche conformation of the polar head backbone group in DPPC bilayers, the order of the internal molecular chain and the lateral chain-chain packing have been decreased as the temperature increased, the lateral disposed disorder has been increased. The changes of some thermodynamic constants obtained by DSC experiment such as phase transition temperature (Tm), the temperature at which the transition is half completed (ΔT1/2), and the transition enthalpy normalized per mol of DPPC (AH) have been showed further results of the thermo Raman experiments, with increasing the

  16. PALS and DSC measurements in 8 MeV electron irradiated natural rubber filled with different fillers

    NASA Astrophysics Data System (ADS)

    Mandal, Arunava; Pan, Sandip; Roychowdhury, Anirban; Sengupta, Asmita

    2015-10-01

    The effect of high energy electron irradiation on the microstructure and thermal properties of natural rubber (NR) filled with different fillers at different concentrations are studied. The samples are irradiated with 8 MeV electron beam to a total dose of 100 KGy. The change in free volume size and specific heat due to addition of fillers and irradiation are studied using positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimetry (DSC) respectively. The Positron lifetime spectra are de-convoluted into two components. The longer lived component (τo-Ps) signifies the pick-off annihilation of ortho-positronium (o-Ps) at free volume site which may be related to the radius of the free volume holes. It is observed that the specific heat (Cp) and free volume size are all affected by both irradiation and addition of fillers.

  17. A DSC study on crystalline LaRC TPI powder - A new version with higher initial molecular weight

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung; Bai, Jia-Mo; St. Clair, Terry L.

    1987-01-01

    A new version of crystalline Langley Research Center Thermoplastic Polyimide (LaRC-TPI) imidized powder, which possesses a higher initial molecular weight (MW), has been prepared and characterized. The scheme used for cyclodehydration during the synthesis of this material is described. Evidence of a higher initial MW for the subject LaRC-TPI is supported by both measurements of the inherent viscosity and the DSC thermograms. An initial melting peak at 295 C is noted in the freshly-synthesized sample. The powder can be recrystallized at any elevated temperatures below 340 C, and a single crystalline endothemic peak is always observed after various thermal histories. The heat of fusion for the fresh sample, as represented by the area under the melting peak in the directional scanning calorimeter thermogram, is about 3.9 cal/gm. Comparisons of thermal properties for the subject material are made to those exhibited by the commercial LaRC-TPI powder.

  18. Azide derivatized anticancer agents of Vitamin K 3: X-ray structural, DSC, resonance spectral and API studies

    NASA Astrophysics Data System (ADS)

    Badave, Kirti; Patil, Yogesh; Gonnade, Rajesh; Srinivas, Darbha; Dasgupta, Rajan; Khan, Ayesha; Rane, Sandhya

    2011-12-01

    Compound 1 [1-imino (acetyl hydrazino)-Vitamin K 3], displays valence tautomerically related electronic isomers as Form I and Form II. Form I exhibits 2D packing fragment with 1D ribbon chains of N-H⋯O hydrogen bonds and shows EPR silent features. While Form II is EPR active and exhibits biradical nature with double quantum transitions at g = 2.0040. 1H NMR of compound 2, [1-imino (hydrazino carboxylate)-Vitamin K 3] and Form II exhibit π delocalization via resonance assisted H-bonding [RAHB] effect compared to Form I. Molecular interactions in Form I and II are visualized by DSC. The electronic structures of compounds 1 and 2 have been correlated to their API values by measuring anticancer activities, mitochondrial potentials and DNA shearing patterns. Form II and compound 2 indicate mitochondria mediated apoptosis (˜75% cell death) while Form I causes 35% cell death.

  19. Kinetics of thermolysis of lanthanum nitrate with hexamethylenetetramine: Crystal structure, TG-DSC, impact and friction sensitivity studies, Part-96

    NASA Astrophysics Data System (ADS)

    Nibha; Baranwal, B. P.; Singh, Gurdip; Singh, C. P.; Daniliuc, Constantin G.; Soni, P. K.; Nath, Yogeshwar

    2014-11-01

    The development of high energetic materials includes process ability and the ability to attain insensitive munitions (IM). This paper investigates the preparation of lanthanum metal nitrate complex of hexamethylenetetramine in water at room temperature. This complex of molecular formulae [La (NO3)2(H2O)6] (2HMTA) (NO3-) (H2O) was characterized by X-ray crystallography. Thermal decomposition was investigated using TG, TG-DSC and ignition delay measurements. Kinetic analysis of isothermal TG data has been investigated using model fitting methods as well as model free isoconversional methods. The sensitivity measurements towards mechanical destructive stimuli such as impact and friction were carried out and the complex was found to be insensitive. In order to identify the end product of thermolysis, X-ray diffraction patterns of end product was carried out which proves the formation of La2O3.

  20. X-linked dystonia parkinsonism syndrome (XDP, lubag): disease-specific sequence change DSC3 in TAF1/DYT3 affects genes in vesicular transport and dopamine metabolism.

    PubMed

    Herzfeld, Thilo; Nolte, Dagmar; Grznarova, Maria; Hofmann, Andrea; Schultze, Joachim L; Müller, Ulrich

    2013-03-01

    X-chromosomal dystonia parkinsonism syndrome (XDP, 'lubag') is associated with sequence changes within the TAF1/DYT3 multiple transcript system. Although most sequence changes are intronic, one, disease-specific single-nucleotide change 3 (DSC3), is located within an exon (d4). Transcribed exon d4 occurs as part of multiple splice variants. These variants include exons d3 and d4 spliced to exons of TAF1, and an independent transcript composed of exons d2-d4. Location of DSC3 in exon d4 and utilization of this exon in multiple splice variants suggest an important role of DSC3 in the XDP pathogenesis. To test this hypothesis, we transfected neuroblastoma cells with four expression constructs, including exons d2-d4 [d2-d4/wild-type (wt) and d2-d4/DSC3] and d3-d4 (d3-d4/wt and d3-d4/DSC3). Expression profiling revealed a dramatic effect of DSC3 on overall gene expression. Three hundred and sixty-two genes differed between cells containing d2-d4/wt and d2-d4/DSC3. Annotation clustering revealed enrichment of genes related to vesicular transport, dopamine metabolism, synapse function, Ca(2+) metabolism and oxidative stress. Two hundred and eleven genes were differentially expressed in d3-d4/wt versus d3-d4/DSC3. Annotation clustering highlighted genes in signal transduction and cell-cell interaction. The data show an important role of physiologically occurring transcript d2-d4 in normal brain function. Interference with this role by DSC3 is a likely pathological mechanism in XDP. Disturbance of dopamine function and of Ca(2+) metabolism can explain abnormal movement; loss of protection against reactive oxygen species may account for the neurodegenerative changes in XDP. Although d3-d4 also affect genes potentially related to neurodegenerative processes, their physiologic role as splice variants of TAF1 awaits further exploration.

  1. Automatic twin vessel recrystallizer. Effective purification of acetaminophen by successive automatic recrystallization and absolute determination of purity by DSC.

    PubMed

    Nara, Osamu

    2011-01-24

    I describe an interchangeable twin vessel (J, N) automatic glass recrystallizer that eliminates the time-consuming recovery and recycling of crystals for repeated recrystallization. The sample goes in the dissolution vessel J containing a magnetic stir-bar K; J is clamped to the upper joint H of recrystallizer body D. Empty crystallization vessel N is clamped to the lower joint M. Pure solvent is delivered to the dissolution vessel and the crystallization vessel via the head of the condenser A. Crystallization vessel is heated (P). The dissolution reservoir is stirred and heated by the solvent vapor (F). Continuous outflow of filtrate E out of J keeps N at a stable boiling temperature. This results in efficient dissolution, evaporation and separation of pure crystals Q. Pure solvent in the dissolution reservoir is recovered by suction. Empty dissolution and crystallization vessels are detached. Stirrer magnet is transferred to the crystallization vessel and the role of the vessels are then reversed. Evacuating mother liquor out of the upper twin vessel, the apparatus unit is ready for the next automatic recrystallization by refilling twin vessels with pure solvent. We show successive automatic recrystallization of acetaminophen from diethyl ether obtaining acetaminophen of higher melting temperatures than USP and JP reference standards by 8× automatic recrystallization, 96% yield at each stage. Also, I demonstrate a novel approach to the determination of absolute purity by combining the successive automatic recrystallization with differential scanning calorimetry (DSC) measurement requiring no reference standards. This involves the measurement of the criterial melting temperature T(0) corresponding to the 100% pure material and quantitative ΔT in DSC based on the van't Hoff law of melting point depression. The purity of six commercial acetaminophen samples and reference standards and an eight times recrystallized product evaluated were 98.8 mol%, 97.9 mol%, 99

  2. Inclusion complexes of cypermethrin and permethrin with monochlorotriazinyl-beta-cyclodextrin: a combined spectroscopy, TG/DSC and DFT study.

    PubMed

    Yao, Qi; You, Bin; Zhou, Shuli; Chen, Meng; Wang, Yujiao; Li, Wei

    2014-01-03

    The suitable size hydrophobic cavity and monochlorotriazinyl group as a reactive anchor make MCT-β-CD to be widely used in fabric finishing. In this paper, the inclusion complexes of monochlorotriazinyl-beta-cyclodextrin (MCT-β-CD) with cypermethrin (CYPERM) and permethrin (PERM) are synthesized and analyzed by TG/DSC, FT-IR and Raman spectroscopy. TG/DSC reveals that the decomposed temperatures of inclusion complexes are lower by 25-30 °C than that of physical mixtures. DFT calculations in conjunction with FT-IR and Raman spectral analyses are used to study the structures of MCT-β-CD and their inclusion complexes. Four isomers of trisubstituted MCT-β-CD are designed and DFT calculations reveal that 1,3,5-trisubstituted MCT-β-CD has the lowest energy and can be considered as main component of MCT-β-CD. The ground-state geometries, vibrational wavenumbers, IR and Raman intensities of MCT-β-CD and their inclusion complexes were calculated at B3LYP/6-31G (d) level of theory. Upon examining the optimized geometry of inclusion complex, we find that the CYPERM and PERM are inserted into the toroid of MCT-β-CD from the larger opening. The band at 1646 cm(-1) in IR and at 1668 cm(-1) in Raman spectrum reveals that monochloroazinyl group of MCT-β-CD exists in ketone form but not in anion form. The noticeable IR and Raman shift of phenyl reveals that these two benzene rings of CYPERM and PERM stays inside the cavity of MCT-β-CD and has weak interaction with MCT-β-CD. This spectroscopy conclusion is consistent with theoretical predicted structure.

  3. Inhibitors of thermally induced burn incidents – characterization by microbiological procedure, electrophoresis, SEM, DSC and IR spectroscopy.

    PubMed

    Pielesz, Anna; Machnicka, Alicja; Gawłowski, Andrzej; Fabia, Janusz; Sarna, Ewa; Biniaś, Włodzimierz

    2015-07-07

    Differential scanning calorimetry (DSC) and thermogravimetric (TGA) investigations, acetate electrophoresis (CAE), Fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM) analysis and microbiological procedures were all carried out after heating the samples to a temperature sufficient for simulating a burn incident. In particular, the purpose of the present study was to analyze the effect of antioxidants, such as fucoidan from brown seaweed and flame-retardant cyclic organophosphates and phosphonates, on an organic chicken skin that gets changed by a burn incident. DSC was considered to be a useful tool in assessing in vitro temperature-mediated cross-linking; an innovative analytical conclusion was obtained from the experimentation described in the paper. FTIR tests revealed that heating a dry organic chicken skin to the boiling point leads to the disappearance of a wide band in the 1650-1550 cm(-1) area or the conversion of a band, which may be attributed to the intermolecular β-sheet aggregates. Fucoidan from brown seaweed and flame-retardant cyclic organophosphates and phosphonates probably bind with the collagen that is changed by the burn (in addition to the influence of antioxidant solutions on samples of a blank or not boiled organic chicken skin) incident forming a polymer film with the collagen of the chicken skin surface (SEM analysis), decreasing the aggregation process and native collagen recovery. Good bacteriostatic properties were determined for fucoidan samples from brown seaweed and flame-retardant cyclic organophosphates and phosphonates against the pathogenic bacteria Escherichia coli and Staphylococcus aureus. Thus, it was observed that the fucoidan incorporated into collagen films can be used as a therapeutically active biomaterial that speeds up the wound-healing process.

  4. Regional and voxel-wise comparisons of blood flow measurements between dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) and arterial spin labeling (ASL) in brain tumors.

    PubMed

    White, Carissa M; Pope, Whitney B; Zaw, Taryar; Qiao, Joe; Naeini, Kourosh M; Lai, Albert; Nghiemphu, Phioanh L; Wang, J J; Cloughesy, Timothy F; Ellingson, Benjamin M

    2014-01-01

    The objective of the current study was to evaluate the regional and voxel-wise correlation between dynamic susceptibility contrast (DSC) and arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) measurement of cerebral blood flow (CBF) in patients with brain tumors. Thirty patients with histologically verified brain tumors were evaluated in the current study. DSC-MRI was performed by first using a preload dose of gadolinium contrast, then collecting a dynamic image acquisition during a bolus of contrast, followed by posthoc contrast agent leakage correction. Pseudocontinuous ASL was collected using 30 pairs of tag and control acquisition using a 3-dimensional gradient-echo spin-echo (GRASE) acquisition. All images were registered to a high-resolution anatomical atlas. Average CBF measurements within regions of contrast-enhancement and T2 hyperintensity were evaluated between the two modalities. Additionally, voxel-wise correlation between CBF measurements obtained with DSC and ASL were assessed. Results demonstrated a positive linear correlation between DSC and ASL measurements of CBF when regional average values were compared; however, a statistically significant voxel-wise correlation was only observed in around 30-40% of patients. These results suggest DSC and ASL may provide regionally similar, but spatially different measurements of CBF.

  5. Differential scanning calorimetry (DSC) as a tool for probing the reactivity of polyynes relevant to hexadehydro-Diels-Alder (HDDA) cascades.

    PubMed

    Woods, Brian P; Hoye, Thomas R

    2014-12-19

    The differential scanning calorimetry (DSC) behavior of a number of alkyne-rich compounds is described. The DSC trace for each compound exhibits an exothermic event at a characteristic onset temperature. For the tri- and tetraynes whose [4 + 2] HDDA reactivity in solution has been determined, these onset temperatures show a strong correlation with the cyclization activation energy. The studies reported here exemplify how the data available through this operationally simple analytical technique can give valuable insights into the thermal behavior of small molecules.

  6. Examination of fluorination effect on physical properties of saturated long-chain alcohols by DSC and Langmuir monolayer.

    PubMed

    Nakahara, Hiromichi; Nakamura, Shohei; Okahashi, Yoshinori; Kitaguchi, Daisuke; Kawabata, Noritake; Sakamoto, Seiichi; Shibata, Osamu

    2013-02-01

    Partially fluorinated long-chain alcohols have been newly synthesized from a radical reaction, which is followed by a reductive reaction. The fluorinated alcohols have been investigated by differential scanning calorimetry (DSC) and compression isotherms in a Langmuir monolayer state. Their melting points increase with an increase in chain length due to elongation of methylene groups. However, the melting points for the alcohols containing shorter fluorinated moieties are lower than those for the typical hydrogenated fatty alcohols. Using the Langmuir monolayer technique, surface pressure (π)-molecular area (A) and surface potential (ΔV)-A isotherms of monolayers of the fluorinated alcohols have been measured in the temperature range from 281.2 to 303.2K. In addition, a compressibility modulus (Cs(-1)) is calculated from the π-A isotherms. Four kinds of the alcohol monolayers show a phase transition (π(eq)) from a disordered to an ordered state upon lateral compression. The π(eq) values increase linearly with increasing temperatures. A slope of π(eq) against temperature for the alcohols with shorter fluorocarbons is unexpectedly larger than that for the corresponding fatty alcohols. Generally, fluorinated amphiphiles have a greater thermal stability (or resistance), which is a characteristic of highly fluorinated or perfluorinated compounds. Herein, however, the alcohols containing perfluorobutylated and perfluorohexylated chains show the irregular thermal behavior in both the solid and monolayer states. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Synthesis of dry AgPO3 glass and characterization by Raman, IR and m-DSC

    NASA Astrophysics Data System (ADS)

    Novita, D.; Boolchand, P.

    2008-03-01

    Glass transition temperature of titled glass apparently vary over a wide range, 163 C< Tg< 254 C depending on the humidity of the ambient environment in which precursors are handled^1. We have examined a set of 4 samples (1(181 C),2(203 C), 3(242.7 C), 4(254 C) with different Tgs indicated in parenthesis, in m-DSC, Raman and IR experiments to elucidate the role of bonded water. Our results show that the glass transition endotherm of sample 4 (dry) is characteristic of a stressed-rigid glass, while that of sample 1 (wet) of a flexible glass. Although Raman scattering of samples 1 and 4 look superficially similar, they are different in details; the Boson peak in sample 4 has a stronger intensity than in sample 1. IR reflectance signal strength in the mid-IR range is weaker for sample 4 than for sample 1, and furthermore differs in details. These results show that presence of water disrupts the P-O-P chain network by replacing bridging O with terminal OH^- ends. And once water is bonded, it is difficult to remove it completely. These results will be compared to previous reports in the field. ^1 D.I.Novita and P.Boolchand Phys. Rev. B (in press) * Supported by NSF grant DMR 04-56472

  8. Effect of chirality on PVP/drug interaction within binary physical mixtures of ibuprofen, ketoprofen, and naproxen: a DSC study.

    PubMed

    Ivanov, Ivan T; Tsokeva, Zhivka

    2009-08-01

    We report on the thermal behavior of freshly prepared binary drug/polymer physical mixtures that contained ibuprofen, ketoprofen, or naproxen as a drug, and polyvinylpyrrolidone (PVP), hydroxyethylcellulose (HEC), or methylcellulose (MC) as excipient. At 6-10 degrees C/min heating rates the DSC detected a sharp, single endotherm that corresponds to the melting of drug. On heating physical mixtures of PVP and racemic ibuprofen or ketoprofen at lower heating rates, another endotherm was registered in front of the original one. To observe the additional endotherm, specific minimal values of the heating rate and of PVP weight fraction were needed; for ibuprofen and ketoprofen they were 1.5 and 2.0 degrees C/min, and 5 and 15% (w/w), respectively. At greater PVP weight fractions the top temperatures, T(mp), of both peaks were reduced almost linearly indicating strong solid-state interfacial reaction between the drug particles and PVP matrix. The additional endotherm was abolished at greater heating rates (2 degrees C/min for ibuprofen, 3 degrees C/min for ketoprofen), by replacing the racemate with respective S+-enantiomer and by replacing PVP with HEC and MC. Hence, the possible inclusion of enantioselective component within the PVP/drug interaction, responsible for the amorphization of physical mixture over storage, is assumed.

  9. Thermal Hazard Evaluation of Cumene Hydroperoxide-Metal Ion Mixture Using DSC, TAM III, and GC/MS.

    PubMed

    You, Mei-Li

    2016-04-28

    Cumene hydroperoxide (CHP) is widely used in chemical processes, mainly as an initiator for the polymerization of acrylonitrile-butadiene-styrene. It is a typical organic peroxide and an explosive substance. It is susceptible to thermal decomposition and is readily affected by contamination; moreover, it has high thermal sensitivity. The reactor tank, transit storage vessel, and pipeline used for manufacturing and transporting this substance are made of metal. Metal containers used in chemical processes can be damaged through aging, wear, erosion, and corrosion; furthermore, the containers might release metal ions. In a metal pipeline, CHP may cause incompatibility reactions because of catalyzed exothermic reactions. This paper discusses and elucidates the potential thermal hazard of a mixture of CHP and an incompatible material's metal ions. Differential scanning calorimetry (DSC) and thermal activity monitor III (TAM III) were employed to preliminarily explore and narrate the thermal hazard at the constant temperature environment. The substance was diluted and analyzed by using a gas chromatography spectrometer (GC) and gas chromatography/mass spectrometer (GC/MS) to determine the effect of thermal cracking and metal ions of CHP. The thermokinetic parameter values obtained from the experiments are discussed; the results can be used for designing an inherently safer process. As a result, the paper finds that the most hazards are in the reaction of CHP with Fe(2+). When the metal release is exothermic in advance, the system temperature increases, even leading to uncontrollable levels, and the process may slip out of control.

  10. Interaction of poly(L-lysines) with negatively charged membranes: an FT-IR and DSC study.

    PubMed

    Schwieger, Christian; Blume, Alfred

    2007-04-01

    The influence of the binding of poly(L-lysine) (PLL) to negatively charged membranes containing phosphatidylglycerols (PG) was studied by DSC and FT-IR spectroscopy. We found a general increase in the main transition temperature as well as increase in hydrophobic order of the membrane upon PLL binding. Furthermore we observed stronger binding of hydration water to the lipid head groups after PLL binding. The secondary structure of the PLL after binding was studied by FT-IR spectroscopy. We found that PLL binds in an alpha-helical conformation to negatively charged DPPG membranes or membranes with DPPG-rich domains. Moreover we proved that PLL binding induces domain formation in the gel state of mixed DPPC/DPPG or DMPC/DPPG membranes as well as lipid remixing in the liquid-crystalline state. We studied these effects as a function of PLL chain length and found a significant dependence of the secondary structure, phase transition temperature and domain formation capacity on PLL chain length and also a correlation between the peptide secondary structure and the phase transition temperature of the membrane. We present a system in which the membrane phase transition triggers a highly cooperative secondary structure transition of the membrane-bound peptide from alpha-helix to random coil.

  11. Assessing tumor cytoarchitecture using multi-echo DSC-MRI derived measures of the Transverse Relaxivity at Tracer Equilibrium (TRATE)

    PubMed Central

    Semmineh, Natenael B; Xu, Junzhong; Skinner, Jack T; Xie, Jingping; Li, Hua; Ayers, Gregory; Quarles, C Chad

    2014-01-01

    Purpose In brain tumor dynamic susceptibility contrast (DSC)-MRI studies, multi-echo acquisition methods are used to quantify the dynamic changes in T1 and T2* that occur when contrast agent (CA) extravasates. Such methods also enable the estimation of the effective tissue CA transverse relaxivity. The goal of this study was to evaluate the sensitivity of the Transverse Relaxivity at Tracer Equilibrium (TRATE) to tumor cytoarchitecture. Theory and Methods Computational and in vitro studies were used to evaluate the biophysical basis of TRATE. In 9L, C6 and human brain tumors, TRATE, the apparent diffusion coefficient (ADC), the CA transfer constant (Ktrans), the extravascular extracellular volume fraction (ve) and histological data were compared. Results Simulations and in vitro results indicate that TRATE is highly sensitive to variations in cellular properties such as cell size and density. The histologic cell density and TRATE values were significantly higher in 9L tumors as compared to C6 tumors. In animal and human tumors, a voxel-wise comparison of TRATE with ADC, ve, and Ktrans maps showed low spatial correlation. Conclusion The assessment of TRATE is clinically feasible and its sensitivity to tissue cytoarchitectural features not present in other imaging methods indicate that it could potentially serve as a unique structural signature or “trait” of cancer. PMID:25227668

  12. Poly(ethylene oxide) irradiated in the solid state, melt and aqueous solution—a DSC and WAXD study

    NASA Astrophysics Data System (ADS)

    Jurkin, Tanja; Pucić, Irina

    2012-09-01

    Interactions of the aggregate state of poly(ethylene oxide), PEO, and γ-irradiation conditions (total dose, atmosphere) on its thermal and crystalline properties were investigated by DSC and WAXD taking into account sample molecular mass and form. In PEO irradiated in the solid state and in the presence of oxygen, chain scission dominated over concurrent crosslinking up to 200 kGy, particularly in PEO powders, due to a large surface being in contact with air. In solid samples the degree of crystallinity and crystallite size increased with the dose up to 50 kGy, probably not just due to partial crystallization upon degradation of amorphous phase, but to recrystallization of broken tie molecules. The least changes in crystallinity and phase transformation temperatures occurred in solid films. A substantial decrease in crystallinity and transformation temperatures without the initial crystallinity increase was achieved in samples that were amorphous on irradiation, at temperatures above the PEO melting temperature and in aqueous solutions. Radiation crosslinking of the PEO aqueous solution in an inert atmosphere is the most suitable way to obtain a lower degree of crystallinity and phase transformation temperatures while preserving mechanical properties.

  13. FT-IR and DSC studies of poly(vinylidene chloride-co-acrylonitrile) complexed with LiBF4

    NASA Astrophysics Data System (ADS)

    Shanthi, M.; Mathew, Chithra M.; Ulaganathan, M.; Rajendran, S.

    2013-05-01

    Poly(vinylidene chloride-co-acrylonitrile) (PVdC-co-AN) based solvent free electrolytes were prepared for different compositions of PVdC-co-AN and LiBF4 using solution casting technique. The ionic conductivity, thermal behavior, complexation and structure of polymer electrolytes have been investigated as a function of LiBF4 content at different weight ratios. DSC studies revealed that the glass transition temperature Tg decreases with the increase of salt concentration up to an optimum level. The change in the glass transition temperature (Tg) with respect to the LiBF4 concentration is reflected in the bulk resistance of the electrolytes and the sample containing 6 wt.% of LiBF4 exhibited minimum bulk resistance compared to other samples. FT-IR studies confirm the interaction of polymer and salt which is mainly between Li-cation and nitrogen atom of Ctbnd N group. The crystalline phase of polymer host is completely changed on the addition of Li salt.

  14. FT-IR and DSC studies of poly(vinylidene chloride-co-acrylonitrile) complexed with LiBF4.

    PubMed

    Shanthi, M; Mathew, Chithra M; Ulaganathan, M; Rajendran, S

    2013-05-15

    Poly(vinylidene chloride-co-acrylonitrile) (PVdC-co-AN) based solvent free electrolytes were prepared for different compositions of PVdC-co-AN and LiBF4 using solution casting technique. The ionic conductivity, thermal behavior, complexation and structure of polymer electrolytes have been investigated as a function of LiBF4 content at different weight ratios. DSC studies revealed that the glass transition temperature Tg decreases with the increase of salt concentration up to an optimum level. The change in the glass transition temperature (Tg) with respect to the LiBF4 concentration is reflected in the bulk resistance of the electrolytes and the sample containing 6 wt.% of LiBF4 exhibited minimum bulk resistance compared to other samples. FT-IR studies confirm the interaction of polymer and salt which is mainly between Li-cation and nitrogen atom of C≡N group. The crystalline phase of polymer host is completely changed on the addition of Li salt. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. A Homozygous Nonsense Mutation in the Human Desmocollin-3 (DSC3) Gene Underlies Hereditary Hypotrichosis and Recurrent Skin Vesicles

    PubMed Central

    Ayub, Muhammad; Basit, Sulman; Jelani, Musharraf; Rehman, Fazal Ur; Iqbal, Muhammad; Yasinzai, Masoom; Ahmad, Wasim

    2009-01-01

    Desmosomes are the major players in epidermis and cardiac muscles and contribute to intercellular binding and maintenance of tissue integrity. Two important constituents of desmosomes are transmembrane cadherins named desmogleins and desmocollins. The critical role of these desmosomal proteins in epithelial integrity has been illustrated by their disruption in mouse models and human diseases. In the present study, we have investigated a large family from Afghanistan in which four individuals are affected with hereditary hypotrichosis and the appearance of recurrent skin vesicle formation. All four affected individuals showed sparse and fragile hair on scalp, as well as absent eyebrows and eyelashes. Vesicles filled with thin, watery fluid were observed on the affected individuals' scalps and on most of the skin covering their bodies. A scalp-skin biopsy of an affected individual showed mild hair-follicle plugging. Candidate-gene-based homozygosity linkage mapping assigned the disease locus to 8.30 cM (8.51 Mbp) on chromosome 18q12.1. A maximum multipoint LOD score of 3.30 (θ = 0.00) was obtained at marker D18S877. Sequence analysis of four desmoglein and three desmocollin genes, contained within the linkage interval, revealed a homozygous nonsense mutation (c.2129T>G [p.Leu710X]) in exon-14 of the desmocollin-3 (DSC3) gene. PMID:19765682

  16. Dysspondyloenchondromatosis (DSC) associated with COL2A1 mutation: Clinical and radiological overlap with spondyloepimetaphyseal dysplasia-Strudwick type (SEMD-S).

    PubMed

    Merrick, Blair; Calder, Alistair; Wakeling, Emma

    2015-12-01

    Dysspondyloenchondromatosis (DSC) is a rare skeletal dysplasia characterized by enchondroma-like lesions and anisospondyly. The former leads to discrepancies in limb length, and the latter, to progressive kyphoscoliosis. Two recent cases have highlighted the genetic heterogeneity of DSC, one demonstrating the presence and, the other, the absence of a COL2A1 mutation. This may have important clinical implications, for example, screening for complications including atlanto-axial instability associated with type II collagenopathies, as well as long-term patient management. We report on a case with radiographic features of DSC with overlap into the type II collagenopathy spondyloepimetaphyseal dysplasia, Strudwick type, who was found to carry a novel heterozygous mutation in the COL2A1 gene. Testing for COL2A1 mutations should be performed in all patients with radiological features of DSC. Further research is needed to identify the underlying molecular cause in cases where no COL2A1 mutation is identified. © 2015 Wiley Periodicals, Inc.

  17. Spiral Perfusion Imaging With Consecutive Echoes (SPICE™) for the Simultaneous Mapping of DSC- and DCE-MRI Parameters in Brain Tumor Patients: Theory and Initial Feasibility

    PubMed Central

    Paulson, Eric S.; Prah, Douglas E.; Schmainda, Kathleen M.

    2017-01-01

    Dynamic contrast-enhanced (DCE) and dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) are the perfusion imaging techniques most frequently used to probe the angiogenic character of brain neoplasms. With these methods, T1- and T2/T2*-weighted imaging sequences are used to image the distribution of gadolinium (Gd)-based contrast agents. However, it is well known that Gd exhibits combined T1, T2, and T2* shortening effects in tissue, and therefore, the results of both DCE- and DSC-MRI can be confounded by these opposing effects. In particular, residual susceptibility effects compete with T1 shortening, which can confound DCE-MRI parameters, whereas dipolar T1 and T2 leakage and residual susceptibility effects can confound DSC-MRI parameters. We introduce here a novel perfusion imaging acquisition and postprocessing method termed Spiral Perfusion Imaging with Consecutive Echoes (SPICE) that can be used to simultaneously acquire DCE- and DSC-MRI data, which requires only a single dose of the Gd contrast agent, does not require the collection of a precontrast T1 map for DCE-MRI processing, and eliminates the confounding contrast agent effects due to contrast extravasation. A detailed mathematical description of SPICE is provided here along with a demonstration of its utility in patients with high-grade glioma. PMID:28090589

  18. Spiral Perfusion Imaging With Consecutive Echoes (SPICE™) for the Simultaneous Mapping of DSC- and DCE-MRI Parameters in Brain Tumor Patients: Theory and Initial Feasibility.

    PubMed

    Paulson, Eric S; Prah, Douglas E; Schmainda, Kathleen M

    2016-12-01

    Dynamic contrast-enhanced (DCE) and dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) are the perfusion imaging techniques most frequently used to probe the angiogenic character of brain neoplasms. With these methods, T1- and T2/T2*-weighted imaging sequences are used to image the distribution of gadolinium (Gd)-based contrast agents. However, it is well known that Gd exhibits combined T1, T2, and T2* shortening effects in tissue, and therefore, the results of both DCE- and DSC-MRI can be confounded by these opposing effects. In particular, residual susceptibility effects compete with T1 shortening, which can confound DCE-MRI parameters, whereas dipolar T1 and T2 leakage and residual susceptibility effects can confound DSC-MRI parameters. We introduce here a novel perfusion imaging acquisition and postprocessing method termed Spiral Perfusion Imaging with Consecutive Echoes (SPICE) that can be used to simultaneously acquire DCE- and DSC-MRI data, which requires only a single dose of the Gd contrast agent, does not require the collection of a precontrast T1 map for DCE-MRI processing, and eliminates the confounding contrast agent effects due to contrast extravasation. A detailed mathematical description of SPICE is provided here along with a demonstration of its utility in patients with high-grade glioma.

  19. Biophysical characterization of the honeybee DSC1 orthologue reveals a novel voltage-dependent Ca2+ channel subfamily: CaV4

    PubMed Central

    Gosselin-Badaroudine, Pascal; Moreau, Adrien; Simard, Louis; Cens, Thierry; Rousset, Matthieu; Collet, Claude; Charnet, Pierre

    2016-01-01

    Bilaterian voltage-gated Na+ channels (NaV) evolved from voltage-gated Ca2+ channels (CaV). The Drosophila melanogaster Na+ channel 1 (DSC1), which features a D-E-E-A selectivity filter sequence that is intermediate between CaV and NaV channels, is evidence of this evolution. Phylogenetic analysis has classified DSC1 as a Ca2+-permeable Na+ channel belonging to the NaV2 family because of its sequence similarity with NaV channels. This is despite insect NaV2 channels (DSC1 and its orthologue in Blatella germanica, BSC1) being more permeable to Ca2+ than Na+. In this study, we report the cloning and molecular characterization of the honeybee (Apis mellifera) DSC1 orthologue. We reveal several sequence variations caused by alternative splicing, RNA editing, and genomic variations. Using the Xenopus oocyte heterologous expression system and the two-microelectrode voltage-clamp technique, we find that the channel exhibits slow activation and inactivation kinetics, insensitivity to tetrodotoxin, and block by Cd2+ and Zn2+. These characteristics are reminiscent of CaV channels. We also show a strong selectivity for Ca2+ and Ba2+ ions, marginal permeability to Li+, and impermeability to Mg2+ and Na+ ions. Based on current ion channel nomenclature, the D-E-E-A selectivity filter, and the properties we have uncovered, we propose that DSC1 homologues should be classified as CaV4 rather than NaV2. Indeed, channels that contain the D-E-E-A selectivity sequence are likely to feature the same properties as the honeybee’s channel, namely slow activation and inactivation kinetics and strong selectivity for Ca2+ ions. PMID:27432995

  20. Biophysical characterization of the honeybee DSC1 orthologue reveals a novel voltage-dependent Ca2+ channel subfamily: CaV4.

    PubMed

    Gosselin-Badaroudine, Pascal; Moreau, Adrien; Simard, Louis; Cens, Thierry; Rousset, Matthieu; Collet, Claude; Charnet, Pierre; Chahine, Mohamed

    2016-08-01

    Bilaterian voltage-gated Na(+) channels (NaV) evolved from voltage-gated Ca(2+) channels (CaV). The Drosophila melanogaster Na(+) channel 1 (DSC1), which features a D-E-E-A selectivity filter sequence that is intermediate between CaV and NaV channels, is evidence of this evolution. Phylogenetic analysis has classified DSC1 as a Ca(2+)-permeable Na(+) channel belonging to the NaV2 family because of its sequence similarity with NaV channels. This is despite insect NaV2 channels (DSC1 and its orthologue in Blatella germanica, BSC1) being more permeable to Ca(2+) than Na(+) In this study, we report the cloning and molecular characterization of the honeybee (Apis mellifera) DSC1 orthologue. We reveal several sequence variations caused by alternative splicing, RNA editing, and genomic variations. Using the Xenopus oocyte heterologous expression system and the two-microelectrode voltage-clamp technique, we find that the channel exhibits slow activation and inactivation kinetics, insensitivity to tetrodotoxin, and block by Cd(2+) and Zn(2+) These characteristics are reminiscent of CaV channels. We also show a strong selectivity for Ca(2+) and Ba(2+) ions, marginal permeability to Li(+), and impermeability to Mg(2+) and Na(+) ions. Based on current ion channel nomenclature, the D-E-E-A selectivity filter, and the properties we have uncovered, we propose that DSC1 homologues should be classified as CaV4 rather than NaV2. Indeed, channels that contain the D-E-E-A selectivity sequence are likely to feature the same properties as the honeybee's channel, namely slow activation and inactivation kinetics and strong selectivity for Ca(2+) ions.

  1. Effects of pH and buffer concentration on the thermal stability of etanercept using DSC and DLS.

    PubMed

    Kim, Nam Ah; An, In Bok; Lim, Dae Gon; Lim, Jun Yeul; Lee, Sang Yeol; Shim, Woo Sun; Kang, Nae-Gyu; Jeong, Seong Hoon

    2014-01-01

    The protein size, electrical interaction, and conformational stability of etanercept (marketed as Enbrel®) were examined by thermodynamic and light scattering methods with changing pH and buffer concentration. As pH of etanercept increased from pH 6.6 to 8.6, electrical repulsion in the solution increased, inducing a decrease in protein size. However, the size changed less in high buffer concentration and irreversible aggregation issues were not observed; in contrast, aggregates of about 1000 nm were observed in low buffer concentration at the pH range. Three significant unfolding transitions (Tm) were observed by differential scanning calorimetry (DSC). Unlikely to Tm1, Tm2 and Tm3 were increased as the pH increased. Higher Tm at high buffer concentration was observed, indicating increased conformational stability. The apparent activation energy of unfolding was further investigated since continuous increase of Tm2 and Tm3 was not sufficient to determine optimal conditions. A higher energy barrier was calculated at Tm2 than at Tm3. In addition, the energy barriers were the highest at pH from 7.4 to 7.8 where higher Tm1 was also observed. Therefore, the conformational stability of protein solution significantly changed with pH dependent steric repulsion of neighboring protein molecules. An optimized pH range was obtained that satisfied the stability of all three domains. Electrostatic circumstances and structural interactions resulted in irreversible aggregation at low buffer concentrations and were suppressed by increasing the concentration. Therefore, increased buffer concentration is recommended during protein formulation development, even in the earlier stages of investigation, to avoid protein instability issues.

  2. SU-D-18C-02: Feasibility of Using a Short ASL Scan for Calibrating Cerebral Blood Flow Obtained From DSC-MRI

    SciTech Connect

    Wang, P; Chang, T; Huang, K; Yeh, C; Chien, C; Wai, Y; Lee, T; Liu, H

    2014-06-01

    Purpose: This study aimed to evaluate the feasibility of using a short arterial spin labeling (ASL) scan for calibrating the dynamic susceptibility contrast- (DSC-) MRI in a group of patients with internal carotid artery stenosis. Methods: Six patients with unilateral ICA stenosis enrolled in the study on a 3T clinical MRI scanner. The ASL-cerebral blood flow (-CBF) maps were calculated by averaging different number of dynamic points (N=1-45) acquired by using a Q2TIPS sequence. For DSC perfusion analysis, arterial input function was selected to derive the relative cerebral blood flow (rCBF) map and the delay (Tmax) map. Patient-specific CF was calculated from the mean ASL- and DSC-CBF obtained from three different masks: (1)Tmax< 3s, (2)combined gray matter mask with mask 1, (3)mask 2 with large vessels removed. One CF value was created for each number of averages by using each of the three masks for calibrating the DSC-CBF map. The CF value of the largest number of averages (NL=45) was used to determine the acceptable range(< 10%, <15%, and <20%) of CF values corresponding to the minimally acceptable number of average (NS) for each patient. Results: Comparing DSC CBF maps corrected by CF values of NL (CBFL) in ACA, MCA and PCA territories, all masks resulted in smaller CBF on the ipsilateral side than the contralateral side of the MCA territory(p<.05). The values obtained from mask 1 were significantly different than the mask 3(p<.05). Using mask 3, the medium values of Ns were 4(<10%), 2(<15%) and 2(<20%), with the worst case scenario (maximum Ns) of 25, 4, and 4, respectively. Conclusion: This study found that reliable calibration of DSC-CBF can be achieved from a short pulsed ASL scan. We suggested use a mask based on the Tmax threshold, the inclusion of gray matter only and the exclusion of large vessels for performing the calibration.

  3. Laser Raman, XRD, DSC and Ac-Impedance Analysis of Polymer Blend Electrolyte Based on Eco-Friendly Pva-Pvp Blend with NH4NO3

    NASA Astrophysics Data System (ADS)

    Rajeswari, N.; Selvasekarapandian, S.; Prabaharan, S. R. S.; Kawamura, J.; Iwai, Y.; Karthikeyan, S.

    2013-07-01

    Proton conducting polymer blend electrolytes have attractive interest because of their advantages such as processability, flexibility, electrochemical stability, easy handling and their applications to a variety of electrochemical devices such as fuel cells, chemical sensor and electrochemical displays. In the present work, the films of 50PVA-50PVP blend with different MWt% concentrations of NH4NO3 have been prepared by solution casting techniques using distilled water as a solvent. The prepared films have been investigated by different techniques such as XRD, DSC, Laser Raman and AC Impedance spectroscopy. XRD studies reveal the amorphous nature of the polymer blend-salt complexes. The glass transition temperature has been calculated from the DSC analysis. From the AC Impedance spectroscopy, the high conductivity of the 30MWt% of NH4NO3 doped 50PVA-50PVP polymer complex has been found to be the order of 1.41 × 10-3S cm-1 at room temperature.

  4. Structural (XRD) and thermal (DSC, TGA) and BET analysis of materials derived from non-metal cation pentaborate salts.

    PubMed

    Beckett, Michael A; Horton, Peter N; Hursthouse, Michael B; Knox, David A; Timmis, James L

    2010-04-28

    The synthesis, structural characterization (XRD), and thermal properties of nine non-metal cation (NMC) pentaborate anion salts, [NMC][B(5)O(6)(OH)(4)] (1a-1i) is described (NMC = [NH(3)CMe(2)(CH(2)OH)](+) (a), [O(CH(2)CH(2))(2)NH(2)](+) (b), [NH(3)CMe(CH(2)OH)(2)](+) (c), [2-(2-CH(2)CH(2)OH)PyH](+) (d), [(CH(2))(4)NH(CH(2)CH(2)OH)](+) (e), [(CH(2))(5)NH(CH(2)CH(2)OH)](+) (f), [2-MeImid](+) (g), [Me(3)NCMe(2)(CH(2)OH)](+) (h), [O(CH(2)CH(2))(2)NMe(2)](+) (i). Single-crystal X-ray diffraction studies on all compounds show that they contain isolated pentaborate anions, H-bonded together in a supramolecular array, with the cations occupying the cavities within the network. Compound 1c was obtained as a partial hydrate (0.16H(2)O). TGA and DSC analysis (in air, 25-1000 degrees C) indicate that compounds 1a-1i thermally decompose via a 2 stage process to B(2)O(3). The first stage (<250 degrees C) is dehydration to condensed polymeric pentaborates {approximate composition: [NMC][B(5)O(8)] (2a-2i)}. Five condensed pentaborates (2a-c, 2e, 2g) were synthesised and characterized by powder XRD and BET analysis. These condensed pentaborates were amorphous. The isolated pentaborates intumesced at approximately 600 degrees C (occupying approximately 10 times their original volume), and then contracted back to black glassy B(2)O(3) solids at 1000 degrees C. The intumescent materials (3a), (3b), (3e), (3g), and a final B(2)O(3) sample (4b) were synthesised and isolated and their porosities determined. BET surface area analysis on the isolated pentaborates (1a-c, 1e, 1g), the condensed pentaborates (2a-c, 2e, 2g), intumesced materials (3a, 3b, 3e, 3g), and B(2)O(3) (4b) showed that they were all 'non-porous' (<1.59 m(2) g(-1)).

  5. Optimization of DSC MRI Echo Times for CBV Measurements Using Error Analysis in a Pilot Study of High-Grade Gliomas.

    PubMed

    Bell, L C; Does, M D; Stokes, A M; Baxter, L C; Schmainda, K M; Dueck, A C; Quarles, C C

    2017-09-01

    The optimal TE must be calculated to minimize the variance in CBV measurements made with DSC MR imaging. Simulations can be used to determine the influence of the TE on CBV, but they may not adequately recapitulate the in vivo heterogeneity of precontrast T2*, contrast agent kinetics, and the biophysical basis of contrast agent-induced T2* changes. The purpose of this study was to combine quantitative multiecho DSC MRI T2* time curves with error analysis in order to compute the optimal TE for a traditional single-echo acquisition. Eleven subjects with high-grade gliomas were scanned at 3T with a dual-echo DSC MR imaging sequence to quantify contrast agent-induced T2* changes in this retrospective study. Optimized TEs were calculated with propagation of error analysis for high-grade glial tumors, normal-appearing white matter, and arterial input function estimation. The optimal TE is a weighted average of the T2* values that occur as a contrast agent bolus transverses a voxel. The mean optimal TEs were 30.0 ± 7.4 ms for high-grade glial tumors, 36.3 ± 4.6 ms for normal-appearing white matter, and 11.8 ± 1.4 ms for arterial input function estimation (repeated-measures ANOVA, P < .001). Greater heterogeneity was observed in the optimal TE values for high-grade gliomas, and mean values of all 3 ROIs were statistically significant. The optimal TE for the arterial input function estimation is much shorter; this finding implies that quantitative DSC MR imaging acquisitions would benefit from multiecho acquisitions. In the case of a single-echo acquisition, the optimal TE prescribed should be 30-35 ms (without a preload) and 20-30 ms (with a standard full-dose preload). © 2017 by American Journal of Neuroradiology.

  6. The Utilization of HOPG based Graphene for a less costly and efficient replacement of platinum in Dye-Sensitized Solar Cells (DSC's)

    NASA Astrophysics Data System (ADS)

    Pusko, Matthew P.

    2012-10-01

    Dye-Sensitized Solar Cells (DSC) are also known as Graetzel cells after their inventor, Michael Graetzel, who invented them in 1991. DSCs are potential alternatives to the more conventional and expensive semiconductor p-n junction solar cells like silicon solar cells. In a Graetzel cell, light is absorbed by a sensitizing dye which is coupled to a wide band gap semiconductor (TiO2). Electric charges are liberated by the photon induced electron injection from the dye molecules into the conduction band of the semiconductor. The use of sensitizers in conjunction with the semiconductor oxide permits the absorption of a large portion of the terrestrial solar spectrum with near 10% conversion efficiency. In the ``traditional'' DSC, platinum metal is used as one of the counter electrode materials. In our research, graphene of various forms (from HOPG in specific) is utilized instead of costly platinum to replace the counter-electrode in the DSC's. HOPG also known as Higly Oriented Pyrolitic Graphite is being used to dry deposit graphene layers onto glass or FTO.

  7. Discolored1 (DSC1) is an ADP-Ribosylation Factor-GTPase Activating Protein Required to Maintain Differentiation of Maize Kernel Structures

    PubMed Central

    Takacs, Elizabeth M.; Suzuki, Masaharu; Scanlon, Michael J.

    2012-01-01

    The embryo and endosperm are the products of double fertilization and comprise the clonally distinct products of angiosperm seed development. Recessive mutations in the maize gene discolored1 (dsc1) condition inviable seed that are defective in both embryo and endosperm development. Here, detailed phenotypic analyses illustrate that discolored mutant kernels are able to establish, but fail to maintain, differentiated embryo, and endosperm structures. Development of the discolored mutant embryo and endosperm is normal albeit delayed, prior to the abortion and subsequent degeneration of all differentiated kernel structures. Using a genomic fragment that was previously isolated by transposon tagging, the full length dsc1 transcript is identified and shown to encode an ADP-ribosylation factor-GTPase activating protein (ARF-GAP) that co-localizes with the trans-Golgi network/early endosomes and the plasma membrane during transient expression assays in N. benthamiana leaves. DSC1 function during endomembrane trafficking and the maintenance of maize kernel differentiation is discussed. PMID:22666226

  8. DSC studies to evaluate the impact of bio-oil on cold flow properties and oxidation stability of bio-diesel.

    PubMed

    Garcia-Perez, Manuel; Adams, Thomas T; Goodrum, John W; Das, K C; Geller, Daniel P

    2010-08-01

    This paper describes the use of Differential Scanning Calorimetry (DSC) to evaluate the impact of varying mix ratios of bio-oil (pyrolysis oil) and bio-diesel on the oxidation stability and on some cold flow properties of resulting blends. The bio-oils employed were produced from the semi-continuous Auger pyrolysis of pine pellets and the batch pyrolysis of pine chips. The bio-diesel studied was obtained from poultry fat. The conditions used to prepare the bio-oil/bio-diesel blends as well as some of the fuel properties of these blends are reported. The experimental results suggest that the addition of bio-oil improves the oxidation stability of the resulting blends and modifies the crystallization behavior of unsaturated compounds. Upon the addition of bio-oil an increase in the oxidation onset temperature, as determined by DSC, was observed. The increase in bio-diesel oxidation stability is likely to be due to the presence of hindered phenols abundant in bio-oils. A relatively small reduction in DSC characteristic temperatures which are associated with cold flow properties was also observed but can likely be explained by a dilution effect.

  9. Probing lipid-cholesterol interactions in DOPC/eSM/Chol and DOPC/DPPC/Chol model lipid rafts with DSC and (13)C solid-state NMR.

    PubMed

    Fritzsching, Keith J; Kim, Jihyun; Holland, Gregory P

    2013-08-01

    The interaction between cholesterol (Chol) and phospholipids in bilayers was investigated for the ternary model lipid rafts, DOPC/eSM/Chol and DOPC/DPPC/Chol, with differential scanning calorimetry (DSC) and (13)C cross polarization magic angle spinning (CP-MAS) solid-state NMR. The enthalpy and transition temperature (Tm) of the Lα liquid crystalline phase transition from DSC was used to probe the thermodynamics of the different lipids in the two systems as a function of Chol content. The main chain (13)C (CH2)n resonance is resolved in the (13)C CP-MAS NMR spectra for the unsaturated (DOPC) and saturated (eSM or DPPC) chain lipid in the ternary lipid raft mixtures. The (13)C chemical shift of this resonance can be used to detect differences in chain ordering and overall interactions with Chol for the different lipid constituents in the ternary systems. The combination of DSC and (13)C CP-MAS NMR results indicate that there is a preferential interaction between SM and Chol below Tm for the DOPC/eSM/Chol system when the Chol content is ≤20mol%. In contrast, no preferential interaction between Chol and DPPC is observed in the DOPC/DPPC/Chol system above or below Tm. Finally, (13)C CP-MAS NMR resolves two Chol environments in the DOPC/eSM/Chol system below Tm at Chol contents >20mol% while, a single Chol environment is observed for DOPC/DPPC/Chol at all compositions.

  10. Monitoring of Pentoxifylline Thermal Behavior by Novel Simultaneous Laboratory Small and Wide X-Ray Scattering (SWAXS) and Differential Scanning Calorimetry (DSC).

    PubMed

    Hodzic, Aden; Kriechbaum, Manfred; Schrank, Simone; Reiter, Franz

    2016-01-01

    The thermal and structural evolutions associated to active pharmaceutical ingredient (API) purity are monitored using a laboratory instrument (S3-MicroCaliX) allowing simultaneous time-resolved X-ray scattering at both wide and small angles (SWAXS) as a function of temperature. This is performed simultaneously with differential scanning calorimetric (DSC) that is carried out in the same apparatus at scanning rate of 2 K/min on the same sample in the range from 20° to 200°C. We have studied simultaneous thermal and structural properties of pentoxifylline, as an active pharmaceutical ingredient (API), for its purity quality control. We have found a satisfying API purity, due to obtained melting temperature and enthalpy values, which are in a well agreement with literature. We have also found that the combination of these techniques allows the thermal monitoring of scanning rates of 2 K/min, continuously without the need for static thermal equilibration, particularly for X-ray spectra. Hence, DSC and SWAXS allowing better identification of the structural thermal events recorded by following of the phase transitions simultaneously. This interpretation is much better possible when X-ray scattering at small and wide angles is coupled with DSC from the same sample. Hence, as a laboratory tool, the method presents a reproducible thermal and crystallographic API purity quality control of non-complex samples, as crucial information for pharmaceutical technology.

  11. An evaluation tool for FKBP12-dependent and -independent mTOR inhibitors using a combination of FKBP-mTOR fusion protein, DSC and NMR.

    PubMed

    Sekiguchi, Mitsuhiro; Kobashigawa, Yoshihiro; Kawasaki, Masashi; Yokochi, Masashi; Kiso, Tetsuo; Suzumura, Ken-ichi; Mori, Keitaro; Teramura, Toshio; Inagaki, Fuyuhiko

    2011-11-01

    Mammalian target of rapamycin (mTOR), a large multidomain protein kinase, regulates cell growth and metabolism in response to environmental signals. The FKBP rapamycin-binding (FRB) domain of mTOR is a validated therapeutic target for the development of immunosuppressant and anticancer drugs but is labile and insoluble. Here we designed a fusion protein between FKBP12 and the FRB domain of mTOR. The fusion protein was successfully expressed in Escherichia coli as a soluble form, and was purified by a simple two-step chromatographic procedure. The fusion protein exhibited increased solubility and stability compared with the isolated FRB domain, and facilitated the analysis of rapamycin and FK506 binding using differential scanning calorimetry (DSC) and solution nuclear magnetic resonance (NMR). DSC enabled the rapid observation of protein-drug interactions at the domain level, while NMR gave insights into the protein-drug interactions at the residue level. The use of the FKBP12-FRB fusion protein combined with DSC and NMR provides a useful tool for the efficient screening of FKBP12-dependent as well as -independent inhibitors of the mTOR FRB domain.

  12. Multivariate analysis of DSC-XRD simultaneous measurement data: a study of multistage crystalline structure changes in a linear poly(ethylene imine) thin film.

    PubMed

    Kakuda, Hiroyuki; Okada, Tetsuo; Otsuka, Makoto; Katsumoto, Yukiteru; Hasegawa, Takeshi

    2009-01-01

    A multivariate analytical technique has been applied to the analysis of simultaneous measurement data from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) in order to study thermal changes in crystalline structure of a linear poly(ethylene imine) (LPEI) film. A large number of XRD patterns generated from the simultaneous measurements were subjected to an augmented alternative least-squares (ALS) regression analysis, and the XRD patterns were readily decomposed into chemically independent XRD patterns and their thermal profiles were also obtained at the same time. The decomposed XRD patterns and the profiles were useful in discussing the minute peaks in the DSC. The analytical results revealed the following changes of polymorphisms in detail: An LPEI film prepared by casting an aqueous solution was composed of sesquihydrate and hemihydrate crystals. The sesquihydrate one was lost at an early stage of heating, and the film changed into an amorphous state. Once the sesquihydrate was lost by heating, it was not recovered even when it was cooled back to room temperature. When the sample was heated again, structural changes were found between the hemihydrate and the amorphous components. In this manner, the simultaneous DSC-XRD measurements combined with ALS analysis proved to be powerful for obtaining a better understanding of the thermally induced changes of the crystalline structure in a polymer film.

  13. Investigation of Phase Mixing in Amorphous Solid Dispersions of AMG 517 in HPMC-AS Using DSC, Solid-State NMR, and Solution Calorimetry.

    PubMed

    Calahan, Julie L; Azali, Stephanie C; Munson, Eric J; Nagapudi, Karthik

    2015-11-02

    Intimate phase mixing between the drug and the polymer is considered a prerequisite to achieve good physical stability for amorphous solid dispersions. In this article, spray dried amorphous dispersions (ASDs) of AMG 517 and HPMC-as were studied by differential scanning calorimetry (DSC), solid-state NMR (SSNMR), and solution calorimetry. DSC analysis showed a weakly asymmetric (ΔTg ≈ 13.5) system with a single glass transition for blends of different compositions indicating phase mixing. The Tg-composition data was modeled using the BKCV equation to accommodate the observed negative deviation from ideality. Proton spin-lattice relaxation times in the laboratory and rotating frames ((1)H T1 and T1ρ), as measured by SSNMR, were consistent with the observation that the components of the dispersion were in intimate contact over a 10-20 nm length scale. Based on the heat of mixing calculated from solution calorimetry and the entropy of mixing calculated from the Flory-Huggins theory, the free energy of mixing was calculated. The free energy of mixing was found to be positive for all ASDs, indicating that the drug and polymer are thermodynamically predisposed to phase separation at 25 °C. This suggests that miscibility measured by DSC and SSNMR is achieved kinetically as the result of intimate mixing between drug and polymer during the spray drying process. This kinetic phase mixing is responsible for the physical stability of the ASD.

  14. Determination of the thermo-mechanical properties in starch and starch/gluten systems at low moisture content - a comparison of DSC and TMA.

    PubMed

    Homer, Stephen; Kelly, Michael; Day, Li

    2014-08-08

    The impact of heating rate on the glass transition (Tg) and melting transitions observed by differential scanning calorimetry (DSC) on starch and a starch/gluten blend (80:20 ratio) at low moisture content was examined. The results were compared to those determined by thermo-mechanical analysis (TMA). Comparison with dynamic mechanical thermal analysis (DMTA) and phase transition analysis (PTA) is also discussed. Higher heating rates increased the determined Tg as well as the melting peak temperatures in both starch and the starch/gluten blend. A heating rate of 5°C/min gave the most precise value of Tg while still being clearly observed above the baseline. Tg values determined from the first and second DSC scans were found to differ significantly and retrogradation of starch biopolymers may be responsible. Tg values of starch determined by TMA showed good agreement with DSC results where the Tg was below 80°C. However, moisture loss led to inaccurate Tg determination for TMA analyses at temperatures above 80°C. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Differential Scanning Calorimetry (DSC) and Thermodynamic Prediction of Liquid Fraction vs Temperature for Two High-Performance Alloys for Semi-Solid Processing (Al-Si-Cu-Mg (319s) and Al-Cu-Ag (201))

    NASA Astrophysics Data System (ADS)

    Zhang, Duyao; Atkinson, Helen V.; Dong, Hongbiao; Zhu, Qiang

    2017-10-01

    There is a need to extend the application of semi-solid processing (SSP) to higher performance alloys such as 319s (Al-Si-Cu-Mg) and 201 (Al-Cu-Ag). The melting of these two alloys was investigated using differential scanning calorimetry (DSC) and thermodynamic prediction. The alloys had been processed by magneto-hydrodynamic (MHD) stirring before receipt to produce a microstructure suitable for SSP. The DSC results for the as-received MHD material were compared with those for material which has been taken through a complete DSC cycle and then reheated for a second DSC run. The effects of microsegregation were then analyzed. A higher liquid fraction for a particular temperature is found in the second DSC run than the first. Microstructural observations suggest this is because the intermetallics which form during the first cooling cycle tend to co-located. Quaternary and ternary reactions then occur during the second DSC heat and the co-location leads to enhanced peaks. The calculated liquid fraction is lower with 10 K/min DSC heating rate comparing with 3 K/min at a given temperature. The DSC scan rate must therefore be carefully considered if it is to be used to identify temperature parameters or the suitability of alloys for SSP. In addition, the starting material for DSC must represent the starting material for the SSP. With thermodynamic prediction, the equilibrium condition will provide better guidance for the thixoforming of MHD stirred starting material than the Scheil condition. The Scheil mode approximates more closely with a strongly microsegregated state.

  16. A Serious Game for Massive Training and Assessment of French Soldiers Involved in Forward Combat Casualty Care (3D-SC1): Development and Deployment

    PubMed Central

    Mérat, Stéphane; Malgras, Brice; Petit, Ludovic; Queran, Xavier; Bay, Christian; Boutonnet, Mathieu; Jault, Patrick; Ausset, Sylvain; Auroy, Yves; Perez, Jean Paul; Tesnière, Antoine; Pons, François; Mignon, Alexandre

    2016-01-01

    Background The French Military Health Service has standardized its military prehospital care policy in a ‘‘Sauvetage au Combat’’ (SC) program (Forward Combat Casualty Care). A major part of the SC training program relies on simulations, which are challenging and costly when dealing with more than 80,000 soldiers. In 2014, the French Military Health Service decided to develop and deploy 3D-SC1, a serious game (SG) intended to train and assess soldiers managing the early steps of SC. Objectives The purpose of this paper is to describe the creation and production of 3D-SC1 and to present its deployment. Methods A group of 10 experts and the Paris Descartes University Medical Simulation Department spin-off, Medusims, coproduced 3D-SC1. Medusims are virtual medical experiences using 3D real-time videogame technology (creation of an environment and avatars in different scenarios) designed for educational purposes (training and assessment) to simulate medical situations. These virtual situations have been created based on real cases and tested on mannequins by experts. Trainees are asked to manage specific situations according to best practices recommended by SC, and receive a score and a personalized feedback regarding their performance. Results The scenario simulated in the SG is an attack on a patrol of 3 soldiers with an improvised explosive device explosion as a result of which one soldier dies, one soldier is slightly stunned, and the third soldier experiences a leg amputation and other injuries. This scenario was first tested with mannequins in military simulation centers, before being transformed into a virtual 3D real-time scenario using a multi-support, multi–operating system platform, Unity. Processes of gamification and scoring were applied, with 2 levels of difficulty. A personalized debriefing was integrated at the end of the simulations. The design and production of the SG took 9 months. The deployment, performed in 3 months, has reached 84 of 96

  17. A Serious Game for Massive Training and Assessment of French Soldiers Involved in Forward Combat Casualty Care (3D-SC1): Development and Deployment.

    PubMed

    Pasquier, Pierre; Mérat, Stéphane; Malgras, Brice; Petit, Ludovic; Queran, Xavier; Bay, Christian; Boutonnet, Mathieu; Jault, Patrick; Ausset, Sylvain; Auroy, Yves; Perez, Jean Paul; Tesnière, Antoine; Pons, François; Mignon, Alexandre

    2016-05-18

    The French Military Health Service has standardized its military prehospital care policy in a ''Sauvetage au Combat'' (SC) program (Forward Combat Casualty Care). A major part of the SC training program relies on simulations, which are challenging and costly when dealing with more than 80,000 soldiers. In 2014, the French Military Health Service decided to develop and deploy 3D-SC1, a serious game (SG) intended to train and assess soldiers managing the early steps of SC. The purpose of this paper is to describe the creation and production of 3D-SC1 and to present its deployment. A group of 10 experts and the Paris Descartes University Medical Simulation Department spin-off, Medusims, coproduced 3D-SC1. Medusims are virtual medical experiences using 3D real-time videogame technology (creation of an environment and avatars in different scenarios) designed for educational purposes (training and assessment) to simulate medical situations. These virtual situations have been created based on real cases and tested on mannequins by experts. Trainees are asked to manage specific situations according to best practices recommended by SC, and receive a score and a personalized feedback regarding their performance. The scenario simulated in the SG is an attack on a patrol of 3 soldiers with an improvised explosive device explosion as a result of which one soldier dies, one soldier is slightly stunned, and the third soldier experiences a leg amputation and other injuries. This scenario was first tested with mannequins in military simulation centers, before being transformed into a virtual 3D real-time scenario using a multi-support, multi-operating system platform, Unity. Processes of gamification and scoring were applied, with 2 levels of difficulty. A personalized debriefing was integrated at the end of the simulations. The design and production of the SG took 9 months. The deployment, performed in 3 months, has reached 84 of 96 (88%) French Army units, with a total of 818

  18. Use of DSC and DMA to Study Rubber Crystallization as a Possible Cause for a Tear in a Neoprene Glove Used in a Space Shuttle Pressurized Astronaut Suit

    NASA Technical Reports Server (NTRS)

    Wingard, Doug

    2009-01-01

    The Advanced Crew Escape Suit (ACES) is a pressurized suit normally worn by astronauts during launch and landing phases of Space Shuttle operations. In 2008, a large tear (0.5 -1 in. long, between the pinky and ring finger) in the ACES left-hand glove made of neoprene latex rubber was found during training for Shuttle flight STS-124. An investigation to help determine the cause(s) of the glove tear was headed by the NASA Johnson Space Center (JSC) in Houston, Texas. Efforts at JSC to reproduce the actual glove tear pattern by cutting/tearing or rupturing were unsuccessful. Chemical and material property data from JSC such as GC-MS, FTIR, DSC and TGA mostly showed little differences between samples from the torn and control gloves. One possible cause for the glove tear could be a wedding ring/band worn by a male astronaut. Even with a smooth edge, such a ring could scratch the material and initiate the tear observed in the left-hand glove. A decision was later made by JSC to not allow the wearing of such a ring during training or actual flight. Another possible cause for the ACES glove tear is crystallinity induced by strain in the neoprene rubber over a long period of time and use. Neoprene is one several elastomeric materials known to be susceptible to crystallization, and such a process is accelerated with exposure of the material to cold temperatures plus strain. When the temperature is lowered below room temperature, researchers have shown that neoprene crystallization may be maintained at temperatures as high as 45-50 F, with a maximum crystallization rate near 20-25 F (1). A convenient conditioning temperature for inducing neoprene crystallization is a typical freezer that is held near 0 F. For work at the NASA Marshall Space Flight Center (MSFC), samples were cut from several areas/locations (pinky/ring finger crotch, index finger and palm) on each of two pairs of unstrained ACES gloves for DSC and DMA thermal analysis testing. The samples were conditioned

  19. Analysis of DSC thermal curves for assigning a characteristic glass transition temperature, dependent on either the type or thermal history of the polymer

    SciTech Connect

    Saffell, J.R.

    1994-09-01

    DSC was used to study the thermal curve characteristics of four classical polymer glasses: polycarbonate (PC), anionic polystyrene (aPS), polysulfone, and polymethyl methacrylate (PMMA). The onset, peak, and fictive temperatures as well as endotherm characteristics were studied over two decades of heating and cooling rates. Assuming that the fictive temperature is independent of heating rate, the usefulness of T{sub onset} and ambiguity of T{sub peak} are demonstrated. The useful [heat/cool] ratio allows use of T{sub onset} to calculate the effective cooling rate of the sample (which is easier to calculate than T{sub fictive}). Comparison with results from annealed samples are shown. The fictive and onset temperatures can be used together to improve the reliability of glass temperature characterization and results are surprisingly constant between the four different types of glasses, leading to a method of providing a single temperature to characterize the thermal history/morphology using a DSC thermal curve. The peak temperature is nearly independent of thermal history, and so provides a characterization parameter that is insensitive to manufacturing and molding procedures.

  20. DSC, X-ray and FTIR studies of a gemfibrozil/dimethyl-β-cyclodextrin inclusion complex produced by co-grinding.

    PubMed

    Aigner, Z; Berkesi, O; Farkas, G; Szabó-Révész, P

    2012-01-05

    The steps of formation of an inclusion complex produced by the co-grinding of gemfibrozil and dimethyl-β-cyclodextrin were investigated by differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD) and Fourier transform infrared (FTIR) spectroscopy with curve-fitting analysis. The endothermic peak at 59.25°C reflecting the melting of gemfibrozil progressively disappeared from the DSC curves of the products on increase of the duration of co-grinding. The crystallinity of the samples too gradually decreased, and after 35min of co-grinding the product was totally amorphous. Up to this co-grinding time, XRPD and FTIR investigations indicated a linear correlation between the cyclodextrin complexation and the co-grinding time. After co-grinding for 30min, the ratio of complex formation did not increase. These studies demonstrated that co-grinding is a suitable method for the complexation of gemfibrozil with dimethyl-β-cyclodextrin. XRPD analysis revealed the amorphous state of the gemfibrozil-dimethyl-β-cyclodextrin product. FTIR spectroscopy with curve-fitting analysis may be useful as a semiquantitative analytical method for discriminating the molecular and amorphous states of gemfibrozil.

  1. Assessment of bevacizumab resistance increased by expression of BCAT1 in IDH1 wild-type glioblastoma: application of DSC perfusion MR imaging

    PubMed Central

    Cho, Hye Rim; Hong, Bora; Kim, Hyeonjin; Park, Chul-Kee; Park, Sung-Hye; Park, Sunghyouk; Choi, Seung Hong

    2016-01-01

    BCAT1 (branched-chain amino acid trasaminase1) expression is necessary for the progression of IDH1 wild-type (WT) glioblastoma multiforme (GBM), which is known to be associated with aggressive tumors. The purpose of our study is to investigate the bevacizumab resistance increased by the expression of BCAT1 in IDH1 WT GBM in a rat model, which was evaluated using DSC perfusion MRI. BCAT1 sh#1 inhibits cell proliferation and limits cell migration potential in vitro. In vivo MRI showed that the increase in both tumor volume and nCBV after bevacizumab treatment in IDH1 WT tumors was significantly higher compared with BCAT1 sh#1tumors. In a histological analysis, more micro-vessel reformation by bevacizumab resistance was observed in IDH1 WT tumors than BCAT1 sh#1 tumors. These findings indicate that BCAT1 expression in IDH1 WT GBM increases resistance to bevacizumab treatment, which could be assessed by DSC perfusion MRI, and that nCBV can be a surrogate imaging biomarker for the prediction of antiangiogenic treatment in GBM. PMID:27626306

  2. Assessment of bevacizumab resistance increased by expression of BCAT1 in IDH1 wild-type glioblastoma: application of DSC perfusion MR imaging.

    PubMed

    Cho, Hye Rim; Hong, Bora; Kim, Hyeonjin; Park, Chul-Kee; Park, Sung-Hye; Park, Sunghyouk; Choi, Seung Hong

    2016-10-25

    BCAT1 (branched-chain amino acid trasaminase1) expression is necessary for the progression of IDH1 wild-type (WT) glioblastoma multiforme (GBM), which is known to be associated with aggressive tumors. The purpose of our study is to investigate the bevacizumab resistance increased by the expression of BCAT1 in IDH1 WT GBM in a rat model, which was evaluated using DSC perfusion MRI. BCAT1 sh#1 inhibits cell proliferation and limits cell migration potential in vitro. In vivo MRI showed that the increase in both tumor volume and nCBV after bevacizumab treatment in IDH1 WT tumors was significantly higher compared with BCAT1 sh#1tumors. In a histological analysis, more micro-vessel reformation by bevacizumab resistance was observed in IDH1 WT tumors than BCAT1 sh#1 tumors. These findings indicate that BCAT1 expression in IDH1 WT GBM increases resistance to bevacizumab treatment, which could be assessed by DSC perfusion MRI, and that nCBV can be a surrogate imaging biomarker for the prediction of antiangiogenic treatment in GBM.

  3. Kinetics of Cold-Cap Reactions for Vitrification of Nuclear Waste Glass Based on Simultaneous Differential Scanning Calorimetry - Thermogravimetry (DSC-TGA) and Evolved Gas Analysis (EGA)

    SciTech Connect

    Rodriguez, Carmen P.; Pierce, David A.; Schweiger, Michael J.; Kruger, Albert A.; Chun, Jaehun; Hrma, Pavel R.

    2013-12-03

    For vitrifying nuclear waste glass, the feed, a mixture of waste with glass-forming and modifying additives, is charged onto the cold cap that covers 90-100% of the melt surface. The cold cap consists of a layer of reacting molten glass floating on the surface of the melt in an all-electric, continuous glass melter. As the feed moves through the cold cap, it undergoes chemical reactions and phase transitions through which it is converted to molten glass that moves from the cold cap into the melt pool. The process involves a series of reactions that generate multiple gases and subsequent mass loss and foaming significantly influence the mass and heat transfers. The rate of glass melting, which is greatly influenced by mass and heat transfers, affects the vitrification process and the efficiency of the immobilization of nuclear waste. We studied the cold-cap reactions of a representative waste glass feed using both the simultaneous differential scanning calorimetry thermogravimetry (DSC-TGA) and the thermogravimetry coupled with gas chromatography-mass spectrometer (TGA-GC-MS) as complementary tools to perform evolved gas analysis (EGA). Analyses from DSC-TGA and EGA on the cold-cap reactions provide a key element for the development of an advanced cold-cap model. It also helps to formulate melter feeds for higher production rate.

  4. Lyotropic model membrane structures of hydrated DPPC: DSC and small-angle X-ray scattering studies of phase transitions in the presence of membranotropic agents

    NASA Astrophysics Data System (ADS)

    Bulavin, L. A.; Soloviov, D. V.; Gordeliy, V. I.; Svechnikova, O. S.; Krasnikova, A. O.; Kasian, N. A.; Vashchenko, O. V.; Lisetski, L. N.

    2015-06-01

    Multibilayer structures of hydrated phospholipids, often considered as model biological membranes, are, from the physical viewpoint, lyotropic liquid crystalline systems undergoing temperature-induced mesomorphic phase transitions. Effects of silver nitrate and urocanic acid on lyotropic phase states of hydrated L-α-dipalmitoylphosphatidylcholine (DPPC) have been studied by small-angle X-ray scattering and differential scanning calorimetry (DSC). Both methods show increase of the main phase-transition temperature (Tm) of hydrated DPPC upon introduction of AgNO3 or urocanic acid, decrease of pre-transition temperature (Tp) in the presence of urocanic acid and its increase in the presence of AgNO3. Thus, urocanic acid widened the ripple-phase temperature region. Silver nitrate caused the appearance of an additional high-temperature peak on DSC thermograms, evidencing phase separation in the system. Both agents caused minor effects on DPPC lipid bilayer repeat distance (D) in gel phase, but resulted in noticeable increase of D in the liquid crystal phase with temperature as compared to undoped DPPC structures.

  5. An experimental study of the (Ti-6Al-4V)-xH phase diagram using in situ synchrotron XRD and TGA/DSC techniques.

    SciTech Connect

    Sun, Pei; Fang, Z. Zak; Koopman, Mark; Paramore, James D.; Chandran, K. S. Ravi; Ren, Yang; Lu, Jun

    2015-02-01

    Hydrogen has been investigated for decades as a temporary alloying element to refine the microstructure of Ti-6Al-4V, and is now being used in a novel powder metallurgy method known as "hydrogen sintering and phase transformation". Pseudo-binary phase diagrams of (Ti-6Al-4V)-xH have been studied and developed, but are not well established due to methodological limitations. In this paper, in situ studies of phase transformations during hydrogenation and dehydrogenation of (Ti-6Al-4V)-xH alloys were conducted using high-energy synchrotron X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The eutectoid phase transformation of β ↔ α + δ was observed in the (Ti-6Al-4V)-xH alloy via in situ synchrotron XRD at 211 °C with a hydrogen concentration of 37.5 at.% (measured using TGA-DSC). The relationships of hydrogen composition to partial pressure and temperature were investigated in the temperature range 450-900°C. Based on these results, a partial pseudo-binary phase diagram of (Ti-6Al-4V)-xH is proposed for hydrogen compositions up to 60 at.% in the temperature range 100-900°C. Using the data collected in real time under controlled parameters of temperature, composition and hydrogen partial pressure, this work characterizes relevant phase transformations and microstructural evolution for practical titanium-hydrogen technologies of Ti-6Al-4V.

  6. Preliminary Analysis of the Social and Scientific Impact of the UAEM-ININ M.Sc. and D.Sc. Graduate Programme in Medical Physics

    NASA Astrophysics Data System (ADS)

    Mitsoura, Eleni; Isaac-Olive, Keila; Torres-Garcia, Eugenio; Camacho-Lopez, Miguel Angel; Hardy-Perez, Alberto

    2010-12-01

    Sponsored by the International Atomic Energy Agency (IAEA) in 1994, the Instituto Nacional de Investigaciones Nucleares (ININ) started in Mexico a teaching and training programme (Diplomado) in Radiotherapy Medical Physics. Based on this experience, the Universidad Autónoma del Estado de México (UAEM) and the Instituto Nacional de Investigaciones Nucleares (ININ) launched two years later, the first Graduate Programme in Science (M.Sc. and D.Sc.), specialised in Medical Physics in Mexico. A preliminary analysis of the social and scientific impact of the UAEM-ININ Programme is presented in this work based on the achievements attained, regarding the number of graduated Medical Physicists, their geographic and academic origin, their current professional activities and the number of scientific publications produced as a result of the thesis, as well as their citations.

  7. A thermoreversible double gel: characterization of a methylcellulose and kappa-carrageenan mixed system in water by SAXS, DSC and rheology.

    PubMed

    Tomsic, Matija; Prossnigg, Florian; Glatter, Otto

    2008-06-01

    Sol-gel and gel-sol thermal transition of methylcellulose/water, kappa-carrageenan/water and methylcellulose/kappa-carrageenan/water mixtures was investigated utilizing small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) and oscillatory rheological experiments in temperature regime from 20 to 80 degrees C. Methylcellulose (E461) and kappa-carrageenan (E407) are well-known additives used for gelation in various nutrition and other products. The formulation and characterization of a mixed thermoreversible methylcellulose/kappa-carrageenan/water gel with very interesting double thermal transition gel-sol-gel upon heating was possible. This specific thermal behavior provides a liquid state of the system between the low-temperature and high-temperature gel-state and at the same time allows for the easy temperature tuning of the system's state. As such this system is suggested to be further tested as potential carrier for various functional colloidal systems.

  8. Study of the Crystalline Morphology Evolution of PET and PET/PC Blends by Time-resolved Synchrotron Small Angle X-ray Scattering (SAXS) and DSC

    SciTech Connect

    Barbosa, Irineu; Larocca, Nelson M.; Hage, Elias; Plivelic, Tomas S.; Torriani, Iris L.; Mantovani, Gerson L.

    2009-01-29

    Isothermal melt crystallization of poly(ethylene terephthalate)(PET) and PET/PC (polycarbonate) blend, with and without a transesterification catalyst, was studied by time-resolved small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) in order to achieve the variation of the morphological parameters throughout the whole crystallization time. For neat PET, the catalyst promotes a decrease of the crystal lamellar thickness but for the blend no variations were observed. The effect of incorporation of catalyst in crystallization kinetics was very distinct in PET pure and the blend: in the former the catalyst leads to an increase of this kinetics while for the latter it was observed a decreasing.

  9. Identification of thermal effects involved in DSC experiment on Al-Cu-Mg-Ag alloys with high Cu:Mg ratio

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Bo; Zhang, Yong-An; Zhu, Bao-Hong; Wang, Feng; Li, Zhi-Hui; Li, Xi-Wu; Xiong, Bai-Qing

    2011-12-01

    Precipitation reactions in the differential scanning calorimetry (DSC) of an Al-Cu-Mg-Ag alloy were identified by analyzing the results from hardness test, electrical conductivity test, and transmission electron microscope (TEM) examination. It is discovered that thermal effects can be identified through selected area electron diffraction and bright-field images. The reaction peaks around 171, 231, and 276°C can be attributed to a structural rearrangement of coherent zones, to the precipitation of Ω phases, and to the precipitation of Ω and θ' and possible combination with the transition of θ'→θ, respectively. In addition, the hardness and electrical conductivity of the alloy change proportionately with the progression of reactions during the heating process. This phenomenon can be attributed to the evolution of the microstructure.

  10. The Effect of Various Vehicles on the Naproxen Permeability through Rat Skin: A Mechanistic Study by DSC and FT-IR Techniques

    PubMed Central

    Salimi, Anayatollah; Hedayatipour, Najme; Moghimipour, Eskandar

    2016-01-01

    Purpose: The purpose of the present investigation was to evaluate the effectiveness of different vehicles on drug permeability and microstructure of intercellular or lipids in SC layer of skin. Methods: Pre-treated skin of rat using some vehicles including Labarac PG ,Transcutol P, tween 80, span 80 and propylene glycol (PG), were mounted on specialized design franz-diffusion cell was used to assess naproxen permeation and parameters such as permeability coefficients and state flux (Jss) were evaluated. Any differences in peak position and also change in symmetric and asymmetric stretching of C-H bond, lipid ester carbonyl stretching in SC, C=O stretching (Amide I) and C-N stretching of keratin (Amide II) absorbance using Fourier transform infrared spectroscopy (FTIR) were considered to investigate the enhancing mechanism. DSC method was utilized to compare their mean transition temperature (Tm) and enthalpies (ΔH). Results: Steady-state flux (Jss), permeability coefficient (Kp) and diffusion coefficient (D) were significantly (p<0.05) increased by using their span80 showed the biggest enhancement ratio (ERflux) and Transcutol P, Labrafac PG, Tween 80 and Propylene glycol were at the next levels. In comprised to hydrated rat skin the maximum increase in diffusion coefficient was for Tween 80(p<0.05), Lipid fluidization, lipid disruption structure and the irreversible denaturation of proteins in the SC layer of skin by span 80, Tween 80, Labrafac PG, Transcutol P and propylene glycol, were indicated by FT-IR and DSC techniques. Conclusion: It is concluded that naproxen permeation through rat skin may be facilitated by utilizing the vehicle systems. Lipid fluidization and lipid extraction are among suggested mechanisms. PMID:27099831

  11. Simultaneous determination of the protein conversion process in porcine stratum corneum after pretreatment with skin enhancers by a combined microscopic FT-IR/DSC system

    NASA Astrophysics Data System (ADS)

    Lin, Shan-Yang; Duan, Kwo-Jen; Lin, Tsung-Chien

    1996-11-01

    A newly developed microscopic Fourier transform infrared (FT-IR) spectrometry combined with differential scanning calorimetry (DSC) has been used to investigate simultaneously the thermal response and IR spectral changes in protein structure in porcine stratum corneum (SC) after pretreatment with skin penetration enhancers (propylene glycol (PG), azone/PG, oleic acid (OA)/PG, vitamin C, and vitamin C+ OA/PG). The amide I and II bands of the protein were used as probes to determine its structural transformation with temperature. A reheating process was also performed. The dual effects of enhancer and temperature on the protein conformational changes of porcine SC were studied. The results indicate that the newly developed FT-IR/DSC system can continuously determine the thermoresponsive conversion process from α-helix to β-sheet in the keratin structure of porcine SC pretreated with different enhancers. The temperature-induced keratin conversion in the protein structure of porcine SC was irreversible, with or without pretreatment with skin penetration enhancers. The conformational transition in the protein during heating was found to be partially from the α-helix to a random coil structure, and partially from the α-helix to the β-sheet structure. The kinetics of this conversion for the first and second heating processes were significantly different; the conversion process for all the first-heated SC samples during the second heating process was slower than that of the samples during the first heating process. Moreover, it was found that the skin penetration enhancers were able to alter synergistically and promote keratin conversion in the protein structure of porcine SC when accompanying the heating process. PG, OA/PG and azone/PG were found to be the most effective.

  12. Comparative SAXS and DSC study on stratum corneum structural organization in an epidermal cell culture model (ROC): impact of cultivation time.

    PubMed

    Kuntsche, Judith; Herre, Angela; Fahr, Alfred; Funari, Sérgio S; Garidel, Patrick

    2013-12-18

    Cell cultured skin equivalents present an alternative for dermatological in vitro evaluations of drugs and excipients as they provide the advantage of availability, lower variability and higher assay robustness compared to native skin. For penetration/permeation studies, an adequate stratum corneum barrier similar to that of human stratum corneum is, however, a prerequisite. In this study, the stratum corneum lipid organization in an epidermal cell culture model based on rat epidermal keratinocytes (REK organotypic culture, ROC) was investigated by small-angle X-ray scattering (SAXS) in dependence on ROC cultivation time and in comparison to native human and rat stratum cornea. In addition, the thermal phase behavior was studied by differential scanning calorimetry (DSC) and barrier properties were checked by measurements of the permeability of tritiated water. The development of the barrier of ROC SC obtained at different cultivation times (7, 14 and 21 days at the air-liquid interface) was connected with an increase in structural order of the SC lipids in SAXS measurements: Already cultivation for 14 days at the air-liquid interface resulted overall in a competent SC permeability barrier and SC lipid organization. Cultivation for 21 days resulted in further minor changes in the structural organization of ROC SC. The SAXS patterns of ROC SC had overall large similarities with that of human SC and point to the presence of a long periodicity phase with a repeat distance of about 122Å, e.g. slightly smaller than that determined for human SC in the present study (127Å). Moreover, SAXS results also indicate the presence of covalently bound ceramides, which are crucial for a proper SC barrier, although the corresponding thermal transitions were not clearly detectable by DSC. Due to the competent SC barrier properties and high structural and organizational similarity to that of native human SC, ROC presents a promising alternative for in vitro studies, particularly as

  13. Elaboration, structural, spectroscopy, DSC investigations and Hirshfeld surface analysis of a one-dimensional self-assembled organic-inorganic hybrid compound

    NASA Astrophysics Data System (ADS)

    Mesbeh, Radhia; Hamdi, Besma; Zouari, Ridha

    2017-01-01

    The new organic-inorganic hybrid of the formula [H2mela]Cu2Cl6, where mela = 1,3,5-triazine-2,4,6-triamine, has been synthesized by the reaction of 1,3,5-triazine-2,4,6-triamine and copper(II) chloride dihydrate in the presence of hydrochloric acid. This compound has been determined by X-ray diffraction analysis and characterized by FT-IR, Raman, NMR characterization, differential scanning calorimetric (DSC) analysis, dielectric measurements and Hirshfeld surface. 1,3,5-triazinidium-2,4,6-triamine hexachlorodicuprate(II) crystallizes in the monoclinic system with space group P21/c. The final refinement of the structure of the program led to the reliability factors unweighted R1 = 3.53% and weighted WR2 = 8.87%. The observed internal C3sbnd N31sbnd C1 and C3sbnd N23sbnd C2 angle (121.5 and 121.4°) at protanated N-atom are significantly greater the other ring angle C1sbnd N12sbnd C2 (117.1°). The titled compound crystallizes as an organic-inorganic one-dimensional (1D) structure. The crystal structure was stabilized by two types of hydrogen bonding Nsbnd H⋯Cl and Nsbnd H⋯N. The infrared spectra was recorded in the 4000-400 cm-1 frequency region and the Raman spectra was recorded in the external region of the anionic sublattice vibration 4000-50 cm-1 at room temperature. Solid-state 13C and 63Cu MAS-NMR spectroscopies are in agreement with the X-ray structure. The differential scanning calorimetric (DSC) show the presence of a structural phase transition of the title compound at 338 K. Hirshfeld surface analyses for visually analyzing intermolecular interactions in crystal structures employing molecular surface contours and 2D fingerprint plots have been used to examine molecular shapes.

  14. Use of thermal analysis techniques (TG-DSC) for the characterization of diverse organic municipal waste streams to predict biological stability prior to land application

    SciTech Connect

    Fernandez, Jose M.; Plaza, Cesar; Polo, Alfredo; Plante, Alain F.

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Thermal analysis was used to assess stability and composition of organic matter in three diverse municipal waste streams. Black-Right-Pointing-Pointer Results were compared with C mineralization during 90-day incubation, FTIR and {sup 13}C NMR. Black-Right-Pointing-Pointer Thermal analysis reflected the differences between the organic wastes before and after the incubation. Black-Right-Pointing-Pointer The calculated energy density showed a strong correlation with cumulative respiration. Black-Right-Pointing-Pointer Conventional and thermal methods provide complimentary means of characterizing organic wastes. - Abstract: The use of organic municipal wastes as soil amendments is an increasing practice that can divert significant amounts of waste from landfill, and provides a potential source of nutrients and organic matter to ameliorate degraded soils. Due to the high heterogeneity of organic municipal waste streams, it is difficult to rapidly and cost-effectively establish their suitability as soil amendments using a single method. Thermal analysis has been proposed as an evolving technique to assess the stability and composition of the organic matter present in these wastes. In this study, three different organic municipal waste streams (i.e., a municipal waste compost (MC), a composted sewage sludge (CS) and a thermally dried sewage sludge (TS)) were characterized using conventional and thermal methods. The conventional methods used to test organic matter stability included laboratory incubation with measurement of respired C, and spectroscopic methods to characterize chemical composition. Carbon mineralization was measured during a 90-day incubation, and samples before and after incubation were analyzed by chemical (elemental analysis) and spectroscopic (infrared and nuclear magnetic resonance) methods. Results were compared with those obtained by thermogravimetry (TG) and differential scanning calorimetry (DSC

  15. Physicochemical characterization by AFM, FT-IR and DSC and biological assays of a promising antileishmania delivery system loaded with a natural Brazilian product.

    PubMed

    Marquele-Oliveira, Franciane; Torres, Elina Cassia; Barud, Hernane da Silva; Zoccal, Karina Furlani; Faccioli, Lúcia Helena; Hori, Juliana I; Berretta, Andresa Aparecida

    2016-05-10

    The control and treatment of Leishmaniasis, a neglected and infectious disease affecting approximately 12 million people worldwide, are challenging. Leishmania parasites multiply intracellularly within macrophages located in deep skin and in visceral tissues, and the currently employed treatments for this disease are subject to significant drawbacks, such as resistance and toxicity. Thus, the search for new Leishmaniasis treatments is compulsory, and Ocotea duckei Vattimo, a plant-derived product from the biodiverse Brazilian flora, may be a promising new treatment for this disease. In this regard, the aim of this work was to develop and characterize a delivery system based on solid lipid nanoparticles (SLN) that contain the liposoluble lignan fraction (LF) of Ocotea duckei Vattimo, which targets the Leishmania phagolysosome of infected macrophages. LF-loaded SLNs were obtained via the hot microemulsion method, and their physical and chemical properties were comprehensively assessed using PCS, AFM, SEM, FT-IR, DSC, HPLC, kinetic drug release studies, and biological assays. The size of the developed delivery system was 218.85±14.2 nm, its zeta potential was -30 mV and its entrapment efficiency (EE%) was high (the EEs% of YAN [yangambin] and EPI-YAN [epi-yangambin] markers were 94.21±0.40% and 94.20±0.00%, respectively). Microscopy, FT-IR and DSC assays confirmed that the delivery system was nanosized and indicated a core-shell encapsulation model, which corroborated the measured kinetics of drug release. The total in vitro release rates of YAN and EPI-YAN in buffer (with sink conditions attained) were 29.6±8.3% and 34.3±8.9%, respectively, via diffusion through the cellulose acetate membrane of the SLN over a period of 4 h. After 24 h, the release rates of both markers reached approximately 45%, suggesting a sustained pattern of release. Mathematical modeling indicated that both markers, YAN and EPI-YAN, followed matrix diffusion-based release kinetics (Higuchi

  16. Novel organic NLO material bis(N-phenylbiguanidium(1+)) oxalate - A combined X-ray diffraction, DSC and vibrational spectroscopic study of its unique polymorphism

    NASA Astrophysics Data System (ADS)

    Matulková, Irena; Císařová, Ivana; Vaněk, Přemysl; Němec, Petr; Němec, Ivan

    2017-01-01

    Three polymorphic modifications of bis(N-phenylbiguanidium(1+)) oxalate are reported, and their characterization is discussed in this paper. The non-centrosymmetric bis(N-phenylbiguanidium(1+)) oxalate (I), which was obtained from an aqueous solution at 313 K, belongs to the monoclinic space group Cc (a = 6.2560(2) Å, b = 18.6920(3) Å, c = 18.2980(5) Å, β = 96.249(1)°, V = 2127.0(1) Å3, Z = 4, R = 0.0314 for 4738 observed reflections). The centrosymmetric bis(N-phenylbiguanidium(1+)) oxalate (II) was obtained from an aqueous solution at 298 K and belongs to the monoclinic space group P21/n (a = 6.1335(3) Å, b = 11.7862(6) Å, c = 14.5962(8) Å, β = 95.728(2)°, V = 1049.90(9) Å3, Z = 4, R = 0.0420 for 2396 observed reflections). The cooling of the centrosymmetric phase (II) leads to the formation of bis(N-phenylbiguanidium(1+)) oxalate (III) (a = 6.1083(2) Å, b = 11.3178(5) Å, c = 14.9947(5) Å, β = 93.151(2)°, V = 1035.05(8) Å3, Z = 4, R = 0.0345 for 2367 observed reflections and a temperature of 110 K), which also belongs to the monoclinic space group P21/n. The crystal structures of the three characterized phases are generally based on layers of isolated N-phenylbiguanidium(1 +) cations separated by oxalate anions and interconnected with them by several types of N-H...O hydrogen bonds. The observed phases generally differ not only in their crystal packing but also in the lengths and characteristics of their hydrogen bonds. The thermal behaviour of the prepared compounds was studied using the DSC method in the temperature range from 90 K up to a temperature near the melting point of each crystal. The bis(N-phenylbiguanidium(1+)) oxalate (II) crystals exhibit weak reversible thermal effects on the DSC curve at 147 K (heating run). Further investigation of this effect, which was assigned to the isostructural phase transformation, was performed using FTIR, Raman spectroscopy and X-ray diffraction analysis in a wide temperature range.

  17. Novel organic NLO material bis(N-phenylbiguanidium(1+)) oxalate - A combined X-ray diffraction, DSC and vibrational spectroscopic study of its unique polymorphism.

    PubMed

    Matulková, Irena; Císařová, Ivana; Vaněk, Přemysl; Němec, Petr; Němec, Ivan

    2017-01-05

    Three polymorphic modifications of bis(N-phenylbiguanidium(1+)) oxalate are reported, and their characterization is discussed in this paper. The non-centrosymmetric bis(N-phenylbiguanidium(1+)) oxalate (I), which was obtained from an aqueous solution at 313K, belongs to the monoclinic space group Cc (a=6.2560(2)Å, b=18.6920(3)Å, c=18.2980(5)Å, β=96.249(1)°, V=2127.0(1)Å(3), Z=4, R=0.0314 for 4738 observed reflections). The centrosymmetric bis(N-phenylbiguanidium(1+)) oxalate (II) was obtained from an aqueous solution at 298K and belongs to the monoclinic space group P21/n (a=6.1335(3)Å, b=11.7862(6)Å, c=14.5962(8)Å, β=95.728(2)°, V=1049.90(9)Å(3), Z=4, R=0.0420 for 2396 observed reflections). The cooling of the centrosymmetric phase (II) leads to the formation of bis(N-phenylbiguanidium(1+)) oxalate (III) (a=6.1083(2)Å, b=11.3178(5)Å, c=14.9947(5)Å, β=93.151(2)°, V=1035.05(8)Å(3), Z=4, R=0.0345 for 2367 observed reflections and a temperature of 110K), which also belongs to the monoclinic space group P21/n. The crystal structures of the three characterized phases are generally based on layers of isolated N-phenylbiguanidium(1+) cations separated by oxalate anions and interconnected with them by several types of N-H(...)O hydrogen bonds. The observed phases generally differ not only in their crystal packing but also in the lengths and characteristics of their hydrogen bonds. The thermal behaviour of the prepared compounds was studied using the DSC method in the temperature range from 90K up to a temperature near the melting point of each crystal. The bis(N-phenylbiguanidium(1+)) oxalate (II) crystals exhibit weak reversible thermal effects on the DSC curve at 147K (heating run). Further investigation of this effect, which was assigned to the isostructural phase transformation, was performed using FTIR, Raman spectroscopy and X-ray diffraction analysis in a wide temperature range. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. DSC and optical studies on BaO-Li{sub 2}O-B{sub 2}O{sub 3}-CuO glass system

    SciTech Connect

    Bhogi, Ashok Kumar, R. Vijaya; Ahmmad, Shaik Kareem; Kistaiah, P.

    2016-05-06

    Glasses with composition 15BaO-25Li{sub 2}O-(60-x)B{sub 2}O{sub 3} -xCuO (x= 0, 0.2, 0.4, 0.6, 0.8 and 1 mol%) were prepared by the conventional melt quenching technique. These glasses were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and density measurements. Optical absorption studies were carried out as a function of copper ion concentration. The optical absorption spectra of studied glasses containing copper oxide exhibit a single broad band around 761nm which has been assigned to the 2B{sub 1g}→2B{sub 2g} transition. From these studies, the variations in the values of glass transition temperature (T{sub g}) have been observed. The fundamental absorption edge has been determined from the optical absorption spectra. The values of optical band gap and Urbach energy were determined with increase in concentration of CuO. The variations in density, glass transition temperature, optical band gap and Urbach energy with CuO content have been discussed in terms of changes in the glass structure. The analysis of these results indicated that copper ions mostly exist in Cu{sup 2+} state in these glasses when the concentration of CuO ≤ 0.8 mol% and above this concentration copper ions seem to subsist in Cu{sup 1+} state.

  19. Intermolecular interaction of voriconazole analogues with model membrane by DSC and NMR, and their antifungal activity using NMR based metabolic profiling.

    PubMed

    Kalamkar, Vaibhav; Joshi, Mamata; Borkar, Varsha; Srivastava, Sudha; Kanyalkar, Meena

    2013-11-01

    The development of novel antifungal agents with high susceptibility and increased potency can be achieved by increasing their overall lipophilicity. To enhance the lipophilicity of voriconazole, a second generation azole antifungal agent, we have synthesized its carboxylic acid ester analogues, namely p-methoxybenzoate (Vpmb), toluate (Vtol), benzoate (Vbz) and p-nitrobenzoate (Vpnb). The intermolecular interactions of these analogues with model membrane have been investigated using nuclear magnetic resonance (NMR) and differential scanning calorimetric (DSC) techniques. The results indicate varying degree of changes in the membrane bilayer's structural architecture and physico-chemical characteristics which possibly can be correlated with the antifungal effects via fungal membrane. Rapid metabolite profiling of chemical entities using cell preparations is one of the most important steps in drug discovery. We have evaluated the effect of synthesized analogues on Candida albicans. The method involves real time (1)H NMR measurement of intact cells monitoring NMR signals from fungal metabolites which gives Metabolic End Point (MEP). This is then compared with Minimum Inhibitory Concentration (MIC) determined using conventional methods. Results indicate that one of the synthesized analogues, Vpmb shows reasonably good activity.

  20. Unexpected solvent impact in the crystallinity of praziquantel/poly(vinylpyrrolidone) formulations. A solubility, DSC and solid-state NMR study.

    PubMed

    Costa, Emanuel D; Priotti, Josefina; Orlandi, Silvina; Leonardi, Darío; Lamas, María C; Nunes, Teresa G; Diogo, Hermínio P; Salomon, Claudio J; Ferreira, M João

    2016-09-25

    The saturation solubility of PVP:PZQ physical mixtures (PMs) and solid dispersions (SDs) prepared from ethanol (E/E) or ethanol/water (E/W) by the solvent evaporation method at 1:1, 2:1 and 3:1 ratio (w/w) was determined. The presence of PVP improves the solubility of PZQ (0.31±0.01mg/mL). A maximum of 1.29±0.03mg/mL of PZQ in solution was achieved for the 3:1 SD (E/E). The amount of PZQ in solution depends on the amount of polymer and on the preparation method. Solid-state NMR (ssNMR) and DSC were used to understand this behavior. Results show that PMs are a mixture of crystalline PZQ with the polymer, while SDs show different degrees of drug amorphization depending on the solvent used. For E/W SDs, PZQ exists in amorphous and crystalline states, with no clear correlation between the amount of crystalline PZQ and the amount of PVP. For E/E SDs, formulations with a higher percentage of PZQ are amorphous with the components miscible in domains larger than 3nm ((1)H ssNMR relaxation measurements). Albeit its higher saturation solubility, the 3:1 E/E PVP:PZQ sample has a significant crystalline content, probably due to the water introduced by the polymer. High PVP content and small crystal size account for this result.

  1. DSC and optical studies on BaO-Li2O-B2O3-CuO glass system

    NASA Astrophysics Data System (ADS)

    Bhogi, Ashok; Kumar, R. Vijaya; Ahmmad, Shaik Kareem; Kistaiah, P.

    2016-05-01

    Glasses with composition 15BaO-25Li2O-(60-x)B2O3 -xCuO (x= 0, 0.2, 0.4, 0.6, 0.8 and 1 mol%) were prepared by the conventional melt quenching technique. These glasses were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and density measurements. Optical absorption studies were carried out as a function of copper ion concentration. The optical absorption spectra of studied glasses containing copper oxide exhibit a single broad band around 761nm which has been assigned to the 2B1g→2B2g transition. From these studies, the variations in the values of glass transition temperature (Tg) have been observed. The fundamental absorption edge has been determined from the optical absorption spectra. The values of optical band gap and Urbach energy were determined with increase in concentration of CuO. The variations in density, glass transition temperature, optical band gap and Urbach energy with CuO content have been discussed in terms of changes in the glass structure. The analysis of these results indicated that copper ions mostly exist in Cu2+ state in these glasses when the concentration of CuO ≤ 0.8 mol% and above this concentration copper ions seem to subsist in Cu1+ state.

  2. Crystallization kinetic of Sb-V2O5-TeO2 glasses investigated by DSC and their elastic moduli and Poisson's ratio

    NASA Astrophysics Data System (ADS)

    Souri, Dariush

    2015-01-01

    Ternary tellurate glasses of the form xSb-(60-x)V2O5-40TeO2 (0≤x≤15 in mol%) were prepared by using the usual melt quenching method. Differential scanning calorimetry (DSC) at different heating rates (φ) was used to thermal analyze and to gain more insight in to the thermal stability, glass forming tendency and so calorimetric behavior of the present glasses. The glass transition temperature (Tg), the temperature corresponding to the onset of crystallization (Tx) and also the crystallization temperature (TCr) were obtained at different heating rates, to estimate the key kinetic parameter of activation energy of crystallization (ΔE) by using different empirical formulas. Also some other thermal parameters such as thermal stability and glass forming tendency were determined. It was found that Tg, Tx and TCr increase with increase in Sb content and also with increase in heating rate. Moreover, Makishima-Makenzie's theory was employed to evaluate the Poisson's ratio and elastic moduli, indicating a strong relation between elastic properties and the structure of glass. From the mechanical and thermal data and also the values of oxygen molar volume ( V O *), it was founded that the glass systems can be divided in to "two compositional regions"; so, results indicate that glasses with 10≤x≤15 (especially for x=12) are more thermal stable and strong glasses, which make them as more useful and promising materials in technological advantages and device manufacturing.

  3. Fundamental DSC investigations of alpha-keratinous materials as basis for the interpretation of specific effects of chemical, cosmetic treatments on human hair.

    PubMed

    Wortmann, F-J; Sendelbach, G; Popescu, C

    2007-01-01

    Alpha-keratinous materials can be considered as two-phase, filament/matrix composites, in which partly crystalline, alpha-helical intermediate filaments (if) are embedded in an amorphous matrix of IF-associated proteins (IFAP). Differential Scanning Calorimetry (DSC) of keratins in water was found to be especially suited to analyze various aspects of the thermal stability of these main morphological components. Results and considerations are reviewed, which were gained by applying the principles derived from fundamental investigations to the specific effects of oxidation (bleaching) and reduction (perm-waving). Properties and interactions of the main morphological components of human hair are considered that are specifically related to the various aspects of their thermal stability. The overall view of the results shows that the course of the thermal unfolding of the alpha-helix in the IFs is independent of the chemical history of hair. The matrix properties are the primary factor controlling the kinetics of the onset of the denaturation process in the IF/IFAP-composite.

  4. Application of differential scanning calorimetry (DSC), HPLC and pNMR for interpretation primary crystallisation caused by combined low and high melting TAGs.

    PubMed

    Saadi, Sami; Ariffin, Abdul Azis; Ghazali, Hasanah Mohd; Miskandar, Mat Sahri; Boo, Huey Chern; Abdulkarim, Sabo Mohammed

    2012-05-01

    The main goal of the present work was to assess the mechanism of crystallisation, more precisely the dominant component responsible for primary crystal formations and fat agglomerations. Therefore, DSC results exhibited significant effect on temperature transition; peak sharpness and enthalpy at palm stearin (PS) levels more than 40wt.%. HPLC data demonstrated slight reduction in the content of POO/OPO at PS levels less than 40wt.%, while the excessive addition of PS more than 40wt.% increased significantly PPO/POP content. The pNMR results showed significant drop in SFC for blends containing PS less than 40wt.%, resulting in low SFC less than 15% at body temperature (37°C). Moreover, the values of viscosity (η) and shear stress (τ) at PS levels over 40wt.% expressed excellent internal friction of the admixtures. All the data reported indicate that PPO/POP was the major component of primary nucleus developed. In part, the levels of PS should be less than 40wt.%, if these blends are designed to be used for margarine production.

  5. Temperature-controlled poly(propylene) glycol hydrophobicity on the formation of inclusion complexes with modified cyclodextrins. A DSC and ITC study.

    PubMed

    De Lisi, R; Lazzara, G; Milioto, S

    2011-07-21

    The study highlighted the main forces driving the formation of hydroxypropyl-cyclodextrins (HP-CDs) + poly(propylene) glycol 725 g mol(-1) inclusion complexes. The temperature parameter was chosen as the variable to modulate the hydrophobicity of the polymer, and consequently ITC experiments as functions of temperature as well as DSC measurements were done in a systematic way. The polymer is not included into HP-α-CD, it is strongly bound to HP-β-CD and it is floating in HP-γ-CD. The stability of the inclusion complexes is entropy controlled. The gain of the entropy is a unique result compared to the opposite literature findings for inclusion complexes based on polymers and CDs. This peculiarity is ascribable to the removal of water molecules from cages during complexation and this effect compensates the entropy loss due to constraints caused by the CD threading. In spite the host-guest van der Waals contacts are optimized, the enthalpies for the inclusion complex formation are positive and reveal the large heat required for dehydrating the propylene oxide units. All the macrocycles enhanced the polymer solubility in water. Increasing the affinity of the macrocycle to the macromolecule makes more expanded the one-phase area of the binodal curve. A new thermodynamic approach was proposed to predict quantitatively the binodal curve as well as the dependence of the enthalpy of separation phase on the macrocycle composition. The agreement between the experimental data and the computed values was excellent.

  6. Morphology of blends of linear and long-chain-branched polyethylenes in the solid state: A study by SANS, SAXS, and DSC

    SciTech Connect

    Wignall, G.D.; Londono, J.D.; Lin, J.S.; Alamo, R.G.; Galante, M.J.; Mandelkern, L.

    1995-04-24

    Differential scanning calorimetry (DSC), small-angle neutron scattering (SANS), and X-ray scattering (SAXS) have been used to investigate the solid-state morphology of blends of linear (high density) and long-chain-branched (low-density) polyethylenes (HDPE/LDPE). The blends are homogeneous in the melt, as previously demonstrated by SANS using the contrast obtained by deuterating the linear polymer. However, due to the structural and melting point differences ({approximately} 20 C) between HDPE and LDPE, the components may phase segregate on slow cooling (0.75 C/min). For high concentrations ({phi} {ge} 0.5) of HDPE, relatively high rates of crystallization of the linear component lead to the formation of separate stacks of HDPE and LDPE lamellae, as indicated by two-peak SAXS curves. For predominantly branched blends, the difference in crystallization rate of the components becomes smaller and only one SAXS peak is observed, indicating that the two species are in the same lamellar stack. Moreover, the phases no longer consist of the pure component and the HDPE lamellae contain up to 15--20% LDPE (and vice versa). Rapid quenching into dry ice/2-propanol ({minus}78 C) produces only one SAXS peak (and hence one lamellar stack) over the whole concentration range. The blends show extensive cocrystallization, along with a tendency for the branched material to be preferentially located in the amorphous interlamellar regions. For high concentrations ({phi} > 0.5) of HDPE-D, the overall scattering length density (SLD) is high and the excess concentration of LDPE between the lamellae enhances the SLD contrast between the crystalline and amorphous phases. Thus, the interlamellar spacing (long period) is clearly visible in the SANS pattern. The blend morphology is a strong function of the quenching rate, and samples quenched less rapidly (e.g., into water at 23 C) are similar to slowly cooled blends.

  7. The enthalpy of transformation of Ca(OH)2-I (portlandite) to Ca(OH)2-II (EuI2 structure) by low-temperature DSC

    NASA Astrophysics Data System (ADS)

    Schoenitz, M.; Navrotsky, A.; Leinenweber, K.

    Thermodynamic properties of high-pressure minerals that are not recoverable from synthesis experiments by conventional quenching methods (``unquenchable'' phases) usually are calculated from equation of state data and phase diagram topologies. The present study shows that, with cryogenic methods of recovery and sample treatment, phases with a suitable decomposition rate can be made accessible to direct thermodynamic measurements. A set of samples of Ca(OH)2-II has been synthesized in a multianvil device and subsequently recovered by cooling the high-pressure assembly with liquid nitrogen. Upon heating from liquid nitrogen to room temperature, the material transformed back to Ca(OH)2-I. The heat effect of this backtransformation was measured by differential scanning calorimetry. A commercial differential scanning calorimeter (Netzsch DSC 404), modified to allow sample loading at liquid nitrogen temperature was used to heat the material from -150 to +200°C at rates varying between 5 and 15°Cmin-1. The transformation started around -50°C very gradually, and peaked at about 0°C. To obtain a baseline correction, each sample was scanned under exactly the same conditions after the backtransformation was complete. Because of the relative sluggishness, onset and offset temperatures were not well defined as compared to fast (e.g., melting) reactions. To aid in integration, the resulting signals were successfully fitted using a generic asymmetric peak model. The enthalpy of backtransformation was determined to be ΔH=-10.37+/-0.50kJ mol-1. From previous in situ X-ray diffraction experiments, the location of the direct transformation in P-T space has been constrained to 5.7+/-0.4GPa at 500°C (Kunz etal. 1996). With the reaction volume known from the same study, and assuming that ΔCp of the transformation remains negligible between the conditions of our measurements and 500°C, our result gives an estimate of the entropy of transition and the P-T slope of the reaction

  8. Archeomagnetic dating of the eruption of Xitle volcano (Mexico) from a reappraisal of the paleointensity with the MSP-DSC protocol.

    NASA Astrophysics Data System (ADS)

    Bravo-Ayala, Manuel; Camps, Pierre; Alva-Valdivia, Luis; Poidras, Thierry; Nicol, Patrick

    2014-05-01

    The Xitle volcano, located south of Mexico City, is a monogenic volcano that has provided seven lava flows in a time interval of a few years. The age of these eruptions, estimated by means of radiocarbon dates on charcoal from beneath the flows, is still very poorly known, ranging from 4765±90 BC to 520±200 AD (see Siebe, JVGR, 2000 for a review). This lava field was emplaced over the archaeological city of Cuicuilco whose occupation is estimated between 700 BC and 150 AD. Thus a question is still pending: Is the downfall of Cuicuilco directly attributable to the eruption of Xitle? It seems that the answer is negative if we consider the latest radiocarbon dating by Siebe (2000), which sets the age of the eruption to 280±35 AD, that is significantly younger to the abandon of the city. Because this new age has direct implications on the history of the movements of ancient populations in the Central Valley of Mexico, we propose in the present study to check this estimate by archaeomagnetic dating. Xitle lava have been investigated several times for paleomagnetism, including directional analyses and absolute paleointensity determinations (see Alva, EPS, 57, 839-853, 2005 for a review). The characteristic Remanence direction is precisely determined. It is much more difficult to estimate precisely the paleointensity with the Thellier method: values scatter between 40 and 90 μT in a single flow (Alva, 2005). We propose here to estimate the paleointensity by means of the MSP-DSC protocol (Fabian and Leonhardt, 2010) with the new ultra-fast heating furnace FUReMAG developed in Montpellier (France). The sampling was performed along four profiles, one vertical through the entire thickness of the flow and three horizontal (at the top, middle and the bottom of the flow). Our preliminary results show that there is no difference between the values found in the different profiles, all providing a value around 62 μT. The comparison of our results (Dec = 359.0°, Inc = 35.2

  9. Eine Auswertmethode für DSC-Kurven binärer Gemische sowie die Phasendiagramme einige rMethylchlorsilane mit Lutidin / A New Evaluation of DSC-curves of Binary Mixtures and the Phase Diagrams of Some Methylchlorosilanes with Lutidine

    NASA Astrophysics Data System (ADS)

    Hensen, Karl; Dräbing, Michael

    1989-12-01

    A new evaluation of DSC-curves of binary mixtures is given. By analyzing the phase diagrams of methyltrichlorosilane and dimethyldichlorosilane with some lutidines the existence of the incongruently melting addition compounds MeSiCl3 · (2.3-Lutidine)-,, MeSiCl3 · 2.3-Lutidine, (MeSiCl3)2 · 3.4-Lutidine, Me,SiCl2 · (2.3-Lutidine)2, Me2SiCl2 · (2.5-Lutidine),, Me2SiCl2 · 2.5-Lutidine, Me2SiCl2 · (2.6-Lutidine)2, Me2SiCl2 · 2.6-Lutidine, Me2SiCl2 · (3.4-Lutidine)2, Me,SiCl2 · 3.4-Lutidine, (Me2SiCl2)2 · 3.4-Lutidine, Me2SiCl2 · (3.5-Lutidine)2, Me2SiCl2 · 3.5-Lutidine, and the congruently melting compound MeSiCl3 ·(3.4-Lutidine)2 was proven.

  10. An investigation into the release of cefuroxime axetil from taste-masked stearic acid microspheres. III. The use of DSC and HSDSC as means of characterising the interaction of the microspheres with buffered media.

    PubMed

    Robson, H; Craig, D Q; Deutsch, D

    2000-05-25

    Stearic acid coated cefuroxime axetil (SACA) microspheres have been studied using differential scanning calorimetry (DSC) and high sensitivity DSC (HSDSC) in order to examine the interaction between the spheres and a range of buffer systems, with a view to further enhance the understanding of the mechanism of drug release developed in earlier studies [Robson et al., 1999, 2000]. DSC studies indicated that after immersion in Sorensens modified phosphate buffer (SMPB) pH 5.9 followed by washing and drying, no change in the thermal properties of the spheres was detected up to 60 min of immersion, with a single endotherm noted at circa 56 degrees C, that corresponded to the melting of the stearic acid used in this study; similar results were obtained for systems immersed in distilled water. After immersion in SMPB pH 7.0 and 8.0, however, a second peak was noted at approximately 67 degrees C that increased in magnitude relative to the lower temperature endotherm with increasing exposure time to the medium. Spheres that had not been previously washed prior to drying showed complete conversion to the higher temperature endotherm for these two buffers. Systems which had been exposed to a range of pH 7.0 buffers (citrate-phosphate buffer (CPB), phosphate buffer mixed (PBM), boric acid buffer (BAB)) were then examined. Only the CPB systems showed evidence for conversion to the higher melting form. PBM systems to which further sodium had been added were then examined. A maximum conversion was found at 0.05 M sodium, which was in agreement with the maximum in release rate found in a previous study [Robson et al., 2000]. HSDSC was then used to examine systems that were immersed in the buffer. For SMPB, pH 5.9 and distilled water, only the endotherm corresponding to the stearic acid melting was seen. However, for SMPB pH 7.0 and 8.0, three peaks were seen, two corresponding to those seen for the DSC studies and a further lower temperature peak at circa 44 degrees C. Studies on

  11. Dsc E3 ligase localization to the Golgi requires the ATPase Cdc48 and cofactor Ufd1 for activation of sterol regulatory element-binding protein in fission yeast.

    PubMed

    Burr, Risa; Ribbens, Diedre; Raychaudhuri, Sumana; Stewart, Emerson V; Ho, Jason; Espenshade, Peter J

    2017-09-29

    Sterol regulatory element-binding proteins (SREBPs) in the fission yeast Schizosaccharomyces pombe regulate lipid homeostasis and the hypoxic response under conditions of low sterol or oxygen availability. SREBPs are cleaved in the Golgi through the combined action of the Dsc E3 ligase complex, the rhomboid protease Rbd2, and the essential ATPases associated with diverse cellular activities (AAA(+)) ATPase Cdc48. The soluble SREBP N-terminal transcription factor domain is then released into the cytosol to enter the nucleus and regulate gene expression. Previously, we reported that Cdc48 binding to Rbd2 is required for Rbd2-mediated SREBP cleavage. Here, using affinity chromatography and mass spectrometry experiments, we identified Cdc48-binding proteins in S. pombe, generating a list of many previously unknown potential Cdc48-binding partners. We show that the established Cdc48 cofactor Ufd1 is required for SREBP cleavage but does not interact with the Cdc48-Rbd2 complex. Cdc48-Ufd1 is instead required at a step prior to Rbd2 function, during Golgi localization of the Dsc E3 ligase complex. Together, these findings demonstrate that two distinct Cdc48 complexes, Cdc48-Ufd1 and Cdc48-Rbd2, are required for SREBP activation and low-oxygen adaptation in S. pombe. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Is the pre-Tg DSC endotherm observed with solid state proteins associated with the protein internal dynamics? Investigation of bovine serum albumin by solid state hydrogen/deuterium exchange.

    PubMed

    Mizuno, Masayasu; Pikal, Michael J

    2013-10-01

    DSC thermograms of solid state pure proteins often show a distinct endotherm at a temperature far below the glass transition temperature of the system (Tg). We hypothesized this endotherm represents enthalpy recovery associated with an internal mobility transition of the protein molecule. Although the existence of an internal transition has been postulated, whether this endotherm is associated with such a transition has not previously been discussed. The purpose of this study was to investigate the origin of the pre-Tg endotherm in lyophilized bovine serum albumin (BSA). Due to strong glass behavior, the system Tg was determined by extrapolating Tg data of disaccharide/BSA formulations to zero saccharide. A small pre-Tg endotherm around 40-60 °C was observed in amorphous BSA equilibrated at 11%RH. The apparent activation energy suggested the endotherm was "α-mobility"-related. A solid state hydrogen/deuterium exchange study using FTIR was conducted over a temperature range spanning the endotherm. We found a fast phase, followed by essentially a plateau level which is highly temperature dependent in the 40-60 °C range, suggesting enhanced internal protein motion as the system passes through the temperature range of the endotherm. These results suggest the pre-Tg endotherm is associated with a protein internal mobility transition.

  13. Correlation of the penetration enhancement with the influence of an alcohol/tocopheryl polyethylene glycol succinate (TPGS) cosolvent system on the molecular structure of the stratum corneum of nude mouse skin as examined by microscopic FTIR/DSC

    NASA Astrophysics Data System (ADS)

    Liou, Yi-Bo; Ho, Hsiu-O.; Chen, Shin-Yi; Sheu, Ming-Thau

    2009-10-01

    Tocopheryl polyethylene glycol succinate (TPGS) is a water-soluble derivative of natural source of vitamin E, which possesses a dual nature of lipophilicity and hydrophilicity, similar to a surface-active agent. The penetration enhancement of estradiol by an ethanol and TPGS cosolvent system (EtOH/TPGS) has been confirmed. In this study, the correlation of the penetration enhancement with the influence of the EtOH/TPGS cosolvent system on biophysical changes of the stratum corneum (SC) as examined by Fourier transformation infrared spectrometry differential scanning calorimetry (FTIR/DSC) was investigated. Thermotropic changes in the asymmetrical and symmetrical C-H stretching of hydrocarbon chains of lipids, and amide I and II bands that characterize the protein structure of the SC treated with different concentrations of the EtOH/TPGS cosolvent were examined in this investigation. Results demonstrated that a strong correlation of the influence on biophysical changes of the SC treated with the EtOH/TPGS cosolvent system with the penetration enhancement of estradiol by the corresponding cosolvent system was not evident. It was concluded that the incorporation of TPGS in the cosolvent system seemed only to have insignificantly modified the structural features of the SC. It was not obvious that the penetrant had encountered these modifications resulting in an improvement in the penetration of estradiol by TPGS.

  14. Use of DSC and DMA Techniques to Help Investigate a Material Anomaly for PTFE Used in Processing a Piston Cup for the Urine Processor Assembly (UPA) on International Space Station (ISS)

    NASA Technical Reports Server (NTRS)

    Wingard, Doug

    2010-01-01

    Human urine and flush water are eventually converted into drinking water with the Urine Processor Assembly (UPA) aboard the International Space Station (ISS). This conversion is made possible through the Distillation Assembly (DA) of the UPA. One component of the DA is a molded circular piston cup made of virgin polytetrafluoroethylene (PTFE). The piston cup is assembled to a titanium component using eight fasteners and washers. Molded PTFE produced for spare piston cups in the first quarter of 2010 was different in appearance and texture, and softer than material molded for previous cups. For the suspect newer PTFE material, cup fasteners were tightened to only one-half the required torque value, yet the washers embedded almost halfway into the material. The molded PTFE used in the DA piston cup should be Type II, based on AMS 3667D and ASTM D4894 specifications. The properties of molded PTFE are considerably different between Type I and II materials. Engineers working with the DA thought that if Type I PTFE was molded by mistake instead of Type II material, that could have resulted in the anomalous material properties. Typically, the vendor molds flat sheet PTFE from the same material lot used to mold the piston cups, and tensile testing as part of quality control should verify that the PTFE is Type II material. However, for this discrepant lot of material, such tensile data was not available. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were two of the testing techniques used at the NASA/Marshall Space Flight Center (MSFC) to investigate the anomaly for the PTFE material. Other techniques used on PTFE specimens were: Shore D hardness testing, tensile testing on dog bone specimens and a qualitative estimation of porosity by optical and scanning electron microscopy.

  15. Binding of cationic peptides (KX)4K to DPPG bilayers. Increasing the hydrophobicity of the uncharged amino acid X drives formation of membrane bound β-sheets: A DSC and FT-IR study.

    PubMed

    Hädicke, André; Blume, Alfred

    2016-06-01

    The binding of cationic peptides of the sequence (KX)4K to lipid vesicles of negatively charged dipalmitoyl-phosphatidylglycerol (DPPG) was investigated by differential scanning calorimetry (DSC) and temperature dependent Fourier-transformed infrared (FT-IR) spectroscopy. The hydrophobicity of the uncharged amino acid X was changed from G (glycine) over A (alanine), Abu (α-aminobutyric acid), V (valine) to L (leucine). The binding of the peptides caused an increase of the phase transition temperature (Tm) of DPPG by up to 20°C. The shift depended on the charge ratio and on the hydrophobicity of the amino acid X. Unexpectedly, the upward shift of Tm increased with increasing hydrophobicity of X. FT-IR spectroscopy showed a shift of the CH2 stretching vibrations of DPPG to lower frequency, particularly for bilayers in the liquid-crystalline phase, indicating an ordering of the hydrocarbon chains when the peptides were bound. Changes in the lipid C=O vibrational band indicated a dehydration of the lipid headgroup region after peptide binding. (KG)4K was bound in an unordered structure at all temperatures. All other peptides formed intermolecular antiparallel β-sheets, when bound to gel phase DPPG. However, for (KA)4K and (KAbu)4K, the β-sheets converted into an unordered structure above Tm. In contrast, the β-sheet structures of (KV)4K and (KL)4K remained stable even at 80°C when bound to the liquid-crystalline phase of DPPG. Strong aggregation of DPPG vesicles occurred after peptide binding. For the aggregates, we suggest a structure, where aggregated single β-sheets are sandwiched between opposing DPPG bilayers with a dehydrated interfacial region.

  16. Spin crossover in iron(II) tris(2-(2 '-pyridyl)benzimidazole) complex monitored by variable temperature methods: synchrotron powder diffraction, DSC, IR spectra, Mössbauer spectra, and magnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Boča, R.; Boča, M.; Ehrenberg, H.; Fuess, H.; Linert, W.; Renz, F.; Svoboda, I.

    2003-09-01

    The thermal expansion of the spin crossover system [Fe(pybzim) 3](ClO 4) 2 · H 2O (pybzim=2-(2 '-pyridyl)benzimidazole) has been determined from powder X-ray data between 50 and 250 K; the wavelength of the synchrotron source was 1.21888(1) Å. The unit cell parameters of the triclinic crystal system were a=12.091 Å, b=12.225 Å, c=14.083 Å, α=77.70°, β=80.35°, γ=74.35°, and V=1944.9 Å 3 at 250 K. In addition to the linear thermal expansion of the unit cell volume, an extra expansion due to the low-spin (LS) to high-spin (HS) transition is observed. The V( T) function shows a sudden increase comparable with the step in the effective magnetic moment at the transition region (140 K). A similar behavior is obtained on the basis of the infrared spectra. The absorption bands corresponding to the metal-ligand stretching modes change their intensities upon heating: the bands corresponding to the low-spin molecules (at ca. 409, 430, 443, and 460 cm -1) disappear in the gain of the high-spin bands (at 259 and 285 cm -1). The variable-temperature data obtained by different techniques (powder diffraction, EXAFS, IR spectra, Mössbauer spectra, magnetic susceptibility, DSC) have been transformed to a common basis - the temperature dependence of the high-spin mole fraction xHS( T). The application of the Ising-like (two-level) model of the spin crossover led to the thermodynamic data Δ H=2.6 kJ mol -1 and Δ S=19 J K -1 mol -1 as well as to the cooperativeness J/ k≈110 K (subtracted from the susceptibility data) that characterizes the abruptness of the spin crossover in the solid state.

  17. Dynamic contrast-enhanced susceptibility-weighted perfusion MRI (DSC-MRI) in a glioma model of the rat brain using a conventional receive-only surface coil with a inner diameter of 47 mm at a clinical 1.5 T scanner.

    PubMed

    Ulmer, Stephan; Reeh, Matthias; Krause, Joerg; Herdegen, Thomas; Heldt-Feindt, Janka; Jansen, Olav; Rohr, Axel

    2008-07-30

    Magnetic resonance (MR) imaging in animal models is usually performed in expensive dedicated small bore animal scanners of limited availability. In the present study a standard clinical 1.5 T MR scanner was used for morphometric and dynamic contrast-enhanced susceptibility-weighted MR imaging (DSC-MRI) of a glioma model of the rat brain. Ten male Wistar rats were examined with coronal T2-weighted, and T1-weighted images (matrix 128 x 128, FOV 64 mm) after implantation of an intracerebral tumor xenografts (C6) using a conventional surface coil. For DSC-MRI a T2*-weighted sequence (TR/TE=30/14 ms, matrix 64 x 64, FOV 90 mm; slice thickness of 1.5mm) was performed. Regions of interest were defined within the tumor and the non-affected contralateral hemisphere and the mean transit time (MTT) was determined. Tumor dimensions in MR predicted well its real size as proven by histology. The MTT of contrast agent passing through the brain was significantly decelerated in the tumor compared to the unaffected hemisphere (p<0.001, paired t-test), which is most likely due to the leakage of contrast agent through the disrupted blood brain barrier. This setup offers advanced MR imaging of small animals without the need for dedicated animal scanners or dedicated custom-made coils.

  18. A.C. impedance, XRD, DSC, SEM and charge/discharge studies on Al2O3, TiO2, SiO2 dispersoid LiPF6/PVC/PVdF-co-HFP composite polymer electrolytes by phase inversion

    NASA Astrophysics Data System (ADS)

    Vickraman, P.; Gopukumar, S.

    2017-07-01

    The PVC/PVdF-co-HFP composite polymer electrolyte membranes (CPEMs) by varying blend ratios 1:1, 1:2, and 2:1 with fixed content of Al2O3, TiO2 and SiO2 having soaked in 0.5 M LiPF6 in EC/DEC (1:1) v/v) have been prepared by phase inversion. CPEMs of higher ionic conductivity (not dependent on electrolyte uptake as observed in our study) ASA4 (3.61×10-4 Scm-1), TSA3 (1.53×10-4 Scm-1), and SSA3 (4.81×10-4 Scm-1) have been only chosen for XRD, DSC, SEM and electrochemical studies. In XRD, crystalline peaks (phases) of PVdF have been noted with/without change in intensity as well as FWHM which correspond to type of filler interaction with host matrix. In DSC, it is observed that shifts in baseline, melting endotherms, and area under the endotherms indicating the thermal hist ory of PVC (Tg = 82 ° C) and melting of VdF crystallites varied with nature of the filler dispersoid. In SEM, the coagulated fibrils of the polymer coiled with the sponge like structure has been mapped. The charge/discharge studies are carried out on these CPEMs at C/10 rate in the voltage range 2.8 V - 4.2 V, and it is noted that the TSA3 showed better cycling performance with good capacity retention i.e., 50 cycles with 66% capacity retention than ASA4 of 28 cycles with 65% and SSA3 of 5 cycles with 56%. In the present study Coulombic efficiency is concerned only for first cycle and it is noted that the TSA3 showed 71% than 66% and 62% respectively for SSA3 and ASA4.

  19. Vladimir Janda, MD, DSc: tribute to a master of rehabilitation.

    PubMed

    Morris, Craig E; Greenman, Philip E; Bullock, Margaret I; Basmajian, John V; Kobesova, Alena

    2006-04-20

    The purpose of this presentation is to pay tribute to the life's work of Professor Vladimir Janda, a key figure in the 20th Century rehabilitation movement. An accomplished neurologist, he founded the rehabilitation department at Charles University Hospital in Prague, Czechoslovakia. He was one of the seminal members of the Prague school of manual medicine and rehabilitation that expanded its influence throughout Central and Eastern Europe. His observations regarding muscle imbalances, faulty posture and gait, and their association with chronic pain syndromes, etiologically, diagnostically, and therapeutically, influenced the rehabilitation world. The authors comprise a multinational, multiprofessional group representative of rehabilitation specialists around the world who would like to pay tribute and give a final word of thanks to this innovative educator, clinician, and author.

  20. Crystallization of Polymers Investigated by Temperature-Modulated DSC

    PubMed Central

    Righetti, Maria Cristina

    2017-01-01

    The aim of this review is to summarize studies conducted by temperature-modulated differential scanning calorimetry (TMDSC) on polymer crystallization. This technique can provide several advantages for the analysis of polymers with respect to conventional differential scanning calorimetry. Crystallizations conducted by TMDSC in different experimental conditions are analysed and discussed, in order to illustrate the type of information that can be deduced. Isothermal and non-isothermal crystallizations upon heating and cooling are examined separately, together with the relevant mathematical treatments that allow the evolution of the crystalline, mobile amorphous and rigid amorphous fractions to be determined. The phenomena of ‘reversing’ and ‘reversible‘ melting are explicated through the analysis of the thermal response of various semi-crystalline polymers to temperature modulation. PMID:28772807

  1. [MSW incineration fly ash melting by DSC-DTA].

    PubMed

    Li, Rundong; Chi, Yong; Li, Shuiqing; Wang, Lei; Yan, Jianhua; Cen, Kefa

    2002-07-01

    Melting characteristics of two kinds of municipal solid waste incineration(MSWI) fly ash were studied in this paper by high temperature differential scanning calorimetry and differential temperature analysis. MSWI fly ash was considered as hazardous waste because it contains heavy metals and dioxins. The experiments were performed in either N2 or O2 atmosphere in temperature range of 20 degrees C-1450 degrees C at various heating rates. Two different MSW incineration fly ashes used in the experiments were collected from our country and France respectively. The process of fly ash melting exhibits two reactions occurring at temperature ranges of about 480 degrees C-670 degrees C and 1136 degrees C-1231 degrees C, respectively. The latent heat of polymorphic transformation and fusion were approximately 20 kJ/kg and 700 kJ/kg, while the total heat required for melting process was about 1800 kJ/kg. The paper also studied effect of CaO to melting. A heat flux thermodynamic model for fly ash melting was put forward and it agrees well with experimental data.

  2. DSC and Raman studies of silver borotellurite glasses

    SciTech Connect

    Kaur, Amandeep; Khanna, Atul; Gonzàlez, Fernando

    2016-05-23

    Silver borotellurite glasses of composition: xAg{sub 2}O-yB{sub 2}O{sub 3}-(100-x-y)TeO{sub 2} (x=20-mol%, y = 0, 10, 20 and 30-mol%) were prepared and characterized by density, X-ray diffraction (XRD), differential scanning calorimetry, and Raman spectroscopy. XRD confirmed the amorphous structure of all samples. Density of glasses decreases while the glass transition temperature increases with increase in B{sub 2}O{sub 3} content from 10 to 30-mol%. Raman study shows that coordination number of Te with oxygen decreases steadily from 3.42 to 3.18 on adding B{sub 2}O{sub 3} due to the transformation of TeO{sub 4} into TeO{sub 3} units.

  3. Parental Income and College Opportunity. DSC Report Series.

    ERIC Educational Resources Information Center

    Manski, Charles F.

    This paper describes recent patterns of income stratification in American colleges. Data from the Current Population Survey provide estimates of college enrollment stratification by income during the period 1970-1988. The National Longitudinal Study of the High School Class of 1972 and the High School and Beyond survey provide data for two cohorts…

  4. DSC and Raman studies of silver borotellurite glasses

    NASA Astrophysics Data System (ADS)

    Kaur, Amandeep; Khanna, Atul; Gonzàlez, Fernando

    2016-05-01

    Silver borotellurite glasses of composition: xAg2O-yB2O3-(100-x-y)TeO2 (x=20-mol%, y = 0, 10, 20 and 30-mol%) were prepared and characterized by density, X-ray diffraction (XRD), differential scanning calorimetry, and Raman spectroscopy. XRD confirmed the amorphous structure of all samples. Density of glasses decreases while the glass transition temperature increases with increase in B2O3 content from 10 to 30-mol%. Raman study shows that coordination number of Te with oxygen decreases steadily from 3.42 to 3.18 on adding B2O3 due to the transformation of TeO4 into TeO3 units.

  5. Determination of Purity by Differential Scanning Calorimetry (DSC).

    ERIC Educational Resources Information Center

    Brown, M. E.

    1979-01-01

    An exercise is presented which demonstrates the determination of sample purity by differential scanning calorimetry. Data and references are provided to enable the exercise to be carried out as a dry-lab experiment. (BB)

  6. The glass transition process in humid biopolymers. DSC study

    NASA Astrophysics Data System (ADS)

    Grunina, N. A.; Belopolskaya, T. V.; Tsereteli, G. I.

    2006-05-01

    Thermal properties of native and denatured biopolymers with quite different chemical and steric structure (globular and fibrillar proteins, DNA, starches) were studied by means of differential scanning calorimetry in a wide range of temperatures and concentrations of water. It was shown that both native and denatured humid biopolymers are glassy systems. The glass transition temperature of these systems strongly depends on percentage of water, with water being simultaneously an intrinsic element of systems' ordered structure and a plasticizer of its amorphous state. On the base of the absolute values of heat capacities for biopolymer-water systems as a whole, heat capacities for biopolymers themselves were calculated as functions on water concentration at fixed temperatures. The S-shaped change of heat capacity observed on diagrams of state both for native and denatured biopolymers is the manifestation of biopolymers' passing through the vitrification region, as it occurs for denatured samples at heating.

  7. Determination of Purity by Differential Scanning Calorimetry (DSC).

    ERIC Educational Resources Information Center

    Brown, M. E.

    1979-01-01

    An exercise is presented which demonstrates the determination of sample purity by differential scanning calorimetry. Data and references are provided to enable the exercise to be carried out as a dry-lab experiment. (BB)

  8. Density, DSC, X-ray and NMR measurements through the gel and lamellar phase transitions of 1-myristoyl-2-stearoyl-sn-glycero-3-phosphatidylcholine (MSPC) and 1-stearoyl-2-myristoyl-sn-glycero-3-phosphatidylcholine (SMPC): observation of slow relaxation processes and mechanisms of phase transitions.

    PubMed

    Jones, J W; Lue, L; Saiani, A; Tiddy, G J T

    2012-04-28

    Dialkyl lecithin dispersions in water exhibit two phase transitions upon cooling from the lamellar phase (L(α)). At the main transition (T(M)) the L(α) phase changes to a ripple (gel) phase (P(β')) which then transforms to a second gel phase (L(β')) at the "pretransition" (T(P)). We have made accurate density measurements through the various phases for two lecithins having unequal chains: 1-myristoyl-2-stearoyl-sn-glycero-3-phosphatidylcholine (MSPC) and 1-stearoyl-2-myristoyl-sn-glycero-3-phosphatidylcholine (SMPC). The measurements were carried out over five heat/cool cycles from 5 to 55 °C, followed by cooling back to 5 °C. The samples were then held at 50 °C for 24 hours, followed by a further three cool/heat cycles. For SMPC we observe an increase in density of the gel phases over the first 5 cycles, followed by much smaller changes after incubation at 50 °C. The lamellar phase also shows an increase in density, albeit much smaller. This parallels the behaviour of 1,2-di-palmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and 1,2-di-myristoyl-sn-glycero-3-phosphatidylcholine (DMPC) reported earlier (Jones et al., Liquid Crystals 32, 1465 (2005)). For MSPC we observe a decrease in density within the gel phases while T(P) almost disappears after the first cycle. The lamellar phase shows little evidence of any change with each cycle. Within the lamellar phases there is a marked reduction in density on approaching T(M), which is attributed to the formation of transitory gel phase domains. Additional measurements by DSC and X-ray diffraction show that the changes in densities are not accompanied by large changes in transition enthalpies or phase structures. NMR data indicate that the pretransitional event within the L(α) phase is accompanied by ordering of the alkyl chains. The results indicate that the exact nature of the lipid alkyl chains could play a key role in the formation of gel phase patches within membrane bilayers. Their detailed chemical

  9. Containment control of networked autonomous underwater vehicles: A predictor-based neural DSC design.

    PubMed

    Peng, Zhouhua; Wang, Dan; Wang, Wei; Liu, Lu

    2015-11-01

    This paper investigates the containment control problem of networked autonomous underwater vehicles in the presence of model uncertainty and unknown ocean disturbances. A predictor-based neural dynamic surface control design method is presented to develop the distributed adaptive containment controllers, under which the trajectories of follower vehicles nearly converge to the dynamic convex hull spanned by multiple reference trajectories over a directed network. Prediction errors, rather than tracking errors, are used to update the neural adaptation laws, which are independent of the tracking error dynamics, resulting in two time-scales to govern the entire system. The stability property of the closed-loop network is established via Lyapunov analysis, and transient property is quantified in terms of L2 norms of the derivatives of neural weights, which are shown to be smaller than the classical neural dynamic surface control approach. Comparative studies are given to show the substantial improvements of the proposed new method. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  10. 7 CFR 1710.114 - TIER, DSC, OTIER and ODSC requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... limited to: all taxes, depreciation, maintenance expenses, and the cost of electric power and energy and other operating expenses of the electric system, including all obligations under the wholesale power... SERVICE, DEPARTMENT OF AGRICULTURE GENERAL AND PRE-LOAN POLICIES AND PROCEDURES COMMON TO ELECTRIC...

  11. DSC and TG Analysis of a Blended Binder Based on Waste Ceramic Powder and Portland Cement

    NASA Astrophysics Data System (ADS)

    Pavlík, Zbyšek; Trník, Anton; Kulovaná, Tereza; Scheinherrová, Lenka; Rahhal, Viviana; Irassar, Edgardo; Černý, Robert

    2016-03-01

    Cement industry belongs to the business sectors characteristic by high energy consumption and high {CO}2 generation. Therefore, any replacement of cement in concrete by waste materials can lead to immediate environmental benefits. In this paper, a possible use of waste ceramic powder in blended binders is studied. At first, the chemical composition of Portland cement and ceramic powder is analyzed using the X-ray fluorescence method. Then, thermal and mechanical characterization of hydrated blended binders containing up to 24 % ceramic is carried out within the time period of 2 days to 28 days. The differential scanning calorimetry and thermogravimetry measurements are performed in the temperature range of 25°C to 1000°C in an argon atmosphere. The measurement of compressive strength is done according to the European standards for cement mortars. The thermal analysis results in the identification of temperature and quantification of enthalpy and mass changes related to the liberation of physically bound water, calcium-silicate-hydrates dehydration and portlandite, vaterite and calcite decomposition. The portlandite content is found to decrease with time for all blends which provides the evidence of the pozzolanic activity of ceramic powder even within the limited monitoring time of 28 days. Taking into account the favorable results obtained in the measurement of compressive strength, it can be concluded that the applied waste ceramic powder can be successfully used as a supplementary cementing material to Portland cement in an amount of up to 24 mass%.

  12. DSC (Differential Scanning Calorimeter) Stability Test for Liquid Propellants: A Preliminary Report.

    DTIC Science & Technology

    1987-09-01

    AL 35898 1 Commander Commander Naval Air Systems Command US Army Missile and Space ATTN: J. Ramnarace, Intelligence Center AIR-54111C ATTN: AMSMI-YDL...uSE. .3o BUSIN S RE L MAIL FIRST CLASS PERMIT NO 12062 WASHINGTON,OCI 0IRTPOSTAGE WILL BE PAID BY DEPARTMENT OF THE ARMY Director US Army Ballistic

  13. Mechanisms of fibrinogen-acebutolol interactions: Insights from DSC, CD and LS.

    PubMed

    Hassan, Natalia; Ruso, Juan M; Somasundaran, P

    2011-02-01

    The complex formed due to the interaction of the amphiphilic betablocker acebutolol with fibrinogen in a buffer solution (50mN glycine, pH of 8.5) has been investigated using a multipronged physicochemical approach. Differential scanning calorimetry measurements of the complexes have shown no reversibility of thermal denaturation as indicated by the three observed peaks and the opposite role that acebutolol plays in the folding different domains of the fibrinogen molecule and the stability of such domains. While circular dichroism measurements have revealed that interaction of acebutolol with fibrinogen affects the protein secondary structure to a different extent depending on the temperature and drug concentration, dynamic light scattering analysis showed evidence for protein aggregation mainly to tetramers and dimers. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Exploration of Low-Glycemic-Impact Sugars and Polyols, using SRC, DSC, and RVA

    USDA-ARS?s Scientific Manuscript database

    The anti-plasticizing action of the high sucrose concentration in a cookie formula inhibits both gluten development during dough mixing and starch gelatinization/pasting during baking. If alternative sugars and polyols with lower glycemic impact are used to replace sucrose, the resulting absence of ...

  15. Structural, vibrational and DSC investigations of the bis-4-benzyl piperidinium tetraoxoselenate monohydrate crystal

    NASA Astrophysics Data System (ADS)

    Kessentini, Y.; Ben Ahmed, A.; Elaoud, Z.; Aljuaid, S. S.; Mhiri, T.

    2012-12-01

    A new organic-inorganic salt, bis-4-benzyl piperidinium tetraoxoselenate monohydrate has been synthesized and characterized by X-ray diffraction, FT-IR and FT-Raman spectroscopies. The title compound crystallizes in the monoclinic system P21/c at room temperature with the following parameters: a = 8.617(3) Å, b = 27.140(9) Å, c = 10.926(5) Å, β = 96.46(4)° and Z = 4. Its vibrational spectra have been discussed on the basis on quantum chemical density theory (DFT) calculation using B3LYP/6-31G∗ approach. The role of the intermolecular interaction in this crystal is analyzed. Acidic protons of the selenate group were transferred to the organic cation giving the singly-protonated cation. The ability of ions to form spontaneous three-dimensional structure through O-H⋯O and N-H⋯O hydrogen bond is fully utilized. These hydrogen bonds give notable vibrational effects.

  16. Exploration of functionality of low glycemic impact sugars and polyols using DSC, RVA, and cookie baking

    USDA-ARS?s Scientific Manuscript database

    Consumers' interest in healthy cookies is increasing, including expectations for prebiotic nutritional benefits and low glycemic impact. Plasticization of flour polymers is critical to mixing and baking for baked goods. However, concentrated sugar solutions act as anti-plasticizers compared to wat...

  17. Low-temperature phase behavior of fatty acid methyl esters by differential scanning calorimetry (DSC)

    USDA-ARS?s Scientific Manuscript database

    Fatty acid methyl ester (FAME) mixtures have many uses including biodiesel, lubricants, metal-working fluids, surfactants, polymers, coatings, green solvents and phase-change materials. The physical properties of a FAME mixture depends on the fatty acid concentration (FAC) profile. Some products hav...

  18. Structural refinement and DSC characterization of PEEK fiber. [Poly(aryletheretherketone)

    SciTech Connect

    Fratini, A.V.; Cross, E.M.; Whitaker, R.B.

    1986-06-03

    The crystalline structure of oriented fibers of poly(aryletheretherketone) (PEEK) has been analyzed by x-ray diffraction and refined by the Linked-Atom Least-Squares procedure. The conformation of chains, consisting of a six-aryl ring unit, is approximated by the refinement of a two-aryl ring unit within the orthorhombic unit subcell with dimensions: a = 7.83 +- 0.02 A, b = 5.94 +- 0.01 A, and c = 9.86 +- 0.04 A. Certain constraints imposed by Pbcn space group symmetry are relaxed during refinement. The results of the two-ring refinement indicate that a single torsion angle can be used to describe the conformation of the six-ring unit. The torsion angle corresponds to the average tilt of the phenylene rings out of the (100) face, and the best fit is obtained with an angle of 37/sup 0/. The simulated powder diffraction pattern based on the atomic coordinates of the six-ring unit matches very closely previously reported patterns for a variety of PEEK specimens. The analysis supports, and extends to oriented fibers, the previously reported finding that space group Pbcn is a valid representation for the structure of PEEK. Differential scanning calorimetry established that the PEEK samples were typical PEEK material.

  19. NMR, DSC and High Pressure Electrical Conductivity Studies on Liquid and Hybrid Electrolytes

    DTIC Science & Technology

    1998-07-01

    Electrolytes, Activation Volume, High Pressure 17. SECURITY CLASSIFICATION OF REPORT UNCLASSIFIED 18. SECURITY CLASSIFICATION OF THIS PAGE...UNCLASSIFIED 19. SECURITY CLASSIFICATION OF ABSTRACT UNCLASSFIED 15. NUMBER OF PAGES 16. PRICE CODE 20. LIMITATION OF ABSTRACT \\SN 75i0-O--230-550O...polyethers [43] and PAN [44] complexed with LiBF4 , indicating that for these materials the lithium ions reside near to their anion counterparts. Clearly

  20. Conductivity, DSC, FTIR, and NMR Studies of Poly(Vinyl Acetate) Complexed with Alkali Metal Salts.

    DTIC Science & Technology

    1985-09-01

    Crane, Indiana 47522 Norwood, Massachusetts 02062 S. Ruby Dr. Aaron Wold DOE (STOR) Department of Chemistry Room 5EO36 Forrestal Bldg., CE-14 Brown...Blum Dr. Donald Sandstrom Department of Physics Boeing Aerospace Co. University of Puerto Rico P.O. Box 3999 Rio Piedras , Puerto Rico 00931 Seattle

  1. Differential Scanning Calorimetric (DSC) Analysis of Rotary Nickel-Titanium (NiTi) Endodontic File (RNEF)

    NASA Astrophysics Data System (ADS)

    Wu, Ray Chun Tung; Chung, C. Y.

    2012-12-01

    To determine the variation of A f along the axial length of rotary nickel-titanium endodontic files (RNEF). Three commercial brands of 4% taper RNEF: GTX (#20, 25 mm, Dentsply Tulsa Dental Specialties, Tulsa, OK, USA), K3 (#25, 25 mm) and TF (Twisted File #25, 27 mm) (Sybron Kerr, Orange, CA, USA) were cut into segments at 4 mm increment from the working tip. Regional specimens were measured for differential heat-flow over thermal cycling, generally with continuous heating or cooling (5 °C/min) and 5 min hold at set temperatures (start, finish temperatures): GTX: -55, 90 °C; K3: -55, 45 °C; TF: -55, 60 °C; using differential scanning calorimeter. This experiment demonstrated regional differences in A f along the axial length of GTX and K3 files. Similar variation was not obvious in the TF samples. A contributory effect of regional difference in strain-hardening due to grinding and machining during manufacturing is proposed.

  2. Two decoupling methods for non-isothermal DSC results of AIBN decomposition.

    PubMed

    Zhang, Cai-Xing; Lu, Gui-Bin; Chen, Li-Ping; Chen, Wang-Hua; Peng, Min-Jun; Lv, Jia-Yu

    2015-03-21

    During thermal decomposition of azobisisobutyronitrile (AIBN), the endothermic process of phase transition disturbed exothermic decomposition, which brought deformation in its thermal graphs. Therefore, exact kinetic parameters of the decomposition could not be obtained by the existing kinetics analytic models, and the accurate enthalpy data of the decomposition and phase transition were not available. Two methods, i.e., a solvent method and a mathematical method, were introduced in this paper to resolve the coupling phenomenon. In the former method, AIBN was dissolved into aniline to eliminate the endothermic process and obtain curves of the liquid-state decomposition. In the latter method, MATLAB software was employed to get the "pure" exothermic decomposition curve without the influence of phase transition by fitting coupling curves within the section after the transition point and extrapolating to the initial stage of decomposition. Moreover, the kinetic parameters of the "pure" exothermic decomposition of AIBN obtained by the mathematical fitting agreed with the results from the solvent method, verifying the accuracy of the decoupling. The research is of great significance for comprehending the exact characteristics of thermal behaviors and safety parameters of AIBN. It also provides a great help to determine the safe operating temperature and alarm temperature for processes in industry.

  3. Antiferroelectric liquid crystals studied by DSC, electro-optic, and dielectric methods

    NASA Astrophysics Data System (ADS)

    Marzec, M.; Fafara, A.; Wrobel, S.; Godlewska, Malgorzata; Dabrowski, Roman S.; Czuprynski, Krzysztof L.; Haase, Wolfgang

    2000-05-01

    Thermal properties of four liquid crystalline substances exhibiting antiferroelectric SmCA* and ferroelectric SmC* phases were studied using differential scanning calorimetry, texture observation, electrooptic measurements and dielectric spectroscopy. The measurements were performed both on heating and cooling of the samples. All four substances studied in this work are characterized by a complex polymorphism. The temperatures of phase transitions and enthalpy changes associated with them were determined. The transition from the liquid crystalline to the crystalline state showed significant hysteresis for all four substances studied. Textures observations and electrooptic measurements were performed using ITO cells having thickness from 6 to 10 micrometers . The measurements of spontaneous polarization were performed by means of reversal current method. Spontaneous polarization was measured for a few frequencies of the triangular voltage applied. Temperature dependencies of spontaneous polarization have been studied as a function of the side chain structure.

  4. DSC deconvolution of the structural complexity of c-MYC P1 promoter G-quadruplexes.

    PubMed

    Dettler, Jamie M; Buscaglia, Robert; Le, Vu H; Lewis, Edwin A

    2011-03-16

    We completed a biophysical characterization of the c-MYC proto-oncogene P1 promoter quadruplex and its interaction with a cationic porphyrin, 5,10,15,20-tetra(N-methyl-4-pyridyl)porphyrin (TMPyP4), using differential scanning calorimetry, isothermal titration calorimetry, and circular dichroism spectroscopy. We examined three different 24-mer oligonucleotides, including the wild-type (WT) sequence found in the c-MYC P(1) promoter and two mutant G→T sequences that are known to fold into single 1:2:1 and 1:6:1 loop isomer quadruplexes. Biophysical experiments were performed on all three oligonucleotide sequences at two different ionic strengths (30 mM [K(+)] and 130 mM [K(+)]). Differential scanning calorimetry experiments demonstrated that the WT quadruplex consists of a mixture of at least two different folded conformers at both ionic strengths, whereas both mutant sequences exhibit a single two-state melting transition at both ionic strengths. Isothermal titration calorimetry experiments demonstrated that both mutant sequences bind 4 mols of TMPyP4 to 1 mol of DNA, in similarity to the WT sequence. The circular dichroism spectroscopy signatures for all three oligonucleotides at both ionic strengths are consistent with an intramolecular parallel stranded G-quadruplex structure, and no change in quadruplex structure is observed upon addition of saturating amounts of TMPyP4 (i.e., 4:1 TMPyP4/DNA).

  5. Use of Differential Scanning Calorimetry (DSC) in the Characterization of EPDM/PP Blends

    NASA Astrophysics Data System (ADS)

    Stelescu, Maria Daniela; Airinei, Anton; Grigoras, Cristian; Niculescu-Aron, Ileana-Gabriela

    2010-12-01

    New polyolefinic thermoplastic elastomers based on the ethylene-propylene-diene monomer (EPDM) and polypropylene (PP) containing an EPDM elastomer of the last generation (Nordel NDR 47130), obtained by polymerization in the gaseous phase with metallocene catalysis, were prepared and characterized. The melting and crystallization behavior of these blends was investigated by differential scanning calorimetry. It is observed that the melting temperature, crystallization temperature, and crystallinity degree increase with an increase of PP loading. The influence of the blend composition on the physico-mechanical characteristics was discussed using statistical processing of the experimental data. Two compatibilizing procedures were utilized to improve the physico-mechanical characteristics of the samples: an addition method using different compatibilizing agents and dynamical vulcanization with three types of crosslinking systems. Significant improvements of the tensile strength and tear strength were noted by dynamic crosslinking, and the best results were obtained using a crosslinking system based on phenolic resin and tin chloride.

  6. TG-DSC method applied to drying characteristics of areca inflorescence during drying

    NASA Astrophysics Data System (ADS)

    Song, Fei; Wang, Hui; Huang, Yulin; Zhang, Yufeng; Chen, Weijun; Zhao, Songlin; Zhang, Ming

    2017-10-01

    In this study, suitability of eight drying models available in literature on defining drying characteristics of areca inflorescence has been examined by non-linear regression analysis using the Statistic Computer Program. The coefficient of determination ( R 2 ) and the reduced chi-square (χ2) are used as indicators to evaluate the best suitable model. According to the results, the Verma et al. model gave the best results for explaining the drying characteristics of areca inflorescence. The drying process could be divided into three periods: rising rate, constant rate and the falling rate period. Fick's second law can describe the moisture transport during the food drying process that takes place in the falling rate period. The values of effective diffusivity during the drying of areca inflorescence ranged from 2.756 × 10-7 to 6.257 × 10-7 m2/s and the activation energy was tested for 35.535 kJ/mol. The heat requirement of areca inflorescence at 40-60 °C was calculated from 50.57 to 60.50 kJ/kg during the drying process.

  7. The effects of minor constituents on biodiesel cold flow properties: Differential scanning calorimetry (DSC) analyses

    USDA-ARS?s Scientific Manuscript database

    Biodiesel is an alternative diesel fuel made from vegetable oils, animal fats and other lipid feedstocks. Fuel properties and performance of biodiesel during cold weather are influenced by factors related to lipid feedstock as well as small concentrations of monoacylglycerols and other minor constit...

  8. Automated detection of arterial input function in DSC perfusion MRI in a stroke rat model

    NASA Astrophysics Data System (ADS)

    Yeh, M.-Y.; Lee, T.-H.; Yang, S.-T.; Kuo, H.-H.; Chyi, T.-K.; Liu, H.-L.

    2009-05-01

    Quantitative cerebral blood flow (CBF) estimation requires deconvolution of the tissue concentration time curves with an arterial input function (AIF). However, image-based determination of AIF in rodent is challenged due to limited spatial resolution. We evaluated the feasibility of quantitative analysis using automated AIF detection and compared the results with commonly applied semi-quantitative analysis. Permanent occlusion of bilateral or unilateral common carotid artery was used to induce cerebral ischemia in rats. The image using dynamic susceptibility contrast method was performed on a 3-T magnetic resonance scanner with a spin-echo echo-planar-image sequence (TR/TE = 700/80 ms, FOV = 41 mm, matrix = 64, 3 slices, SW = 2 mm), starting from 7 s prior to contrast injection (1.2 ml/kg) at four different time points. For quantitative analysis, CBF was calculated by the AIF which was obtained from 10 voxels with greatest contrast enhancement after deconvolution. For semi-quantitative analysis, relative CBF was estimated by the integral divided by the first moment of the relaxivity time curves. We observed if the AIFs obtained in the three different ROIs (whole brain, hemisphere without lesion and hemisphere with lesion) were similar, the CBF ratios (lesion/normal) between quantitative and semi-quantitative analyses might have a similar trend at different operative time points. If the AIFs were different, the CBF ratios might be different. We concluded that using local maximum one can define proper AIF without knowing the anatomical location of arteries in a stroke rat model.

  9. Two new species of the genus Vosmaeropsis Dendy, 1892 (Porifera, Calcarea), with comments on the distribution of V. sericata (Ridley, 1881) along the Southwestern Atlantic Ocean.

    PubMed

    Cavalcanti, Fernanda F; Bastos, Nilma; Lanna, Emilio

    2015-05-12

    Two new species of the genus Vosmaeropsis are described: V. recruta sp. nov. and V. complanatispinifera sp. nov., both from the Brazilian coast. These species possess arrow-shaped large diactines in their skeletons, which are being described for the first time in Vosmaeropsis. In addition, the latter species presents another remarkable character: the apical actines of its atrial tetractines is flattened and provided with spines. Vosmaeropsis complanastispinifera sp. nov. is being proposed based on the re-analysis of specimens that in the past were assigned to V. sericata. Thus, with the reallocation of these specimens to the newly described species, the current distribution range of V. sericata does not include the Brazilian northeastern coast. Vosmaeropsis now comprises 23 species. Most of them present an endemic pattern of distribution, but the genus is widely distributed in tropical and temperate regions around the world.

  10. Helminths from an introduced species (Tupinambis merianae), and two endemic species (Trachylepis atlantica and Amphisbaena ridley) from Fernando de Noronha Archipelago, Brazil.

    PubMed

    Ramalho, A C O; da Silva, R J; Schwartz, H O; Péres, A K

    2009-08-01

    The present study reports the occurrence of helminths in the introduced species Tupinambis merianae (tegu lizard), and in two endemic species Trachylepis atlantica (small lizard) and Amphisbaena ridleyi (two-head-snake lizard ), from Fernando de Noronha Archipelago, State of Pernambuco, Brazil. Nine species of helminths were found, mainly in the digestive tract and accessory organs, with the following prevalence (P) and mean infection intensity (MII). Tupinambis merianae: Diaphanocephalus galeatus (P = 96%, MII = 20.5), Spinicauda spinicauda (P = 100%, MII = 197.8), and Oochoristica sp.l (P = 20%, MII = 4.4). Trachylepis atlantica: Moaciria alvarengai (P = 20%, MII = 1.4), S. spinicauda (P = 92%, MII = 22.1), Mesocoelium monas (P = 4%, MII = 3.0), Platynosomum sp. (P = 8%, MII = 7.0), and Oochoristica sp.2 (P = 16%, MII = 1.25). Amphisbaena ridleyi: Aplectana albae (P = 96%, MII = 143.4), Thelandros alvarengai (P = 4%, MII = 1.0), Me. monas (P = 44%, MII = 2.8), Platynosomum sp. (P = 36%; MII = 13.8), and Oochoristica sp.2 (P = 48%; MII = 2.17). More than 80% of T. merianae were infected with 2, or more, helminth species. In Tr. atlantica, single-species infections were present in 50% of the specimens, but co-occurrence of 2 parasites was also high (41.7%). In A. ridleyi, multiple infections were more common, with up to 5 parasite species present. The helminth fauna observed allowed us to conclude that helminths can be carried together with their host when they colonize new geographic localities and that these introduced helminths can, in turn, colonize endemic, or native, hosts.

  11. 78 FR 13642 - Endangered Species; File No. 17506

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-28

    ... captures, green, loggerhead, hawksbill, Kemp's ridley, and leatherback sea turtles would be counted during... to take green (Chelonia mydas), loggerhead (Caretta caretta), hawksbill (Eretmochelys imbricata), Kemp's ridley (Lepidochelys kempii), and leatherback (Dermochelys coriaceae) sea turtles for...

  12. 76 FR 76950 - Endangered Species; File No. 16134

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-09

    ... permit to conduct research on leatherback, loggerhead, green, hawksbill, and Kemp's ridley sea turtles in... a permit to take green (Chelonia mydas), Kemp's ridley (Lepidochelys kempii), hawksbill (Eretmochelys imbricata), leatherback (Dermochelys coriacea), and loggerhead (Caretta caretta) sea turtles...

  13. 75 FR 22106 - Endangered Species; File No. 14510

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-27

    ... (Chelonia mydas), loggerhead (Caretta caretta), olive ridley (Lepidochelys olivacea), and leatherback..., inject tetracycline, and release up to: ten green, one olive ridley, and three loggerhead sea turtles taken in power plant entrainments; four green, one olive ridley, one loggerhead, and two leatherback...

  14. Calorimetric and thermomechanical properties of titanium-based orthodontic wires: DSC-DMA relationship to predict the elastic modulus.

    PubMed

    Laino, Giuliana; De Santis, Roberto; Gloria, Antonio; Russo, Teresa; Quintanilla, David Suárez; Laino, Alberto; Martina, Roberto; Nicolais, Luigi; Ambrosio, Luigi

    2012-03-01

    Orthodontic treatment is strongly dependent on the loads developed by metal wires, and the choice of an orthodontic archwire should be based on its mechanical performance. The desire of both orthodontists and engineers would be to predict the mechanical behavior of archwires. To this aim, Gum Metal (Toyota Central R&L Labs., Inc.), TMA (ORMCO), 35°C Copper NiTi (SDS ORMCO), Thermalloy Plus (Rocky Mountain), Nitinol SE (3M Unitek), and NiTi (SDS ORMCO) were tested according to dynamic mechanical analysis and differential scanning calorimetry. A model was also developed to predict the elastic modulus of superelastic wires. Results from experimental tests have highlighted that superelastic wires are very sensitive to temperature variations occurring in the oral environment, while the proposed model seems to be reliable to predict the Young's modulus allowing to correlate calorimetric and mechanical data. Furthermore, Gum Metal wire behaves as an elastic material with a very low Young's modulus, and it can be particularly useful for the initial stage of orthodontic treatments.

  15. Isothermal Time-Temperature-Precipitation Diagram for an Aluminum Alloy 6005A by In Situ DSC Experiments

    PubMed Central

    Milkereit, Benjamin; Giersberg, Lydia; Kessler, Olaf; Schick, Christoph

    2014-01-01

    Time-temperature-precipitation (TTP) diagrams deliver important material data, such as temperature and time ranges critical for precipitation during the quenching step of the age hardening procedure. Although the quenching step is continuous, isothermal TTP diagrams are often applied. Together with a so-called Quench Factor Analysis, they can be used to describe very different cooling paths. Typically, these diagrams are constructed based on mechanical properties or microstructures after an interrupted quenching, i.e., ex situ analyses. In recent years, an in situ calorimetric method to record continuous cooling precipitation diagrams of aluminum alloys has been developed to the application level by our group. This method has now been transferred to isothermal experiments, in which the whole heat treatment cycle was performed in a differential scanning calorimeter. The Al-Mg-Si-wrought alloy 6005A was investigated. Solution annealing at 540 °C and overcritical quenching to several temperatures between 450 °C and 250 °C were followed by isothermal soaking. Based on the heat flow curves during isothermal soaking, TTP diagrams were determined. An appropriate evaluation method has been developed. It was found that three different precipitation reactions in characteristic temperature intervals exist. Some of the low temperature reactions are not accessible in continuous cooling experiments and require isothermal studies. PMID:28788587

  16. Interfacial Water at Protein Surfaces: Wide-Line NMR and DSC Characterization of Hydration in Ubiquitin Solutions

    PubMed Central

    Tompa, Kálmán; Bánki, Péter; Bokor, Mónika; Kamasa, Pawel; Lasanda, György; Tompa, Péter

    2009-01-01

    Wide-line 1H-NMR and differential scanning calorimetry measurements were done in aqueous solutions and on lyophilized samples of human ubiquitin between −70°C and +45°C. The measured properties (size, thermal evolution, and wide-line NMR spectra) of the protein-water interfacial region are substantially different in the double-distilled and buffered-water solutions of ubiquitin. The characteristic transition in water mobility is identified as the melting of the nonfreezing/hydrate water. The amount of water in the low-temperature mobile fraction is 0.4 g/g protein for the pure water solution. The amount of mobile water is higher and its temperature dependence more pronounced for the buffered solution. The specific heat of the nonfreezing/hydrate water was evaluated using combined differential scanning calorimetry and NMR data. Considering the interfacial region as an independent phase, the values obtained are 5.0–5.8 J·g−1·K−1, and the magnitudes are higher than that of pure/bulk water (4.2 J·g−1·K−1). This unexpected discrepancy can only be resolved in principle by assuming that hydrate water is in tight H-bond coupling with the protein matrix. The specific heat for the system composed of the protein molecule and its hydration water is 2.3 J·g−1·K−1. It could be concluded that the protein ubiquitin and its hydrate layer behave as a highly interconnected single phase in a thermodynamic sense. PMID:19348762

  17. Heat Estimation from Infrared Measurement Compared to DSC for Austenite to R Phase Transformation in a NiTi Alloy

    NASA Astrophysics Data System (ADS)

    Delobelle, V.; Favier, D.; Louche, H.

    2013-06-01

    Heat source estimations from temperature field measurements deduced from infrared imaging are increasingly used to study thermo-mechanical coupling during materials' deformation. These estimations are based on approximations of the derivative terms with respect to time and space which are involved in the heat diffusion equation. This paper proposes a first experimental validation of this method by applying it to an experimental uniform air cooling of a NiTi Shape Memory Alloy thin plate. In the studied cooling temperate range, heat sources are due to Austenite to R phase transformation. Transformation temperatures, heat sources, and energies are estimated from infrared temperature measurements and compared successfully to differential scanning calorimetry results.

  18. DSC evaluation of extra virgin olive oil stability under accelerated oxidative test: effect of fatty acid composition and phenol contents.

    PubMed

    Cerretani, Lorenzo; Bendini, Alessandra; Rinaldi, Massimiliano; Paciulli, Maria; Vecchio, Stefano; Chiavaro, Emma

    2012-01-01

    Three extra virgin olive oils having different fatty acid compositions and total phenol contents were submitted to an accelerated storage test at 60°C for up to 21 weeks. Their oxidative status, evaluated by peroxide values and total phenolic content, was related to differential scanning calorimetry cooling profiles and thermal properties. Changes in crystallization profiles were consistent starting from 12 weeks for the two oil samples (B and C) that had a higher content of linoleic acid and medium/low amounts of phenols, respectively, whereas they became detectable at the end of the test for the remaining oil (sample A). Decrease of crystallization enthalpy and shift of transition towards lower temperature were also evident at 4 weeks of storage for samples B and C, whereas the same changes in the transition profile were noticeable at 12 weeks for sample A. Differential scanning calorimetry appears to be suitable for the discrimination of oxidative status of extra virgin olive oils with widely different fatty acid composition.

  19. GlidCop® DSC properties in the temperature range of 20-350°C

    NASA Astrophysics Data System (ADS)

    Solomon, Ronald R.; Troxell, Jack D.; Nadkarni, Anil V.

    1996-10-01

    GlidCop® AL-25 LOX-80 grade plates manufactured by processes relevant to ITER first wall copper alloy requirements were tested in the temperature range of 20-350°C. Plate manufacturing methods included hot isotatic pressing (HIP), extrusion (EXT), and extrusion followed by cross-rolling (EXT + XROLL). Tests that were performed included tensile, fracture toughness, impact toughness, and creep. The EXT + XROLL plate was found to have higher total elongation, reduction of area, and fracture toughness values than the EXT and HIP plates. All three processes had similar ultimate tensile and 0.2% yield strengths. The HIP material exhibited a lower creep rate than EXT + XROLL. The EXT and the EXT + XROLL plates had similar impact toughness values, which were higher than the HIP plate. Overall, the EXT + XROLL plate had the best combination of properties of the three processes examined.

  20. Assessment of a combined spin- and gradient-echo (SAGE) DSC-MRI method for preclinical neuroimaging.

    PubMed

    Stokes, Ashley M; Skinner, Jack T; Quarles, C Chad

    2014-12-01

    The goal of this study was to optimize and validate a combined spin- and gradient-echo (SAGE) sequence for dynamic susceptibility-contrast magnetic resonance imaging to obtain hemodynamic parameters in a preclinical setting. The SAGE EPI sequence was applied in phantoms and in vivo rat brain (normal, tumor, and stroke tissue). Partial and full Fourier encoding schemes were implemented and characterized. Maps of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), vessel size index (VSI), volume transfer constant (K(trans)), and volume fraction of the extravascular extracellular space (ve) were obtained. Partial Fourier encoding provided shortened echo times with acceptable signal-to-noise ratio and temporal stability, thus enabling reliable characterization of T2, T2(*) and T1 in both phantoms and rat brain. The hemodynamic parameters CBV, CBF, and MTT for gradient-echo and spin-echo contrast were determined in tumor and stroke; VSI, K(trans), and ve were also computed in tumor tissue. The SAGE EPI sequence allows the acquisition of multiple gradient- and spin-echoes, from which measures of perfusion, permeability, and vessel size can be obtained in a preclinical setting. Partial Fourier encoding can be used to minimize SAGE echo times and reliably quantify dynamic T2 and T2(*) changes. This acquisition provides a more comprehensive assessment of hemodynamic status in brain tissue with vascular and perfusion abnormalities.

  1. Exploration of Functionality of Low-Glycemic-Impact Sugars and Polyols using DSC, RVA, SRC, and Cookie Baking

    USDA-ARS?s Scientific Manuscript database

    Consumers’ growing interest in healthy cookies includes expectations for prebiotic nutritional benefits and low glycemic impact. The anti-plasticizing action of the high sucrose concentration in a cookie formula inhibits gluten development during dough mixing and starch gelatinization/pasting durin...

  2. Comparison of BOLD cerebrovascular reactivity mapping and DSC MR perfusion imaging for prediction of neurovascular uncoupling potential in brain tumors.

    PubMed

    Pillai, Jay J; Zacà, Domenico

    2012-08-01

    The coupling mechanism between neuronal firing and cerebrovascular dilatation can be significantly compromised in cerebral diseases, making it difficult to identify eloquent cortical areas near or within resectable lesions by using Blood Oxygen Level Dependent (BOLD) fMRI. Several metabolic and vascular factors have been considered to account for this lesion-induced neurovascular uncoupling (NVU), but no imaging gold standard exists currently for the detection of NVU. However, it is critical in clinical fMRI studies to evaluate the risk of NVU because the presence of NVU may result in false negative activation that may result in inadvertent resection of eloquent cortex, resulting in permanent postoperative neurologic deficits. Although NVU results from a disruption of one or more components of a complex cellular and chemical neurovascular coupling cascade (NCC) MR imaging is only able to evaluate the final step in this NCC involving the ultimate cerebrovascular response. Since anything that impairs cerebrovascular reactivity (CVR) will necessarily result in NVU, regardless of its effect more proximally along the NCC, we can consider mapping of CVR as a surrogate marker of NVU potential. We hypothesized that BOLD breath-hold (BH) CVR mapping can serve as a better marker of NVU potential than T2* Dynamic Susceptibility Contrast gadolinium perfusion MR imaging, because the latter is known to only reflect NVU risk associated with high grade gliomas by determining elevated relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF) related to tumor angiogenesis. However, since low and intermediate grade gliomas are not associated with such tumoral hyperperfusion, BOLD BH CVR mapping may be able to detect such NVU potential even in lower grade gliomas without angiogenesis, which is the hallmark of glioblastomas. However, it is also known that glioblastomas are associated with variable NVU, since angiogenesis may not always result in NVU. Perfusion metrics obtained by T2* gadolinium perfusion MR imaging were compared to BOLD percentage signal change on BH CVR maps in a group of 19 patients with intracranial brain tumors of different nature and grade. Single pixel maximum rCBV and rCBF within holotumoral regions of interest (i.e., "ipsilesional" ROIs) were normalized to contralateral hemispheric homologous (i.e., "contralesional") normal tissue. Furthermore, percentage signal change on BH CVR maps within ipsilesional ROIs were normalized to the percentage signal change within contralesional homologous ROIs. Inverse linear correlation was found between normalized rCBF (r(flow)) or rCBV (r(vol)) and normalized CVR percentage signal change (r(CVR)) in grade IV lesions. In the grade III lesions a less steep inverse linear trend was seen that did not reach statistical significance, whereas no correlation at all was seen in the grade II group. Statistically significant difference was present for r(flow) and r(vol) between the grade II and IV groups and between the grade III and IV groups but not for r(CVR). The r(CVR) was significantly lower than 1 in every group. Our results demonstrate that while T2*MR perfusion maps and CVR maps are both adequate to map tumoral regions at risk of NVU in high grade gliomas, CVR maps can detect areas of decreased CVR also in low and intermediate grade gliomas where NVU may be caused by factors other than tumor neovascularity alone. Comparison of areas of abnormally decreased regional CVR with areas of absent BOLD task-based activation in expected eloquent cortical regions infiltrated by or adjacent to the tumors revealed overall 95% concordance, thus confirming the capability of BH CVR mapping to effectively demonstrate areas of NVU. ed by factors other than tumor neovascularity alone. Comparison of areas of abnormally decreased regional CVR with areas of absent BOLD task-based activation in expected eloquent cortical regions infiltrated by or adjacent to the tumors revealed overall 95% concordance, thus confirming the capability of BH CVR mapping to effectively demonstrate areas of NVU.

  3. Thermal Properties of Extruded Injection-Molded Polycaprolactone/Gluten Bioblends Characterized by TGA, DSC, SEM and Infrared Photoacoustic Spectroscopy

    USDA-ARS?s Scientific Manuscript database

    In order to determine the degree of compatibility between Polycaprolactone resin (PCL) and vital wheat gluten (VG), PCL was compounded with VG at 90:10, 80:20, 70:30, 60:40, 50:50, and 30:70. The composites were blended by extrusion followed by injection molding. Thermal, morphological, and struct...

  4. Molecular weight dependence of the intrinsic size effect on Tg in AAO template-supported polymer nanorods: A DSC study

    NASA Astrophysics Data System (ADS)

    Askar, Shadid; Wei, Tong; Tan, Anthony W.; Torkelson, John M.

    2017-05-01

    Many studies have established a major effect of nanoscale confinement on the glass transition temperature (Tg) of polystyrene (PS), most commonly in thin films with one or two free surfaces. Here, we characterize smaller yet significant intrinsic size effects (in the absence of free surfaces or significant attractive polymer-substrate interactions) on the Tg and fragility of PS. Melt infiltration of various molecular weights (MWs) of PS into anodic aluminum oxide (AAO) templates is used to create nanorods supported on AAO with rod diameter (d) ranging from 24 to 210 nm. The Tg (both as Tg,onset and fictive temperature) and fragility values are characterized by differential scanning calorimetry. No intrinsic size effect is observed for 30 kg/mol PS in template-supported nanorods with d = 24 nm. However, effects on Tg are present for PS nanorods with Mn and Mw ≥ ˜175 kg/mol, with effects increasing in magnitude with increasing MW. For example, in 24-nm-diameter template-supported nanorods, Tg, rod - Tg, bulk = -2.0 to -2.5 °C for PS with Mn = 175 kg/mol and Mw = 182 kg/mol, and Tg, rod - Tg, bulk = ˜-8 °C for PS with Mn = 929 kg/mol and Mw = 1420 kg/mol. In general, reductions in Tg occur when d ≤ ˜2Rg, where Rg is the bulk polymer radius of gyration. Thus, intrinsic size effects are significant when the rod diameter is smaller than the diameter (2Rg) associated with the spherical volume pervaded by coils in bulk. We hypothesize that the Tg reduction occurs when chain segment packing frustration is sufficiently perturbed by confinement in the nanorods. This explanation is supported by observed reductions in fragility with the increasing extent of confinement. We also explain why these small intrinsic size effects do not contradict reports that the Tg-confinement effect in supported PS films with one free surface exhibits little or no MW dependence.

  5. Thermal behavior of native and hydrophobized wheat gluten, gliadin and glutenin-rich fractions by modulated DSC.

    PubMed

    Micard, V; Guilbert, S

    2000-06-13

    The glass transition temperature (T(g)) of hydrophobized and native wheat gluten and its protein fractions, with water mass fraction from 0 to 0.2, was studied using modulated differential scanning calorimetry. The T(g) values of unplasticized products were approximately 175 degrees C whatever the treatment (hydrophobization) or the fraction tested, except for the gliadin-rich fraction (162 degrees C). Experimental change in heat capacity at the glass transition (DeltaC(p)) ranged from 0.32 to 0. 50 J/g/ degrees C depending on the gluten fractions. The Gordon-Taylor fit of T(g) evolution as a function of water content showed that glutenin-rich fractions were more sensitive to water plasticization than the gliadin-rich fraction. The Kwei equation gave better fit to experimental data and demonstrated that the water plasticization of gluten and its fractions is influenced by secondary interactions. However, the application of the Couchman-Karasz equation without fitting predicts satisfactorily the plasticization of gluten proteins by water.

  6. Molecular weight dependence of the intrinsic size effect on Tg in AAO template-supported polymer nanorods: A DSC study.

    PubMed

    Askar, Shadid; Wei, Tong; Tan, Anthony W; Torkelson, John M

    2017-05-28

    Many studies have established a major effect of nanoscale confinement on the glass transition temperature (Tg) of polystyrene (PS), most commonly in thin films with one or two free surfaces. Here, we characterize smaller yet significant intrinsic size effects (in the absence of free surfaces or significant attractive polymer-substrate interactions) on the Tg and fragility of PS. Melt infiltration of various molecular weights (MWs) of PS into anodic aluminum oxide (AAO) templates is used to create nanorods supported on AAO with rod diameter (d) ranging from 24 to 210 nm. The Tg (both as Tg,onset and fictive temperature) and fragility values are characterized by differential scanning calorimetry. No intrinsic size effect is observed for 30 kg/mol PS in template-supported nanorods with d = 24 nm. However, effects on Tg are present for PS nanorods with Mn and Mw ≥ ∼175 kg/mol, with effects increasing in magnitude with increasing MW. For example, in 24-nm-diameter template-supported nanorods, Tg, rod - Tg, bulk = -2.0 to -2.5 °C for PS with Mn = 175 kg/mol and Mw = 182 kg/mol, and Tg, rod - Tg, bulk = ∼-8 °C for PS with Mn = 929 kg/mol and Mw = 1420 kg/mol. In general, reductions in Tg occur when d ≤ ∼2Rg, where Rg is the bulk polymer radius of gyration. Thus, intrinsic size effects are significant when the rod diameter is smaller than the diameter (2Rg) associated with the spherical volume pervaded by coils in bulk. We hypothesize that the Tg reduction occurs when chain segment packing frustration is sufficiently perturbed by confinement in the nanorods. This explanation is supported by observed reductions in fragility with the increasing extent of confinement. We also explain why these small intrinsic size effects do not contradict reports that the Tg-confinement effect in supported PS films with one free surface exhibits little or no MW dependence.

  7. Hilda Mary Woods MBE, DSc, LRAM, FSS (1892–1971): reflections on a Fellow of the Royal Statistical Society

    PubMed Central

    Farewell, Vern; Johnson, Tony; Gear, Rosemary

    2012-01-01

    We have previously described the content of a text by Woods and Russell, An Introduction to Medical Statistics, compared it with Principles of Medical Statistics by Hill and set both volumes against the background of vital statistics up until 1937. The two books mark a watershed in the history of medical statistics. Very little has been recorded about the life and career of the first author of the earlier textbook, who was a Fellow of the Royal Statistical Society for at least 25 years, an omission which we can now rectify with this paper. We describe her education, entry into medical statistics, relationship with Major Greenwood and her subsequent career and life in Ceylon, Kenya, Australia, England and South Africa. PMID:22973076

  8. Lindon J. Eaves, Ph.D., M.A. (Oxon), D.Sc. Theory-model-data.

    PubMed

    Maes, Hermine H M; Hatemi, Peter K; Neale, Michael C

    2014-05-01

    We begin this special issue by providing a glimpse into the career of Dr. Lindon J. Eaves, from the perspectives of a student, postdoc, instructor, assistant to associate and full professor over the last 20 odd years. We focus primarily on Lindon's contributions to methodological issues and research designs to address them, in particular those related to models for extended twin-family designs, for the development of adolescent behavior, for genotype-environment covariation and interaction, and their application to the Virginia 30,000 and the Virginia Twin Study of Adolescent Behavioral Development. We then introduce the collection of papers in this special festschrift issue of Behavior Genetics, celebrating Dr. Eaves achievements over the last 40 years.

  9. Interaction of local and general anaesthetics with liposomal membrane models: a QCM-D and DSC study.

    PubMed

    Paiva, José Gabriel; Paradiso, Patrizia; Serro, Ana Paula; Fernandes, Anabela; Saramago, Benilde

    2012-06-15

    The behaviour of four local anaesthetics (lidocaine, levobupivacaine, ropivacaine and tetracaine) and one general anaesthetic (propofol) is compared when interacting with two types of model membranes: supported layers of liposomes and liposomes in solution. Several liposomal compositions were tested: dimyristoylphosphatidylcholine (DMPC), binary mixtures of DMPC with cholesterol (CHOL), and ternary mixtures of dipalmitoylphosphatidylcholine (DPPC), DMPC, and CHOL. A quartz crystal microbalance with dissipation, QCM-D, was used to assess changes in the properties of supported layers of liposomes. The effect of the anaesthetics on the phase behaviour of the liposomes in suspension was determined by differential scanning calorimetry. Both techniques show that all anaesthetics have a fluidizing effect on the model membranes but, apparently, the solid supported liposomes are less affected by the anaesthetics than the liposomes in solution. Although the different anaesthetics were compared at different concentrations, tetracaine and propofol seem to induce the strongest perturbation on the liposome membrane. The resistance of the liposomes to the anaesthetic action was found to increase with the presence of cholesterol, while adding DPPC to the binary mixture DMPC+CHOL does not change its behaviour. The novelty of the present work resides upon three points: (1) the use of supported layers of liposomes as model membranes to study interactions with anaesthetics; (2) application of QCM-D to assess changes of the adsorbed liposomes; (3) a comparison of the effect of local and general anaesthetics interacting with various model membranes in similar experimental conditions.

  10. Parametric modeling of DSC-MRI data with stochastic filtration and optimal input design versus non-parametric modeling.

    PubMed

    Kalicka, Renata; Pietrenko-Dabrowska, Anna

    2007-03-01

    In the paper MRI measurements are used for assessment of brain tissue perfusion and other features and functions of the brain (cerebral blood flow - CBF, cerebral blood volume - CBV, mean transit time - MTT). Perfusion is an important indicator of tissue viability and functioning as in pathological tissue blood flow, vascular and tissue structure are altered with respect to normal tissue. MRI enables diagnosing diseases at an early stage of their course. The parametric and non-parametric approaches to the identification of MRI models are presented and compared. The non-parametric modeling adopts gamma variate functions. The parametric three-compartmental catenary model, based on the general kinetic model, is also proposed. The parameters of the models are estimated on the basis of experimental data. The goodness of fit of the gamma variate and the three-compartmental models to the data and the accuracy of the parameter estimates are compared. Kalman filtering, smoothing the measurements, was adopted to improve the estimate accuracy of the parametric model. Parametric modeling gives a better fit and better parameter estimates than non-parametric and allows an insight into the functioning of the system. To improve the accuracy optimal experiment design related to the input signal was performed.

  11. Once a physicist: Tony Hey

    NASA Astrophysics Data System (ADS)

    2008-01-01

    Why did you originally choose to study physics? I was really interested in science at school, and I also read a couple of fascinating popular-science books about quantum mechanics and special relativity. My interest in these topics made me decide to study physics at Oxford University. Straight after I graduated in 1967 I did a theoretical-physics DPhil, also at Oxford.

  12. National Dam Inspection Program. Broomalls Dam (NDS I.D. Number PA 00349, DER I.D. Number 23-9), Delaware River Basin, Tributary to Ridley Creek, Delaware County, Pennsylvania. Phase I Inspection Report,

    DTIC Science & Technology

    1980-03-01

    soil and settled. The culvert buckled at the point where it bent. Reportedly, this has been a result of surface runoff from Third Street, flowing over...at its * outlet and had a column of ice between the culvert outlet and embankment toe. There was no supporting soil for at least 16 *feet behind the...outlet. Ice was visible where the culvert *entered the soil . The middle culvert has pulled apart at a joint and is held together by a band. Evidence of

  13. 76 FR 77781 - Endangered Species; File No. 15802

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ... authorization to capture green (Chelonia mydas), hawksbill (Eretmochelys imbricata), Kemp's ridley (Lepidochelys kempii), leatherback (Dermochelys coriacea), and loggerhead (Caretta caretta) sea turtles. Sea...

  14. The Community-based Whole Magnetosphere Model

    DTIC Science & Technology

    2011-11-15

    Ground magnetic field perturbations, Space Weather, 9, S02004, doi:10.1029/2010SW000600, 2011. 8 . Yiğit, E., A.J. Ridley, Effects of high- latitude...doi:10.1029/2009JA014596, 2010. 17. Welling, D. T., and A. J. Ridley, Vali- dation of SWMF magnetic field and plasma, Space Weather, 8 , S03002, doi... interplanetary magnetic fields , Ann. Geophys., 25, 533, 2007. CWMM-17 Ridley CWMM Final Report 45. A.J. Ridley, Effects of seasonal changes in the ionospheric

  15. Wide-line NMR and DSC studies on intrinsically disordered p53 transactivation domain and its helically pre-structured segment

    PubMed Central

    Tompa, Peter; Han, Kyou-Hoon; Bokor, Mónika; Kamasa, Pawel; Tantos, Ágnes; Fritz, Beáta; Kim, Do-Hyoung; Lee, Chewook; Verebélyi, Tamás; Tompa, Kálmán

    2016-01-01

    Wide-line 1H NMR intensity and differential scanning calorimetry measurements were carried out on the intrinsically disordered 73-residue full transactivation domain (TAD) of the p53 tumor suppressor protein and two peptides: one a wild type p53 TAD peptide with a helix pre-structuring property, and a mutant peptide with a disabled helix-forming propensity. Measurements were carried out in order to characterize their water and ion binding characteristics. By quantifying the number of hydrate water molecules, we provide a microscopic description for the interactions of water with a wild-type p53 TAD and two p53 TAD peptides. The results provide direct evidence that intrinsically disordered proteins (IDPs) and a less structured peptide not only have a higher hydration capacity than globular proteins, but are also able to bind a larger amount of charged solute ions. [BMB Reports 2016; 49(9): 497-501] PMID:27418282

  16. Infrared spectroscopy as a tool to characterise starch ordered structure--a joint FTIR-ATR, NMR, XRD and DSC study.

    PubMed

    Warren, Frederick J; Gidley, Michael J; Flanagan, Bernadine M

    2016-03-30

    Starch has a heterogeneous, semi-crystalline granular structure and the degree of ordered structure can affect its behaviour in foods and bioplastics. A range of methodologies are employed to study starch structure; differential scanning calorimetry, (13)C nuclear magnetic resonance, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR). Despite the appeal of FTIR as a rapid, non-destructive methodology, there is currently no systematically defined quantitative relationship between FTIR spectral features and other starch structural measures. Here, we subject 61 starch samples to structural analysis, and systematically correlate FTIR spectra with other measures of starch structure. A hydration dependent peak position shift in the FTIR spectra of starch is observed, resulting from increased molecular order, but with complex, non-linear behaviour. We demonstrate that FTIR is a tool that can quantitatively probe short range interactions in starch structure. However, the assumptions of linear relationships between starch ordered structure and peak ratios are overly simplistic.

  17. Photodegradation assessment of ciprofloxacin, moxifloxacin, norfloxacin and ofloxacin in the presence of excipients from tablets by UPLC-MS/MS and DSC

    PubMed Central

    2013-01-01

    Background Ciprofloxacin (CIP), moxifloxacin (MOX), norfloxacin (NOR) and ofloxacin (OFL), are the antibacterial synthetic drugs, belonging to the fluoroquinolones group. Fluoroquinolones are compounds susceptible to photodegradation process, which may lead to reduction of their antibacterial activity and to induce phototoxicity as a side effect. This paper describes a simple, sensitive UPLC-MS/MS method for the determination of CIP, MOX, NOR and OFL in the presence of photodegradation products. Results Chromatographic separations were carried out using the Acquity UPLC BEH C18 column; (2.1 × 100 mm, 1.7 μm particle size). The column was maintained at 40°C, and the following gradient was used: 0 min, 95% of eluent A and 5% of eluent B; 10 min, 0% of eluent A and 100% of eluent B, at a flow rate of 0.3 mL min-1. Eluent A: 0.1% (v/v) formic acid in water; eluent B: 0.1% (v/v) formic acid in acetonitrile. The method was validated and all the validation parameters were in the ranges acceptable by the guidelines for analytical method validation. The photodegradation of examined fluoroquinolones in solid phase in the presence of excipients followed kinetic of the first order reaction and depended upon the type of analyzed drugs and coexisting substances. Photodegradation process of analyzed drugs was confirmed by differential scanning calorimetry. In addition, the identification of degradation products was carried out by mass spectrometry. Conclusion The developed UPLC-MS/MS method enables the determination of CIP, MOX, NOR and OFL in the presence of photodegradation products and identification of photodegradation products. PMID:23899303

  18. Analysis of Two Methods for Characterization of Flame Resistant Military Fabrics and Commercial Textile Fibers: Simultaneous DSC-TGA and Pyrolysis GCMS

    DTIC Science & Technology

    2014-04-04

    Aramid Kevlar® E. I. DuPont de Nemours & Co. Meta-Aramid Nomex® E. I. DuPont de Nemours & Co. Para-Aramid Twaron® Teijin Limited Polybenzimidazole PBI ... PBI ® Performance Products, Inc. 5 3 Methods 3.1 Thermal Analysis - SDT The SDT instrument used in this experiment was manufactured by TA...427 °C PBI ® 30% 475 °C 424 °C 477 °C Air Nylon 6,6 98 % 452 °C 420 °C 439 °C FR-Cotton 82 % 299 °C 285 °C 334 °C Untreated Rayon 100% 324 °C

  19. Antimycobacterial, antimicrobial activity, experimental (FT-IR, FT-Raman, NMR, UV-Vis, DSC) and DFT (transition state, chemical reactivity, NBO, NLO).

    PubMed

    Rawat, Poonam; Singh, R N; Ranjan, Alok; Ahmad, Sartaj; Saxena, Rajat

    2017-02-11

    As part of a study of pyrrole hydrazone, we have investigated quantum chemical calculations, molecular geometry, relative energy, vibrational properties and antimycobacterial/antimicrobial activity of pyrrole-2-carboxaldehyde isonicotinyl hydrazone (PCINH), by applying the density functional theory (DFT) and Hartree Fock (HF). Good reproduction of experimental values is obtained and with small percentage error in majority of the cases in comparison to theoretical result (DFT). The experimental FT-IR and Raman wavenumbers were compared with the respective theoretical values obtained from DFT calculations and found to agree well. In crystal structure studies the hydrated PCINH (syn-syn conformer) shows different conformation than from anhydrous form (syn-anti conformer). The rotational barrier between syn-syn and syn-anti conformers of PCINH is 12.7kcal/mol in the gas phase. In this work, use of FT-IR, FT-Raman, (1)H NMR, (13)C NMR and UV-Vis spectroscopies has been made for full characterization of PCINH. A detailed interpretation of the vibrational spectrum was carried out with the aid of normal coordinate analysis using single scaling factor. Our results support the hydrogen bonding pattern proposed by reported crystalline structure. The calculated nature of electronic transitions within molecule found to be π→π*. The electronic descriptors study indicates that PCINH can be used as robust synthon for synthesis of new heterocyclic compounds. The first static hyperpolarizability (β0) of PCINH is calculated as 33.89×10(-30)esu, (gas phase); 68.79×10(-30) (CHCl3), esu; 76.76×10(-30)esu (CH2Cl2), 85.16×10(-30)esu (DMSO). The solvent induced effects on the first static hyperpolarizability were studied and found to increase as dielectric constants of the solvents increases. Investigated molecule shows better NLO value than Para nitroaniline (PNA). The compound PCINH shows good antifungal and antibacterial activity against Aspergillus niger and gram-positive bacteria Bacillus subtilis, respectively. The compound also shows good antituberculosis activity against Mycobacterium tuberculosis H37Rv using the microplate alamar blue assay (MABA).

  20. Thermal: Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Polarized Microscopy Instrumentation for the Analysis of Field-Controlled Anisotropic Nanomaterials

    DTIC Science & Technology

    2014-11-14

    figure 1.2.1, right). The discovery TGA furnace design employs a silicon carbide ( SiC ) inner chamber. Four halogen lamps surrounded by a water...amplification,(13, 17) self-phase modulation (18, 19), and new nonlinear phenomena such as the nonlinear optical mirror ,(20) and the mirrorless optical

  1. A DSC investigation on the influence of gemini surfactant stereochemistry on the organization of lipoplexes and on their interaction with model membranes.

    PubMed

    Aleandri, S; Bonicelli, M G; Giansanti, L; Giuliani, C; Ierino, M; Mancini, G; Martino, A; Scipioni, A

    2012-12-01

    Previous investigations showed that the extent of DNA condensation and the efficiency in the transfection of liposomes formulated with 1,2-dimyristoyl-sn-glycero-phosphocholine and cationic stereomeric gemini surfactants depend heavily on the stereochemistry of the gemini. The influence of the stereochemistry on the interaction of lipoplexes with zwitterionic and anionic cell membrane models was investigated by differential scanning calorimetry to rationalize their different biological behavior. Further, the thermotropic behavior of the corresponding liposomes and of the spontaneous self-assemblies of gemini surfactants in the presence and in the absence of DNA was evaluated to correlate the physicochemical properties of lipoplexes and the stereochemistry of the cationic component. The obtained results show that the stereochemistry of the gemini surfactant controls lipoplexes organization and their mode and kinetic of interaction with different cell membrane models.

  2. Melting, crystallization and storage stability of virgin coconut oil and its blends by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR).

    PubMed

    Srivastava, Yashi; Semwal, Anil Dutt; Sajeevkumar, Vallayil Appukuttan; Sharma, G K

    2017-01-01

    The blends were prepared of virgin coconut oil with refined soyabean oil (VCO-RSOY) and refined safflower oil (VCO-RSAFF). Blending with VCO improved the fatty acid composition which increased the shelf stability of 20:80 VCO-RSOY and VCO-RSAFF up to 12 months in different packaging systems such as low density polyethylene, linear low density polyethylene, metalized polyester pouches, polyethylene teteraphthalate, high density polyethylene (HDPE), Amber HDPE bottle. The specific spectral regions of FTIR proved to be very useful for the determination of adulteration as well as for the study of oxidation process. Band shifts observed at 3008, 1652, 1397, 1097, 912 and 845 cm(-1) have been used to differentiate RSAFF from VCO. VCO spectrums did not have these chemical shifts. Further the spectrum of RSOY showed same band shifts as RSAFF except 1652, 1397, 869.6 and 845 cm(-1). Differential Scanning Calorimetry provided useful information regarding the nature of thermodynamic changes related to physical state of vegetable oil. The physical state changes included melting and crystallization events which require the intake and release of energy.

  3. DSC (Differential Scanning Calorimetry) and High Pressure Conductivity and Electrical Relaxation Measurements in PPO (Poly(Propylene Oxide) and PPO Complexed with Lithium Salts.

    DTIC Science & Technology

    1985-09-01

    Laboratories,; Inc. Electrochemical Power Sources Division 111 Downey Street Crane, Indiana 47522 Norwood, Massachusetts 02062 S. Ruby Dr. Aaron Wold DOE...Lesser Blum Dr. Donald Sandstrom - Department of Physics Boeing Aerospace Co. " University of Puerto Rico P.O. Box 3999 Rio Piedras , Puerto Rico 00931

  4. Characterization of the evolution of the volume fraction of precipitates in aged AlMgSiCu alloys using DSC technique

    SciTech Connect

    Esmaeili, Shahrzad . E-mail: shahrzad@mecheng1.uwaterloo.ca; Lloyd, David J.

    2005-11-15

    Differential scanning calorimetry is used to quantify the evolution of the volume fraction of precipitates during age hardening in AlMgSiCu alloys. The calorimetry tests are run on alloy samples after aging for various times at 180 deg. C and the change in the collective heat effects from the major precipitation and dissolution processes in each run are used to determine the precipitation state of the samples. The method is implemented on alloys with various thermal histories prior to artificial aging, including commercial pre-aging histories. The estimated values for the relative volume fraction of precipitates are compared with the results from a newly developed analytical method using isothermal calorimetry and a related quantitative transmission electron microscopy work. Excellent agreement is obtained between the results from various methods.

  5. Phase behavior in blends of ethylene oxide-propylene oxide copolymer and poly(ether sulfone) studied by modulated-temperature DSC and NMR relaxometry.

    PubMed

    Van Lokeren, Luk; Gotzen, Nicolaas-Alexander; Pieters, Ronny; Van Assche, Guy; Biesemans, Monique; Willem, Rudolph; Van Mele, Bruno

    2009-01-01

    The state diagram of a blend consisting of a copolymer containing ethylene oxide and propylene oxide, P(EO-ran-PO), and poly(ether sulfone), PES, is constructed by using modulated-temperature differential scanning calorimetry (MTDSC), T(2) NMR relaxometry, and light scattering. The apparent heat capacity signal in MTDSC is used for the characterization of polymer miscibility and morphology development. T(2) NMR relaxometry is used to detect the onset of phase separation, which is in good agreement with the onset of phase separation in the apparent heat capacity from MTDSC and the cloud-point temperature as determined from light scattering. The coexistence curve can be constructed from T(2) values at various temperatures by using a few blends with well-chosen compositions. These T(2) values also allow the detection of the boundary between the demixing zones with and without interference of partial vitrification and are in good agreement with stepwise quasi-isothermal MTDSC heat capacity measurements. Important interphases are detected in the heterogeneous P(EO-ran-PO)/PES blends.

  6. T1- and T2*-dominant extravasation correction in DSC-MRI: Part II—predicting patient outcome after a single dose of cediranib in recurrent glioblastoma patients

    PubMed Central

    Emblem, Kyrre E; Bjornerud, Atle; Mouridsen, Kim; Borra, Ronald J H; Batchelor, Tracy T; Jain, Rakesh K; Sorensen, A Gregory

    2011-01-01

    A ‘vascular normalization index' (VNI) based on the changes in the magnetic resonance imaging (MRI) parameters Ktrans and cerebral blood volume (CBV), combined with blood sampling, has been shown to correlate with patient outcome in recurrent glioblastoma after a single dose of antiangiogenic therapy. Here, by applying a novel contrast agent extravasation correction method insensitive to variations in tissue mean transit time, we show that a similar VNI parameter can be derived from a single dynamic susceptibility contrast MR acquisition rather than the three parameters shown previously. Our results show that this new VNI parameter, which combines changes in tumoral CBV and an apparent transfer constant from our leakage correction method, may provide prognostic information in an even simpler manner than prior efforts. PMID:21505476

  7. Copolymers sensitive to temperature and pH in water and in water+oil mixtures: A DSC, ITC and volumetric study.

    PubMed

    De Lisi, Rosario; Giammona, Gabriele; Lazzara, Giuseppe; Milioto, Stefana

    2011-02-15

    Block copolymer micelles are receiving an increasing interest because of the variety of structures and the possibilities to tune them by changing external and internal parameters achieving the desired properties for a specific purpose. We have investigated the acid/base behavior, self-assembling and solubilization ability towards polar oils of star-like copolymers named Tetronics. They are composed of branched four-arms each one consisting of two blocks made of EO and PO units linked to the diethylenediamine group, which confers pH response ability. The copolymers T1107 and T90R4 were studied with a sequential and reverse architecture. The thermodynamics of the acid/base equilibrium was studied by ITC. The aggregation of T1107 in water was analyzed as functions of pH, composition and temperature. The enhanced oil solubilization in the aqueous T1107 aggregates was widely investigated highlighting the role of the oil structure, composition, temperature and pH. As a general result, the oil induces the copolymer aggregation and the solubilization power of micelles is tunable by changing the pH. Efforts have been devoted to model the calorimetric data in order to achieve the thermodynamic properties of the involved process. Finally, we showed that the Tetronic micelles are more promising than the conventional surfactants micelles because of the larger solubilization power and flexibility of the macromolecular system.

  8. Surfactant softening of plant leaf cuticle model wax--a Differential Scanning Calorimetry (DSC) and Quartz Crystal Microbalance with Dissipation (QCM-D) study.

    PubMed

    Fagerström, Anton; Kocherbitov, Vitaly; Westbye, Peter; Bergström, Karin; Arnebrant, Thomas; Engblom, Johan

    2014-07-15

    The aim was to quantify the softening effect that two surfactants (C10EO7 and C8G1.6) have on a plant leaf cuticle model wax. Effects on the thermotropic phase behavior and fluidity of the wax (C22H45OH/C32H66/H2O) were determined. The model wax is crystalline at ambient conditions, yet it is clearly softened by the surfactants. Both surfactants decreased the transition temperatures in the wax and the G″/G' ratio of the wax film increased in irreversible steps following surfactant exposure. C10EO7 has a stronger fluidizing effect than C8G1.6 due to stronger interaction with the hydrophobic waxes. Intracuticular waxes (IW) comprise both crystalline and amorphous domains and it has previously been proposed that the fluidizing effects of surfactants are due to interactions with the amorphous parts. New data suggests that this may be a simplification. Surfactants may also absorb in crevices between crystalline domains. This causes an irreversible effect and a softer cuticle wax.

  9. Thermal effects in guest-host systems: [Zn2 (bdc)(S-lac)(dmf)]•PhEtOH: A DSC and NMR study.

    PubMed

    Kozlova, Svetlana G; Pishchur, Denis P; Gallyamov, Marsel R

    2017-03-29

    Differential scanning calorimetry and nuclear magnetic resonance were used to investigate thermal effects in the guest-host systems where homochiral metal-organic sorbent [Zn2 (bdc)(S-lac)(dmf)] is considered as a host while 1-phenylethanol enantiomers and their racemic mixture serve as guest molecules. A maximum energy gain from the guest-host interaction was observed in the system with the racemic mixture. The effect of host-guest recognition was revealed for the case of the host and guest having a similar type of chirality in the presence of antipode guest molecules.

  10. Differential Scanning Calorimetry Techniques: Applications in Biology and Nanoscience

    PubMed Central

    Gill, Pooria; Moghadam, Tahereh Tohidi; Ranjbar, Bijan

    2010-01-01

    This paper reviews the best-known differential scanning calorimetries (DSCs), such as conventional DSC, microelectromechanical systems-DSC, infrared-heated DSC, modulated-temperature DSC, gas flow-modulated DSC, parallel-nano DSC, pressure perturbation calorimetry, self-reference DSC, and high-performance DSC. Also, we describe here the most extensive applications of DSC in biology and nanoscience. PMID:21119929

  11. Differential scanning calorimetry techniques: applications in biology and nanoscience.

    PubMed

    Gill, Pooria; Moghadam, Tahereh Tohidi; Ranjbar, Bijan

    2010-12-01

    This paper reviews the best-known differential scanning calorimetries (DSCs), such as conventional DSC, microelectromechanical systems-DSC, infrared-heated DSC, modulated-temperature DSC, gas flow-modulated DSC, parallel-nano DSC, pressure perturbation calorimetry, self-reference DSC, and high-performance DSC. Also, we describe here the most extensive applications of DSC in biology and nanoscience.

  12. 77 FR 68809 - Endangered Species; Receipt of Applications for Permit

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-16

    ... permit to introduce from the high seas samples and/or whole carcasses of green sea turtle (Chelonia mydas), leatherback sea turtle (Dermochelys coriacea), hawksbill sea turtle (Eretmochelys imbricata), olive ridley sea turtle (Lepidochelys olivacea), Kemp's ridley sea turtle (Lepidochelys kempii), and...

  13. 75 FR 61133 - Marine Mammals and Endangered Species; File Nos. 808-1735, 14233, 14506, 14603, and 14726

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-04

    ... research on green, hawksbill, Kemp's ridley, loggerhead, and leatherback sea turtles had been submitted by... ridley, hawksbill, and leatherback sea turtles. A subset of green sea turtles may have a transmitter... amendment to conduct research ] on marine mammals or sea turtles. See SUPPLEMENTARY INFORMATION...

  14. 76 FR 4635 - Endangered Species; File No. 15552

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-26

    ..., loggerhead, hawksbill, leatherback, Kemp's ridley, olive ridley, and unidentified hardshell sea turtles by..., has applied in due form for a permit to take green (Chelonia mydas), hawksbill (Eretmochelys imbricata...), leatherback (Dermochelys coriacea), and unidentified hardshell sea turtles for purposes of scientific...

  15. 75 FR 32811 - Emergency Issuance of Endangered Species Permits

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-09

    ... receive and retain, for greater than 45 days, Kemp's Ridley (Lepidochelys kempii), hawksbill (Eretmochelys... olive ridley (Lepidochelys olivacea) sea turtles for veterinary treatment or euthanasia under certain conditions. TE014234, The Turtle Hospital, Marathon, Florida TE12123A, Gumbo Limbo Nature Center, Boca...

  16. 76 FR 23571 - Marine Mammals and Endangered Species; File Nos. 15415 and 14622

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-27

    ...; (2) characterize the aggregations of loggerhead, Kemp's ridley, and hawksbill sea turtles; and (3... during non-linear transect surveys and hand capture loggerhead, Kemp's ridley, and hawksbill sea turtles... given that NMFS has issued two permits to conduct research on marine mammals or sea turtles....

  17. 78 FR 26323 - Endangered Species; File No. 17183

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-06

    ...), hawksbill (Eretmochelys imbricata), and Kemp's ridley (Lepidochelys kempii) sea turtles for purposes of... on the demographics and movements of green, loggerhead, hawksbill, and Kemp's ridley sea turtles off... 39220) that a request for a scientific research permit to take green, loggerhead, hawksbill, and...

  18. 75 FR 16428 - Endangered Species; File Nos. 15112 and 13307-02

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-01

    ... ridley (Lepidochelys kempii), green (Chelonia mydas), and hawksbill (Eretmochelys imbricata) sea turtles... ridley, 50 green, 10 hawksbill, and 50 leatherback sea turtles caught in commercial fisheries would be.... 13307-02: Dr. Hart is authorized to capture up to 30 green, 20 hawksbill, and 20 loggerhead sea...

  19. Multicultural Approaches in Psychotherapy: A Rejoinder

    ERIC Educational Resources Information Center

    Owen, Jesse; Leach, Mark M.; Wampold, Bruce; Rodolfa, Emil

    2011-01-01

    In this rejoinder, the authors address several issues raised by R. L. Worthington and F. R. Dillon (2011) and C. R. Ridley and M. Shaw-Ridley (2011) regarding (a) the measurement of multicultural competencies (MCCs), (b) sampling considerations in multicultural research, and (c) the conceptual frame of multicultural psychotherapy research. The…

  20. Learning to Integrate

    ERIC Educational Resources Information Center

    Osman, Tom

    2004-01-01

    Allan Ridley has many interesting qualities, not least his determination. Though he is totally blind, he doesn't let that stop him pursuing his interests, whether he is water skiing or learning database design. When asked to tutor blind learner Allan Ridley, the author had to give a lot of thought to making the curriculum accessible. This article…

  1. Learning to Integrate

    ERIC Educational Resources Information Center

    Osman, Tom

    2004-01-01

    Allan Ridley has many interesting qualities, not least his determination. Though he is totally blind, he doesn't let that stop him pursuing his interests, whether he is water skiing or learning database design. When asked to tutor blind learner Allan Ridley, the author had to give a lot of thought to making the curriculum accessible. This article…

  2. Shopping for Old and New Wine: A Response

    ERIC Educational Resources Information Center

    Murdock, Nancy L.; Nilsson, Johanna E.; Duan, Changming

    2012-01-01

    With this rejoinder, we address some of the concerns and questions raised by Ridley and Mollen (2012) and Hill (2012). Specially, we reflect upon Ridley and Mollen's commentary about whether the three theories in this major contribution can be deemed emergent or whether they are simply old thought in new packages. We also address Hill's question…

  3. Time Keeps on Ticking: The Experience of Clinical Judgment

    ERIC Educational Resources Information Center

    Spengler, Paul M.; White, Michael J.; Aegisdottir, Stefania; Maugherman, Alan S.

    2009-01-01

    The reactions by Ridley and Shaw-Ridley (EJ832451) and Lichtenberg (EJ832452) to the authors' meta-analysis on the effects of experience on judgment accuracy add positively to what is hoped will become an ever more focused discourse on this most basic question: How can mental health clinical decision making be improved? In this rejoinder, the…

  4. Young "Science Ambassadors" Raise the Profile of Science

    ERIC Educational Resources Information Center

    Ridley, Katie

    2014-01-01

    Katie Ridley, science coordinator at St. Gregory's Catholic Primary School, Liverpool, UK, states that the inspiration for "science ambassadors" came after embarking on the Primary Science Quality Mark programme at their school. Ridley realized that science was just not recognised as such by the children, they talked about scientific…

  5. Multicultural Approaches in Psychotherapy: A Rejoinder

    ERIC Educational Resources Information Center

    Owen, Jesse; Leach, Mark M.; Wampold, Bruce; Rodolfa, Emil

    2011-01-01

    In this rejoinder, the authors address several issues raised by R. L. Worthington and F. R. Dillon (2011) and C. R. Ridley and M. Shaw-Ridley (2011) regarding (a) the measurement of multicultural competencies (MCCs), (b) sampling considerations in multicultural research, and (c) the conceptual frame of multicultural psychotherapy research. The…

  6. Shopping for Old and New Wine: A Response

    ERIC Educational Resources Information Center

    Murdock, Nancy L.; Nilsson, Johanna E.; Duan, Changming

    2012-01-01

    With this rejoinder, we address some of the concerns and questions raised by Ridley and Mollen (2012) and Hill (2012). Specially, we reflect upon Ridley and Mollen's commentary about whether the three theories in this major contribution can be deemed emergent or whether they are simply old thought in new packages. We also address Hill's question…

  7. Time Keeps on Ticking: The Experience of Clinical Judgment

    ERIC Educational Resources Information Center

    Spengler, Paul M.; White, Michael J.; Aegisdottir, Stefania; Maugherman, Alan S.

    2009-01-01

    The reactions by Ridley and Shaw-Ridley (EJ832451) and Lichtenberg (EJ832452) to the authors' meta-analysis on the effects of experience on judgment accuracy add positively to what is hoped will become an ever more focused discourse on this most basic question: How can mental health clinical decision making be improved? In this rejoinder, the…

  8. Young "Science Ambassadors" Raise the Profile of Science

    ERIC Educational Resources Information Center

    Ridley, Katie

    2014-01-01

    Katie Ridley, science coordinator at St. Gregory's Catholic Primary School, Liverpool, UK, states that the inspiration for "science ambassadors" came after embarking on the Primary Science Quality Mark programme at their school. Ridley realized that science was just not recognised as such by the children, they talked about scientific…

  9. Engineering Applications of Bird Flight

    DTIC Science & Technology

    2009-04-27

    are available in the Zoology Department and Southwell Laboratories of Oxford University. These will be used to test models of the automatic flow...Fellow in the Department of Zoology , Oxford University, with expertise in animal flight dynamics and control. Dr Adrian Thomas (MA, PhD) is a University...Lecturer in the Department of Zoology , Oxford University, with expertise in the aerodynamics of animal flight. Dr Marko Bacic (MEng, D.Phil.) is a

  10. Maintaining Realistic Uncertainty in Model and Forecast

    DTIC Science & Technology

    2000-09-30

    Maintaining Realistic Uncertainty in Model and Forecast Leonard Smith Pembroke College Oxford University St. Aldates Oxford OX1 1DW United Kingdom...5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Pembroke College, Oxford University ,,St...evaluation: l-shadowing, probabilistic prediction and weather forecasting. D.Phil Thesis, Oxford University . Lorenz, E. (1995) Predictability-a Partially

  11. 77 FR 20059 - License Amendment To Increase the Maximum Reactor Power Level, Florida Power & Light Company...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-03

    ..., subtropical marine waters located between the mainland and a grouping of barrier islands that form the... Kemp's ridley sea E turtle \\(c)\\. Snails Orthalicus reses Stock Island tree snail T \\(b)\\. \\(a)\\...

  12. 76 FR 71379 - Florida Power & Light Company, Turkey Point, Units 3 and 4; Draft Environmental Assessment and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-17

    ..., subtropical marine waters located between the mainland and a grouping of barrier islands that form the... kempii......... Kemp's ridley sea E turtle \\c\\. Snails Orthalicus reses Stock Island tree T snail \\b\\....

  13. 75 FR 75489 - Endangered and Threatened Species Permit Applications

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-03

    ... provide education to the public about Kemp's ridley sea turtle (Lepidochelys kempii), hawksbill sea turtle (Eretmochelys imbricate), and leatherback sea turtle (Dermochelys coriacea) that are nesting and/or have...

  14. 76 FR 45781 - Endangered Species; File No. 15552

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-01

    ... to take green (Chelonia mydas), hawksbill (Eretmochelys imbricata), loggerhead (Caretta caretta... coriacea), and ] unidentified hardshell sea turtles for the purposes of scientific research. ADDRESSES: The... a scientific research permit to take green, loggerhead, hawksbill, leatherback, Kemp's ridley,...

  15. 77 FR 54566 - Endangered Species; File No. 16134

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-05

    ... (Chelonia mydas), Kemp's ridley (Lepidochelys kempii), hawksbill (Eretmochelys imbricata), leatherback (Dermochelys coriacea), and loggerhead (Caretta caretta) sea turtles for purposes of scientific research... 222-226). The five-year permit authorizes research on leatherback, loggerhead, green, hawksbill,...

  16. 76 FR 61670 - Receipt of an Application for Incidental Take Permit (16230)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-05

    ... application is for the incidental take of ESA- listed adult and juvenile sea turtles associated with otherwise...: Loggerhead (Caretta caretta), green (Chelonia mydas), leatherback (Dermochelys coriacea), hawksbill (Eretmochelys imbricata), and Kemp's ridley (Lepidochelys kempii) sea turtles. Background NMFS issued Permit...

  17. 77 FR 25538 - Quarterly Publication of Individuals, Who Have Chosen To Expatriate

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-30

    ... SOPHIE CLAIRE CHARRON LESLEY JANE CHEN BENJAMIN WEI JIE CHIEW KRISTIE MICHELLE CHOPDAR ANIL CHRISTOPHER... DORSAY RICHNER PHILIPP RIDLEY MATTHEW WHITE RIETZ MARK PETER RING SEAN ERIC ROHR LUKAS ROSSI PAMELA ROUX...

  18. Environmental Assessment for Beach Shoreline Protection at Patrick Air Force Base, Florida

    DTIC Science & Technology

    2012-02-27

    Daytona Beach and south of PAFB in a small area in Palm Beach County. In addition, the Space Coast Audubon Society (website) has considered piping...P.O. Box 4970 Jacksonville, FL 32232-0019 Mr. James Bennett Minerals Management Service 381 Elden Street Mail Stop 4042 Herndon, VA 20170 UNITED...of olive ridley sea turtles (Lepidochelys olivacea). Pages 59-87 in Plotkin, P.T. (editor). Biology and Conservation of Ridley Sea Turtles. John

  19. Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis

    DTIC Science & Technology

    2012-04-01

    Cheloniidae (loggerhead, green, hawksbill , Kemp’s ridley, olive ridley, flatback sea turtle ) Family Dermochelyidae (leatherback sea turtle ) Criteria...Southwood, Higgins et al. (2007) Chelonia mydas Green turtle 8.7 Wood and Wood (1993) Eretmochelys imbricata Hawksbill turtle 7.4 Okuyama, Shimizu et...Journal of Experimental Biology 208: 4181- 4188. Okuyama, J., T. Shimizu, et al. (2010). "Wild Versus Head-Started Hawksbill Turtles Eretmochelys

  20. First approximation to congenital malformation rates in embryos and hatchlings of sea turtles.

    PubMed

    Bárcenas-Ibarra, Annelisse; de la Cueva, Horacio; Rojas-Lleonart, Isaias; Abreu-Grobois, F Alberto; Lozano-Guzmán, Rogelio Iván; Cuevas, Eduardo; García-Gasca, Alejandra

    2015-03-01

    Congenital malformations in sea turtles have been considered sporadical. Research carried out in the Mexican Pacific revealed high levels of congenital malformations in the olive ridley, but little or no information is available for other species. We present results from analyses of external congenital malformations in olive ridley, green, and hawskbill sea turtles from Mexican rookeries on the Pacific coast and Gulf of Mexico. We examined 150 green and hawksbill nests and 209 olive ridley nests during the 2010 and 2012 nesting seasons, respectively. Olive ridley eggs were transferred to a hatchery and incubated in styrofoam boxes. Nests from the other two species were left in situ. Number of eggs, live and dead hatchlings, and eggs with or without embryonic development were registered. Malformation frequency was evaluated with indices of prevalence and severity. Mortality levels, prevalence and severity were higher in olive ridley than in hawksbill and green sea turtles. Sixty-three types of congenital malformations were observed in embryos, and dead or live hatchlings. Of these, 38 are new reports; 35 for wild sea turtles, three for vertebrates. Thirty-one types were found in hawksbill, 23 in green, and 59 in olive ridley. The head region showed a higher number of malformation types. Malformation levels in the olive ridley were higher than previously reported. Olive ridleys seem more prone to the occurrence of congenital malformations than the other two species. Whether the observed malformation levels are normal or represent a health problem cannot be currently ascertained without long-term assessments. © 2015 Wiley Periodicals, Inc.

  1. Nanocomposite Interphases for Improved Transparent Polymer Composite Materials

    DTIC Science & Technology

    2008-08-01

    Nanocomposite Interphases for Improved Transparent Polymer Composite Materials by Daniel J. O’Brien, Jason Robinette, James R. Heflin , and...Jason Robinette Weapons and Materials Research Directorate, ARL James R. Heflin and Jason Ridley Virginia Polytechnic Institue and State... Heflin ,* and Jason Ridley* 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Army Research Laboratory ATTN: AMSRD-ARL

  2. Antimycobacterial, antimicrobial activity, experimental (FT-IR, FT-Raman, NMR, UV-Vis, DSC) and DFT (transition state, chemical reactivity, NBO, NLO) studies on pyrrole-isonicotinyl hydrazine

    NASA Astrophysics Data System (ADS)

    Rawat, Poonam; Singh, R. N.; Ranjan, Alok; Ahmad, Sartaj; Saxena, Rajat

    2017-05-01

    As part of a study of pyrrole hydrazone, we have investigated quantum chemical calculations, molecular geometry, relative energy, vibrational properties and antimycobacterial/antimicrobial activity of pyrrole-2-carboxaldehyde isonicotinyl hydrazone (PCINH), by applying the density functional theory (DFT) and Hartree Fock (HF). Good reproduction of experimental values is obtained and with small percentage error in majority of the cases in comparison to theoretical result (DFT). The experimental FT-IR and Raman wavenumbers were compared with the respective theoretical values obtained from DFT calculations and found to agree well. In crystal structure studies the hydrated PCINH (syn-syn conformer) shows different conformation than from anhydrous form (syn-anti conformer). The rotational barrier between syn-syn and syn-anti conformers of PCINH is 12.7 kcal/mol in the gas phase. In this work, use of FT-IR, FT-Raman, 1H NMR, 13C NMR and UV-Vis spectroscopies has been made for full characterization of PCINH. A detailed interpretation of the vibrational spectrum was carried out with the aid of normal coordinate analysis using single scaling factor. Our results support the hydrogen bonding pattern proposed by reported crystalline structure. The calculated nature of electronic transitions within molecule found to be π → π*. The electronic descriptors study indicates that PCINH can be used as robust synthon for synthesis of new heterocyclic compounds. The first static hyperpolarizability (β0) of PCINH is calculated as 33.89 × 10- 30 esu, (gas phase); 68.79 × 10- 30 (CHCl3), esu; 76.76 × 10- 30 esu (CH2Cl2), 85.16 × 10- 30 esu (DMSO). The solvent induced effects on the first static hyperpolarizability were studied and found to increase as dielectric constants of the solvents increases. Investigated molecule shows better NLO value than Para nitroaniline (PNA). The compound PCINH shows good antifungal and antibacterial activity against Aspergillus niger and gram-positive bacteria Bacillus subtilis, respectively. The compound also shows good antituberculosis activity against Mycobacterium tuberculosis H37Rv using the microplate alamar blue assay (MABA).

  3. Section 504: Private College Receiving Federal Assistance Must Provide Funds for Interpreter Services for Deaf Student--Barnes v. Converse College, 436 F. Supp. 635 (D.S.C. 1977).

    ERIC Educational Resources Information Center

    Barber, Catherine Miller

    1978-01-01

    Section 504's prohibiting discrimination solely on the basis of handicap against otherwise qualified individuals in programs receiving federal funds was the basis of a deaf student's claim that an institution's failure to provide an interpreter violated Section 504. Implications for private colleges and possible grounds for appeal are discussed.…

  4. Generalized Kähler Geometry from Supersymmetric Sigma Models

    NASA Astrophysics Data System (ADS)

    Bredthauer, Andreas; Lindström, Ulf; Persson, Jonas; Zabzine, Maxim

    2006-09-01

    We give a physical derivation of generalized Kähler geometry. Starting from a supersymmetric nonlinear sigma model, we rederive and explain the results of Gualtieri (Generalized complex geometry, DPhil thesis, Oxford University, 2004) regarding the equivalence between generalized Kähler geometry and the bi-hermitean geometry of Gates et al. (Nucl Phys B248:157, 1984). When cast in the language of supersymmetric sigma models, this relation maps precisely to that between the Lagrangian and the Hamiltonian formalisms. We also discuss topological twist in this context.

  5. Interview with daniel C. Dennett.

    PubMed

    1995-01-01

    Daniel Dennett was educated at Harvard and Oxford, receiving his D.Phil. in 1965. After six years at University of California Irvine, he moved to Tufts, where he is Distinguished Professor of Arts and Sciences and Director of the Center for Cognitive Studies. It is the author of articles on many issues in artificial intelligence, psychology, and cognitive ethology, as well as in philosophy. His books are Content and Consciousness (1969), Brainstorms (1978), The Mind's I (with Douglas Hofstadter, 1981). Elbow Room (1984), The Intentional Stance (1987), and Consciousness Explained (1991). His new book, Darwin's Dangerous Idea, will be published by Simon & Schuster in spring, 1995.

  6. Intestinal helminths in immigrants in Naples (Italy): a comparison between two different diagnostic techniques

    PubMed Central

    Esposito, Silvano; Noviello, Silvana; Leone, Sebastiano; Pascale, Renato; Russo, Enrico; Gualdieri, Luciano

    2013-01-01

    Objective To compare two different methods for detection of intestinal parasitic in immigrants from high risk geographic areas for intestinal parasitic diseases. Methods A total of 307 stool specimens were analysed by Ridley method and FLOTAC, a new technique performing a direct count of all parasitic elements. Results : Compared to Ridley method, FLOTAC technique led to fewer negative results (P<0.05), index of a higher sensibility. Conclusions Performing a more accurate detection of parasites appears a goal to reach in terms of public health.

  7. Measurement of Peroxyacetyl Nitrate (PAN), Peroxypropionyl Nitrate (PPN) and Peroxymethacryloyl Nitrate (MPAN) during TRACE-P

    NASA Technical Reports Server (NTRS)

    Flocke, Frank; Weinheimer, Andrew J.

    2003-01-01

    In Fall 2000, the PANs gas chromatograph (GC) was improved and prepared for installation on the NASA P-3. A number of experiments were conducted in conjunction with the NCAR NO,, instrument (B. Ridley) to settle some of the fine details of the output of the calibration system for each instrument. In addition, the sampling frequency was improved.

  8. 75 FR 33578 - Endangered Species; File Nos. 14508 and 14655

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-14

    ...Notice is hereby given that Inwater Research Group, Inc. [Permit no. 14508, Principal Investigator, Michael Bresette] Jensen Beach, FL and Jane Provancha [Permit No. 14655], Cape Canaveral, FL have been issued permits to take take green (Chelonia mydas), loggerhead (Caretta caretta), hawksbill (Eretmochelys imbricata), and Kemp's ridley (Lepidochelys kempii) sea turtles for purposes of scientific research.

  9. ADHD Assessment and Diagnosis in Canada: An Inconsistent but Fixable Process

    ERIC Educational Resources Information Center

    Edmunds, Alan; Martsch-Litt, Shelley

    2008-01-01

    Canadian teachers in inclusive classrooms are encountering more students with ADHD-like behaviours and making more referrals for formal diagnosis of the condition. Previous research suggests that ADHD diagnoses are susceptible to highly inconsistent and arbitrary assessment processes/criteria (Sanford & Ridley, 1995), thus probably…

  10. Environmental Assessment of Building Demolition at Test Area A-15 (RCS 98-571, 98-572, 98-573, 00-522, 00-523, and 00-731)

    DTIC Science & Technology

    2004-02-01

    Turtles Green sea turtle Chelonia mydas Endangered* Endangered Hawksbill sea turtle Eretmochelys imbricata Endangered Endangered Kemp’s ridley...green turtle ( Chelonia mydas ), typically nest during the months from May through August with hatching occurring from late July through October

  11. 76 FR 33245 - Endangered Species; File No. 15135

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    ... turtles, 5 Kemp's ridleys, 5 loggerheads, 15 greens, 2 hawksbills, and 2 leatherbacks may be mortalities... Isle, NC 28594, has been issued a permit to take threatened and endangered sea turtles for purposes... Register (75 FR 11863) that a request for a scientific research permit to take sea turtles had...

  12. Gulfport Harbor, Mississippi. Final Environmental Impact Statement

    DTIC Science & Technology

    1989-06-01

    turtle (Chelonia mydas), hawksbill (Eretmochelys imbricata), leatnerback (Dermochelys coriacea) and the Atlantic ridley (Lepidochelys kempi). Loggerhead...Sound submersed grass beds are restricted to the northern shores of the barrier islands. These areas are characterized by turtle grass (Thalassia...sea turtles . Many shorebirds and wading birds frequent the islands including herons, egrets, terns, gulls, and black EIS-22 skimmers (Rynchops nigra

  13. 75 FR 9868 - Endangered Species; File No. 14622

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-04

    ... aggregations of loggerhead, Kemp's ridley, and hawksbill sea turtles; and (3) determine the movements... hawksbill sea turtles annually during capture- mark-recapture studies. Captured turtles would be examined..., Jacksonville, FL 32218, has applied in due form for a permit to take green (Chelonia mydas),...

  14. 76 FR 78890 - Endangered Species; File No. 15566

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-20

    ... (Chelonia mydas), 1 leatherback (Dermochelys coriacea), and 1 hawksbill (Eretmochelys imbricata) sea turtle... loggerhead, one Kemp's ridley, one green, one leatherback, and one hawksbill sea turtle could be accidentally... health of sea turtles. Captures occur annually in coastal waters between Winyah Bay, SC and St....

  15. Decline of the Sea Turtles: Causes and Prevention.

    ERIC Educational Resources Information Center

    National Academy of Sciences - National Research Council, Washington, DC. Commission on Life Sciences.

    A report submitted by the Committee on Sea Turtle Conservation, addresses threats to the world's sea turtle populations to fulfill a mandate of the Endangered Species Act Amendments of 1988. It presents information on the populations, biology, ecology, and behavior of five endangered or threatened turtle species: the Kemp's ridley, loggerhead,…

  16. Pascagoula Harbor, Mississippi, Feasibility Report on Improvement of the Federal Deep-Draft Navigation Channel. Volume 1. Main Report and Environmental Impact Statement.

    DTIC Science & Technology

    1985-03-01

    turtle (Caretta caretta caretta), green sea turtle (Chelonia mdas), eastern indigo snake (Drymarchon corais couperi), peregrine falcon (Falco... sea turtle (Chelonia mydas) and the Atlantic ridley (Lepidochelys kempi), may enter Mississippi Sound. The loggerhead turtle (Caretta caretta caretta... sea turtle , eastern indigo snake, peregrine falcon, bald eagle, brown pelican, Bachman’s warbler, Florida panther, Atlantic sturgeon, the southern

  17. Analysis and Recommendation for a Fifteen Percent Cut in Space and Naval Warfare Command for Management Support Services

    DTIC Science & Technology

    2013-06-30

    Tick and Professor Steve Landry for their direction, vision , and patience in the preparation of this thesis. This product would not have been...Judith Downey of Scotia, NY, and has two sons named Ridley Penn (4) and newborn Jasper Drake. They currently reside in Monterey, CA. ^Åèìáëáíáçå

  18. Key members of the XS-1 Research Team

    NASA Technical Reports Server (NTRS)

    1948-01-01

    NACA Muroc Flight Test Unit XS-1 Team members and USAF Pilots. From Left to Right: Joseph Vensel, Head of Operations; Gerald Truszynski, Head of Instrumentation; Captain Charles Chuck Yeager, USAF pilot; Walter Williams, Head of the Unit; Major Jack Ridley, USAF pilot; and De E. Beeler, Head of Engineers.

  19. Key members of the XS-1 research team

    NASA Technical Reports Server (NTRS)

    1948-01-01

    NACA Muroc Flight Test Unit XS-1 Team members and USAF Pilots.From Left to Right: Joseph Vensel, Head of Operations; Gerald Truszynski, Head of Instrumentation; Captain Charles 'Chuck' Yeager, USAF pilot; Walter Williams, Head of the Unit; Major Jack Ridley, USAF pilot; and De E. Beeler, Head of Engineers.(1947)

  20. Learning from Experience: A Report from Mexico's Turtle Trip 2000.

    ERIC Educational Resources Information Center

    Jankowska, Marta Maja

    2000-01-01

    Fifteen high school students and adults from Idaho traveled to Mexico to assist the One World Workforce with monitoring the nests of olive ridley sea turtles. Only 1 percent of these endangered turtles mature to adulthood. The volunteers protected the eggs from poachers and helped the hatchlings get safely to the water. (TD)

  1. Forest biodiversity and woody biomass harvesting

    Treesearch

    Deahn M. Donner; T. Bently Wigley; Darren A. Miller

    2017-01-01

    With the expected increase in demand for woody biomass to help meet renewable energy needs, one principal sustainability question has been whether this material can be removed from forest stands while still conserving biological diversity and retaining ecosystem functioning (Hecht et al. 2009; Berch, Morris, and Malcolm 2011; Ridley et al. 2013). In general,...

  2. A Positive Psychology That Matters

    ERIC Educational Resources Information Center

    Lopez, Shane L.; Magyar-Moe, Jeana L.

    2006-01-01

    The Major Contribution intended to situate positive psychology in counseling psychology's past and future and in the complex world we live and work in today. The four reactions (Frazier, Lee,& Steger; Gerstein; Linley; Mollen, Ethington,& Ridley) provide new insights into how counseling psychology has and will contribute to the study of human…

  3. Introduction to the Special Section on Genomics

    ERIC Educational Resources Information Center

    Grigorenko, Elena L.; Dozier, Mary

    2013-01-01

    The debate about the relevance of human genetics knowledge to everyday life has been marked by fluctuations of interest and enthusiasm. The negative impact of eugenics on the public consciousness suppressed dialogue between geneticists and the public for most of the second half of the 20th century (Ridley, 1999). For the most part, nongeneticists…

  4. 78 FR 14259 - Magnuson-Stevens Act Provisions; Fisheries off West Coast States; Pacific Coast Groundfish...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-05

    ... adversely affect green sea turtles, olive ridley sea turtles, loggerhead sea turtles, sei whales, North Pacific right whales, blue whales, fin whales, sperm whales, Southern Resident killer whales, Guadalupe..., humpback whales, Steller sea lions, and leatherback sea turtles. The opinion also concludes that...

  5. 78 FR 3848 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-17

    ... adversely affect green sea turtles, olive ridley sea turtles, loggerhead sea turtles, sei whales, North Pacific right whales, blue whales, fin whales, sperm whales, Southern Resident killer whales, Guadalupe..., humpback whales, Steller sea lions, and leatherback sea turtles. The opinion also concludes that...

  6. Photo Surfing in Blade Runner

    ERIC Educational Resources Information Center

    Ohler, Jason

    2005-01-01

    This month's "Mining Movies" looks at Blade Runner, Ridley Scott's film set in the year 2019. It is a sad time for Earth, which is in the midst of environmental degradation so severe that other planets are being prepared for colonization. The main source of labor for this preparation work are "replicants," organic robots that look and behave like…

  7. [Book review] Fish and fishes of Saint Helena Island, by Alasdair J. Edwards

    USGS Publications Warehouse

    Smith-Vaniz, W.F.

    1991-01-01

    Review of: FISH AND FISHERIES OF SAINT HELENA ISLAND. By AlasdairJ. Edwards. 1990. Available from the author, Department of Biology, Ridley Building, University of Newcastle upon Tyne, NE1 7RU, England, 152 p., 24 p. color plates, £14.50 (or US$25.) surface, £17.00 (or US$30.)

  8. IPV among Adolescent Reproductive Health Patients: The Role of Relationship Communication

    ERIC Educational Resources Information Center

    Messinger, Adam M.; Davidson, Leslie L.; Rickert, Vaughn I.

    2011-01-01

    Population-specific data on factors that affect intimate partner violence (IPV) are needed on female adolescents and young adults, a cohort at greatest risk of IPV in the United States (Rennison, 2001). Studies have frequently overlooked the role of relationship communication as a gatekeeper to IPV (Ridley & Feldman, 2003). To address this…

  9. Introduction to the Special Section on Genomics

    ERIC Educational Resources Information Center

    Grigorenko, Elena L.; Dozier, Mary

    2013-01-01

    The debate about the relevance of human genetics knowledge to everyday life has been marked by fluctuations of interest and enthusiasm. The negative impact of eugenics on the public consciousness suppressed dialogue between geneticists and the public for most of the second half of the 20th century (Ridley, 1999). For the most part, nongeneticists…

  10. A Decision Optimising Technique for Planners

    ERIC Educational Resources Information Center

    Openshaw, Stan; Whitehead, Paddy

    1975-01-01

    Draws attention to an existing methodology for handling decision-making in a typical planning situation of interrelated alternatives and data deficiency, and describes several important extensions that have recently been made to it. (Oriel Press Limited, 32 Ridley Place, Newcastle upon Tyne, NE1 8LH, Great Britain, $7.00 yearly.) (Author)

  11. Photo Surfing in Blade Runner

    ERIC Educational Resources Information Center

    Ohler, Jason

    2005-01-01

    This month's "Mining Movies" looks at Blade Runner, Ridley Scott's film set in the year 2019. It is a sad time for Earth, which is in the midst of environmental degradation so severe that other planets are being prepared for colonization. The main source of labor for this preparation work are "replicants," organic robots that look and behave like…

  12. Learning from Experience: A Report from Mexico's Turtle Trip 2000.

    ERIC Educational Resources Information Center

    Jankowska, Marta Maja

    2000-01-01

    Fifteen high school students and adults from Idaho traveled to Mexico to assist the One World Workforce with monitoring the nests of olive ridley sea turtles. Only 1 percent of these endangered turtles mature to adulthood. The volunteers protected the eggs from poachers and helped the hatchlings get safely to the water. (TD)

  13. A Positive Psychology That Matters

    ERIC Educational Resources Information Center

    Lopez, Shane L.; Magyar-Moe, Jeana L.

    2006-01-01

    The Major Contribution intended to situate positive psychology in counseling psychology's past and future and in the complex world we live and work in today. The four reactions (Frazier, Lee,& Steger; Gerstein; Linley; Mollen, Ethington,& Ridley) provide new insights into how counseling psychology has and will contribute to the study of human…

  14. IPV among Adolescent Reproductive Health Patients: The Role of Relationship Communication

    ERIC Educational Resources Information Center

    Messinger, Adam M.; Davidson, Leslie L.; Rickert, Vaughn I.

    2011-01-01

    Population-specific data on factors that affect intimate partner violence (IPV) are needed on female adolescents and young adults, a cohort at greatest risk of IPV in the United States (Rennison, 2001). Studies have frequently overlooked the role of relationship communication as a gatekeeper to IPV (Ridley & Feldman, 2003). To address this…

  15. Parenting the Gifted: The Ongoing Riddle of Which Nurture is Best for What Nature: Parents Promoting Gifted Potential

    ERIC Educational Resources Information Center

    Haensly, Patricia

    2004-01-01

    Matt Ridley, an Oxford-trained zoologist and science writer whose latest book is "Nature via Nurture: Genes, Experience, and What Makes Us Human" (2003a), wrote such an impressively clear and fascinating piece on "What Makes You Who You Are" that the author decided to use it to introduce the continuing pursuit of "What do I do to best promote…

  16. Single-chain polybutadiene organometallic nanoparticles: an experimental and theoretical study† †Electronic supplementary information (ESI) available: Detailed experimental procedures and characterization of ONPs including: 1H and 13C NMR, SEC, DLS, DSC, TGA, UV-vis, GC-MS spectra and computational calculations. See DOI: 10.1039/c5sc04535e Click here for additional data file.

    PubMed Central

    Berkovich, Inbal; Mavila, Sudheendran; Iliashevsky, Olga; Kozuch, Sebastian

    2016-01-01

    High molecular weight polybutadienes and rhodium complexes were used to produce single chain organometallic nanoparticles. Irradiation of high cis-polybutadiene in the presence of a photosensitizer isomerised the double bonds to produce differing cis/trans ratios within the polymer. Notably, a higher cis percentage of carbon–carbon double bonds within the polymer structure led to faster binding of metal ions, as well as their faster removal by competing phosphine ligands. The experimental results were supported and rationalized by DFT computations. PMID:28936327

  17. Orthogonal halogen and hydrogen bonds involving a peptide bond model† †Electronic supplementary information (ESI) available: Experimental part, DSC, IR spectroscopic and crystallographic data. CCDC 899779–899785. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4ce01514b Click here for additional data file. Click here for additional data file.

    PubMed Central

    Vasylyeva, Vera; Nayak, Susanta K.; Cavallo, Gabriella; Resnati, Giuseppe

    2014-01-01

    The peptide bond model N-methylacetamide self-assembles with a range of dihalotetrafluorobenzenes forming co-crystals that all show the occurrence of orthogonal hydrogen and halogen bonds. PMID:25663816

  18. Edward Lawrence Powers, Jr. December 30, 1915 - August 1, 2005; In Memorium: "It is only needed to say that he was a man ahead of his time, a man who led radiation research in all that he did." Michael G. Simic, Ph.D., D.Sc.; August, 2005

    NASA Technical Reports Server (NTRS)

    Richmond, Robert C.

    2005-01-01

    Larry Powers was a man of commitment: to roots, family, science, and large appetites. He grew up in Charleston, South Carolina, during the Great Depression that defined his remarkable work ethic and value for contribution. He graduated from the municipal College of Charleston in 1938 with majors in biology, chemistry, and mathematics. That same year, he married his wife Elly of Charleston, with whom he had seven daughters by the early years of his eras of discovery in 1959. He was awarded an Honorary Doctor of Letters from the College of Charleston in 1974, and retired there with Elly in 1987 as a Professor in Residence. Having obtained his Ph.D. from Johns Hopkins University in genetics and protozoology (1941), and having begun his professional career at the University of Notre Dame (Instructor and Assistant Professor, 1941-1945), Larry was often heard to comment on traditions of excellence in education and football, with adamant priority given to the first but without allowance for failure in the second.

  19. Development of Improved Printed Wiring Board Inner Layer Adhesion.

    DTIC Science & Technology

    1982-06-01

    Maleimide End Groups of Kerimid 601 82 40 The 1, 4-Dione Structure of Cured Maleimide Resin 82 41 DSC of Kerimid 601 83 42 DSC of Mica Prepreg 84 4 43 DSC of...Oak-Atlantic Prepreg 85 44 Aging Effects On the Low Temperature DSC Peaks for 87 Mica Prepreg 45 Aging Effects on Low Temperature DSC Peaks for 88...Prepreg 48 Infrared Spectrum of Norplex Polyimide 96 49 DSC Profile of Norplex Polyimide 97 * 50 TMA Profile of Norplex Polyimide 98 51 TGA Profile of

  20. Environmental effects of dredging: Alternative dredging equipment and operational methods to minimize sea turtle mortalities. Technical notes

    SciTech Connect

    Dickerson, D.D.; Nelson, D.A.

    1990-12-01

    Five species of sea turtles occur along the United States coastlines and are listed as threatened or endangered. The loggerhead sea turtle (Caretta caretta) is listed as threatened, while the Kemp`s ridley (Lepidochelys kenipi), the hawksbill (Eretmochelys imbricata), and the leatherback (Dermochelys coriacea) are all less abundant and listed as endangered. Florida breeding populations of the green sea turtle (Chelonia mydas) are listed as endangered, but green turtles in other US waters are considered threatened. The National Marine Fisheries Service (NMFS) has determined, based on the best available information, that because of their life cycle and behavioral patterns only the loggerhead, the green, and the Kemp`s ridley are put at risk by hopper dredging activities (Studt 1987).

  1. [Cloacal and nasal bacterial flora of Lepidochelys olivacea (Testudines: Cheloniidae) from the North Pacific Coast of Costa Rica].

    PubMed

    Santoro, Mario; Orrego, Carlos Mario; Hernández Gómez, Giovanna

    2006-03-01

    Cloacal and nasal bacterial flora of Lepidochelys olivacea (Testudines: Cheloniidae) from the North Pacific coast of Costa Rica. The aerobic cloacal and nasal bacterial flora of 45 apparently healthy female olive ridley sea turtles (Lepidochelys olivacea) was studied at Nancite nesting beach, in Santa Rosa National Park (Costa Rican North Pacific) during July and August 2002. Bacterial samples were obtained by inserting sterile swabs directly into the cloaca and the nasal cavities of the turtles. Ninety-nine aerobic bacterial isolates, including 10 Gram-negative and 5 Gram-positive bacteria, were recovered. The most common bacteria cultured were Aeromonas spp. (13/45) and Citrobacter freundi (6/45) from cloacal samples and Bacillus spp. (32/45), Staphylococcus aureus (6/45) and Corynebacterium spp. (5/45) from nasal ducts. The results of the present study showed that the aerobic bacterial flora of nesting female olive ridleys was composed of several potential human and animal microbe pathogens.

  2. Evaluation of hematology and serum biochemistry of cold-stunned green sea turtles (Chelonia mydas) in North Carolina, U.S.A.

    PubMed

    Anderson, Eric T; Harms, Craig A; Stringer, Elizabeth M; Cluse, Wendy M

    2011-06-01

    Hypothermia or cold-stunning is a condition in which the body temperature of an animal decreases below normal physiologic range and which has been linked to severe morbidity in sea turtles. Reports have focused on the physiologic changes caused by cold-stunning in Kemp's Ridley sea turtles (Lepidochelys kempii) and loggerhead sea turtles (Caretta caretta), but few have evaluated the green sea turtle (Chelonia mydas). This study evaluated hematologic and serum biochemical profiles of cold-stunned green sea turtles in North Carolina, USA. When compared with healthy, free-ranging juvenile green turtles from the same region, cold-stunned turtles exhibited hypoglycemia, hypocalcemia (both total and ionized calcium), hyponatremia, hypokalemia, hypoproteinemia, hypoalbuminemia, hyperphosphatemia, and elevations in uric acid and blood urea nitrogen. These findings contrast with some previously reported changes in cold-stunned Kemp's Ridley and loggerhead sea turtles. These results emphasize the importance of basing therapeutic regimens on biochemical analyses in cold-stunned sea turtles.

  3. Results from the chemical analysis of oily residue samples taken from stranded juvenile sea turtles collected from Padre and Mustang Islands, Texas. Special report (Final)

    SciTech Connect

    Overton, E.B.; Byrne, C.J.; McFall, J.A.; Antoine, S.R.; Laseter, J.L.

    1983-12-01

    Juvenile Kemp's Ridley sea turtles were released June 7, 1983 off the Texas coast by the National Marine Fisheries Service, as part of an U.S. - Mexico cooperative effort to augment the natural breeding stock of the endangered species. Between one and six days later many dead or distressed Kemp's Ridleys were found stranded on Padre and Mustang Islands with oily residues in the mouth and esophagus. Six samples were analyzed for Ni/V content API gravity, stable C, H, and S isotopes, and hydrocarbon composition with high-resolution gas chromatography and HRGC-mass spectrometry. Results were: (1) oils came from multiple sources, (2) composition was predominantly in the n-C20 to n-C32 range (waxy paraffins), (3) residues were most probably from discarded tanker cleaning operations.

  4. Multicultural approaches in psychotherapy: A rejoinder.

    PubMed

    Owen, Jesse; Leach, Mark M; Wampold, Bruce; Rodolfa, Emil

    2010-12-20

    In this rejoinder, the authors address several issues raised by R. L. Worthington and F. R. Dillon (2011) and C. R. Ridley and M. Shaw-Ridley (2011) regarding (a) the measurement of multicultural competencies (MCCs), (b) sampling considerations in multicultural research, and (c) the conceptual frame of multicultural psychotherapy research. The authors challenge the wisdom of exploring MCCs in psychotherapy research and provide a different framework to understand therapists' multicultural effectiveness with clients based on their cultural race/ethnicity. Additionally, the concept of therapists' multicultural orientation or approach is introduced to illuminate the process of aligning with clients about salient cultural issues in psychotherapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved).

  5. The 2010 Oil Spill: Minerals Management Service (MMS) and National Environmental Policy Act (NEPA)

    DTIC Science & Technology

    2010-06-04

    Fin Whale • Sei Whale • Humpback Whale • Sperm Whale • West Indian Manatee • Leatherback turtle • Green turtle • Hawksbill turtle • Kemp’s...and fish habitat; sea turtles ; coastal and seafloor habitats; areas of special concern; socio-economic impacts; archeological resources; tourism and...Ridley turtle • Loggerhead turtle • Gulf Sturgeon • Whooping crane • Piping plover • Alabama beach mouse • Choctawhatchee beach mouse • St. Andrew

  6. The 2010 Oil Spill: MMS/BOEMRE and NEPA

    DTIC Science & Technology

    2010-08-19

    turtle , • Hawksbill turtle , • Kemp’s Ridley turtle , • Loggerhead turtle , • Gulf Sturgeon, • Whooping crane, • Piping plover, • Alabama beach...mammals and birds; fish, fisheries, and fish habitat; sea turtles ; coastal and seafloor habitats; areas of special concern; socioeconomic impacts...Northern Right Whale, • Blue Whale, • Fin Whale, • Sei Whale, • Humpback Whale, • Sperm Whale, • West Indian Manatee, • Leatherback turtle , • Green

  7. Environmental Assessment Military Family Housing Privatization Tyndall Air Force Base, Florida

    DTIC Science & Technology

    2005-07-01

    American alligator T SSC Gopher tortoise SSC Green sea turtle E E Hawksbill sea turtle E E Kemp’s Ridley turtle E E Leatherback...Southeastern American kestrel T Violet-flowered butterwort T E Tricolor heron SSC White ibis SSC REPTILES Alligator snapping turtle SSC...sea turtle E E Loggerhead sea turtle T T MAMMALS Choctawhatchee beach mouse E E Florida black bear T Manatee E E St. Andrew

  8. Environmental Assessment for the Orbital/Sub-Orbital Program

    DTIC Science & Technology

    2006-07-01

    Dermochelys coriacea E E Green sea turtle Chelonia mydas E E Loggerhead sea turtle Caretta caretta T T Hawksbill sea turtle Eretmochelys imbricata...the waters offshore at Cape Canaveral AFS (Table 3-14), all but the Hawksbill and Kemp’s ridley sea turtles are known to nest on station beaches...Green sea turtle Chelonia mydas E, T X X Hawksbill sea turtle Eretmochelys imbricata E X X Loggerhead sea turtle Caretta caretta T X X Olive

  9. Sources of Vibrio mimicus Contamination of Turtle Eggs

    PubMed Central

    Acuña, María T.; Díaz, Gerardo; Bolaños, Hilda; Barquero, Candy; Sánchez, Olga; Sánchez, Luz M.; Mora, Grettel; Chaves, Anny; Campos, Elena

    1999-01-01

    Vibrio mimicus contamination of sand increased significantly during the arrival of the olive ridley sea turtles (Lepidochelys olivacea) at Ostional anidation beach, Costa Rica. Statistical analysis supports that eggs are contaminated with V. mimicus by contact with the sand nest. V. mimicus was isolated from eggs of all nests tested, and ctxA+ strains were found in 31% of the nests, all of which were near the estuary. PMID:9872804

  10. Sample Fabrication and Experimental Approach for Studying Interfacial Sliding in Thin Film-Substrate Systems

    DTIC Science & Technology

    2006-09-01

    Technology 14.5 (1998): 405-410. 19. Zuruzi, A. S., H. Li, and G. Dong. "Diffusion Bonding of Aluminium Alloy 6061 in Air Using an Interface...428. 18. Huang, Y., F. J. Humphreys, N. Ridley, and Z. C. Wang. "Diffusion Bonding of Hot Rolled 7075 Aluminium Alloy." Materials Science and...and Takashi Ohnishi. "Effect of Aluminium Oxide Caps on Hillock Formation in Aluminium Alloy Films." Thin Solid Films 349 (1999): 191-198. 53

  11. Low-Temperature Superplasticity of Ultra-Fine-Grained Ti-6Al-2Sn-4Zr-2Mo-0.1Si Alloy

    DTIC Science & Technology

    2009-03-31

    of surface (alpha case), which deteriorates superplasticity [32], the specimens were coated with delta glaze . All the samples were tested using...maps. The plasticity and creep of metals and ceramics , Pergamon Press (Oxford), 1982. p.44. [49] Guo ZX, Ridley N. Mater Sci Technol 1987;3:945. [50] Park JE, Semiatin SL, Lee CS, Chang YW. Mater Sci Eng A 2005;A410-411:124.

  12. IMPACT - Integrated Modeling of Perturbations in Atmospheres for Conjunction Tracking

    DTIC Science & Technology

    2013-09-01

    Satellite Orbits, Kauai , Hawaii , Feb 2013, 2013. [34] K.J. Demars, M.K. Jah, P.W.J. Schumacher, Initial Orbit Determination using Short-Arc and...Eric Kelecy, Thomas Ridley, Aaron McLaughlin, Craig Intended for: AMOS Conference, 2013-09-10/2013-09-13 (Wailea, Maui, Hawaii , United States...more complexity to map that change to the storage backend (hence our initial preference for HDF, which simplifies this mapping ). Through these

  13. Efficient Multi-Source Data Fusion for Decentralized Sensor Networks

    DTIC Science & Technology

    2006-10-01

    Information Fusion, 7-10 August 2001, Montreal, Canada. [2] E. Nettleton , “Decentralised Architectures for Tracking and Navigation with Multiple Flight...Proceedings of the 5th International Conference on Information Fusion, 8-11 July 2002, Annapolis, MD. [16] M. Ridley, E Nettleton , S. Sukkarieh and H...Decentralized Sensing Networks,” Proceedings of the 4th International Conference on Information Fusion, 7-10 August 2001, Montreal, Canada. [2] E. Nettleton

  14. Intraocular lens providing good vision 23 years after placement.

    PubMed Central

    Gillan, J. G.

    1977-01-01

    A Ridley Perspex lens was placed in the posterior chamber of a man's eye 23 years ago; 20/25 vision has been maintained since. This technique, first carried out in 1949, has been abandoned because of the high incidence of lens dislocation and glaucoma, but many modified versions of the lens have been produced. Implantation of intraocular lenses is still considered experimental, though careful selection of cases and meticulous surgical procedure can yield good results. PMID:608150

  15. Why some Jehovah's Witnesses accept blood and conscientiously reject official Watchtower Society blood policy

    PubMed Central

    Elder, L.

    2000-01-01

    In their responses to Dr Osamu Muramoto (hereafter Muramoto) Watchtower Society (hereafter WTS) spokesmen David Malyon and Donald Ridley (hereafter Malyon and Ridley),1–3 deny many of the criticisms levelled against the WTS by Muramoto.4–6 In this paper I argue as a Jehovah's Witness (hereafter JW) and on behalf of the members of AJWRB that there is no biblical basis for the WTS's partial ban on blood and that this dissenting theological view should be made clear to all JW patients who reject blood on religious grounds. Such patients should be guaranteed confidentiality should they accept whole blood or components that are banned by the WTS. I argue against Malyon's and Ridley's claim that WTS policy allows freedom of conscience to individual JWs and that it is non-coercive and non-punitive in dealing with conscientious dissent and I challenge the notion that there is monolithic support of the WTS blood policy among those who identify themselves as JWs and carry the WTS "advance directive". Key Words: Blood transfusion • Jehovah's Witnesses • Watchtower • autonomy PMID:11055042

  16. Marine turtle mitogenome phylogenetics and evolution.

    PubMed

    Duchene, Sebastián; Frey, Amy; Alfaro-Núñez, Alonzo; Dutton, Peter H; Thomas P Gilbert, M; Morin, Phillip A

    2012-10-01

    The sea turtles are a group of cretaceous origin containing seven recognized living species: leatherback, hawksbill, Kemp's ridley, olive ridley, loggerhead, green, and flatback. The leatherback is the single member of the Dermochelidae family, whereas all other sea turtles belong in Cheloniidae. Analyses of partial mitochondrial sequences and some nuclear markers have revealed phylogenetic inconsistencies within Cheloniidae, especially regarding the placement of the flatback. Population genetic studies based on D-Loop sequences have shown considerable structuring in species with broad geographic distributions, shedding light on complex migration patterns and possible geographic or climatic events as driving forces of sea-turtle distribution. We have sequenced complete mitogenomes for all sea-turtle species, including samples from their geographic range extremes, and performed phylogenetic analyses to assess sea-turtle evolution with a large molecular dataset. We found variation in the length of the ATP8 gene and a highly variable site in ND4 near a proton translocation channel in the resulting protein. Complete mitogenomes show strong support and resolution for phylogenetic relationships among all sea turtles, and reveal phylogeographic patterns within globally-distributed species. Although there was clear concordance between phylogenies and geographic origin of samples in most taxa, we found evidence of more recent dispersal events in the loggerhead and olive ridley turtles, suggesting more recent migrations (<1 Myr) in these species. Overall, our results demonstrate the complexity of sea-turtle diversity, and indicate the need for further research in phylogeography and molecular evolution.

  17. Deepwater Horizon oil spill impacts on sea turtles could span the Atlantic.

    PubMed

    Putman, Nathan F; Abreu-Grobois, F Alberto; Iturbe-Darkistade, Iñaky; Putman, Emily M; Richards, Paul M; Verley, Philippe

    2015-12-01

    We investigated the extent that the 2010 Deepwater Horizon oil spill potentially affected oceanic-stage sea turtles from populations across the Atlantic. Within an ocean-circulation model, particles were backtracked from the Gulf of Mexico spill site to determine the probability of young turtles arriving in this area from major nesting beaches. The abundance of turtles in the vicinity of the oil spill was derived by forward-tracking particles from focal beaches and integrating population size, oceanic-stage duration and stage-specific survival rates. Simulations indicated that 321 401 (66 199-397 864) green (Chelonia mydas), loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempii) turtles were likely within the spill site. These predictions compared favourably with estimates from in-water observations recently made available to the public (though our initial predictions for Kemp's ridley were substantially lower than in-water estimates, better agreement was obtained with modifications to mimic behaviour of young Kemp's ridley turtles in the northern Gulf). Simulations predicted 75.2% (71.9-76.3%) of turtles came from Mexico, 14.8% (11-18%) from Costa Rica, 5.9% (4.8-7.9%) from countries in northern South America, 3.4% (2.4-3.5%) from the United States and 1.6% (0.6-2.0%) from West African countries. Thus, the spill's impacts may extend far beyond the current focus on the northern Gulf of Mexico.

  18. Three closely related herpesviruses are associated with fibropapillomatosis in marine turtles

    USGS Publications Warehouse

    Quackenbush, S.L.; Work, T.M.; Balazs, G.H.; Casey, R.N.; Rovnak, J.; Chaves, A.; duToit, L.; Baines, J.D.; Parrish, C.R.; Bowser, P.R.; Casey, J.W.

    1998-01-01

    Green turtle fibropapillomatosis is a neoplastic disease of increasingly significant threat to the survivability of this species. Degenerate PCR primers that target highly conserved regions of genes encoding herpesvirus DNA polymerases were used to amplify a DNA sequence from fibropapillomas and fibromas from Hawaiian and Florida green turtles. All of the tumors tested (n= 23) were found to harbor viral DNA, whereas no viral DNA was detected in skin biopsies from tumor-negative turtles. The tissue distribution of the green turtle herpesvirus appears to be generally limited to tumors where viral DNA was found to accumulate at approximately two to five copies per cell and is occasionally detected, only by PCR, in some tissues normally associated with tumor development. In addition, herpesviral DNA was detected in fibropapillomas from two loggerhead and four olive ridley turtles. Nucleotide sequencing of a 483-bp fragment of the turtle herpesvirus DNA polymerase gene determined that the Florida green turtle and loggerhead turtle sequences are identical and differ from the Hawaiian green turtle sequence by five nucleotide changes, which results in two amino acid substitutions. The olive ridley sequence differs from the Florida and Hawaiian green turtle sequences by 15 and 16 nucleotide changes, respectively, resulting in four amino acid substitutions, three of which are unique to the olive ridley sequence. Our data suggest that these closely related turtle herpesviruses are intimately involved in the genesis of fibropapillomatosis.

  19. Three closely related herpesviruses are associated with fibropapillomatosis in marine turtles

    USGS Publications Warehouse

    Quackenbush, S.L.; Work, Thierry M.; Balazs, George H.; Casey, Rufina N.; Rovnak, J.; Chaves, A.; duToit, L.; Baines, J.D.; Parrish, C.R.; Bowser, Paul R.; Casey, James W.

    1998-01-01

    Green turtle fibropapillomatosis is a neoplastic disease of increasingly significant threat to the survivability of this species. Degenerate PCR primers that target highly conserved regions of genes encoding herpesvirus DNA polymerases were used to amplify a DNA sequence from fibropapillomas and fibromas from Hawaiian and Florida green turtles. All of the tumors tested (n= 23) were found to harbor viral DNA, whereas no viral DNA was detected in skin biopsies from tumor-negative turtles. The tissue distribution of the green turtle herpesvirus appears to be generally limited to tumors where viral DNA was found to accumulate at approximately two to five copies per cell and is occasionally detected, only by PCR, in some tissues normally associated with tumor development. In addition, herpesviral DNA was detected in fibropapillomas from two loggerhead and four olive ridley turtles. Nucleotide sequencing of a 483-bp fragment of the turtle herpesvirus DNA polymerase gene determined that the Florida green turtle and loggerhead turtle sequences are identical and differ from the Hawaiian green turtle sequence by five nucleotide changes, which results in two amino acid substitutions. The olive ridley sequence differs from the Florida and Hawaiian green turtle sequences by 15 and 16 nucleotide changes, respectively, resulting in four amino acid substitutions, three of which are unique to the olive ridley sequence. Our data suggest that these closely related turtle herpesviruses are intimately involved in the genesis of fibropapillomatosis.

  20. 47 CFR 80.1069 - Maritime sea areas.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... continuous DSC alerting is available as defined by the International Maritime Organization. (2) Sea area A2... in which continuous DSC alerting is available as defined by the International Maritime...

  1. 47 CFR 80.93 - Hours of service.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... If a ship has duplicate GMDSS installations for DSC or INMARSAT, only one of each must be turned on... duplicate GMDSS installations for DSC or INMARSAT, only one of each must be turned on and keeping watch....

  2. 47 CFR 80.1071 - Exemptions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... MARITIME SERVICES Global Maritime Distress and Safety System (GMDSS) General Provisions § 80.1071...-DSC and MF-DSC equipment until one year after the USCG establishes GMDSS coast facilities for Sea...

  3. 47 CFR 80.1071 - Exemptions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... MARITIME SERVICES Global Maritime Distress and Safety System (GMDSS) General Provisions § 80.1071...-DSC and MF-DSC equipment until one year after the USCG establishes GMDSS coast facilities for Sea...

  4. 47 CFR 80.1071 - Exemptions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... MARITIME SERVICES Global Maritime Distress and Safety System (GMDSS) General Provisions § 80.1071...-DSC and MF-DSC equipment until one year after the USCG establishes GMDSS coast facilities for Sea...

  5. Flat-on ambipolar triphenylamine/C60 nano-stacks formed from the self-organization of a pyramid-sphere-shaped amphiphile† †Electronic supplementary information (ESI) available: 1H and 13C NMR spectra, TGA, DSC, XRD, simulated ED patterns, UV-Vis spectra, reduction and oxidation cyclic voltammetry curves. See DOI: 10.1039/c5sc04242a Click here for additional data file.

    PubMed Central

    Liang, Wei-Wei; Huang, Chi-Feng; Wu, Kuan-Yi; Wu, San-Lien; Chang, Shu-Ting; Cheng, Yen-Ju

    2016-01-01

    A giant amphiphile, which is constructed with an amorphous nano-pyramid (triphenylamine, TPA) and a crystalline nano-sphere (C60), was synthesized. Structural characterization indicates that this pyramid-sphere-shaped amphiphile (TPA–C60) forms a solvent-induced ordered phase, in which the two constituent units self-assemble into alternating stacks of two-dimensional (2D) TPA and C60 nano-sheets. Due to the complexity of the molecular structure and the amorphous nature of the nano-pyramid, phase formation was driven by intermolecular C60–C60 interactions and the ordered phase could not be reformed from the TPA–C60 melt. Oriented crystal arrays of TPA–C60, which contain flat-on TPA/C60 nano-stacks, can be obtained via a PDMS-assisted crystallization (PAC) technique. The flat-on dual-channel supramolecular structure of TPA–C60 delivered ambipolar and balanced charge-transport characteristics with an average μ e of 2.11 × 10–4 cm2 V–1 s–1 and μ h of 3.37 × 10–4 cm2 V–1 s–1. The anisotropic charge-transport ability of the pyramid-sphere-shaped amphiphile was further understood based on the lattice structure and the lattice orientation of TPA–C60 revealed from electron diffraction analyses. PMID:28660054

  6. Vapor Pressure Data and Analysis for Selected Organophosphorus Compounds: DIBMP, DCMP, IMMP, IMPA, EMPA, and MPFA

    DTIC Science & Technology

    2017-04-01

    and vapor saturation. The data presented herein have been used to determine temperature–pressure correlations , and the fit constants have been used to...and DSC data only, and the Clausius–Clapeyron equation based on DSC data only ..........6 3. DCMP vapor pressure data and Antoine correlations ... correlations based on all data and DSC data only, and the Clausius–Clapeyron correlation based on DSC data only ...........12 5. Superposition of

  7. Chemistry of Processible Acetylene-Terminated Imides

    DTIC Science & Technology

    1983-08-01

    and consultations in DSC -TGA analyses, FT-IR spectroscopy, NMR spectrometry, and HPLC-GPC analyses were provided by Mr. Philip G. Magallanes, Mr. Herman...11 Differential Scanning Calorimetry ( DSC ) for HR600P (Lot M1126-1) ........ 15 12 Differential Scanning Calorimetry ( DSC ) Curves for Thermid 600 and H...17 14 Gel Permeation Chromatogram for HR605P (Lot M1126-33A) .............. 18 15 Differential Scanning Calorimetry ( DSC ) for HR602P Oligomer (M1126-42

  8. Differential scanning calorimetry of protein-lipid interactions.

    PubMed

    Cañadas, Olga; Casals, Cristina

    2013-01-01

    Differential scanning calorimetry (DSC) is a highly sensitive non-perturbing technique for measuring the thermodynamic properties of thermally induced transitions. This technique is particularly useful for the characterization of lipid/protein interactions. This chapter presents an introduction to DSC instrumentation, basic theory, and methods and describes DSC applications for characterizing protein effects on model lipid membranes. Examples of the use of DSC for the evaluation of protein effects on modulation of membrane domains and membrane stability are given.

  9. Maturing Defense Support of Civil Authorities and the Dual Status Commander Arrangement Through the Lens of Process Improvement

    DTIC Science & Technology

    2015-04-01

    Designate a DCOIC C3 : Establish communications link between regional DCOs, DSC JTF, and DCOIC Information Operations Technology ( IOT ) Mission...resources to fulfill RFAs I3: SECDEF deploys units of the Armed Forces to DSC-led Federal JTF C3 : DSC-led Federal JTF integrates Title 10 forces

  10. 77 FR 33475 - National Institute On Aging; Notice of Closed Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-06

    ... Conference Call). Contact Person: Alicja L. Markowska, Ph.D., DSC, Scientific Review Branch, National... 20892 (Telephone Conference Call). Contact Person: Alicja L. Markowska, Ph.D., DSC, Scientific Review..., Ph.D., DSC, Scientific Review Branch, National Institute On Aging, ] 7201 Wisconsin Avenue,...

  11. 47 CFR 80.310 - Watch required by voluntary vessels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Watches § 80.310 Watch required by voluntary vessels. Voluntary vessels not equipped with DSC must.... Voluntary vessels equipped with VHF-DSC equipment must maintain a watch on 2182 kHz and on either 156.525... used to communicate. Voluntary vessels equipped with MF-HF DSC equipment must have the radio turned...

  12. Properties of UV-Cured Polyurethane Acrylates: Effect of Polyol Type and Molecular Weight

    DTIC Science & Technology

    1984-06-20

    glass transition temperature versus polypropylene oxide molecular weight for the IEM-PP series materials. Figure 5. DSC thermograms of the IEM-ES-25N...before and after one minute of UV-curing. Figure 3. DSC thermograms of the IEM-PP-O series materials before C---) and after (-) UV-curing. Figure 4. DSC

  13. Oral Histories in Meteoritics and Planetary Science--XVI: Grenville Turner

    NASA Astrophysics Data System (ADS)

    Sears, Derek W. G.

    2012-03-01

    In this interview, Grenville Turner (Fig. 1) recounts how he became interested in meteorites during postdoctoral research with John Reynolds at the University of California, Berkeley, after completing a DPhil with Ken Mayne at the University of Oxford. At Berkeley, he worked on xenon isotopes with fellow students Bob Pepin and Craig Merrihue, but Reynolds' insistence that they analyze all the inert gases in their samples meant that they also made important contributions to Ne isotope studies and potassium-argon dating leading to the Ar-Ar technique. In 1964, Grenville obtained a teaching position at the University of Sheffield where he developed his own laboratory for inert gas isotope measurements. After the return of samples from the Moon by the Apollo program, he became involved in determining the chronology of volcanism and major impacts on the Moon. In 1988, Grenville and his team moved to the University of Manchester as part of a national reorganization of earth science departments. During the post Apollo years, Grenville's interest turned to the development of new instrumentation (resonance ionization mass spectrometry and the ion microprobe), and to problems in terrestrial isotope geochemistry, particularly the source of inert gases in fluid inclusions. He received the Leonard Medal of the Meteoritical Society in 1999, and he has also received awards from the Royal Society, the European Association of Geochemistry, and the Royal Astronomical Society.

  14. Clinical application of plasma thermograms. Utility, practical approaches and considerations

    PubMed Central

    Garbett, Nichola C.; Mekmaysy, Chongkham S.; DeLeeuw, Lynn; Chaires, Jonathan B.

    2014-01-01

    Differential scanning calorimetry (DSC) studies of blood plasma are part of an emerging area of the clinical application of DSC to biofluid analysis. DSC analysis of plasma from healthy individuals and patients with various diseases has revealed changes in the thermal profiles of the major plasma proteins associated with the clinical status of the patient. The sensitivity of DSC to the concentration of proteins, their interactions with other proteins or ligands, or their covalent modifications underlies the potential utility of DSC analysis. A growing body of literature has demonstrated the versatility and performance of clinical DSC analysis across a range of biofluids and in a number of disease settings. The principles, practice and challenges of DSC analysis of plasma are described in this article. PMID:25448297

  15. Clinical application of plasma thermograms. Utility, practical approaches and considerations.

    PubMed

    Garbett, Nichola C; Mekmaysy, Chongkham S; DeLeeuw, Lynn; Chaires, Jonathan B

    2015-04-01

    Differential scanning calorimetry (DSC) studies of blood plasma are part of an emerging area of the clinical application of DSC to biofluid analysis. DSC analysis of plasma from healthy individuals and patients with various diseases has revealed changes in the thermal profiles of the major plasma proteins associated with the clinical status of the patient. The sensitivity of DSC to the concentration of proteins, their interactions with other proteins or ligands, or their covalent modification underlies the potential utility of DSC analysis. A growing body of literature has demonstrated the versatility and performance of clinical DSC analysis across a range of biofluids and in a number of disease settings. The principles, practice and challenges of DSC analysis of plasma are described in this article.

  16. Structural basis of adhesive binding by desmocollins and desmogleins

    PubMed Central

    Harrison, Oliver J.; Brasch, Julia; Lasso, Gorka; Katsamba, Phinikoula S.; Ahlsen, Goran; Honig, Barry; Shapiro, Lawrence

    2016-01-01

    Desmosomes are intercellular adhesive junctions that impart strength to vertebrate tissues. Their dense, ordered intercellular attachments are formed by desmogleins (Dsgs) and desmocollins (Dscs), but the nature of trans-cellular interactions between these specialized cadherins is unclear. Here, using solution biophysics and coated-bead aggregation experiments, we demonstrate family-wise heterophilic specificity: All Dsgs form adhesive dimers with all Dscs, with affinities characteristic of each Dsg:Dsc pair. Crystal structures of ectodomains from Dsg2 and Dsg3 and from Dsc1 and Dsc2 show binding through a strand-swap mechanism similar to that of homophilic classical cadherins. However, conserved charged amino acids inhibit Dsg:Dsg and Dsc:Dsc interactions by same-charge repulsion and promote heterophilic Dsg:Dsc interactions through opposite-charge attraction. These findings show that Dsg:Dsc heterodimers represent the fundamental adhesive unit of desmosomes and provide a structural framework for understanding desmosome assembly. PMID:27298358

  17. IgG Autoantibodies Against Desmocollin 3 in Pemphigus Sera Induce Loss of Keratinocyte Adhesion

    PubMed Central

    Rafei, David; Müller, Ralf; Ishii, Norito; Llamazares, Maria; Hashimoto, Takashi; Hertl, Michael; Eming, Rüdiger

    2011-01-01

    Pemphigus is considered an autoimmune bullous skin disorder associated with IgG against the desmosomal components, desmoglein 3 (Dsg3) and desmoglein 1 (Dsg1). This concept is supported by the in vitro and in vivo pathogenicity of anti-Dsg3/Dsg1 IgG and the mucosal blistering phenotype of mice with a genetic deficiency of Dsg3. Mice deficient for another desmosomal adhesion molecule, desmocollin 3 (Dsc3), show a similar pemphigus phenotype, and we investigated the pathogenicity of Dsc3-reactive IgG autoantibodies that were identified previously in a subset of patients with atypical pemphigus. We here demonstrate that IgG against Dsc3 causes loss of adhesion of epidermal keratinocytes. Specifically, IgG against Dsc3 was purified from Dsc3-reactive pemphigus sera by affinity column chromatography using recombinant human Dsc3. Affinity purified IgG was functionally active and did not only react with recombinant Dsc3 but also with epidermis and cultured human keratinocytes. Moreover, Dsc3-reactive IgG induced loss of adhesion of epidermal keratinocytes in a dispase-based keratinocyte dissociation assay that was reversed on pre-adsorption with human Dsc3 but not Dsg3. These findings demonstrate that IgG autoantibodies against an additional component of the desmosomes, Dsc3, induce loss of keratinocyte adhesion and thus may contribute to blister formation in pemphigus. PMID:21281804

  18. 3-Deoxysappanchalcone Promotes Proliferation of Human Hair Follicle Dermal Papilla Cells and Hair Growth in C57BL/6 Mice by Modulating WNT/β-Catenin and STAT Signaling

    PubMed Central

    Kim, Young Eun; Choi, Hyung Chul; Lee, In-Chul; Yuk, Dong Yeon; Lee, Hyosung; Choi, Bu Young

    2016-01-01

    3-Deoxysappanchalcone (3-DSC) has been reported to possess anti-allergic, antiviral, anti-inflammatory and antioxidant activities. In the present study, we investigated the effects of 3-DSC on the proliferation of human hair follicle dermal papilla cells (HDPCs) and mouse hair growth in vivo. A real-time cell analyzer system, luciferase assay, Western blot and real-time polymerase chain reaction (PCR) were employed to measure the biochemical changes occurring in HDPCs in response to 3-DSC treatment. The effect of 3-DSC on hair growth in C57BL/6 mice was also examined. 3-DSC promoted the proliferation of HDPCs, similar to Tofacitinib, an inhibitor of janus-activated kinase (JAK). 3-DSC promoted phosphorylation of β-catenin and transcriptional activation of the T-cell factor. In addition, 3-DSC potentiated interleukin-6 (IL-6)-induced phosphorylation and subsequent transactivation of signal transducer and activator of transcription-3 (STAT3), thereby increasing the expression of cyclin-dependent kinase-4 (Cdk4), fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF). On the contrary, 3-DSC attenuated STAT6 mRNA expression and IL4-induced STAT6 phosphorylation in HDPCs. Finally, we observed that topical application of 3-DSC promoted the anagen phase of hair growth in C57BL/6 mice. 3-DSC stimulates hair growth possibly by inducing proliferation of follicular dermal papilla cells via modulation of WNT/β-catenin and STAT signaling. PMID:27795451

  19. Deepwater Horizon oil spill impacts on sea turtles could span the Atlantic

    PubMed Central

    Putman, Nathan F.; Abreu-Grobois, F. Alberto; Iturbe-Darkistade, Iñaky; Putman, Emily M.; Richards, Paul M.; Verley, Philippe

    2015-01-01

    We investigated the extent that the 2010 Deepwater Horizon oil spill potentially affected oceanic-stage sea turtles from populations across the Atlantic. Within an ocean-circulation model, particles were backtracked from the Gulf of Mexico spill site to determine the probability of young turtles arriving in this area from major nesting beaches. The abundance of turtles in the vicinity of the oil spill was derived by forward-tracking particles from focal beaches and integrating population size, oceanic-stage duration and stage-specific survival rates. Simulations indicated that 321 401 (66 199–397 864) green (Chelonia mydas), loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempii) turtles were likely within the spill site. These predictions compared favourably with estimates from in-water observations recently made available to the public (though our initial predictions for Kemp's ridley were substantially lower than in-water estimates, better agreement was obtained with modifications to mimic behaviour of young Kemp's ridley turtles in the northern Gulf). Simulations predicted 75.2% (71.9–76.3%) of turtles came from Mexico, 14.8% (11–18%) from Costa Rica, 5.9% (4.8–7.9%) from countries in northern South America, 3.4% (2.4–3.5%) from the United States and 1.6% (0.6–2.0%) from West African countries. Thus, the spill's impacts may extend far beyond the current focus on the northern Gulf of Mexico. PMID:26701754

  20. Persistent organic pollutants in fat of three species of Pacific pelagic longline caught sea turtles: Accumulation in relation to ingested plastic marine debris

    USGS Publications Warehouse

    Clukey, Katharine; Lepczyk, Christopher A.; Balazs, George H.; Work, Thierry M.; Li, Qing X.; Bachman, Melanie J.; Lynch, Jennifer M.

    2017-01-01

    In addition to eating contaminated prey, sea turtles may be exposed to persistent organic pollutants (POPs) from ingesting plastic debris that has absorbed these chemicals. Given the limited knowledge about POPs in pelagic sea turtles and how plastic ingestion influences POP exposure, our objectives were to: 1) provide baseline contaminant levels of three species of pelagic Pacific sea turtles; and 2) assess trends of contaminant levels in relation to species, sex, length, body condition and capture location. In addition, we hypothesized that if ingesting plastic is a significant source of POP exposure, then the amount of ingested plastic may be correlated to POP concentrations accumulated in fat. To address our objectives we compared POP concentrations in fat samples to previously described amounts of ingested plastic from the same turtles. Fat samples from 25 Pacific pelagic sea turtles [2 loggerhead (Caretta caretta), 6 green (Chelonia mydas) and 17 olive ridley (Lepidochelys olivacea) turtles] were analyzed for 81 polychlorinated biphenyls (PCBs), 20 organochlorine pesticides, and 35 brominated flame-retardants. The olive ridley and loggerhead turtles had higher ΣDDTs (dichlorodiphenyltrichloroethane and metabolites) than ΣPCBs, at a ratio similar to biota measured in the South China Sea and southern California. Green turtles had a ratio close to 1:1. These pelagic turtles had lower POP levels than previously reported in nearshore turtles. POP concentrations were unrelated to the amounts of ingested plastic in olive ridleys, suggesting that their exposure to POPs is mainly through prey. In green turtles, concentrations of ΣPCBs were positively correlated with the number of plastic pieces ingested, but these findings were confounded by covariance with body condition index (BCI). Green turtles with a higher BCI had eaten more plastic and also had higher POPs. Taken together, our findings suggest that sea turtles accumulate most POPs through their prey rather