62 results on '"S. Clawson"'
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2. Linear Covariance Model Development for Target Engagements
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Jeffrey S. Clawson and Randy Christensen
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Development (topology) ,Computer science ,Econometrics ,Covariance model - Published
- 2021
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3. Surveillance of biting midges (Culicoides spp.) in Northern Ireland: influence of seasonality, surrounding habitat and livestock housing
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A. W. Gordon, I. Rea, S. Jess, A. K. Murchie, G. M. Thompson, I. W. N. Forsythe, and S. Clawson
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Serotype ,Veterinary medicine ,General Veterinary ,biology ,Ceratopogonidae ,040301 veterinary sciences ,business.industry ,030231 tropical medicine ,Outbreak ,04 agricultural and veterinary sciences ,Woodland ,Seasonality ,Culicoides ,biology.organism_classification ,medicine.disease ,0403 veterinary science ,03 medical and health sciences ,0302 clinical medicine ,Habitat ,Insect Science ,medicine ,Parasitology ,Livestock ,business ,Ecology, Evolution, Behavior and Systematics - Abstract
Biting midges, Culicoides spp. (Diptera: Ceratopogonidae), are important vectors of viral pathogens. Following the outbreak of bluetongue serotype 8 in Europe between 2006 and 2009, many Culicoides surveillance programmes were initiated to identify vector-active periods, in accordance with European Commission regulation 2007/1266/EC. This study utilized surveillance data from 4 years of continuous light-trapping at 14 sites in Northern Ireland. The number of captured Culicoides varied from none during the vector-free period (December–April) to more than 36 000 per night during peak activity in the summer. The Obsoletus group represented 75% of Culicoides collected and the Pulicaris group represented 21%. A total of 91% of Culicoides were female, of which 42% were parous. Abundance data, sex ratios and parous rates suggested that both the Obsoletus and Pulicaris groups underwent three generations/year. The Obsoletus group was associated with cattle-rearing habitats and woodland, the Impunctatus group was found in habitats related to sheep rearing and the Pulicaris group were associated with both cattle and sheep. Housing did not reduce incursion of female Obsoletus group Culicoides but it did for males and for the Pulicaris group Culicoides. The influence of housing was strongly affected by time of year, probably reflecting the presence of livestock indoors/outdoors.
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- 2017
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4. DEET (N,N-diethyl-meta-toluamide)/PMD (para-menthane-3,8-diol) repellent-treated mesh increases Culicoides catches in light traps
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I. Rea, S. Jess, A. W. Gordon, S. Clawson, I. W. N. Forsythe, and A. K. Murchie
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0301 basic medicine ,Insecticides ,030231 tropical medicine ,Phenylcarbamates ,DEET ,Bendiocarb ,Cyclohexane Monoterpenes ,Common method ,Ceratopogonidae ,Bluetongue ,Toxicology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Nitriles ,Pyrethrins ,Animals ,Volume concentration ,Sheep ,General Veterinary ,biology ,Plant Extracts ,Terpenes ,fungi ,General Medicine ,Limiting ,030108 mycology & parasitology ,biology.organism_classification ,Culicoides ,Insect Vectors ,Menthol ,Infectious Diseases ,chemistry ,Insect Repellents ,Insect Science ,Midge ,Parasitology ,p-Menthane-3,8-diol - Abstract
Biting midges (Culicoides spp.) are vectors of bluetongue and Schmallenberg viruses. Treatment of mesh barriers is a common method for preventing insect-vectored diseases and has been proposed as a means of limiting Culicoides ingression into buildings or livestock transporters. Assessments using animals are costly, logistically difficult and subject to ethical approval. Therefore, initial screening of test repellents/insecticides was made by applying treatments to mesh (2 mm) cages surrounding Onderstepoort light traps. Five commercial treatments were applied to cages as per manufacturers' application rates: control (water), bendiocarb, DEET/p-menthane-3,8-diol (PMD) repellent, Flygo (a terpenoid based repellent) and lambda-cyhalothrin. The experimental design was a 5 × 5 Latin square, replicated in time and repeated twice. Incongruously, the traps surrounded by DEET/PMD repellent-treated mesh caught three to four times more Obsoletus group Culicoides (the commonest midge group) than the other treatments. A proposed hypothesis is that Obsoletus group Culicoides are showing a dose response to DEET/PMD, being attracted at low concentrations and repelled at higher concentrations but that the strong light attraction from the Onderstepoort trap was sufficient to overcome close-range repellence. This study does not imply that DEET/PMD is an ineffective repellent for Culicoides midges in the presence of an animal but rather that caution should be applied to the interpretation of light trap bioassays.
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- 2016
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5. Analysis of unstable degradation impurities of a benzodiazepine and their quantification without isolation using multiple linear regression
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John M. Campbell, Andy M. Wolters, Jacalyn S. Clawson, Simon A. Watson, Kevin L. Facchine, John J. Peterson, Benoît Igne, Jeremy A. Barry, Kaitie Grinias, and Kevin Leach
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Chromatography ,010405 organic chemistry ,Chemistry ,010401 analytical chemistry ,Clinical Biochemistry ,Pharmaceutical Science ,Models, Theoretical ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Benzodiazepines ,Drug Stability ,Impurity ,Drug Discovery ,Linear regression ,Forced degradation ,Multivariate Analysis ,Linear Models ,Degradation (geology) ,Multiple linear regression analysis ,Drug Contamination ,Spectroscopy ,Chromatography, High Pressure Liquid - Abstract
This manuscript presents a novel methodology for calculating the relative response factors (RRFs) of unstable degradation impurities of molibresib (1). The degradation impurities were observed by HPLC during stress testing and were accompanied by large mass balance deficits. However, the impurities could not be isolated for traditional RRF determination due to their instability. The RRFs of two degradation impurities were determined without isolation by multiple linear regression analysis of HPLC-UV data. The results permitted accurate quantification of the degradants. The benefits and drawbacks of the approach are discussed, including suggested validation acceptance criteria.
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- 2019
6. The Degradation Chemistry of GSK2879552: Salt Selection and Microenvironmental pH Modulation to Stabilize a Cyclopropyl Amine
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Sarah Bethune, Leanda Kindon, John M. Campbell, Mei Lee, Sonya Kennedy-Gabb, Ashley Janiga, Jacalyn S. Clawson, and Kevin Leach
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chemistry.chemical_classification ,Cyclopropanes ,Chemistry ,Chemistry, Pharmaceutical ,Hydrolysis ,Pharmaceutical Science ,Salt (chemistry) ,Hydrogen-Ion Concentration ,Combinatorial chemistry ,Benzoates ,Excipients ,Drug Stability ,Models, Chemical ,Solubility ,Impurity ,Molecule ,Degradation (geology) ,Moiety ,Chemical stability ,Amine gas treating ,Degradation pathway - Abstract
The cyclopropyl amine moiety in GSK2879552 (1) degrades hydrolytically in high pH conditions. This degradation pathway was observed during long-term stability studies and impacted the shelf life of the drug product. This article describes the work to identify the degradation impurities, elucidate the degradation mechanism, and design a stable drug product. It was found that salt selection and control of the microenvironmental pH of the drug product formulation blend significantly improved the chemical stability of the molecule in the solid state.
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- 2018
7. Rivaroxaban in antiphospholipid syndrome (RAPS) protocol: a prospective, randomized controlled phase II/III clinical trial of rivaroxaban versus warfarin in patients with thrombotic antiphospholipid syndrome, with or without SLE
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Hannah Cohen, Caroline J Doré, S Clawson, Munther A. Khamashta, David A. Isenberg, Beverley J. Hunt, and N Muirhead
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Male ,medicine.medical_specialty ,venous thromboembolism ,law.invention ,Fibrin Fibrinogen Degradation Products ,Special Article ,Rivaroxaban ,systemic lupus erythematosus ,Rheumatology ,Randomized controlled trial ,Quality of life ,Recurrence ,Antiphospholipid syndrome ,law ,Internal medicine ,medicine ,Humans ,Lupus Erythematosus, Systemic ,International Normalized Ratio ,Prospective Studies ,cardiovascular diseases ,Prospective cohort study ,Blood coagulation test ,business.industry ,Thrombin ,Warfarin ,Anticoagulants ,Antiphospholipid Syndrome ,medicine.disease ,Surgery ,warfarin ,Clinical trial ,thrombin generation ,Quality of Life ,Female ,Blood Coagulation Tests ,business ,Factor Xa Inhibitors ,medicine.drug - Abstract
Introduction The current mainstay of the treatment of thrombotic antiphospholipid syndrome (APS) is long-term anticoagulation with vitamin K antagonists (VKAs) such as warfarin. Non-VKA oral anticoagulants (NOACs), which include rivaroxaban, have been shown to be effective and safe compared with warfarin for the treatment of venous thromboembolism (VTE) in major phase III prospective, randomized controlled trials (RCTs), but the results may not be directly generalizable to patients with APS. Aims The primary aim is to demonstrate, in patients with APS and previous VTE, with or without systemic lupus erythematosus (SLE), that the intensity of anticoagulation achieved with rivaroxaban is not inferior to that of warfarin. Secondary aims are to compare rates of recurrent thrombosis, bleeding and the quality of life in patients on rivaroxaban with those on warfarin. Methods Rivaroxaban in antiphospholipid syndrome (RAPS) is a phase II/III prospective non-inferiority RCT in which eligible patients with APS, with or without SLE, who are on warfarin, target international normalized ratio (INR) 2.5 for previous VTE, will be randomized either to continue warfarin (standard of care) or to switch to rivaroxaban. Intensity of anticoagulation will be assessed using thrombin generation (TG) testing, with the primary outcome the percentage change in endogenous thrombin potential (ETP) from randomization to day 42. Other TG parameters, markers of in vivo coagulation activation, prothrombin fragment 1.2, thrombin antithrombin complex and D-dimer, will also be assessed. Discussion If RAPS demonstrates i) that the anticoagulant effect of rivaroxaban is not inferior to that of warfarin and ii) the absence of any adverse effects that cause concern with regard to the use of rivaroxaban, this would provide sufficient supporting evidence to make rivaroxaban a standard of care for the treatment of APS patients with previous VTE, requiring a target INR of 2.5.
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- 2015
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8. An adaptive spiking neural controller for flapping insect-scale robots
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Terrence C. Stewart, Chris Eliasmith, Taylor S. Clawson, and Silvia Ferrari
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Spiking neural network ,0209 industrial biotechnology ,Adaptive control ,Computer science ,020208 electrical & electronic engineering ,02 engineering and technology ,Power budget ,Flight test ,Power (physics) ,020901 industrial engineering & automation ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,Robot ,Flapping - Abstract
Insect-scale flapping robots are challenging to stabilize due to their fast dynamics, unmodeled parameter variations, and the periodic nature of their control input. Effective controller designs must tolerate wing asymmetries that occur due to manufacturing errors and react quickly to stabilize the fast unstable modes of the system. Additionally, they should have minimal power requirements to fit within the tightly constrained power budget associated with insect-scale flying robots. Adaptive control methods are capable of learning online to account for uncertain physical parameters and other model uncertainties, and can thus improve system performance over time. In this work, a spiking neural network is used to stabilize hovering of an insect-scale robot in the presence of unknown parameter variations. The controller is shown to adapt rapidly during a simulated flight test and requires a total of only 800 neurons, allowing it to be implemented with minimal power requirements.
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- 2017
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9. A blade element approach to modeling aerodynamic flight of an insect-scale robot
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Taylor S. Clawson, Sawyer B. Fuller, Silvia Ferrari, and Robert J. Wood
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030110 physiology ,0301 basic medicine ,Engineering ,Wing ,Scale (ratio) ,business.industry ,Aerodynamics ,01 natural sciences ,010305 fluids & plasmas ,Blade element theory ,Aerodynamic force ,03 medical and health sciences ,0103 physical sciences ,Flapping ,Robot ,Aerospace engineering ,business ,Actuator - Abstract
Recent manufacturing advances have allowed for the creation of gram and sub-gram insect-scale flapping robots. Most dynamic models of such robots to date have either assumed stroke-averaged forces or did not account for body motion. In order to design more robust and capable control methods, this paper incorporates blade element theory with a rigid-body dynamic model to calculate instantaneous aerodynamic forces during each wing stroke. As a result, the model accurately predicts body motions during flight.
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- 2017
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10. Spiking neural network (SNN) control of a flapping insect-scale robot
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Robert J. Wood, Taylor S. Clawson, Sawyer B. Fuller, and Silvia Ferrari
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Spiking neural network ,0209 industrial biotechnology ,Engineering ,Robot kinematics ,Quantitative Biology::Neurons and Cognition ,business.industry ,Control engineering ,RoboBee ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Robot control ,Computer Science::Robotics ,020901 industrial engineering & automation ,Hebbian theory ,Control theory ,Robot ,Flapping ,0210 nano-technology ,business ,Simulation - Abstract
The flapping microrobot known as RoboBee is the first robot to demonstrate insect-scale flight, as well as the most capable flying robotic insect to date. Controlled hover, trajectory-following, and perching have been accomplished by means of onboard sensors and actuators fabricated with the robot using a “pop-up book MEMS” process based on smart composite microstructures. This paper presents a RoboBee bio-inspired controller that closes the loop between the onboard sensors and actuators by means of a leaky integrate-and-fire spiking neural network that adapts in flight using a reward-modulated Hebbian plasticity mechanism.
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- 2016
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11. Structural Changes in the SNARE Protein SNAP&25 by PH and Ionic Strength
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Timothy T. Harris, Katrina J. Welker, Dixon J. Woodbury, Kara L. Woodbury, David Hallan, and Kyle S. Clawson
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Circular dichroism ,Crystallography ,Ionic strength ,Chemistry ,Beta sheet ,Biophysics ,bacteria ,Protein quaternary structure ,Protein secondary structure ,environment and public health ,Alpha helix ,Random coil ,Exocytosis - Abstract
The SNARE protein SNAP-25 plays a critical role in neuronal exocytosis by providing 2 of the 4 helical regions (SNARE domains) that form a coiled-coil quaternary structure. SNAP-25B contains four cysteines, one tryptophan, and one tyrosine all found in the linker region. Using Circular Dichroism to measure the secondary structure of SNAP-25B, we observe significant structural changes with pH and ionic strength. Three fundamental structures are observed: alpha helix, random coil, and beta sheet. The alpha helix and random coil have been observed previously, but the beta sheet (which is red-shifted to ∼229nm) is observed at pH5.5 and >75mM salt (NaF). The beta-sheet is reversibly changed into alpha helix at pH9. Using the fluorescent signal from tryptophan and tyrosine, an increase in pH reversibly changes the peak emission with a pK of ∼8.5, similar to the expected pKa for the sulfhydryl of cysteine. Replacing all cysteines with serines prevents this shift. The conformational changes observed above may lead to a change in accessibility of the 4 cysteines in SNAP-25B linker. Consistent with this hypothesis, we observe that decreasing ionic strength varies the number of cysteines accessible for labeling with a Biotin-maleimide tag technique developed in our lab (Woodbury et al., 2011. Anal. Biochem. 417:165-173). These data support the hypothesis that the structure of SNAP-25B is sensitive to ionic strength and pH, which may contribute to modulation of exocytosis in vivo.
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- 2016
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12. Adenoviruses in Fecal Samples from Asymptomatic Rhesus Macaques, United States
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James M. Wilson, David S. Clawson, Soumitra Roy, Arbansjit Sandhu, and Angelica Medina
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Epidemiology ,viruses ,Adenoviridae Infections ,lcsh:Medicine ,Polymerase Chain Reaction ,Genome ,law.invention ,Feces ,law ,Zoonoses ,stool ,Phylogeny ,Polymerase chain reaction ,Subclinical infection ,Transmission (medicine) ,macaque ,Monkey Diseases ,adenovirus ,polymerase ,Diarrhea ,PCR ,Infectious Diseases ,subclinical infection ,medicine.symptom ,fiber ,Microbiology (medical) ,rhesus ,macaques ,hexon ,Molecular Sequence Data ,Biology ,Asymptomatic ,lcsh:Infectious and parasitic diseases ,monkeys ,fecal samples ,medicine ,asymptomatic ,Animals ,Humans ,lcsh:RC109-216 ,Amino Acid Sequence ,Research ,lcsh:R ,DNA ,Sequence Analysis, DNA ,Macaca mulatta ,Virology ,United States ,DNA, Viral ,Adenoviruses, Simian ,Sequence Alignment - Abstract
Isolates contained fiber genes similar to those of adenovirus strains that cause infectious diarrhea in humans., Adenoviruses can cause infectious diarrheal disease or respiratory infections in humans; 2 recent reports have indicated probable human infection with simian adenoviruses (SAdVs). To assess the possibility of animal-to-human transmission of SAdVs, we tested fecal samples from asymptomatic rhesus macaques housed in 5 primate facilities in the United States and cultured 23 SAdV isolates. Of these, 9 were purified and completely sequenced; 3 SAdV samples from the American Type Culture Collection (SAdV-6, SAdV-18, and SAdV-20) were also completely sequenced. The sequence of SAdV-18 was closely related to that of human adenovirus F across the whole genome, and the new isolates were found to harbor 2 fiber genes similar to those of human adenovirus (HAdV) strains HAdV-40 and HAdV-41, which can cause infectious diarrhea. The high prevalence of adenoviruses in fecal samples from asymptomatic rhesus macaques and the similarity of the isolates to human strains indicates the possibility of animal-to-human transmission of SAdVs.
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- 2012
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13. A Systematic Method Development Strategy for Quantitative Color Measurement in Drug Substances, Starting Materials, and Synthetic Intermediates
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Alireza S. Kord, Leon Zhou, John T. Dougherty, Patricia-Ann Overstreet, Frederick G. Vogt, and Jacalyn S. Clawson
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Engineering drawing ,Engineering ,Flowchart ,Process (engineering) ,business.industry ,media_common.quotation_subject ,Pharmaceutical Science ,Color space ,Visual appearance ,computer.software_genre ,law.invention ,law ,Drug Discovery ,Critical to quality ,Key (cryptography) ,Quality (business) ,Color measurement ,Data mining ,business ,computer ,media_common - Abstract
The color of active pharmaceutical ingredients (APIs) can be a critical quality attribute for pharmaceutical products. Color variation can be indicative of contaminants, chemical impurities, solid-state form impurities, or degradation products. The color of the pharmaceutical materials is typically specified and determined using visual appearance testing. To avoid the inherent subjectivity of visual appearance testing, to understand the link between the color and the process parameters, and to facilitate quality agreements between customers and vendors of chemical starting materials, quantitative color measurements utilizing visible spectroscopic methods are increasingly needed. In this work, a systematic method development strategy (MDS) is described to assist with the development of robust and rugged quantitative color measurement methods based on a science- and risk-based approach aligned with quality-by-design principles. The MDS is illustrated using typical scenarios encountered in method development through several examples including a method developed for 2,3-dimethyl-2H-indazol-6-amine, a starting material in the commercial synthesis of pazopanib hydrochloride API. Flowcharts and examples are presented to illuminate key decision points in the MDS process including selection of (1) solution-state versus solid-state spectroscopic method, (2) optimal color space for reporting color measurement results, and (3) appropriate method risk assessment and control to ensure successful method implementation. General guidance is also provided to facilitate the discussion for setting quantitative color specifications.
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- 2011
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14. The Handbook for Teaching Leadership: Knowing, Doing & BeingThe Handbook for Teaching Leadership: Knowing, Doing & Being, edited by SnookScott A., KhuranaRakesh, and NohriaNitin. Thousand Oaks, CA: SAGE. Forthcoming October 2011. 917 pages. E-book option
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James G. S. Clawson
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Organizational Behavior and Human Resource Management ,Sociology ,Education - Published
- 2011
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15. Ab Initio Study of Hydrogen Storage in Water Clathrates
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Susan B. Rempe, Jacalyn S. Clawson, Randall T. Cygan, Kevin Leung, and Todd M. Alam
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Computational Mathematics ,Hydrogen storage ,Chemistry ,Ab initio ,Physical chemistry ,General Materials Science ,General Chemistry ,Electrical and Electronic Engineering ,Condensed Matter Physics - Published
- 2010
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16. Structural analysis of 5-fluorouracil and thymine solid solutions
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Manisha Chavda, Jacalyn S. Clawson, Frederick G. Vogt, Maria E. Barnett, Mark Strohmeier, and Joseph A. Vena
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education.field_of_study ,Lattice energy ,Chemistry ,Organic Chemistry ,Population ,Analytical Chemistry ,Thymine ,Inorganic Chemistry ,Crystallography ,chemistry.chemical_compound ,Solid-state nuclear magnetic resonance ,Heteronuclear molecule ,Density functional theory ,education ,Spectroscopy ,Powder diffraction ,Solid solution - Abstract
Solid-state analysis with powder X-ray diffraction (PXRD), solid-state NMR (SSNMR), and other spectroscopic and physical methods can provide detailed structural information about organic and pharmaceutical cocrystals. In this study, a range of solid-state analysis methods are used to characterize co-crystallized solid solutions of 5-fluorouracil and thymine. 1H, 13C and 19F SSNMR and PXRD methods are used to study the structure and disorder present in a solid solution previously prepared by solution evaporation methods; here the solid solution is prepared over a wider stoichiometric range by solvent-drop grinding techniques. Long-range perturbations of key chemical shifts are detectable by SSNMR, indicating that the solid solution is not random. Cross-polarization and heteronuclear correlation SSNMR experiments between 1H, 13C, and 19F nuclei offer insight into the structure of this solid solution, and density functional theory (DFT) methods are applied to calculate lattice energies and NMR properties in order to understand the population of the two primary disordered sites in the crystal structure. In addition, a second solid solution of 5-fluorouracil and thymine is reported and analyzed. This solid solution, which was produced by solvent-drop grinding experiments and characterized by SSNMR and powder X-ray diffraction methods, is determined to be an isostructural phase to that of anhydrous thymine with the inclusion of 5-fluorouracil defects. A similar effect does not occur under excess 5-fluorouracil conditions; instead, phase-separated Form 1 of 5-fluorouracil and anhydrous thymine are obtained. DFT calculations are applied to offer a possible explanation for this disparity.
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- 2009
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17. Process Development for A Novel Pleuromutilin-Derived Antibiotic
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Frederick G. Vogt, Yemane W. Andemichael, Sonja Sharpe, Lori Wernersbach, Susan V. Downing, Daniel B. Patience, Julie Tsui, Peng Liu, Lynette M. Oh, Wenning Dai, Jacalyn S. Clawson, Leon Zhou, James T. Wertman, Alan J. Freyer, Joseph Sisko, Jun Chen, Jun Wang, Edward C. Webb, and Diederich Ann M
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chemistry.chemical_compound ,Stereochemistry ,Chemistry ,Process development ,Organic Chemistry ,Physical and Theoretical Chemistry ,Combinatorial chemistry ,Pleuromutilin - Abstract
A scalable synthesis of a novel pleuromutilin-based antibiotic is reported. The synthesis features the scale-up of an interesting skeletal rearrangement of the pleuromutilin core and isolation of a highly purified product despite starting with relatively impure pleuromutilin. The use of Design of Experiment (DoE) and Principal Component Analysis (PCA) tools to achieve these goals is also discussed. Furthermore, the novel coupling of a carbamate and N-acyl-imidazole to produce the imidodicarbonate portion of the target molecule is described.
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- 2009
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18. Solid-State NMR Analysis of Organic Cocrystals and Complexes
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Simon A. Watson, Mark Strohmeier, Andrew J. Edwards, Tran N. Pham, Jacalyn S. Clawson, and Frederick G. Vogt
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Diffraction ,Stereochemistry ,Chemistry ,Hydrogen bond ,Intermolecular force ,Infrared spectroscopy ,General Chemistry ,Condensed Matter Physics ,Solvent ,Crystallography ,Solid-state nuclear magnetic resonance ,Spin diffusion ,Molecule ,General Materials Science - Abstract
Solid-state NMR (SSNMR) is capable of providing detailed structural information about organic and pharmaceutical cocrystals and complexes. SSNMR nondestructively analyzes small amounts of powdered material and generally yields data with higher information content than vibrational spectroscopy and powder X-ray diffraction methods. These advantages can be utilized in the analysis of pharmaceutical cocrystals, which are often initially produced using solvent drop grinding techniques that do not lend themselves to single crystal growth for X-ray diffraction studies. In this work, several molecular complexes and cocrystals are examined to understand the capabilities of the SSNMR techniques, particularly their ability to prove or disprove molecular association and observe structural features such as hydrogen bonding. Dipolar correlation experiments between spin pairs such as 1H−1H, 1H−13C, and 19F−13C are applied to study hydrogen bonding, intermolecular contacts, and spin diffusion to link individual molecules...
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- 2008
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19. Formation and Characterization of Crystals Containing a Pleuromutilin Derivative, Succinic Acid and Water
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Alan D. Jones, Joseph Sisko, Tran N. Pham, Matthew N. Johnson, Jeffrey Brum, Wenning Dai, Daniel B. Patience, Jacalyn S. Clawson, Royston C. P. Copley, Sonja Sharpe, and Frederick G. Vogt
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Stereochemistry ,Hydrogen bond ,General Chemistry ,Condensed Matter Physics ,chemistry.chemical_compound ,Crystallography ,chemistry ,Heteronuclear molecule ,Succinic acid ,Phase (matter) ,Molecule ,General Materials Science ,Pleuromutilin ,Derivative (chemistry) ,Powder diffraction - Abstract
An unusual pharmaceutical solid containing a pleuromutilin derivative, succinic acid and water is studied with a combination of physiochemical methods. The parent pleuromutilin derivative creates a host structure that contains large channels, which are occupied by variable amounts of both succinic acid and water. The inherent disorder of the system does not lend itself to detailed single-crystal X-ray diffraction studies; hence a combination of powder X-ray diffraction (PXRD) and solid-state NMR (SSNMR) techniques were used to characterize this system and understand its behavior. A variety of one and two-dimensional SSNMR experiments were used to understand the proton transfer and the hydrogen bonding network, including 1H−13C heteronuclear correlation experiments and measurements of the principal components of 13C chemical shift tensors. This crystal system can exist as two distinct phases; a hemisuccinate phase containing a doubly ionized succinate molecule with two cations of the pleuromutilin derivati...
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- 2008
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20. A Solid-State NMR, X-ray Diffraction, and Ab Initio Investigation into the Structures of Novel Tantalum Oxyfluoride Clusters
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Shaohui Zheng, Jochen Autschbach, François Bonhomme, Jacalyn S. Clawson, Mark A. Rodriguez, Todd M. Alam, and Steven G. Thoma
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Materials science ,General Chemical Engineering ,Ab initio ,Tantalum ,chemistry.chemical_element ,General Chemistry ,Fluorine-19 NMR ,Crystallography ,Solid-state nuclear magnetic resonance ,chemistry ,X-ray crystallography ,Materials Chemistry ,Cluster (physics) ,Magic angle spinning ,Spectroscopy - Abstract
A series of tantalum oxyfluoride materials containing the [Ta4F16O4]4− and [Ta8F24O12]8− anion clusters have been synthesized and characterized using X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (SSNMR) spectroscopy. The structure of both tantalum oxyfluoride materials display octahedrally bonded tantalum atoms with bridging oxygen and terminal fluoride atoms. The [Ta4F16O4]4− cluster is an eight-membered ring, whereas the [Ta8F24O12]8- cluster forms a cagelike structure. Solid-state dynamics of these clusters were explored by monitoring the impact of temperature on the one-dimensional (1D) 19F magic angle spinning (MAS) NMR, 13C cross-polarization (CP) MAS NMR, and two-dimensional (2D) double quantum (DQ) 19F MAS NMR spectra. The DQ 19F NMR correlation experiments allowed the through space connectivity between the different resolved fluorine environments to be determined, thus aiding in the spectral assignment and structural refinement of these materials. Ab initio 19F NMR chemical ...
- Published
- 2008
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21. A Randomized Trial of Radical Radiotherapy for the Management of pT1G3 NXM0 Transitional Cell Carcinoma of the Bladder
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K. M. Grigor, Gareth Griffiths, Roger Kockelbergh, D.M.A. Wallace, Howard Kynaston, T. Barlow, Mahesh K. B. Parmar, C. Beacock, S. J. Harland, and S. Clawson
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Male ,medicine.medical_specialty ,Urology ,medicine.medical_treatment ,Disease-Free Survival ,law.invention ,Randomized controlled trial ,law ,medicine ,Carcinoma ,Humans ,Survival rate ,Aged ,Aged, 80 and over ,Carcinoma, Transitional Cell ,Urinary bladder ,business.industry ,Carcinoma in situ ,Middle Aged ,medicine.disease ,Combined Modality Therapy ,Surgery ,Survival Rate ,Radiation therapy ,Clinical trial ,Transitional cell carcinoma ,medicine.anatomical_structure ,Urinary Bladder Neoplasms ,Disease Progression ,Female ,Neoplasm Recurrence, Local ,business - Abstract
We conducted a multicenter randomized trial in the United Kingdom to determine the efficacy of radical radiotherapy in reducing the incidence of progression of pT1G3 transitional cell carcinoma of the bladder to muscle invasive disease and subsequent disease fatality.Patients with a new diagnosis of pT1G3 NXM0 transitional cell carcinoma with unifocal disease and no carcinoma in situ (group 1), or with multifocal disease and/or carcinoma in situ (group 2) were eligible for the trial. Patients in group 1 were randomized between observation and radiotherapy to the bladder, and in group 2 between intravesical therapy and radiotherapy.From September 1991 to February 2003 a total of 210 patients from 37 centers in the United Kingdom were entered into the study. There were 77 patients in group 1 and 133 patients in group 2, and 6 patients were excluded from analysis because they were found to have pT2 disease by the reference pathologist. No evidence of an advantage with radiotherapy was found in terms of progression-free interval (hazard ratio 1.07; 95% CI 0.65, 1.74; p = 0.785), progression-free survival (hazard ratio 1.35; 95% CI 0.92, 1.98; p = 0.133) or overall survival (hazard ratio 1.32; 95% CI 0.86, 2.04; p = 0.193).To our knowledge this is the largest randomized trial performed in patients with pT1G3 disease for which 210 patients were recruited during 11 years. There is no evidence that radiotherapy is better than more conservative treatment. The prognosis of this group of patients appears to be poor irrespective of treatment and new treatment strategies need to be investigated.
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- 2007
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22. Surveillance of biting midges (Culicoides spp.) in Northern Ireland: influence of seasonality, surrounding habitat and livestock housing
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S, Jess, G M, Thompson, S, Clawson, I W N, Forsythe, I, Rea, A W, Gordon, and A K, Murchie
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Livestock ,Population Surveillance ,Epidemiological Monitoring ,Population Dynamics ,Animals ,Northern Ireland ,Seasons ,Ceratopogonidae ,Animal Distribution ,Housing, Animal ,Ecosystem - Abstract
Biting midges, Culicoides spp. (Diptera: Ceratopogonidae), are important vectors of viral pathogens. Following the outbreak of bluetongue serotype 8 in Europe between 2006 and 2009, many Culicoides surveillance programmes were initiated to identify vector-active periods, in accordance with European Commission regulation 2007/1266/EC. This study utilized surveillance data from 4 years of continuous light-trapping at 14 sites in Northern Ireland. The number of captured Culicoides varied from none during the vector-free period (December-April) to more than 36 000 per night during peak activity in the summer. The Obsoletus group represented 75% of Culicoides collected and the Pulicaris group represented 21%. A total of 91% of Culicoides were female, of which 42% were parous. Abundance data, sex ratios and parous rates suggested that both the Obsoletus and Pulicaris groups underwent three generations/year. The Obsoletus group was associated with cattle-rearing habitats and woodland, the Impunctatus group was found in habitats related to sheep rearing and the Pulicaris group were associated with both cattle and sheep. Housing did not reduce incursion of female Obsoletus group Culicoides but it did for males and for the Pulicaris group Culicoides. The influence of housing was strongly affected by time of year, probably reflecting the presence of livestock indoors/outdoors.
- Published
- 2015
23. The long-term effect of partial defoliation on the yield of short-rotation coppice willow
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S. Watson, A. C. Bell, and S. Clawson
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Willow ,biology ,business.industry ,Crop yield ,Pest control ,biology.organism_classification ,Agronomy ,Salicaceae ,Short rotation coppice ,Cultivar ,Plant breeding ,business ,Agronomy and Crop Science ,Woody plant - Abstract
Five varieties of willow were planted in a randomised block design at the Northern Ireland Horticulture and Plant Breeding Station, Loughgall, County Armagh in 1997. Three treatments were applied: control (no treatment), manual defoliation and routine control (spraying) of willow beetles. The defoliation was carried out at 75% for the first 2 years and thereafter 25% up to the first harvest in January 2001. During the second production cycle, no manual defoliation was applied in order to observe the ability of the different varieties to recover from earlier damage. The variety 78112 exhibited the highest yield loss in the first cycle as a result of defoliation (∼70%), while the vigorous variety Tora suffered least yield loss (35-43%). In the recovery phase (second production cycle 2001-2003), all the varieties showed little improvement in yields in plots that had been defoliated previously, indicating a long-term legacy of yield loss as a result of defoliation. The possible reasons for this inability to recover are discussed.
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- 2006
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24. Comparison of ABVD and Alternating or Hybrid Multidrug Regimens for the Treatment of Advanced Hodgkin's Lymphoma: Results of the United Kingdom Lymphoma Group LY09 Trial (ISRCTN97144519)
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Peter Johnson, Sally P. Stenning, Barry W. Hancock, John Radford, Matthew R. Sydes, Jan Walewski, Andrew Jack, Michael Cullen, W David J Ryder, Paul Smith, S Clawson, and Kenneth A. MacLennan
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Oncology ,Cancer Research ,Vincristine ,medicine.medical_specialty ,Chlorambucil ,business.industry ,Dacarbazine ,Hodgkin's lymphoma ,medicine.disease ,Procarbazine ,Vinblastine ,Surgery ,ABVD ,Internal medicine ,Medicine ,business ,Etoposide ,medicine.drug - Abstract
Purpose To perform an open-label, randomized, controlled trial comparing treatment with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) with two multidrug regimens (MDRs) for advanced Hodgkin's lymphoma (HL). Patients and Methods Eight hundred seven patients with advanced HL (stage III to IV, or earlier stage with systemic symptoms or bulky disease) were randomly assigned between ABVD and MDR specified before randomization as alternating chlorambucil, vinblastine, procarbazine, and prednisolone (ChlVPP) with prednisolone, doxorubicin, bleomycin, vincristine, and etoposide (PABIOE), or hybrid ChlVPP/etoposide, vincristine, and doxorubicin (EVA). Radiotherapy was planned for incomplete response or initial bulk disease. Results At 52 months median follow-up, 212 event-free survival (EFS) events (disease progression or any death) were reported. In the primary comparison, at 3 years EFS was 75% (95% CI, 71% to 79%) for ABVD and 75% (95% CI, 70% to 79%) for MDRs (hazard ratio [HR] = 1.05; 95% CI, 0.8 to 1.37; HR more than 1.0 favors ABVD). The 3-year overall survival (OS) rates were 90% (95% CI, 87% to 93%) in patients allocated ABVD and 88% (95% CI, 84% to 91%) in patients allocated MDRs (HR = 1.22; 95% CI, 0.84 to 1.77). Patients receiving MDRs experienced more grade 3/4 infection, mucositis, and neuropathy. One occurrence of myelodysplastic syndrome was reported, but no acute leukemia was reported. When the two MDRs are compared separately with ABVD, neither the alternating nor the hybrid regimen showed a statistically significant difference from ABVD for EFS or OS. Subgroup analysis suggested that MDRs may be associated with poorer outcomes in older patients (heterogeneity test of OS older or younger than 45 years, P = .020). Conclusion There was no evidence of significant difference in EFS or OS between ABVD and MDRs in the trial overall or if the two MDR versus ABVD comparisons are considered separately. ABVD remains the standard for treatment of advanced HL.
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- 2005
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25. Complete nucleotide sequences and genome organization of four chimpanzee adenoviruses
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David S. Clawson, Luk H. Vandenberghe, Steven F. Farina, Soumitra Roy, Guangping Gao, and James M. Wilson
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Chimpanzee ,Pan troglodytes ,viruses ,Molecular Sequence Data ,Sequence alignment ,Genome, Viral ,Biology ,Simian ,Genome organization ,Genome ,Open Reading Frames ,Virology ,Animals ,Amino Acid Sequence ,Phylogeny ,Genomic organization ,Genetics ,Adenovirus genome ,Adenovirus Early Proteins ,Nucleic acid sequence ,virus diseases ,biology.organism_classification ,eye diseases ,Open reading frame ,Capsid ,Adenoviruses, Simian ,Capsid Proteins ,Sequence Alignment ,Nucleotide sequence - Abstract
The complete nucleotide sequences for four adenoviruses—Simian Adenoviruses 21, 22, 23, and 24, originally isolated from chimpanzees, were determined. The genome organization of the chimpanzee adenoviruses was found to be similar to that of other adenoviruses. The viral gene products of the adenoviruses Simian Adenoviruses 22, 23, and 24 are very closely related to those of the (previously sequenced) chimpanzee adenovirus Simian Adenovirus 25. Simian Adenovirus 21 is most similar to human subgroup B adenoviruses HAdV-3, HAdV-7, and HAdV-35. Analysis of the capsid proteins hexon and fiber of the chimpanzee adenoviruses also supports the placement of Simian Adenovirus 21 in subgroup B and Simian Adenoviruses 22, 23, and 24 in subgroup E.
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- 2004
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26. 15N NMR Chemical Shift Tensors of Substituted Hexaazaisowurtzitanes: The Intermediates in the Synthesis of CL-20
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David M. Grant, Ronald J. Pugmire, Jacalyn S. Clawson, and Karen L. Anderson
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Crystallography ,Chemistry ,Chemical shift ,Intermolecular force ,Isotropy ,Organic chemistry ,Amine gas treating ,Tensor ,Physical and Theoretical Chemistry ,Solubility ,Anisotropy ,Ion - Abstract
Several cage-substituted hexaazaisowurtzitanes [2,4,6,8,10,12-hexabenzyl-2,4,6,8,10,12-hexaazaisowurtzitane (HBIW); 2,6,8,12-tetraacetyl-4,10-dibenzyl-2,4,6,8,10,12-hexaazaisowurtzitane (TADB); and 2,6,8,12-tetra-acetyl-4,10-diformyl-2,4,6,8,10,12-hexaazaisowurtzitane (TADF)] have been synthesized as intermediate steps in the synthesis of CL-20. The 1 5 N NMR isotropic and chemical shift tensor principal values have been obtained for these intermediates using CP/MAS and FIREMAT methods. Solid-state 1 5 N NMR offers unique advantages in the study of these materials, due to solubility issues and lack of high-quality X-ray crystallographic data. In addition, the caged structures possess unique electronic properties that can be useful in further refining theoretical methods. The effects of the different functional groups on the chemical shift tensor principal values of these caged amines have been evaluated and are shown to be reflected in the total anisotropy. The position of the amine within the cage is manifested in the δ 2 2 values. Nitrogen-15 NMR shielding calculations using the embedded ion method (EIM) to account for long-range intermolecular interactions show a good correlation, rmsd = 4 ppm, with the observed chemical shift tensor values.
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- 2004
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27. Ring-chain tautomerism in solid-phase erythromycin A: evidence by solid-state NMR
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David M. Grant, Robbie J. Iuliucci, Jacalyn S. Clawson, Dewy Barich, Mark S. Solum, Craig M. V. Taylor, and Jain Zhi Hu
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Nuclear and High Energy Physics ,Conformational change ,Magnetic Resonance Spectroscopy ,Radiation ,Anomer ,Stereochemistry ,Desosamine ,Resonance ,General Chemistry ,Nuclear magnetic resonance spectroscopy ,Tautomer ,Erythromycin ,chemistry.chemical_compound ,Solid-state nuclear magnetic resonance ,chemistry ,Computational chemistry ,Phase (matter) ,Instrumentation - Abstract
Chemical shift modeling, utilizing the DFT B3LYP/D95** method, provides the spectral assignment of the 35 visible 13C resonances from the solid-phase erythromycin A dihydrate. A new resonance at 110.8ppm is observed in the high-resolution 13C CP/MAS spectrum upon the application of heat or sample desiccation. With the use of the dipolar-dephasing spectral editing technique, this resonance is identified as a hemiketal carbon and the alternative hypothesis, a conformational change to the anomeric carbon of the desosamine sugar, is ruled out. Hence, the formation of a cyclic hemiketal in erythromycin A while in the solid phase is proven by solid-state NMR. The principal components of the 13C chemical-shift tensor corresponding to this hemiketal are reported. This is the first measurement of hemiketal 13C principal values. The delta11 and delta22 components are unique compared to anomeric carbon values reported in the literature.
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- 2003
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28. Determination of 13C Chemical Shift Tensors in the Presence of Hydrogen Bonding and 14N Quadrupolar Coupling: p-Aminosalicylic Acid, Isoniazid, and Pyrazinamide
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David M. Grant, Mark Strohmeier, Dewey H. Barich, Dirk Stueber, Jacalyn S. Clawson, and Ronald J. Pugmire
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Crystal ,Hydrogen bond ,Computational chemistry ,Chemistry ,Chemical shift ,Physical chemistry ,Molecule ,Crystal structure ,Tensor ,Physical and Theoretical Chemistry ,Electrostatics ,Ion - Abstract
The 1 3 C chemical-shift tensor principal values were measured for p-aminosalicylic acid, pyrazinamide, and isoniazid. A moderate-strength hydrogen bond between adjacent p-aminosalicylic acid molecules in the crystal was simulated several different ways in attempts to find a reasonable model of the electrostatic interactions in the crystal. Crystal lattice effects on the calculated chemical-shift tensors are treated by application of the embedded ion method (EIM). Coupling between 1 4 N and several 1 3 C atoms was included in the data analysis to provide more accurate 1 3 C chemical-shift tensor principal values. The chemical-shift tensors are assigned with a permutative algorithm based upon the computed chemical shifts.
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- 2002
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29. Thermal Dissociation Kinetics of Solid and Liquid Ammonium Nitrate
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Charles A. Wight, Sergey Vyazovkin, and Jacalyn S. Clawson
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General Chemical Engineering ,Ammonium nitrate ,Kinetics ,Thermodynamics ,General Chemistry ,Activation energy ,Kinetic energy ,Isothermal process ,Thermogravimetry ,chemistry.chemical_compound ,chemistry ,Vaporization ,Materials Chemistry ,Physical chemistry ,Sublimation (phase transition) - Abstract
Thermogravimetry has been used to study the kinetics of the thermal dissociation of solid and liquid ammonium nitrate. Model-fitting and model-free kinetic methods have been applied to the sets of isothermal and nonisothermal measurements to derive kinetic characteristics of the processes. The application of the model-fitting method to the isothermal data has demonstrated that both solid- and liquid-phase kinetics are characterized by a single activation energy of ∼90 kJ mol-1 and by the model of a contracting cylinder. A model-free isoconversional method has also been applied to isothermal and nonisothermal data and has yielded an activation energy of ∼90 kJ mol-1, which is essentially independent of the extent of conversion. The obtained kinetic characteristics have been assigned to the process of dissociative sublimation/vaporization.
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- 2001
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30. Molecular Marker Analysis of Leymus flavescens and Chromosome Pairing in Leymus flavescens Hybrids (Poaceae: Triticeae)
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Richard R.-C. Wang, S Clawson, Kevin B. Jensen, and David J. Hole
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Perennial plant ,biology ,Plant Science ,Leymus ,biology.organism_classification ,Rhizome ,RAPD ,chemistry.chemical_compound ,chemistry ,Molecular marker ,Botany ,Poaceae ,Triticeae ,Ecology, Evolution, Behavior and Systematics ,Hybrid - Abstract
Leymus flavescens (Scribner & Smith) Pilger, yellow wild rye, is a long‐lived, strongly rhizomatous, tetraploid (2n=4x=28) perennial grass of the tribe Triticeae distributed throughout central Washington, eastern Oregon, and the Snake River plains of Idaho. Our objectives were (1) to describe chromosome pairing and fertility in F1 hybrids between L. flavescens and North American tetraploids (2n=4x=28) L. triticoides and L. cinereus and Eurasian tetraploids L. secalinus, L. racemosus, and L. alaicus subsp. karataviensis and (2) to utilize genome‐specific random amplified polymorphic DNA (RAPD) markers to verify the genomic composition of L. flavescens. The hybrids L. flavescens × L. triticoides (NsNsXmXm), L. flavescens × L. secalinus (NsNsXmXm), L. flavescens × L. racemosus (NsNsXmXm), L. flavescens × L. cinereus (NsNsXmXm), and L. flavescens × L. alaicus subsp. karataviensis (NsNsXmXm) averaged 13.9, 13.8, 13.6, 13.1, and 11.9 bivalents per cell, respectively. Genome‐specific RAPD assay indicates that L....
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- 1999
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31. Oviposition and hatching of the clover weevil Sitona lepidus Gyll. (Coleoptera: Curculionidae)
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S. Clawson and D. J. Mowat
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biology ,Phenology ,business.industry ,Hatching ,Sitona lepidus ,Weevil ,Pest control ,Management, Monitoring, Policy and Law ,Sitona ,biology.organism_classification ,Agronomy ,Curculionidae ,Trifolium repens ,business ,Agronomy and Crop Science - Abstract
The phenology and some aspects of the biology of the clover weevil Sitona lepidus Gyll. were studied in the field and the laboratory. Oviposition and hatching were temperature dependent. Most eggs were laid in September and October, although there was also an oviposition period in early summer. Hatching was largely confined to late spring and early summer. The relevance of this to control strategies is discussed. Most eggs were laid on the plant but(were very easily dislodged and probably usually hatch on the ground. In no-choice tests, there were as many eggs laid on more cyanogenic as on less cyanogenic plants and cultivars. There was no evidence that the cyanogenic ability or any other cultivar characteristic would be useful in control strategies.
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- 1996
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32. Natural control of the Small Ermine Moth Yponomeuta padella (L.)
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S. Clawson and D.J. Mowat
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education.field_of_study ,animal structures ,Ecology ,biology ,Host (biology) ,fungi ,Population ,Zoology ,biology.organism_classification ,Population density ,Parasitoid ,Predation ,Pupa ,Botany ,Yponomeuta padella ,Yponomeuta ,Animal Science and Zoology ,education ,Agronomy and Crop Science - Abstract
The natural mortality of the Small Ermine Moth Yponomeuta padella (L.) was investigated. A previously-unknown microsporidium (Microspora), which infected the cells of the host gut wall, caused mortality in laboratory experiments. This parasite was the most probable cause of population decline in field sites and, as it readily infected the host in laboratory or field, offered the possibility of a host-specific treatment. The polyembryonic parasitoid Ageniaspis fuscicollis Dalm. (Hymenoptera) had no detectable effect on population density. Solitary hymenopteran parasitoids also had little effect, although they tended to be proportionally more numerous as the host population declined and may have contributed to the die-out of weak populations. There was no indication of significant predation, although Agria mamillata Pand. (Diptera), whose larvae preyed on the pupal aggregates, may have had a disproportionately large impact on adult emergence in relation to the number of individuals actually eaten. No significant mortality occurred during the winter, when the first instar larvae were dormant within the egg capsule.
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- 1995
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33. Quantification of HSV-1-mediated expression of the ferritin MRI reporter in the mouse brain
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David S. Clawson, William F. Goins, Eric T. Ahrens, T K Hitchens, and Bistra Iordanova
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Gene Expression Regulation, Viral ,Pathology ,medicine.medical_specialty ,Transgene ,Genetic enhancement ,Central nervous system ,Gene Expression ,Herpesvirus 1, Human ,Biology ,medicine.disease_cause ,Article ,Mice ,In vivo ,Genes, Reporter ,Gene expression ,Genetics ,medicine ,Animals ,Molecular Biology ,medicine.diagnostic_test ,Brain ,Magnetic resonance imaging ,Genetic Therapy ,Magnetic Resonance Imaging ,Ferritin ,Radiography ,medicine.anatomical_structure ,Herpes simplex virus ,Ferritins ,biology.protein ,Molecular Medicine - Abstract
The development of effective strategies for gene therapy has been hampered by difficulties verifying transgene delivery in vivo and quantifying gene expression non-invasively. Magnetic resonance imaging (MRI) offers high spatial resolution and three-dimensional views, without tissue depth limitations. The iron-storage protein ferritin is a prototype MRI gene reporter. Ferritin forms a paramagnetic ferrihydrite core that can be detected by MRI via its effect on the local magnetic field experienced by water protons. In an effort to better characterize the ferritin reporter for central nervous system applications, we expressed ferritin in the mouse brain in vivo using a neurotropic herpes simplex virus type 1 (HSV-1). We computed three-dimensional maps of MRI transverse relaxation rates in the mouse brain with ascending doses of ferritin-expressing HSV-1. We established that the transverse relaxation rates correlate significantly to the number of inoculated infectious particles. Our results are potentially useful for quantitatively assessing limitations of ferritin reporters for gene therapy applications.
- Published
- 2012
34. Construction of gene transfer vectors based on simian adenovirus 7
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Soumitra Roy, Virginie S. Adam, David S. Clawson, Angelica Medina, and James M. Wilson
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viruses ,Genetic Vectors ,Molecular Sequence Data ,medicine.disease_cause ,Virus Replication ,Cell Line ,Virology ,medicine ,Animals ,Humans ,Vector (molecular biology) ,Amino Acid Sequence ,Genomic organization ,Genetics ,biology ,Adenovirus genome ,Genetic transfer ,HEK 293 cells ,Nucleic acid sequence ,Gene Transfer Techniques ,biology.organism_classification ,eye diseases ,Adenoviridae ,Mastadenovirus ,Adenoviruses, Simian - Abstract
The complete nucleotide sequence of an isolate of simian adenovirus 7 (SAdV-7) was determined. The genome organization of this isolate was found to be similar to that of other primate adenoviruses with two principal notable points: severe truncation of the E1A and E1B 19K proteins and an E3 region encoding only the 12.5K homologue. The viral gene products of SAdV-7 are most closely related to simian adenovirus 1 (SAdV-1), and like SAdV-1, are related to the human adenovirus species HAdV-F, such as the enteric adenoviruses HAdV-40 and HAdV-41 and the recently defined HAdV-G (HAdV-52). Two kinds of gene transfer vectors were made: a replication-competent SAdV-7-based vector with no genomic deletion, and a standard replication-incompetent vector deleted for E1. Importantly, the E1-deleted vector could be propagated to high titre by trans-complementation in human HEK 293 cells.
- Published
- 2011
35. New Approaches to the Characterization of Drug Candidates by Solid-State NMR
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Frederick G. Vogt, Simon A. Watson, Jacalyn S. Clawson, Mark Strohmeier, Andrew J. Edwards, and Tran N. Pham
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Drug ,Active ingredient ,Rapid rate ,Solid-state nuclear magnetic resonance ,Polymorphism (materials science) ,Chemistry ,Stereochemistry ,media_common.quotation_subject ,Infrared spectroscopy ,Nanotechnology ,Characterization (materials science) ,media_common - Abstract
Solid-state NMR (SSNMR) spectroscopy has been found to be very useful technique for pharmaceutical development. This technique is currently applied for the study of pharmaceutical solids, ranging from detailed structural studies of active pharmaceutical ingredients (APIs) forms to analysis of complex drug products and formulations. The study suggests that solid-state structure of a pharmaceutical product can influence its properties, manufacturability, and stability. It is essential to regulate and control over solid-state structure and subsequent properties. The studies show that SSNMR is closely related to the widely used technique of solution-state NMR and possesses many of the same features. Further the study concludes that field of pharmaceutical SSNMR continues to advance at a rapid rate and will develop new molecular classes and new formulations and delivery modes in near future. Keywords: active pharmaceutical ingredients; vibrational spectroscopy; dipolar coupling; magic-angle coil spinning; polymorphism
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- 2011
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36. One-phase crystal disorder in pharmaceutical solids and its implication for solid-state stability
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Royston C. B. Copley, Jacalyn S. Clawson, Alfred Y. Lee, and Sonya Kennedy-Gabb
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Models, Molecular ,Magnetic Resonance Spectroscopy ,Chemistry, Pharmaceutical ,Pharmaceutical Science ,Crystal structure ,Crystallography, X-Ray ,Mass Spectrometry ,law.invention ,Crystal ,Drug Stability ,law ,Phase (matter) ,Technology, Pharmaceutical ,Polycyclic Compounds ,Crystallization ,Tartrates ,Molecular Structure ,Chemistry ,Amorphous solid ,Crystallography ,Solid-state nuclear magnetic resonance ,Chemical stability ,Diterpenes ,Propionates ,Powder diffraction ,Powder Diffraction - Abstract
Solid-state disorders of active pharmaceutical ingredients have been characterized by means of X-ray diffraction techniques and solid-state nuclear magnetic resonance spectroscopy. The results determined that the pleuromutilin-derivative, I, displays a unique continuous conformational disorder while retaining its long-range crystalline structure. The propionic acid (PA) version of this compound displayed partial crystalline order and site disorder of PA, depending on the quantity of PA incorporated in the structure. Thus, I is a unique example of one-phase crystalline-amorphous model. Physical and chemical stability data was acquired on these disordered systems and discussed in relation with the characterized disorder present in the crystal systems. Analysis of the results showed that in contrast to phase-separated amorphous, restrained disorders do not influence the stability.
- Published
- 2010
37. Analysis of amorphous solid dispersions using 2D solid-state NMR and (1)H T(1) relaxation measurements
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Andrew J. Edwards, Tran N. Pham, Simon A. Watson, Frederick G. Vogt, Manisha Chavda, Jacalyn S. Clawson, and Mark Strohmeier
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Ketolides ,Materials science ,Magnetic Resonance Spectroscopy ,Chemistry, Pharmaceutical ,Indomethacin ,Analytical chemistry ,Pharmaceutical Science ,Suspensions ,Drug Discovery ,Molecule ,Acetaminophen ,chemistry.chemical_classification ,Dosage Forms ,Relaxation (NMR) ,Spin–lattice relaxation ,Trehalose ,Dextrans ,Polymer ,Triazoles ,Amorphous solid ,Pyrimidines ,Solid-state nuclear magnetic resonance ,Heteronuclear molecule ,chemistry ,Solubility ,Chemical physics ,Spin diffusion ,Molecular Medicine ,Voriconazole ,Crystallization - Abstract
Solid-state NMR (SSNMR) can provide detailed structural information about amorphous solid dispersions of pharmaceutical small molecules. In this study, the ability of SSNMR experiments based on dipolar correlation, spin diffusion, and relaxation measurements to characterize the structure of solid dispersions is explored. Observation of spin diffusion effects using the 2D (1)H-(13)C cross-polarization heteronuclear correlation (CP-HETCOR) experiment is shown to be a useful probe of association between the amorphous drug and polymer that is capable of directly proving glass solution formation. Dispersions of acetaminophen and indomethacin in different polymers are examined using this approach, as well as (1)H double-quantum correlation experiments to probe additional structural features. (1)H-(19)F CP-HETCOR serves a similar role for fluorinated drug molecules such as diflunisal in dispersions, providing a rapid means to prove the formation of a glass solution. Phase separation is detected using (13)C, (19)F, and (23)Na-detected (1)H T(1) experiments in crystalline and amorphous solid dispersions that contain small domains. (1)H T(1) measurements of amorphous nanosuspensions of trehalose and dextran illustrate the ability of SSNMR to detect domain size effects in dispersions that are not glass solutions via spin diffusion effects. Two previously unreported amorphous solid dispersions involving up to three components and containing voriconazole and telithromycin are analyzed using these experiments to demonstrate the general applicability of the approach.
- Published
- 2010
38. Balancing Your Life
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James G S Clawson
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- 2009
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39. The Specter of an Oily Bear or Geopolitical Challenges of the Modern Russian Petro-State
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Gregory S. Clawson
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- 2009
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40. Powered by Feel
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James G S Clawson and Doug Newburg
- Published
- 2008
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41. Exploiting interfacial water properties for desalination and purification applications
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Zhu Chen, Tina M. Nenoff, Benjamin L. Frankamp, Gregory P. Holland, Darren R. Dunphy, Jacalyn S. Clawson, Sameer Varma, Henry Gerung, Peter J. Feibelman, Nathan W. Ockwig, George Xomeritakis, Luke L. Daemen, Frank van Swol, Ying-Bing Jiang, Christopher J. Orendorff, Darcie Farrow, Dale L. Huber, Randall T. Cygan, Joseph L. Cecchi, Hongwu Xu, Monika Hartl, Paul Stewart Crozier, C. Jeffrey Brinker, Matthew J. McGrath, Alex Travesset, Todd M. Alam, Jason D. Pless, Susan B. Rempe, Jack E. Houston, Kevin Leung, Louise J. Criscenti, Xiaoyang Zhu, J. Ilja Siepmann, Christian D. Lorenz, Seema Singh, Konrad Thuermer, Mark J. Stevens, Joshua A. Anderson, Ryan C. Major, Bruce C. Bunker, David J. Kissel, May Nyman, and Nanguo Liu
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business.industry ,Environmental engineering ,Environmental science ,Water chemistry ,Portable water purification ,Water treatment ,Bulk water ,Purification methods ,Water desalination ,Process engineering ,business ,Desalination - Abstract
A molecular-scale interpretation of interfacial processes is often downplayed in the analysis of traditional water treatment methods. However, such an approach is critical for the development of enhanced performance in traditional desalination and water treatments. Water confined between surfaces, within channels, or in pores is ubiquitous in technology and nature. Its physical and chemical properties in such environments are unpredictably different from bulk water. As a result, advances in water desalination and purification methods may be accomplished through an improved analysis of water behavior in these challenging environments using state-of-the-art microscopy, spectroscopy, experimental, and computational methods.
- Published
- 2008
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42. ChemInform Abstract: A Solid-State NMR, X-Ray Diffraction, and ab initio Investigation into the Structures of Novel Tantalum Oxyfluoride Clusters
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Jacalyn S. Clawson, François Bonhomme, Todd M. Alam, Mark A. Rodriguez, Jochen Autschbach, Shaohui Zheng, and Steven G. Thoma
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Crystallography ,Solid-state nuclear magnetic resonance ,Chemistry ,X-ray crystallography ,Ab initio ,Cluster (physics) ,Magic angle spinning ,Tantalum ,chemistry.chemical_element ,General Medicine ,Fluorine-19 NMR ,Spectroscopy - Abstract
A series of tantalum oxyfluoride materials containing the [Ta4F16O4]4− and [Ta8F24O12]8− anion clusters have been synthesized and characterized using X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (SSNMR) spectroscopy. The structure of both tantalum oxyfluoride materials display octahedrally bonded tantalum atoms with bridging oxygen and terminal fluoride atoms. The [Ta4F16O4]4− cluster is an eight-membered ring, whereas the [Ta8F24O12]8- cluster forms a cagelike structure. Solid-state dynamics of these clusters were explored by monitoring the impact of temperature on the one-dimensional (1D) 19F magic angle spinning (MAS) NMR, 13C cross-polarization (CP) MAS NMR, and two-dimensional (2D) double quantum (DQ) 19F MAS NMR spectra. The DQ 19F NMR correlation experiments allowed the through space connectivity between the different resolved fluorine environments to be determined, thus aiding in the spectral assignment and structural refinement of these materials. Ab initio 19F NMR chemical ...
- Published
- 2008
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43. Fuel traps: mapping stability via water association
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Todd M. Alam, Jeffery A. Greathouse, Susan L. Rempe, Randall T. Cygan, Kevin Leung, Marcus G. Martin, Jacalyn S. Clawson, Sameer Varma, and Dubravko Sabo
- Subjects
Hydrogen storage ,Hydrogen ,Chemical physics ,Chemistry ,Hydrogen fuel ,Hydrogen clathrate ,Clathrate hydrate ,chemistry.chemical_element ,Nanotechnology ,Energy technology ,Energy storage ,Force field (chemistry) - Abstract
Hydrogen storage is a key enabling technology required for attaining a hydrogen-based economy. Fundamental research can reveal the underlying principles controlling hydrogen uptake and release by storage materials, and also aid in characterizing and designing novel storage materials. New ideas for hydrogen storage materials come from exploiting the properties of hydrophobic hydration, which refers to water s ability to stabilize, by its mode of association, specific structures under specific conditions. Although hydrogen was always considered too small to support the formation of solid clathrate hydrate structures, exciting new experiments show that water traps hydrogen molecules at conditions of low temperatures and moderate pressures. Hydrogen release is accomplished by simple warming. While these experiments lend credibility to the idea that water could form an environmentally attractive alternative storage compound for hydrogen fuel, which would advance our nation s goals of attaining a hydrogen-based economy, much work is yet required to understand and realize the full potential of clathrate hydrates for hydrogen storage. Here we undertake theoretical studies of hydrogen in water to establish a firm foundation for predictive work on clathrate hydrate H{sub 2} storage capabilities. Using molecular simulation and statistical mechanical theories based in part on quantum mechanical descriptions of molecular interactions, we characterize the interactions between hydrogen and liquid water in terms of structural and thermodynamic properties. In the process we validate classical force field models of hydrogen in water and discover new features of hydrophobic hydration that impact problems in both energy technology and biology. Finally, we predict hydrogen occupancy in the small and large cages of hydrogen clathrate hydrates, a property unresolved by previous experimental and theoretical work.
- Published
- 2007
- Full Text
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44. Teaching Management
- Author
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James G. S. Clawson and Mark E. Haskins
- Abstract
How can every management class be a dynamic, unforgettable experience? This much-needed book distils over half a century of the authors' combined experience as university professors, consultants, and advisors to corporate training departments. In a lively, hands-on fashion, it describes the fundamental elements in every learning situation, allowing readers to adapt the suggestions to their particular teaching context. It sparks reflection on what we do in the classroom, why we do it, and how it might be done more effectively. The chapters are broadly organized according to things you do before class, things you do during class, and things you do in between and after class, so that every instructor, whether newly-minted PhDs facing their first classroom experience, experienced faculty looking to polish their teaching techniques, consultants who want to have more impact, or corporate trainers wishing to develop in-house teaching skills, can benefit from the invaluable advice given.
- Published
- 2006
- Full Text
- View/download PDF
45. Rescue of chimeric adenoviral vectors to expand the serotype repertoire
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David S. Clawson, Arbans Sandhu, James M. Wilson, James R. Miller, Oleg Lavrukhin, and Soumitra Roy
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Pan troglodytes ,Genetic Vectors ,Restriction Mapping ,Genome, Viral ,Biology ,medicine.disease_cause ,Transfection ,Virus ,Article ,Viral vector ,Cell Line ,Plasmid ,Neutralization Tests ,Virology ,medicine ,Animals ,Humans ,Vector (molecular biology) ,Serotyping ,Models, Genetic ,Repertoire ,HEK 293 cells ,Recombinant Proteins ,Adenoviridae ,DNA, Viral ,Adenovirus E1 Proteins ,Adenoviruses, Simian ,Feasibility Studies ,Adenovirus E4 Proteins ,Plasmids - Abstract
The successful use of any adenoviral vectors is predicated upon the use of a serotype that is not neutralized by circulating antibodies. However, efforts to develop a diverse repertoire of serologically distinct adenovirus vectors may be hindered by the necessity to generate cell lines to allow for the successful propagation of vectors deleted of essential genes. A strategy to construct chimeric adenoviruses whereby the rescue and propagation of an E1 deleted HAdV-B – derived adenoviral vector can be achieved using existing cell lines such as HEK 293 is reported. It is further shown that this strategy may be more widely applicable.
- Published
- 2006
46. Magnetic alignment of aqueous CTAB in nematic and hexagonal liquid crystalline phases investigated by spin-1 NMR
- Author
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Todd M. Alam, Jacalyn S. Clawson, and Gregory P. Holland
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Phase transition ,Magnetic Resonance Spectroscopy ,Biaxial nematic ,Chemistry ,Cetrimonium ,Analytical chemistry ,Hexagonal phase ,General Physics and Astronomy ,Water ,Quadrupole splitting ,Nuclear magnetic resonance spectroscopy ,Phase Transition ,Liquid Crystals ,Condensed Matter::Soft Condensed Matter ,Magnetics ,Nuclear magnetic resonance ,Electromagnetic Fields ,Models, Chemical ,Liquid crystal ,Phase (matter) ,Cetrimonium Compounds ,Anisotropy ,Computer Simulation ,Physical and Theoretical Chemistry - Abstract
Spin-1 NMR has been used to characterize the magnetically aligned nematic and hexagonal liquid crystalline phases of aqueous cetyltrimethylammonium bromide (CTAB). A nematic/hexagonal biphasic region has been identified for the first time in this system. The nematic phase is characterized by an order parameter of smaller magnitude and greater temperature dependence. Magnetic alignment kinetic rates of the two phases differ greatly, with the nematic phase showing magnetic alignment much faster than the hexagonal phase. Equilibration has been monitored over time by measuring the change in quadrupole splitting as a function of temperature. As the sample equilibrates the temperature dependence of the splitting decreases logarithmically. This work also demonstrates how the phase and order of the liquid crystal can be manipulated during the early part of equilibration.
- Published
- 2006
47. Use of chimeric adenoviral vectors to assess capsid neutralization determinants
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Di Wu, Roberto Calcedo, David S. Clawson, Corinna Lebherz, Julio Sanmiguel, Soumitra Roy, and James M. Wilson
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Adenovirus neutralization ,viruses ,Genetic Vectors ,lac operon ,In Vitro Techniques ,Antibodies, Viral ,Epitope ,Neutralization ,03 medical and health sciences ,Transduction (genetics) ,Epitopes ,Mice ,Antigen ,Neutralization Tests ,Virology ,Adenovirus ,Animals ,Fiber ,Hexon protein ,Penton ,Antigens, Viral ,030304 developmental biology ,0303 health sciences ,Mice, Inbred BALB C ,biology ,030306 microbiology ,Chimera ,Hexon ,virus diseases ,Molecular biology ,eye diseases ,3. Good health ,stomatognathic diseases ,Capsid ,Lac Operon ,biology.protein ,Adenoviruses, Simian ,Capsid Proteins ,Immunization ,Antibody - Abstract
In order to elucidate the relative importance of neutralizing determinants on each of the three major adenoviral capsid components, we have generated chimeric vectors where the hexon protein, or the fiber protein, or both hexon and fiber proteins of one serotype (Simian Adenovirus 24/Pan 7) have been replaced by those of another (Simian Adenovirus 23/Pan 6). The effect of each replacement was evaluated by neutralization assays and by attempted vector re-administration into mice. Both hexon and fiber were found to harbor neutralization epitopes although in vivo transduction was more severely affected by anti-hexon antibodies.
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- 2004
48. The Flux OS Toolkit: reusable components for OS implementation
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Jay Lepreau, B. Robinson, K. Van Maren, J. Turner, S. Clawson, and Bryan Ford
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Set (abstract data type) ,Computer science ,Operating system ,Code (cryptography) ,Reuse ,computer.software_genre ,computer ,Booting - Abstract
To an unappreciated degree, research both in operating systems (OSs) and their programming languages has been severely hampered by the lack of cleanly reusable code providing mundane low-level OS infrastructure such as bootstrap code and device drivers. The Flux OS Toolkit solves this problem by providing a set of clean, well-documented components. These components can be used as basic building blocks both for operating systems and for booting language run-time systems directly on the hardware. The toolkit's implementation itself embodies reuse techniques by incorporating components such as device drivers, file systems and networking code, unchanged, from other sources. We believe the kit also makes feasible the production of highly assured embedded and operating systems: by enabling reuse of low-level code, the high cost of detailed verification of that code can be amortized over many systems for critical environments. The OS toolkit is already heavily used in several different OS and programming language projects, and has already catalyzed research and development that would otherwise never have been attempted.
- Published
- 2002
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49. Association of anti-Yo (type I) antibody with paraneoplastic cerebellar degeneration in the setting of transitional cell carcinoma of the bladder: detection of Yo antigen in tumor tissue and fall in antibody titers following tumor removal
- Author
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J E, Greenlee, J, Dalmau, T, Lyons, S, Clawson, R H, Smith, and H R, Pirch
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DNA-Binding Proteins ,Immunoenzyme Techniques ,Carcinoma, Transitional Cell ,Urinary Bladder Neoplasms ,Cerebellar Diseases ,Paraneoplastic Syndromes ,Humans ,Female ,Nerve Tissue Proteins ,Middle Aged ,Autoantigens ,Neoplasm Proteins - Abstract
Anti-Yo (type I) autoantibodies reactive with Purkinje cell cytoplasmic antigens of 34 and 62 kd are found in the serum and cerebrospinal fluid of patients with paraneoplastic cerebellar degeneration associated with cancer of the ovary, uterus, adnexa, or breast. Anti-Yo antibody response is rarely associated with other tumors. Here, we present a patient who developed paraneoplastic cerebellar degeneration and anti-Yo antibody response in association with transitional cell carcinoma of the bladder. The presence of anti-Yo antibodies was confirmed by immunofluorescence assay and by Western blot analysis against both Purkinje cell lysates and the CDR62 fusion protein. Yo antigen was demonstrated in sections of the patient's tumor. Antibody titers fell after tumor removal. Transitional cell carcinoma should be considered in patients presenting with subacute cerebellar degeneration and anti-Yo antibody response in whom ovarian, adnexal, uterine, or breast cancer cannot be detected.
- Published
- 1999
50. Synthesis of Organo-Silane Functionalized Nanocrystal Micelles and Their Self-Assembly
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Jacalyn S. Clawson, Zhu Chen, Todd M. Alam, C. Jeffrey Brinker, and Hongyou Fan
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Models, Molecular ,Surface Properties ,Dispersity ,Inorganic chemistry ,Crystallography, X-Ray ,Biochemistry ,Micelle ,Catalysis ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Organometallic Compounds ,Microemulsion ,Particle Size ,Micelles ,Aqueous solution ,Molecular Structure ,Chemistry ,General Chemistry ,Silanes ,Silane ,Nanostructures ,Nanocrystal ,Chemical engineering ,Surface modification ,Gold ,Self-assembly ,Crystallization - Abstract
Nanocrystal (NC) synthesis and self-assembly have received much attention due to unique size-dependent properties and new collective physical properties derived from ordered NC arrays. However to fully exploit these properties, nanocrystal functionalization is critical and essential. In general, the key to functionalize NCs is maintenance of the original physical properties of the NCs, and in many situations, it is necessary to develop flexible NC surface chemistry, allowing further, subsequent functionalization. To date, most work has focused on alkane chain functionalized/ stabilized NCs prepared using hot soap 1,2 or a two-phase approach. 3 These methods can effectively make high quality NCs (narrow size distribution, preferred shape and composition, large production). Unfortunately, the alkane chains are chemically inert, preventing further chemical functionalization. In addition, these NCs are hydrophobic, precluding their direct use in bioapplications. There is an urgent need for general NC functionalization methods. Here, we report a new synthetic route to functionalize NCs with organo-silane groups through encapsulation of monodisperse, hydrophobic gold nanocrystals within the core of silane precursor micelles. Octadecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride (precursor 1) is an amphiphilic functional methoxysilane that self-assemble into micelles and liquid crystal mesophase. 4 After encapsulation, the nanocrystal micelles are monodisperse, hydrophilic, and can self-assemble into 3-D ordered arrays through silane headgroup cross-linking under acidic conditions. In comparison with the previous method concerning the preparation of hybrid silica with stabilized gold NCs, 5,6 this method is simple, general, and allows extensive further functionalization based on silane coupling chemistry. The synthesis of organo-silane functionalized gold NC micelles was based on our recently developed surfactant encapsulation techniques.7,8 In a typical nanocrystal micelle synthesis procedure, a concentrated monosized 1-dodecanethiol (DT)-stabilized gold NC chloroform solution was added to an aqueous solution of precursor 1 under vigorous stirring to create an oil-in-water microemulsion. The highly volatile chloroform was then evaporated during heating at 30 ° C( 10 min), which transfers the nanocrystals into the aqueous phase, forming NC micelles. To prevent the silane groups from extensive hydrolysis, the heating process was kept as fast as possible and the temperature was kept as low as possible (30 °C). The encapsulation was driven by the hydrophobic van der Waals interactions between the primary alkane of the stabilizing ligand and the secondary alkane of the surfactant, resulting in thermodynamically defined interdigitated “bilayer” structures (Scheme 1c), which have been used to stabilize rod- and cube-shaped nanocrystals. 9-12 The gold NC micelles are monodisperse, as suggested by UVvis spectra. Figure 1a shows the UV-vis spectra of DT-stabilized gold NCs in chloroform. The absorbance at 519 nm corresponds to the gold surface plasmon resonance band. By comparison of Figure 1a-e, we observe no difference in the positions and peak widths of the plasmon resonance band of the DT-stabilized gold NCs in chloroform, those of the corresponding water-soluble NC
- Published
- 2005
- Full Text
- View/download PDF
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