10 results on '"D. Tull"'
Search Results
2. Gate-Defined Accumulation-Mode Quantum Dots in Monolayer and Bilayer WSe2
- Author
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J. D. Tull, Jin Hu, Jeb Stacy, T. Taniguchi, A. M. Mercado, Hugh Churchill, Shiva Davari, Krishna Pandey, Kenji Watanabe, and Rabindra Basnet
- Subjects
Physics ,business.industry ,Bilayer ,General Physics and Astronomy ,02 engineering and technology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,01 natural sciences ,Quantum technology ,Coherent control ,Quantum dot ,Qubit ,0103 physical sciences ,Monolayer ,Optoelectronics ,010306 general physics ,0210 nano-technology ,business ,Quantum ,Energy (signal processing) - Abstract
Devices based on few-layer transition-metal dichalcogenides are rapidly being developed for various quantum technologies, such as valleytronic qubits and quantum emitters. Gate-defined quantum dots provide an appealing platform for coherent control of individual valley pseudospins, but well-resolved, discrete energy levels are required. The authors report gate-defined quantum dots in monolayer and bilayer WSe${}_{2}$, small enough to allow observation of transport through discrete levels. These devices thus satisfy an essential requirement for the development of (opto)electronic qubits based on valley-pseudospin states.
- Published
- 2020
3. Bazedoxifene – a promising brain active SERM that crosses the blood brain barrier and enhances spatial memory
- Author
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Jayashri Kulkarni, Andrew S. Gibbons, Anna Schroeder, D. Tull, Suresh Sundram, K. Kouremenos, Rachel Anne Hill, Xin Du, and A. Maggi
- Subjects
Selective Estrogen Receptor Modulators ,Indoles ,Endocrinology, Diabetes and Metabolism ,Hippocampus ,Estrogen receptor ,Pharmacology ,Blood–brain barrier ,Estrogen Receptor Antagonists ,Bazedoxifene ,Mice ,03 medical and health sciences ,Cognition ,0302 clinical medicine ,Endocrinology ,In vivo ,medicine ,Animals ,Biological Psychiatry ,Spatial Memory ,Hormone response element ,Estradiol ,Endocrine and Autonomic Systems ,business.industry ,Brain ,Estrogens ,030227 psychiatry ,Mice, Inbred C57BL ,Psychiatry and Mental health ,medicine.anatomical_structure ,Blood-Brain Barrier ,Selective estrogen receptor modulator ,Female ,business ,hormones, hormone substitutes, and hormone antagonists ,030217 neurology & neurosurgery ,medicine.drug - Abstract
Over 20 years of accumulated evidence has shown that the major female sex hormone 17β-estradiol can enhance cognitive functioning. However, the utility of estradiol as a therapeutic cognitive enhancer is hindered by its unwanted peripheral effects (carcinogenic). Selective estrogen receptor modulators (SERMs) avoid the unwanted effects of estradiol by acting as estrogen receptor antagonists in some tissues such as breast and uterus, but as agonists in others such as bone, and are currently used for the treatment of osteoporosis. However, understanding of their actions in the brain are limited. The third generation SERM bazedoxifene has recently been FDA approved for clinical use with an improved biosafety profile. However, whether bazedoxifene can enter the brain and enhance cognition is unknown. Using mice, the current study aimed to explore if bazedoxifene can 1) cross the blood-brain barrier, 2) rescue ovariectomy-induced hippocampal-dependent spatial memory deficit, and 3) activate neural estrogen response element (ERE)-dependent gene transcription. Using liquid chromatography-mass spectrometry (LC-MS), we firstly demonstrate that a peripheral injection of bazedoxifene can enter the brain. Secondly, we show that an acute intraperitoneal injection of bazedoxifene can rescue ovariectomy-induced spatial memory deficits. And finally, using the ERE-luciferase reporter mouse, we show in vivo that bazedoxifene can activate the ERE in the brain. The evidence shown here suggest bazedoxifene could be a viable cognitive enhancer with promising clinical applicability.
- Published
- 2020
4. Comparative Metabolomics of Mycoplasma bovis and Mycoplasma gallisepticum Reveals Fundamental Differences in Active Metabolic Pathways and Suggests Novel Gene Annotations
- Author
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Y. Masukagami, D. P. De Souza, S. Dayalan, C. Bowen, S. O’Callaghan, K. Kouremenos, B. Nijagal, D. Tull, K. A. Tivendale, P. F. Markham, M. J. McConville, G. F. Browning, F. M. Sansom, and Pieter C. Dorrestein
- Subjects
0301 basic medicine ,Mycoplasma gallisepticum ,Physiology ,In silico ,030106 microbiology ,lcsh:QR1-502 ,medicine.disease_cause ,Bioinformatics ,Biochemistry ,Microbiology ,Genome ,lcsh:Microbiology ,03 medical and health sciences ,Metabolomics ,Genetics ,medicine ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,biology ,Pathogenic bacteria ,Genome project ,Mycoplasma ,biology.organism_classification ,Computer Science Applications ,Metabolic pathway ,030104 developmental biology ,Modeling and Simulation - Abstract
Mycoplasmas are simple, but successful parasites that have the smallest genome of any free-living cell and are thought to have a highly streamlined cellular metabolism. Here, we have undertaken a detailed metabolomic analysis of two species, Mycoplasma bovis and Mycoplasma gallisepticum, which cause economically important diseases in cattle and poultry, respectively. Untargeted gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry analyses of mycoplasma metabolite extracts revealed significant differences in the steady-state levels of many metabolites in central carbon metabolism, while 13C stable isotope labeling studies revealed marked differences in carbon source utilization. These data were mapped onto in silico metabolic networks predicted from genome wide annotations. The analyses elucidated distinct differences, including a clear difference in glucose utilization, with a marked decrease in glucose uptake and glycolysis in M. bovis compared to M. gallisepticum, which may reflect differing host nutrient availabilities. The 13C-labeling patterns also revealed several functional metabolic pathways that were previously unannotated in these species, allowing us to assign putative enzyme functions to the products of a number of genes of unknown function, especially in M. bovis. This study demonstrates the considerable potential of metabolomic analyses to assist in characterizing significant differences in the metabolism of different bacterial species and in improving genome annotation. IMPORTANCE Mycoplasmas are pathogenic bacteria that cause serious chronic infections in production animals, resulting in considerable losses worldwide, as well as causing disease in humans. These bacteria have extremely reduced genomes and are thought to have limited metabolic flexibility, even though they are highly successful persistent parasites in a diverse number of species. The extent to which different Mycoplasma species are capable of catabolizing host carbon sources and nutrients, or synthesizing essential metabolites, remains poorly defined. We have used advanced metabolomic techniques to identify metabolic pathways that are active in two species of Mycoplasma that infect distinct hosts (poultry and cattle). We show that these species exhibit marked differences in metabolite steady-state levels and carbon source utilization. This information has been used to functionally characterize previously unknown genes in the genomes of these pathogens. These species-specific differences are likely to reflect important differences in host nutrient levels and pathogenic mechanisms.
- Published
- 2017
5. Comparative Metabolomics of
- Author
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Y, Masukagami, D P, De Souza, S, Dayalan, C, Bowen, S, O'Callaghan, K, Kouremenos, B, Nijagal, D, Tull, K A, Tivendale, P F, Markham, M J, McConville, G F, Browning, and F M, Sansom
- Subjects
Molecular Biology and Physiology ,carbon metabolism ,genome annotation ,mycoplasma ,metabolomics ,Research Article - Abstract
Mycoplasmas are pathogenic bacteria that cause serious chronic infections in production animals, resulting in considerable losses worldwide, as well as causing disease in humans. These bacteria have extremely reduced genomes and are thought to have limited metabolic flexibility, even though they are highly successful persistent parasites in a diverse number of species. The extent to which different Mycoplasma species are capable of catabolizing host carbon sources and nutrients, or synthesizing essential metabolites, remains poorly defined. We have used advanced metabolomic techniques to identify metabolic pathways that are active in two species of Mycoplasma that infect distinct hosts (poultry and cattle). We show that these species exhibit marked differences in metabolite steady-state levels and carbon source utilization. This information has been used to functionally characterize previously unknown genes in the genomes of these pathogens. These species-specific differences are likely to reflect important differences in host nutrient levels and pathogenic mechanisms., Mycoplasmas are simple, but successful parasites that have the smallest genome of any free-living cell and are thought to have a highly streamlined cellular metabolism. Here, we have undertaken a detailed metabolomic analysis of two species, Mycoplasma bovis and Mycoplasma gallisepticum, which cause economically important diseases in cattle and poultry, respectively. Untargeted gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry analyses of mycoplasma metabolite extracts revealed significant differences in the steady-state levels of many metabolites in central carbon metabolism, while 13C stable isotope labeling studies revealed marked differences in carbon source utilization. These data were mapped onto in silico metabolic networks predicted from genome wide annotations. The analyses elucidated distinct differences, including a clear difference in glucose utilization, with a marked decrease in glucose uptake and glycolysis in M. bovis compared to M. gallisepticum, which may reflect differing host nutrient availabilities. The 13C-labeling patterns also revealed several functional metabolic pathways that were previously unannotated in these species, allowing us to assign putative enzyme functions to the products of a number of genes of unknown function, especially in M. bovis. This study demonstrates the considerable potential of metabolomic analyses to assist in characterizing significant differences in the metabolism of different bacterial species and in improving genome annotation. IMPORTANCE Mycoplasmas are pathogenic bacteria that cause serious chronic infections in production animals, resulting in considerable losses worldwide, as well as causing disease in humans. These bacteria have extremely reduced genomes and are thought to have limited metabolic flexibility, even though they are highly successful persistent parasites in a diverse number of species. The extent to which different Mycoplasma species are capable of catabolizing host carbon sources and nutrients, or synthesizing essential metabolites, remains poorly defined. We have used advanced metabolomic techniques to identify metabolic pathways that are active in two species of Mycoplasma that infect distinct hosts (poultry and cattle). We show that these species exhibit marked differences in metabolite steady-state levels and carbon source utilization. This information has been used to functionally characterize previously unknown genes in the genomes of these pathogens. These species-specific differences are likely to reflect important differences in host nutrient levels and pathogenic mechanisms.
- Published
- 2017
6. Quality and Productivity in Injection Mold Tool Construction: A View From Manufacturing
- Author
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Bernie D. Tull
- Subjects
Engineering ,business.industry ,media_common.quotation_subject ,General Engineering ,Business system planning ,Product (business) ,Return on investment ,New product development ,Quality (business) ,Electronics ,Marketing ,business ,Productivity ,Business communication ,media_common - Abstract
In today's consumer electronics market, being first to the marketplace is paramount to success. The need for early entry into the market has its origin in the rapid evolution of the electronics industry. The saying “It's obsolete by the time you get it home” suggests the desire that drives consumers back to the marketplace for the products with the latest features. Early entry into the market can mean the difference between financial success or failure of any electronic customer premises product. It is generally recognized that the first six months in the life cycle of a low-end consumer product can represent 50 percent of the product's opportunity for return on investment. The Shreveport plant's tooling efforts extend throughout AT&T. Tooling is provided for the Consumer Products, General Business Systems, Business Communications Systems, and Network Products business units. These divisions are all involved with customer premises terminals that have product life cycles of one to four years.
- Published
- 1992
7. Comments on the use of equilibrium partitioning to establish sediment quality criteria for nonionic chemicals
- Author
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Stephen P. Truchon, James D. Tull, Nancy L. Bonnevie, Patrick J. Sheehan, Steven L. Huntley, Timothy J. Iannuzzi, and Richard J. Wenning
- Subjects
Health, Toxicology and Mutagenesis ,media_common.quotation_subject ,Environmental chemistry ,Environmental engineering ,Environmental Chemistry ,Environmental science ,Sediment ,Quality (business) ,media_common - Published
- 1995
8. Specificity modulation of barley alpha-amylase through biased random mutagenesis involving a conserved tripeptide in beta --alpha loop 7 of the catalytic (beta/alpha)(8)-barrel domain
- Author
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T E, Gottschalk, D, Tull, N, Aghajari, R, Haser, and B, Svensson
- Subjects
Models, Molecular ,Sequence Homology, Amino Acid ,Protein Conformation ,Molecular Sequence Data ,Hordeum ,Saccharomyces cerevisiae ,Ligands ,Polymerase Chain Reaction ,Protein Structure, Secondary ,Protein Structure, Tertiary ,Kinetics ,Mutagenesis ,Catalytic Domain ,Mutation ,Amino Acid Sequence ,alpha-Amylases ,Peptides ,Conserved Sequence ,Plasmids ,Protein Binding - Abstract
The relative specificity and bond cleavage pattern of barley alpha-amylase 1 (AMY1) were dramatically changed by mutation in F(286)VD that connected beta-strand 7 of the catalytic (beta/alpha)(8)-barrel to a succeeding 3(10)-helix. This conserved tripeptide of the otherwise variable beta --alpha segment 7 lacked direct ligand contact, but the nearby residues His290 and Asp291 participated in transition-state stabilization and catalysis. On the basis of sequences of glycoside hydrolase family 13, a biased random mutagenesis protocol was designed which encoded 174 putative F(286)VD variants of C95A-AMY1, chosen as the parent enzyme to avoid inactivating glutathionylation by the yeast host. The FVG, FGG, YVD, LLD, and FLE mutants showed 12-380 and 1.8-33% catalytic efficiency (k(cat)/K(m)) toward 2-chloro-4-nitrophenyl beta-D-maltoheptaoside and amylose DP17, respectively, and 0.5-50% activity for insoluble starch compared to that of C95A-AMY1. K(m) and k(cat) were decreased 2-9- and 1.3-83-fold, respectively, for the soluble substrates. The starch:oligosaccharide and amylose:oligosaccharide specificity ratios were 13-172 and 2.4-14 for mutants and 520 and 27 for C95A-AMY1, respectively. The FVG mutant released 4-nitrophenyl alpha-D-maltotrioside (PNPG(3)) from PNPG(5), whereas C95A-AMY1 produced PNPG and PNPG(2). The mutation thus favored interaction with the substrate aglycon part, while products from PNPG(6) reflected the fact that the mutation restored binding at subsite -6 which was lost in C95A-AMY1. The outcome of this combined irrational and rational protein engineering approach was evaluated considering structural accommodation of mutant side chains. FVG and FGG, present in the most active variants, represented novel sequences. This emphasized the worth of random mutagenesis and launched flexibility as a goal for beta --alpha loop 7 engineering in family 13.
- Published
- 2001
9. Potential pollution prevention and waste minimization for Department of Energy operations
- Author
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S. Pemberton, D. Tull, M. Kennicott, J. Griffin, and C. Ischay
- Subjects
Engineering ,Risk analysis (engineering) ,Waste management ,business.industry ,Hazardous waste ,Pollution prevention ,Radioactive waste ,Cleaner production ,Minification ,business ,Limited resources - Abstract
With the tightening of budgets and limited resources, it is important to ensure operations are carried out in a cost-effective and productive manner. Implementing an effective Pollution Prevention strategy can help to reduce the costs of waste management and prevent harmful releases to the environment. This document provides an estimate of the Department of Energy`s waste reduction potential from the implementation of Pollution Prevention opportunities. A team of Waste Minimization and Pollution Prevention professionals was formed to collect the data and make the estimates. The report includes a list of specific reduction opportunities for various waste generating operations and waste types. A generic set of recommendations to achieve these reduction opportunities is also provided as well as a general discussion of the approach and assumptions made for each waste generating operation.
- Published
- 1995
10. Structural implication of two saccharide conformations in the active site of a β-glycosidase
- Author
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David R. Rose, Stephen G. Withers, A. White, D. Tull, and K.L. Johns
- Subjects
biology ,Structural Biology ,Chemistry ,Stereochemistry ,biology.protein ,Active site ,Glycoside hydrolase - Published
- 1996
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