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Articles 29911 - 29940 of 34568

Full-Text Articles in Physical Sciences and Mathematics

Application Of Environmental Organic Petrology And Geochemistry To Fingerprint Organic Pollutants In The Recent Sediments Of Lake Ontario, Prasanta K. Mukhopadhyay, Michael A. Kruge, C.F. Michael Lewis Jan 1997

Application Of Environmental Organic Petrology And Geochemistry To Fingerprint Organic Pollutants In The Recent Sediments Of Lake Ontario, Prasanta K. Mukhopadhyay, Michael A. Kruge, C.F. Michael Lewis

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Selected surface sediment samples (sediment depth 0-10 cm) collected in the Niagara basin (western Lake Ontario) were chosen for organic matter characterization using organic petrological and geochemical techniques normally reserved for the study of coal, petroleum source rock and crude oil. The study was performed to assess the effectiveness of these techniques in discriminating between natural and anthropogenic organic matter and to determine the extent of organic pollution of the lake sediments. The organic carbon contents of the samples vary from 1.5 to 3.5%, with upper layer (0-5 cm) samples have higher TOC values than those from the lower layer …

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Separation And Artificial Maturation Of Macerals From Type Ii Kerogen, Michael A. Kruge, Patrick Landais, David F. Bensley, B Artur Stankiewicz, Marcel Elie, Olivier Ruau Jan 1997

Separation And Artificial Maturation Of Macerals From Type Ii Kerogen, Michael A. Kruge, Patrick Landais, David F. Bensley, B Artur Stankiewicz, Marcel Elie, Olivier Ruau

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Immature Type II kerogen (HI= 660 mg/g) from the Lower Toarcian of the Paris Basin was separated into an alginite concentrate (HI = 952 mg/g) and an amorphous organic matter (AOM) concentrate (HI = 573 mg/g) by density centrifugation. The flash pyrolyzate of the alginite is characterized by high relative concentrations of several series of n-alkanones and n-alkenones (including mid-chain alkyl ketones), in addition to n-alkanes, n-alk-1-enes and n-alkadienes. To our knowledge, this Toarcian alginite is the oldest example of marine organic matter whose pyrolyzate contains mid-chain alkanones in such high relative concentrations. In sharp …

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Complexes Between Nascent Polypeptides And Their Molecular Chaperones In The Cytosol Of Mammalian Cells, Daryl K. Eggers, W. J. Welch, W. J. Hansen Jan 1997

Complexes Between Nascent Polypeptides And Their Molecular Chaperones In The Cytosol Of Mammalian Cells, Daryl K. Eggers, W. J. Welch, W. J. Hansen

Daryl K. Eggers

Folding of newly synthesized proteins in vivo is believed to be facilitated by the cooperative interaction of a defined group of proteins known as molecular chaperones. We investigated the direct interaction of chaperones with nascent polypeptides in the cytosol of mammalian cells by multiple methods. A new approach using a polyclonal antibody to puromycin allowed us to tag and capture a population of truncated nascent polypeptides with no bias as to the identity of the bound chaperones. In addition, antibodies that recognize the cytosolic chaperones hsp70, CCT (TRiC), hsp40, p48 (Hip), and hsp90 were compared on the basis of their …

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Carbon Monoxide Hydrogenation Over Ru-Mn-K/Al_2o_3 Catalysts, S. Tajammul Hussain, M. Ashraf Atta Jan 1997

Carbon Monoxide Hydrogenation Over Ru-Mn-K/Al_2o_3 Catalysts, S. Tajammul Hussain, M. Ashraf Atta

Turkish Journal of Chemistry

The catalytic behavior of a series Ru/Al_2O_3 catalysts promoted with various levels of Mn and K prepared by coimpregnation were investigated in the CO-hydrogenation reaction. Catalytic studies showed that the addition of Mn enhances the production of Fischer Tropsch products and K promotion in particular enhances the production of unsaturated hydrocarbons while inhibiting the methanation reaction. The influence of K and Mn on the Fischer Tropsch product selectivity in CO-hydrogenation studies is discussed in terms of ensemble and electronic effects, and the production of a new surface site Ru:Mn:K.

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Observation Of Upper Tropospheric Sulfur Dioxide- And Acetone-Pollution: Potential Implications For Hydroxyl Radical And Aerosol Formation, F. Arnold, J. Schneider, K. Gollinger, H. Schlager, P. Schulte, Donald E. Hagen, Philip D. Whitefield, Peter F. J. Van Velthoven Jan 1997

Observation Of Upper Tropospheric Sulfur Dioxide- And Acetone-Pollution: Potential Implications For Hydroxyl Radical And Aerosol Formation, F. Arnold, J. Schneider, K. Gollinger, H. Schlager, P. Schulte, Donald E. Hagen, Philip D. Whitefield, Peter F. J. Van Velthoven

Physics Faculty Research & Creative Works

Aircraft-based measurements of sulfur dioxide, acetone, carbon dioxide, and condensation nuclei (CN) were made over the north-eastern Atlantic at upper tropospheric altitudes, around 9000 m. On October 14, 1993, strong SO 2- and acetone-pollution (both up to 3 ppbv) were observed, which were accompanied by a CO 2-enhancement of up to 6 ppmv, and large CN-concentrations of up to about 1500 cm -3 (for radii ≥ 6 nm). CN, excess CO 2, and to a lesser degree also acetone, were positively correlated with SO 2. Air mass trajectory analyses indicate, that most of the air masses …

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Oxidative Reactions In Normal And Sickle Hemoglobin-Lipid Mixtures Under Various Conditions, Merita Nirmali Dias Jan 1997

Oxidative Reactions In Normal And Sickle Hemoglobin-Lipid Mixtures Under Various Conditions, Merita Nirmali Dias

Dissertations

No abstract provided.

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On-Road Co, Hc, No And Opacity Measurements (Presentation), Donald H. Stedman, Gary A. Bishop, Phillip Aldrete Jan 1997

On-Road Co, Hc, No And Opacity Measurements (Presentation), Donald H. Stedman, Gary A. Bishop, Phillip Aldrete

Fuel Efficiency Automobile Test Publications

No abstract provided.

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Analysis Of Mercury Coordination Environments Of Tridentate And Tetradentate Nitrogen Based Ligands By Nmr Spectroscopy And X-Ray Crystallography, Rachel E. Freer Jan 1997

Analysis Of Mercury Coordination Environments Of Tridentate And Tetradentate Nitrogen Based Ligands By Nmr Spectroscopy And X-Ray Crystallography, Rachel E. Freer

Dissertations, Theses, and Masters Projects

No abstract provided.

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Properties And Macromolecular Structure Of Unacetylated And Acetylated Nata De Coco, Ma. Assunta C. Cuyegkeng, Ma. Amy L. Dimalanta Jan 1997

Properties And Macromolecular Structure Of Unacetylated And Acetylated Nata De Coco, Ma. Assunta C. Cuyegkeng, Ma. Amy L. Dimalanta

Chemistry Faculty Publications

This study aims to gain more insight into the supramolecular structure of the cellulose in nata de coco, and to compare its ability to be modified with the known types of cellulose. The investigations were done using IR spectroscopy and thennal analysis. The IR spectra of microcrystalline cellulose were identical to cellulose spectra. However, those of dried nata de coco cellulose showed additional peaks that indicated a loss of inter- and intra-sheet hydrogen bonding, usually extensive in other cellulose forms where sheets are the prevalent secondary structures. This kind of structure would be consistent with the necessary framework for gel …

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Effects Of Perinatal Exposure To Cocaine On Sexually Differentiated Gonadotropin Regulation In Rats, Jihun M. Lee Jan 1997

Effects Of Perinatal Exposure To Cocaine On Sexually Differentiated Gonadotropin Regulation In Rats, Jihun M. Lee

Master's Theses

No abstract provided.

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The Effects Of Exercise Training On Resting Prostacyclin And Thromboxane A(2) In Older Adults, R D. Kauffman, G S. Sforzo, Blaise Frost, M K. Todd Jan 1997

The Effects Of Exercise Training On Resting Prostacyclin And Thromboxane A(2) In Older Adults, R D. Kauffman, G S. Sforzo, Blaise Frost, M K. Todd

Chemistry Faculty Publications

Ten adult volunteers participated in 16 weeks of cardiovascular exercise training (EG) to determine the effects of training on resting prostacyclin (PGI(2)) and thromboxane A(2) (TXA(2)). Six volunteers of similar age served as sedentary controls (CG). Blood was collected in tubes after training and eicosanoids were measured by standard I-125 RIA methods. Over the 16 weeks of the study, PGI(2) decreased 48% for EG and 33% for CG. There were no between-group differences for PGI(2) values. No significant within-group changes in TXA(2) were found, whereas between-group pretraining TXA(2) values were significantly different. A time main effect for PGI(2) may indicate …

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A Multinuclear Magnetic Resonance Study Of Cesium And Chloride Distribution In Human Erythrocyte Suspensions, Wanrong Lin Jan 1997

A Multinuclear Magnetic Resonance Study Of Cesium And Chloride Distribution In Human Erythrocyte Suspensions, Wanrong Lin

Dissertations

No abstract provided.

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Preparation Of Powder Precursors And Evaporation Of Photoconductive Indium Sulfide Films, Chris Barber, Robert Engelken, Brandon Kemp, Wasim Aleem, Imran Khan, Chris Edrington, Michael Buck, Clayton Workman, Anup Thapa, Tom Jakobs Jan 1997

Preparation Of Powder Precursors And Evaporation Of Photoconductive Indium Sulfide Films, Chris Barber, Robert Engelken, Brandon Kemp, Wasim Aleem, Imran Khan, Chris Edrington, Michael Buck, Clayton Workman, Anup Thapa, Tom Jakobs

Journal of the Arkansas Academy of Science

We have demonstrated significant photoconductance in indium sulfide thin films prepared by thermal vacuum evaporation ofIn2$3 powders synthesized in-house by chemical precipitation ofInCl3 or In(CH3COO)3, and (NH4)2S or Na2S. The Delta G lambda/Gdark values have been as high as 0.1 in the initial unoptimized films. Excess sulfur (via a mixture of polysulfide and sulfide ions in the synthesis bath) appears to be important in achieving reproducible and large photoconductivities. In2S3 is particularly attractive as a lower toxicity alternative to CdS in optoelectronic applications such as photovoltaic and photoconductive cells.

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Molecular Dynamics Of The Hammerhead Ribozyme, Vasant T. Gandhi Jan 1997

Molecular Dynamics Of The Hammerhead Ribozyme, Vasant T. Gandhi

Master's Theses

No abstract provided.

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The Application Of Matrix Assisted Laser Desorption Ionization Time Of-Flight Mass Spectrometry (Maldi Tof Ms) For Dna Adducts And Cross-Linked Hemoglobin Analysis, Xiaomei Gu Jan 1997

The Application Of Matrix Assisted Laser Desorption Ionization Time Of-Flight Mass Spectrometry (Maldi Tof Ms) For Dna Adducts And Cross-Linked Hemoglobin Analysis, Xiaomei Gu

Master's Theses

No abstract provided.

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Computational Studies Of Hydroboration: Remote Functional Groups And Ring Size Effects, Sarah Liberty Olbrich Jan 1997

Computational Studies Of Hydroboration: Remote Functional Groups And Ring Size Effects, Sarah Liberty Olbrich

Honors Theses

This study is a preliminary computational study of the energies of complex molecules. We are looking at the roles of remote heteroatoms in the hydroboration of propellane systems and ring size effects in the solvolysis of cyclic alkyl halides was examined using computational methods. Geometry and transition state optimizations were done using semi empirical (MNDO. AMI) and ab initio (STO-3G, 3-2IG, and 6-31G*) methods. Attempts to correlate computational results with previously reported data will be presented.

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Suspended Particulate Matter And Sediment Of Penobscot Estuary, Craig M. Pochini Jan 1997

Suspended Particulate Matter And Sediment Of Penobscot Estuary, Craig M. Pochini

Honors Theses

An automated scanning electron microscope with an energy dispersive spectrometer was used to gather morphological and chemical information on individual particles from the suspended particulate matter of the Penobscot Estuary and the sediment of Goose Cove/Pond. The goals of the Penobscot Estuary study were to investigate the transport of particles into and through an estuary, the speciation of elements, the abundance of heavy metals, and the background levels of heavy metals. The majority of particles were aluminosilicates originating from a riverine source. Heavy metals were not abundant in the Penobscot Estuary. The objectives of the Goose Cove/Pond study were to …

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Comparative Analysis Of Pesticide Extraction Methods, Julie A. Lapos Jan 1997

Comparative Analysis Of Pesticide Extraction Methods, Julie A. Lapos

Honors Theses, 1963-2015

Liquid-Liquid Extraction using methylene chloride, Liquid-Liquid extraction using a 75:25 mexanes: ethyl acetate solvent, and Solid Phase Extraction using C-18 disks were compared. Aliquots of water spiked with alachlor, atrazine, and trifluralin were extracted using each of the techniques. The extracts were concentrated and analyzed using Gas Chromatography/Mass Spectrometer with Selected Ion Monitoring. A surrogate, 2-nitro-m-xlene, and an internal standard, phenanthrene-d10,, were used. At spiking levels of 5-60 ug/L, there was not a significant statistical difference between the three methods when the liquid extractors were run for 24 hours. There was however a difference between the solid phase extraction and …

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Complexes Between Nascent Polypeptides And Their Molecular Chaperones In The Cytosol Of Mammalian Cells, Daryl K. Eggers, W. J. Welch, W. J. Hansen Jan 1997

Complexes Between Nascent Polypeptides And Their Molecular Chaperones In The Cytosol Of Mammalian Cells, Daryl K. Eggers, W. J. Welch, W. J. Hansen

Faculty Publications, Chemistry

Folding of newly synthesized proteins in vivo is believed to be facilitated by the cooperative interaction of a defined group of proteins known as molecular chaperones. We investigated the direct interaction of chaperones with nascent polypeptides in the cytosol of mammalian cells by multiple methods. A new approach using a polyclonal antibody to puromycin allowed us to tag and capture a population of truncated nascent polypeptides with no bias as to the identity of the bound chaperones. In addition, antibodies that recognize the cytosolic chaperones hsp70, CCT (TRiC), hsp40, p48 (Hip), and hsp90 were compared on the basis of their …

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Synthesis Of An Organophosphorus Analog Of Acetylcholine, Darshan Mehta '97 Jan 1997

Synthesis Of An Organophosphorus Analog Of Acetylcholine, Darshan Mehta '97

Honors Projects

Acetylcholinesterase (AChE) is an important enzyme in our nervous system In normal nerve function, AChE catalyzes the hydrolysis of acetylcholine (ACh) into its respective components, choline and acetate. Recent interest has been focused on AChE because of its potential role in the pathology of neurodegenerative diseases such as Alzheimer's disease. Studies have revealed that the active site of AChE contains an esteratic and several hydrophobic/anionic subsites. AChE is inhibited by organophosphorus (OP) compounds like sarin and soman. As a result, OP compounds have been used to study the structure of AChE and the mechanism by which it catalyzes the hydrolysis …

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Immunologic And Hematopoietic Effects Of Cd40 Stimulation After Syngeneic Bone Marrow Transplantation In Mice, Satoshi Funakoshi, Dennis D. Taub, Miriam R. Anver, Arati Raziuddin, Osamu Asai, Prakash Reddy, Helen C. Rager, William C. Fanslow, Dan L. Longo, William J. Murphy Jan 1997

Immunologic And Hematopoietic Effects Of Cd40 Stimulation After Syngeneic Bone Marrow Transplantation In Mice, Satoshi Funakoshi, Dennis D. Taub, Miriam R. Anver, Arati Raziuddin, Osamu Asai, Prakash Reddy, Helen C. Rager, William C. Fanslow, Dan L. Longo, William J. Murphy

Chemistry Faculty Research & Creative Works

CD40 is a molecule present on multiple cell types including B lymphocyte lineage cells. CD40 has been shown to play an important role in B cell differentiation and activation in vitro, although little is known concerning the effects of CD40 stimulation in vivo. We therefore examined the effects of CD40 stimulation in mice using a syngeneic bone marrow transplantation (BMT) model in an effort to augment B cell recovery after high dose therapy with hematopoietic reconstitution. After the BMT, mice were treated with or without 2-6 μg of a soluble recombinant murine CD40 ligand (srmCD40L) given intraperitoneally twice a week. …

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Solvent Impregnated Resins For The Recovery Of Gold From Gold(I)Thiourea Solutions, Fiona Fitzpatrick Jan 1997

Solvent Impregnated Resins For The Recovery Of Gold From Gold(I)Thiourea Solutions, Fiona Fitzpatrick

Masters

Solvent Impregnated Resins (SIRs) are high surface area, macroporous, polymeric resins which have been physically impregnated with an organic solvent. In this research, three resins have been impregnated with Di-2-ethylhexyl phosphoric acid, a solvent which has shown selectivity to gold. The ability of the resins to recover gold (1) thiourea perchlorate from solution has been investigated. The resins have been studied both bare and when impregnated with the solvent and their efficiency was seen to increase upon impregnation. The overall efficiency of the resins was found to be pH dependent. It is also related to the level of impregnation of …

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Organic Carbon Abundance, Distribution And Metabolism At The Oyster, Virginia Study Site, Elizabeth Canuel, Iris C. Anderson, Craig Tobias Jan 1997

Organic Carbon Abundance, Distribution And Metabolism At The Oyster, Virginia Study Site, Elizabeth Canuel, Iris C. Anderson, Craig Tobias

Reports

This report describes a pilot study conducted at the DOE Subsurface Science Program's study site in Oyster, VA. The objective of this study was to examine whether 2 organic matter associated with the solid and dissolved phases was labile enough to support microbial activity. Organic matter availability was assessed in two ways: (1) by quantifying the amount and distribution of total organic carbon (TOC) associated with the solid phase and (2) laboratory experiments to examine the utilization of dissolved organic matter by measuring total microbial respiration. In addition to assessing total respiration, we specifically addressed organic matter respiration via denitrification. …

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Photothermal Lens Spectrometry Of Homogeneous Fluids With Incoherent White‐Light Excitationusing A Cylindrical Sample Cell, Agnes Chartier, Stephen E. Bialkowski Jan 1997

Photothermal Lens Spectrometry Of Homogeneous Fluids With Incoherent White‐Light Excitationusing A Cylindrical Sample Cell, Agnes Chartier, Stephen E. Bialkowski

Stephen E. Bialkowski

A model for photothermal lens signal generation in a cylindrical sample cell under constant irradiance excitation is described and tested. The model is developed with and without the assumption that the sample cell does not change temperature over the irradiation time. In both cases, the photothermal lens is predicted to be parabolic in form with a strength that is independent of sample cell radius. The predicted irradiance independence suggests that incoherent illumination can be used to perform photothermal lens spectroscopy in low-volume cells. Experimental evidence is obtained using a Xe arc lamp to perform photothermal lens spectroscopy in a 6 …

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Diffraction Effects In Single‐ And Two‐Laser Photothermal Lens Spectroscopy, Stephen E. Bialkowski, Agnes Chartier Jan 1997

Diffraction Effects In Single‐ And Two‐Laser Photothermal Lens Spectroscopy, Stephen E. Bialkowski, Agnes Chartier

Stephen E. Bialkowski

A simple method for calculating the effects of optical geometry on photothermal lens signals is shown. This method is based on calculating cumulative electric-field phase shifts produced by a series of Gaussian refractive-index perturbations produced by the photothermal effect. Theoretical results are found for both pulsed-laser and continuous Gaussian laser excitation sources and both single- and two-laser apparatuses commonly employed in photothermal lens spectroscopy. The effects of apparatus geometry on the resulting signal are shown. Analytical time-dependent signal results are found for small signals. Analytical pump–probe focus geometry results allow direct optimization for certain conditions. The calculations indicate that the …

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The Synthesis Of Benzophenone-3,5-Diacid Chloride For The Double Capping Of Beta-Cyclodextrin, Clyde Wesley Eargle Jan 1997

The Synthesis Of Benzophenone-3,5-Diacid Chloride For The Double Capping Of Beta-Cyclodextrin, Clyde Wesley Eargle

Dissertations, Theses, and Masters Projects

No abstract provided.

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Microstructures Of Poly(Vinyl Acetate) Studied By Nuclear Magnetic Resonance Spectroscopy, Hongyang Yao Jan 1997

Microstructures Of Poly(Vinyl Acetate) Studied By Nuclear Magnetic Resonance Spectroscopy, Hongyang Yao

Dissertations, Theses, and Masters Projects

Carbon-13 NMR spectroscopy was used to investigate the microstructures of poly(vinyl acetate) prepared by solution polymerization in benzene. A series of aromatic compounds was synthesized in order to model the structures formed via chain transfer to solvent. The peaks near 126.5 and 128.5 ppm in the spectra of the polymer samples were assigned to a 1-phenyl-(2n + 1)-multi-acetoxyalkane (where n = 1, 2, 3, etc.) microstructure. The concentration of that structure obtained from NMR spectra was correlated with the concentration calculated from reported kinetic data.;Chain transfer to benzene was shown to occur by addition of the macroradical to benzene, followed …

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A Study Of Poly(Vinyl Chloride) Microstructure, Vadim Guennadievich Zaikov Jan 1997

A Study Of Poly(Vinyl Chloride) Microstructure, Vadim Guennadievich Zaikov

Dissertations, Theses, and Masters Projects

High-field {dollar}\sp{lcub}13{rcub}{dollar}C and {dollar}\sp1{dollar}H NMR spectroscopies were used to investigate some unusual features of the molecular microstructure of poly(vinyl chloride) (PVC).;Several model monochloroalkenes were synthesized in order to determine {dollar}\sp{lcub}13{rcub}{dollar}C shift increments for the replacement of H by Cl at positions that are near an isolated internal double bond. These increments then were used to predict the {dollar}\sp{lcub}13{rcub}{dollar}C shifts of the internal allylic chloride structure in PVC. The predictions were not satisfactory, because, as expected, the increments were not additive.;It was shown that during conventional VC polymerization, the chloroallylic chain end (-CH{dollar}\sb2{dollar}CH=CHCH{dollar}\sb2{dollar}Cl) does not copolymerize with the monomer and is …

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Directed Panspermia. 3. Strategies And Motivations For Seeding Star-Forming Clouds, Michael Noah Mautner Jan 1997

Directed Panspermia. 3. Strategies And Motivations For Seeding Star-Forming Clouds, Michael Noah Mautner

Chemistry Publications

Microbial swarms aimed at star-forming regions of interstellar clouds can seed stellar associations of 10 - 100 young planetary systems. Swarms of millimeter size, milligram packets can be launched by 35 cm solar sails at 5E-4 c, to penetrate interstellar clouds. Selective capture in high-density planetary accretion zones of densities > 1E-17 kg m-3 is achieved by viscous drag. Strategies are evaluated to seed dense cloud cores, or individual protostellar condensations, accretion disks or young planets therein. Targeting the Ophiuchus cloud is described as a model system. The biological content, dispersed in 30 μm, 1E-10 kg capsules of 1E6 freeze-dried microorganisms …

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Efficient And General Synthesis Of Novel Β-Polyfluoroalkoxy Vinamidinium Salts, Koichiro Kase, Mitsuyoshi Katayama, Takashi Ishihara, Hiroki Yamanaka, John T. Gupton Jan 1997

Efficient And General Synthesis Of Novel Β-Polyfluoroalkoxy Vinamidinium Salts, Koichiro Kase, Mitsuyoshi Katayama, Takashi Ishihara, Hiroki Yamanaka, John T. Gupton

Chemistry Faculty Publications

Novel β-polyfluoroalkoxy vinamidinium salts 3 and/or 4 were synthesized in good yields by the reaction of N-(2- polyfluoroalkoxy-3 ,3-difluoro-1-propenyI)trimethylammonium iodides (2), prepared from N-(2,3,3-trifluoro-1-propenyl)trimethylammonium iodide (1), with secondary amines in MeCN at 70 °C for 1 h. The salts were also obtainable in comparable yields by the one-pot reaction of 1 with sodium polyfluoroalkoxide followed by treatment with amines.

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