955 resultados para Freeze dryer


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Freshwater chlorophycean algae are characteristic organic-walled microfossils in recent coastal and shelf sediments from the Beaufort, Laptev and Kara seas (Arctic Ocean). The persistent occurrence of the chlorophycean algae Pediastrum spp. and Botryococcus cf. braunii in marine palynomorph assemblages is related to the discharge of freshwater and suspended matter from the large Siberian and North American rivers into the Arctic shelf seas. The distribution patterns of these algae in the marine environments reflect the predominant deposition of riverine sediments and organic matter along the salinity gradient from the outer estuaries and prodeltas to the shelf break. Sedimentary processes overprint the primary distribution of these algae. Resuspension of sediments by waves and bottom currents may transport sediments in the bottom nepheloid layer along the submarine channels to the shelf break. Bottom sediments and microfossils may be incorporated into sea ice during freeze-up in autumn and winter leading to an export from the shelves into the deep sea. The presence of these freshwater algae in sea-ice and bottom sediments in the central Arctic Ocean confirm that transport in sea ice is an important process which leads to a redistribution of shallow water microfossils.

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A 270 cm long sediment sequence was recovered with a piston corer from east lobe Bonney, Taylor Valley, Antarctica, and characterized according to its sedimentological, mineralogical, and geochemical properties. It is the first record of such length recovered from east lobe Bonney. The sediment core is mainly composed of halite crystals of different sizes, water, and a relatively low and stable proportion of clastic particles. Although the sediment surface was probably disturbed by the coring process and absence or low contents of organic material or carbonates hampers the establishment of a robust chronology by radiocarbon dating, the core probably contains at least several hundred years of information about the history of the lake and the Bonney basin. Variations in halite crystal sizes and amount as well as variations in the composition of clastic material can be related to past lake level changes and evaporation cycles.

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In this study we reconstruct quantitatively the Middle to Upper Miocene climate evolution in the southern Forecarpathian Basin (Central Paratethys area, Northwest Bulgaria) by applying the coexistence approach to 101 well-dated palynofloras isolated from three cores. The climatic evolution is compared with changes in vegetation and palaeogeography. The Middle Miocene was a period of a subtropical/warm-temperate humid climate with mean annual temperature (MAT) between 16 and 18°C and mean annual precipitation (MAP) between 1100 and 1300 mm. Thereby, during the entire Middle Miocene a trend of slightly decreasing temperatures is observed and only small climate fluctuations occur which are presumably related to palaeogeographic reorganisations. The vegetation shows a corresponding trend with a decrease in abundance of palaeotropic and thermophilous elements. The Upper Miocene is characterised by more diverse climatic conditions, probably depending on palaeogeographic and global climatic transformations. The beginning of this period is marked by a slight cooling and a significant drying of the climate, with MAT 13.3-17°C and MAP 652-759 mm. After that, fluctuations of all palaeoclimate parameters occur displaying cycles of humid/dryer and warmer/cooler conditions, which are again well reflected in the vegetation. Our study provides a first quantitative model of the Middle-Upper Miocene palaeoclimate evolution in Southeastern Europe and is characterised by a relatively high precision and resolution with respect to the climate data and stratigraphy.

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Front Row: Cheryl Pearcy, Kari Kunnen, Kathryn Gleason, Karla Kunnen, Patti Benedict, assistant coach Cathy Wylie,

Middle Row: manager Tim Dryer, Tracy Carr, Erin Martino, Kathleen Berrigan, Lesa Arvia, Mary Campana

Back Row: Amy Carlton (Sports Information), student trainer Amy Brim, athletic trainer Kate Hallada, Renee Swinicki, Kelly Forbis, Kelly Kovach, Michelle Silver, Kim Clark, assistant coach Carol Bruggeman, head coach Carol Hutchins

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Parts I-II issued in 1 vol.

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Mode of access: Internet.

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William S. Gray, John L. Dryer, Rodney H. Brandon, committee to edit the proceedings of the convention.

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Front Row: Cheyl Pearcy, Kari Kunnen, Kathryn Gleason, Karla Kunnen, Patti Benedict, assistant coach Cathy Wylie

Middle Row: manager Tim Dryer, Tracy Carr, Erin Martino, Kathleen Berrigan, Lesa Arvia, Mary Campana

Back Row: Amy Carlton (Sports Information), student trainer Amy Brim, athletic trainer Kate Hallada, Renee Swinicki, Kelly Forbis, Kelly Kovach, Michelle Silver, Kim Clark, assistant coach Carol Bruggeman, head coach Carol Hutchins

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Top Row: Suzanne P. Zeros, Leslie A. Hazle, Deborah L. Thar, Jo-Ann Uhrhammer, Susan M. Revesz, Karla M. Jackson, Laura L. Campbell, Carol T. Dekeyser, Jeanette R. Lewey, Constance B. Squibb, Kristen Eckoff, Martha J. Armantrout, Kathleen A. Duhart, Sara J. Hemming, Carrie L. Malroit, Anne Marie L. Piehl, Rita A. Dobry, Susan A. Wintermeyer

Row 2: Deborah L. Kurzeja, Elanie C. Jenkins, Mary Nehra, June Ellis, Lisa Mediodia, Mary G. Rutz, Diane L. Larson, Mark A. Kempton, Margaret M. Ulchaker, Maureen B. Schreibea, Jan E. Merrick, Holly Russell, Betsy J. hodgman, Maeve N. Boran, Theresa J. Coker, Lisa Moss, Nancy J. Deckert, Nancy R. Bailey

Row 3: Denise M. Zapinski, Michelle M. Post, Elicia baker-Rogers, Lisa A. Mast, Patricia Thomas, Karen A. Bartoluzzi, Jennifer M. Dzieciuch, Margie Von Berge, Nancy Lutz, Pamela Mrstik

Row 4: Elizabeth Doheny, Jacqueline T. Bartone, Lisa A. Pfahler, Sheryl L. Lovelace, Elizabeth A. Bazur, Janet L. Bauman, Delynn M. Dindoffer, Rebecca Waldo

Row 5: Janarl L. Harris, Jeanne M. Cancilla, Amy Garon, Alisa D. Karp, Liz Buchanan, Linda M. Ford.

Row 6: Ondreya Dillard, Linda C. Parks, Tricia Berner, Loranie A. McKaig, Susan M. Bleasdale, Heather L. Colquhoun, Valerie M. Spotts, Marcia L. Fouts

Row 7: Theresa Glick, Carrie L Giltrow, Lisa E. Chapelle, Mary H. Kiledo, Jody Kazmierczak, Patricia E. Goerke, Lisa Weingart, Laura A. Rhead, Pauletta McKivens, Nancy K. Dryer

Row 8: Mary S. Mac Taggart, Lynn M. Stephens, Ann E. Dowling, Amy L. Huntzinger, Patricia A. Schremser, Kathy Hughes, Sally Sample, Cheryl E. Easley, Rhetaugh Dumas, Janice Lindberg, Susan Boehm, Heather Hossack, Susan E. Parry, Amy D. Landau, Michele Mansour, Nancy R. Clark, Sarah Cunningham

Row 9: Rhonda B. Dean, Sandra s. Klein, Cheryl L. Goddard, Toni Rene Dawson, Sara R. Farhat, Lisa M. Kane, Kaye M. Lewandowski, Jennifer A. Blashill, Susan L. Bradley, Mary McGuiness, Ann Dameron, Karolyn L. Maron, Debra Fisher, Rebecca Vredenburg, Elaine B. Fritz, Mary A. Alphenaar, Kathy Rentenbach, Barbara J. Wolff

Row 10: Nancy L. Minegar, Mary E. Conners, Susan E. Kuzma, M. Maureen O'Conner, Elaine P. Wynter, Catherine L. Martin, Bobbi L Hall, Dawn M. Gilbert, Karen M. Kuhn, Genevieve M. Mccarthy, Anne M. Venturi, Jena Bargon, Karen Coesens, Lynne V. Duguay, Barbara A. Sterne, Jill A. Schafer, Jill A. Webster, Katharina E. Smith, Mary K. Brown

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Thesis (Ph.D.)--University of Washington, 2016-06

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Rocks used as construction aggregate in temperate climates deteriorate to differing degrees because of repeated freezing and thawing. The magnitude of the deterioration depends on the rock's properties. Aggregate, including crushed carbonate rock, is required to have minimum geotechnical qualities before it can be used in asphalt and concrete. In order to reduce chances of premature and expensive repairs, extensive freeze-thaw tests are conducted on potential construction rocks. These tests typically involve 300 freeze-thaw cycles and can take four to five months to complete. Less time consuming tests that (1) predict durability as well as the extended freeze-thaw test or that (2) reduce the number of rocks subject to the extended test, could save considerable amounts of money. Here we use a probabilistic neural network to try and predict durability as determined by the freeze-thaw test using four rock properties measured on 843 limestone samples from the Kansas Department of Transportation. Modified freeze-thaw tests and less time consuming specific gravity (dry), specific gravity (saturated), and modified absorption tests were conducted on each sample. Durability factors of 95 or more as determined from the extensive freeze-thaw tests are viewed as acceptable—rocks with values below 95 are rejected. If only the modified freeze-thaw test is used to predict which rocks are acceptable, about 45% are misclassified. When 421 randomly selected samples and all four standardized and scaled variables were used to train aprobabilistic neural network, the rate of misclassification of 422 independent validation samples dropped to 28%. The network was trained so that each class (group) and each variable had its own coefficient (sigma). In an attempt to reduce errors further, an additional class was added to the training data to predict durability values greater than 84 and less than 98, resulting in only 11% of the samples misclassified. About 43% of the test data was classed by the neural net into the middle group—these rocks should be subject to full freeze-thaw tests. Thus, use of the probabilistic neural network would meanthat the extended test would only need be applied to 43% of the samples, and 11% of the rocks classed as acceptable would fail early.

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Polyethylcyanoacrylate (PECA) nanoparticles were prepared by interfacial polymerization of a water-in-oil microemulsion. Nanoparticles were isolated from the polymerization template by sequential ethanol washing and centrifugation. A nanocapsule preparation yielding the original particle size and distribution following redispersion in an aqueous solution was achieved by freeze-drying the isolated nanoparticles in a solution of 5% w/v sugar. The cytotoxicity and uptake of nanocapsules by dendritic cells was investigated using a murine-derived cell line (D1). PECA nanoparticles were found to adversely effect cell viability at concentrations greater than 10 mug/ml of polymer in the culture medium. In comparison to antigen in solution, cell uptake of antigen encapsulated within nanoparticles was significantly higher at both 4 and 37 degreesC. Following a 24 h incubation period, the percentage of cells taking-up antigen was also increased when antigen was encapsulated in nanoparticles as compared to antigen in solution. The uptake of nanoparticles and the effect of antigen formulation on morphological cell changes indicative of cell maturation were also investigated by scanning electron microscopy (SEM). SEM clearly demonstrated the adherence of nanoparticles to the cell surface. Incubation of D1 dendritic cells with nanoparticles containing antigen also resulted in morphological changes indicative of cell maturation similar to that observed when the cells were incubated with lipopolysaccharide. In contrast, cells incubated with antigen solution did not demonstrate such morphological changes and appeared similar to immature cells that had not been exposed to antigen.

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Direct continuity between the membranes of cisternae in the Golgi complex in mammalian cells rarely has been observed; when seen, its documentation has been equivocal. Here we have used dual-axis electron microscope tomography to examine the architecture of the Golgi in three dimensions at approximate to6-nm resolution in rapidly frozen, freeze-substituted murine cells that make and secrete insulin in response to glucose challenge. Our data show three types of direct connections between Golgi cisternae that are normally distinct from one another. These connections all bypass interceding cisternae. We propose that when pancreatic beta cells are stimulated to synthesize and secrete insulin rapidly in vivo, such connections provide a continuous lumen that facilitates the rapid transit of large amounts of newly made protein for secretion. The heterotypic fusion of cisternae, even transiently, raises important questions about the molecular mechanisms that (i) facilitate the fusion/fission of cisternal membranes and control the directionality and specificity of such events, and (it) retain Golgi processing enzymes at specific places within individual cisternae when two cisternae at different levels in the Golgi have fused, maintaining the sequential processing hierarchy that is a hallmark of Golgi organization.

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In an attempt to develop a gamete-recovery protocol for the northern hairy nosed wombat (Lasiorhinus krefftii), spermatozoa were removed from the cauda epididymides of four common wombats (Vombatus ursinus) and cryopreserved following a variety of prefreeze storage conditions. Spermatozoa stored for 72 h at 4 degrees C within the testicle before cryopreservation tolerated the freeze-thaw procedure remarkably well, resulting in a higher post-thaw viability (% motile P< 0.01; rate of movement P< 0.01; % live P< 0.01) than sperm recovered on the day of post-mortem, stored in a test tube for 72 h at 4 degrees C and then frozen. The effect of post-thaw dilution with Tris citrate fructose (TCF) diluent on the survival of epididymal common wombat spermatozoa was also investigated. Motility (P< 0.05), rate of sperm movement (P< 0.01) and the percentage of live spermatozoa (P< 0.05) were all significantly greater when spermatozoa were thawed and diluted immediately in TCF than when thawed without dilution. The present study also reports, for the first time, a successful pellet method of freezing wombat spermatozoa on dry ice; volumes of 0.25 and 0.5mL resulted in higher post- thaw survival compared with 0.1-mL pellets.

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The purpose of this study was to systematically investigate the effect of lipid chain length and number of lipid chains present on lipopeptides on their ability to be incorporated within liposomes. The peptide KAVYNFATM was synthesized and conjugated to lipoamino acids having acyl chain lengths of C-8, C-12 and C-16. The C-12 construct was also prepared in the monomeric, dimeric and trimeric form. Liposomes were prepared by two techniques: hydration of dried lipid films (Bangham method) and hydration of freeze-dried monophase systems. Encapsulation of lipopeptide within liposomes prepared by hydration of dried lipid films was incomplete in all cases ranging from an entrapment efficiency of 70% for monomeric lipoamino acids at a 5% (w/w) loading to less than 20% for di- and trimeric forms at loadings of 20% (w/w). The incomplete entrapment of lipopeptides within liposomes appeared to be a result of the different solubilities of the lipopeptide and the phospholipids in the solvent used for the preparation of the lipid film. In contrast, encapsulation of lipopeptide within liposomes prepared by hydration of freeze-dried monophase systems was high, even up to a loading of 20% (w/w) and was much less affected by the acyl chain length and number than when liposomes were prepared by hydration of dried lipid films. Freeze drying of monophase systems is better at maintaining a molecular dispersion of the lipopeptide within the solid phospholipid matrix compared to preparation of lipid film by evaporation, particularly if the solubility of the lipopeptide in solvents is markedly different from that of the polar lipids used for liposome preparation. Consequently, upon hydration, the lipopeptide is more efficiently intercalated within the phospholipid bilayers. (C) 2005 Elsevier B.V. All rights reserved.