Ring-Shaped Microlanes and Chemical Barriers as a Platform for Probing Single-Cell Migration.

PubMed

Schreiber, Christoph; Segerer, Felix J; Wagner, Ernst; Roidl, Andreas; Rädler, Joachim O

2016-05-31

Quantification and discrimination of pharmaceutical and disease-related effects on cell migration requires detailed characterization of single-cell motility. In this context, micropatterned substrates that constrain cells within defined geometries facilitate quantitative readout of locomotion. Here, we study quasi-one-dimensional cell migration in ring-shaped microlanes. We observe bimodal behavior in form of alternating states of directional migration (run state) and reorientation (rest state). Both states show exponential lifetime distributions with characteristic persistence times, which, together with the cell velocity in the run state, provide a set of parameters that succinctly describe cell motion. By introducing PEGylated barriers of different widths into the lane, we extend this description by quantifying the effects of abrupt changes in substrate chemistry on migrating cells. The transit probability decreases exponentially as a function of barrier width, thus specifying a characteristic penetration depth of the leading lamellipodia. Applying this fingerprint-like characterization of cell motion, we compare different cell lines, and demonstrate that the cancer drug candidate salinomycin affects transit probability and resting time, but not run time or run velocity. Hence, the presented assay allows to assess multiple migration-related parameters, permits detailed characterization of cell motility, and has potential applications in cell biology and advanced drug screening.

High quality single shot ultrafast MeV electron diffraction from a photocathode radio-frequency gun

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Feichao; Liu, Shengguang; Zhu, Pengfei

2014-08-15

A compact ultrafast electron diffractometer, consisting of an s-band 1.6 cell photocathode radio-frequency gun, a multi-function changeable sample chamber, and a sensitive relativistic electron detector, was built at Shanghai Jiao Tong University. High-quality single-shot transmission electron diffraction patterns have been recorded by scattering 2.5 MeV electrons off single crystalline gold and polycrystalline aluminum samples. The high quality diffraction pattern indicates an excellent spatial resolution, with the ratio of the diffraction ring radius over the ring rms width beyond 10. The electron pulse width is estimated to be about 300 fs. The high temporal and spatial resolution may open new opportunities inmore » various areas of sciences.« less

High quality single shot ultrafast MeV electron diffraction from a photocathode radio-frequency gun.

PubMed

Fu, Feichao; Liu, Shengguang; Zhu, Pengfei; Xiang, Dao; Zhang, Jie; Cao, Jianming

2014-08-01

A compact ultrafast electron diffractometer, consisting of an s-band 1.6 cell photocathode radio-frequency gun, a multi-function changeable sample chamber, and a sensitive relativistic electron detector, was built at Shanghai Jiao Tong University. High-quality single-shot transmission electron diffraction patterns have been recorded by scattering 2.5 MeV electrons off single crystalline gold and polycrystalline aluminum samples. The high quality diffraction pattern indicates an excellent spatial resolution, with the ratio of the diffraction ring radius over the ring rms width beyond 10. The electron pulse width is estimated to be about 300 fs. The high temporal and spatial resolution may open new opportunities in various areas of sciences.

Distinct Temporal-Spatial Roles for Rho Kinase and Myosin Light Chain Kinase in Epithelial Purse-String Wound Closure

PubMed Central

RUSSO, JOHN M.; FLORIAN, PETER; SHEN, LE; GRAHAM, W. VALLEN; TRETIAKOVA, MARIA S.; GITTER, ALFRED H.; MRSNY, RANDALL J.; TURNER, JERROLD R.

2005-01-01

Background & Aims Small epithelial wounds heal by purse-string contraction of an actomyosin ring that is regulated by myosin light chain (MLC) kinase (MLCK) and rho kinase (ROCK). These studies aimed to define the roles of these kinases in purse-string wound closure. Methods Oligocellular and single-cell wounds were created in intestinal epithelial monolayers. Fluorescence imaging and electrophysiologic data were collected during wound closure. Human biopsies were studied immunohistochemically. Results Live-cell imaging of enhanced green fluorescent protein-β-actin defined rapid actin ring assembly within 2 minutes after wounding. This progressed to a circumferential ring within 8 minutes that subsequently contracted and closed the wound. We therefore divided this process into 2 phases: ring assembly and wound contraction. Activated rho and ROCK localized to the wound edge during ring assembly. Consistent with a primary role in the assembly phase, ROCK inhibition prevented actin ring assembly and wound closure. ROCK inhibition after ring assembly was complete had no effect. Recruitment and activation of MLCK occurred after ring assembly was complete and coincided with ring contraction. MLCK inhibition slowed and then stopped contraction but did not prevent ring assembly. MLCK inhibition also delayed barrier function recovery. Studies of human colonic biopsy specimens suggest that purse-string wound closure also occurs in vivo, because MLC phosphorylation was enhanced surrounding oligocellular wounds. Conclusions These results suggest complementary roles for these kinases in purse-string closure of experimental and in vivo oligocellular epithelial wounds; rho and ROCK are critical for actin ring assembly, while the activity of MLCK drives contraction. PMID:15825080

Bacillus subtilis MreB paralogues have different filament architectures and lead to shape remodelling of a heterologous cell system.

PubMed

Soufo, Hervé Joël Defeu; Graumann, Peter L

2010-12-01

Like many bacteria, Bacillus subtilis cells contain three actin-like MreB proteins. We show that the three paralogues, MreB, Mbl and MreBH, have different filament architectures in a heterologous cell system, and form straight filaments, helices or ring structures, different from the regular helical arrangement in B. subtilis cells. However, when coexpressed, they colocalize into a single filamentous helical structure, showing that the paralogues influence each other's filament architecture. Ring-like MreBH structures can be converted into MreB-like helical filaments by a single point mutation affecting subunit contacts, showing that MreB paralogues feature flexible filament arrangements. Time-lapse and FRAP experiments show that filaments can extend as well as shrink at both ends, and also show internal rearrangement, suggesting that filaments consist of overlapping bundles of shorter filaments that continuously turn over. Upon induction in Escherichia coli cells, B. subtilis MreB (BsMreB) filaments push the cells into strikingly altered cell morphology, showing that MreB filaments can change cell shape. E. coli cells with a weakened cell wall were ruptured upon induction of BsMreB filaments, suggesting that the bacterial actin orthologue may exert force against the cell membrane and envelope, and thus possibly plays an additional mechanical role in bacteria. © 2010 Blackwell Publishing Ltd.

A New Membrane Protein Sbg1 Links the Contractile Ring Apparatus and Septum Synthesis Machinery in Fission Yeast

PubMed Central

Sethi, Kriti; Palani, Saravanan; Cortés, Juan C. G.; Sato, Mamiko; Sevugan, Mayalagu; Ramos, Mariona; Vijaykumar, Shruthi; Osumi, Masako; Naqvi, Naweed I.; Ribas, Juan Carlos; Balasubramanian, Mohan

2016-01-01

Cytokinesis in many organisms requires a plasma membrane anchored actomyosin ring, whose contraction facilitates cell division. In yeast and fungi, actomyosin ring constriction is also coordinated with division septum assembly. How the actomyosin ring interacts with the plasma membrane and the plasma membrane-localized septum synthesizing machinery remains poorly understood. In Schizosaccharomyces pombe, an attractive model organism to study cytokinesis, the β-1,3-glucan synthase Cps1p / Bgs1p, an integral membrane protein, localizes to the plasma membrane overlying the actomyosin ring and is required for primary septum synthesis. Through a high-dosage suppressor screen we identified an essential gene, sbg1+ (suppressor of beta glucan synthase 1), which suppressed the colony formation defect of Bgs1-defective cps1-191 mutant at higher temperatures. Sbg1p, an integral membrane protein, localizes to the cell ends and to the division site. Sbg1p and Bgs1p physically interact and are dependent on each other to localize to the division site. Loss of Sbg1p results in an unstable actomyosin ring that unravels and slides, leading to an inability to deposit a single contiguous division septum and an important reduction of the β-1,3-glucan proportion in the cell wall, coincident with that observed in the cps1-191 mutant. Sbg1p shows genetic and / or physical interaction with Rga7p, Imp2p, Cdc15p, and Pxl1p, proteins known to be required for actomyosin ring integrity and efficient septum synthesis. This study establishes Sbg1p as a key member of a group of proteins that link the plasma membrane, the actomyosin ring, and the division septum assembly machinery in fission yeast. PMID:27749909

A New Membrane Protein Sbg1 Links the Contractile Ring Apparatus and Septum Synthesis Machinery in Fission Yeast.

PubMed

Sethi, Kriti; Palani, Saravanan; Cortés, Juan C G; Sato, Mamiko; Sevugan, Mayalagu; Ramos, Mariona; Vijaykumar, Shruthi; Osumi, Masako; Naqvi, Naweed I; Ribas, Juan Carlos; Balasubramanian, Mohan

2016-10-01

Cytokinesis in many organisms requires a plasma membrane anchored actomyosin ring, whose contraction facilitates cell division. In yeast and fungi, actomyosin ring constriction is also coordinated with division septum assembly. How the actomyosin ring interacts with the plasma membrane and the plasma membrane-localized septum synthesizing machinery remains poorly understood. In Schizosaccharomyces pombe, an attractive model organism to study cytokinesis, the β-1,3-glucan synthase Cps1p / Bgs1p, an integral membrane protein, localizes to the plasma membrane overlying the actomyosin ring and is required for primary septum synthesis. Through a high-dosage suppressor screen we identified an essential gene, sbg1+ (suppressor of beta glucan synthase 1), which suppressed the colony formation defect of Bgs1-defective cps1-191 mutant at higher temperatures. Sbg1p, an integral membrane protein, localizes to the cell ends and to the division site. Sbg1p and Bgs1p physically interact and are dependent on each other to localize to the division site. Loss of Sbg1p results in an unstable actomyosin ring that unravels and slides, leading to an inability to deposit a single contiguous division septum and an important reduction of the β-1,3-glucan proportion in the cell wall, coincident with that observed in the cps1-191 mutant. Sbg1p shows genetic and / or physical interaction with Rga7p, Imp2p, Cdc15p, and Pxl1p, proteins known to be required for actomyosin ring integrity and efficient septum synthesis. This study establishes Sbg1p as a key member of a group of proteins that link the plasma membrane, the actomyosin ring, and the division septum assembly machinery in fission yeast.

Hsp90 interaction with Cdc2 and Plo1 kinases contributes to actomyosin ring condensation in fission yeast.

PubMed

Santino, Andrea; Tallada, Victor A; Jimenez, Juan; Garzón, Andrés

2012-08-01

In Schizosaccharomyces pombe, cytokinesis occurs by ordered recruitment of actomyosin components at the division site, followed by lateral condensation to produce a ring-like structure early in anaphase, which eventually matures and contracts at the end of mitosis. We found that in temperature-sensitive hsp90-w1 mutant cells, encoding an Hsp90 mutant protein, ring components were recruited to form a cortical network at the division site, but this network failed to condense into a compact ring, suggesting a role for Hsp90 in this particular step. hsp90-w1 mutant shows strong genetic interaction with specific mutant alleles of the fission yeast cdc2, such as cdc2-33. Interestingly, actomyosin ring defects in hsp90-w1 cdc2-33 mutant cells resembled that of hsp90-w1 single mutant at restrictive temperature. Noteworthy, similar genetic interaction was found with a mutant allele of polo-like kinase, plo1-ts4, suggesting that Hsp90 collaborates with Cdc2 and Plo1 cell cycle kinases to condense medial ring components. In vitro analyses suggested that Cdc2 and Plo1 physically interact with Hsp90. Association of Cdc2 to Hsp90 was ATP independent, while Plo1 binds to this chaperone in an ATP-dependent manner, indicating that these two kinases interact with different Hsp90 complexes. Overall, our analyses of hsp90-w1 reveal a possible role for this chaperone in medial ring condensation in association with Cdc2 and Plo1 kinases.

Contractile Ring-independent Localization of DdINCENP, a Protein Important for Spindle Stability and CytokinesisD⃞V⃞

PubMed Central

Chen, Qian; Li, Hui; De Lozanne, Arturo

2006-01-01

Dictyostelium DdINCENP is a chromosomal passenger protein associated with centromeres, the spindle midzone, and poles during mitosis and the cleavage furrow during cytokinesis. Disruption of the single DdINCENP gene revealed important roles for this protein in mitosis and cytokinesis. DdINCENP null cells lack a robust spindle midzone and are hypersensitive to microtubule-depolymerizing drugs, suggesting that their spindles may not be stable. Furthermore DdCP224, a protein homologous to the microtubule-stabilizing protein TOGp/XMAP215, was absent from the spindle midzone of DdINCENP null cells. Overexpression of DdCP224 rescued the weak spindle midzone defect of DdINCENP null cells. Although not required for the localization of the myosin II contractile ring and subsequent formation of a cleavage furrow, DdINCENP is important for the abscission of daughter cells at the end of cytokinesis. Finally, we show that the localization of DdINCENP at the cleavage furrow is modulated by myosin II but it occurs by a mechanism different from that controlling the formation of the contractile ring. PMID:16339076

Method of upgrading oils containing hydroxyaromatic hydrocarbon compounds to highly aromatic gasoline

DOEpatents

Baker, Eddie G.; Elliott, Douglas C.

1993-01-01

The present invention is a multi-stepped method of converting an oil which is produced by various biomass and coal conversion processes and contains primarily single and multiple ring hydroxyaromatic hydrocarbon compounds to highly aromatic gasoline. The single and multiple ring hydroxyaromatic hydrocarbon compounds in a raw oil material are first deoxygenated to produce a deoxygenated oil material containing single and multiple ring aromatic compounds. Then, water is removed from the deoxygenated oil material. The next step is distillation to remove the single ring aromatic compouns as gasoline. In the third step, the multiple ring aromatics remaining in the deoxygenated oil material are cracked in the presence of hydrogen to produce a cracked oil material containing single ring aromatic compounds. Finally, the cracked oil material is then distilled to remove the single ring aromatics as gasoline.

Method of upgrading oils containing hydroxyaromatic hydrocarbon compounds to highly aromatic gasoline

DOEpatents

Baker, E.G.; Elliott, D.C.

1993-01-19

The present invention is a multi-stepped method of converting an oil which is produced by various biomass and coal conversion processes and contains primarily single and multiple ring hydroxyaromatic hydrocarbon compounds to highly aromatic gasoline. The single and multiple ring hydroxyaromatic hydrocarbon compounds in a raw oil material are first deoxygenated to produce a deoxygenated oil material containing single and multiple ring aromatic compounds. Then, water is removed from the deoxygenated oil material. The next step is distillation to remove the single ring aromatic compounds as gasoline. In the third step, the multiple ring aromatics remaining in the deoxygenated oil material are cracked in the presence of hydrogen to produce a cracked oil material containing single ring aromatic compounds. Finally, the cracked oil material is then distilled to remove the single ring aromatics as gasoline.

Assembly of flammutoxin, a cytolytic protein from the edible mushroom Flammulina velutipes, into a pore-forming ring-shaped oligomer on the target cell.

PubMed

Tomita, T; Ishikawa, D; Noguchi, T; Katayama, E; Hashimoto, Y

1998-07-01

Flammutoxin has been previously isolated as a cardiotoxic and cytolytic polypeptide of 22 or 32 kDa from the fruiting bodies of the edible mushroom Flammulina velutipes. In the present study, we purified flammutoxin as a single haemolytic protein of 31 kDa and studied the mode of its cytolytic action. (1) Flammutoxin caused efflux of potassium ions from human erythrocytes and swelling of the cells before haemolysis. (2) Flammutoxin did not lyse human erythrocytes in the presence of non-electrolytes with hydrodynamic diameters of >5.0 nm, although it caused leakage of potassium ions and swelling of the cells under the same conditions. (3) Experiments including solubilization of cell-bound toxin with 2% (w/v) SDS at 20 degrees C and subsequent Western immunoblots showed that flammutoxin formed a band corresponding to 180 kDa under the conditions where it lysed erythrocytes. (4) Electron microscopy of flammutoxin-treated human erythrocytes revealed the presence of a ring-shaped structure with outer and inner diameters of 10 and 5 nm, respectively, on the cells. (5) A ring-shaped toxin oligomer of the same dimensions was solubilized from the toxin-treated human erythrocytes with 2% (w/v) SDS at 20 degrees C and isolated by a sucrose-gradient ultracentrifugation. These data indicated that flammutoxin assembles into a ring-shaped oligomer possessing a hydrophilic pore of 4-5 nm on target cells.

Cartilage canals in the distal intermediate ridge of the tibia of fetuses and foals are surrounded by different types of collagen.

PubMed

Hellings, Ingunn Risnes; Dolvik, Nils Ivar; Ekman, Stina; Olstad, Kristin

2017-10-01

Some epiphyseal growth cartilage canals are surrounded by a ring of hypereosinophilic matrix consisting of collagen type I. Absence of the collagen type I ring may predispose canal vessels to failure and osteochondrosis, which can lead to fragments in joints (osteochondrosis dissecans). It is not known whether the ring develops in response to programming or biomechanical force. The distribution that may reveal the function of the ring has only been described in the distal femur of a limited number of foals. It is also not known which cells are responsible for producing the collagen ring. The aims of the current study were to examine fetuses and foals to infer whether the ring forms in response to biomechanical force or programming, to describe distribution and to investigate which cell type produces the ring. The material consisted of 46 fetuses and foals from 293 days of gestation to 142 days old, of both sexes and different breeds, divided into three groups, designated the naïve group up to and including the day of birth, the adapting group from 2 days up to and including 14 days old, and the loaded group from 15 days and older. The distal tibia was sawn into parasagittal slabs and the cranial half of the central slab from the intermediate ridge was examined by light microscopy and immunohistochemical staining for collagen type I. Presence, completeness and location of the collagen ring was compared, as was the quantity of perivascular mesenchymal cells. An eosinophilic ring present on HE-stained sections was seen in every single fetus and foal examined, which corresponded to collagen type I in immunostained sections. A higher proportion of cartilage canals were surrounded by an eosinophilic ring in the naïve and adapting groups at 73 and 76%, respectively, compared with the loaded group at 51%. When considering only patent canals, the proportion of canals with an eosinophilic ring was higher in the adapting and loaded than the naïve group of foals. The ring was present around 90 and 81% of patent canals in the deep and middle layers, respectively, compared with 58% in the superficial layer, and the ring was more often complete around deep compared with superficial canals. The ring was absent or partial around chondrifying canals. When an eosinophilic ring was present around patent canals, it was more common for the canal to contain one or more layers of perivascular mesenchymal cells rather than few to no layers. It was also more common for the collagen ring to be more complete around canals that contained many as opposed to few mesenchymal cells. In conclusion, the proportion of cartilage canals that had an eosinophilic ring was similar in all three groups of fetuses and foals, indicating that the presence of the collagen ring was mostly programmed, although some adaptation was evident. The ring was more often present around deep, compared with superficial canals, indicating a role in preparation for ossification. The collagen ring appeared to be produced by perivascular mesenchymal cells. © 2017 The Authors. Journal of Anatomy published by John Wiley & Sons Ltd on behalf of Anatomical Society.

Investigation of sliding DNA clamp dynamics by single-molecule fluorescence, mass spectrometry and structure-based modeling

PubMed Central

Gadkari, Varun V; Harvey, Sophie R; Raper, Austin T; Chu, Wen-Ting; Wang, Jin; Wysocki, Vicki H; Suo, Zucai

2018-01-01

Abstract Proliferating cell nuclear antigen (PCNA) is a trimeric ring-shaped clamp protein that encircles DNA and interacts with many proteins involved in DNA replication and repair. Despite extensive structural work to characterize the monomeric, dimeric, and trimeric forms of PCNA alone and in complex with interacting proteins, no structure of PCNA in a ring-open conformation has been published. Here, we use a multidisciplinary approach, including single-molecule Förster resonance energy transfer (smFRET), native ion mobility-mass spectrometry (IM-MS), and structure-based computational modeling, to explore the conformational dynamics of a model PCNA from Sulfolobus solfataricus (Sso), an archaeon. We found that Sso PCNA samples ring-open and ring-closed conformations even in the absence of its clamp loader complex, replication factor C, and transition to the ring-open conformation is modulated by the ionic strength of the solution. The IM-MS results corroborate the smFRET findings suggesting that PCNA dynamics are maintained in the gas phase and further establishing IM-MS as a reliable strategy to investigate macromolecular motions. Our molecular dynamic simulations agree with the experimental data and reveal that ring-open PCNA often adopts an out-of-plane left-hand geometry. Collectively, these results implore future studies to define the roles of PCNA dynamics in DNA loading and other PCNA-mediated interactions. PMID:29529283

Signet ring cell melanocytic nevus: report of a case over trichilemmal cyst and review of the literature.

PubMed

Sabater Marco, Vicente; Escutia Muñoz, Begoña; Morera Faet, Arturo; Botella Estrada, Rafael

2012-02-01

Different melanocytic nevi have been reported as being associated with dermal cysts. Signet ring cell melanocytic nevus is a rare variant of melanocytic nevus characterized by cells with signet ring morphology within a common melanocytic nevus. This article describes an exceptional case of melanocytic nevus composed exclusively of signet ring cells over a trichilemmal cyst. Histologically, above the cyst, there was a small, symmetrical and sharply demarcated lesion showing a compound proliferation of small, round, monomorphous cells with signet ring morphology. Immunohistochemically, signet ring cells were negative for cytokeratin AE1/3, leukocyte common antigen, HMB-45, and CD34. Occasionally, isolated signet ring cells were positive for S-100 and melan A. Melanocytic nevus composed of signet ring cells should raise the differential diagnosis with other cutaneous tumors exhibiting signet ring cells. Previous cases of this entity reported in the literature are also reviewed.

The relevance and implications of signet-ring cell adenocarcinoma of the oesophagus.

PubMed

Bleaney, Christopher William; Barrow, Mickhaiel; Hayes, Stephen; Ang, Yeng

2018-03-01

To review the current understanding of signet-ring type oesophageal adenocarcinoma including evidence for prognosis. We conducted a literature search of nine healthcare literature databases for articles detailing the biology and clinical outcomes of signet-ring cell adenocarcinoma of the oesophagus. The impact of signet-ring cell morphology was analysed and detailed in written text and tabular format. Current understanding of the biology of signet-ring cell adenocarcinoma of the oesophagus was summarised. Signet-ring cell carcinoma was represented in 7.61% of the 18 989 cases of oesophageal carcinoma reviewed in multiple studies. The presence of signet-ring cells conferred a worse prognosis and these tumours responded differently to conventional treatments as compared with typical adenocarcinoma. Little is known about the biological features of signet-ring cell adenocarcinoma of the oesophagus. Work in gastric lesions has identified potential targets for future treatments such as CDH1 and RHOA genes. Categorisation of signet-ring cell carcinomas by the proportion of signet-ring cells within tumours differs among clinicians despite WHO criteria for classification. The current UK guidelines for histopathological reporting of oesophageal tumours do not emphasise the importance of identifying signet-ring cells. The presence of signet-ring cells in oesophageal adenocarcinomas leads to poorer clinical outcomes. Current understanding of signet-ring cell biology in oesophageal cancer is limited. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Myosin concentration underlies cell size–dependent scalability of actomyosin ring constriction

PubMed Central

Wright, Graham D.; Leong, Fong Yew; Chiam, Keng-Hwee; Chen, Yinxiao; Jedd, Gregory; Balasubramanian, Mohan K.

2011-01-01

In eukaryotes, cytokinesis is accomplished by an actomyosin-based contractile ring. Although in Caenorhabditis elegans embryos larger cells divide at a faster rate than smaller cells, it remains unknown whether a similar mode of scalability operates in other cells. We investigated cytokinesis in the filamentous fungus Neurospora crassa, which exhibits a wide range of hyphal circumferences. We found that N. crassa cells divide using an actomyosin ring and larger rings constricted faster than smaller rings. However, unlike in C. elegans, the total amount of myosin remained constant throughout constriction, and there was a size-dependent increase in the starting concentration of myosin in the ring. We predict that the increased number of ring-associated myosin motors in larger rings leads to the increased constriction rate. Accordingly, reduction or inhibition of ring-associated myosin slows down the rate of constriction. Because the mechanical characteristics of contractile rings are conserved, we predict that these findings will be relevant to actomyosin ring constriction in other cell types. PMID:22123864

Localization of FtsZ in Helicobacter pylori and Consequences for Cell Division

PubMed Central

Specht, Mara; Dempwolff, Felix; Schätzle, Sarah; Thomann, Ralf

2013-01-01

Of the various kinds of cell division, the most common mode is binary fission, the division of a cell into two morphologically identical daughter cells. However, in the case of asymmetric cell division, Caulobacter crescentus produces two morphologically and functionally distinct cell types. Here, we have studied cell cycle progression of the human pathogen Helicobacter pylori using a functional green fluorescent protein (GFP) fusion of FtsZ protein and membrane staining. In small cells, representing newly divided cells, FtsZ localizes to a single cell pole. During the cell cycle, spiral intermediates are formed until an FtsZ ring is positioned with very little precision, such that central as well as acentral rings can be observed. Daughter cells showed considerably different sizes, suggesting that H. pylori divides asymmetrically. Fluorescence recovery after photobleaching (FRAP) analyses demonstrate that the H. pylori FtsZ ring is about as dynamic as that of Escherichia coli but that polar assemblies show less turnover. Strikingly, our results demonstrate that H. pylori cell division follows a different route from that in E. coli and Bacillus subtilis. It is also different from that in C. crescentus, where cytokinesis regulation proteins like MipZ play a role. Therefore, this report provides the first cell-biological analysis of FtsZ dynamics in the human pathogen H. pylori and even in epsilonproteobacteria to our knowledge. In addition, analysis of the filament architecture of H. pylori and E. coli FtsZ filaments in the heterologous system of Drosophila melanogaster S2 Schneider cells revealed that both have different filamentation properties in vivo, suggesting a unique intrinsic characteristic of each protein. PMID:23335414

MinD directly interacting with FtsZ at the H10 helix suggests a model for robust activation of MinC to destabilize FtsZ polymers.

PubMed

Taviti, Ashoka Chary; Beuria, Tushar Kant

2017-09-07

Cell division in bacteria is a highly controlled and regulated process. FtsZ, a bacterial cytoskeletal protein, forms a ring-like structure known as the Z-ring and recruits more than a dozen other cell division proteins. The Min system oscillates between the poles and inhibits the Z-ring formation at the poles by perturbing FtsZ assembly. This leads to an increase in the FtsZ concentration at the mid-cell and helps in Z-ring positioning. MinC, the effector protein, interferes with Z-ring formation through two different mechanisms mediated by its two domains with the help of MinD. However, the mechanism by which MinD triggers MinC activity is not yet known. We showed that MinD directly interacts with FtsZ with an affinity stronger than the reported MinC-FtsZ interaction. We determined the MinD-binding site of FtsZ using computational, mutational and biochemical analyses. Our study showed that MinD binds to the H10 helix of FtsZ. Single-point mutations at the charged residues in the H10 helix resulted in a decrease in the FtsZ affinity towards MinD. Based on our findings, we propose a novel model for MinCD-FtsZ interaction, where MinD through its direct interaction with FtsZ would trigger MinC activity to inhibit FtsZ functions. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Synthesis of conformationally North-locked pyrimidine nucleosides built on an oxabicyclo[3.1.0]hexane scaffold.

PubMed

Ludek, Olaf R; Marquez, Victor E

2012-01-20

Beginning with a known 3-oxabicyclo[3.1.0]hexane scaffold (I), the relocation of the fused cyclopropane ring bond and the shifting of the oxygen atom to an alternative location engendered a new 2-oxabicyclo[3.1.0]hexane template (II) that mimics more closely the tetrahydrofuran ring of conventional nucleosides. The synthesis of this new class of locked nucleosides involved a novel approach that required the isocyanate II (B = NCO) with a hydroxyl-protected scaffold as a pivotal intermediate that was obtained in 11 steps from a known dihydrofuran precursor. The completion of the nucleobases was successfully achieved by quenching the isocyanate with the lithium salts of the corresponding acrylic amides that led to the uracil and thymidine precursors in a single step. Ring closure of these intermediates led to the target, locked nucleosides. The anti-HIV activity of 29 (uridine analogue), 31 (thymidine analogue), and 34 (cytidine analogue) was explored in human osteosarcoma (HOS) cells or modified HOS cells (HOS-313) expressing the herpes simplex virus 1 thymidine kinase (HSV-1 TK). Only the cytidine analogue showed moderate activity in HOS-313 cells, which means that the compounds are not good substrates for the cellular kinases.

Regulation of Innate Immune Responses by Bovine Herpesvirus 1 and Infected Cell Protein 0 (bICP0)

PubMed Central

Jones, Clinton

2009-01-01

Bovine herpesvirus 1 (BoHV-1) infected cell protein 0 (bICP0) is an important transcriptional regulatory protein that stimulates productive infection. In transient transfection assays, bICP0 also inhibits interferon dependent transcription. bICP0 can induce degradation of interferon stimulatory factor 3 (IRF3), a cellular transcription factor that is crucial for activating beta interferon (IFN-β) promoter activity. Recent studies also concluded that interactions between bICP0 and IRF7 inhibit trans-activation of IFN-β promoter activity. The C3HC4 zinc RING (really important new gene) finger located near the amino terminus of bICP0 is important for all known functions of bICP0. A recombinant virus that contains a single amino acid change in a well conserved cysteine residue of the C3HC4 zinc RING finger of bICP0 grows poorly in cultured cells, and does not reactivate from latency in cattle confirming that the C3HC4 zinc RING finger is crucial for viral growth and pathogenesis. A bICP0 deletion mutant does not induce plaques in permissive cells, but induces autophagy in a cell type dependent manner. In summary, the ability of bICP0 to stimulate productive infection, and repress IFN dependent transcription plays a crucial role in the BoHV-1 infection cycle. PMID:21994549

Screening and Selection of New Antagonists of the RING-Mediated Hdm2/Hdmx Interaction

DTIC Science & Technology

2012-03-01

NUMBER (include area code) Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 W81XWH-10-1-0151 Screening and Selection of New ...in which individual bacteria express a different cyclotide. This comprises a new single cell-single compound approach to identify protein-protein... functionally inhibited at multiple steps to reactivate p53 function . Numbered circles indicate potential therapeutical targets for the development of Hdm2

Structural studies on a high-pressure polymorph of NaYSi 2O 6

NASA Astrophysics Data System (ADS)

Kahlenberg, Volker; Konzett, Jürgen; Kaindl, Reinhard

2007-06-01

High-pressure synthesis experiments in the system Na 2O-Y 2O 3-SiO 2 revealed the existence of a previously unknown polymorph of NaYSi 2O 6 or Na 3Y 3[Si 3O 9] 2 which was quenched from 3.0 GPa and 1000 °C. Structural investigations on this modification have been performed using single-crystal X-ray diffraction data collected at ambient conditions. Furthermore, unpolarized micro-Raman spectra have been obtained from single-crystal material. The high-P modification of NaYSi 2O 6 crystallizes in the centrosymmetric space group C2/ c with 12 formula units per cell ( a=8.2131(9) Å, b=10.3983(14) Å, c=17.6542(21) Å, β=100.804(9)°, V=1481.0(3) Å 3, R(| F|)=0.033 for 1142 independent observed reflections) and belongs to the group of cyclo-silicates. Basic building units are isolated three-membered [Si 3O 9] rings located in layers parallel to (010). Within a single layer the rings are concentrated in strings parallel to [100]. The sequence of directedness of up ( U) or down ( D) pointing tetrahedra of a single ring is UUU or DDD, respectively. Stacking of the layers parallel to b results in the formation of a three-dimensional structure in which yttrium and sodium cations are incorporated for charge compensation. In more detail, four non-tetrahedral cation positions can be differentiated which are coordinated by 6 and 8 oxygen ligands. Refinements of the site occupancies did not reveal any indication for mixed Na-Y populations on these positions. Finally, several geometrical parameters of rings occurring in cyclo-trisilicate structures have been compiled and are discussed.

The Arabidopsis arc5 and arc6 mutations differentially affect plastid morphology in pavement and guard cells in the leaf epidermis.

PubMed

Fujiwara, Makoto T; Yasuzawa, Mana; Kojo, Kei H; Niwa, Yasuo; Abe, Tomoko; Yoshida, Shigeo; Nakano, Takeshi; Itoh, Ryuuichi D

2018-01-01

Chloroplasts, or photosynthetic plastids, multiply by binary fission, forming a homogeneous population in plant cells. In Arabidopsis thaliana, the division apparatus (or division ring) of mesophyll chloroplasts includes an inner envelope transmembrane protein ARC6, a cytoplasmic dynamin-related protein ARC5 (DRP5B), and members of the FtsZ1 and FtsZ2 families of proteins, which co-assemble in the stromal mid-plastid division ring (FtsZ ring). FtsZ ring placement is controlled by several proteins, including a stromal factor MinE (AtMinE1). During leaf mesophyll development, ARC6 and AtMinE1 are necessary for FtsZ ring formation and thus plastid division initiation, while ARC5 is essential for a later stage of plastid division. Here, we examined plastid morphology in leaf epidermal pavement cells (PCs) and stomatal guard cells (GCs) in the arc5 and arc6 mutants using stroma-targeted fluorescent proteins. The arc5 PC plastids were generally a bit larger than those of the wild type, but most had normal shapes and were division-competent, unlike mutant mesophyll chloroplasts. The arc6 PC plastids were heterogeneous in size and shape, including the formation of giant and mini-plastids, plastids with highly developed stromules, and grape-like plastid clusters, which varied on a cell-by-cell basis. Moreover, unique plastid phenotypes for stomatal GCs were observed in both mutants. The arc5 GCs rarely lacked chlorophyll-bearing plastids (chloroplasts), while they accumulated minute chlorophyll-less plastids, whereas most GCs developed wild type-like chloroplasts. The arc6 GCs produced large chloroplasts and/or chlorophyll-less plastids, as previously observed, but unexpectedly, their chloroplasts/plastids exhibited marked morphological variations. We quantitatively analyzed plastid morphology and partitioning in paired GCs from wild-type, arc5, arc6, and atminE1 plants. Collectively, our results support the notion that ARC5 is dispensable in the process of equal division of epidermal plastids, and indicate that dysfunctions in ARC5 and ARC6 differentially affect plastid replication among mesophyll cells, PCs, and GCs within a single leaf.

Mechanical influences in bacterial morphogenesis and cell division

NASA Astrophysics Data System (ADS)

Sun, Sean

2010-03-01

Bacterial cells utilize a ring-like organelle (the Z-ring) to accomplish cell division. The Z-ring actively generates a contractile force and influences cell wall growth. We will discuss a general model of bacterial morphogenesis where mechanical forces are coupled to the growth dynamics of the cell wall. The model suggests a physical mechanism that determines the shapes of bacteria cells. The roles of several bacterial cytoskeletal proteins and the Z-ring are discussed. We will also explore molecular mechanisms of force generation by the Z-ring and how cells can generate mechanical forces without molecular motors.

A Single Nucleotide Polymorphism Uncovers a Novel Function for the Transcription Factor Ace2 during Candida albicans Hyphal Development

PubMed Central

Orellana-Muñoz, Sara; Gutiérrez-Escribano, Pilar; Arnáiz-Pita, Yolanda; Dueñas-Santero, Encarnación; Suárez, M. Belén; Bougnoux, Marie-Elisabeth; del Rey, Francisco; Sherlock, Gavin; d’Enfert, Christophe; Correa-Bordes, Jaime; de Aldana, Carlos R. Vázquez

2015-01-01

Candida albicans is a major invasive fungal pathogen in humans. An important virulence factor is its ability to switch between the yeast and hyphal forms, and these filamentous forms are important in tissue penetration and invasion. A common feature for filamentous growth is the ability to inhibit cell separation after cytokinesis, although it is poorly understood how this process is regulated developmentally. In C. albicans, the formation of filaments during hyphal growth requires changes in septin ring dynamics. In this work, we studied the functional relationship between septins and the transcription factor Ace2, which controls the expression of enzymes that catalyze septum degradation. We found that alternative translation initiation produces two Ace2 isoforms. While full-length Ace2, Ace2L, influences septin dynamics in a transcription-independent manner in hyphal cells but not in yeast cells, the use of methionine-55 as the initiation codon gives rise to Ace2S, which functions as the nuclear transcription factor required for the expression of cell separation genes. Genetic evidence indicates that Ace2L influences the incorporation of the Sep7 septin to hyphal septin rings in order to avoid inappropriate activation of cell separation during filamentous growth. Interestingly, a natural single nucleotide polymorphism (SNP) present in the C. albicans WO-1 background and other C. albicans commensal and clinical isolates generates a stop codon in the ninth codon of Ace2L that mimics the phenotype of cells lacking Ace2L. Finally, we report that Ace2L and Ace2S interact with the NDR kinase Cbk1 and that impairing activity of this kinase results in a defect in septin dynamics similar to that of hyphal cells lacking Ace2L. Together, our findings identify Ace2L and the NDR kinase Cbk1 as new elements of the signaling system that modify septin ring dynamics in hyphae to allow cell-chain formation, a feature that appears to have evolved in specific C. albicans lineages. PMID:25875512

Aim44p regulates phosphorylation of Hof1p to promote contractile ring closure during cytokinesis in budding yeast

PubMed Central

Wolken, Dana M. Alessi; McInnes, Joseph; Pon, Liza A.

2014-01-01

Whereas actomyosin and septin ring organization and function in cytokinesis are thoroughly described, little is known regarding the mechanisms by which the actomyosin ring interacts with septins and associated proteins to coordinate cell division. Here we show that the protein product of YPL158C, Aim44p, undergoes septin-dependent recruitment to the site of cell division. Aim44p colocalizes with Myo1p, the type II myosin of the contractile ring, throughout most of the cell cycle. The Aim44p ring does not contract when the actomyosin ring closes. Instead, it forms a double ring that associates with septin rings on mother and daughter cells after cell separation. Deletion of AIM44 results in defects in contractile ring closure. Aim44p coimmunoprecipitates with Hof1p, a conserved F-BAR protein that binds both septins and type II myosins and promotes contractile ring closure. Deletion of AIM44 results in a delay in Hof1p phosphorylation and altered Hof1p localization. Finally, overexpression of Dbf2p, a kinase that phosphorylates Hof1p and is required for relocalization of Hof1p from septin rings to the contractile ring and for Hof1p-triggered contractile ring closure, rescues the cytokinesis defect observed in aim44∆ cells. Our studies reveal a novel role for Aim44p in regulating contractile ring closure through effects on Hof1p. PMID:24451263

Noise reduction as affected by the extent and distribution of acoustic treatment in a turbofan engine inlet

NASA Technical Reports Server (NTRS)

Minner, G. L.; Homyak, L.

1976-01-01

An inlet noise suppressor for a TF-34 engine designed to have three acoustically treated rings was tested with several different ring arrangements. The configurations included: all three rings; two outer rings; single outer ring; single intermediate ring, and finally no rings. It was expected that as rings were removed, the acoustic performance would be degraded considerably. While a degradation occurred, it was not as large as predictions indicated. The prediction showed good agreement with the data only for the full-ring inlet configuration. The underpredictions which occurred with ring removal were believed a result of ignoring the presence of spinning modes which are known to damp more rapidly in cylindrical ducts than would be predicted by least attenuated mode or plane wave analysis.

Embedding the dynamics of a single delay system into a feed-forward ring.

PubMed

Klinshov, Vladimir; Shchapin, Dmitry; Yanchuk, Serhiy; Wolfrum, Matthias; D'Huys, Otti; Nekorkin, Vladimir

2017-10-01

We investigate the relation between the dynamics of a single oscillator with delayed self-feedback and a feed-forward ring of such oscillators, where each unit is coupled to its next neighbor in the same way as in the self-feedback case. We show that periodic solutions of the delayed oscillator give rise to families of rotating waves with different wave numbers in the corresponding ring. In particular, if for the single oscillator the periodic solution is resonant to the delay, it can be embedded into a ring with instantaneous couplings. We discover several cases where the stability of a periodic solution for the single unit can be related to the stability of the corresponding rotating wave in the ring. As a specific example, we demonstrate how the complex bifurcation scenario of simultaneously emerging multijittering solutions can be transferred from a single oscillator with delayed pulse feedback to multijittering rotating waves in a sufficiently large ring of oscillators with instantaneous pulse coupling. Finally, we present an experimental realization of this dynamical phenomenon in a system of coupled electronic circuits of FitzHugh-Nagumo type.

High power single-longitudinal-mode Ho:YLF unidirectional ring laser based on a composite structure of acousto-optic device and wave plate

NASA Astrophysics Data System (ADS)

Dai, T. Y.; Fan, Z. G.; Wu, J.; Ju, Y. L.; Yao, B. Q.; Zhang, Z. G.; Teng, K.; Xu, X. G.; Duan, X. M.

2017-05-01

We report a unidirectional single-longitudinal-mode Ho:YLF ring laser. An acousto-optic modulator and two half-wave plates were used to enforce the Ho:YLF ring laser in a unidirectional operation. The single-longitudinal-mode output power could reach 3.73 W successfully when the incident pump power was 16.4 W. The corresponding slope efficiency was 27.1%. The wavelength of the single-longitudinal-mode Ho:YLF ring laser was 2063.8 nm. The M2 factor was 1.12. The results illustrated that the single-longitudinal-mode output power could be further enhanced by increasing the radio frequency power of the acousto-optic modulator.

Detection and direction discrimination of single vortex rings by harbour seals (Phoca vitulina).

PubMed

Krüger, Yvonne; Hanke, Wolf; Miersch, Lars; Dehnhardt, Guido

2018-04-25

Harbour seals possess highly sensitive vibrissae that enable them to track hydrodynamic trails left behind by a swimming fish. Most of these trails contain vortex rings as a main hydrodynamic component. They may reveal information about their generator as the trails differ depending on the fish species, the fish's body shape, size and swimming style. In addition, fish generate single vortex rings in diverse natural situations. In this study, the ability of blindfolded stationary harbour seals to detect and analyse single vortex rings regarding directional information has been investigated. In three different behavioural experiments, the animals were trained to respond to single artificially generated vortex rings. The results show that harbour seals are able to respond to a variety of different vortex rings upon vibrissal stimulation. The investigation of the minimum hydrodynamically perceivable angle revealed that it is at least as small as 5.7 deg, which was the smallest adjustable angle. Moreover, harbour seals are capable of analysing the travel direction of a vortex ring perceived by the mystacial vibrissae irrespective of whether the vibrissae were stimulated ipsilaterally or contralaterally. In situations in which no complex hydrodynamic trail is available, it is advantageous for a hunting seal to be able to extract information from a single vortex ring. © 2018. Published by The Company of Biologists Ltd.

Scanning Laser Infrared Molecular Spectrometer (SLIMS)

NASA Technical Reports Server (NTRS)

Scott, David C.; Rickey, Kelly; Ksendzov, Alexander; George, Warren P.; Aljabri, Abdullah S.; Steinkraus, Joel M.

2012-01-01

This prototype innovation is a novel design that achieves very long, effective laser path lengths that are able to yield ppb (parts per billion) and sub-ppb measurements of trace gases. SLIMS can also accommodate multiple laser channels covering a wide range of wavelengths, resulting in detection of more chemicals of interest. The mechanical design of the mirror cell allows for the large effective path length within a small footprint. The same design provides a robust structure that lends itself to being immune to some of the alignment challenges that similar cells face. By taking a hollow cylinder and by cutting an elliptically or spherically curved surface into its inner wall, the basic geometry of a reflecting ring is created. If the curved, inner surface is diamond-turned and highly polished, a surface that is very highly reflective can be formed. The surface finish can be further improved by adding a thin chrome or gold film over the surface. This creates a high-quality, curved, mirrored surface. A laser beam, which can be injected from a small bore hole in the wall of the cylinder, will be able to make many low-loss bounces around the ring, creating a large optical path length. The reflecting ring operates on the same principle as the Herriott cell. The difference exists in the mirror that doesn't have to be optically aligned, and which has a relatively large, internal surface area that lends itself to either open air or evacuated spectroscopic measurements. This solid, spherical ring mirror removes the possibility of mirror misalignment caused by thermal expansion or vibrations, because there is only a single, solid reflecting surface. Benefits of the reflecting ring come into play when size constraints reduce the size of the system, especially for space missions in which mass is at a premium.

Growth and assembly of cobalt oxide nanoparticle rings at liquid nanodroplets with solid junction.

PubMed

Zhou, Yilong; Powers, Alexander S; Zhang, Xiaowei; Xu, Tao; Bustillo, Karen; Sun, Litao; Zheng, Haimei

2017-09-28

Using liquid cell TEM, we imaged the formation of CoO nanoparticle rings. Nanoparticles nucleated and grew tracing the perimeter of droplets sitting on the SiN x solid substrate, and finally formed necklace-like rings. By tracking single nanoparticle trajectories during the ring formation and an estimation of the forces between droplets and nanoparticles using a simplified model, we found the junction of liquid nanodroplets with a solid substrate is the attractive site for CoO nanoparticles. Coalescing droplets were capable of pushing nanoparticles to the perimeter of the new droplet and nanoparticles on top of the droplets rolled off toward the perimeter. We propose that the curved surface morphology of the droplets created a force gradient that contributed to the assembly of nanoparticles at the droplet perimeter. Revealing the dynamics of nanoparticle movements and the interactions of nanoparticles with the liquid nanodroplet provides insights on developing novel self-assembly strategies for building precisely defined nanostructures on solid substrates.

Cutaneous amelanotic signet-ring cell malignant melanoma with interspersed myofibroblastic differentiation in a young cat.

PubMed

Hirz, Manuela; Herden, Christiane

2016-07-01

The diagnosis of malignant melanoma can be difficult because these tumors can be amelanotic and may contain diverse variants and divergent differentiations, of which the signet-ring cell subtype is very rare and has only been described in humans, dogs, cats, and a hamster. We describe herein histopathologic and immunohistochemical approaches taken to diagnose a case of signet-ring cell malignant melanoma with myofibroblastic differentiation in a cat. A tumor within the abdominal skin of a 2-year-old cat was composed of signet-ring cells and irregularly interwoven streams of spindle cells. Both neoplastic cell types were periodic-acid-Schiff, Fontana, and Sudan black B negative. Signet-ring cells strongly expressed vimentin and S100 protein. Spindle cells strongly expressed vimentin and smooth muscle actin; some cells expressed S100, moderately neuron-specific enolase, and others variably actin and desmin. A few round cells expressed melan A, and a few plump spindle cells expressed melan A and PNL2, confirming the diagnosis of amelanotic signet-ring cell malignant melanoma with myofibroblastic differentiation in a cat. Differential diagnoses were excluded, including signet-ring cell forms of adenocarcinomas, lymphomas, liposarcomas, leiomyosarcomas, squamous cell carcinomas, basal cell carcinomas, and adnexal tumors. © 2016 The Author(s).

Extracellular cell wall β(1,3)glucan is required to couple septation to actomyosin ring contraction.

PubMed

Muñoz, Javier; Cortés, Juan Carlos G; Sipiczki, Matthias; Ramos, Mariona; Clemente-Ramos, José Angel; Moreno, M Belén; Martins, Ivone M; Pérez, Pilar; Ribas, Juan Carlos

2013-10-28

Cytokinesis has been extensively studied in different models, but the role of the extracellular cell wall is less understood. Here we studied this process in fission yeast. The essential protein Bgs4 synthesizes the main cell wall β(1,3)glucan. We show that Bgs4-derived β(1,3)glucan is required for correct and stable actomyosin ring positioning in the cell middle, before the start of septum formation and anchorage to the cell wall. Consequently, β(1,3)glucan loss generated ring sliding, oblique positioned rings and septa, misdirected septum synthesis indicative of relaxed rings, and uncoupling between a fast ring and membrane ingression and slow septum synthesis, suggesting that cytokinesis can progress with defective septum pushing and/or ring pulling forces. Moreover, Bgs4-derived β(1,3)glucan is essential for secondary septum formation and correct primary septum completion. Therefore, our results show that extracellular β(1,3)glucan is required for cytokinesis to connect the cell wall with the plasma membrane and for contractile ring function, as proposed for the equivalent extracellular matrix in animal cells.

Extracellular cell wall β(1,3)glucan is required to couple septation to actomyosin ring contraction

PubMed Central

Muñoz, Javier; Cortés, Juan Carlos G.; Sipiczki, Matthias; Ramos, Mariona; Clemente-Ramos, José Angel; Moreno, M. Belén; Martins, Ivone M.; Pérez, Pilar

2013-01-01

Cytokinesis has been extensively studied in different models, but the role of the extracellular cell wall is less understood. Here we studied this process in fission yeast. The essential protein Bgs4 synthesizes the main cell wall β(1,3)glucan. We show that Bgs4-derived β(1,3)glucan is required for correct and stable actomyosin ring positioning in the cell middle, before the start of septum formation and anchorage to the cell wall. Consequently, β(1,3)glucan loss generated ring sliding, oblique positioned rings and septa, misdirected septum synthesis indicative of relaxed rings, and uncoupling between a fast ring and membrane ingression and slow septum synthesis, suggesting that cytokinesis can progress with defective septum pushing and/or ring pulling forces. Moreover, Bgs4-derived β(1,3)glucan is essential for secondary septum formation and correct primary septum completion. Therefore, our results show that extracellular β(1,3)glucan is required for cytokinesis to connect the cell wall with the plasma membrane and for contractile ring function, as proposed for the equivalent extracellular matrix in animal cells. PMID:24165938

Single-ring magnetic cusp low gas pressure ion source

DOEpatents

Bacon, Frank M.; Brainard, John P.; O'Hagan, James B.; Walko, Robert J.

1985-01-01

A single-ring magnetic cusp low gas pressure ion source designed for use in a sealed, nonpumped neutron generator utilizes a cathode and an anode, three electrically floating electrodes (a reflector behind the cathode, a heat shield around the anode, and an aperture plate), together with a single ring-cusp magnetic field, to establish and energy-filtering mechanism for producing atomic-hydrogen ions.

Camphor revisited: involvement of a unique monooxygenase in metabolism of 2-oxo-delta 3-4,5,5-trimethylcyclopentenylacetic acid by Pseudomonas putida.

PubMed Central

Ougham, H J; Taylor, D G; Trudgill, P W

1983-01-01

Previously, Pseudomonas putida was shown to degrade (+)-camphor, and cleavage of the first ring of the bicyclic structure involved two monooxygenases (a hydroxylase and a ring oxygen-inserting enzyme), a dehydrogenase, and spontaneous cleavage of an unstable oxygenation product (lactone). Cleavage of the second ring was not demonstrated but was assumed also to occur by ring oxygen insertion, since the predicted oxygenation product was extracted from whole-cell incubation systems. Our investigation established that metabolism of the first ring cleavage intermediate, 2-oxo-delta 3-4,5,5-trimethylcyclopentenylacetic acid, occurred through the sequential action of two inducible enzymes, a coenzyme A ester synthetase and an oxygenase. The oxygenase was purified to homogeneity and had a molecular weight of 106,000. This enzyme carried a single molecule of flavin adenine dinucleotide and consisted of two identical subunits. Iron was not present at a significant level. The oxygenase was specific for NADPH as the electron donor and absolutely specific for the coenzyme A ester of 2-oxo-delta 3-4,5,5-trimethylcyclopentenylacetic acid as the substrate. The reaction stoichiometry was compatible with this enzyme being a monooxygenase, and a mass spectral analysis of the methyl ester of the product confirmed the insertion of a single oxygen atom. The enzyme appeared to be analogous to, although distinct from. 2,5-diketocamphane 1,2-monooxygenase in catalyzing a "biological Baeyer-Villiger" reaction with the formation of a lactone. Structural analogy suggested that this lactone, like the first, was also unstable and susceptible to spontaneous ring opening, although this was not experimentally established. Images PMID:6848481

Camphor revisited: involvement of a unique monooxygenase in metabolism of 2-oxo-delta 3-4,5,5-trimethylcyclopentenylacetic acid by Pseudomonas putida.

PubMed

Ougham, H J; Taylor, D G; Trudgill, P W

1983-01-01

Previously, Pseudomonas putida was shown to degrade (+)-camphor, and cleavage of the first ring of the bicyclic structure involved two monooxygenases (a hydroxylase and a ring oxygen-inserting enzyme), a dehydrogenase, and spontaneous cleavage of an unstable oxygenation product (lactone). Cleavage of the second ring was not demonstrated but was assumed also to occur by ring oxygen insertion, since the predicted oxygenation product was extracted from whole-cell incubation systems. Our investigation established that metabolism of the first ring cleavage intermediate, 2-oxo-delta 3-4,5,5-trimethylcyclopentenylacetic acid, occurred through the sequential action of two inducible enzymes, a coenzyme A ester synthetase and an oxygenase. The oxygenase was purified to homogeneity and had a molecular weight of 106,000. This enzyme carried a single molecule of flavin adenine dinucleotide and consisted of two identical subunits. Iron was not present at a significant level. The oxygenase was specific for NADPH as the electron donor and absolutely specific for the coenzyme A ester of 2-oxo-delta 3-4,5,5-trimethylcyclopentenylacetic acid as the substrate. The reaction stoichiometry was compatible with this enzyme being a monooxygenase, and a mass spectral analysis of the methyl ester of the product confirmed the insertion of a single oxygen atom. The enzyme appeared to be analogous to, although distinct from. 2,5-diketocamphane 1,2-monooxygenase in catalyzing a "biological Baeyer-Villiger" reaction with the formation of a lactone. Structural analogy suggested that this lactone, like the first, was also unstable and susceptible to spontaneous ring opening, although this was not experimentally established.

Circularly split-ring-resonator-based frequency-reconfigurable antenna

NASA Astrophysics Data System (ADS)

Rahman, M. A.; Faruque, M. R. I.; Islam, M. T.

2017-01-01

In this paper, an antenna with frequency configurability in light of a circularly split-ring resonator (CSRR) is introduced. The proposed reconfigurable monopole antenna consists of a microstrip-fed hook-shaped structure and a CSRR having single reconfigurable split only. A new band of radiation unlike the band radiated from monopole only is observed due to magnetic coupling between the CSRR and the monopole antenna. The resonance frequency of the CSRR can be arbitrarily chosen by varying the dimension and relative position of its gap with the monopole, which leads the antenna to become reconfigurable one. By using a single switch with perfect electric conductor at the gap of CSRR cell, the effect of CSRR can be deactivated and, hence, it is possible to suppress the corresponding resonance, resulting in a frequency-reconfigurable antenna. Commercially available Computer Simulation Technology microwave studio based on finite integration technique was adopted throughout the study.

Magnetic moment of single layer graphene rings

NASA Astrophysics Data System (ADS)

Margulis, V. A.; Karpunin, V. V.; Mironova, K. I.

2018-01-01

Magnetic moment of single layer graphene rings is investigated. An analytical expression for the magnetic moment as a function of the magnetic field flux through the one-dimensional quantum rings is obtained. This expression has the oscillation character. The oscillation period is equal to one flux quanta.

The contractile ring coordinates curvature-dependent septum assembly during fission yeast cytokinesis

PubMed Central

Zhou, Zhou; Munteanu, Emilia Laura; He, Jun; Ursell, Tristan; Bathe, Mark; Huang, Kerwyn Casey; Chang, Fred

2015-01-01

The functions of the actin-myosin–based contractile ring in cytokinesis remain to be elucidated. Recent findings show that in the fission yeast Schizosaccharomyces pombe, cleavage furrow ingression is driven by polymerization of cell wall fibers outside the plasma membrane, not by the contractile ring. Here we show that one function of the ring is to spatially coordinate septum cell wall assembly. We develop an improved method for live-cell imaging of the division apparatus by orienting the rod-shaped cells vertically using microfabricated wells. We observe that the septum hole and ring are circular and centered in wild-type cells and that in the absence of a functional ring, the septum continues to ingress but in a disorganized and asymmetric manner. By manipulating the cleavage furrow into different shapes, we show that the ring promotes local septum growth in a curvature-dependent manner, allowing even a misshapen septum to grow into a more regular shape. This curvature-dependent growth suggests a model in which contractile forces of the ring shape the septum cell wall by stimulating the cell wall machinery in a mechanosensitive manner. Mechanical regulation of the cell wall assembly may have general relevance to the morphogenesis of walled cells. PMID:25355954

Synthesis of Conformationally North-Locked Pyrimidine Nucleosides Built on an Oxa-bicyclo[3.1.0]hexane Scaffold

PubMed Central

Ludek, Olaf R.; Marquez, Victor E.

2011-01-01

Beginning with a known 3-oxabicyclo[3.1.0]hexane scaffold (I), the relocation of the fused cyclopropane ring bond and the shifting of the oxygen atom to an alternative location engendered a new 2-oxabicyclo[3.1.0]hexane template (II) that mimics more closely the tetrahydrofuran ring of conventional nucleosides. The synthesis of this new class of locked nucleosides involved a novel approach that required the isocyanate II (B = NCO) with a hydroxyl-protected scaffold as a pivotal intermediate that was obtained in eleven steps from a known dihydrofuran precursor. The completion of the nucleobases was successfully achieved by quenching the isocyanate with the lithium salts of the corresponding acrylic amides that led to the uracil and thymidine precursors in a single step. Ring closure of these intermediates led to the target, locked nucleosides. The anti-HIV activity of 29 (uridine analogue), 31 (thymidine analogue), and 34 (cytidine analogue) was explored in human osteosarcoma (HOS) cells or modified HOS cells (HOS-313) expressing the herpes simplex virus 1 thymidine kinase (HSV-1 TK). Only the cytidine analogue showed moderate activity in HOS-313 cells, which means that the compounds are not good substrates for the cellular kinases. PMID:22026578

Primary signet ring cell adenocarcinoma of the uterine cervix - A rare neoplasm that raises the question of metastasis to the cervix.

PubMed

Cracchiolo, Bernadette; Kuhn, Theresa; Heller, Debra

2016-04-01

Primary signet ring cell adenocarcinoma is extremely rare. Signet ring cell carcinoma is more commonly primary in the stomach or breast, and the more likely metastatic disease to the cervix needs to be ruled out. We present a case of primary signet ring cell carcinoma of the cervix and review the literature.

The ring of life hypothesis for eukaryote origins is supported by multiple kinds of data

PubMed Central

McInerney, James; Pisani, Davide; O'Connell, Mary J.

2015-01-01

The literature is replete with manuscripts describing the origin of eukaryotic cells. Most of the models for eukaryogenesis are either autogenous (sometimes called slow-drip), or symbiogenic (sometimes called big-bang). In this article, we use large and diverse suites of ‘Omics' and other data to make the inference that autogeneous hypotheses are a very poor fit to the data and the origin of eukaryotic cells occurred in a single symbiosis. PMID:26323755

ARPA Semiannual Technical Report, Materials Science

DTIC Science & Technology

1973-12-15

determine the oscillator output properties. A newly designed cylindrical-ring-electrode Pockel’s cell is used for single picosecond pulse...satellite pulse trains and pulse noise. A contacted dye cell has been constructed and tested for this new system. Considerable experience in its ur-e...by the definition - - - -- ■’ -’ ’" - - ■ - - ■; - . v -• . . . -. 1.,-. •. • .’■-."■ ’,■■ . • ’*■ ," ’".** "."’" ", ■," ■T^r,T^" nT1

Single-ring ablation compared with standard circumferential pulmonary vein isolation using remote magnetic catheter navigation.

PubMed

Sohns, Christian; Bergau, Leonard; Seegers, Joachim; Lüthje, Lars; Vollmann, Dirk; Zabel, Markus

2014-10-01

In ablation of atrial fibrillation, the single-ring method aims for isolation of the posterior wall of the left atrium (LA) including the pulmonary veins (PVs) but avoiding posterior LA lesions. The aim of this randomized prospective study was to evaluate safety and efficacy of remote magnetic navigation (RMN)-guided single-ring ablation strategy as compared to standard RMN-guided circumferential PV ablation (PVA). Eighty consecutive patients undergoing PVA were enrolled prospectively and randomized equally into two study groups. RMN using the Stereotaxis system and open-irrigated 3.5-mm ablation catheters were used with a 3D mapping system in all procedures. Forty patients underwent RMN-guided single-ring ablation, and 40 patients received RMN-guided circumferential PVA. In the circumferential group, 3.3 ± 1.1 PVs were successfully isolated at the end of the procedure as compared to 3.1 ± 1.3 in the single-ring (box) group (p=0.38). All patients in the box group required additional posterior lesions in order to achieve electrical isolation of the PVs. Single-ring ablation was associated with longer procedure duration (p=0.01) and ablation time (p=0.001). After a single procedure, the proportion of patients free of any atrial tachycardia (AT)/atrial fibrillation (AF) episode at 12-month follow-up was 57 % in the box group and 58 % in the circ group. Using RMN, only minor complications have been observed. RMN-guided single-ring PVA provides comparable acute and long-term success rates as compared to RMN-guided circumferential PVA but requires additional posterior lesions to achieve PV isolation and increased procedure and ablation time. Procedural complication rates are low when using RMN.

Determination of ion mobility in EHD flow zone of plasma generator

NASA Astrophysics Data System (ADS)

Sumariyah, Kusminarto, Hermanto, Arief; Nuswantoro, Pekik

2015-12-01

Determination has been carried out for ion mobility in EHD flow zone generated using a pin-concentric multiple ring electrodes and a pin-single ring electrode used as a comparator. The pin needle was made from stainless steel with a tip diameter of 0.18 mm. The concentris multiple ring electrode in form three/two concentric ring electrodes which made of metal material connected to each other. Each ring of three concentric ring electrode has a diameter of 24 mm, 16 mm and 8 mm. And each ring of two concentric ring electrode has a diameter of 24 mm and 16 mm. Single ring electrode has a diameter24 mm. The all ring has same of width and thickness were 2 mm and 3 mm. EHD was generated by using a DC high voltage of 10 kV. Pin functional as an active electrode of corona discharge while the all ring electrodes acted as ions collector and passive electrodes. The experimental results show that the ion current is proportional to V2 according to calculations by Chouelo for hyperbolic-field approach. Ion mobility obtained from the quadratic polynomial fitting of experimental data were current and voltage as well as Choelo formulation. The results showed that the mobility of ions in the EHD flow zones utilizing pin-consentric multiple ring electrode larger than utilizing pin-single ring electrode. Pin-three Consentic ring electrode has the largest of ion mobility

Mechanism of Cytokinetic Contractile Ring Constriction in Fission Yeast

PubMed Central

Stachowiak, Matthew R.; Laplante, Caroline; Chin, Harvey F.; Guirao, Boris; Karatekin, Erdem; Pollard, Thomas D.; O’Shaughnessy, Ben

2014-01-01

SUMMARY Cytokinesis involves constriction of a contractile actomyosin ring. The mechanisms generating ring tension and setting the constriction rate remain unknown, since the organization of the ring is poorly characterized, its tension was rarely measured, and constriction is coupled to other processes. To isolate ring mechanisms we studied fission yeast protoplasts, where constriction occurs without the cell wall. Exploiting the absence of cell wall and actin cortex, we measured ring tension and imaged ring organization, which was dynamic and disordered. Computer simulations based on the amounts and biochemical properties of the key proteins showed that they spontaneously self-organize into a tension-generating bundle. Together with rapid component turnover, the self-organization mechanism continuously reassembles and remodels the constricting ring. Ring constriction depended on cell shape, revealing that the ring operates close to conditions of isometric tension. Thus, the fission yeast ring sets its own tension, but other processes set the constriction rate. PMID:24914559

Study of EHD flow generator's efficiencies utilizing pin to single ring and multi-concentric rings electrodes

NASA Astrophysics Data System (ADS)

Sumariyah; Kusminart; Hermanto, A.; Nuswantoro, P.

2016-11-01

EHD flow or ionic wind yield corona discharge is a stream coming from the ionized gas. EHD is generated by a strong electric field and its direction follows the electric field lines. In this study, the efficiency of the EHD flow generators utilizing pin-multi concentric rings electrodes (P-MRE) and the EHD pin-single ring electrode (P-SRE) have been measured. The comparison of efficiencies two types of the generator has been done. EHD flow was generated by using a high-voltage DC 0-10 KV on the electrode pin with a positive polarity and electrode ring/ multi-concentric rings of negative polarity. The efficiency was calculated by comparison between the mechanical power of flow to the electrical power that consumed. We obtained that the maximum efficiency of EHD flow generator utilizing pin-multi concentric rings electrodes was 0.54% and the maximum efficiency of EHD flow generator utilizing a pin-single ring electrode was 0.23%. Efficiency of EHD with P-MRE 2.34 times Efficiency of EHD with P-SRE

Mechanical seal having a single-piece, perforated mating ring

DOEpatents

Khonsari, Michael M [Baton Rouge, LA; Somanchi, Anoop K [Fremont, CA

2007-08-07

A mechanical seal (e.g., single mechanical seals, double mechanical seals, tandem mechanical seals, bellows, pusher mechanical seals, and all types of rotating and reciprocating machines) with reduced contact surface temperature, reduced contact surface wear, or increased life span. The mechanical seal comprises a rotating ring and a single-piece, perforated mating ring, which improves heat transfer by controllably channeling coolant flow through the single-piece mating ring such that the coolant is in substantially uniform thermal contact with a substantial portion of the interior surface area of the seal face, while maintaining the structural integrity of the mechanical seal and minimizing the potential for coolant flow interruptions to the seal face caused by debris or contaminants (e.g., small solids and trash) in the coolant.

[A comparative study of three types of IUD].

PubMed

Lai, K R; Chen, Q B

1991-11-01

In Zhejiang Province, China, there are 2.7 million IUD users. 90% of them use stainless steel single ring. In order to evaluate the effectiveness of the IUDs, the Provincial Family Planning Commission organized a prospective comparative study on 3 kinds of IUDs: the single ring made in Wuxi, the metal ring with plastic core made in Beijing, and the copper TCU 220c made in Tianjin. Between October 1985 and March 1986 1199 healthy women aged 20-39 who had 2 or fewer normal deliveries and without previous history of ectopic pregnancy were screened and recruited to the study. They were randomly assigned to be inserted with the IUDs. 400 women had single ring, 402 women had metal with plastic core, and 397 had TCu 220c. 8 postinsertion follow-up visits were conducted up to 3 years, and menstruations were recorded every month. During the study, 4 cases were lost to follow-up. In the single-ring group, the cumulative continuation rates at 12, 24, and 36 months were 73.4, 66.7, and 65.7% respectively. For the metal-plastic ring group, it was 80.9, 72.3, and 69.3% and for the TCu 220c group, it was 94.5, 88.4, and 83.1%, respectively. The expulsion rates among the 3 kinds of IUDs were statistically significant at 12, 24, and 36 months. The highest expulsion rates were the single ring and TCu 220c were the lowest. The pregnancy rates were highest among metal-plastic ring users and lowest among TCu 220c users. The differences were not statistically significant between single ring and metal-plastic ring users. Discontinuation due to excessive menstrual bleeding were similar among the 3 methods probably due to treatment of the users who experienced excessive bleeding. Younger women and women who experienced fewer pregnancies were found to have higher expulsion and pregnancy rates. But the occurrence of side effects such as prolonged menstrual periods, spotting, and back pain were highest among TCu 220c users. It was recommended that the more effective TCu 220c should be promoted to replace the single ring. Since different sizes of TCu IUDs have been developed, it would be possible to reduce excessive menstrual bleeding and its side effects.

Spin flip in single quantum ring with Rashba spin–orbit interation

NASA Astrophysics Data System (ADS)

Liu, Duan-Yang; Xia, Jian-Bai

2018-03-01

We theoretically investigate spin transport in the elliptical ring and the circular ring with Rashba spin–orbit interaction. It is shown that when Rashba spin–orbit interaction is relatively weak, a single circular ring can not realize spin flip, however an elliptical ring may work as a spin-inverter at this time, and the influence of the defect of the geometry is not obvious. Howerver if a giant Rashba spin–orbit interaction strength has been obtained, a circular ring can work as a spin-inverter with a high stability. Project supported by the National Natural Science Foundation of China (Grant No. 11504016).

Single-Stage Resection of Type II Constriction Rings in Limbs on the Basis of Histologic and Magnetic Resonance Imaging Observations: A Retrospective Study of 21 Consecutive Patients.

PubMed

Jiang, Yongkang; Mao, Hailei; Yang, Xi; Zhou, Shengbo; Ni, Feng; Xu, Qiming; Wang, Bin

2016-07-01

The purpose of this study was to determine the feasibility of single-stage resection for type II congenital constriction rings by means of histologic examination of resected specimens and imaging examination of affected extremities, and to evaluate the appearance and function of the extremities after single-stage surgery. The features of the skin on the constriction rings and the subcutaneous tissues were identified through continuous sectioning, hematoxylin and eosin staining, and immunohistologic staining of specimens of type II constriction rings obtained by means of surgery. The relationship between the constriction rings and the deep main blood vessels was evaluated using magnetic resonance imaging. Single-stage resection of the constriction band, reduction of the fascial flap, and triangular flap-plasty were performed for 21 patients. The appearance, lymphedema, and movement of the extremities were compared before and after the operation. Type II constriction rings in the extremities had normal full-layer skin structures. Collagen was found deposited densely at the base of the grooves, but the normal subcutaneous tissue space remained, and the vital nerves and blood vessels were unaffected. Complete resection of the constriction rings was achieved in all 21 patients, and lymphedema subsided 2 months after the operation. No episode of recurrence was found, and limb function was not affected at 26-month follow-up. Type II congenital constriction rings in limbs possess normal subcutaneous tissue spaces. A single-stage operation, which includes complete resection of the rings, fascial flap reduction, and triangular flap-plasty, could achieve a satisfactory appearance and good function. Therapeutic, III.

Pure moment testing for spinal biomechanics applications: Fixed versus sliding ring cable-driven test designs.

PubMed

Eguizabal, Johnny; Tufaga, Michael; Scheer, Justin K; Ames, Christopher; Lotz, Jeffrey C; Buckley, Jenni M

2010-05-07

In vitro multi-axial bending testing using pure moment loading conditions has become the standard in evaluating the effects of different types of surgical intervention on spinal kinematics. Simple, cable-driven experimental set-ups have been widely adopted because they require little infrastructure. Traditionally, "fixed ring" cable-driven experimental designs have been used; however, there have been concerns with the validity of this set-up in applying pure moment loading. This study involved directly comparing the loading state induced by a traditional "fixed ring" apparatus versus a novel "sliding ring" approach. Flexion-extension bending was performed on an artificial spine model and a single cadaveric test specimen, and the applied loading conditions to the specimen were measured with an in-line multiaxial load cell. The results showed that the fixed ring system applies flexion-extension moments that are 50-60% less than the intended values. This design also imposes non-trivial anterior-posterior shear forces, and non-uniform loading conditions were induced along the length of the specimen. The results of this study indicate that fixed ring systems have the potential to deviate from a pure moment loading state and that our novel sliding ring modification corrects this error in the original test design. This suggests that the proposed sliding ring design should be used for future in vitro spine biomechanics studies involving a cable-driven pure moment apparatus. Copyright 2010 Elsevier Ltd. All rights reserved.

Single-pass BPM system of the Photon Factory storage ring.

PubMed

Honda, T; Katoh, M; Mitsuhashi, T; Ueda, A; Tadano, M; Kobayashi, Y

1998-05-01

At the 2.5 GeV ring of the Photon Factory, a single-pass beam-position monitor (BPM) system is being prepared for the storage ring and the beam transport line. In the storage ring, the injected beam position during the first several turns can be measured with a single injection pulse. The BPM system has an adequate performance, useful for the commissioning of the new low-emittance lattice. Several stripline BPMs are being installed in the beam transport line. The continuous monitoring of the orbit in the beam transport line will be useful for the stabilization of the injection energy as well as the injection beam orbit.

V-band electronically reconfigurable metamaterial

NASA Astrophysics Data System (ADS)

Radisic, Vesna; Hester, Jimmy G.; Nguyen, Vinh N.; Caira, Nicholas W.; DiMarzio, Donald; Hilgeman, Theodore; Larouche, Stéphane; Kaneshiro, Eric; Gutierrez-Aitken, Augusto

2017-04-01

In this work, we report on a reconfigurable V-band metamaterial fabricated using an InP heterojunction bipolar transistor production process. As designed and fabricated, the implementation uses complementary split ring resonators (cSRRs) and Schottky diodes in both single unit cell and three unit cell monolithic microwave integrated circuits. Each unit cell has two diodes embedded within the gaps of the cSRRs. Reconfigurability is achieved by applying an external bias that turns the diodes on and off, which effectively controls the resonant property of the structure. In order to measure the metamaterial properties, the unit cells are fed and followed by transmission lines. Measured data show good agreement with simulations and demonstrate that the metamaterial structure exhibits resonance at around 65 GHz that can be switched on and off. The three-unit cell transmission line metamaterial shows a deeper resonance and a larger phase change than a single cell, as expected. These are the first reported reconfigurable metamaterials operating at the V-band using the InP high speed device fabrication process.

Next generation HOM-damping

NASA Astrophysics Data System (ADS)

Marhauser, Frank

2017-06-01

Research and development for superconducting radio-frequency cavities has made enormous progress over the last decades from the understanding of theoretical limitations to the industrial mass fabrication of cavities for large-scale particle accelerators. Key technologies remain hot topics due to continuously growing demands on cavity performance, particularly when in pursuit of high quality beams at higher beam currents or higher luminosities than currently achievable. This relates to higher order mode (HOM) damping requirements. Meeting the desired beam properties implies avoiding coupled multi-bunch or beam break-up instabilities depending on the machine and beam parameters that will set the acceptable cavity impedance thresholds. The use of cavity HOM-dampers is crucial to absorb the wakefields, comprised by all beam-induced cavity Eigenmodes, to beam-dynamically safe levels and to reduce the heat load at cryogenic temperature. Cavity damping concepts may vary, but are principally based on coaxial and waveguide couplers as well as beam line absorbers or any combination. Next generation energy recovery linacs and circular colliders call for cavities with strong HOM-damping that can exceed the state-of-the-art, while the operating mode efficiency shall not be significantly compromised concurrently. This imposes major challenges given the rather limited damping concepts. A detailed survey of established cavities is provided scrutinizing the achieved damping performance, shortcomings, and potential improvements. The scaling of the highest passband mode impedances is numerically evaluated in dependence on the number of cells for a single-cell up to a nine-cell cavity, which reveals the increased probability of trapped modes. This is followed by simulations for single-cell and five-cell cavities, which incorporate multiple damping schemes to assess the most efficient concepts. The usage and viability of on-cell dampers is elucidated for the single-cell cavity since it can push the envelope towards quasi HOM-free operation suited for next generation storage and collider rings. Geometrical end-cell shape alterations for the five-cell cavity with already efficient mode damping are discussed as a possibility to further lower specific high impedance modes. The findings are eventually put into relation with demanding impedance instability thresholds in future collider rings.

Next generation HOM-damping

DOE PAGES

Marhauser, Frank

2017-05-15

Research and development for superconducting radio-frequency cavities has made enormous progress over the last decades from the understanding of theoretical limitations to the industrial mass fabrication of cavities for large-scale particle accelerators. Key technologies remain hot topics due to continuously growing demands on cavity performance, particularly when in pursuit of high quality beams at higher beam currents or higher luminosities than currently achievable. This relates to Higher Order Mode (HOM) damping requirements. Meeting the desired beam properties implies avoiding coupled multi-bunch or beam break-up instabilities depending on the machine and beam parameters that will set the acceptable cavity impedance thresholds.more » The use of cavity HOM-dampers is crucial to absorb the wakefields, comprised by all beam-induced cavity Eigenmodes, to beam-dynamically safe levels and to reduce the heat load at cryogenic temperature. Cavity damping concepts may vary, but are principally based on coaxial and waveguide couplers as well as beam line absorbers or any combination. Next generation Energy Recovery Linacs and circular colliders call for cavities with strong HOM-damping that can exceed the state-of-the-art, while the operating mode efficiency shall not be significantly compromised concurrently. This imposes major challenges given the rather limited damping concepts. A detailed survey of established cavities is provided scrutinizing the achieved damping performance, shortcomings, and potential improvements. The scaling of the highest passband mode impedances is numerically evaluated in dependence on the number of cells for a single-cell up to a nine-cell cavity, which reveals the increased probability of trapped modes. This is followed by simulations for single-cell and five-cell cavities, which incorporate multiple damping schemes to assess the most efficient concepts. The usage and viability of on-cell dampers is elucidated for the single-cell cavity since it can push the envelope towards quasi HOM-free operation suited for next generation storage and collider rings. Geometrical end-cell shape alterations for the five-cell cavity with already efficient mode damping are discussed as a possibility to further lower specific high impedance modes. Lastly, the findings are eventually put into relation with demanding impedance instability thresholds in future collider rings.« less

Non-Linear Dynamics of Saturn’s Rings

NASA Astrophysics Data System (ADS)

Esposito, Larry W.

2015-11-01

Non-linear processes can explain why Saturn’s rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states.Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit.Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like ‘straw’ that can explain the halo structure and spectroscopy: This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km).Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing.Ring dynamics and history implications: Moon-triggered clumping at perturbed regions in Saturn’s rings creates both high velocity dispersion and large aggregates at these distances, explaining both small and large particles observed there. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating the Markov chain as an asymmetric random walk with reflecting boundaries allows us to determine the power law index from results of numerical simulations in the tidal environment surrounding Saturn. Aggregates can explain many dynamic aspects of the rings and can renew rings by shielding and recycling the material within them, depending on how long the mass is sequestered. We can ask: Are Saturn’s rings a chaotic non-linear driven system?

Non-Linear Dynamics of Saturn's Rings

NASA Astrophysics Data System (ADS)

Esposito, L. W.

2015-12-01

Non-linear processes can explain why Saturn's rings are so active and dynamic. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw', as observed ny Cassini cameras. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon-triggered clumping at perturbed regions in Saturn's rings creates both high velocity dispersion and large aggregates at these distances, explaining both small and large particles observed there. This confirms the triple architecture of ring particles: a broad size distribution of particles; these aggregate into temporary rubble piles; coated by a regolith of dust. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating the Markov chain as an asymmetric random walk with reflecting boundaries allows us to determine the power law index from results of numerical simulations in the tidal environment surrounding Saturn. Aggregates can explain many dynamic aspects of the rings and can renew rings by shielding and recycling the material within them, depending on how long the mass is sequestered. We can ask: Are Saturn's rings a chaotic non-linear driven system?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kahlenberg, Volker; Konzett, Juergen; Kaindl, Reinhard

High-pressure synthesis experiments in the system Na{sub 2}O-Y{sub 2}O{sub 3}-SiO{sub 2} revealed the existence of a previously unknown polymorph of NaYSi{sub 2}O{sub 6} or Na{sub 3}Y{sub 3}[Si{sub 3}O{sub 9}]{sub 2} which was quenched from 3.0 GPa and 1000 deg. C. Structural investigations on this modification have been performed using single-crystal X-ray diffraction data collected at ambient conditions. Furthermore, unpolarized micro-Raman spectra have been obtained from single-crystal material. The high-P modification of NaYSi{sub 2}O{sub 6} crystallizes in the centrosymmetric space group C2/c with 12 formula units per cell (a=8.2131(9) A, b=10.3983(14) A, c=17.6542(21) A, {beta}=100.804(9){sup o}, V=1481.0(3) A{sup 3}, R(|F|)=0.033 formore » 1142 independent observed reflections) and belongs to the group of cyclo-silicates. Basic building units are isolated three-membered [Si{sub 3}O{sub 9}] rings located in layers parallel to (010). Within a single layer the rings are concentrated in strings parallel to [100]. The sequence of directedness of up (U) or down (D) pointing tetrahedra of a single ring is UUU or DDD, respectively. Stacking of the layers parallel to b results in the formation of a three-dimensional structure in which yttrium and sodium cations are incorporated for charge compensation. In more detail, four non-tetrahedral cation positions can be differentiated which are coordinated by 6 and 8 oxygen ligands. Refinements of the site occupancies did not reveal any indication for mixed Na-Y populations on these positions. Finally, several geometrical parameters of rings occurring in cyclo-trisilicate structures have been compiled and are discussed. - Graphical abstract: Projection of the whole structure of high-P NaYSi{sub 2}O{sub 6} parallel to [100].« less

Cylindrical cellular geometry ensures fidelity of division site placement in fission yeast.

PubMed

Mishra, Mithilesh; Huang, Yinyi; Srivastava, Pragya; Srinivasan, Ramanujam; Sevugan, Mayalagu; Shlomovitz, Roie; Gov, Nir; Rao, Madan; Balasubramanian, Mohan

2012-08-15

Successful cytokinesis requires proper assembly of the contractile actomyosin ring, its stable positioning on the cell surface and proper constriction. Over the years, many of the key molecular components and regulators of the assembly and positioning of the actomyosin ring have been elucidated. Here we show that cell geometry and mechanics play a crucial role in the stable positioning and uniform constriction of the contractile ring. Contractile rings that assemble in locally spherical regions of cells are unstable and slip towards the poles. By contrast, actomyosin rings that assemble on locally cylindrical portions of the cell under the same conditions do not slip, but uniformly constrict the cell surface. The stability of the rings and the dynamics of ring slippage can be described by a simple mechanical model. Using fluorescence imaging, we verify some of the quantitative predictions of the model. Our study reveals an intimate interplay between geometry and actomyosin dynamics, which are likely to apply in a variety of cellular contexts.

High-power actively Q-switched single-mode 1342 nm Nd:YVO₄ ring laser, injection-locked by a cw single-frequency microchip laser.

PubMed

Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A

2015-11-30

In this paper we report on the realization of a single-mode Q-switched Nd:YVO₄ ring laser at 1342 nm. Unidirectional and single-mode operation of the ring laser is achieved by injection-locking with a continuous wave Nd:YVO₄ microchip laser, emitting a single-frequency power of up to 40 mW. The ring laser provides a single-mode power of 13.9 W at 10 kHz pulse repetition frequency with a pulse duration of 18.2 ns and an excellent beam quality (M² < 1.05). By frequency doubling of the fundamental 1342 nm laser, a power of 8.7 W at 671 nm with a pulse duration of 14.8 ns and a beam propagation factor of M² < 1.1 is obtained. The 671 nm radiation features a long-term spectral width of 75 MHz.

In silico predictions of LH2 ring sizes from the crystal structure of a single subunit using molecular dynamics simulations.

PubMed

Janosi, Lorant; Keer, Harindar; Cogdell, Richard J; Ritz, Thorsten; Kosztin, Ioan

2011-07-01

Most of the currently known light-harvesting complexes 2 (LH2) rings are formed by 8 or 9 subunits. As of now, questions like "what factors govern the LH2 ring size?" and "are there other ring sizes possible?" remain largely unanswered. Here, we investigate by means of molecular dynamics (MD) simulations and stochastic modeling the possibility of predicting the size of an LH2 ring from the sole knowledge of the high resolution crystal structure of a single subunit. Starting with single subunits of two LH2 rings with known size, that is, an 8-ring from Rs. moliscianum (MOLI) and a 9-ring from Rps. acidophila (ACI), and one with unknown size (referred to as X), we build atomic models of subunit dimers corresponding to assumed 8-, 9-, and 10-ring geometries. After inserting each of the dimers into a lipid-water environment, we determine the preferred angle between the corresponding subunits by three methods: (1) energy minimization, (2) free MD simulations, and (3) potential of mean force calculations. We find that the results from all three methods are consistent with each other, and when taken together, it allows one to predict with reasonable level of confidence the sizes of the corresponding ring structures. One finds that X and ACI very likely form a 9-ring, while MOLI is more likely to form an 8-ring than a 9-ring. Finally, we discuss both the merits and limitations of all three prediction methods. Copyright © 2011 Wiley-Liss, Inc.

Signet-ring cell lymphoma: clinicopathologic, immunohistochemical, and fluorescence in situ hybridization studies of 7 cases.

PubMed

Zhang, Shanxiang; Sun, Jihong; Fang, Yanan; Nassiri, Mehdi; Liu, Lanting; Zhou, Jiehao; Stohler, Ryan; Choi, Haki; Vance, Gail H

2017-02-01

Signet-ring cell lymphoma (SRCL) is a rare morphologic variant of non-Hodgkin lymphoma. Although it was initially reported as a rare morphologic variant of follicular lymphoma (FL), SRCL has to date been described in most types of non-Hodgkin lymphoma, mostly as single-case reports. To study SRCL systematically by immunohistochemical stains and fluorescent in situ hybridization analyses. Seven SRCL cases were stained for CD3, CD5, CD20, PAX-5, CD10, CD21, CD23, cyclin D1, BCL2, BCL6, Ki-67, and MUM-1, and were analyzed by fluorescent in situ hybridization for BCL2, BCL6, MYC, and MALT1 rearrangements. Clinical information and patient outcome were reviewed in all patients. The patients were 3 women and 3 men, ranging in age from 31 to 75 years (average 60.3 years). The lesions involved lymph nodes, tonsil, parotid gland, soft tissue, and breast. There were 4 FLs, 1 diffuse large B-cell lymphoma (DLBCL), 1 DLBCL with FL, and 1 DLBCL with marginal zone lymphoma. All cases had typical signet-ring cell morphology. They were positive for CD20 and BCL-2, and had low-to-intermediate Ki-67 proliferation index (10%-40%) except in the parotid DLBCL with FL (70%). BCL-6 was detected in all but 1 FL (6/7). Fluorescent in situ hybridization detected IGH/BCL2 translocation in 1 FL, increased BCL6 copy number in another FL, BCL6 rearrangement, and increased copy number of MYC and MALT1 in the DLBCL with marginal zone lymphoma. The FL with signet-ring cell morphology (1/5) tends to lack IGH/BCL2 translocation, and an extended immunohistochemical study is recommended for correct diagnosis and classification of SRCL. Copyright © 2016 Elsevier Inc. All rights reserved.

Using multi-ring structure for suppression of mode competition in stable single-longitudinal-mode erbium fiber laser

NASA Astrophysics Data System (ADS)

Yeh, Chien-Hung; Huang, Tzu-Jung; Yang, Zi-Qing; Chow, Chi-Wai

2017-12-01

In this demonstration, a stable and tunable single-longitudinal-mode (SLM) erbium-doped fiber (EDF) laser with multiple-ring configuration is proposed and investigated. The proposed compound-ring structure can create different free spectrum ranges (FSRs) to result in the mode-filter effect based on the Vernier effect for suppressing the other modes. Additionally, the output stabilization of power and wavelength in the proposed EDF multiple-ring laser are also discussed.

Superfluid qubit systems with ring shaped optical lattices

PubMed Central

Amico, Luigi; Aghamalyan, Davit; Auksztol, Filip; Crepaz, Herbert; Dumke, Rainer; Kwek, Leong Chuan

2014-01-01

We study an experimentally feasible qubit system employing neutral atomic currents. Our system is based on bosonic cold atoms trapped in ring-shaped optical lattice potentials. The lattice makes the system strictly one dimensional and it provides the infrastructure to realize a tunable ring-ring interaction. Our implementation combines the low decoherence rates of neutral cold atoms systems, overcoming single site addressing, with the robustness of topologically protected solid state Josephson flux qubits. Characteristic fluctuations in the magnetic fields affecting Josephson junction based flux qubits are expected to be minimized employing neutral atoms as flux carriers. By breaking the Galilean invariance we demonstrate how atomic currents through the lattice provide an implementation of a qubit. This is realized either by artificially creating a phase slip in a single ring, or by tunnel coupling of two homogeneous ring lattices. The single qubit infrastructure is experimentally investigated with tailored optical potentials. Indeed, we have experimentally realized scaled ring-lattice potentials that could host, in principle, n ~ 10 of such ring-qubits, arranged in a stack configuration, along the laser beam propagation axis. An experimentally viable scheme of the two-ring-qubit is discussed, as well. Based on our analysis, we provide protocols to initialize, address, and read-out the qubit. PMID:24599096

Hermetically sealed electrical feedthrough for high temperature secondary cells

DOEpatents

Knoedler, R.; Nelson, P.A.; Shimotake, H.; Battles, J.E.

1983-07-26

A passthrough seal is disclosed for electrically isolating the terminal in a lithium/metal sulfide cell from the structural cell housing. The seal has spaced upper and lower insulator rings fitted snuggly between the terminal and an annularly disposed upstanding wall, and outwardly of a powdered insulator also confined between the upstanding wall and terminal. The adjacent surfaces of the upper insulator ring and the respective upstanding wall and terminal are conically tapered, diverging in the axial direction away from the cell interior, and a sealing ring is located between each pair of the adjacent surfaces. The components are sized so that upon appropriate movement of the upper insulator ring toward the lower insulator ring the powdered insulator and sealing rings are each compressed to a high degree. This compacts the powdered insulator thereby rendering the same highly impervious and moreover fuses the sealing rings to and between the adjacent surfaces. The upper and lower insulator rings might be formed of beryllium oxide and/or alumina, the powdered insulator might be formed of boron nitride, and the sealing rings might be formed of aluminum.

Hermetically sealed electrical feedthrough for high temperature secondary cells

DOEpatents

Knoedler, Reinhard; Nelson, Paul A.; Shimotake, Hiroshi; Battles, James E.

1985-01-01

A passthrough seal is disclosed for electrically isolating the terminal in a lithium/metal sulfide cell from the structural cell housing. The seal has spaced upper and lower insulator rings fitted snuggly between the terminal and an annularly disposed upstanding wall, and outwardly of a powdered insulator also confined between the upstanding wall and terminal. The adjacent surfaces of the upper insulator ring and the respective upstanding wall and terminal are conically tapered, diverging in the axial direction away from the cell interior, and a sealing ring is located between each pair of the adjacent surfaces. The components are sized so that upon appropriate movement of the upper insulator ring toward the lower insulator ring the powdered insulator and sealing rings are each compressed to a high degree. This compacts the powdered insulator thereby rendering the same highly impervious and moreover fuses the sealing rings to and between the adjacent surfaces. The upper and lower insulator rings might be formed of beryllium oxide and/or alumina, the powdered insulator might be formed of boron nitride, and the sealing rings might be formed of aluminum.

The contractile ring coordinates curvature-dependent septum assembly during fission yeast cytokinesis.

PubMed

Zhou, Zhou; Munteanu, Emilia Laura; He, Jun; Ursell, Tristan; Bathe, Mark; Huang, Kerwyn Casey; Chang, Fred

2015-01-01

The functions of the actin-myosin-based contractile ring in cytokinesis remain to be elucidated. Recent findings show that in the fission yeast Schizosaccharomyces pombe, cleavage furrow ingression is driven by polymerization of cell wall fibers outside the plasma membrane, not by the contractile ring. Here we show that one function of the ring is to spatially coordinate septum cell wall assembly. We develop an improved method for live-cell imaging of the division apparatus by orienting the rod-shaped cells vertically using microfabricated wells. We observe that the septum hole and ring are circular and centered in wild-type cells and that in the absence of a functional ring, the septum continues to ingress but in a disorganized and asymmetric manner. By manipulating the cleavage furrow into different shapes, we show that the ring promotes local septum growth in a curvature-dependent manner, allowing even a misshapen septum to grow into a more regular shape. This curvature-dependent growth suggests a model in which contractile forces of the ring shape the septum cell wall by stimulating the cell wall machinery in a mechanosensitive manner. Mechanical regulation of the cell wall assembly may have general relevance to the morphogenesis of walled cells. © 2015 Zhou et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Possibility designing XNOR and NAND molecular logic gates by using single benzene ring

NASA Astrophysics Data System (ADS)

Abbas, Mohammed A.; Hanoon, Falah H.; Al-Badry, Lafy F.

2017-09-01

This study focused on examining electronic transport through single benzene ring and suggested how such ring can be employed to design XNOR and NAND molecular logic gates. The single benzene ring was threaded by a magnetic flux. The magnetic flux and applied gate voltages were considered as the key tuning parameter in the XNOR and NAND gates operation. All the calculations are achieved by using steady-state theoretical model, which is based on the time-dependent Hamiltonian model. The transmission probability and the electric current are calculated as functions of electron energy and bias voltage, respectively. The application of the anticipated results can be a base for the progress of molecular electronics.

Magnetic anisotropy of the antiferromagnetic ring [Cr8F8Piv16].

PubMed

van Slageren, Joris; Sessoli, Roberta; Gatteschi, Dante; Smith, Andrew A; Helliwell, Madeleine; Winpenny, Richard E P; Cornia, Andrea; Barra, Anne-Laure; Jansen, Aloysius G M; Rentschler, Eva; Timco, Grigore A

2002-01-04

A new tetragonal (P42(1)2) crystalline form of [Cr8F8Piv16] (HPiv = pivalic acid, trimethyl acetic acid) is reported. The ring-shaped molecules, which are aligned in a parallel fashion in the unit cell, form almost perfectly planar, regular octagons. The interaction between the CrIII ions is antiferromagnetic (J = 12 cm(-1)) which results in a S = 0 spin ground state. The low-lying spin excited states were investigated by cantilever torque magnetometry (CTM) and high-frequency EPR (HFEPR). The compound shows hard-axis anisotropy. The axial zero-field splitting (ZFS) parameters of the first two spin excited states (S = 1 and S = 2, respectively) are D1 = 1.59(3) cm(-1) or 1.63 cm(-1) (from CTM and HFEPR, respectively) and D2 = 0.37 cm(-1) (from HFEPR). The dipolar contributions to the ZFS of the S = 1 and S = 2 spin states were calculated with the point dipolar approximation. These contributions proved to be less than the combined single-ion contributions. Angular overlap model calculations that used parameters obtained from the electronic absorption spectrum, showed that the unique axis of the single-ion ZFS is at an angle of 19.3(1) degrees with respect to the ring axis. The excellent agreement between the experimental and the theoretical results show the validity of the used methods for the analysis of the magnetic anisotropy in antiferromagnetic CrIII rings.

Distinguishing between whole cells and cell debris using surface plasmon coupled emission (Conference Presentation)

NASA Astrophysics Data System (ADS)

Talukder, Muhammad A.; Menyuk, Curtis R.; Kostov, Yordan

2017-02-01

Distinguishing between intact cells, dead but still whole cells, and cell debris is an important but difficult task in life sciences. The most common way to identify dead cells is using a cell-impermeant DNA binding dye, such as propidium iodide. A healthy living cell has an intact cell membrane and will act as a barrier to the dye so that it cannot enter the cell. A dead cell has a compromised cell membrane, and it will allow the dye into the cell to bind to the DNA and become fluorescent. The dead cells therefore will be positive and the live cells will be negative. The dead cells later deteriorate quickly into debris. Different pieces of debris from a single cell can be incorrectly identified as separate dead cells. Although a flow cytometer can quickly perform numerous quantitative, sensitive measurements on each individual cell to determine the viability of cells within a large, heterogeneous population, it is bulky, expensive, and only large hospitals and laboratories can afford them. In this work, we show that the distance-dependent coupling of fluorophore light to surface plasmon coupled emission (SPCE) from fluorescently-labeled cells can be used to distinguish whole cells from cell debris. Once the fluorescent labels are excited by a laser, the fluorescently-labeled whole cells create two distinct intensity rings in the far-field, in contrast to fluorescently-labeled cell debris, which only creates one ring. The distinct far-field patterns can be captured by camera and used to distinguish between whole cells and cell debris.

Crab Cavity and Cryomodule Prototype Development for the Advanced Photon Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, H; Ciovati, G; Clemens, W A

2011-03-01

We review the single-cell, superconducting crab cavity designs for the short-pulse x-ray (SPX) project at the Advanced Photon Source (APS). The 'on-cell' waveguide scheme is expected to have a more margin for the impedance budget of the APS storage ring, as well as offering a more compact design compared with the original design consisting of a low order mode damping waveguide on the beam pipe. We will report recent fabrication progress, cavity test performance on original and alternate prototypes, and concept designs and analysis for various cryomodule components.

Characterization of a Naphthalene Dioxygenase Endowed with an Exceptionally Broad Substrate Specificity Toward Polycyclic Aromatic Hydrocarbons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jouanneau,Y.; Meyer, C.; Jakoncic, J.

In Sphingomonas CHY-1, a single ring-hydroxylating dioxygenase is responsible for the initial attack of a range of polycyclic aromatic hydrocarbons (PAHs) composed of up to five rings. The components of this enzyme were separately purified and characterized. The oxygenase component (ht-PhnI) was shown to contain one Rieske-type [2Fe-2S] cluster and one mononuclear Fe center per {alpha} subunit, based on EPR measurements and iron assay. Steady-state kinetic measurements revealed that the enzyme had a relatively low apparent Michaelis constant for naphthalene (K{sub m} = 0.92 {+-} 0.15 {mu}M) and an apparent specificity constant of 2.0 {+-} 0.3 M{sup -1} s{sup -1}.more » Naphthalene was converted to the corresponding 1,2-dihydrodiol with stoichiometric oxidation of NADH. On the other hand, the oxidation of eight other PAHs occurred at slower rates and with coupling efficiencies that decreased with the enzyme reaction rate. Uncoupling was associated with hydrogen peroxide formation, which is potentially deleterious to cells and might inhibit PAH degradation. In single turnover reactions, ht-PhnI alone catalyzed PAH hydroxylation at a faster rate in the presence of organic solvent, suggesting that the transfer of substrate to the active site is a limiting factor. The four-ring PAHs chrysene and benz[a]anthracene were subjected to a double ring-dihydroxylation, giving rise to the formation of a significant proportion of bis-cis-dihydrodiols. In addition, the dihydroxylation of benz[a]anthracene yielded three dihydrodiols, the enzyme showing a preference for carbons in positions 1,2 and 10,11. This is the first characterization of a dioxygenase able to dihydroxylate PAHs made up of four and five rings.« less

Mechanical Regulation in Cell Division and in Neurotransmitter Release

NASA Astrophysics Data System (ADS)

Thiyagarajan, Sathish

During their lifecycle, cells must produce forces which play important roles in several subcellular processes. Force-producing components are organized into macromolecular assemblies of proteins that are often dynamic, and are constructed or disassembled in response to various signals. The forces themselves may directly be involved in subcellular mechanics, or they may influence mechanosensing proteins either within or outside these structures. These proteins play different roles: they may ensure the stability of the force-producing structure, or they may send signals to a coupled process. The generation and sensing of subcellular forces is an active research topic, and this thesis focusses on the roles of these forces in two key areas: cell division and neurotransmitter release. The first part of the thesis deals with the effect of force on cell wall growth regulation during division in the fission yeast Schizosaccharomyces pombe, a cigar-shaped, unicellular organism. During cytokinesis, the last stage of cell division in which the cell physically divides into two, a tense cytokinetic ring anchored to the cellular membrane assembles and constricts, accompanied by the inward centripetal growth of new cell wall, called septum, in the wake of the inward-moving membrane. The contour of the septum hole maintains its circularity as it reduces in size--an indication of regulated growth. To characterize the cell wall growth process, we performed image analysis on contours of the leading edge of the septum obtained via fluorescence microscopy in the labs of our collaborators. We quantified the deviations from circularity using the edge roughness. The roughness was spatially correlated, suggestive of regulated growth. We hypothesized that the cell wall growers are mechanosensitive and respond to the force exerted by the ring. A mathematical model based on this hypothesis then showed that this leads to corrections of roughness in a curvature-dependent fashion. Thus, one of the roles of ring tension is to communicate with the mechanosensitive septum growth processes and coordinate growth to ensure the daughter cells have a functional cell wall. The second part of the thesis deals with how ring tension is produced and sustained, using experimentally measured ultrastructure of the cytokinetic ring itself. Recent super-resolution experiments have revealed that several key proteins of the fission yeast constricting ring are organized into membrane-anchored complexes called nodes. The force producing protein myosin-II in these nodes exerts pulling forces on polymeric actin filaments that are synthesized from polymerizers residing in the nodes. How these forces are marshalled to generate ring tension, and how such an organization maintains its stability is unclear. Using a mathematical model with coarse-grained representations of actin and myosin, we showed that such a node-based organization reproduces previously measured ring tension values. The model explains the origin of experimentally observed bidirectional motion of the nodes in the ring, and showed that turnover of the nodes rescues the ring from inherent contractile instabilities that would be expected when a force-producing structure is made up of small object that effectively attract one another. Finally, the third part of the thesis deals with the role of forces produced by SNARE proteins at synapses between two neurons during neurotransmission. A key step here is synaptic release, where inside a neuron, membrane-bound compartments called vesicles filled with neurotransmitter fuse with the membrane of the neuron forming a transient fusion pore, and release their contents to the outside of the cell. These neurotransmitter molecules are sensed by another neuron that is physically separate from the neuron in question and this neuron propagates the signal henceforth. Thus, regulation of neurotransmitter release is a key step in neurotransmission. A fusion machinery consisting of several proteins facilitates membrane fusion, and pore nucleation requires the formation of a SNARE protein complex in this machinery, whose role during pore dilation is unclear. Using electrophysiological measurements, our collaborators experimentally measured the statistics of the size of single fusion pores in vitro, and observed that average pore sizes increased with the number of SNARE proteins. Using mathematical modeling, we showed that this effect was due to an entropic crowding force that expands the pore and increases with the number of SNAREs, and counteracts the energy barrier to fusion pore expansion.

Ion distribution in quaternary-ammonium-functionalized aromatic polymers: effects on the ionic clustering and conductivity of anion-exchange membranes.

PubMed

Weiber, E Annika; Jannasch, Patric

2014-09-01

A series of copoly(arylene ether sulfone)s that have precisely two, three, or four quaternary ammonium (QA) groups clustered directly on single phenylene rings along the backbone are studied as anion-exchange membranes. The copolymers are synthesized by condensation polymerizations that involve either di-, tri-, or tetramethylhydroquinone followed by virtually complete benzylic bromination using N-bromosuccinimide and quaternization with trimethylamine. This synthetic strategy allows excellent control and systematic variation of the local density and distribution of QA groups along the backbone. Small-angle X-ray scattering of these copolymers shows extensive ionic clustering, promoted by an increasing density of QA on the single phenylene rings. At an ion-exchange capacity (IEC) of 2.1 meq g(-1), the water uptake decreases with the increasing local density of QA groups. Moreover, at moderate IECs at 20 °C, the Br(-) conductivity of the densely functionalized copolymers is higher than a corresponding randomly functionalized polymer, despite the significantly higher water uptake of the latter. Thus, the location of multiple cations on single aromatic rings in the polymers facilitates the formation of a distinct percolating hydrophilic phase domain with a high ionic concentration to promote efficient anion transport, despite probable limitations by reduced ion dissociation. These findings imply a viable strategy to improve the performance of alkaline membrane fuel cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Z ring as executor of bacterial cell division.

PubMed

Dajkovic, Alex; Lutkenhaus, Joe

2006-01-01

It has become apparent that bacteria possess ancestors of the major eukaryotic cytoskeletal proteins. FtsZ, the ancestral homologue of tubulin, assembles into a cytoskeletal structure associated with cell division, designated the Z ring. Formation of the Z ring represents a major point of both spatial and temporal regulation of cell division. Here we discuss findings concerning the structure and the formation of the ring as well as its spatial and temporal regulation.

Primary Lung Signet Ring Cell Carcinoma Presenting as a Cavitary Pancoast Tumor in a 32-Year-Old Man.

PubMed

Corvini, Michael; Koorji, Alysha; Sgroe, Erica; Nguyen, Uyen

2018-06-01

Signet ring cell carcinoma, a subtype of adenocarcinoma, is a rare cause of primary lung cancer. The authors report a case of primary lung signet ring cell carcinoma presenting as a cavitary Pancoast tumor in a 32-year-old male smoker. Beyond the rarity of primary lung signet ring cell carcinoma itself, the youth of the patient, his smoking status, the presence of cavitation, and the location of the tumor in the superior sulcus make it especially atypical.

Lubrication of 35-millimeter-bore ball bearings of several designs to 2.5 million DN

NASA Technical Reports Server (NTRS)

Schuller, F. T.

1983-01-01

Parametric tests were conducted with 35mm bore, angular contact ball bearings with either a single or double outer and guided cage. The bearings were either lubricated by oil jets or employed inner ring lubrication. Outer ring cooling was added in selected tests. Lubricant flow to the bearing ranged from 300 to 1900 cc/min. All bearings were successfully run at speeds to 2.5 million DN. Increasing the lubricant flow decreased bearing ring temperatures but increased bearing power lines. The power loss and race temperatures of a jet lubricated with double outer land guided cage were always higher than those of the single land guided design at similar test conditions. The lowest bearing operating temperatures were achieved when inner ring lubrication and outer ring cooling were combined. It is found that cage slip of a double outer land guided cage is approximately twice that of a single outer land guided cage.

Substrate-controlled Rh(II)-catalyzed single-electron-transfer (SET): divergent synthesis of fused indoles.

PubMed

Chen, Kai; Zhu, Zi-Zhong; Liu, Jia-Xin; Tang, Xiang-Ying; Wei, Yin; Shi, Min

2016-01-07

Rh(II)-catalyzed diversified ring expansions controlled by single-electron-transfer (SET) have been disclosed in this communication, producing a series of indole-fused azetidines and 1H-carbazoles or related derivatives in moderate to good yields via Rh2(III,II) nitrene radical intermediates. The direction of ring expansion branches according to different ring sizes of methylenecycloalkanes.

Costly Cell Phones: The Impact of Cell Phone Rings on Academic Performance

ERIC Educational Resources Information Center

End, Christian M.; Worthman, Shaye; Mathews, Mary Bridget; Wetterau, Katharina

2010-01-01

College students participated in a study on the "psychology of note taking" during which they took notes on video content and later completed a multiple-choice test on the material. Researchers assigned 71 participants to either the ringing condition (the video was disrupted by a ringing cell phone) or the control condition (no cell phone rings…

Type II GaSb quantum ring solar cells under concentrated sunlight.

PubMed

Tsai, Che-Pin; Hsu, Shun-Chieh; Lin, Shih-Yen; Chang, Ching-Wen; Tu, Li-Wei; Chen, Kun-Cheng; Lay, Tsong-Sheng; Lin, Chien-chung

2014-03-10

A type II GaSb quantum ring solar cell is fabricated and measured under the concentrated sunlight. The external quantum efficiency confirms the extended absorption from the quantum rings at long wavelength coinciding with the photoluminescence results. The short-circuit current of the quantum ring devices is 5.1% to 9.9% more than the GaAs reference's under various concentrations. While the quantum ring solar cell does not exceed its GaAs counterpart in efficiency under one-sun, the recovery of the open-circuit voltages at higher concentration helps to reverse the situation. A slightly higher efficiency (10.31% vs. 10.29%) is reported for the quantum ring device against the GaAs one.

Stabilized single-longitudinal-mode erbium fibre laser employing silicon-micro-ring resonator and saturable absorber

NASA Astrophysics Data System (ADS)

Hsu, Yung; Yeh, Chien-Hung; Chow, Chi-Wai; Chang, Yuan-Chia; Cheng, Hao-Yun

2018-07-01

In the paper, a wavelength-tunable erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) oscillation is proposed and investigated. Here, a silicon-micro-ring-resonator can be applied in a laser cavity for tuning wavelength in the C-band range. To complete the SLM oscillation, an unpumped EDF-based saturable absorber is used to act as ultra-narrowband filter for suppressing other oscillation modes. Additionally, the output stabilities of power and wavelength in the proposed EDF ring laser are also executed and discussed.

Intravaginal ring delivery of the reverse transcriptase inhibitor TMC 120 as an HIV microbicide.

PubMed

Woolfson, A David; Malcolm, R Karl; Morrow, Ryan J; Toner, Clare F; McCullagh, Stephen D

2006-11-15

TMC 120 (Dapivirine) is a potent non-nucleoside reverse transcriptase inhibitor that is presently being developed as a vaginal HIV microbicide. To date, most vaginal microbicides under clinical investigation have been formulated as single-dose semi-solid gels, designed for application to the vagina before each act of intercourse. However, a clear rationale exists for providing long-term, controlled release of vaginal microbicides in order to afford continuous protection against heterosexually transmitted HIV infection and to improve user compliance. In this study we report on the incorporation of various pharmaceutical excipients into TMC 120 silicone, reservoir-type intravaginal rings (IVRs) in order to modify the controlled release characteristics of the microbicide. The results demonstrate that TMC 120 is released in zero-order fashion from the rings over a 28-day period and that release parameters could be modified by the inclusion of release-modifying excipients in the IVR. The hydrophobic liquid excipient isopropyl myristate had little effect on steady-state daily release rates, but did increase the magnitude and duration of burst release in proportion to excipient loading in the IVR. By comparison, the hydrophobic liquid poly(dimethylsiloxane) had little effect on TMC 120 release parameters. A hydrophilic excipient, lactose, had the surprising effect of decreasing TMC 120 burst release while increasing the apparent steady-state daily release in a concentration-dependent manner. Based on previous cell culture data and vaginal physiology, TMC120 is released from the various ring formulations in amounts potentially capable of maintaining a protective vaginal concentration. It is further predicted that the observed release rates may be maintained for at least a period of 1 year from a single ring device. TMC 120 release profiles and the mechanical properties of rings could be modified by the physicochemical nature of hydrophobic and hydrophilic excipients incorporated into the IVRs.

Non-Linear Dynamics of Saturn's Rings

NASA Astrophysics Data System (ADS)

Esposito, L. W.

2016-12-01

Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. Stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, that push the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like `straw' that can explain the halo morphology and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; this requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km).Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing.Ring dynamics and history implications: Moon-triggered clumping explains both small and large particles at resonances. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating it as an asymmetric random walk with reflecting boundaries determines the power law index, using results of numerical simulations in the tidal environment. Aggregates can explain many dynamic aspects of the rings and can renew rings by shielding and recycling the material within them, depending on how long the mass is sequestered. We can ask: Are Saturn's rings a chaotic non-linear driven system?

Optimal control of quantum rings by terahertz laser pulses.

PubMed

Räsänen, E; Castro, A; Werschnik, J; Rubio, A; Gross, E K U

2007-04-13

Complete control of single-electron states in a two-dimensional semiconductor quantum-ring model is established, opening a path into coherent laser-driven single-gate qubits. The control scheme is developed in the framework of optimal-control theory for laser pulses of two-component polarization. In terms of pulse lengths and target-state occupations, the scheme is shown to be superior to conventional control methods that exploit Rabi oscillations generated by uniform circularly polarized pulses. Current-carrying states in a quantum ring can be used to manipulate a two-level subsystem at the ring center. Combining our results, we propose a realistic approach to construct a laser-driven single-gate qubit that has switching times in the terahertz regime.

Identification of putative Z-ring-associated proteins, involved in cell division in human pathogenic bacteria Helicobacter pylori.

PubMed

Kamran, Mohammad; Sinha, Swati; Dubey, Priyanka; Lynn, Andrew M; Dhar, Suman K

2016-07-01

Cell division in bacteria is initiated by FtsZ, which forms a Z ring at the middle of the cell, between the nucleoids. The Z ring is stabilized by Z ring-associated proteins (Zaps), which crosslink the FtsZ filaments and provide strength. The deletion of Zaps leads to the elongation phenotype with an abnormal Z ring. The components of cell division in Helicobacter pylori are similar to other gram negative bacteria except for the absence of few components including Zaps. Here, we used HHsearch to identify homologs of the missing cell division proteins and got potential hits for ZapA and ZapB, as well as for few other cell division proteins. We further validated the function of the putative ZapA homolog by genetic complementation, immuno-colocalization and biochemical analysis. © 2016 Federation of European Biochemical Societies.

Yeast cohesin complex embraces 2 micron plasmid sisters in a tri-linked catenane complex

PubMed Central

Ghosh, Santanu K.; Huang, Chu-Chun; Hajra, Sujata; Jayaram, Makkuni

2010-01-01

Sister chromatid cohesion, crucial for faithful segregation of replicated chromosomes in eukaryotes, is mediated by the multi-subunit protein complex cohesin. The Saccharomyces cerevisiae plasmid 2 micron circle mimics chromosomes in assembling cohesin at its partitioning locus. The plasmid is a multi-copy selfish DNA element that resides in the nucleus and propagates itself stably, presumably with assistance from cohesin. In metaphase cell lysates, or fractions enriched for their cohesed state by sedimentation, plasmid molecules are trapped topologically by the protein ring formed by cohesin. They can be released from cohesin’s embrace either by linearizing the DNA or by cleaving a cohesin subunit. Assays using two distinctly tagged cohesin molecules argue against the hand-cuff (an associated pair of monomeric cohesin rings) or the bracelet (a dimeric cohesin ring) model as responsible for establishing plasmid cohesion. Our cumulative results most easily fit a model in which a single monomeric cohesin ring, rather than a series of such rings, conjoins a pair of sister plasmids. These features of plasmid cohesion account for its sister-to-sister mode of segregation by cohesin disassembly during anaphase. The mechanistic similarities of cohesion between mini-chromosome sisters and 2 micron plasmid sisters suggest a potential kinship between the plasmid partitioning locus and centromeres. PMID:19920123

Microwave-assisted one-step patterning of aqueous colloidal silver.

PubMed

Yang, G; Zhou, Y W; Guo, Z R; Wan, Y; Ding, Q; Bai, T T; Wang, C L; Gu, N

2012-07-05

A new approach of utilizing microwave to pattern gradient concentric silver nanoparticle ring structures has been presented. The width and height of a single ring and the space between adjacent rings can be adjusted by changing the silver colloidal concentration and the microwave output power. By simply enhancing the ambient vapour pressure to the saturated value during microwave-assisted evaporation, sub-100 nm rings can be deposited in between adjacent micro-rings over a distance of millimetres. Combined with microwave sintering, this approach can also create conductive silver tracks in a single step, showing huge potential in fabricating micro- and nano-electronic devices in an ultra-fast and cost-effective fashion.

Derivation of two functional X chromosome centromeres from a single break bisecting the centromere of origin: Implications for centromere structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schonberg, S.A.; Quarles, C.; Tifft, C.

1994-09-01

The precise nature of the functional human centromeric sequences remains a matter of some controversy. Evidence has accumulated over the past several years that directly implicates alphoid repeats as a critical component. We report a child with dysmorphic features consistent with the recently described small ring X syndrome, with a constitutional karyotype that addresses this issue. At 5 1/2 months, the patient was a small, hypotonic, delayed female with brachycephaly, a broad forehead, prominent nasal root, synophorous, small mouth, and cup-shaped ears with prominent lobules, as well as microcornea, and pendular nystagmus. Hand abnormalities included single palmar creases and shortmore » tapered fingers. In addition to mosaicism for a small ring chromosome derived from the proximal short arm of the X, the proband has, in all cells, a monocentric isochromosome for the long arm of the X. The karyotype is interpreted as 46,X,iso(Xq)/47,X,iso(Xq),r(Xp11cen). We present routine karyotypic and FISH analysis of the rearranged X chromosomes. We propose that the only mechanism consistent with this karyotype is that of a two-break rearrangement with one break bisecting a centromere in such a way as to retain functional centromeric activity in each of the separated regions. The second break, proximal in the short arm, allows for ring chromosome formation with the bisected centromere. The iso(Xq) arises by the classical mechanism of post-replication sister-reunion. The formation of two functional centromeres by a single break through the {open_quotes}parental{close_quotes} centromere indicates that the functional activity must be in a repeated component of the centromeric DNA and argues strongly against the requirement for any single gene in cis orientation.« less

Self-assembly of InAs ring complexes on InP substrates by droplet epitaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noda, T.; Mano, T.; Jo, M.

We report the self-assembly of InAs ring complexes on InP (100) substrates by droplet epitaxy. Single-ring, ring-disk complex, and concentric double-ring structures were formed by controlling the As beam flux and substrate temperature. A clear photoluminescence signal was detected in a sample where InAs rings were embedded in InGaAs.

A new F-actin structure in fungi: actin ring formation around the cell nucleus of Cryptococcus neoformans.

PubMed

Kopecká, Marie; Kawamoto, Susumu; Yamaguchi, Masashi

2013-04-01

The F-actin cytoskeleton of Cryptococcus neoformans is known to comprise actin cables, cortical patches and cytokinetic ring. Here, we describe a new F-actin structure in fungi, a perinuclear F-actin collar ring around the cell nucleus, by fluorescent microscopic imaging of rhodamine phalloidin-stained F-actin. Perinuclear F-actin rings form in Cryptococcus neoformans treated with the microtubule inhibitor Nocodazole or with the drug solvent dimethyl sulfoxide (DMSO) or grown in yeast extract peptone dextrose (YEPD) medium, but they are absent in cells treated with Latrunculin A. Perinuclear F-actin rings may function as 'funicular cabin' for the cell nucleus, and actin cables as intracellular 'funicular' suspending nucleus in the central position in the cell and moving nucleus along the polarity axis along actin cables.

Bond-equilibrium theory of liquid Se-Te alloys. II. Effect of singly attached ring molecules

NASA Astrophysics Data System (ADS)

Cutler, Melvin; Bez, Wolfgang G.

1981-06-01

A statistical-mechanical theory for bond equilibrium of chain polymers containing threefold (3F) and onefold (1F) bond defects is extended to include the effects of free ring molecules and ring molecules attached to chains by a single 3F atom. Positively charged singly attached rings are shown to play a key role in bond equilibrium in liquid Sex Te1-x by permitting the formation of ion pairs in which both constituents are effectively chain terminators, thus decreasing the average polymer size. The theory is applied to explain the behavior of the paramagnetic susceptibility, χp, and electronic transport as affected by the Fermi energy EF. It is found that the increase in χp with the concentration of Te is primarily the result of the smaller energy for breaking Te bonds. In addition, attached rings play an important role in determining the effect of temperature on χp. At x<~0.5, the concentrations of both free and attached rings becomes small at high T because of the high concentration of bond defects.

A Novel CMOS Multi-band THz Detector with Embedded Ring Antenna

NASA Astrophysics Data System (ADS)

Xu, Lei-jun; Guan, Jia-ning; Bai, Xue; Li, Qin; Mao, Han-ping

2017-10-01

To overcome the large chip area occupation for the traditional terahertz multi-frequency detector by using the antenna elements in a different frequency, a novel structure for a multi-frequency detector is proposed and studied. Based on the ring antenna detector, an embedded multi-ring antenna with multi-port is proposed for the multi-frequency detector. A single-ring and dual-ring detectors are analyzed and designed in 0.18 μ m CMOS. For the single-ring detector, the best responsivity and NEP is 701 V/W and 261 pW/Hz0.5 at the frequency of 290 GHz. For the dual-ring detector, the best responsivity is 367 V/W and 297 V/W, NEP is 578 pW/Hz0.5 and 713pW/Hz0.5, at the frequency of 600 GHz and 806 GHz, respectively. This embedded multi-ring detector has a simple structure which can be expanded easily in a compact size.

Micrometer-scale fabrication of complex three dimensional lattice + basis structures in silicon

DOE PAGES

Burckel, D. Bruce; Resnick, Paul J.; Finnegan, Patrick S.; ...

2015-01-01

A complementary metal oxide semiconductor (CMOS) compatible version of membrane projection lithography (MPL) for fabrication of micrometer-scale three-dimensional structures is presented. The approach uses all inorganic materials and standard CMOS processing equipment. In a single layer, MPL is capable of creating all 5 2D-Bravais lattices. Furthermore, standard semiconductor processing steps can be used in a layer-by-layer approach to create fully three dimensional structures with any of the 14 3D-Bravais lattices. The unit cell basis is determined by the projection of the membrane pattern, with many degrees of freedom for defining functional inclusions. Here we demonstrate several unique structural motifs, andmore » characterize 2D arrays of unit cells with split ring resonators in a silicon matrix. The structures exhibit strong polarization dependent resonances and, for properly oriented split ring resonators (SRRs), coupling to the magnetic field of a normally incident transverse electromagnetic wave, a response unique to 3D inclusions.« less

Mucinous colorectal adenocarcinoma with signet-ring cells: immunohistochemical and ultrastructural study.

PubMed

Seretis, E; Konstantinidou, A; Arnogiannakis, N; Xinopoulos, D; Voloudakis-Baltatzis, I E

2010-12-01

A primary mucinous colorectal adenocarcinoma tissue with signet-ring cells, as revealed after histological evaluation, was examined ultrastructurally. The authors also analyzed the immunohistochemical data of the tissue for serotonin, vasoactive intestinal polypeptide (VIP), bombesin, somatostatin, and glucagon, using the peroxidase anti-peroxidase (PAP) method and the immunogold labeling method for light and electron microscope, respectively. Electron microscopically mucinous adenocarcinoma was characterized by the formation of small lumen. Adenocarcinoma cells were full of mucous granules of varying electron density, providing a good environment for the tumor cells to grow. They also exhibited a significant loss of microvilli and intracytoplasmic junctions, which could allow the cells to disseminate. Signet-ring cells were located in the basal site of the ducts or in the lamina propria and appeared neoplastic, with mucin accumulation intracellularly and an eccentric crescent-shaped nucleus. The cytoplasmic organelles were decreased and at the periphery of the cell. The PAP method demonstrated that these cells were strongly positive for bombesin and also positive for vasointestinal polypeptide (VIP). The immunogold method detected bombesin immunoreactivity in the vacuoles as well as in other cytoplasmic membranes, whereas VIP was localized mainly in the plasma membrane. The location of signet-ring cells combined with the immunoreactivity for bombesin and VIP indicated that signet-ring cells were of neuroendocrine origin and probably dedifferentiated enterochromaffin-like endocrine cells. These findings have implications for understanding the biological behavior of these composite malignant tumors and could help in the knowledge of the origin of signet-ring cells.

Sub-Fickean Diffusion in a One-Dimensional Plasma Ring

NASA Astrophysics Data System (ADS)

Theisen, W. L.

2013-12-01

A one-dimensional dusty plasma ring is formed in a strongly-coupled complex plasma. The dust particles in the ring can be characterized as a one-dimensional system where the particles cannot pass each other. The particles perform random walks due to thermal motions. This single-file self diffusion is characterized by the mean-squared displacement (msd) of the individual particles which increases with time t. Diffusive processes that follow Ficks law predict that the msd increases as t, however, single-file diffusion is sub-Fickean meaning that the msd is predicted to increase as t^(1/2). Particle position data from the dusty plasma ring is analyzed to determine the scaling of the msd with time. Results are compared with predictions of single-file diffusion theory.

Semiconductor ring lasers coupled by a single waveguide

NASA Astrophysics Data System (ADS)

Coomans, W.; Gelens, L.; Van der Sande, G.; Mezosi, G.; Sorel, M.; Danckaert, J.; Verschaffelt, G.

2012-06-01

We experimentally and theoretically study the characteristics of semiconductor ring lasers bidirectionally coupled by a single bus waveguide. This configuration has, e.g., been suggested for use as an optical memory and as an optical neural network motif. The main results are that the coupling can destabilize the state in which both rings lase in the same direction, and it brings to life a state with equal powers at both outputs. These are both undesirable for optical memory operation. Although the coupling between the rings is bidirectional, the destabilization occurs due to behavior similar to an optically injected laser system.

Utilizing wheel-ring architecture for stable and selectable single-longitudinal-mode erbium fiber laser

NASA Astrophysics Data System (ADS)

Yeh, Chien-Hung; Yang, Zi-Qing; Huang, Tzu-Jung; Chow, Chi-Wai

2018-03-01

To achieve a steady single-longitudinal-mode (SLM) erbium-doped fiber (EDF) laser, the wheel-ring architecture is proposed in the laser cavity. According to Vernier effect, the proposed wheel-ring can produce three different free spectrum ranges (FSRs) to serve as the mode-filter for suppressing the densely multi-longitudinal-mode (MLM). Here, to complete wavelength-tunable EDF laser, an optical tunable bandpass filter (OTBF) is utilized inside the cavity for tuning arbitrarily. In addition, the entire output performances of the proposed EDF wheel-ring laser are also discussed and analyzed experimentally.

Effects of rapid thermal annealing on the optical properties of strain-free quantum ring solar cells

PubMed Central

2013-01-01

Strain-free GaAs/Al0.33Ga0.67As quantum rings are fabricated by droplet epitaxy. Both photoresponse and photoluminescence spectra confirm optical transitions in quantum rings, suggesting that droplet epitaxial nanomaterials are applicable to intermediate band solar cells. The effects of post-growth annealing on the quantum ring solar cells are investigated, and the optical properties of the solar cells with and without thermal treatment are characterized by photoluminescence technique. Rapid thermal annealing treatment has resulted in the significant improvement of material quality, which can be served as a standard process for quantum structure solar cells grown by droplet epitaxy. PMID:23281811

Promoter scanning of the Human COX-2 gene with 8-ring polyamides: unexpected weakening of polyamide-DNA binding and selectivity by replacing an internal N-Me-pyrrole with β-alanine

PubMed Central

Aston, Karl; Ramos, Joseph P.; Koeller, Kevin J.; Nanjunda, Rupesh; He, Gaofei

2012-01-01

Rules for polyamide DNA recognition have proved invaluable for the design of sequence-selective DNA-binding agents in cell-free systems. However, these rules are not fully transferrable to predicting activity in cells, tissues or animals, and additional refinements to our understanding of DNA recognition would help biomedical studies. Similar complexities are encountered when using internal β-alanines as polyamide building blocks in place of N-methyl pyrrole; β-alanines were introduced in polyamide designs to maintain good hydrogen bonding registry with the target DNA, especially for long polyamides or those with several GC bp (P.B. Dervan, A.R. Urbach, Essays Contemp. Chem. (2001) 327–339). Thus, to clarify important subtleties of molecular recognition, we studied the effects of replacing a single pyrrole with β-alanine in 8-ring polyamides designed against the Ets-1 transcription factor. Replacement of a single internal N-methylpyrrole with β-alanine to generate a β/Im pairing in two 8-ring polyamides causes a decrease in DNA binding affinity by two orders of magnitude and decreases DNA binding selectivity, contrary to expectations based on the literature. Measurements were made by fluorescence spectroscopy, quantitative DNA footprinting and surface plasmon resonance, with these vastly different techniques showing excellent agreement. Furthermore, results were validated for a range of DNA substrates from small hairpins to long dsDNA sequences. Docking studies helped show that β-alanine does not make efficient hydrophobic contacts with the rest of the polyamide or nearby DNA, in contrast to pyrrole. These results help refine design principles and expectations for polyamide-DNA recognition. PMID:23023196

Direct interaction of FtsZ and MreB is required for septum synthesis and cell division in Escherichia coli.

PubMed

Fenton, Andrew K; Gerdes, Kenn

2013-07-03

How bacteria coordinate cell growth with division is not well understood. Bacterial cell elongation is controlled by actin-MreB while cell division is governed by tubulin-FtsZ. A ring-like structure containing FtsZ (the Z ring) at mid-cell attracts other cell division proteins to form the divisome, an essential protein assembly required for septum synthesis and cell separation. The Z ring exists at mid-cell during a major part of the cell cycle without contracting. Here, we show that MreB and FtsZ of Escherichia coli interact directly and that this interaction is required for Z ring contraction. We further show that the MreB-FtsZ interaction is required for transfer of cell-wall biosynthetic enzymes from the lateral to the mature divisome, allowing cells to synthesise the septum. Our observations show that bacterial cell division is coupled to cell elongation via a direct and essential interaction between FtsZ and MreB.

Direct interaction of FtsZ and MreB is required for septum synthesis and cell division in Escherichia coli

PubMed Central

Fenton, Andrew K; Gerdes, Kenn

2013-01-01

How bacteria coordinate cell growth with division is not well understood. Bacterial cell elongation is controlled by actin–MreB while cell division is governed by tubulin–FtsZ. A ring-like structure containing FtsZ (the Z ring) at mid-cell attracts other cell division proteins to form the divisome, an essential protein assembly required for septum synthesis and cell separation. The Z ring exists at mid-cell during a major part of the cell cycle without contracting. Here, we show that MreB and FtsZ of Escherichia coli interact directly and that this interaction is required for Z ring contraction. We further show that the MreB–FtsZ interaction is required for transfer of cell-wall biosynthetic enzymes from the lateral to the mature divisome, allowing cells to synthesise the septum. Our observations show that bacterial cell division is coupled to cell elongation via a direct and essential interaction between FtsZ and MreB. PMID:23756461

The two nerve rings of the hypostomal nervous system of Hydra vulgaris-an immunohistochemical analysis.

PubMed

Hufnagel, L A; Kass-Simon, G

2016-11-01

In Hydra vulgaris, physiological and pharmacological evidence exists for a hypostomal circumferential neuro-effector pathway that initiates ectodermal pacemaker activity at tentacular-hypostomal loci coordinating body and tentacle contractions. Here, we describe an ectodermal nerve ring that runs below and between the tentacles, and an anti-GABA B receptor antibody-labeled ring coincident with it. The location of this ring is consistent with the physiology of the hypostomal pacemaker systems of hydra. We also describe a distally located, ectodermal ring of nerve fibers that is not associated with anti-GABA B receptor antibody labeling. The neurites and cell bodies of sensory cells contribute to both rings. The location of the distal ring and its sensory cell neurites suggests an involvement in the behavior of the mouth. Between the two rings is a network of anastomosing sensory and ganglion cell bodies and their neurites. Phase contrast, darkfield, and antibody-labeled images reveal that the mouth of hydra comprises five or six epithelial folds whose endoderm extensively labels with anti-GABA B receptor antibody, suggesting that endodermal metabotrobic GABA receptors are also involved in regulating mouth behavior.

Cryo-EM structure of the gasdermin A3 membrane pore.

PubMed

Ruan, Jianbin; Xia, Shiyu; Liu, Xing; Lieberman, Judy; Wu, Hao

2018-05-01

Gasdermins mediate inflammatory cell death after cleavage by caspases or other, unknown enzymes. The cleaved N-terminal fragments bind to acidic membrane lipids to form pores, but the mechanism of pore formation remains unresolved. Here we present the cryo-electron microscopy structures of the 27-fold and 28-fold single-ring pores formed by the N-terminal fragment of mouse GSDMA3 (GSDMA3-NT) at 3.8 and 4.2 Å resolutions, and of a double-ring pore at 4.6 Å resolution. In the 27-fold pore, a 108-stranded anti-parallel β-barrel is formed by two β-hairpins from each subunit capped by a globular domain. We identify a positively charged helix that interacts with the acidic lipid cardiolipin. GSDMA3-NT undergoes radical conformational changes upon membrane insertion to form long, membrane-spanning β-strands. We also observe an unexpected additional symmetric ring of GSDMA3-NT subunits that does not insert into the membrane in the double-ring pore, which may represent a pre-pore state of GSDMA3-NT. These structures provide a basis that explains the activities of several mutant gasdermins, including defective mutants that are associated with cancer.

ZapE Is a Novel Cell Division Protein Interacting with FtsZ and Modulating the Z-Ring Dynamics

PubMed Central

Marteyn, Benoit S.; Karimova, Gouzel; Fenton, Andrew K.; Gazi, Anastasia D.; West, Nicholas; Touqui, Lhousseine; Prevost, Marie-Christine; Betton, Jean-Michel; Poyraz, Oemer; Ladant, Daniel; Gerdes, Kenn; Sansonetti, Philippe J.; Tang, Christoph M.

2014-01-01

ABSTRACT Bacterial cell division requires the formation of a mature divisome complex positioned at the midcell. The localization of the divisome complex is determined by the correct positioning, assembly, and constriction of the FtsZ ring (Z-ring). Z-ring constriction control remains poorly understood and (to some extent) controversial, probably due to the fact that this phenomenon is transient and controlled by numerous factors. Here, we characterize ZapE, a novel ATPase found in Gram-negative bacteria, which is required for growth under conditions of low oxygen, while loss of zapE results in temperature-dependent elongation of cell shape. We found that ZapE is recruited to the Z-ring during late stages of the cell division process and correlates with constriction of the Z-ring. Overexpression or inactivation of zapE leads to elongation of Escherichia coli and affects the dynamics of the Z-ring during division. In vitro, ZapE destabilizes FtsZ polymers in an ATP-dependent manner. PMID:24595368

Observation of Bright Ring Phenomenon for Red Blood Cells by Lattice Boltzmann Method

NASA Astrophysics Data System (ADS)

Kim, Young Woo; Moon, Ji Young; Lee, Joon Sang

2017-11-01

RBC (Red Blood Cell) aggregation is one of interests for various biomechanical fields such as cell chip or visualization. The unique phenomenon called ``bright ring'' is due to RBC aggregation in pulsatile flow of blood. Shear rate and flow acceleration on RBC causes them to repeat aggregating and scattering from center of the channel. The reason that this phenomenon is called bright ring is because that when observed by ultrasound imaging, the bright ring occurs periodically. Many studies tried to observe this bright ring phenomenon experimentally. However, there are yet not many studies trying to make use of this phenomenon for practical purposes. Bright ring phenomenon has high potential when used for cell separation or other microchip devices. In this paper, the Lattice Boltzmann method is used to control this bright ring phenomenon. The purpose of this paper is to find conditions when bright ring phenomenon occurs, and to control the aggregating-scattering frequency and degree. Deformability of RBC is calculated following the work of Moon JY et al. (2016). The result of this paper could be further extended to the optimization of cell-separating microchips. This work was also supported by the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (MSIP) (No. 2015R1A5A1037668) and Brain Korea 21 Plus.

Establishment of a cell model of X-linked sideroblastic anemia using genome editing.

PubMed

Kaneko, Kiriko; Kubota, Yoshiko; Nomura, Kazumi; Hayashimoto, Haruka; Chida, Taisei; Yoshino, Naoto; Wayama, Marina; Ogasawara, Katsutoshi; Nakamura, Yukio; Tooyama, Ikuo; Furuyama, Kazumichi

2018-06-13

ALAS2 gene mutations cause X-linked sideroblastic anemia. The presence of ring sideroblasts in a patient's bone marrow is the hallmark of sideroblastic anemia, but the precise mechanisms underlying sideroblast formation are largely unknown. Using a genome editing system, a mutation was introduced in the erythroid-specific enhancer of the ALAS2 gene in HUDEP2 cells, which were derived from human umbilical stem cells and can produce erythrocytes. The established cell line, termed HA2low, expressed less ALAS2 mRNA than did wild-type cells, even after erythroid differentiation. Although the mRNA expression of α-globin, β-globin, and the mitochondrial iron importer mitoferrin-1 was induced similarly in wild-type and HA2low cells, hemoglobinization of differentiated cells was limited in HA2low cells compared to wild-type cells. Importantly, Prussian blue staining revealed that approximately one-third of differentiated HA2low cells exhibited intracellular iron deposition, and these cells looked like ring sideroblasts. Electron microscopy confirmed that the mitochondria in HA2low cells contained high-density deposits that might contain iron. Ring sideroblastic cells appeared among HA2low cells only after differentiation, while the induced expression of mitochondrial ferritin was observed in both cell types during differentiation. These results suggest that the induction of mitochondrial ferritin expression might be essential for, but not the primary cause of, ring sideroblast formation. Our results also suggest that the insufficient supply of protoporphyrin IX due to ALAS2 deficiency, in combination with increased iron import into mitochondria during erythroid differentiation, results in the formation of ring sideroblasts. Furthermore, HA2low cells are a useful tool for characterizing ring sideroblasts in vitro. Copyright © 2018. Published by Elsevier Inc.

Full-wave simulation of a three-dimensional metamaterial prism

DOE PAGES

Basilio, Lorena I.; Langston, William L.; Warne, Larry K.; ...

2015-01-23

In our article, a negative-index metamaterial prism based on a composite unit cell containing a split-ring resonator and a z-dipole is designed and simulated. The design approach combines simulations of a single unit cell to identify the appropriate cell design (yielding the desired negative-index behavior) together with subcell modeling (which simplifies the mesh representation of the resonator geometry and allows for a larger number of resonator cells to be handled). Furthermore, to describe the methodology used in designing a n = -1 refractive index prism, our results include the effective-medium parameters, the far-field scattered patterns, and the near-zone field distributionsmore » corresponding to a normally incident plane-wave excitation of the prism.« less

Reconfigurable Solid-state Dye-doped Polymer Ring Resonator Lasers

NASA Astrophysics Data System (ADS)

Chandrahalim, Hengky; Fan, Xudong

2015-12-01

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3‧-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G), and 3,3‧-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm2 per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm2 per pulse was also demonstrated through the Vernier effect. The renewability of the dye-doped polymer was examined by removing and redepositing the dye-doped polymer on the same resonator hosts for multiple cycles. We recorded consistent emissions from the devices for all trials, suggesting the feasibility of employing this technology for numerous photonic and biochemical sensing applications that entail for sustainable, reconfigurable, and low lasing threshold coherent light sources on a chip.

Reconfigurable Solid-state Dye-doped Polymer Ring Resonator Lasers

PubMed Central

Chandrahalim, Hengky; Fan, Xudong

2015-01-01

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3′-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G), and 3,3′-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm2 per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm2 per pulse was also demonstrated through the Vernier effect. The renewability of the dye-doped polymer was examined by removing and redepositing the dye-doped polymer on the same resonator hosts for multiple cycles. We recorded consistent emissions from the devices for all trials, suggesting the feasibility of employing this technology for numerous photonic and biochemical sensing applications that entail for sustainable, reconfigurable, and low lasing threshold coherent light sources on a chip. PMID:26674508

Reconfigurable Solid-state Dye-doped Polymer Ring Resonator Lasers.

PubMed

Chandrahalim, Hengky; Fan, Xudong

2015-12-17

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3'-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G), and 3,3'-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm(2) per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm(2) per pulse was also demonstrated through the Vernier effect. The renewability of the dye-doped polymer was examined by removing and redepositing the dye-doped polymer on the same resonator hosts for multiple cycles. We recorded consistent emissions from the devices for all trials, suggesting the feasibility of employing this technology for numerous photonic and biochemical sensing applications that entail for sustainable, reconfigurable, and low lasing threshold coherent light sources on a chip.

A simple, single-substrate model to interpret intra-annual stable isotope signals in tree-ring cellulose

NASA Astrophysics Data System (ADS)

Ogée, J.; Barbour, M. M.; Wingate, L.; Bert, D.; Bosc, A.; Stievenard, M.; Lambrot, C.; Pierre, M.; Bariac, T.; Dewar, R. C.

2009-04-01

High-resolution intra-annual measurements of the carbon and oxygen stable isotope composition of cellulose in annual tree rings (δ13Ccellulose and δ18Ocellulose, respectively) reveal well-defined seasonal patterns that could contain valuable records of past climate and tree function. Interpreting these signals is nonetheless complex because they not only record the signature of current assimilates, but also depend on carbon allocation dynamics within the trees. Here, we present a simple, single-substrate model for wood growth containing only 12 main parameters. The model is used to interpret an isotopic intra-annual chronology collected in an even-aged maritime pine plantation growing in the South-West of France, where climate, soil and flux variables were also monitored. The empirical δ13Ccellulose and δ18Ocellulose exhibit dynamic seasonal patterns, with clear differences between years and individuals, that are mostly captured by the model. In particular, the amplitude of both signals is reproduced satisfactorily as well as the sharp 18O enrichment at the beginning of 1997 and the less pronounced 13C and 18O depletion observed at the end of the latewood. Our results suggest that the single-substrate hypothesis is a good approximation for tree ring studies on Pinus pinaster, at least for the environmental conditions covered by this study. A sensitivity analysis revealed that, in the early wood, the model was particularly sensitive to the date when cell wall thickening begins (twt). We therefore propose to use the model to reconstruct time series of twt and explore how climate influences this key parameter of xylogenesis.

Preliminary investigation of single-file diffusion in complex plasma rings

NASA Astrophysics Data System (ADS)

Theisen, W. L.; Sheridan, T. E.

2010-04-01

Particles in one-dimensional (1D) systems cannot pass each other. However, it is still possible to define a diffusion process where the mean-squared displacement (msd) of an ensemble of particles in a 1D chain increases with time t. This process is called single-file diffusion. In contrast to diffusive processes that follow Fick's law, msdt, single-file diffusion is sub-Fickean and the msd is predicted to increase as t^1/2. We have recently created 1D dusty (complex) plasma rings in the DONUT (Dusty ONU experimenT) apparatus. Particle position data from these rings will be analyzed to determine the scaling of the msd with time and results will be compared with predictions of single-file diffusion theory.

Ionization of elements in medium power capacitively coupled argon plasma torch with single and double ring electrodes.

PubMed

Ponta, Michaela; Frentiu, Maria; Frentiu, Tiberiu

2012-06-01

A medium power, low Ar consumption capacitively coupled plasma torch (275 W, 0.4 L min-1) with molybdenum tubular electrode and single or two ring electrodes in non-local thermodynamic equilibrium (LTE) was characterized with respect to its ability to achieve element ionization. Ionization degrees of Ca, Mg, Mn and Cd were determined from ionic-to-atomic emission ratio and ionization equilibrium according to Saha's equation. The ionization degrees resulted from the Saha equation were higher by 9-32% than those obtained from spectral lines intensity in LTE regime and closer to reality. A linear decrease of ionization with increase of ionization energy of elements was observed. Plasma torch with two ring electrodes provided higher ionization degrees (85 ± 7% Ca, 79 ± 7% Mn, 80 ± 7% Mg and 73 ± 8% Cd) than those in single ring arrangement (70 ± 6% Ca, 57 ± 7% Mn, 57 ± 8% Mg and 42 ± 9% Cd). The Ca ionization decreased linearly by up to 79 ± 4% and 53 ± 6% in plasma with two ring electrodes and single ring respectively in the presence of up to 400 µg mL-1 Na as interferent. The studied plasma was effective in element ionization and could be a potential ion source in mass spectrometry.

Cell-autonomous correction of ring chromosomes in human induced pluripotent stem cells

NASA Astrophysics Data System (ADS)

Bershteyn, Marina; Hayashi, Yohei; Desachy, Guillaume; Hsiao, Edward C.; Sami, Salma; Tsang, Kathryn M.; Weiss, Lauren A.; Kriegstein, Arnold R.; Yamanaka, Shinya; Wynshaw-Boris, Anthony

2014-03-01

Ring chromosomes are structural aberrations commonly associated with birth defects, mental disabilities and growth retardation. Rings form after fusion of the long and short arms of a chromosome, and are sometimes associated with large terminal deletions. Owing to the severity of these large aberrations that can affect multiple contiguous genes, no possible therapeutic strategies for ring chromosome disorders have been proposed. During cell division, ring chromosomes can exhibit unstable behaviour leading to continuous production of aneuploid progeny with low viability and high cellular death rate. The overall consequences of this chromosomal instability have been largely unexplored in experimental model systems. Here we generated human induced pluripotent stem cells (iPSCs) from patient fibroblasts containing ring chromosomes with large deletions and found that reprogrammed cells lost the abnormal chromosome and duplicated the wild-type homologue through the compensatory uniparental disomy (UPD) mechanism. The karyotypically normal iPSCs with isodisomy for the corrected chromosome outgrew co-existing aneuploid populations, enabling rapid and efficient isolation of patient-derived iPSCs devoid of the original chromosomal aberration. Our results suggest a fundamentally different function for cellular reprogramming as a means of `chromosome therapy' to reverse combined loss-of-function across many genes in cells with large-scale aberrations involving ring structures. In addition, our work provides an experimentally tractable human cellular system for studying mechanisms of chromosomal number control, which is of critical relevance to human development and disease.

Single atom array to form a Rydberg ring

NASA Astrophysics Data System (ADS)

Zhan, Mingsheng; Xu, Peng; He, Xiaodong; Liu, Min; Wang, Jin

2012-02-01

Single atom arrays are ideal quantum systems for studying few-body quantum simulation and quantum computation [1]. Towards realizing a fully controllable array we did a lot of experimental efforts, which include rotating single atoms in a ring optical lattice generated by a spatial light modulator [2], high efficient loading of two atoms into a microscopic optical trap by dynamically reshaping the trap with a spatial light modulator [3], and trapping a single atom in a blue detuned optical bottle beam trap [4]. Recently, we succeeded in trapping up to 6 atoms in a ring optical lattice with one atom in each site. Further laser cooling the array and manipulation of the inner states will provide chance to form Ryberg rings for quantum simulation. [4pt] [1] M. Saffman et al., Rev. Mod. Phys. 82, 2313 (2010)[0pt] [2] X.D. He et al., Opt. Express 17, 21014 (2009)[0pt] [3] X.D. He et al., Opt. Express 18, 13586 (2010)[0pt] [4] P. Xu et al., Opt. Lett. 35, 2164 (2010)

Signet-ring cell lymphoma of T-cell origin. An immunocytochemical and ultrastructural study relating giant vacuole formation to cytoplasmic sequestration of surface membrane.

PubMed

Grogan, T M; Richter, L C; Payne, C M; Rangel, C S

1985-09-01

In contrast to previous accounts of signet-ring lymphoma as a B-cell neoplasm, we report a case of signet-ring, large-cell lymphoma of T-cell lineage. Immunologic and ultrastructural studies were performed on a subcutaneous mass noted initially, as well as on an enlarged lymph node that developed later, in a 69-year-old man. Immunologic assessment indicated strong expression of T-helper antigen (Leu 3a + b), universal T-antigens (Leu 1, 5), and Ia. There was an absence of T-suppressor/cytotoxic antigen (Leu 2a), universal T-antigens (Leu 4, 9), and immunoglobulin light and heavy chains. Collectively, these findings indicate a mature T-cell lymphoma of T-helper type in an activated (Ia+) state. In contrast to previous reports of T-cell and Ia occurring solely as surface antigens, we demonstrated pools of cytoplasmic Leu 1, 3, 5 and Ia that displaced the nucleus. The ultrastructure of the giant cytoplasmic vacuoles was identical to the microvesicle-containing vacuoles reported in signet-ring cell lymphomas of B-cell lineage. In our case of T-cell lineage, we found substantial evidence of endocytosis by the neoplastic cells and numerous giant multivesicular bodies. The pools of cytoplasmic T and Ia antigens may result from abnormal internalization of surface T-antigens or the sequestration of T-antigen-containing Golgi-derived vesicles. Our combined immunologic and ultrastructural findings suggest that aberrant membrane recycling may be the common denominator of signet-ring formation in both B- and T-cell signet-ring lymphomas.

Fracture mechanics modeling of popping event during daughter cell separation.

PubMed

Jiang, Yuxuan; Liang, Xudong; Guo, Ming; Cao, Yanping; Cai, Shengqiang

2018-05-10

Most bacteria cells divide by binary fission which is part of a bacteria cell cycle and requires tight regulations and precise coordination. Fast separation of Staphylococcus Aureus (S. Aureus) daughter cells, named as popping event, has been observed in recent experiments. The popping event was proposed to be driven by mechanical crack propagation in the peripheral ring which connected two daughter cells before their separation. It has also been shown that after the fast separation, a small portion of the peripheral ring was left as a hinge. In the article, we develop a fracture mechanics model for the crack growth in the peripheral ring during S. Aureus daughter cell separation. In particular, using finite element analysis, we calculate the energy release rate associated with the crack growth in the peripheral ring, when daughter cells are inflated by a uniform turgor pressure inside. Our results show that with a fixed inflation of daughter cells, the energy release rate depends on the crack length non-monotonically. The energy release rate reaches a maximum value for a crack of an intermediate length. The non-monotonic relationship between the energy release rate and crack length clearly indicates that the crack propagation in the peripheral ring can be unstable. The computed energy release rate as a function of crack length can also be used to explain the existence of a small portion of peripheral ring remained as hinge after the popping event.

Nuclear envelope-distributed CD147 interacts with and inhibits the transcriptional function of RING1 and promotes melanoma cell motility.

PubMed

Chen, Junchen; Peng, Cong; Lei, Li; Zhang, Jianglin; Zeng, Weiqi; Chen, Xiang

2017-01-01

Melanoma accounts for nearly 80% of all deaths associated with skin cancer.CD147 plays a very important role in melanoma progression and the expression level may correlate with tumor malignancy. RING1 can bind DNA and act as a transcriptional repressor, play an important role in the aggressive phenotype in melanoma. The interactions between CD147 and RING1 were identified with a yeast two-hybrid and RING1 interacted with CD147 through the transmembrane domain. RING1 inhibits CD147's capability promoting melanoma cell migration. In conclusion, the study identified novel interactions between CD147 and RING1, recovered CD147 nuclear envelope distribution in melanoma cells, and suggested a new mechanism underlying how cytoplasmic CD147 promotes melanoma development.

Nuclear envelope-distributed CD147 interacts with and inhibits the transcriptional function of RING1 and promotes melanoma cell motility

PubMed Central

Peng, Cong; Lei, Li; Zhang, Jianglin; Zeng, Weiqi; Chen, Xiang

2017-01-01

Melanoma accounts for nearly 80% of all deaths associated with skin cancer.CD147 plays a very important role in melanoma progression and the expression level may correlate with tumor malignancy. RING1 can bind DNA and act as a transcriptional repressor, play an important role in the aggressive phenotype in melanoma. The interactions between CD147 and RING1 were identified with a yeast two-hybrid and RING1 interacted with CD147 through the transmembrane domain. RING1 inhibits CD147’s capability promoting melanoma cell migration. In conclusion, the study identified novel interactions between CD147 and RING1, recovered CD147 nuclear envelope distribution in melanoma cells, and suggested a new mechanism underlying how cytoplasmic CD147 promotes melanoma development. PMID:28832687

Protein Phosphatase 1ß Limits Ring Canal Constriction during Drosophila Germline Cyst Formation

PubMed Central

Yamamoto, Shinya; Bayat, Vafa; Bellen, Hugo J.; Tan, Change

2013-01-01

Germline cyst formation is essential for the propagation of many organisms including humans and flies. The cytoplasm of germline cyst cells communicate with each other directly via large intercellular bridges called ring canals. Ring canals are often derived from arrested contractile rings during incomplete cytokinesis. However how ring canal formation, maintenance and growth are regulated remains unclear. To better understand this process, we carried out an unbiased genetic screen in Drosophila melanogaster germ cells and identified multiple alleles of flapwing (flw), a conserved serine/threonine-specific protein phosphatase. Flw had previously been reported to be unnecessary for early D. melanogaster oogenesis using a hypomorphic allele. We found that loss of Flw leads to over-constricted nascent ring canals and subsequently tiny mature ring canals, through which cytoplasmic transfer from nurse cells to the oocyte is impaired, resulting in small, non-functional eggs. Flw is expressed in germ cells undergoing incomplete cytokinesis, completely colocalized with the Drosophila myosin binding subunit of myosin phosphatase (DMYPT). This colocalization, together with genetic interaction studies, suggests that Flw functions together with DMYPT to negatively regulate myosin activity during ring canal formation. The identification of two subunits of the tripartite myosin phosphatase as the first two main players required for ring canal constriction indicates that tight regulation of myosin activity is essential for germline cyst formation and reproduction in D. melanogaster and probably other species as well. PMID:23936219

Involvement of an Actomyosin Contractile Ring in Saccharomyces cerevisiae Cytokinesis

PubMed Central

Bi, Erfei; Maddox, Paul; Lew, Daniel J.; Salmon, E.D.; McMillan, John N.; Yeh, Elaine; Pringle, John R.

1998-01-01

In Saccharomyces cerevisiae, the mother cell and bud are connected by a narrow neck. The mechanism by which this neck is closed during cytokinesis has been unclear. Here we report on the role of a contractile actomyosin ring in this process. Myo1p (the only type II myosin in S. cerevisiae) forms a ring at the presumptive bud site shortly before bud emergence. Myo1p ring formation depends on the septins but not on F-actin, and preexisting Myo1p rings are stable when F-actin is depolymerized. The Myo1p ring remains in the mother–bud neck until the end of anaphase, when a ring of F-actin forms in association with it. The actomyosin ring then contracts to a point and disappears. In the absence of F-actin, the Myo1p ring does not contract. After ring contraction, cortical actin patches congregate at the mother–bud neck, and septum formation and cell separation rapidly ensue. Strains deleted for MYO1 are viable; they fail to form the actin ring but show apparently normal congregation of actin patches at the neck. Some myo1Δ strains divide nearly as efficiently as wild type; other myo1Δ strains divide less efficiently, but it is unclear whether the primary defect is in cytokinesis, septum formation, or cell separation. Even cells lacking F-actin can divide, although in this case division is considerably delayed. Thus, the contractile actomyosin ring is not essential for cytokinesis in S. cerevisiae. In its absence, cytokinesis can still be completed by a process (possibly localized cell–wall synthesis leading to septum formation) that appears to require septin function and to be facilitated by F-actin. PMID:9732290

Investigation of the characteristics of a stacked direct borohydride fuel cell for portable applications

NASA Astrophysics Data System (ADS)

Kim, Cheolhwan; Kim, Kyu-Jung; Ha, Man Yeong

To investigate the possibility of the portable application of a direct borohydride fuel cell (DBFC), weight reduction of the stack and high stacking of the cells are investigated for practical running conditions. For weight reduction, carbon graphite is adopted as the bipolar plate material even though it has disadvantages in tight stacking, which results in stacking loss from insufficient material strength. For high stacking, it is essential to have a uniform fuel distribution among cells and channels to maintain equal electric load on each cell. In particular, the design of the anode channel is important because active hydrogen generation causes non-uniformity in the fuel flow-field of the cells and channels. To reduce the disadvantages of stacking force margin and fuel maldistribution, an O-ring type-sealing system with an internal manifold and a parallel anode channel design is adopted, and the characteristics of a single and a five-cell fuel cell stack are analyzed. By adopting carbon graphite, the stack weight can be reduced by 4.2 times with 12% of performance degradation from the insufficient stacking force. When cells are stacked, the performance exceeds the single-cell performance because of the stack temperature increase from the reduction of the radiation area from the narrow stacking of cells.

Distributing coil elements in three dimensions enhances parallel transmission multiband RF performance: A simulation study in the human brain at 7 Tesla.

PubMed

Wu, Xiaoping; Tian, Jinfeng; Schmitter, Sebastian; Vaughan, J Tommy; Uğurbil, Kâmil; Van de Moortele, Pierre-François

2016-06-01

We explore the advantages of using a double-ring radiofrequency (RF) array and slice orientation to design parallel transmission (pTx) multiband (MB) pulses for simultaneous multislice (SMS) imaging with whole-brain coverage at 7 Tesla (T). A double-ring head array with 16 elements split evenly in two rings stacked in the z-direction was modeled and compared with two single-ring arrays consisting of 8 or 16 elements. The array performance was evaluated by designing band-specific pTx MB pulses with local specific absorption rate (SAR) control. The impact of slice orientations was also investigated. The double-ring array consistently and significantly outperformed the other two single-ring arrays, with peak local SAR reduced by up to 40% at a fixed excitation error of 0.024. For all three arrays, exciting sagittal or coronal slices yielded better RF performance than exciting axial or oblique slices. A double-ring RF array can be used to drastically improve SAR versus excitation fidelity tradeoff for pTx MB pulse design for brain imaging at 7 T; therefore, it is preferable against single-ring RF array designs when pursuing various biomedical applications of pTx SMS imaging. In comparing the stripline arrays, coronal and sagittal slices are more advantageous than axial and oblique slices for pTx MB pulses. Magn Reson Med 75:2464-2472, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

ParA and ParB coordinate chromosome segregation with cell elongation and division during Streptomyces sporulation

PubMed Central

Donczew, Magdalena; Mackiewicz, Paweł; Wróbel, Agnieszka; Flärdh, Klas; Zakrzewska-Czerwińska, Jolanta

2016-01-01

In unicellular bacteria, the ParA and ParB proteins segregate chromosomes and coordinate this process with cell division and chromosome replication. During sporulation of mycelial Streptomyces, ParA and ParB uniformly distribute multiple chromosomes along the filamentous sporogenic hyphal compartment, which then differentiates into a chain of unigenomic spores. However, chromosome segregation must be coordinated with cell elongation and multiple divisions. Here, we addressed the question of whether ParA and ParB are involved in the synchronization of cell-cycle processes during sporulation in Streptomyces. To answer this question, we used time-lapse microscopy, which allows the monitoring of growth and division of single sporogenic hyphae. We showed that sporogenic hyphae stop extending at the time of ParA accumulation and Z-ring formation. We demonstrated that both ParA and ParB affect the rate of hyphal extension. Additionally, we showed that ParA promotes the formation of massive nucleoprotein complexes by ParB. We also showed that FtsZ ring assembly is affected by the ParB protein and/or unsegregated DNA. Our results indicate the existence of a checkpoint between the extension and septation of sporogenic hyphae that involves the ParA and ParB proteins. PMID:27248800

Fluctuations and differential contraction during regeneration of Hydra vulgaris tissue toroids

NASA Astrophysics Data System (ADS)

Krahe, Michael; Wenzel, Iris; Lin, Kao-Nung; Fischer, Julia; Goldmann, Joseph; Kästner, Markus; Fütterer, Claus

2013-03-01

We studied regenerating bilayered tissue toroids dissected from Hydra vulgaris polyps and relate our macroscopic observations to the dynamics of force-generating mesoscopic cytoskeletal structures. Tissue fragments undergo a specific toroid-spheroid folding process leading to complete regeneration towards a new organism. The time scale of folding is too fast for biochemical signalling or morphogenetic gradients, which forced us to assume purely mechanical self-organization. The initial pattern selection dynamics was studied by embedding toroids into hydro-gels, allowing us to observe the deformation modes over longer periods of time. We found increasing mechanical fluctuations which break the toroidal symmetry, and discuss the evolution of their power spectra for various gel stiffnesses. Our observations are related to single-cell studies which explain the mechanical feasibility of the folding process. In addition, we observed switching of cells from a tissue bound to a migrating state after folding failure as well as in tissue injury. We found a supra-cellular actin ring assembled along the toroid's inner edge. Its contraction can lead to the observed folding dynamics as we could confirm by finite element simulations. This actin ring in the inner cell layer is assembled by myosin-driven length fluctuations of supra-cellular F-actin bundles (myonemes) in the outer cell layer. This paper is dedicated to Malcolm Steinberg.

Sub-nanometer pore formation in single-molecule-thick polyurea molecular-sieving membrane: a computational study.

PubMed

Park, Seongjin; Lansac, Yves; Jang, Yun Hee

2018-06-07

A polymeric network of 1-(4-tritylphenyl)urea (TPU) built via layer-by-layer cross-linking polymerization has been proposed to be an excellent mesh equipped with single-molecule-thick pores (i.e., cyclic poly-TPU rings), which can sieve glucose (∼0.7 nm) out of its mixture with urea for hemodialysis applications. Monte Carlo search for the lowest-energy conformation of various sizes of poly-TPU rings unravels the origin of narrow pore size distribution, which is around the sizes of dimer and trimer rings (0.3-0.8 nm). Flexible rings larger than the dimer and trimer rings, in particular tetramer rings, prefer a twisted conformation in the shape of the infinity symbol (∞, which looks like two dimer rings joined together) locked by a hydrogen bond between diphenylurea linker groups facing each other. Translocation energy profiles across these TPU rings reveal their urea-versus-glucose sieving mechanism: glucose is either too large (to enter dimers and twisted tetramers) or too perfectly fit (to exit trimers), leaving only a dimer-sized free space in the ring, whereas smaller-sized urea and water pass through these effective dimer-sized rings (bare dimers, twisted tetramers, and glucose-filled trimers) without encountering a substantial energy barrier or trap.

High-energy accelerator for beams of heavy ions

DOEpatents

Martin, Ronald L.; Arnold, Richard C.

1978-01-01

An apparatus for accelerating heavy ions to high energies and directing the accelerated ions at a target comprises a source of singly ionized heavy ions of an element or compound of greater than 100 atomic mass units, means for accelerating the heavy ions, a storage ring for accumulating the accelerated heavy ions and switching means for switching the heavy ions from the storage ring to strike a target substantially simultaneously from a plurality of directions. In a particular embodiment the heavy ion that is accelerated is singly ionized hydrogen iodide. After acceleration, if the beam is of molecular ions, the ions are dissociated to leave an accelerated singly ionized atomic ion in a beam. Extraction of the beam may be accomplished by stripping all the electrons from the atomic ion to switch the beam from the storage ring by bending it in magnetic field of the storage ring.

Hybrid integrated single-wavelength laser with silicon micro-ring reflector

NASA Astrophysics Data System (ADS)

Ren, Min; Pu, Jing; Krishnamurthy, Vivek; Xu, Zhengji; Lee, Chee-Wei; Li, Dongdong; Gonzaga, Leonard; Toh, Yeow T.; Tjiptoharsono, Febi; Wang, Qian

2018-02-01

A hybrid integrated single-wavelength laser with silicon micro-ring reflector is demonstrated theoretically and experimentally. It consists of a heterogeneously integrated III-V section for optical gain, an adiabatic taper for light coupling, and a silicon micro-ring reflector for both wavelength selection and light reflection. Heterogeneous integration processes for multiple III-V chips bonded to an 8-inch Si wafer have been developed, which is promising for massive production of hybrid lasers on Si. The III-V layer is introduced on top of a 220-nm thick SOI layer through low-temperature wafer-boning technology. The optical coupling efficiency of >85% between III-V and Si waveguide has been achieved. The silicon micro-ring reflector, as the key element of the hybrid laser, is studied, with its maximized reflectivity of 85.6% demonstrated experimentally. The compact single-wavelength laser enables fully monolithic integration on silicon wafer for optical communication and optical sensing application.

Stacking interactions of hydrogen-bridged rings – stronger than the stacking of benzene molecules.

PubMed

Blagojević, Jelena P; Zarić, Snežana D

2015-08-21

Analysis of crystal structures from the Cambridge Structural Database showed that 27% of all planar five-membered hydrogen-bridged rings, possessing only single bonds within the ring, form intermolecular stacking interactions. Interaction energy calculations show that interactions can be as strong as -4.9 kcal mol(-1), but dependent on ring structure.

Three-dimensional architecture of macrofibrils in the human scalp hair cortex.

PubMed

Harland, Duane P; Walls, Richard J; Vernon, James A; Dyer, Jolon M; Woods, Joy L; Bell, Fraser

2014-03-01

Human scalp hairs are comprised of a central cortex enveloped by plate-like cuticle cells. The elongate cortex cells of mature fibres are composed primarily of macrofibrils-bundles of hard-keratin intermediate filaments (IFs) chemically cross-linked within a globular protein matrix. In wool, three cell types (ortho-, meso- and paracortex) contain macrofibrils with distinctly different filament arrangements and matrix fractions, but in human hair macrofibril-cell type relationships are less clear. Here we show that hair macrofibrils all have a similar matrix fraction (∼0.4) and are typically composed of a double-twist architecture in which a central IF is surrounded by concentric rings of tangentially-angled IFs. The defining parameter is the incremental angle increase (IF-increment) between IFs of successive rings. Unlike the wool orthocortex, hair double-twist macrofibrils have considerable inter-macrofibril variation in IF increment (0.05-0.35°/nm), and macrofibril size and IF increment are negatively correlated. Correspondingly, angular difference between central and outer-most IFs is up to 40° in small macrofibrils, but only 5-10° in large macrofibrils. Single cells were observed containing mixtures of macrofibrils with different diameters. These new observations advance our understanding of the nano-level and cell-level organisation of human hair, with implications for interpretation of structure with respect the potential roles of cortex cell types in defining the mechanical properties of hair. Copyright © 2014 Elsevier Inc. All rights reserved.

Development of a microfabricated artificial limbus with micropockets for cell delivery to the cornea.

PubMed

Ortega, Ílida; Deshpande, Pallavi; Gill, Andrew A; MacNeil, Sheila; Claeyssens, Frederik

2013-06-01

The aim of this study was to develop a synthetic alternative to the human corneal limbus for use initially as an ex vivo model in which to study corneal stem cell function within a niche environment and ultimately to develop an implantable limbus for future clinical use. Microstereolithography was used for the fabrication of polyethylene glycol diacrylate (PEGDA) based rings on a macroscopic (1.2 cm) scale containing unique microfeatures (pockets) which were then modified with fibronectin to promote cell adhesion. These rings were designed to mimic the limbal area of the eye containing structures of the approximate size and shape of the stem cell microenvironments found in the palisades of Vogt. The attachment of rabbit limbal fibroblasts and rabbit limbal epithelial cells to the PEGDA rings was increased by pretreating the microfabricated structures with biotinylated fibronectin. Cell outgrowth from fibronectin coated microfabricated structures was 50% greater than from rings without structures or fibronectin coating. The cell loaded rings were then placed on an ex vivo wounded cornea model and the outgrowth of cells to form a multilayered epithelium was observed. We suggest this is a new approach to investigating limbal stem cells niches and the first steps towards a new approach for corneal regeneration.

Bub2 regulation of cytokinesis and septation in budding yeast

PubMed Central

Park, Su Young; Cable, Addie E; Blair, Jessica; Stockstill, Katherine E; Shannnon, Katie B

2009-01-01

Background The mitotic exit network (MEN) is required for events at the end of mitosis such as degradation of mitotic cyclins and cytokinesis. Bub2 and its binding partner Bfa1 act as a GTPase activating protein (GAP) to negatively regulate the MEN GTPase Tem1. The Bub2/Bfa1 checkpoint pathway is required to delay the cell cycle in response to mispositioned spindles. In addition to its role in mitotic exit, Tem1 is required for actomyosin ring contraction. Results To test the hypothesis that the Bub2 pathway prevents premature actin ring assembly, we compared the timing of actin ring formation in wild type, bub2Δ, mad2Δ, and bub2Δmad2Δ cells both with and without microtubules. There was no difference in the timing of actin ring formation between wild type and mutant cells in a synchronized cell cycle. In the presence of nocodazole, both bub2Δ and mad2Δ cells formed rings after a delay of the same duration. Double mutant bub2Δmad2Δ and bfa1Δmad2Δ cells formed rings at the same time with and without nocodazole. To determine if Bub2 has an effect on actomyosin ring contraction through its regulation of Tem1, we used live cell imaging of Myo1-GFP in a bub2Δ strain. We found a significant decrease in the total time of contraction and an increase in rate of contraction compared to wild type cells. We also examined myosin contraction using Myo1-GFP in cells overexpressing an epitope tagged Bub2. Surprisingly, overexpression of Bub2 also led to a significant increase in the rate of contraction, as well as morphological defects. The chained cell phenotype caused by Bub2 overexpression could be rescued by co-overexpression of Tem1, and was not rescued by deletion of BFA1. Conclusion Our data indicate that the Bub2 checkpoint pathway does not have a specific role in delaying actin ring formation. The observed increase in the rate of myosin contraction in the bub2Δ strain provides evidence that the MEN regulates actomyosin ring contraction. Our data suggest that the overexpression of the Bub2 fusion protein acts as a dominant negative, leading to septation defects by a mechanism that is Tem1-dependent. PMID:19490645

Bifurcation and stability of single and multiple vortex rings in three-dimensional Bose-Einstein condensates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bisset, R. N.; Wang, Wenlong; Ticknor, C.

Here, we investigate how single- and multi-vortex-ring states can emerge from a planar dark soliton in three-dimensional (3D) Bose-Einstein condensates (confined in isotropic or anisotropic traps) through bifurcations. We characterize such bifurcations quantitatively using a Galerkin-type approach and find good qualitative and quantitative agreement with our Bogoliubov–de Gennes (BdG) analysis. We also systematically characterize the BdG spectrum of the dark solitons, using perturbation theory, and obtain a quantitative match with our 3D BdG numerical calculations. We then turn our attention to the emergence of single- and multi-vortex-ring states. We systematically capture these as stationary states of the system and quantifymore » their BdG spectra numerically. We found that although the vortex ring may be unstable when bifurcating, its instabilities weaken and may even eventually disappear for sufficiently large chemical potentials and suitable trap settings. For instance, we demonstrate the stability of the vortex ring for an isotropic trap in the large-chemical-potential regime.« less

Bifurcation and stability of single and multiple vortex rings in three-dimensional Bose-Einstein condensates

DOE PAGES

Bisset, R. N.; Wang, Wenlong; Ticknor, C.; ...

2015-10-01

Here, we investigate how single- and multi-vortex-ring states can emerge from a planar dark soliton in three-dimensional (3D) Bose-Einstein condensates (confined in isotropic or anisotropic traps) through bifurcations. We characterize such bifurcations quantitatively using a Galerkin-type approach and find good qualitative and quantitative agreement with our Bogoliubov–de Gennes (BdG) analysis. We also systematically characterize the BdG spectrum of the dark solitons, using perturbation theory, and obtain a quantitative match with our 3D BdG numerical calculations. We then turn our attention to the emergence of single- and multi-vortex-ring states. We systematically capture these as stationary states of the system and quantifymore » their BdG spectra numerically. We found that although the vortex ring may be unstable when bifurcating, its instabilities weaken and may even eventually disappear for sufficiently large chemical potentials and suitable trap settings. For instance, we demonstrate the stability of the vortex ring for an isotropic trap in the large-chemical-potential regime.« less

Single-bubble and multibubble cavitation in water triggered by laser-driven focusing shock waves

NASA Astrophysics Data System (ADS)

Veysset, D.; Gutiérrez-Hernández, U.; Dresselhaus-Cooper, L.; De Colle, F.; Kooi, S.; Nelson, K. A.; Quinto-Su, P. A.; Pezeril, T.

2018-05-01

In this study a single laser pulse spatially shaped into a ring is focused into a thin water layer, creating an annular cavitation bubble and cylindrical shock waves: an outer shock that diverges away from the excitation laser ring and an inner shock that focuses towards the center. A few nanoseconds after the converging shock reaches the focus and diverges away from the center, a single bubble nucleates at the center. The inner diverging shock then reaches the surface of the annular laser-induced bubble and reflects at the boundary, initiating nucleation of a tertiary bubble cloud. In the present experiments, we have performed time-resolved imaging of shock propagation and bubble wall motion. Our experimental observations of single-bubble cavitation and collapse and appearance of ring-shaped bubble clouds are consistent with our numerical simulations that solve a one-dimensional Euler equation in cylindrical coordinates. The numerical results agree qualitatively with the experimental observations of the appearance and growth of large bubble clouds at the smallest laser excitation rings. Our technique of shock-driven bubble cavitation opens interesting perspectives for the investigation of shock-induced single-bubble or multibubble cavitation phenomena in thin liquids.

A high-throughput three-dimensional cell migration assay for toxicity screening with mobile device-based macroscopic image analysis

PubMed Central

Timm, David M.; Chen, Jianbo; Sing, David; Gage, Jacob A.; Haisler, William L.; Neeley, Shane K.; Raphael, Robert M.; Dehghani, Mehdi; Rosenblatt, Kevin P.; Killian, T. C.; Tseng, Hubert; Souza, Glauco R.

2013-01-01

There is a growing demand for in vitro assays for toxicity screening in three-dimensional (3D) environments. In this study, 3D cell culture using magnetic levitation was used to create an assay in which cells were patterned into 3D rings that close over time. The rate of closure was determined from time-lapse images taken with a mobile device and related to drug concentration. Rings of human embryonic kidney cells (HEK293) and tracheal smooth muscle cells (SMCs) were tested with ibuprofen and sodium dodecyl sulfate (SDS). Ring closure correlated with the viability and migration of cells in two dimensions (2D). Images taken using a mobile device were similar in analysis to images taken with a microscope. Ring closure may serve as a promising label-free and quantitative assay for high-throughput in vivo toxicity in 3D cultures. PMID:24141454

Fiber Laser Development for LISA

NASA Technical Reports Server (NTRS)

Numata, Kenji; Chen, Jeffrey R.

2009-01-01

We have developed a linearly-polarized Ytterbium-doped fiber ring laser with single longitudinal-mode output at 1064nm for LISA and other space applications. Single longitudinal-mode selection was achieved by using a fiber Bragg grating (FBG) and a fiber Fabry-Perot (FFP). The FFP also serves as a frequency-reference within our ring laser. Our laser exhibits comparable low frequency and intensity noise to Non-Planar Ring Oscillator (NPRO). By using a fiber-coupled phase modulator as a frequency actuator, the laser frequency can be electro-optically tuned at a rate of 100kHz. It appears that our fiber ring laser is promising for space applications where robustness of fiber optics is desirable.

The midbody ring scaffolds the abscission machinery in the absence of midbody microtubules

PubMed Central

Green, Rebecca A.; Mayers, Jonathan R.; Wang, Shaohe; Lewellyn, Lindsay; Desai, Arshad; Audhya, Anjon

2013-01-01

Abscission completes cytokinesis to form the two daughter cells. Although abscission could be organized from the inside out by the microtubule-based midbody or from the outside in by the contractile ring–derived midbody ring, it is assumed that midbody microtubules scaffold the abscission machinery. In this paper, we assess the contribution of midbody microtubules versus the midbody ring in the Caenorhabditis elegans embryo. We show that abscission occurs in two stages. First, the cytoplasm in the daughter cells becomes isolated, coincident with formation of the intercellular bridge; proper progression through this stage required the septins (a midbody ring component) but not the membrane-remodeling endosomal sorting complex required for transport (ESCRT) machinery. Second, the midbody and midbody ring are released into a specific daughter cell during the subsequent cell division; this stage required the septins and the ESCRT machinery. Surprisingly, midbody microtubules were dispensable for both stages. These results delineate distinct steps during abscission and highlight the central role of the midbody ring, rather than midbody microtubules, in their execution. PMID:24217623

The Chloroplast Division Protein ARC6 Acts to Inhibit Disassembly of GDP-bound FtsZ2.

PubMed

Sung, Min Woo; Shaik, Rahamthulla; TerBush, Allan D; Osteryoung, Katherine W; Vitha, Stanislav; Holzenburg, Andreas

2018-05-16

Chloroplasts host photosynthesis and fulfill other metabolic functions that are essential to plant life. They have to divide by binary fission to maintain their numbers throughout cycles of cell division. Chloroplast division is achieved by a complex ring-shaped division machinery located on both the inner (stromal) and the outer (cytosolic) side of the chloroplast envelope. The inner division ring (termed the Z ring) is formed by the assembly of tubulin-like FtsZ1 and FtsZ2 proteins. ARC6 is a key chloroplast division protein that interacts with the Z ring. ARC6 spans the inner envelope membrane, is known to stabilize or maintain the Z ring, and anchors the Z ring to the inner membrane through interaction with FtsZ2. The underlying mechanism of Z-ring stabilization is not well understood. Here, biochemical and structural characterization of ARC6 was conducted using light scattering, sedimentation, and light and transmission electron microscopy. The recombinant protein was purified as a dimer. The results indicated that a truncated form of ARC6 (tARC6), representing the stromal portion of ARC6, affects FtsZ2 assembly without forming higher-order structures, and exerts its effect via FtsZ2 dynamics. tARC6 prevented GDP-induced FtsZ2 disassembly and caused a significant net increase in FtsZ2 assembly when GDP was present. Single particle analysis and 3D reconstruction were performed to elucidate the structural basis of ARC6 activity. Together, the data reveal that a dimeric form of tARC6 binds to FtsZ2 filaments and does not increase FtsZ polymerization rates but rather inhibits GDP-associated FtsZ2 disassembly. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

Unprecedented zeolite-like framework topology constructed from cages with 3-rings in a barium oxonitridophosphate.

PubMed

Sedlmaier, Stefan J; Döblinger, Markus; Oeckler, Oliver; Weber, Johannes; auf der Günne, Jörn Schmedt; Schnick, Wolfgang

2011-08-10

A novel oxonitridophosphate, Ba(19)P(36)O(6+x)N(66-x)Cl(8+x) (x ≈ 4.54), has been synthesized by heating a multicomponent reactant mixture consisting of phosphoryl triamide OP(NH(2))(3), thiophosphoryl triamide SP(NH(2))(3), BaS, and NH(4)Cl enclosed in an evacuated and sealed silica glass ampule up to 750 °C. Despite the presence of side phases, the crystal structure was elucidated ab initio from high-resolution synchrotron powder diffraction data (λ = 39.998 pm) applying the charge flipping algorithm supported by independent symmetry information derived from electron diffraction (ED) and scanning transmission electron microscopy (STEM). The compound crystallizes in the cubic space group Fm ̅3c (no. 226) with a = 2685.41(3) pm and Z = 8. As confirmed by Rietveld refinement, the structure comprises all-side vertex sharing P(O,N)(4) tetrahedra forming slightly distorted 3(8)4(6)8(12) cages representing a novel composite building unit (CBU). Interlinked through their 4-rings and additional 3-rings, the cages build up a 3D network with a framework density FD = 14.87 T/1000 Å(3) and a 3D 8-ring channel system. Ba(2+) and Cl(-) as extra-framework ions are located within the cages and channels of the framework. The structural model is corroborated by (31)P double-quantum (DQ) /single-quantum (SQ) and triple-quantum (TQ) /single-quantum (SQ) 2D correlation MAS NMR spectroscopy. According to (31)P{(1)H} C-REDOR NMR measurements, the H content is less than one H atom per unit cell. © 2011 American Chemical Society

Gastric marginal zone lymphoma of mucosa-associated lymphoid tissue and signet ring cell carcinoma, synchronous collision tumour of the stomach: a case report.

PubMed

George, Smiley Annie; Junaid, T A

2014-01-01

To report a rare case of synchronous marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) signet ring cell carcinoma occurring as a collision tumour in the stomach. A 53-year-old man was diagnosed initially with signet ring cell carcinoma of the stomach. The microscopy of the subsequent total gastrectomy revealed a collision tumour of MALT lymphoma and signet ring cell carcinoma associated with Helicobacter pylori gastritis. This case highlighted the importance of a careful evaluation of the accompanying lymphoid population in the biopsy samples of gastric adenocarcinoma and underlined the need for multiple endoscopic biopsies to detect these rare synchronous tumours. © 2013 S. Karger AG, Basel.

Gastric Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue and Signet Ring Cell Carcinoma, Synchronous Collision Tumour of the Stomach: A Case Report

PubMed Central

George, Smiley Annie; Junaid, T.A.

2014-01-01

Objective To report a rare case of synchronous marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) signet ring cell carcinoma occurring as a collision tumour in the stomach. Clinical Presentation and Intervention A 53-year-old man was diagnosed initially with signet ring cell carcinoma of the stomach. The microscopy of the subsequent total gastrectomy revealed a collision tumour of MALT lymphoma and signet ring cell carcinoma associated with Helicobacter pylori gastritis. Conclusion This case highlighted the importance of a careful evaluation of the accompanying lymphoid population in the biopsy samples of gastric adenocarcinoma and underlined the need for multiple endoscopic biopsies to detect these rare synchronous tumours. PMID:24247357

Inflammasome activation causes dual recruitment of NLRC4 and NLRP3 to the same macromolecular complex.

PubMed

Man, Si Ming; Hopkins, Lee J; Nugent, Eileen; Cox, Susan; Glück, Ivo M; Tourlomousis, Panagiotis; Wright, John A; Cicuta, Pietro; Monie, Tom P; Bryant, Clare E

2014-05-20

Pathogen recognition by nucleotide-binding oligomerization domain-like receptor (NLR) results in the formation of a macromolecular protein complex (inflammasome) that drives protective inflammatory responses in the host. It is thought that the number of inflammasome complexes forming in a cell is determined by the number of NLRs being activated, with each NLR initiating its own inflammasome assembly independent of one another; however, we show here that the important foodborne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) simultaneously activates at least two NLRs, whereas only a single inflammasome complex is formed in a macrophage. Both nucleotide-binding domain and leucine-rich repeat caspase recruitment domain 4 and nucleotide-binding domain and leucine-rich repeat pyrin domain 3 are simultaneously present in the same inflammasome, where both NLRs are required to drive IL-1β processing within the Salmonella-infected cell and to regulate the bacterial burden in mice. Superresolution imaging of Salmonella-infected macrophages revealed a macromolecular complex with an outer ring of apoptosis-associated speck-like protein containing a caspase activation and recruitment domain and an inner ring of NLRs, with active caspase effectors containing the pro-IL-1β substrate localized internal to the ring structure. Our data reveal the spatial localization of different components of the inflammasome and how different members of the NLR family cooperate to drive robust IL-1β processing during Salmonella infection.

Nine unanswered questions about cytokinesis

PubMed Central

2017-01-01

Experiments on model systems have revealed that cytokinesis in cells with contractile rings (amoebas, fungi, and animals) depends on shared molecular mechanisms in spite of some differences that emerged during a billion years of divergent evolution. Understanding these fundamental mechanisms depends on identifying the participating proteins and characterizing the mechanisms that position the furrow, assemble the contractile ring, anchor the ring to the plasma membrane, trigger ring constriction, produce force to form a furrow, disassemble the ring, expand the plasma membrane in the furrow, and separate the daughter cell membranes. This review reveals that fascinating questions remain about each step. PMID:28807993

Nine unanswered questions about cytokinesis.

PubMed

Pollard, Thomas D

2017-10-02

Experiments on model systems have revealed that cytokinesis in cells with contractile rings (amoebas, fungi, and animals) depends on shared molecular mechanisms in spite of some differences that emerged during a billion years of divergent evolution. Understanding these fundamental mechanisms depends on identifying the participating proteins and characterizing the mechanisms that position the furrow, assemble the contractile ring, anchor the ring to the plasma membrane, trigger ring constriction, produce force to form a furrow, disassemble the ring, expand the plasma membrane in the furrow, and separate the daughter cell membranes. This review reveals that fascinating questions remain about each step. © 2017 Pollard.

Single-molecule conductance through multiple π-π-stacked benzene rings determined with direct electrode-to-benzene ring connections.

PubMed

Schneebeli, Severin T; Kamenetska, Maria; Cheng, Zhanling; Skouta, Rachid; Friesner, Richard A; Venkataraman, Latha; Breslow, Ronald

2011-02-23

Understanding electron transport across π-π-stacked systems will help to answer fundamental questions about biochemical redox processes and benefit the design of new materials and molecular devices. Herein we employed the STM break-junction technique to measure the single-molecule conductance of multiple π-π-stacked aromatic rings. We studied electron transport through up to four stacked benzene rings held together in an eclipsed fashion via a paracyclophane scaffold. We found that the strained hydrocarbons studied herein couple directly to gold electrodes during the measurements; hence, we did not require any heteroatom binding groups as electrical contacts. Density functional theory-based calculations suggest that the gold atoms of the electrodes bind to two neighboring carbon atoms of the outermost cyclophane benzene rings in η(2) fashion. Our measurements show an exponential decay of the conductance with an increasing number of stacked benzene rings, indicating a nonresonant tunneling mechanism. Furthermore, STM tip-substrate displacement data provide additional evidence that the electrodes bind to the outermost benzene rings of the π-π-stacked molecular wires.

Application of quantum-dot multi-wavelength lasers and silicon photonic ring resonators to data-center optical interconnects

NASA Astrophysics Data System (ADS)

Beckett, Douglas J. S.; Hickey, Ryan; Logan, Dylan F.; Knights, Andrew P.; Chen, Rong; Cao, Bin; Wheeldon, Jeffery F.

2018-02-01

Quantum dot comb sources integrated with silicon photonic ring-resonator filters and modulators enable the realization of optical sub-components and modules for both inter- and intra-data-center applications. Low-noise, multi-wavelength, single-chip, laser sources, PAM4 modulation and direct detection allow a practical, scalable, architecture for applications beyond 400 Gb/s. Multi-wavelength, single-chip light sources are essential for reducing power dissipation, space and cost, while silicon photonic ring resonators offer high-performance with space and power efficiency.

Single and multiple vortex rings in three-dimensional Bose-Einstein condensates: Existence, stability, and dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wenlong; Bisset, R. N.; Ticknor, Christopher

In the present work, we explore the existence, stability, and dynamics of single- and multiple-vortex-ring states that can arise in Bose-Einstein condensates. Earlier works have illustrated the bifurcation of such states in the vicinity of the linear limit for isotropic or anisotropic three-dimensional harmonic traps. Here, we extend these states to the regime of large chemical potentials, the so-called Thomas-Fermi limit, and explore their properties such as equilibrium radii and inter-ring distance for multi-ring states, as well as their vibrational spectra and possible instabilities. In this limit, both the existence and stability characteristics can be partially traced to a particlemore » picture that considers the rings as individual particles oscillating within the trap and interacting pairwise with one another. In conclusion, we examine some representative instability scenarios of the multi-ring dynamics, including breakup and reconnections, as well as the transient formation of vortex lines.« less

Tunable filters based on an SOI nano-wire waveguide micro ring resonator

NASA Astrophysics Data System (ADS)

Shuai, Li; Yuanda, Wu; Xiaojie, Yin; Junming, An; Jianguang, Li; Hongjie, Wang; Xiongwei, Hu

2011-08-01

Micro ring resonator (MRR) filters based on a silicon on insulator (SOI) nanowire waveguide are fabricated by electron beam photolithography (EBL) and inductive coupled plasma (ICP) etching technology. The cross-section size of the strip waveguides is 450 × 220 nm2, and the bending radius of the micro ring is around 5 μm. The test results from the tunable filter based on a single ring show that the free spectral range (FSR) is 16.8 nm and the extinction ratio (ER) around the wavelength 1550 nm is 18.1 dB. After thermal tuning, the filter's tuning bandwidth reaches 4.8 nm with a tuning efficiency of 0.12 nm/°C Meanwhile, we fabricated and studied multi-channel filters based on a single ring and a double ring. After measurement, we drew the following conclusions: during the signal transmission of multi-channel filters, crosstalk exists mainly among different transmission channels and are fairly distinct when there are signals input to add ports.

Single and multiple vortex rings in three-dimensional Bose-Einstein condensates: Existence, stability, and dynamics

DOE PAGES

Wang, Wenlong; Bisset, R. N.; Ticknor, Christopher; ...

2017-04-27

In the present work, we explore the existence, stability, and dynamics of single- and multiple-vortex-ring states that can arise in Bose-Einstein condensates. Earlier works have illustrated the bifurcation of such states in the vicinity of the linear limit for isotropic or anisotropic three-dimensional harmonic traps. Here, we extend these states to the regime of large chemical potentials, the so-called Thomas-Fermi limit, and explore their properties such as equilibrium radii and inter-ring distance for multi-ring states, as well as their vibrational spectra and possible instabilities. In this limit, both the existence and stability characteristics can be partially traced to a particlemore » picture that considers the rings as individual particles oscillating within the trap and interacting pairwise with one another. In conclusion, we examine some representative instability scenarios of the multi-ring dynamics, including breakup and reconnections, as well as the transient formation of vortex lines.« less

Single scan femtosecond laser transverse writing of depressed cladding waveguides enabled by three-dimensional focal field engineering.

PubMed

Zhang, Qian; Yang, Dong; Qi, Jia; Cheng, Ya; Gong, Qihuang; Li, Yan

2017-06-12

We report single scan transverse writing of depressed cladding waveguides inside ZBLAN glass with the longitudinally oriented annular ring-shaped focal intensity distribution of the femtosecond laser. The entire region of depressed cladding at the cross section, where a negative change of refraction index is induced, can be modified simultaneously with the ring-shaped focal intensity profile. The fabricated waveguides exhibit good single guided mode.

Assembly of the MreB-associated cytoskeletal ring of Escherichia coli.

PubMed

Vats, Purva; Shih, Yu-Ling; Rothfield, Lawrence

2009-04-01

The Escherichia coli actin homologue MreB is part of a helical cytoskeletal structure that winds around the cell between the two poles. It has been shown that MreB redistributes during the cell cycle to form circumferential ring structures that flank the cytokinetic FtsZ ring and appear to be associated with division and segregation of the helical cytoskeleton. We show here that the MreB cytoskeletal ring also contains the MreC, MreD, Pbp2 and RodA proteins. Assembly of MreB, MreC, MreD and Pbp2 into the ring structure required the FtsZ ring but no other known components of the cell division machinery, whereas assembly of RodA into the cytoskeletal ring required one or more additional septasomal components. Strikingly, MreB, MreC, MreD and RodA were each able to independently assemble into the cytoskeletal ring and coiled cytoskeletal structures in the absence of any of the other ring components. This excludes the possibility that one or more of these proteins acts as a scaffold for incorporation of the other proteins into these structures. In contrast, incorporation of Pbp2 required the presence of MreC, which may provide a docking site for Pbp2 entry.

Tunable Er-doped fiber ring laser with single longitudinal mode operation based on Rayleigh backscattering in single mode fiber.

PubMed

Yin, Guolu; Saxena, Bhavaye; Bao, Xiaoyi

2011-12-19

A tunable and single longitudinal mode Er-doped fiber ring laser (SLM-EDFRL) is proposed and demonstrated based on Rayleigh backscattering (RBS) in single mode fiber-28e (SMF-28e). Theory and experimental study on formation of SLM from normal multi-mode ring laser is demonstrated. The RBS feedback in 660 m SMF-28e is the key to ensure SLM laser oscillation. This tunable SLM laser can be tuned over 1549.7-1550.18 nm with a linewidth of 2.5-3.0 kHz and a side mode suppression ratio (SMSR) of ~72 dB for electrical signal power. The tuning range is determined by the bandpass filter and gain medium used in the experiment. The laser is able to operate at S+C+L band.

RING-Domain E3 Ligase-Mediated Host–Virus Interactions: Orchestrating Immune Responses by the Host and Antagonizing Immune Defense by Viruses

PubMed Central

Zhang, Yuexiu; Li, Lian-Feng; Munir, Muhammad; Qiu, Hua-Ji

2018-01-01

The RING-domain E3 ligases (RING E3s), a group of E3 ligases containing one or two RING finger domains, are involved in various cellular processes such as cell proliferation, immune regulation, apoptosis, among others. In the host, a substantial number of the RING E3s have been implicated to inhibit viral replication through regulating immune responses, including activation and inhibition of retinoic acid-inducible gene I-like receptors, toll-like receptors, and DNA receptor signaling pathways, modulation of cell-surface expression of major histocompatibility complex, and co-stimulatory molecules. During the course of evolution and adaptation, viruses encode RING E3s to antagonize host immune defense, such as the infected cell protein 0 of herpes simplex virus type 1, the non-structural protein 1 of rotavirus, and the K3 and K5 of Kaposi’s sarcoma-associated herpesvirus. In addition, recent studies suggest that viruses can hijack the host RING E3s to facilitate viral replication. Based on emerging and interesting discoveries, the RING E3s present novel links among the host and viruses. Herein, we focus on the latest research progresses in the RING E3s-mediated host–virus interactions and discuss the outlooks of the RING E3s for future research. PMID:29872431

Influence of C-H···O Hydrogen Bonds on Macroscopic Properties of Supramolecular Assembly.

PubMed

Ji, Wei; Liu, Guofeng; Li, Zijian; Feng, Chuanliang

2016-03-02

For CH···O hydrogen bonds in assembled structures and the applications, one of the critical issues is how molecular spatial structures affect their interaction modes as well as how to translate the different modes into the macroscopic properties of materials. Herein, coumarin-derived isomeric hydrogelators with different spatial structures are synthesized, where only nitrogen atoms locate at the ortho, meso, or para position in the pyridine ring. The gelators can self-assemble into single crystals and nanofibrous networks through CH···O interactions, which are greatly influenced by nitrogen spatial positions in the pyridine ring, leading to the different self-assembly mechanisms, packing modes, and properties of the nanofibrous networks. Typically, different cell proliferation rates are obtained on the different CH···O bonds driving nanofibrous structures, implying that tiny variation of the stereo-position of nitrogen atoms can be sensitively detected by cells. The study paves a novel way to investigate the influence of isomeric molecular assembly on macroscopic properties and functions of materials.

Evaluating the diffusion coefficient of dopamine at the cell surface during amperometric detection: disk vs ring microelectrodes.

PubMed

Trouillon, Raphaël; Lin, Yuqing; Mellander, Lisa J; Keighron, Jacqueline D; Ewing, Andrew G

2013-07-02

During exocytosis, small quantities of neurotransmitters are released by the cell. These neurotransmitters can be detected quantitatively using electrochemical methods, principally with disk carbon fiber microelectrode amperometry. An exocytotic event then results in the recording of a current peak whose characteristic features are directly related to the mechanisms of exocytosis. We have compared two exocytotic peak populations obtained from PC12 cells with a disk carbon fiber microelectrode and with a pyrolyzed carbon ring microelectrode array, with a 500 nm ring thickness. The specific shape of the ring electrode allows for precise analysis of diffusion processes at the vicinity of the cell membrane. Peaks obtained with a ring microelectrode array show a distorted average shape, owing to increased diffusion pathways. This result has been used to evaluate the diffusion coefficient of dopamine at the surface of a cell, which is up to an order of magnitude smaller than that measured in free buffer. The lower rate of diffusion is discussed as resulting from interactions with the glycocalyx.

An integrated microfluidic cell for detection, manipulation, and sorting of single micron-sized magnetic beads

NASA Astrophysics Data System (ADS)

Jiang, Z.; Llandro, J.; Mitrelias, T.; Bland, J. A. C.

2006-04-01

A lab-on-a-chip integrated microfluidic cell has been developed for magnetic biosensing, which is comprised of anisotropic magnetoresistance (AMR) sensors optimized for the detection of single magnetic beads and electrodes to manipulate and sort the beads, integrated into a microfluidic channel. The device is designed to read out the real-time signal from 9 μm diameter magnetic beads moving over AMR sensors patterned into 18×4.5 μm rectangles and 10 μm diameter rings and arranged in Wheatstone bridges. The beads are moved over the sensors along a 75×75 μm wide channel patterned in SU8. Beads of different magnetic moments can be sorted through a magnetostatic sorting gate into different branches of the microfluidic channel using a magnetic field gradient applied by lithographically defined 120 nm thick Cu striplines carrying 0.2 A current.

Three dimensional metafilms with dual channel unit cells

DOE PAGES

Burckel, D. Bruce; Campione, Salvatore; Davids, Paul S.; ...

2017-04-04

Three-dimensional (3D) metafilms composed of periodic arrays of silicon unit cells containing single and multiple micrometer-scale vertical split ring resonators (SRRs) per unit cell were fabricated. In contrast to planar and stacked planar structures, these 3D metafilms have a thickness t ~λ d/4, allowing for classical thin film effects in the long wavelength limit. The infrared specular far-field scattering response was measured for metafilms containing one and two resonators per unit cell and compared to numerical simulations. Excellent agreement in the frequency region below the onset of diffractive scattering was obtained. For dense arrays of unit cells containing single SRRs,more » normally incident linearly polarized plane waves which do not excite a resonant response result in thin film interference fringes in the reflected spectra and are virtually indistinguishable from the scattering response of an undecorated array of unit cells. For the resonant linear polarization, the specular reflection for arrays is highly dependent on the SRR orientation on the vertical face for gap-up, gap-down, and gap-right orientations. For dense arrays of unit cells containing two SRRs per unit cell positioned on adjacent faces, the specular reflection spectra are slightly modified due to near-field coupling between the orthogonally oriented SRRs but otherwise exhibit reflection spectra largely representative of the corresponding single-SRR unit cell structures. Lastly, the ability to pack the unit cell with multiple inclusions which can be independently excited by choice of incident polarization suggests the construction of dual-channel films where the scattering response is selected by altering the incident polarization.« less

Distinct 15q Genotypes in Russell-Silver and Ring 15 Syndromes

PubMed Central

Rogan, Peter K.; Seip, James R.; Driscoll, Daniel J.; Papenhausen, Peter R.; Johnson, Virginia P.; Raskin, Salmo; Woodward, Amy L.; Butler, Merlin G.

2018-01-01

Individuals with a ring 15 chromosome [r(15)] and those with Russell-Silver syndrome have short stature, developmental delay, triangular face, and clinodactyly. To assess whether the apparent phenotypic overlap of these conditions reflects a common genetic cause, the extent of deletions in chromosome 15q was determined in 5 patients with r(15), 1 patient with del 15q26.1–qter, and 5 patients with Russell- Silver syndrome. All patients with Russell- Silver syndrome were diploid for genetic markers in distal 15q, indicating that Russell-Silver syndrome in these individuals was unlikely to be related to the expression of single alleles at these or linked genetic loci. At least 3 distinct sites of chromosome breakage close to the telomere were found in the r(15) and del 15q25.1–qter patients, with 1 r(15) patient having both a terminal and an interstitial deletion. Although the patient with del 15q25.1–qter exhibited the largest deletion and the most profound growth retardation, the degree of growth impairment among the r(15) patients was not correlated with the size of the deleted interval. Rather, the parental origin of the ring chromosome in several patients was associated with phenotypes that are also seen in patients with either Prader-Willi (PWS) or Angelman (AS) syndromes, conditions that result from uniparental expression of genes on chromosome 15. In fact, unequal representation of chromosome 15 alleles in 1 patient with r(15) suggests the possibility that a mosaic karyotype composed of the constitutional cell line and cell line(s) possibly deficient in the ring chromosome might be present. The PWS-like or AS-like phenotypes could be explained by postzygotic loss of the ring chromosome, leading to uniparental inheritance of the intact chromosome in some tissues of r(15) patients. PMID:8779316

CYK-4 regulates Rac, but not Rho, during cytokinesis

PubMed Central

Zhuravlev, Yelena; Hirsch, Sophia M.; Jordan, Shawn N.; Dumont, Julien; Shirasu-Hiza, Mimi; Canman, Julie C.

2017-01-01

Cytokinesis is driven by constriction of an actomyosin contractile ring that is controlled by Rho-family small GTPases. Rho, activated by the guanine-nucleotide exchange factor ECT-2, is upstream of both myosin-II activation and diaphanous formin-mediated filamentous actin (f-actin) assembly, which drive ring constriction. The role for Rac and its regulators is more controversial, but, based on the finding that Rac inactivation can rescue cytokinesis failure when the GTPase-activating protein (GAP) CYK-4 is disrupted, Rac activity was proposed to be inhibitory to contractile ring constriction and thus specifically inactivated by CYK-4 at the division plane. An alternative model proposes that Rac inactivation generally rescues cytokinesis failure by reducing cortical tension, thus making it easier for the cell to divide when ring constriction is compromised. In this alternative model, CYK-4 was instead proposed to activate Rho by binding ECT-2. Using a combination of time-lapse in vivo single-cell analysis and Caenorhabditis elegans genetics, our evidence does not support this alternative model. First, we found that Rac disruption does not generally rescue cytokinesis failure: inhibition of Rac specifically rescues cytokinesis failure due to disruption of CYK-4 or ECT-2 but does not rescue cytokinesis failure due to disruption of two other contractile ring components, the Rho effectors diaphanous formin and myosin-II. Second, if CYK-4 regulates cytokinesis through Rho rather than Rac, then CYK-4 inhibition should decrease levels of downstream targets of Rho. Inconsistent with this, we found no change in the levels of f-actin or myosin-II at the division plane when CYK-4 GAP activity was reduced, suggesting that CYK-4 is not upstream of ECT-2/Rho activation. Instead, we found that the rescue of cytokinesis in CYK-4 mutants by Rac inactivation was Cdc42 dependent. Together our data suggest that CYK-4 GAP activity opposes Rac (and perhaps Cdc42) during cytokinesis. PMID:28298491

Infants' use of category knowledge and object attributes when segregating objects at 8.5 months of age.

PubMed

Needham, Amy; Cantlon, Jessica F; Ormsbee Holley, Susan M

2006-12-01

The current research investigates infants' perception of a novel object from a category that is familiar to young infants: key rings. We ask whether experiences obtained outside the lab would allow young infants to parse the visible portions of a partly occluded key ring display into one single unit, presumably as a result of having categorized it as a key ring. This categorization was marked by infants' perception of the keys and ring as a single unit that should move together, despite their attribute differences. We showed infants a novel key ring display in which the keys and ring moved together as one rigid unit (Move-together event) or the ring moved but the keys remained stationary throughout the event (Move-apart event). Our results showed that 8.5-month-old infants perceived the keys and ring as connected despite their attribute differences, and that their perception of object unity was eliminated as the distinctive attributes of the key ring were removed. When all of the distinctive attributes of the key ring were removed, the 8.5-month-old infants perceived the display as two separate units, which is how younger infants (7-month-old) perceived the key ring display with all its distinctive attributes unaltered. These results suggest that on the basis of extensive experience with an object category, infants come to identify novel members of that category and expect them to possess the attributes typical of that category.

Laser-diode-pumped 1319-nm monolithic non-planar ring single-frequency laser

NASA Astrophysics Data System (ADS)

Wang, Qing; Gao, Chunqing; Zhao, Yan; Yang, Suhui; Wei, Guanghui; 2, Dongmei Hong

2003-10-01

Single-frequency 1319-nm laser was obtained by using a laser-diode-pumped monolithic Nd:YAG crystal with a non-planar ring oscillator (NPRO). When the NPRO laser was pumped by an 800-?m fiber coupled laser diode, the output power of the single-frequency 1319-nm laser was 220 mW, and the slope efficiency was 16%. With a 100-1m fiber coupled diode laser pumped, 99-mW single-frequency 1319-nm laser was obtained with a slope efficiency of 29%.

3D Printing of Thermo-Responsive Methylcellulose Hydrogels for Cell-Sheet Engineering.

PubMed

Cochis, Andrea; Bonetti, Lorenzo; Sorrentino, Rita; Contessi Negrini, Nicola; Grassi, Federico; Leigheb, Massimiliano; Rimondini, Lia; Farè, Silvia

2018-04-10

A possible strategy in regenerative medicine is cell-sheet engineering (CSE), i.e., developing smart cell culture surfaces from which to obtain intact cell sheets (CS). The main goal of this study was to develop 3D printing via extrusion-based bioprinting of methylcellulose (MC)-based hydrogels. Hydrogels were prepared by mixing MC powder in saline solutions (Na₂SO₄ and PBS). MC-based hydrogels were analyzed to investigate the rheological behavior and thus optimize the printing process parameters. Cells were tested in vitro on ring-shaped printed hydrogels; bulk MC hydrogels were used for comparison. In vitro tests used murine embryonic fibroblasts (NIH/3T3) and endothelial murine cells (MS1), and the resulting cell sheets were characterized analyzing cell viability and immunofluorescence. In terms of CS preparation, 3D printing proved to be an optimal approach to obtain ring-shaped CS. Cell orientation was observed for the ring-shaped CS and was confirmed by the degree of circularity of their nuclei: cell nuclei in ring-shaped CS were more elongated than those in sheets detached from bulk hydrogels. The 3D printing process appears adequate for the preparation of cell sheets of different shapes for the regeneration of complex tissues.

Expanding Actin Rings Zipper the Mouse Embryo for Blastocyst Formation.

PubMed

Zenker, Jennifer; White, Melanie D; Gasnier, Maxime; Alvarez, Yanina D; Lim, Hui Yi Grace; Bissiere, Stephanie; Biro, Maté; Plachta, Nicolas

2018-04-19

Transformation from morula to blastocyst is a defining event of preimplantation embryo development. During this transition, the embryo must establish a paracellular permeability barrier to enable expansion of the blastocyst cavity. Here, using live imaging of mouse embryos, we reveal an actin-zippering mechanism driving this embryo sealing. Preceding blastocyst stage, a cortical F-actin ring assembles at the apical pole of the embryo's outer cells. The ring structure forms when cortical actin flows encounter a network of polar microtubules that exclude F-actin. Unlike stereotypical actin rings, the actin rings of the mouse embryo are not contractile, but instead, they expand to the cell-cell junctions. Here, they couple to the junctions by recruiting and stabilizing adherens and tight junction components. Coupling of the actin rings triggers localized myosin II accumulation, and it initiates a tension-dependent zippering mechanism along the junctions that is required to seal the embryo for blastocyst formation. Copyright © 2018 Elsevier Inc. All rights reserved.

The Distracting Effects of a Ringing Cell Phone: An Investigation of the Laboratory and the Classroom Setting

PubMed Central

Shelton, Jill T.; Elliott, Emily M.; Lynn, Sharon D.; Exner, Amanda L.

2010-01-01

The detrimental effects of a ringing phone on cognitive performance were investigated in four experiments. In Experiments 1 and 2, the effects of different types of sounds (a standard cell phone ring, irrelevant tones and an instrumental song commonly encountered by participants) on performance were examined. In Experiment 1, slower responses were observed in all auditory groups relative to a silence condition, but participants in the ring and song conditions recovered more slowly. In Experiment 2, participants who were warned about the potential for distraction recovered more quickly, suggesting a benefit of this prior knowledge. This investigation continued in a college classroom setting (Experiments 3a and 3b); students were exposed to a ringing cell phone during the lecture. Performance on a surprise quiz revealed low accuracy rates on material presented while the phone was ringing. These findings offer insight into top-down cognitive processes that moderate involuntary orienting responses associated with a common stimulus encountered in the environment. PMID:21234286

Bi-directional transmission of molecular information by photon or electron beams passing in the close vicinity of specific molecules, and its clinical and basic research applications: 1) Diagnosis of humans or animal patients without any direct contact; 2) Light microscopic and electron microscopic localization of neuro-transmitters, heavy metals, Oncogen C-fos (AB2), etc. of intracellular fine structures of normal and abnormal single cells using light or electro-microscopic indirect Bi-Digital O-Ring Test.

PubMed

Omura, Y; Losco, M; Omura, A K; Takeshige, C; Hisamitsu, T; Nakajima, H; Soejima, K; Yamamoto, S; Ishikawa, H; Kagoshima, T

1992-01-01

In 1985, Omura, Y. discovered that, when specific molecules were placed anywhere in the close vicinity of the path of a light beam (laser), their molecular information, as well as information on electrical & magnetic fields, is transmitted bi-directionally along the path of this light beam. Namely, this information is transmitted in the direction the light beam is projected and towards the direction from which the light beam is coming. This finding was applied to the following clinical and basic research: 1) In the past, using indirect Bi-Digital O-Ring Test, human or animal patients were diagnosed through an intermediate third person holding a good electrical conducting probe, the tip of which was touching the part of the patient to be examined. However, in order to diagnose the patient in isolation from a distance, or a dangerous or unmanagable unanesthesized animal, such as a lion or tiger, the author succeeded in making a diagnosis by replacing the metal conducting probe with a soft laser beam which is held by the one hand of the third person whose index finger is placed in close vicinity of the laser beam generated by a battery-powered penlight-type solid state laser generator. Thus, diagnosis within visible distance, without direct patient contact, became a reality. 2) Using a projection light microscope, by giving indirect Bi-Digital O-Ring Test while contacting with a fine electro-conductive probe on the magnified fine structure of normal and abnormal cells, various normal and abnormal intracellular substances were localized through a third person holding a pure reference control substance with the same hand that is holding the probe as an intermediary for the indirect Bi-Digital O-Ring Test. Instead of the photon beam in a light microscope, the author found that, using an electron beam passing through the close vicinity of specific molecules of specimens in an electron microscope, the molecular information is transmitted to the magnified fluorescent screen, and an indirect Bi-Digital O-Ring Test could be performed through a projected penlight-type solid state soft laser beam on the magnified intracellular structure through an observation glass window. Using the magnified fine structure of the cells, by either a light projection microscopic field or electron microscope, in various cancer cells of both humans and animals, Oncogen C-fos (AB2) and mercury were found inside of the nucleus. Integrin alpha 5 beta 1 was found on cell membranes and nuclear cell membranes of cancer cells. Acetylcholine was not found anywhere within cancer cells.(ABSTRACT TRUNCATED AT 400 WORDS)

The non-planar single-frequency ring laser with variable output coupling

NASA Astrophysics Data System (ADS)

Wu, Ke-ying; Yang, Su-hui; Wei, Guang-hui

2002-03-01

We put forward a novel non-planar single-frequency ring laser, which consists of a corner cube prism and a specially cut Porro prism made by Nd:YAG crystal. The relative angle between the corner cube and the Porro prism could be adjusted to control the output coupling of the laser resonator and the polarization-state of the output laser. A 1.06 μm single-frequency laser with 1 W output has been obtained.

5.7  W cw single-frequency laser at 671  nm by single-pass second harmonic generation of a 17.2  W injection-locked 1342  nm Nd : YVO4 ring laser using periodically poled MgO : LiNbO3.

PubMed

Koch, Peter; Ruebel, Felix; Bartschke, Juergen; L'huillier, Johannes A

2015-11-20

We demonstrate a continuous wave single-frequency laser at 671.1 nm based on a high-power 888 nm pumped Nd:YVO4 ring laser at 1342.2 nm. Unidirectional operation of the fundamental ring laser is achieved with the injection-locking technique. A Nd:YVO4 microchip laser serves as the injecting seed source, providing a tunable single-frequency power of up to 40 mW. The ring laser emits a single-frequency power of 17.2 W with a Gaussian beam profile and a beam propagation factor of M2<1.1. A 60-mm-long periodically poled MgO-doped LiNbO3 crystal is used to generate the second harmonic in a single-pass scheme. Up to 5.7 W at 671.1 nm with a Gaussian shaped beam profile and a beam propagation factor of M2<1.2 are obtained, which is approximately twice the power of previously reported lasers. This work opens possibilities in cold atoms experiments with lithium, allowing the use of larger ensembles in magneto-optical traps or higher diffraction orders in atomic beam interferometers.

Single-frequency Nd:YAG ring lasers with corner cube prism

NASA Astrophysics Data System (ADS)

Wu, Ke Ying; Yang, Su Hui; Zhao, Chang Ming; Wei, Guang Hui

2000-04-01

Kane and Byer reported the first monolithic non-planar miniature ring lasers in 1985. An intrinsic optical diode enforces unidirectional and hence single-frequency oscillation of this device. It has the advantages of compactness, reliability and high efficiency. We put forward another form of the non-planar ring lasers, in which the corner cube prism is the key element and the Nd:YAG crystal is used as a Porro prism to enclose the ring resonator. The phase shift due to the total internal reflections of the three differently orientated reflection planes of the corner cube prism, Faraday rotation in the Nd:YAG crystal placed in a magnetic field and the different output coupling in S and P polarization form an optical diode and enforce the single- frequency generating. A round trip analysis of the polarization properties of the resonator is made by the evaluation of Jones matrix. The results of our initial experiment are given in the paper.

NASA Tech Briefs, June 2007

NASA Technical Reports Server (NTRS)

2007-01-01

Topics covered include: High-Accuracy, High-Dynamic-Range Phase-Measurement System; Simple, Compact, Safe Impact Tester; Multi-Antenna Radar Systems for Doppler Rain Measurements; 600-GHz Electronically Tunable Vector Measurement System; Modular Architecture for the Measurement of Space Radiation; VLSI Design of a Turbo Decoder; Architecture of an Autonomous Radio Receiver; Improved On-Chip Measurement of Delay in an FPGA or ASIC; Resource Selection and Ranking; Accident/Mishap Investigation System; Simplified Identification of mRNA or DNA in Whole Cells; Printed Multi-Turn Loop Antennas for RF Biotelemetry; Making Ternary Quantum Dots From Single-Source Precursors; Improved Single-Source Precursors for Solar-Cell Absorbers; Spray CVD for Making Solar-Cell Absorber Layers; Glass/BNNT Composite for Sealing Solid Oxide Fuel Cells; A Method of Assembling Compact Coherent Fiber-Optic Bundles; Manufacturing Diamond Under Very High Pressure; Ring-Resonator/Sol-Gel Interferometric Immunosensor; Compact Fuel-Cell System Would Consume Neat Methanol; Algorithm Would Enable Robots to Solve Problems Creatively; Hypothetical Scenario Generator for Fault-Tolerant Diagnosis; Smart Data Node in the Sky; Pseudo-Waypoint Guidance for Proximity Spacecraft Maneuvers; Update on Controlling Herds of Cooperative Robots; and Simulation and Testing of Maneuvering of a Planetary Rover.

Selection of lasing direction in single mode semiconductor square ring cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jin-Woong; Kim, Kyoung-Youm; Moon, Hee-Jong

We propose and demonstrate a selection scheme of lasing direction by imposing a loss imbalance structure into the single mode square ring cavity. The control of the traveling direction is realized by introducing a taper-step section in one of the straight waveguides of the square ring cavity. It was shown by semi-analytic calculation that the taper-step section in the cavity provides effective loss imbalance between two travelling directions as the round trip repeats. Various kinds of square cavities were fabricated using InGaAsP/InGaAs multiple quantum well semiconductor materials in order to test the direction selectivity while maintaining the single mode. Wemore » also measured the pump power dependent lasing spectra to investigate the maintenance property of the lasing direction. The experimental results demonstrated that the proposed scheme is an efficient means for a unidirectional lasing in a single mode laser.« less

Ring Attractor Dynamics Emerge from a Spiking Model of the Entire Protocerebral Bridge.

PubMed

Kakaria, Kyobi S; de Bivort, Benjamin L

2017-01-01

Animal navigation is accomplished by a combination of landmark-following and dead reckoning based on estimates of self motion. Both of these approaches require the encoding of heading information, which can be represented as an allocentric or egocentric azimuthal angle. Recently, Ca 2+ correlates of landmark position and heading direction, in egocentric coordinates, were observed in the ellipsoid body (EB), a ring-shaped processing unit in the fly central complex (CX; Seelig and Jayaraman, 2015). These correlates displayed key dynamics of so-called ring attractors, namely: (1) responsiveness to the position of external stimuli; (2) persistence in the absence of external stimuli; (3) locking onto a single external stimulus when presented with two competitors; (4) stochastically switching between competitors with low probability; and (5) sliding or jumping between positions when an external stimulus moves. We hypothesized that ring attractor-like activity in the EB arises from reciprocal neuronal connections to a related structure, the protocerebral bridge (PB). Using recent light-microscopy resolution catalogs of neuronal cell types in the PB (Lin et al., 2013; Wolff et al., 2015), we determined a connectivity matrix for the PB-EB circuit. When activity in this network was simulated using a leaky-integrate-and-fire model, we observed patterns of activity that closely resemble the reported Ca 2+ phenomena. All qualitative ring attractor behaviors were recapitulated in our model, allowing us to predict failure modes of the putative PB-EB ring attractor and the circuit dynamics phenotypes of thermogenetic or optogenetic manipulations. Ring attractor dynamics emerged under a wide variety of parameter configurations, even including non-spiking leaky-integrator implementations. This suggests that the ring-attractor computation is a robust output of this circuit, apparently arising from its high-level network properties (topological configuration, local excitation and long-range inhibition) rather than fine-scale biological detail.

SELF CALIBRATED STMR ARRAY FOR MATERIAL CHARACTERIZATION AND SHM OF ORTHOTROPIC PLATE-LIKE STRUCTURES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vishnuvardhan, J.; Muralidharan, Ajith; Balasubramaniam, Krishnan

A full ring STMR array patch had been used for Structural Health Monitoring (SHM) of anisotropic materials where the elastic moduli, correspond to the virgin sample, were used in the calculations. In the present work an in-situ SHM has been successfully demonstrated using a novel compact sensor patch (Double ring single quadrant small footprint STMR array) through simultaneous reconstruction of the elastic moduli, material symmetry, orientation of principal planes and defect imaging. The direct received signals were used to measure Lamb wave velocities, which were used in a slowness based reconstructed algorithm using Genetic Algorithm to reconstruct the elastic moduli,more » material symmetry and orientation of principal planes. The measured signals along with the reconstructed elastic moduli were used in the phased addition algorithm for imaging the damages present on the structure. To show the applicability of the method, simulations were carried out with the double ring single quadrant STMR array configuration to image defects and are compared with the images obtained using simulation data of the full ring STMR array configuration. The experimental validation has been carried out using 3.15 mm quasi-isotropic graphite-epoxy composite. The double ring single quadrant STMR array has advantages over the full ring STMR array as it can carry out in-situ SHM with limited footprint on the structure.« less

Enhancement of the Power-Conversion Efficiency of Organic Solar Cells via Unveiling an Appropriate Rational Design Strategy in Indacenodithiophene- alt-quinoxaline π-Conjugated Polymers.

PubMed

Chochos, Christos L; Singh, Ranbir; Gregoriou, Vasilis G; Kim, Min; Katsouras, Athanasios; Serpetzoglou, Efthymis; Konidakis, Ioannis; Stratakis, Emmanuel; Cho, Kilwon; Avgeropoulos, Apostolos

2018-03-28

We report on the photovoltaic parameters, photophysical properties, optoelectronic properties, self-assembly, and morphology variations in a series of high-performance donor-acceptor (D-A) π-conjugated polymers based on indacenodithiophene and quinoxaline moieties as a function of the number-average molecular weight ([Formula: see text]), the nature of aryl substituents, and the enlargement of the polymer backbone. One of the most important outcome is that from the three optimization approaches followed to tune the chemical structure toward enhanced photovoltaic performance in bulk heterojunction solar cell devices with the fullerene derivative [6,6]-phenyl-C 71 -butyric acid methyl ester as the electron acceptor, the choice of the aryl substituent is the most efficient rational design strategy. Incorporation of thienyl rings as substituents versus phenyl rings accelerates the electron-hole extraction process to the respective electrode, despite the slightly lower recombination lifetime and, thus, improves the electrical performance of the device. Single-junction solar cells based on ThIDT-TQxT feature a maximum power-conversion efficiency of 7.26%. This study provides significant insights toward understanding of the structure-properties-performance relationship for D-A π-conjugated polymers in solid state, which provide helpful inputs for the design of next-generation polymeric semiconductors for organic solar cells with enhanced performance.

Signet-ring cell carcinoma in gastric biopsies: expecting the unexpected.

PubMed

Golembeski, Christopher P; Genta, Robert Maximilian

2013-02-01

This study was designed to establish the relative prevalence of intestinal-type and signet-ring carcinoma in gastric biopsy specimens from ambulatory patients, to determine the percentage of signet-ring carcinomas that could be expected based on the available clinical and endoscopic information, and to estimate the likelihood of missing a tumour. We extracted data of all patients with a diagnosis of primary gastric carcinoma from a national pathology database. We then reviewed clinical information and original slides, classified tumours as intestinal or signet-ring-type, and categorised the latter as 'unexpected' (no alarming symptoms, no mention of suspicious lesions) or 'expected' (clinical or endoscopic information suggestive of tumour). Unexpected signet-ring carcinomas were categorised as 'obvious' or 'challenging' (rare signet-ring cells; immunohistochemical stains used to confirm the nature of the infiltrates). There were 310 109 patients with gastric biopsies; 615 patients had primary gastric carcinoma (359 intestinal and 256 signet-ring-type). Gastric cancer was more common in men (OR 2.54; 95% CI 2.05 to 3.14; p<.0001) for intestinal-type and (OR 1.90; 95% CI 1.48 to 2.42; p<0.0001) for signet-ring cell type). Intestinal-type carcinoma occurred in older patients than signet-ring-type (median age 74 vs 65 years, p<0.001). There were 196 expected and 60 unexpected signet-ring carcinomas; 47 of the 60 unexpected cases were histopathologically obvious. Thus, only 13 signet-ring carcinomas (1 in 25 000 gastric biopsy sets) were truly unexpected. Signet-ring carcinoma is a rare finding in gastric biopsy specimens from ambulatory patients; routine due diligence and the clinical/endoscopic information provided are usually adequate to raise pathologists' index of suspicion.

Thermoelectric effect in Aharonov-Bohm structures.

PubMed

Lu, Xin; Wang, Jian-Sheng; Morrel, William G; Ni, Xiaoxi; Wu, Chang-Qin; Li, Baowen

2015-01-28

The thermoelectric effects of a single Aharonov-Bohm (SAB) ring and coupled double Aharonov-Bohm (DAB) rings have been investigated on a theoretical basis, taking into account the contributions of both electrons and phonons to the transport process by using the nonequilibrium Green's function technique. The thermoelectric figure of merit of the coupled DAB rings cannot be predicted directly by combining the values of two SAB ring systems due to the contribution of electron-phonon interaction to coupling between the two sites connecting the rings. We find that thermoelectric efficiency can be optimized by modulating the phases of the magnetic flux threading the two rings.

Micro-Ring Structures Stabilize Microdroplets to Enable Long Term Spheroid Culture in 384 Hanging Drop Array Plates

PubMed Central

Hsiao, Amy Y.; Tung, Yi-Chung; Kuo, Chuan-Hsien; Mosadegh, Bobak; Bedenis, Rachel; Pienta, Kenneth J.; Takayama, Shuichi

2012-01-01

Using stereolithography, 20 different structural variations comprised of millimeter diameter holes surrounded by trenches, plateaus, or micro-ring structures were prepared and tested for their ability to stably hold arrays of microliter sized droplets within the structures over an extended period of time. The micro-ring structures were the most effective in stabilizing droplets against mechanical and chemical perturbations. After confirming the importance of micro-ring structures using rapid prototyping, we developed an injection molding tool for mass production of polystyrene 3D cell culture plates with an array of 384 such micro-ring surrounded through-hole structures. These newly designed and injection molded polystyrene 384 hanging drop array plates with micro-rings were stable and robust against mechanical perturbations as well as surface fouling-facilitated droplet spreading making them capable of long term cell spheroid culture of up to 22 days within the droplet array. This is a significant improvement over previously reported 384 hanging drop array plates which are susceptible to small mechanical shocks and could not reliably maintain hanging drops for longer than a few days. With enhanced droplet stability, the hanging drop array plates with micro-ring structures provide better platforms and open up new opportunities for high-throughput preparation of microscale 3D cell constructs for drug screening and cell analysis. PMID:22057945

Micro-ring structures stabilize microdroplets to enable long term spheroid culture in 384 hanging drop array plates.

PubMed

Hsiao, Amy Y; Tung, Yi-Chung; Kuo, Chuan-Hsien; Mosadegh, Bobak; Bedenis, Rachel; Pienta, Kenneth J; Takayama, Shuichi

2012-04-01

Using stereolithography, 20 different structural variations comprised of millimeter diameter holes surrounded by trenches, plateaus, or micro-ring structures were prepared and tested for their ability to stably hold arrays of microliter sized droplets within the structures over an extended period of time. The micro-ring structures were the most effective in stabilizing droplets against mechanical and chemical perturbations. After confirming the importance of micro-ring structures using rapid prototyping, we developed an injection molding tool for mass production of polystyrene 3D cell culture plates with an array of 384 such micro-ring surrounded through-hole structures. These newly designed and injection molded polystyrene 384 hanging drop array plates with micro-rings were stable and robust against mechanical perturbations as well as surface fouling-facilitated droplet spreading making them capable of long term cell spheroid culture of up to 22 days within the droplet array. This is a significant improvement over previously reported 384 hanging drop array plates which are susceptible to small mechanical shocks and could not reliably maintain hanging drops for longer than a few days. With enhanced droplet stability, the hanging drop array plates with micro-ring structures provide better platforms and open up new opportunities for high-throughput preparation of microscale 3D cell constructs for drug screening and cell analysis.

Reconstitution of Contractile FtsZ Rings in Liposomes

PubMed Central

Osawa, Masaki; Anderson, David E.; Erickson, Harold P.

2009-01-01

FtsZ is a tubulin homolog and the major cytoskeletal protein in bacterial cell division. It assembles into the Z ring, which contains FtsZ and a dozen other division proteins, and constricts to divide the cell. We have constructed a membrane-targeted FtsZ (FtsZ-mts) by splicing an amphipathic helix to its C terminus. When mixed with lipid vesicles, FtsZ-mts was incorporated into the interior of some tubular vesicles. There it formed multiple Z rings that could move laterally in both directions along the length of the liposome and coalesce into brighter Z rings. Brighter Z rings produced visible constrictions in the liposome, suggesting that FtsZ itself can assemble the Z ring and generate a force. No other proteins were needed for assembly and force generation. PMID:18420899

Androgynous, Reconfigurable Closed Loop Feedback Controlled Low Impact Docking System With Load Sensing Electromagnetic Capture Ring

NASA Technical Reports Server (NTRS)

Lewis, James L. (Inventor); Carroll, Monty B. (Inventor); Morales, Ray H. (Inventor); Le, Thang D. (Inventor)

2002-01-01

The present invention relates to a fully androgynous, reconfigurable closed loop feedback controlled low impact docking system with load sensing electromagnetic capture ring. The docking system of the present invention preferably comprises two Docking- assemblies, each docking assembly comprising a load sensing ring having an outer face, one of more electromagnets, one or more load cells coupled to said load sensing ring. The docking assembly further comprises a plurality of actuator arms coupled to said load sensing ring and capable of dynamically adjusting the orientation of said load sensing ring and a reconfigurable closed loop control system capable of analyzing signals originating from said plurality of load cells and of outputting real time control for each of the actuators. The docking assembly of the present invention incorporates an active load sensing system to automatically dynamically adjust the load sensing ring during capture instead of requiring significant force to push and realign the ring.

Composite correlation filter for O-ring detection in stationary colored noise

NASA Astrophysics Data System (ADS)

Hassebrook, Laurence G.

2009-04-01

O-rings are regularly replaced in aircraft and if they are not replaced or if they are installed improperly, they can result in catastrophic failure of the aircraft. It is critical that the o-rings be packaged correctly to avoid mistakes made by technicians during routine maintenance. For this reason, fines may be imposed on the o-ring manufacturer if the o-rings are packaged incorrectly. That is, a single o-ring must be packaged and labeled properly. No o-rings or more than one o-ring per package is not acceptable. We present an industrial inspection system based on real-time composite correlation filtering that has successfully solved this problem in spite of opaque paper o-ring packages. We present the system design including the composite filter design.

Tunable electromagnetically induced transparency in coupled three-dimensional split-ring-resonator metamaterials

PubMed Central

Han, Song; Cong, Longqing; Lin, Hai; Xiao, Boxun; Yang, Helin; Singh, Ranjan

2016-01-01

Metamaterials have recently enabled coupling induced transparency due to interference effects in coupled subwavelength resonators. In this work, we present a three dimensional (3-D) metamaterial design with six-fold rotational symmetry that shows electromagnetically induced transparency with a strong polarization dependence to the incident electromagnetic wave due to the ultra-sharp resonance line width as a result of interaction between the constituent meta-atoms. However, when the six-fold rotationally symmetric unit cell design was re-arranged into a fourfold rotational symmetry, we observed the excitation of a polarization insensitive dual-band transparency. Thus, the 3-D split-ring resonators allow new schemes to observe single and multi-band classical analogues of electromagnetically induced transparencies that has huge potential applications in slowing down light, sensing modalities, and filtering functionalities either in the passive mode or the active mode where such effects could be tuned by integrating materials with dynamic properties. PMID:26857034

Inter-ring rotations of AAA ATPase p97 revealed by electron cryomicroscopy

PubMed Central

Yeung, Heidi O.; Förster, Andreas; Bebeacua, Cecilia; Niwa, Hajime; Ewens, Caroline; McKeown, Ciarán; Zhang, Xiaodong; Freemont, Paul S.

2014-01-01

The type II AAA+ protein p97 is involved in numerous cellular activities, including endoplasmic reticulum-associated degradation, transcription activation, membrane fusion and cell-cycle control. These activities are at least in part regulated by the ubiquitin system, in which p97 is thought to target ubiquitylated protein substrates within macromolecular complexes and assist in their extraction or disassembly. Although ATPase activity is essential for p97 function, little is known about how ATP binding or hydrolysis is coupled with p97 conformational changes and substrate remodelling. Here, we have used single-particle electron cryomicroscopy (cryo-EM) to study the effect of nucleotides on p97 conformation. We have identified conformational heterogeneity within the cryo-EM datasets from which we have resolved two major p97 conformations. A comparison of conformations reveals inter-ring rotations upon nucleotide binding and hydrolysis that may be linked to the remodelling of target protein complexes. PMID:24598262

Miniaturized dual-band antenna array with double-negative (DNG) metamaterial for wireless applications

NASA Astrophysics Data System (ADS)

Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Rahim, Sharul Kamal Abdul; Vandenbosch, Guy A. E.; Narbudowicz, Adam

2017-01-01

A miniaturized dual-band antenna array using a negative index metamaterial is presented for WiMAX, LTE, and WLAN applications. This left-handed metamaterial plane is located behind the antenna array, and its unit cell is a combination of split-ring resonator, square electric ring resonator, and rectangular electrical coupled resonator. This enables the achievement of a metamaterial structure exhibiting both negative permittivity and permeability, which results in antenna size miniaturization, efficiency, and gain enhancement. Moreover, the proposed metamaterial antenna has realized dual-band operating frequencies compared to a single frequency for normal antenna. The measured reflection coefficient (S11) shows a 50.25% bandwidth in the lower band (from 2.119 to 3.058 GHz) and 4.27% in the upper band (from 5.058 to 5.276 GHz). Radiation efficiency obtained in the lower and upper band are >95 and 80%, respectively.

Quantitative tracking of tumor cells in phase-contrast microscopy exploiting halo artifact pattern

NASA Astrophysics Data System (ADS)

Kang, Mi-Sun; Song, Soo-Min; Lee, Hana; Kim, Myoung-Hee

2012-03-01

Tumor cell morphology is closely related to its invasiveness characteristics and migratory behaviors. An invasive tumor cell has a highly irregular shape, whereas a spherical cell is non-metastatic. Thus, quantitative analysis of cell features is crucial to determine tumor malignancy or to test the efficacy of anticancer treatment. We use phase-contrast microscopy to analyze single cell morphology and to monitor its change because it enables observation of long-term activity of living cells without photobleaching and phototoxicity, which is common in other fluorescence-labeled microscopy. Despite this advantage, there are image-level drawbacks to phase-contrast microscopy, such as local light effect and contrast interference ring, among others. Thus, we first applied a local filter to compensate for non-uniform illumination. Then, we used intensity distribution information to detect the cell boundary. In phase-contrast microscopy images, the cell normally appears as a dark region surrounded by a bright halo. As the halo artifact around the cell body is minimal and has an asymmetric diffusion pattern, we calculated the cross-sectional plane that intersected the center of each cell and was orthogonal to the first principal axis. Then, we extracted the dark cell region by level set. However, a dense population of cultured cells still rendered single-cell analysis difficult. Finally, we measured roundness and size to classify tumor cells into malignant and benign groups. We validated segmentation accuracy by comparing our findings with manually obtained results.

3D Printing of Thermo-Responsive Methylcellulose Hydrogels for Cell-Sheet Engineering

PubMed Central

Cochis, Andrea; Sorrentino, Rita; Grassi, Federico; Leigheb, Massimiliano; Farè, Silvia

2018-01-01

A possible strategy in regenerative medicine is cell-sheet engineering (CSE), i.e., developing smart cell culture surfaces from which to obtain intact cell sheets (CS). The main goal of this study was to develop 3D printing via extrusion-based bioprinting of methylcellulose (MC)-based hydrogels. Hydrogels were prepared by mixing MC powder in saline solutions (Na2SO4 and PBS). MC-based hydrogels were analyzed to investigate the rheological behavior and thus optimize the printing process parameters. Cells were tested in vitro on ring-shaped printed hydrogels; bulk MC hydrogels were used for comparison. In vitro tests used murine embryonic fibroblasts (NIH/3T3) and endothelial murine cells (MS1), and the resulting cell sheets were characterized analyzing cell viability and immunofluorescence. In terms of CS preparation, 3D printing proved to be an optimal approach to obtain ring-shaped CS. Cell orientation was observed for the ring-shaped CS and was confirmed by the degree of circularity of their nuclei: cell nuclei in ring-shaped CS were more elongated than those in sheets detached from bulk hydrogels. The 3D printing process appears adequate for the preparation of cell sheets of different shapes for the regeneration of complex tissues. PMID:29642573

Metastatic signet-ring cell cancer of the bladder responding to chemotherapy with capecitabine: case report and review of literature

PubMed Central

Michels, Jorg; Barbour, Sean; Cavers, Douglas; Chi, Kim N.

2010-01-01

Signet-ring cell cancers deriving from the bladder are rare entities and usually present with advanced incurable disease and associated poor outlook. No standard effective chemotherapeutic option has been described largely due to the rarity of this malignancy. We report a case of a patient with metastatic bladder cancer, signet-ring cell variant. The patient progressed rapidly on standard first-line bladder cancer chemotherapy with gemcitabine and carboplatin. He responded well to second-line capecitabine with a clinically meaningful progression-free survival. PMID:20368884

Periodic growth of bacterial colonies

NASA Astrophysics Data System (ADS)

Yamazaki, Yoshihiro; Ikeda, Takemasa; Shimada, Hirotoshi; Hiramatsu, Fumiko; Kobayashi, Naoki; Wakita, Jun-ichi; Itoh, Hiroto; Kurosu, Sayuri; Nakatsuchi, Michio; Matsuyama, Tohey; Matsushita, Mitsugu

2005-06-01

The formation of concentric ring colonies by bacterial species Bacillus subtilis and Proteus mirabilis has been investigated experimentally, focusing our attention on the dependence of local cell density upon the bacterial motility. It has been confirmed that these concentric ring colonies reflect the periodic change of the bacterial motility between motile cell state and immotile cell state. We conclude that this periodic change is macroscopically determined neither by biological factors (i.e., biological clock) nor by chemical factors (chemotaxis as inhibitor). And our experimental results strongly suggest that the essential factor for the change of the bacterial motility during concentric ring formation is the local cell density.

A rare single cytogenetic finding of isochromosome 14q in a female with refractory anemia with ring sideroblasts (RARS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haag, M.M.; Sutcliffe, M.J.; Nelson, R.P.

1994-09-01

Clonal cytogenetic abnormalities occur in 79% of patients with myelodysplastic syndrome (MDS) and can be used to diagnose malignancy. Some of these clonal chromosomal changes have been useful in evaluation of the pathobiological similarity between MDS and acute nonlymphocytic leukemia (ANLL) and can be used to monitor the disease progression. A 44-year-old woman, presenting with normochromic, normocytic anemia was clinically asymptomatic and physical examination revealed no lymphadenopathy or hepatosplenomegaly. Stains for iron demonstrated adequate stores but with numerours ring sideroblasts which constituted approximately 15% of the total erythoblastic population. No increased reticulum or fibrosis was noted. These findings supported amore » diagnosis of MDS, classification refractory anemia with ring sideroblasts (RARS). Bone marrow cytogentic analysis showed an isochromosome 14q as the sole chromosome abnormality and this was confirmed by molecular cytogenetics using a whole chromosome Coatasome probe for No. 14. A population of 46,XX cells (20%) was also observed. Numerous interphase cells had three isolated fluorescent signals for No. 14. Structural and numerical abnormalities of chromosome No. 14 are reported in many hematological disorders, but few structural abnormalities have been reported for RARS and no extra copies, including i(14q), have been reported for MD or RARS. However, examples of extra copies of No. 14, including the isochromosome form, have been reported for ANLL. Since 15% of RARS patients progress to ANLL, there may be prognostic significance to this chromosome abnormality for his patient. The patient is awaiting a suitable donor for bone marrow transplantation. The presence of isochromosome No. 14 in the malignant cells offers an opportunity to monitor disease progression pre-transplantation and minimal residual disease post-transplantation.« less

Morphological evolution of Ge/Si(001) quantum dot rings formed at the rim of wet-etched pits.

PubMed

Grydlik, Martyna; Brehm, Moritz; Schäffler, Friedrich

2012-10-30

We demonstrate the formation of Ge quantum dots in ring-like arrangements around predefined {111}-faceted pits in the Si(001) substrate. We report on the complex morphological evolution of the single quantum dots contributing to the rings by means of atomic force microscopy and demonstrate that by careful adjustment of the epitaxial growth parameters, such rings containing densely squeezed islands can be grown with large spatial distances of up to 5 μm without additional nucleation of randomly distributed quantum dots between the rings.

Assembly Mechanism of the Contractile Ring for Cytokinesis by Fission Yeast

NASA Astrophysics Data System (ADS)

Vavylonis, Dimitrios; Wu, Jian-Qiu; Huang, Xiaolei; O'Shaughnessy, Ben; Pollard, Thomas

2008-03-01

Animals and fungi assemble a contractile ring of actin filaments and the motor protein myosin to separate into individual daughter cells during cytokinesis. We studied the mechanism of contractile ring assembly in fission yeast with high time resolution confocal microscopy, computational image analysis methods, and numerical simulations. Approximately 63 nodes containing myosin, broadly distributed around the cell equator, assembled into a ring through stochastic motions, making many starts, stops, and changes of direction as they condense into a ring. Estimates of node friction coefficients from the mean square displacement of stationary nodes imply forces for node movement are greater than ˜ 4 pN, similarly to forces by a few molecular motors. Skeletonization and topology analysis of images of cells expressing fluorescent actin filament markers showed transient linear elements extending in all directions from myosin nodes and establishing connections among them. We propose a model with traction between nodes depending on transient connections established by stochastic search and capture (``search, capture, pull and release''). Numerical simulations of the model using parameter values obtained from experiment succesfully condense nodes into a continuous ring.

Bridging the divide

PubMed Central

McLean, Peter F; Cooley, Lynn

2014-01-01

Ring canals are made from arrested cleavage furrows, and provide direct cytoplasmic connections among sibling cells. They are well documented for their participation in Drosophila oogenesis, but little is known about their role in several somatic tissues in which they are also found. Using a variety of genetic tools in live and fixed tissue, we recently demonstrated that rapid intercellular exchange occurs through somatic ring canals by diffusion, and presented evidence that ring canals permit equilibration of protein among transcriptionally mosaic cells. We also used a novel combination of markers to evaluate the extent of protein movement within and across mitotic clones in follicle cells and imaginal discs, providing evidence of robust movement of GFP between the 2 sides of mitotic clones and frequently into non-recombined cells. These data suggest that, depending on the experimental setup and proteins of interest, inter-clonal diffusion of protein may alter the interpretation of clonal data in follicle cells. Here, we discuss these results and provide additional insight into the impact of ring canals in Drosophila somatic tissues. PMID:24406334

Increase in cytosolic calcium maintains plasma membrane integrity through the formation of microtubule ring structure in apoptotic cervical cancer cells induced by trichosanthin.

PubMed

Wang, Ping; Xu, Shujun; Zhao, Kai; Xiao, Bingxiu; Guo, Junming

2009-11-01

This study investigates the role of dysregulated cytosolic free calcium ([Ca(2+)]c) homeostasis on microtubule (MT) ring structure in apoptotic cervical cancer (HeLa) cells induced by trichosanthin (TCS), a type I ribosome inactivating protein (RIP). The TCS-induced decrease in cell viability was significantly enhanced in combination with the specific calcium chelator, EGTA-AM. Sequestration of [Ca(2+)]c markedly disrupted the special MT ring structure. Furthermore, TCS tended to increase LDH release, whereas no significant differences were observed until 48 h of the treatment. In contrast, combined addition of EGTA-AM or colchicine (an inhibitor of tubulin polymerization) significantly reinforced LDH release. The data suggest that TCS-elevated [Ca(2+)]c maintains plasma membrane integrity via the formation of the MT ring structure in apoptotic HeLa cells.

Targeting the Nociceptin/Orphanin FQ Receptor for Scleroderma Therapy

DTIC Science & Technology

2015-12-01

bottom well; the number of migrating cells is quantified by flow cytometry. In the aortic ring assay, freshly isolated thoracic aorta rings will...quantified by flow cytometry. In the aortic ring assay, freshly isolated thoracic aorta rings will be harvested and mounted in a small-vessel myograph. KO

Model of myosin node aggregation into a contractile ring: the effect of local alignment

NASA Astrophysics Data System (ADS)

Ojkic, Nikola; Wu, Jian-Qiu; Vavylonis, Dimitrios

2011-09-01

Actomyosin bundles frequently form through aggregation of membrane-bound myosin clusters. One such example is the formation of the contractile ring in fission yeast from a broad band of cortical nodes. Nodes are macromolecular complexes containing several dozens of myosin-II molecules and a few formin dimers. The condensation of a broad band of nodes into the contractile ring has been previously described by a search, capture, pull and release (SCPR) model. In SCPR, a random search process mediated by actin filaments nucleated by formins leads to transient actomyosin connections among nodes that pull one another into a ring. The SCPR model reproduces the transport of nodes over long distances and predicts observed clump-formation instabilities in mutants. However, the model does not generate transient linear elements and meshwork structures as observed in some wild-type and mutant cells during ring assembly. As a minimal model of node alignment, we added short-range aligning forces to the SCPR model representing currently unresolved mechanisms that may involve structural components, cross-linking and bundling proteins. We studied the effect of the local node alignment mechanism on ring formation numerically. We varied the new parameters and found viable rings for a realistic range of values. Morphologically, transient structures that form during ring assembly resemble those observed in experiments with wild-type and cdc25-22 cells. Our work supports a hierarchical process of ring self-organization involving components drawn together from distant parts of the cell followed by progressive stabilization.

Hybrid optical fiber add-drop filter based on wavelength dependent light coupling between micro/nano fiber ring and side-polished fiber

NASA Astrophysics Data System (ADS)

Yu, Jianhui; Jin, Shaoshen; Wei, Qingsong; Zang, Zhigang; Lu, Huihui; He, Xiaoli; Luo, Yunhan; Tang, Jieyuan; Zhang, Jun; Chen, Zhe

2015-01-01

In this paper, we report our experimental study on directly coupling a micro/nano fiber (MNOF) ring with a side-polished fiber(SPF). As a result of the study, the behavior of an add-drop filter was observed. The demonstrated add-drop filter explored the wavelength dependence of light coupling between a MNOF ring and a SPF. The characteristics of the filter and its performance dependence on the MNOF ring diameter were investigated experimentally. The investigation resulted in an empirically obtained ring diameter that showed relatively good filter performance. Since light coupling between a (MNOF) and a conventional single mode fiber has remained a challenge in the photonic integration community, the present study may provide an alternative way to couple light between a MNOF device and a conventional single mode fiber based device or system. The hybridization approach that uses a SPF as a platform to integrate a MNOF device may enable the realization of other all-fiber optical hybrid devices.

Hybrid optical fiber add-drop filter based on wavelength dependent light coupling between micro/nano fiber ring and side-polished fiber.

PubMed

Yu, Jianhui; Jin, Shaoshen; Wei, Qingsong; Zang, Zhigang; Lu, Huihui; He, Xiaoli; Luo, Yunhan; Tang, Jieyuan; Zhang, Jun; Chen, Zhe

2015-01-12

In this paper, we report our experimental study on directly coupling a micro/nano fiber (MNOF) ring with a side-polished fiber(SPF). As a result of the study, the behavior of an add-drop filter was observed. The demonstrated add-drop filter explored the wavelength dependence of light coupling between a MNOF ring and a SPF. The characteristics of the filter and its performance dependence on the MNOF ring diameter were investigated experimentally. The investigation resulted in an empirically obtained ring diameter that showed relatively good filter performance. Since light coupling between a (MNOF) and a conventional single mode fiber has remained a challenge in the photonic integration community, the present study may provide an alternative way to couple light between a MNOF device and a conventional single mode fiber based device or system. The hybridization approach that uses a SPF as a platform to integrate a MNOF device may enable the realization of other all-fiber optical hybrid devices.

Rho1- and Pkc1-dependent phosphorylation of the F-BAR protein Syp1 contributes to septin ring assembly.

PubMed

Merlini, Laura; Bolognesi, Alessio; Juanes, Maria Angeles; Vandermoere, Franck; Courtellemont, Thibault; Pascolutti, Roberta; Séveno, Martial; Barral, Yves; Piatti, Simonetta

2015-09-15

In many cell types, septins assemble into filaments and rings at the neck of cellular appendages and/or at the cleavage furrow to help compartmentalize the plasma membrane and support cytokinesis. How septin ring assembly is coordinated with membrane remodeling and controlled by mechanical stress at these sites is unclear. Through a genetic screen, we uncovered an unanticipated link between the conserved Rho1 GTPase and its effector protein kinase C (Pkc1) with septin ring stability in yeast. Both Rho1 and Pkc1 stabilize the septin ring, at least partly through phosphorylation of the membrane-associated F-BAR protein Syp1, which colocalizes asymmetrically with the septin ring at the bud neck. Syp1 is displaced from the bud neck upon Pkc1-dependent phosphorylation at two serines, thereby affecting the rigidity of the new-forming septin ring. We propose that Rho1 and Pkc1 coordinate septin ring assembly with membrane and cell wall remodeling partly by controlling Syp1 residence at the bud neck. © 2015 Merlini et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Nd:GdVO4 ring laser pumped by laser diodes

NASA Astrophysics Data System (ADS)

Hao, E. J.; Li, T.; Wang, Z. D.; Zhang, Y.

2013-02-01

The design and operation of a laser diode-pumped Nd:GdVO4 ring laser is described. A composite crystal (Nd:GdVO4/YVO4) with undoped ends is single-end pumped by a fiber-coupled laser diode (LD) at 808 nm. A four-mirror ring cavity is designed to keep the laser operating unidirectionally, which eliminates spatial hole burning in the standing-wave cavity. This laser can operate either as continuous wave (CW) or Q-switched. The single-frequency power obtained was 9.1 W at 1063 nm. Q-switched operation produced 0.23 mJ/pulse at 20 kHz in the fundamental laser.

Fiber Ring Optical Gyroscope (FROG)

NASA Technical Reports Server (NTRS)

1979-01-01

The design, construction, and testing of a one meter diameter fiber ring optical gyro, using 1.57 kilometers of single mode fiber, are described. The various noise components: electronic, thermal, mechanical, and optical, were evaluated. Both dc and ac methods were used. An attempt was made to measure the Earth rotation rate; however, the results were questionable because of the optical and electronic noise present. It was concluded that fiber ring optical gyroscopes using all discrete components have many serious problems that can only be overcome by discarding the discrete approach and adapting an all integrated optic technique that has the laser source, modulator, detector, beamsplitters, and bias element on a single chip.

Switchable dual-wavelength single-longitudinal-mode erbium fiber laser utilizing a dual-ring scheme with a saturable absorber

NASA Astrophysics Data System (ADS)

Yang, Zi-Qing; Huang, Tzu-Jung; Chang, Yao-Jen; Yeh, Chien-Hung; Chow, Chi-Wai; Chen, Jing-Heng; Chen, Kun-Huang

2018-06-01

In this work, we propose and demonstrate a switchable dual-wavelength erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) output. Here, a dual-ring (DR) structure with an unpumped EDF of 2 m is designed to achieve SLM oscillation. Five fiber Bragg gratings (FBGs) are applied in the laser cavity serving as the reflective element to generate different dual-wavelength outputs. In the measurement, six sets of generated dual-wavelengths with various mode-spacing (Δλ) can be achieved via the five FBGs. Additionally, the stability performance of the proposed EDF DR laser is also demonstrated.

Targeting MUC1-C suppresses polycomb repressive complex 1 in multiple myeloma.

PubMed

Tagde, Ashujit; Markert, Tahireh; Rajabi, Hasan; Hiraki, Masayuki; Alam, Maroof; Bouillez, Audrey; Avigan, David; Anderson, Kenneth; Kufe, Donald

2017-09-19

The polycomb repressive complex 1 (PRC1) includes the BMI1, RING1 and RING2 proteins. BMI1 is required for survival of multiple myeloma (MM) cells. The MUC1-C oncoprotein is aberrantly expressed by MM cells, activates MYC and is also necessary for MM cell survival. The present studies show that targeting MUC1-C with (i) stable and inducible silencing and CRISPR/Cas9 editing and (ii) the pharmacologic inhibitor GO-203, which blocks MUC1-C function, downregulates BMI1, RING1 and RING2 expression. The results demonstrate that MUC1-C drives BMI1 transcription by a MYC-dependent mechanism. MUC1-C thus promotes MYC occupancy on the BMI1 promoter and thereby activates BMI1 expression. We also show that the MUC1-C→MYC pathway induces RING2 expression. Moreover, in contrast to BMI1 and RING2, we found that MUC1-C drives RING1 by an NF-κB p65-dependent mechanism. Targeting MUC1-C and thereby the suppression of these key PRC1 proteins was associated with downregulation of the PRC1 E3 ligase activity as evidenced by decreases in ubiquitylation of histone H2A. Targeting MUC1-C also resulted in activation of the PRC1-repressed tumor suppressor genes, PTEN, CDNK2A and BIM . These findings identify a heretofore unrecognized role for MUC1-C in the epigenetic regulation of MM cells.

Controllable continuous evolution of electronic states in a single quantum ring

NASA Astrophysics Data System (ADS)

Chakraborty, Tapash; Manaselyan, Aram; Barseghyan, Manuk; Laroze, David

2018-02-01

An intense terahertz laser field is shown to have a profound effect on the electronic and optical properties of quantum rings where the isotropic and anisotropic quantum rings can now be treated on equal footing. We have demonstrated that in isotropic quantum rings the laser field creates unusual Aharonov-Bohm oscillations that are usually expected in anisotropic rings. Furthermore, we have shown that intense laser fields can restore the isotropic physical properties in anisotropic quantum rings. In principle, all types of anisotropies (structural, effective masses, defects, etc.) can evolve as in isotropic rings in our present approach. Most importantly, we have found a continuous evolution of the energy spectra and intraband optical characteristics of structurally anisotropic quantum rings to those of isotropic rings in a controlled manner with the help of a laser field.

Dynamic apical surface rings in superficial layer cells of koi Cyprinus carpio scale epidermis.

PubMed

DePasquale, J A

2016-09-01

This study examined the novel ring-shaped structures found in the apical surface of individual cells of the scale epidermis of koi Cyprinus carpio. These apical rings are highly dynamic structures with lifetimes ranging from a few to several minutes. While several ring forms were observed, the predominant ring morphology is circular or oval. Two distinct ring forms were identified and designated type I and type II. Type I rings have a well-defined outer border that encircles the surface microridges. Type II rings are smooth-surfaced, dinner-plate-like structures with membranous folds or compressed microridges in the centre. Type II rings appear less frequently than type I rings. Type I rings form spontaneously, arising from swollen or physically interrupted microridges but without initially perturbing the encircled microridges. After persisting for up to several minutes the ring closes in a centripetal movement to form a circular or irregular-shaped structure, the terminal disc. The terminal disc eventually disappears, leaving behind a submembranous vesicle-like structure, the terminal body. Type I rings can undergo multiple cycles of formation and closing. Recycling epidermal apical rings form through centrifugal expansion from the terminal disc followed by apparent contraction back to the disc structure, whereupon the cycle may repeat or cease. The findings demonstrate a novel skin surface structure in fishes and are discussed with respect to communication with the external aqueous environment. © 2016 The Fisheries Society of the British Isles.

CTLs, a new class of RING-H2 ubiquitin ligases uncovered by YEELL, a motif close to the RING domain that is present across eukaryotes.

PubMed

Jiménez-López, Domingo; Aguilar-Henonin, Laura; González-Prieto, Juan Manuel; Aguilar-Hernández, Victor; Guzmán, Plinio

2018-01-01

RING ubiquitin E3 ligases enclose a RING domain for ubiquitin ligase activity and associated domains and/or conserved motifs outside the RING domain that collectively facilitate their classification and usually reveal some of key information related to mechanism of action. Here we describe a new family of E3 ligases that encodes a RING-H2 domain related in sequence to the ATL and BTL RING-H2 domains. This family, named CTL, encodes a motif designed as YEELL that expands 21 amino acids next to the RING-H2 domain that is present across most eukaryotic lineages. E3 ubiquitin ligase BIG BROTHER is a plant CTL that regulates organ size, and SUMO-targeted ubiquitin E3 ligase RNF111/ARKADIA is a vertebrate CTL. Basal animal and vertebrate, as well as fungi species, encode a single CTL gene that constraints the number of paralogs observed in vertebrates. Conversely, as previously described in ATL and BTL families in plants, CTL genes range from a single copy in green algae and 3 to 5 copies in basal species to 9 to 35 copies in angiosperms. Our analysis describes key structural features of a novel family of E3 ubiquitin ligases as an integral component of the set of core eukaryotic genes.

Sensitivity analysis of linear CROW gyroscopes and comparison to a single-resonator gyroscope

NASA Astrophysics Data System (ADS)

Zamani-Aghaie, Kiarash; Digonnet, Michel J. F.

2013-03-01

This study presents numerical simulations of the maximum sensitivity to absolute rotation of a number of coupled resonator optical waveguide (CROW) gyroscopes consisting of a linear array of coupled ring resonators. It examines in particular the impact on the maximum sensitivity of the number of rings, of the relative spatial orientation of the rings (folded and unfolded), of various sequences of coupling ratios between the rings and various sequences of ring dimensions, and of the number of input/output waveguides (one or two) used to inject and collect the light. In all configurations the sensitivity is maximized by proper selection of the coupling ratio(s) and phase bias, and compared to the maximum sensitivity of a resonant waveguide optical gyroscope (RWOG) utilizing a single ring-resonator waveguide with the same radius and loss as each ring in the CROW. Simulations show that although some configurations are more sensitive than others, in spite of numerous claims to the contrary made in the literature, in all configurations the maximum sensitivity is independent of the number of rings, and does not exceed the maximum sensitivity of an RWOG. There are no sensitivity benefits to utilizing any of these linear CROWs for absolute rotation sensing. For equal total footprint, an RWOG is √N times more sensitive, and it is easier to fabricate and stabilize.

CTLs, a new class of RING-H2 ubiquitin ligases uncovered by YEELL, a motif close to the RING domain that is present across eukaryotes

PubMed Central

Jiménez-López, Domingo; Aguilar-Henonin, Laura; González-Prieto, Juan Manuel; Aguilar-Hernández, Victor

2018-01-01

RING ubiquitin E3 ligases enclose a RING domain for ubiquitin ligase activity and associated domains and/or conserved motifs outside the RING domain that collectively facilitate their classification and usually reveal some of key information related to mechanism of action. Here we describe a new family of E3 ligases that encodes a RING-H2 domain related in sequence to the ATL and BTL RING-H2 domains. This family, named CTL, encodes a motif designed as YEELL that expands 21 amino acids next to the RING-H2 domain that is present across most eukaryotic lineages. E3 ubiquitin ligase BIG BROTHER is a plant CTL that regulates organ size, and SUMO-targeted ubiquitin E3 ligase RNF111/ARKADIA is a vertebrate CTL. Basal animal and vertebrate, as well as fungi species, encode a single CTL gene that constraints the number of paralogs observed in vertebrates. Conversely, as previously described in ATL and BTL families in plants, CTL genes range from a single copy in green algae and 3 to 5 copies in basal species to 9 to 35 copies in angiosperms. Our analysis describes key structural features of a novel family of E3 ubiquitin ligases as an integral component of the set of core eukaryotic genes. PMID:29324855

Design and use of a folded four-ring double-tuned birdcage coil for rat brain sodium imaging at 9.4 T

NASA Astrophysics Data System (ADS)

Ha, YongHyun; Choi, Chang-Hoon; Worthoff, Wieland A.; Shymanskaya, Aliaksandra; Schöneck, Michael; Willuweit, Antje; Felder, Jörg; Shah, N. Jon

2018-01-01

A folded four-ring quadrature birdcage coil was designed and constructed with a double-tune configuration of an outer high-pass coil for 1H (400 MHz) and inner low-pass coil for 23Na (105.72 MHz at 9.4 T). The coil was evaluated on the bench and in the scanner, comparing its performance with that of single-tuned coils and a large four-ring coil. All coils were tuned and matched and the isolation between two quadrature ports was found to be better than -13.7 dB for 1H and -27 dB for 23Na. Signal-to-noise ratios (SNRs) were calculated and 23Na flip angle maps were acquired. 23Na SNR of the folded four-ring reached ∼93% of that obtained with the single-tuned coil. A set of in vivo1H and 23Na axial images to cover the whole rat brain were obtained. The performance of the folded four-ring coil and its benefit for 23Na imaging experiments have been demonstrated. This proposed four-ring coil could avoid length restrictions, e.g. the shoulders, by folding the outer rings vertically. This facilitates the construction of double-tuned four-ring birdcage coils just to fit the head, leading to higher filling factors and better SNR.

Near-atomic-resolution cryo-EM analysis of the Salmonella T3S injectisome basal body.

PubMed

Worrall, L J; Hong, C; Vuckovic, M; Deng, W; Bergeron, J R C; Majewski, D D; Huang, R K; Spreter, T; Finlay, B B; Yu, Z; Strynadka, N C J

2016-12-14

The type III secretion (T3S) injectisome is a specialized protein nanomachine that is critical for the pathogenicity of many Gram-negative bacteria, including purveyors of plague, typhoid fever, whooping cough, sexually transmitted infections and major nosocomial infections. This syringe-shaped 3.5-MDa macromolecular assembly spans both bacterial membranes and that of the infected host cell. The internal channel formed by the injectisome allows for the direct delivery of partially unfolded virulence effectors into the host cytoplasm. The structural foundation of the injectisome is the basal body, a molecular lock-nut structure composed predominantly of three proteins that form highly oligomerized concentric rings spanning the inner and outer membranes. Here we present the structure of the prototypical Salmonella enterica serovar Typhimurium pathogenicity island 1 basal body, determined using single-particle cryo-electron microscopy, with the inner-membrane-ring and outer-membrane-ring oligomers defined at 4.3 Å and 3.6 Å resolution, respectively. This work presents the first, to our knowledge, high-resolution structural characterization of the major components of the basal body in the assembled state, including that of the widespread class of outer-membrane portals known as secretins.

Phase 1 Safety, Pharmacokinetics, and Pharmacodynamics of Dapivirine and Maraviroc Vaginal Rings: a Double-Blind Randomized Trial

PubMed Central

Chen, Beatrice A.; Panther, Lori; Marzinke, Mark A.; Hendrix, Craig W.; Hoesley, Craig J.; van der Straten, Ariane; Husnik, Marla J.; Soto-Torres, Lydia; Nel, Annalene; Johnson, Sherri; Richardson-Harman, Nicola; Rabe, Lorna K.; Dezzutti, Charlene S.

2015-01-01

Background Variable adherence limits effectiveness of daily oral and intravaginal tenofovir-containing pre-exposure prophylaxis. Monthly vaginal antiretroviral rings are one approach to improve adherence and drug delivery. Methods MTN-013/IPM 026, a multi-site, double-blind, randomized, placebo-controlled trial in 48 HIV-negative U.S. women, evaluated vaginal rings containing dapivirine (25 mg) and maraviroc (100 mg), dapivirine-only, maraviroc-only, and placebo used continuously for 28 days. Safety was assessed by adverse events. Drug concentrations were quantified in plasma, cervicovaginal fluid (CVF), and cervical tissue. Cervical biopsy explants were challenged with HIV ex vivo to evaluate pharmacodynamics. Results There was no difference in related genitourinary adverse events between treatment arms compared to placebo. Dapivirine and maraviroc concentrations rose higher initially before falling more rapidly with the combination ring compared to relatively stable concentrations with the single drug rings. Dapivirine concentrations in CVF were 1 and 5 log10 greater than cervical tissue and plasma for both rings. Maraviroc was consistently detected only in CVF. Dapivirine and maraviroc CVF and dapivirine tissue concentrations dropped rapidly after ring removal. Cervical tissue showed a significant inverse linear relationship between HIV replication and dapivirine levels. Conclusions In this first study of a combination microbicide vaginal ring, all four rings were safe and well tolerated. Tissue dapivirine concentrations were 1,000 times greater than plasma concentrations and single drug rings had more stable pharmacokinetics. Dapivirine, but not maraviroc, demonstrated concentration-dependent inhibition of HIV-1 infection in cervical tissue. Since maraviroc concentrations were consistently detectable only in CVF and not in plasma, improved drug release of maraviroc rings is needed. PMID:26034880

Phase 1 Safety, Pharmacokinetics, and Pharmacodynamics of Dapivirine and Maraviroc Vaginal Rings: A Double-Blind Randomized Trial.

PubMed

Chen, Beatrice A; Panther, Lori; Marzinke, Mark A; Hendrix, Craig W; Hoesley, Craig J; van der Straten, Ariane; Husnik, Marla J; Soto-Torres, Lydia; Nel, Annalene; Johnson, Sherri; Richardson-Harman, Nicola; Rabe, Lorna K; Dezzutti, Charlene S

2015-11-01

Variable adherence limits effectiveness of daily oral and intravaginal tenofovir-containing pre-exposure prophylaxis. Monthly vaginal antiretroviral rings are one approach to improve adherence and drug delivery. MTN-013/IPM 026, a multisite, double-blind, randomized, placebo-controlled trial in 48 HIV-negative US women, evaluated vaginal rings containing dapivirine (DPV) (25 mg) and maraviroc (MVC) (100 mg), DPV only, MVC only, and placebo used continuously for 28 days. Safety was assessed by adverse events. Drug concentrations were quantified in plasma, cervicovaginal fluid (CVF), and cervical tissue. Cervical biopsy explants were challenged with HIV ex vivo to evaluate pharmacodynamics. There was no difference in related genitourinary adverse events between treatment arms compared with placebo. DPV and MVC concentrations rose higher initially before falling more rapidly with the combination ring compared with relatively stable concentrations with the single-drug rings. DPV concentrations in CVF were 1 and 5 log10 greater than cervical tissue and plasma for both rings. MVC was consistently detected only in CVF. DPV and MVC CVF and DPV tissue concentrations dropped rapidly after ring removal. Cervical tissue showed a significant inverse linear relationship between HIV replication and DPV levels. In this first study of a combination microbicide vaginal ring, all 4 rings were safe and well tolerated. Tissue DPV concentrations were 1000 times greater than plasma concentrations and single drug rings had more stable pharmacokinetics. DPV, but not MVC, demonstrated concentration-dependent inhibition of HIV-1 infection in cervical tissue. Because MVC concentrations were consistently detectable only in CVF and not in plasma, improved drug release of MVC rings is needed.

Proceedings of the 1993 Particle Accelerator Conference Held in Washington, DC on May 17-20, 1993. Volume 3

DTIC Science & Technology

1993-05-20

mm-mrad 10 mm-md I. INTRODUCTION Higher -order modes (HOMs) of the SR single cell cavityThe 20-MeV linac beam at the Argonne Chemistry are studied by...energy proton storage rings: RHIC and the SSC. I. INTRODUCTION We have proposed to build spin rotators with two k transverse wigglers of many poles...integral of gauge field; beam Is always polarized, the magnetic potential flux line of (4) edot quantization of path integral in sate sae bunch spin are

Pseudo-single-bunch mode for a 100 MHz storage ring serving soft X-ray timing experiments

NASA Astrophysics Data System (ADS)

Olsson, T.; Leemann, S. C.; Georgiev, G.; Paraskaki, G.

2018-06-01

At many storage rings for synchrotron light production there is demand for serving both high-flux and timing users simultaneously. Today this is most commonly achieved by operating inhomogeneous fill patterns, but this is not preferable for rings that employ passive harmonic cavities to damp instabilities and increase Touschek lifetime. For these rings, inhomogeneous fill patterns could severely reduce the effect of the harmonic cavities. It is therefore of interest to develop methods to serve high-flux and timing users simultaneously without requiring gaps in the fill pattern. One such method is pseudo-single-bunch (PSB), where one bunch in the bunch train is kicked onto another orbit by a fast stripline kicker. The light emitted from the kicked bunch can then be separated by an aperture in the beamline. Due to recent developments in fast kicker design, PSB operation in multibunch mode is within reach for rings that operate with a 100 MHz RF system, such as the MAX IV and Solaris storage rings. This paper describes machine requirements and resulting performance for such a mode at the MAX IV 1.5 GeV storage ring. A solution for serving all beamlines is discussed as well as the consequences of beamline design and operation in the soft X-ray energy range.

Development of large volume double ring penning plasma discharge source for efficient light emissions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prakash, Ram; Vyas, Gheesa Lal; Jain, Jalaj

In this paper, the development of large volume double ring Penning plasma discharge source for efficient light emissions is reported. The developed Penning discharge source consists of two cylindrical end cathodes of stainless steel having radius 6 cm and a gap 5.5 cm between them, which are fitted in the top and bottom flanges of the vacuum chamber. Two stainless steel anode rings with thickness 0.4 cm and inner diameters 6.45 cm having separation 2 cm are kept at the discharge centre. Neodymium (Nd{sub 2}Fe{sub 14}B) permanent magnets are physically inserted behind the cathodes for producing nearly uniform magnetic fieldmore » of {approx}0.1 T at the center. Experiments and simulations have been performed for single and double anode ring configurations using helium gas discharge, which infer that double ring configuration gives better light emissions in the large volume Penning plasma discharge arrangement. The optical emission spectroscopy measurements are used to complement the observations. The spectral line-ratio technique is utilized to determine the electron plasma density. The estimated electron plasma density in double ring plasma configuration is {approx}2 Multiplication-Sign 10{sup 11} cm{sup -3}, which is around one order of magnitude larger than that of single ring arrangement.« less

Development of large volume double ring penning plasma discharge source for efficient light emissions.

PubMed

Prakash, Ram; Vyas, Gheesa Lal; Jain, Jalaj; Prajapati, Jitendra; Pal, Udit Narayan; Chowdhuri, Malay Bikas; Manchanda, Ranjana

2012-12-01

In this paper, the development of large volume double ring Penning plasma discharge source for efficient light emissions is reported. The developed Penning discharge source consists of two cylindrical end cathodes of stainless steel having radius 6 cm and a gap 5.5 cm between them, which are fitted in the top and bottom flanges of the vacuum chamber. Two stainless steel anode rings with thickness 0.4 cm and inner diameters 6.45 cm having separation 2 cm are kept at the discharge centre. Neodymium (Nd(2)Fe(14)B) permanent magnets are physically inserted behind the cathodes for producing nearly uniform magnetic field of ~0.1 T at the center. Experiments and simulations have been performed for single and double anode ring configurations using helium gas discharge, which infer that double ring configuration gives better light emissions in the large volume Penning plasma discharge arrangement. The optical emission spectroscopy measurements are used to complement the observations. The spectral line-ratio technique is utilized to determine the electron plasma density. The estimated electron plasma density in double ring plasma configuration is ~2 × 10(11) cm(-3), which is around one order of magnitude larger than that of single ring arrangement.

Surface and interior views on origins of two types of banded spherulites in poly(nonamethylene terephthalate).

PubMed

Woo, Eamor M; Nurkhamidah, Siti; Chen, Yu-Fan

2011-10-21

Top-surface and three-dimensional views of Type-1 and Type-2 of ring-banded spherulites in poly(nonamethylene terephthalate) (PNT) in thicker bulk crystallized on a nucleating potassium bromide (KBr) substrate were examined using various microscopy techniques: scanning electron microscopy (SEM), polarized-optical microscopy (POM), and atomic-force microscopy (AFM). In PNT crystallized at higher crystallization temperature (T(c)) with heterogeneous nucleating substrate, typically two types of ring-banded spherulites are present that differ significantly in patterns and ring spacings: Type-1 Type-2 (single- and double-ring-banded spherulites). Three-dimensional view on fractured spherulites in bulk PNT samples reveals that the single-ring-banded spherulite (Type-1) tends to be well-rounded spheres as they are nucleated homogeneously from bulk; the double-ring-banded spherulite (Type-2) is concentric hemisphere or truncated sphere shells owing to be nucleated from bottom. With confined thickness of films, the 3-D hemispheres in PNT may become truncated into multi-shell annular cones or arcs when thickness or growth is restricted. Based on the top-surface vs. interior views of banded lamellar assembly, origins and inner structures of dual types of ring bands in PNT were examined in greater details. This journal is © the Owner Societies 2011

A signet-ring cell melanoma arising from a medium-sized congenital melanocytic nevus in an adult: A case report and literature review.

PubMed

Tajima, Shogo; Koda, Kenji

2015-07-01

Patients with congenital nevus, especially giant congenital melanocytic nevus (CMN) measuring >20 cm, are known to be at elevated risk of developing melanomas, especially during the first and second decades of life. Melanomas rarely develop in patients with small and medium-sized CMNs, but if they do, they occur during the fourth and fifth decades of life. We present a case of a rapidly enlarging signet-ring cell melanoma (over 3 months) that arose from a medium-sized CMN in a 57-year-old Japanese man. Only 11 other cases of signet-ring cell melanomas at the primary site have been reported. On the basis of morphology alone, it is difficult to diagnose a nodule appearing in a CMN as a signet-ring cell melanoma, because even a benign melanocytic nevus can appear as signet-ring cell morphology. Moreover, a rapidly growing proliferative nodule (PN) more often develops in a CMN than melanoma; PNs may at times exhibit enough atypia to be comparable to melanomas. In our case, loss of p16 expression in the melanoma distinguished it from the nevus cells and was helpful in making the correct diagnosis. Clinical information, such as the patient's age, was also useful in establishing the diagnosis. © 2015 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.

Synthesis of novel 2-cyano substituted glycyrrhetinic acid derivatives as inhibitors of cancer cells growth and NO production in LPS-activated J-774 cells.

PubMed

Salomatina, Oksana V; Markov, Andrey V; Logashenko, Evgeniya B; Korchagina, Dina V; Zenkova, Marina A; Salakhutdinov, Nariman F; Vlassov, Valentin V; Tolstikov, Genrikh A

2014-01-01

Here we report the synthesis and biological activity of new semi-synthetic derivatives of naturally occurring glycyrrhetinic acid bearing a 2-cyano-3-oxo-1-en moiety in the A-ring and double bonds and carbonyl groups in the C, D and E rings. Bioassays using murine macrophage-like and tumor cells show that compound 4, which differs from Soloxolone methyl by the absence of a 9(11)-double bond in the C-ring, displays anti-inflammatory and inhibitory activities with respect to tumor cells with a high selectivity index value. Copyright © 2013 Elsevier Ltd. All rights reserved.

Secondary signet-ring cell adenocarcinoma of urinary bladder from a gastric primary.

PubMed

Sharma, Pramod K; Vijay, Mukesh K; Das, Ranjit K; Chatterjee, Uttara

2011-05-01

Primary bladder tumor is a frequent urological malignancy, whereas the incidence of secondary bladder tumor from a distant organ is quite rare. Secondary bladder neoplasms represent 1% of all malignant bladder tumors, of which distant metastases from stomach account for about 4% of cases. We present the case of a 30-year-old male who underwent partial gastrectomy for Signet-ring cell carcinoma of the stomach and presented 2 years later with hematuria. On computerized tomography scan, a bladder tumor was found which was resected cystoscopically. The histopathological examination revealed secondary Signet-ring cell adenocarcinoma of the urinary bladder.

Rho1- and Pkc1-dependent phosphorylation of the F-BAR protein Syp1 contributes to septin ring assembly

PubMed Central

Merlini, Laura; Bolognesi, Alessio; Juanes, Maria Angeles; Vandermoere, Franck; Courtellemont, Thibault; Pascolutti, Roberta; Séveno, Martial; Barral, Yves; Piatti, Simonetta

2015-01-01

In many cell types, septins assemble into filaments and rings at the neck of cellular appendages and/or at the cleavage furrow to help compartmentalize the plasma membrane and support cytokinesis. How septin ring assembly is coordinated with membrane remodeling and controlled by mechanical stress at these sites is unclear. Through a genetic screen, we uncovered an unanticipated link between the conserved Rho1 GTPase and its effector protein kinase C (Pkc1) with septin ring stability in yeast. Both Rho1 and Pkc1 stabilize the septin ring, at least partly through phosphorylation of the membrane-associated F-BAR protein Syp1, which colocalizes asymmetrically with the septin ring at the bud neck. Syp1 is displaced from the bud neck upon Pkc1-dependent phosphorylation at two serines, thereby affecting the rigidity of the new-forming septin ring. We propose that Rho1 and Pkc1 coordinate septin ring assembly with membrane and cell wall remodeling partly by controlling Syp1 residence at the bud neck. PMID:26179915

The monomeric, tetrameric, and fibrillar organization of Fib: the dynamic building block of the bacterial linear motor of Spiroplasma melliferum BC3.

PubMed

Cohen-Krausz, Sara; Cabahug, Pamela C; Trachtenberg, Shlomo

2011-07-08

Spiroplasmas belong to the class Mollicutes, representing the minimal, free-living, and self-replicating forms of life. Spiroplasmas are helical wall-less bacteria and the only ones known to swim by means of a linear motor (rather than the near-universal rotary bacterial motor). The linear motor follows the shortest path along the cell's helical membranal tube. The motor is composed of a flat monolayered ribbon of seven parallel fibrils and is believed to function in controlling cell helicity and motility through dynamic, coordinated, differential length changes in the fibrils. The latter cause local perturbations of helical symmetry, which are essential for net directional displacement in environments with a low Reynolds number. The underlying fibrils' core building block is a circular tetramer of the 59-kDa protein Fib. The fibrils' differential length changes are believed to be driven by molecular switching of Fib, leading consequently to axial ratio and length changes in tetrameric rings. Using cryo electron microscopy, diffractometry, single-particle analysis of isolated ribbons, and sequence analyses of Fib, we determined the overall molecular organization of the Fib monomer, tetramer, fibril, and linear motor of Spiroplasma melliferum BC3 that underlies cell geometry and motility. Fib appears to be a bidomained molecule, of which the N-terminal half is apparently a globular phosphorylase. By a combination of reversible rotation and diagonal shift of Fib monomers, the tetramer adopts either a cross-like nonhanded conformation or a ring-like handed conformation. The sense of Fib rotation may determine the handedness of the linear motor and, eventually, of the cell. A further change in the axial ratio of the ring-like tetramers controls fibril lengths and the consequent helical geometry. Analysis of tetramer quadrants from adjacent fibrils clearly demonstrates local differential fibril lengths. Copyright © 2011 Elsevier Ltd. All rights reserved.

Experimental Performance of a Single-Mode Ytterbium-doped Fiber Ring Laser with Intracavity Modulator

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2012-01-01

We have developed a linearly polarized Ytterbium-doped fiber ring laser with a single longitudinal mode output at 1064 run. A fiber-coupled intracavity phase modulator ensured mode-hop free operation and allowed fast frequency tuning. The fiber laser was locked with high stability to an iodine-stabilized laser, showing a frequency noise suppression of a factor approx 10 (exp 5) at 1 mHz

Synthesis and structure-activity relationships of constrained heterocyclic analogues of combretastatin A4.

PubMed

Arthuis, Martin; Pontikis, Renée; Chabot, Guy G; Seguin, Johanne; Quentin, Lionel; Bourg, Stéphane; Morin-Allory, Luc; Florent, Jean-Claude

2011-09-05

A series of combretastatin A4 (CA4) analogues with a lactam or lactone ring fused to the trimethoxyphenyl or the B-phenyl moiety were synthesized in an efficient and stereoselective manner by using a domino Heck-Suzuki-Miyaura coupling reaction. The vascular-disrupting potential of these conformationally restricted CA4 analogues was assessed by various in vitro assays: inhibition of tubulin polymerization, modification of endothelial cell morphology, and disruption of endothelial cell cords. Compounds were also evaluated for their growth inhibitory effects against murine and human tumor cells. B-ring-constrained derivatives that contain an oxindole ring (in contrast to compounds with a benzofuranone ring) as well as analogues bearing a six-membered lactone core fused to the trimethoxyphenyl ring are endowed with significant biological activity. The most potent compound of this series (oxindole 9 b) is of particular interest, as it combines chemical stability and a biological activity profile characteristic of a vascular-disrupting agent. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of single-file diffusion in one-dimensional dusty plasma

NASA Astrophysics Data System (ADS)

Theisen, W. L.; Sheridan, T. E.

2010-11-01

Single-file diffusion occurs in one-dimensional systems when particles cannot pass each other and the mean-squared displacement (msd) of these particles increases with time t. Diffusive processes that follow Ficks law predict that the msd increases as t, however, single-file diffusion is sub-Fickean meaning that the msd is predicted to increase as t^1/2. One-dimensional dusty plasma rings have been created under strongly coupled, over-damped conditions. Particle position data from these rings will be analyzed to determine the scaling of the msd with time. Results will be compared with predictions of single-file diffusion theory.

The TubR-centromere complex adopts a double-ring segrosome structure in Type III partition systems.

PubMed

Martín-García, Bárbara; Martín-González, Alejandro; Carrasco, Carolina; Hernández-Arriaga, Ana M; Ruíz-Quero, Rubén; Díaz-Orejas, Ramón; Aicart-Ramos, Clara; Moreno-Herrero, Fernando; Oliva, María A

2018-05-14

In prokaryotes, the centromere is a specialized segment of DNA that promotes the assembly of the segrosome upon binding of the Centromere Binding Protein (CBP). The segrosome structure exposes a specific surface for the interaction of the CBP with the motor protein that mediates DNA movement during cell division. Additionally, the CBP usually controls the transcriptional regulation of the segregation system as a cell cycle checkpoint. Correct segrosome functioning is therefore indispensable for accurate DNA segregation. Here, we combine biochemical reconstruction and structural and biophysical analysis to bring light to the architecture of the segrosome complex in Type III partition systems. We present the particular features of the centromere site, tubC, of the model system encoded in Clostridium botulinum prophage c-st. We find that the split centromere site contains two different iterons involved in the binding and spreading of the CBP, TubR. The resulting nucleoprotein complex consists of a novel double-ring structure that covers part of the predicted promoter. Single molecule data provides a mechanism for the formation of the segrosome structure based on DNA bending and unwinding upon TubR binding.

Novel Method for Differentiating Histological Types of Gastric Adenocarcinoma by Using Confocal Raman Microspectroscopy

PubMed Central

Hsu, Chih-Wei; Huang, Chia-Chi; Sheu, Jeng-Horng; Lin, Chia-Wen; Lin, Lien-Fu; Jin, Jong-Shiaw; Chau, Lai-Kwan; Chen, Wenlung

2016-01-01

Gastric adenocarcinoma, a single heterogeneous disease with multiple epidemiological and histopathological characteristics, accounts for approximately 10% of cancers worldwide. It is categorized into four histological types: papillary adenocarcinoma (PAC), tubular adenocarcinoma (TAC), mucinous adenocarcinoma (MAC), and signet ring cell adenocarcinoma (SRC). Effective differentiation of the four types of adenocarcinoma will greatly improve the treatment of gastric adenocarcinoma to increase its five-year survival rate. We reported here the differentiation of the four histological types of gastric adenocarcinoma from the molecularly structural viewpoint of confocal Raman microspectroscopy. In total, 79 patients underwent laparoscopic or open radical gastrectomy during 2008–2011: 21 for signet ring cell carcinoma, 21 for tubular adenocarcinoma, 14 for papillary adenocarcinoma, 6 for mucinous carcinoma, and 17 for normal gastric mucosas obtained from patients underwent operation for other benign lesions. Clinical data were retrospectively reviewed from medical charts, and Raman data were processed and analyzed by using principal component analysis (PCA) and linear discriminant analysis (LDA). Two-dimensional plots of PCA and LDA clearly demonstrated that the four histological types of gastric adenocarcinoma could be differentiated, and confocal Raman microspectroscopy provides potentially a rapid and effective method for differentiating SRC and MAC from TAC or PAC. PMID:27472385

Wood anatomical analysis of Alnus incana and Betula pendula injured by a debris-flow event.

PubMed

Arbellay, Estelle; Stoffel, Markus; Bollschweiler, Michelle

2010-10-01

Vessel chronologies in ring-porous species have been successfully employed in the past to extract the climate signal from tree rings. Environmental signals recorded in vessels of ring-porous species have also been used in previous studies to reconstruct discrete events of drought, flooding and insect defoliation. However, very little is known about the ability of diffuse-porous species to record environmental signals in their xylem cells. Moreover, time series of wood anatomical features have only rarely been used to reconstruct former geomorphic events. This study was therefore undertaken to characterize the wood anatomical response of diffuse-porous Alnus incana (L.) Moench and Betula pendula Roth to debris-flow-induced wounding. Tree microscopic response to wounding was assessed through the analysis of wood anatomical differences between injured rings formed in the debris-flow event year and uninjured rings formed in the previous year. The two ring types were examined close and opposite to the injury in order to determine whether wound effects on xylem cells decrease with increasing tangential distance from the injury. Image analysis was used to measure vessel parameters as well as fiber and parenchyma cell (FPC) parameters. The results of this study indicate that injured rings are characterized by smaller vessels as compared with uninjured rings. By contrast, FPC parameters were not found to significantly differ between injured and uninjured rings. Vessel and FPC parameters mainly remained constant with increasing tangential distance from the injury, except for a higher proportion of vessel lumen area opposite to the injury within A. incana. This study highlights the existence of anatomical tree-ring signatures-in the form of smaller vessels-related to past debris-flow activity and addresses a new methodological approach to date injuries inflicted on trees by geomorphic processes.

Product suitability of wood...determined by density gradients across growth rings

Treesearch

Robert M. Echols

1972-01-01

The suitability of wood for various uses can be determined by synthesizing single growth-ring density curves from accumulated means of wood density classes. Wood density gradients across growth rings were measured in large increment cores from 46-year-old ponderosa pines (Pinus ponderosa Laws.) by using X-rays. Of the 48 trees analyzed, 36 had been...

Label-free microfluidic enrichment of ring-stage Plasmodium falciparum-infected red blood cells using non-inertial hydrodynamic lift.

PubMed

Geislinger, Thomas M; Chan, Sherwin; Moll, Kirsten; Wixforth, Achim; Wahlgren, Mats; Franke, Thomas

2014-09-20

Understanding of malaria pathogenesis caused by Plasmodium falciparum has been greatly deepened since the introduction of in vitro culture system, but the lack of a method to enrich ring-stage parasites remains a technical challenge. Here, a novel way to enrich red blood cells containing parasites in the early ring stage is described and demonstrated. A simple, straight polydimethylsiloxane microchannel connected to two syringe pumps for sample injection and two height reservoirs for sample collection is used to enrich red blood cells containing parasites in the early ring stage (8-10 h p.i.). The separation is based on the non-inertial hydrodynamic lift effect, a repulsive cell-wall interaction that enables continuous and label-free separation with deformability as intrinsic marker. The possibility to enrich red blood cells containing P. falciparum parasites at ring stage with a throughput of ~12,000 cells per hour and an average enrichment factor of 4.3 ± 0.5 is demonstrated. The method allows for the enrichment of red blood cells early after the invasion by P. falciparum parasites continuously and without any need to label the cells. The approach promises new possibilities to increase the sensitivity of downstream analyses like genomic- or diagnostic tests. The device can be produced as a cheap, disposable chip with mass production technologies and works without expensive peripheral equipment. This makes the approach interesting for the development of new devices for field use in resource poor settings and environments, e.g. with the aim to increase the sensitivity of microscope malaria diagnosis.

Phase I Study of Cetuximab With RO4929097 in Metastatic Colorectal Cancer

ClinicalTrials.gov

2015-05-15

Colon Mucinous Adenocarcinoma; Colon Signet Ring Cell Adenocarcinoma; Rectal Mucinous Adenocarcinoma; Rectal Signet Ring Cell Adenocarcinoma; Recurrent Colon Carcinoma; Recurrent Rectal Carcinoma; Stage IVA Colon Cancer; Stage IVA Rectal Cancer; Stage IVB Colon Cancer; Stage IVB Rectal Cancer

Diffuse-type Gastric Mucinous and Signet Ring Cell Adenocarcinoma in a Captive California King Snake (Lampropeltis getula californiae).

PubMed

Hsueh, C-S; Li, W-T; Jeng, C-R; Pang, V F; Chang, H-W

2018-04-01

An adult female California king snake (Lampropeltis getula californiae) housed in Taipei Zoo was presented with a 2-week history of anorexia, fatigue and abdominal swelling. Exploratory laparotomy revealed a gastric mass with two circular perforations and multiple mottled white to beige protuberances along the mucosal surface. Histologically, the gastric mass showed an invasive, transmural growth of epithelial cells arranged in nests, lobules, acini and sheets in the mucosa and submucosa that progressively transformed into signet ring cells in the muscularis externa and subserosa. All of the neoplastic cells expressed pan-cytokeratin immunohistochemically. Based on the World Health Organization histological criteria, a diagnosis of diffuse-type gastric mucinous and signet ring cell adenocarcinoma was made. Copyright © 2018 Elsevier Ltd. All rights reserved.

Two-mode division multiplexing in a silicon-on-insulator ring resonator.

PubMed

Dorin, Bryce A; Ye, Winnie N

2014-02-24

Mode-division multiplexing (MDM) is an emerging multiple-input multiple-output method, utilizing multimode waveguides to increase channel numbers. In the past, silicon-on-insulator (SOI) devices have been primarily focused on single-mode waveguides. We present the design and fabrication of a two-mode SOI ring resonator for MDM systems. By optimizing the device parameters, we have ensured that each mode is treated equally within the ring. Using adiabatic Bezier curves in the ring bends, our ring demonstrated a signal-to-crosstalk ratio above 18 dB for both modes at the through and drop ports. We conclude that the ring resonator has the potential for filtering and switching for MDM systems on SOI.

Fast and accurate focusing analysis of large photon sieve using pinhole ring diffraction model.

PubMed

Liu, Tao; Zhang, Xin; Wang, Lingjie; Wu, Yanxiong; Zhang, Jizhen; Qu, Hemeng

2015-06-10

In this paper, we developed a pinhole ring diffraction model for the focusing analysis of a large photon sieve. Instead of analyzing individual pinholes, we discuss the focusing of all of the pinholes in a single ring. An explicit equation for the diffracted field of individual pinhole ring has been proposed. We investigated the validity range of this generalized model and analytically describe the sufficient conditions for the validity of this pinhole ring diffraction model. A practical example and investigation reveals the high accuracy of the pinhole ring diffraction model. This simulation method could be used for fast and accurate focusing analysis of a large photon sieve.

Antitumor effects of hydroxycamptothecin-loaded poly[ethylene glycol]-poly [gamma-benzyl-L-glutamate] micelles against oral squamous cell carcinoma.

PubMed

Ding, Xue-Qiang; Chen, Dan; Wang, An-Xun; Li, Su; Chen, Yu; Wang, Ji

2007-01-01

Therapeutic use of hydroxycamptothecin (HCPT), a promising antitumor agent, is limited by its poor solubility and rapid destruction. Amphiphilic block copolymer micelle carriers possess significant potential for improving drug solubility and stability. Poly[ethylene glycol]-poly[gamma-benzyl-L-glutamate] (PEG-PBLG) micelles were prepared and loaded with the active lactone form of HCPT using an uncomplicated dialysis method. HPLC and scanning electron microscopy studies revealed an encapsulation efficiency of 56.8% and a core-shell figure with a mean diameter of 200 nm. Encapsulated HCPT lactone was compared with the less active, open ring-carboxylated HCPT-Na+ soluble form generated in vivo from the free active lactone for activity against oral squamous cell carcinoma. Cytotoxicity in vitro was measured in cultured Tca8113 cells by the MTT assay and microscopy techniques. The golden hamster cheek pouch squamous cell carcinoma model was employed for in vivo studies; encapsulated lactone and open ring-carboxylated forms of HCPT were administered intraperitoneally, followed by determinations of tumor growth rate and inhibition ratio. PEG-PBLG micelles were not cytotoxic in vitro. At 48 h of treatment, open ring-carboxylated HCPT proved significantly more cytotoxic in vitro than encapsulated HCPT lactone. At 96 h, however, the open ring-carboxylated and encapsulated drugs displayed comparable in vitro cytotoxicities. In the in vivo squamous cell carcinoma model, encapsulated HCPT lactone produced greater and more prolonged tumor suppression compared to the open ring-carboxylated form. The antitumor effects of HCPT/PEG-PBLG micelles against oral squamous cell carcinoma in vivo are concluded to be superior to those exerted by open ring-carboxylated HCPT.

Biophysical modelling of intra-ring variations in tracheid features and wood density of Pinus pinaster trees exposed to seasonal droughts.

PubMed

Wilkinson, Sarah; Ogée, Jérôme; Domec, Jean-Christophe; Rayment, Mark; Wingate, Lisa

2015-03-01

Process-based models that link seasonally varying environmental signals to morphological features within tree rings are essential tools to predict tree growth response and commercially important wood quality traits under future climate scenarios. This study evaluated model portrayal of radial growth and wood anatomy observations within a mature maritime pine (Pinus pinaster (L.) Aït.) stand exposed to seasonal droughts. Intra-annual variations in tracheid anatomy and wood density were identified through image analysis and X-ray densitometry on stem cores covering the growth period 1999-2010. A cambial growth model was integrated with modelled plant water status and sugar availability from the soil-plant-atmosphere transfer model MuSICA to generate estimates of cell number, cell volume, cell mass and wood density on a weekly time step. The model successfully predicted inter-annual variations in cell number, ring width and maximum wood density. The model was also able to predict the occurrence of special anatomical features such as intra-annual density fluctuations (IADFs) in growth rings. Since cell wall thickness remained surprisingly constant within and between growth rings, variations in wood density were primarily the result of variations in lumen diameter, both in the model and anatomical data. In the model, changes in plant water status were identified as the main driver of the IADFs through a direct effect on cell volume. The anatomy data also revealed that a trade-off existed between hydraulic safety and hydraulic efficiency. Although a simplified description of cambial physiology is presented, this integrated modelling approach shows potential value for identifying universal patterns of tree-ring growth and anatomical features over a broad climatic gradient. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Embryonic ring closure: Actomyosin rings do the two-step

PubMed Central

2016-01-01

Actomyosin rings drive numerous closure processes, but the mechanisms by which they contract are still poorly understood. In this issue, Xue and Sokac (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201608025) show that actomyosin ring closure during Drosophila melanogaster cellularization uses two steps, only one of which involves Myosin-2. PMID:27799371

Theoretical analysis of polarization-coupled mode splitting in a single microfiber knot-ring resonator

NASA Astrophysics Data System (ADS)

Qiu, Weiqia; Zhou, Junjie; Yu, Jianhui; Xiao, Yi; Lu, Huihui; Guan, Heyuan; Zhong, Yongchun; Zhang, Jun; Chen, Zhe

2016-06-01

We established a theoretical model for a single knot-ring resonator and investigated the transmission spectrum by Jones matrix. The numerical results show that two orthogonal polarization modes of knot-ring, which are originally resonated at the same wavelength, will split into two resonant modes with different wavelengths. The mode splitting is due to the coupling between the two orthogonal polarization modes in the knot-ring when the twisted angle of the twist coupler is not exactly equal to 2mπ (m is an integer). It is also found that the separation of the mode splitting is linearly proportional to the deviation angle δθ with a high correlation coefficient of 99.6% and a slope of 3.17 nm/rad. Furthermore, a transparency phenomenon analogous to coupled-resonator-induced transparency was also predicted by the model. These findings may have potential applications in lasers and sensors.

A nonlinear plasmonic waveguide based all-optical bidirectional switching

NASA Astrophysics Data System (ADS)

Bana, Xiaoqiang; Pang, Xingxing; Li, Xiaohui; Hu, Bin; Guo, Yixuan; Zheng, Hairong

2018-01-01

In this paper, an all-optical switching with a nanometer coupled ring resonator is demonstrated based on the nonlinear material. By adjusting the light intensity, we implement the resonance wavelength from 880 nm to 940 nm in the nonlinear material structure monocyclic. In the bidirectional switch structure, the center wavelength (i.e. 880 nm) is fixed. By changing the light intensity from I = 0 to I = 53 . 1 MW /cm2, the function of optical switching can be obtained. The results demonstrate that both the single-ring cavity and the T-shaped double-ring structure can realize the optical switching effect. This work takes advantage of the simple structure. The single-ring cavity plasmonic switches have many advantages, such as nanoscale size, low pumping light intensity, ultrafast response time (femtosecond level), etc. It is expected that the proposed all-optical integrated devices can be potentially applied in optical communication, signal processing, and signal sensing, etc.

Vascular tissue engineering by computer-aided laser micromachining.

PubMed

Doraiswamy, Anand; Narayan, Roger J

2010-04-28

Many conventional technologies for fabricating tissue engineering scaffolds are not suitable for fabricating scaffolds with patient-specific attributes. For example, many conventional technologies for fabricating tissue engineering scaffolds do not provide control over overall scaffold geometry or over cell position within the scaffold. In this study, the use of computer-aided laser micromachining to create scaffolds for vascular tissue networks was investigated. Computer-aided laser micromachining was used to construct patterned surfaces in agarose or in silicon, which were used for differential adherence and growth of cells into vascular tissue networks. Concentric three-ring structures were fabricated on agarose hydrogel substrates, in which the inner ring contained human aortic endothelial cells, the middle ring contained HA587 human elastin and the outer ring contained human aortic vascular smooth muscle cells. Basement membrane matrix containing vascular endothelial growth factor and heparin was to promote proliferation of human aortic endothelial cells within the vascular tissue networks. Computer-aided laser micromachining provides a unique approach to fabricate small-diameter blood vessels for bypass surgery as well as other artificial tissues with complex geometries.

Resveratrol and para-coumarate serve as ring precursors for coenzyme Q biosynthesis[S

PubMed Central

Xie, Letian X.; Williams, Kevin J.; He, Cuiwen H.; Weng, Emily; Khong, San; Rose, Tristan E.; Kwon, Ohyun; Bensinger, Steven J.; Marbois, Beth N.; Clarke, Catherine F.

2015-01-01

Coenzyme Q (Q or ubiquinone) is a redox-active polyisoprenylated benzoquinone lipid essential for electron and proton transport in the mitochondrial respiratory chain. The aromatic ring 4-hydroxybenzoic acid (4HB) is commonly depicted as the sole aromatic ring precursor in Q biosynthesis despite the recent finding that para-aminobenzoic acid (pABA) also serves as a ring precursor in Saccharomyces cerevisiae Q biosynthesis. In this study, we employed aromatic 13C6-ring-labeled compounds including 13C6-4HB, 13C6-pABA, 13C6-resveratrol, and 13C6-coumarate to investigate the role of these small molecules as aromatic ring precursors in Q biosynthesis in Escherichia coli, S. cerevisiae, and human and mouse cells. In contrast to S. cerevisiae, neither E. coli nor the mammalian cells tested were able to form 13C6-Q when cultured in the presence of 13C6-pABA. However, E. coli cells treated with 13C6-pABA generated 13C6-ring-labeled forms of 3-octaprenyl-4-aminobenzoic acid, 2-octaprenyl-aniline, and 3-octaprenyl-2-aminophenol, suggesting UbiA, UbiD, UbiX, and UbiI are capable of using pABA or pABA-derived intermediates as substrates. E. coli, S. cerevisiae, and human and mouse cells cultured in the presence of 13C6-resveratrol or 13C6-coumarate were able to synthesize 13C6-Q. Future evaluation of the physiological and pharmacological responses to dietary polyphenols should consider their metabolism to Q. PMID:25681964

Switchable multi-wavelength fiber ring laser based on a compact in-fiber Mach-Zehnder interferometer with photonic crystal fiber

NASA Astrophysics Data System (ADS)

Chen, W. G.; Lou, S. Q.; Feng, S. C.; Wang, L. W.; Li, H. L.; Guo, T. Y.; Jian, S. S.

2009-11-01

Switchable multi-wavelength fiber ring laser with an in-fiber Mach-Zehnder interferometer incorporated into the ring cavity serving as wavelength-selective filter at room temperature is demonstrated. The filter is formed by splicing a section of few-mode photonic crystal fiber (PCF) and two segments of single mode fiber (SMF) with the air-holes on the both sides of PCF intentionally collapsed in the vicinity of the splices. By adjusting the states of the polarization controller (PC) appropriately, the laser can be switched among the stable single-, dual- and triple-wavelength lasing operations by exploiting polarization hole burning (PHB) effect.

Single-Frequency Nd:YAG Ring Lasers with Corner Cube Prism

NASA Astrophysics Data System (ADS)

Wu, Ke-Ying; Yang, Su-Hui; Zhao, Chang-Ming; Wei, Guang-Hui

2000-10-01

We put forward another form of the non-planar ring lasers, in which the corner cube prism is the key element and the Nd:YAG crystal is used as a Porro prism to enclose the ring resonator. The phase shift due to the total internal reflections of the three differently orientated reflection planes of the corner cube prism, Faraday rotation in the Nd:YAG crystal placed in a magnetic field and the different output coupling in S and P polarization form an optical diode and enforce the single-frequency generating power. A round trip analysis of the polarization properties of the resonator is made by the evaluation of Jones matrix.

Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe3O4 nanoparticle rings.

PubMed

Takeno, Yumu; Murakami, Yasukazu; Sato, Takeshi; Tanigaki, Toshiaki; Park, Hyun Soon; Shindo, Daisuke; Ferguson, R Matthew; Krishnan, Kannan M

2014-11-03

This study reports on the correlation between crystal orientation and magnetic flux distribution of Fe 3 O 4 nanoparticles in the form of self-assembled rings. High-resolution transmission electron microscopy demonstrated that the nanoparticles were single-crystalline, highly monodispersed, (25 nm average diameter), and showed no appreciable lattice imperfections such as twins or stacking faults. Electron holography studies of these superparamagnetic nanoparticle rings indicated significant fluctuations in the magnetic flux lines, consistent with variations in the magnetocrystalline anisotropy of the nanoparticles. The observations provide useful information for a deeper understanding of the micromagnetics of ultrasmall nanoparticles, where the magnetic dipolar interaction competes with the magnetic anisotropy.

Nuclear apoptotic volume decrease in individual cells: Confocal microscopy imaging and kinetic modeling.

PubMed

Khalo, Irina V; Konokhova, Anastasiya I; Orlova, Darya Y; Trusov, Konstantin V; Yurkin, Maxim A; Bartova, Eva; Kozubek, Stanislav; Maltsev, Valeri P; Chernyshev, Andrei V

2018-05-30

The dynamics of nuclear morphology changes during apoptosis remains poorly investigated and understood. Using 3D time-lapse confocal microscopy we performed a study of early-stage apoptotic nuclear morphological changes induced by etoposide in single living HepG2 cells. These observations provide a definitive evidence that nuclear apoptotic volume decrease (AVD) is occurring simultaneously with peripheral chromatin condensation (so called "apoptotic ring"). In order to describe quantitatively the dynamics of nuclear morphological changes in the early stage of apoptosis we suggest a general molecular kinetic model, which fits well the obtained experimental data in our study. Results of this work may clarify molecular mechanisms of nuclear morphology changes during apoptosis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Pathogenic Chlamydia Lack a Classical Sacculus but Synthesize a Narrow, Mid-cell Peptidoglycan Ring, Regulated by MreB, for Cell Division

PubMed Central

Packiam, Mathanraj; Hsu, Yen-Pang; Tekkam, Srinivas; Hall, Edward; Rittichier, Jonathan T.; VanNieuwenhze, Michael; Brun, Yves V.; Maurelli, Anthony T.

2016-01-01

The peptidoglycan (PG) cell wall is a peptide cross-linked glycan polymer essential for bacterial division and maintenance of cell shape and hydrostatic pressure. Bacteria in the Chlamydiales were long thought to lack PG until recent advances in PG labeling technologies revealed the presence of this critical cell wall component in Chlamydia trachomatis. In this study, we utilize bio-orthogonal D-amino acid dipeptide probes combined with super-resolution microscopy to demonstrate that four pathogenic Chlamydiae species each possess a ≤ 140 nm wide PG ring limited to the division plane during the replicative phase of their developmental cycles. Assembly of this PG ring is rapid, processive, and linked to the bacterial actin-like protein, MreB. Both MreB polymerization and PG biosynthesis occur only in the intracellular form of pathogenic Chlamydia and are required for cell enlargement, division, and transition between the microbe’s developmental forms. Our kinetic, molecular, and biochemical analyses suggest that the development of this limited, transient, PG ring structure is the result of pathoadaptation by Chlamydia to an intracellular niche within its vertebrate host. PMID:27144308

Pathogenic Chlamydia Lack a Classical Sacculus but Synthesize a Narrow, Mid-cell Peptidoglycan Ring, Regulated by MreB, for Cell Division.

PubMed

Liechti, George; Kuru, Erkin; Packiam, Mathanraj; Hsu, Yen-Pang; Tekkam, Srinivas; Hall, Edward; Rittichier, Jonathan T; VanNieuwenhze, Michael; Brun, Yves V; Maurelli, Anthony T

2016-05-01

The peptidoglycan (PG) cell wall is a peptide cross-linked glycan polymer essential for bacterial division and maintenance of cell shape and hydrostatic pressure. Bacteria in the Chlamydiales were long thought to lack PG until recent advances in PG labeling technologies revealed the presence of this critical cell wall component in Chlamydia trachomatis. In this study, we utilize bio-orthogonal D-amino acid dipeptide probes combined with super-resolution microscopy to demonstrate that four pathogenic Chlamydiae species each possess a ≤ 140 nm wide PG ring limited to the division plane during the replicative phase of their developmental cycles. Assembly of this PG ring is rapid, processive, and linked to the bacterial actin-like protein, MreB. Both MreB polymerization and PG biosynthesis occur only in the intracellular form of pathogenic Chlamydia and are required for cell enlargement, division, and transition between the microbe's developmental forms. Our kinetic, molecular, and biochemical analyses suggest that the development of this limited, transient, PG ring structure is the result of pathoadaptation by Chlamydia to an intracellular niche within its vertebrate host.

Two dynamin-like proteins stabilize FtsZ rings during Streptomyces sporulation.

PubMed

Schlimpert, Susan; Wasserstrom, Sebastian; Chandra, Govind; Bibb, Maureen J; Findlay, Kim C; Flärdh, Klas; Buttner, Mark J

2017-07-25

During sporulation, the filamentous bacteria Streptomyces undergo a massive cell division event in which the synthesis of ladders of sporulation septa convert multigenomic hyphae into chains of unigenomic spores. This process requires cytokinetic Z-rings formed by the bacterial tubulin homolog FtsZ, and the stabilization of the newly formed Z-rings is crucial for completion of septum synthesis. Here we show that two dynamin-like proteins, DynA and DynB, play critical roles in this process. Dynamins are a family of large, multidomain GTPases involved in key cellular processes in eukaryotes, including vesicle trafficking and organelle division. Many bacterial genomes encode dynamin-like proteins, but the biological function of these proteins has remained largely enigmatic. Using a cell biological approach, we show that the two Streptomyces dynamins specifically localize to sporulation septa in an FtsZ-dependent manner. Moreover, dynamin mutants have a cell division defect due to the decreased stability of sporulation-specific Z-rings, as demonstrated by kymographs derived from time-lapse images of FtsZ ladder formation. This defect causes the premature disassembly of individual Z-rings, leading to the frequent abortion of septum synthesis, which in turn results in the production of long spore-like compartments with multiple chromosomes. Two-hybrid analysis revealed that the dynamins are part of the cell division machinery and that they mediate their effects on Z-ring stability during developmentally controlled cell division via a network of protein-protein interactions involving DynA, DynB, FtsZ, SepF, SepF2, and the FtsZ-positioning protein SsgB.

Design and use of a folded four-ring double-tuned birdcage coil for rat brain sodium imaging at 9.4 T.

PubMed

Ha, YongHyun; Choi, Chang-Hoon; Worthoff, Wieland A; Shymanskaya, Aliaksandra; Schöneck, Michael; Willuweit, Antje; Felder, Jörg; Shah, N Jon

2018-01-01

A folded four-ring quadrature birdcage coil was designed and constructed with a double-tune configuration of an outer high-pass coil for 1 H (400 MHz) and inner low-pass coil for 23 Na (105.72 MHz at 9.4 T). The coil was evaluated on the bench and in the scanner, comparing its performance with that of single-tuned coils and a large four-ring coil. All coils were tuned and matched and the isolation between two quadrature ports was found to be better than -13.7 dB for 1 H and -27 dB for 23 Na. Signal-to-noise ratios (SNRs) were calculated and 23 Na flip angle maps were acquired. 23 Na SNR of the folded four-ring reached ∼93% of that obtained with the single-tuned coil. A set of in vivo 1 H and 23 Na axial images to cover the whole rat brain were obtained. The performance of the folded four-ring coil and its benefit for 23 Na imaging experiments have been demonstrated. This proposed four-ring coil could avoid length restrictions, e.g. the shoulders, by folding the outer rings vertically. This facilitates the construction of double-tuned four-ring birdcage coils just to fit the head, leading to higher filling factors and better SNR. Copyright © 2017 Elsevier Inc. All rights reserved.

Cytoskeleton-dependent transport of cytoplasmic particles in previtellogenic to mid-vitellogenic ovarian follicles of Drosophila: time-lapse analysis using video-enhanced contrast microscopy.

PubMed

Bohrmann, J; Biber, K

1994-04-01

In Drosophila oogenesis, several morphogenetic determinants and other developmental factors synthesized in the nurse cells have been shown to accumulate in the oocyte during pre- to mid-vitellogenic stages. However, the mechanisms of the involved intercellular transport processes that seem to be rather selective have not been revealed so far. We have investigated in vitro, by means of video-enhanced contrast time-lapse microscopy, the transport of cytoplasmic particles from the nurse cells through ring canals into the oocyte during oogenesis stages 6-10A. At stage 7, we first observed single particles moving into the previtellogenic oocyte. The particle transfer was strictly unidirectional and seemed to be selective, since only some individual particles moved whereas other particles lying in the vicinity of the ring canals were not transported. The observed transport processes were inhibitable with 2,4-dinitrophenol, cytochalasin B or N-ethylmaleimide, but not with microtubule inhibitors. At the beginning of vitellogenesis (stage 8), the selective translocation of particles through the ring canals became faster (up to 130 nm/second) and more frequent (about 1 particle/minute), whereas during mid-vitellogenesis (stages 9-10A) the velocity and the frequency of particle transport decreased again. Following their more or less rectilinear passage through the ring canals, the particles joined a circular stream of cytoplasmic particles in the oocyte. This ooplasmic particle streaming started at stage 6/7 with velocities of about 80 nm/second and some reversals of direction at the beginning. The particle stream in the oocyte was sensitive to colchicine and vinblastine, but not to cytochalasin B, and we presume that it reflects the rearrangement of ooplasmic microtubules described recently by other authors. We propose that during stages 7-10A, a selective transport of particles into the oocyte occurs through the ring canal along a polarized scaffold of cytoskeletal elements in which microfilaments are involved. This transport might be driven by a myosin-like motor molecule. Either attached to, or organized into, such larger particles or organelles, specific mRNAs and proteins might become selectively transported into the oocyte.

Secondary signet-ring cell adenocarcinoma of urinary bladder from a gastric primary

PubMed Central

Sharma, Pramod K.; Vijay, Mukesh K.; Das, Ranjit K.; Chatterjee, Uttara

2011-01-01

Primary bladder tumor is a frequent urological malignancy, whereas the incidence of secondary bladder tumor from a distant organ is quite rare. Secondary bladder neoplasms represent 1% of all malignant bladder tumors, of which distant metastases from stomach account for about 4% of cases. We present the case of a 30-year-old male who underwent partial gastrectomy for Signet-ring cell carcinoma of the stomach and presented 2 years later with hematuria. On computerized tomography scan, a bladder tumor was found which was resected cystoscopically. The histopathological examination revealed secondary Signet-ring cell adenocarcinoma of the urinary bladder. PMID:21747602

Ring resonant cavities for spectroscopy

DOEpatents

Zare, R.N.; Martin, J.; Paldus, B.A.; Xie, J.

1999-06-15

Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS). 6 figs.

Ring resonant cavities for spectroscopy

DOEpatents

Zare, Richard N.; Martin, Juergen; Paldus, Barbara A.; Xie, Jinchun

1999-01-01

Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS).

The role of cytokeratins 20 and 7 and estrogen receptor analysis in separation of metastatic lobular carcinoma of the breast and metastatic signet ring cell carcinoma of the gastrointestinal tract.

PubMed

Tot, T

2000-06-01

Metastatic signet ring cell carcinomas of unknown primary site can represent a clinical problem. Gastrointestinal signet ring cell carcinomas and invasive lobular carcinomas of the breast are the most common sources of these metastases. Immunohistochemical algorithms have been successfully used in the search for the unknown primary adenocarcinomas. In the present study a series of primary invasive lobular breast carcinomas (79 cases) and their metastases and a series of gastrointestinal signet ring cell carcinomas (22 primary and 13 metastases) were stained with monoclonal antibodies for cytokeratin (CK) 20 and CK7 and for estrogen receptors (ER). The staining was evaluated as negative (no staining), focally (less than 10% of the tumor cells stained) or diffusely positive. All the primary and metastatic gastrointestinal signet ring cell carcinomas proved to be CK20 positive, while only 2/79 (3%) of the primary and 1/21 metastatic lobular carcinomas (5%) stained positively for this CK. None of the gastrointestinal carcinomas and the majority of the lobular carcinomas expressed ER. The majority of the tumors were CK7+. Using CK20 alone, 33 of 34 metastases could be properly classified as gastrointestinal (CK20+) or mammary (CK20-). ER identified 31/34 of breast cancer metastases. By combining the results of CK20 and ER staining all the metastases could be properly classified as the CK20+/ER- pattern identified all the gastrointestinal tumors.

SOI ring resonators with controllable MMI coupler sections

NASA Astrophysics Data System (ADS)

Hu, Youfang; Gardes, Frédéric Y.; Mashanovich, Goran Z.; Reed, Graham T.

2011-01-01

A ring resonator using a single 2×2 MMI as the coupler section has the distinct advantages of low sensitivity to fabrication error, temperature, wavelength and polarisation. However, the coupling coefficient of the 2×2 MMI coupler is fixed; hence, the performance of this type of device is limited, e.g. transmission spectrum with high extinction ratio is difficult to achieve. We have designed and simulated ring resonators with coupler sections consisting of two 2×2 MMIs and phase shifters, so that the coupling efficiency can be varied from 0% to 100% with relative ease. For a single ring resonator, the transmission spectrum can be controlled to achieve an extinction ratio of >20dB and a spectral bandwidth of <1nm. For a multiple ring filter, the transmission spectrum can be controlled to achieve an extinction ratio of >30dB and a bandwidth of <1nm in addition, a flat-top transmission spectrum is also achievable. The whole device has a footprint of approximately 200μm by 100μm.

Hybrid optical fiber add-drop filter based on wavelength dependent light coupling between micro/nano fiber ring and side-polished fiber

PubMed Central

Yu, Jianhui; Jin, Shaoshen; Wei, Qingsong; Zang, Zhigang; Lu, Huihui; He, Xiaoli; Luo, Yunhan; Tang, Jieyuan; Zhang, Jun; Chen, Zhe

2015-01-01

In this paper, we report our experimental study on directly coupling a micro/nano fiber (MNOF) ring with a side-polished fiber(SPF). As a result of the study, the behavior of an add-drop filter was observed. The demonstrated add-drop filter explored the wavelength dependence of light coupling between a MNOF ring and a SPF. The characteristics of the filter and its performance dependence on the MNOF ring diameter were investigated experimentally. The investigation resulted in an empirically obtained ring diameter that showed relatively good filter performance. Since light coupling between a (MNOF) and a conventional single mode fiber has remained a challenge in the photonic integration community, the present study may provide an alternative way to couple light between a MNOF device and a conventional single mode fiber based device or system. The hybridization approach that uses a SPF as a platform to integrate a MNOF device may enable the realization of other all-fiber optical hybrid devices. PMID:25578467

Direct laser writing of polymer micro-ring resonator ultrasonic sensors

NASA Astrophysics Data System (ADS)

Wei, Heming; Krishnaswamy, Sridhar

2017-04-01

With the development of photoacoustic technology in recent years, ultrasound-related sensors play a vital role in a number of areas ranging from scientific research to nondestructive testing. Compared with the traditional PZT transducer as ultrasonic sensors, novel ultrasonic sensors based on optical methods such as micro-ring resonators have gained increasing attention. The total internal reflection of the light along the cavity results in light propagating in microcavities as whispering gallery modes (WGMs), which are extremely sensitive to change in the radius and refractive index of the cavity induced by ultrasound strain field. In this work, we present a polymer optical micro-ring resonator based ultrasonic sensor fabricated by direct laser writing optical lithography. The design consists of a single micro-ring and a straight tapered waveguide that can be directly coupled by single mode fibers (SMFs). The design and fabrication of the printed polymer resonator have been optimized to provide broad bandwidth and high optical quality factor to ensure high detection sensitivity. The experiments demonstrate the potential of the polymer micro-ring resonator to works as a high-performance ultrasonic sensor.

Quasi-one-dimensional density of states in a single quantum ring.

PubMed

Kim, Heedae; Lee, Woojin; Park, Seongho; Kyhm, Kwangseuk; Je, Koochul; Taylor, Robert A; Nogues, Gilles; Dang, Le Si; Song, Jin Dong

2017-01-05

Generally confinement size is considered to determine the dimensionality of nanostructures. While the exciton Bohr radius is used as a criterion to define either weak or strong confinement in optical experiments, the binding energy of confined excitons is difficult to measure experimentally. One alternative is to use the temperature dependence of the radiative recombination time, which has been employed previously in quantum wells and quantum wires. A one-dimensional loop structure is often assumed to model quantum rings, but this approximation ceases to be valid when the rim width becomes comparable to the ring radius. We have evaluated the density of states in a single quantum ring by measuring the temperature dependence of the radiative recombination of excitons, where the photoluminescence decay time as a function of temperature was calibrated by using the low temperature integrated intensity and linewidth. We conclude that the quasi-continuous finely-spaced levels arising from the rotation energy give rise to a quasi-one-dimensional density of states, as long as the confined exciton is allowed to rotate around the opening of the anisotropic ring structure, which has a finite rim width.

Ring-like distribution of constitutive heterochromatin in bovine senescent cells.

PubMed

Pichugin, Andrey; Beaujean, Nathalie; Vignon, Xavier; Vassetzky, Yegor

2011-01-01

Cells that reach "Hayflick limit" of proliferation, known as senescent cells, possess a particular type of nuclear architecture. Human senescent cells are characterized by the presence of highly condensed senescent associated heterochromatin foci (SAHF) that can be detected both by immunostaining for histone H3 three-methylated at lysine 9 (H3K9me3) and by DAPI counterstaining. We have studied nuclear architecture in bovine senescent cells using a combination of immunofluorescence and 3D fluorescent in-situ hybridization (FISH). Analysis of heterochromatin distribution in bovine senescent cells using fluorescent in situ hybridization for pericentric chromosomal regions, immunostaining of H3K9me3, centromeric proteins CENP A/B and DNA methylation showed a lower level of heterochromatin condensation as compared to young cells. No SAHF foci were observed. Instead, we observed fibrous ring-like or ribbon-like heterochromatin patterns that were undetectable with DAPI counterstaining. These heterochromatin fibers were associated with nucleoli. Constitutive heterochromatin in bovine senescent cells is organized in ring-like structures.

Cortical PAR polarity proteins promote robust cytokinesis during asymmetric cell division

PubMed Central

Jordan, Shawn N.; Davies, Tim; Zhuravlev, Yelena; Dumont, Julien; Shirasu-Hiza, Mimi

2016-01-01

Cytokinesis, the physical division of one cell into two, is thought to be fundamentally similar in most animal cell divisions and driven by the constriction of a contractile ring positioned and controlled solely by the mitotic spindle. During asymmetric cell divisions, the core polarity machinery (partitioning defective [PAR] proteins) controls the unequal inheritance of key cell fate determinants. Here, we show that in asymmetrically dividing Caenorhabditis elegans embryos, the cortical PAR proteins (including the small guanosine triphosphatase CDC-42) have an active role in regulating recruitment of a critical component of the contractile ring, filamentous actin (F-actin). We found that the cortical PAR proteins are required for the retention of anillin and septin in the anterior pole, which are cytokinesis proteins that our genetic data suggest act as inhibitors of F-actin at the contractile ring. Collectively, our results suggest that the cortical PAR proteins coordinate the establishment of cell polarity with the physical process of cytokinesis during asymmetric cell division to ensure the fidelity of daughter cell formation. PMID:26728855

Design study for a liquid metal slip ring solar array orientation mechanism

NASA Technical Reports Server (NTRS)

Clark, R. B.

1972-01-01

The design of a single axis orientation mechanism for solar arrays on high power synchronous satellites is studied primarily with respect to providing 116 liquid metal slip rings for reduced friction and improved electrical characteristics. Designs and tradeoff studies for the slip rings and other components are presented. An assembly containing 33 slip rings of three design approaches was designed, fabricated, and vacuum tested to 30 amperes and 30,000 volts. Containment of the liquid metal gallium in large diameter slip rings was difficult. A design approach is presented which is expected to provide improved retention of the liquid metal.

Mechanical seal having a double-tier mating ring

DOEpatents

Khonsari, Michael M.; Somanchi, Anoop K.

2005-09-13

An apparatus and method to enhance the overall performance of mechanical seals in one of the following ways: by reducing seal face wear, by reducing the contact surface temperature, or by increasing the life span of mechanical seals. The apparatus is a mechanical seal (e.g., single mechanical seals, double mechanical seals, tandem mechanical seals, bellows, pusher mechanical seals, and all types of rotating and reciprocating machines) comprising a rotating ring and a double-tier mating ring. In a preferred embodiment, the double-tier mating ring comprises a first and a second stationary ring that together form an agitation-inducing, guided flow channel to allow for the removal of heat generated at the seal face of the mating ring by channeling a coolant entering the mating ring to a position adjacent to and in close proximity with the interior surface area of the seal face of the mating ring.

Experimental observation of intraocular pressure changes during microkeratome suctioning in laser in situ keratomileusis.

PubMed

Bissen-Miyajima, Hiroko; Suzuki, Shintaro; Ohashi, Yoshie; Minami, Keiichiro

2005-03-01

To observe changes in intraocular pressure (IOP), the manner in which the eye is suctioned, and the effect of the number of suction ports. Department of Ophthalmology, Tokyo Dental College, Suidobashi Hospital, Tokyo, Japan. Suction rings with single or dual ports were made of transparent acrylic acid resin to facilitate observation with a digital video camera. The IOP and the duration of the IOP increase (time to reach 90% of the maximum IOP) were measured in 6 porcine eyes with an intra-vein pressure-sensor catheter in the vitreous cavity. The IOP changes were recorded using a personal computer. Suctioning with single- and dual-port suction rings was similar. The IOP increases with single- and dual-port suction rings were similar (99.1 mm Hg +/- 6.1 [SD] and 99.0 +/- 6.5 mm Hg, respectively) (P=.987). The duration of the IOP increase was also similar (4.21 +/- 0.24 seconds and 4.12 +/- 0.33 seconds, respectively) (P=.190). The number of ports did not affect suctioning and changes in IOP. This technique is useful in developing the ideal shape and setting of the suction ring.

A node organization in the actomyosin contractile ring generates tension and aids stability.

PubMed

Thiyagarajan, Sathish; Wang, Shuyuan; O'Shaughnessy, Ben

2017-11-07

During cytokinesis, a contractile actomyosin ring constricts and divides the cell in two. How the ring marshals actomyosin forces to generate tension is not settled. Recently, a superresolution microscopy study of the fission yeast ring revealed that myosins and formins that nucleate actin filaments colocalize in plasma membrane-anchored complexes called nodes in the constricting ring. The nodes move bidirectionally around the ring. Here we construct and analyze a coarse-grained mathematical model of the fission yeast ring to explore essential consequences of the recently discovered ring ultrastructure. The model reproduces experimentally measured values of ring tension, explains why nodes move bidirectionally, and shows that tension is generated by myosin pulling on barbed-end-anchored actin filaments in a stochastic sliding-filament mechanism. This mechanism is not based on an ordered sarcomeric organization. We show that the ring is vulnerable to intrinsic contractile instabilities, and protection from these instabilities and organizational homeostasis require both component turnover and anchoring of components to the plasma membrane. © 2017 Thiyagarajan, Wang, and O’Shaughnessy. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Some physiologic blood values of wild diving ducks

USGS Publications Warehouse

Kocan, R.M.

1972-01-01

Blood samples were obtained from 54 canvasbacks (Aythya valisineria), 30 lesser scaup (A. affinis), 3 ring-necks (A. collaris), and 3 buffleheads (Bucephala albeola), which were wintering on Chesapeake Bay. These blood samples were used for: red blood cell counts (cans. 2.56 x 106/mm3; scaup 2.45 x 106/mm3; ring-necks 2.50 x 106mm3; buffiehead 2.64 x lO6/mm3), packed cell volume (cans. 52.2%; scaup 57.1%; ring-neck 49.1%; buffieheads 54.3%), total protein (cans. 4.4 g/100 ml; scaup 4.4 g/100 mi; ring-neck 3.5 g/100 ml; buffiehead 3.8 g/100 ml), erythrocyte measurements, and electrophoretic analysis of plasma and serum. Variations between individuals of the same species and sex were slight but a possible difference between male and female erythrocyte numbers and packed cell volumes was evident in the canvasback and scaup samples.

Mass production of shaped particles through vortex ring freezing

NASA Astrophysics Data System (ADS)

An, Duo; Warning, Alex; Yancey, Kenneth G.; Chang, Chun-Ti; Kern, Vanessa R.; Datta, Ashim K.; Steen, Paul H.; Luo, Dan; Ma, Minglin

2016-08-01

A vortex ring is a torus-shaped fluidic vortex. During its formation, the fluid experiences a rich variety of intriguing geometrical intermediates from spherical to toroidal. Here we show that these constantly changing intermediates can be `frozen' at controlled time points into particles with various unusual and unprecedented shapes. These novel vortex ring-derived particles, are mass-produced by employing a simple and inexpensive electrospraying technique, with their sizes well controlled from hundreds of microns to millimetres. Guided further by theoretical analyses and a laminar multiphase fluid flow simulation, we show that this freezing approach is applicable to a broad range of materials from organic polysaccharides to inorganic nanoparticles. We demonstrate the unique advantages of these vortex ring-derived particles in several applications including cell encapsulation, three-dimensional cell culture, and cell-free protein production. Moreover, compartmentalization and ordered-structures composed of these novel particles are all achieved, creating opportunities to engineer more sophisticated hierarchical materials.

Breast Metastatic Localization of Signet-Ring Cell Gastric Carcinoma

PubMed Central

Parrell Soler, C.; Palacios Marqués, A.; Saco López, L.; Bermejo De las Heras, R.; Pertusa Martínez, S.

2011-01-01

Metastatic tumors in the breast are quite rare and constitute 0,5 to 6% of all breast malignancies. They often occur in a polymetastatic context. Gastrointestinal lesions rarely metastasize to the breast. The first case of a metastasis deposit to the breast and ovary from gastric signet-ring cell carcinoma was reported in the literature in 1999. Since this report, only 5 cases have been reported. We present a case report of a 37-year-old woman who complained of a lump in the left breast. Two months earlier, the woman underwent a subtotal gastrectomy and a total hysterectomy with double anexectomy, which histologically was diagnosed of gastric signet-ring carcinoma, disseminated with Krukenberg's tumor. In those days, the patient was following a chemotherapy treatment. A core needle biopsy of the lesion in left breast revealed cells with signet-ring features, with probably gastric origin. PMID:21637360

Self-assembly of single "square" quantum rings in gold-free GaAs nanowires.

PubMed

Zha, Guowei; Shang, Xiangjun; Su, Dan; Yu, Ying; Wei, Bin; Wang, Li; Li, Mifeng; Wang, Lijuan; Xu, Jianxing; Ni, Haiqiao; Ji, Yuan; Sun, Baoquan; Niu, Zhichuan

2014-03-21

Single nanostructures embedded within nanowires (NWs) represent one of the most promising technologies for applications in quantum photonics. However, fabrication imperfections and etching-induced defects are inevitable for top-down fabrications, whereas self-assembly bottom-up approaches cannot avoid the difficulties of its stochastic nature and are limited to restricted heterogeneous material systems. Here we demonstrate the versatile self-assembly of single "square" quantum rings (QR) on the sidewalls of gold-free GaAs NWs for the first time. By tuning the deposition temperature, As overpressure and amount of gallium-droplets, we were able to control the density and morphology of the structure, yielding novel single quantum dots, QR, coupled QRs, and nano-antidots. A proposed model based on a strain-driven, transport-dependent nucleation of gallium droplets at high temperature accounts for the formation mechanism of these structures. We achieved a single-QR-in-NW structure, of which the optical properties were analyzed using micro-photoluminescence at 10 K and a spatially resolved cathodoluminescence technique at 77 K. The spectra show sharp discrete peaks; of these peaks, the narrowest linewidth (separation) was 578 μeV (1-3 meV), reflecting the quantized nature of the ring-type electronic states.

Conditioning of BPM pickup signals for operations of the Duke storage ring with a wide range of single-bunch current

NASA Astrophysics Data System (ADS)

Xu, Wei; Li, Jing-Yi; Huang, Sen-Lin; Z. Wu, W.; Hao, H.; P., Wang; K. Wu, Y.

2014-10-01

The Duke storage ring is a dedicated driver for the storage ring based oscillator free-electron lasers (FELs), and the High Intensity Gamma-ray Source (HIGS). It is operated with a beam current ranging from about 1 mA to 100 mA per bunch for various operations and accelerator physics studies. High performance operations of the FEL and γ-ray source require a stable electron beam orbit, which has been realized by the global orbit feedback system. As a critical part of the orbit feedback system, the electron beam position monitors (BPMs) are required to be able to precisely measure the electron beam orbit in a wide range of the single-bunch current. However, the high peak voltage of the BPM pickups associated with high single-bunch current degrades the performance of the BPM electronics, and can potentially damage the BPM electronics. A signal conditioning method using low pass filters is developed to reduce the peak voltage to protect the BPM electronics, and to make the BPMs capable of working with a wide range of single-bunch current. Simulations and electron beam based tests are performed. The results show that the Duke storage ring BPM system is capable of providing precise orbit measurements to ensure highly stable FEL and HIGS operations.

The rotating spectrometer: Biotechnology for cell separations

NASA Technical Reports Server (NTRS)

Noever, David A.

1991-01-01

An instrument for biochemical studies, called the rotating spectrometer, separates previously inseparable cell cultures. The rotating spectrometer is intended for use in pharmacological studies which require fractional splitting of heterogeneous cell cultures based on cell morphology and swimming behavior. As a method to separate and concentrate cells in free solution, the rotating method requires active organism participation and can effectively split the large class of organisms known to form spontaneous patterns. Examples include the biochemical star, an organism called Tetrahymena pyriformis. Following focusing in a rotating frame, the separation is accomplished using different radial dependencies of concentrated algal and protozoan species. The focusing itself appears as concentric rings and arises from the coupling between swimming direction and Coriolis forces. A dense cut is taken at varying radii, and extraction is replenished at an inlet. Unlike standard separation and concentrating techniques such as filtration or centrifugation, the instrument is able to separate motile from immotile fractions. For a single pass, typical split efficiencies can reach 200 to 300 percent compared to the inlet concentration.

The rotating spectrometer: New biotechnology for cell separations

NASA Technical Reports Server (NTRS)

Noever, David A.; Matsos, Helen C.

1990-01-01

An instrument for biochemical studies, called the rotating spectrometer, separates previously inseparable cell cultures. The rotating spectrometer is intended for use in pharmacological studies which require fractional splitting of heterogeneous cell cultures based on cell morphology and swimming behavior. As a method to separate and concentrate cells in free solution, the rotating method requires active organism participation and can effectively split the large class of organisms known to form spontaneous patterns. Examples include the biochemical star, an organism called Tetrahymena pyriformis. Following focusing in a rotated frame, the separation is accomplished using different radial dependencies of concentrated algal and protozoan species. The focusing itself appears as concentric rings and arises from the coupling between swimming direction and Coriolis forces. A dense cut is taken at varying radii and extraction is replenished at an inlet. Unlike standard separation and concentrating techniques such as filtration or centrifugation, the instrument is able to separate motile from immotile fractions. For a single pass, typical split efficiencies can reach 200 to 300 percent compared to the inlet concentration.

The c-ring stoichiometry of ATP synthase is adapted to cell physiological requirements of alkaliphilic Bacillus pseudofirmus OF4

PubMed Central

Preiss, Laura; Klyszejko, Adriana L.; Hicks, David B.; Liu, Jun; Fackelmayer, Oliver J.; Yildiz, Özkan; Krulwich, Terry A.; Meier, Thomas

2013-01-01

The c-rings of ATP synthases consist of individual c-subunits, all of which harbor a conserved motif of repetitive glycine residues (GxGxGxG) important for tight transmembrane α-helix packing. The c-ring stoichiometry determines the number of ions transferred during enzyme operation and has a direct impact on the ion-to-ATP ratio, a cornerstone parameter of cell bioenergetics. In the extreme alkaliphile Bacillus pseudofirmus OF4, the glycine motif is replaced by AxAxAxA. We performed a structural study on two mutants with alanine-to-glycine changes using atomic force microscopy and X-ray crystallography, and found that mutants form smaller c12 rings compared with the WT c13. The molar growth yields of B. pseudofirmus OF4 cells on malate further revealed that the c12 mutants have a considerably reduced capacity to grow on limiting malate at high pH. Our results demonstrate that the mutant ATP synthases with either c12 or c13 can support ATP synthesis, and also underscore the critical importance of an alanine motif with c13 ring stoichiometry for optimal growth at pH >10. The data indicate a direct connection between the precisely adapted ATP synthase c-ring stoichiometry and its ion-to-ATP ratio on cell physiology, and also demonstrate the bioenergetic challenges and evolutionary adaptation strategies of extremophiles. PMID:23613590

CHEMISTRY OF OXIDATION OF POLYCYCLIC AROMATIC HYDROCARBONS BY SOIL PSEUDOMONADS

PubMed Central

Rogoff, Martin H.

1962-01-01

Rogoff, Martin H. (U.S. Bureau of Mines, Pittsburgh, Pa.). Oxidation of polycyclic aromatic hydrocarbons by soil pseudomonads. J. Bacteriol. 83:998–1004. 1962.—Substitution of phenanthrene by a methyl group at the 9-carbon blocks oxidation of the compound by a resting-cell suspension of a phenanthrene-grown soil pseudomonad. When 2-methylphenanthrene is provided, the oxidation rate is considerably higher; 3-methylphenanthrene is oxidized at a rate intermediate between the other two, even though the methyl group is attached to a carbon directly involved in ring splitting. Cells grown on naphthalene or anthracene oxidize phenanthrene at a much lower rate than cells grown with phenanthrene or 2-methylnaphthalene as the source of carbon. Naphthalene-grown cells also absorb less phenanthrene from aqueous solution than do their phenanthrene-grown counterparts. The data are in keeping with the hypothesis that polynuclear aromatic hydrocarbons attach to the relevant bacterial enzymes at carbon-carbon bonds of high electron density (K regions; localized double bonds), and that the ring-splitting reactions then occur at other bonds on the substrate molecule. The actual bond that undergoes fission is determined by the electronic and steric configurations of the enzyme-substrate complex. When linearly arranged aromatic compounds such as naphthalene or anthracene are attacked, attachment to an enzyme and ring splitting may take place on the same ring; angular aromatic compounds such as phenanthrene afford attachment to an enzyme at a bond in a ring other than the one containing the ring-splitting site. PMID:14493381

Vanillin formation from ferulic acid in Vanilla planifolia is catalysed by a single enzyme.

PubMed

Gallage, Nethaji J; Hansen, Esben H; Kannangara, Rubini; Olsen, Carl Erik; Motawia, Mohammed Saddik; Jørgensen, Kirsten; Holme, Inger; Hebelstrup, Kim; Grisoni, Michel; Møller, Birger Lindberg

2014-06-19

Vanillin is a popular and valuable flavour compound. It is the key constituent of the natural vanilla flavour obtained from cured vanilla pods. Here we show that a single hydratase/lyase type enzyme designated vanillin synthase (VpVAN) catalyses direct conversion of ferulic acid and its glucoside into vanillin and its glucoside, respectively. The enzyme shows high sequence similarity to cysteine proteinases and is specific to the substitution pattern at the aromatic ring and does not metabolize caffeic acid and p-coumaric acid as demonstrated by coupled transcription/translation assays. VpVAN localizes to the inner part of the vanilla pod and high transcript levels are found in single cells located a few cell layers from the inner epidermis. Transient expression of VpVAN in tobacco and stable expression in barley in combination with the action of endogenous alcohol dehydrogenases and UDP-glucosyltransferases result in vanillyl alcohol glucoside formation from endogenous ferulic acid. A gene encoding an enzyme showing 71% sequence identity to VpVAN was identified in another vanillin-producing plant species Glechoma hederacea and was also shown to be a vanillin synthase as demonstrated by transient expression in tobacco.

Vanillin formation from ferulic acid in Vanilla planifolia is catalysed by a single enzyme

PubMed Central

Gallage, Nethaji J.; Hansen, Esben H.; Kannangara, Rubini; Olsen, Carl Erik; Motawia, Mohammed Saddik; Jørgensen, Kirsten; Holme, Inger; Hebelstrup, Kim; Grisoni, Michel; Møller, Birger Lindberg

2014-01-01

Vanillin is a popular and valuable flavour compound. It is the key constituent of the natural vanilla flavour obtained from cured vanilla pods. Here we show that a single hydratase/lyase type enzyme designated vanillin synthase (VpVAN) catalyses direct conversion of ferulic acid and its glucoside into vanillin and its glucoside, respectively. The enzyme shows high sequence similarity to cysteine proteinases and is specific to the substitution pattern at the aromatic ring and does not metabolize caffeic acid and p-coumaric acid as demonstrated by coupled transcription/translation assays. VpVAN localizes to the inner part of the vanilla pod and high transcript levels are found in single cells located a few cell layers from the inner epidermis. Transient expression of VpVAN in tobacco and stable expression in barley in combination with the action of endogenous alcohol dehydrogenases and UDP-glucosyltransferases result in vanillyl alcohol glucoside formation from endogenous ferulic acid. A gene encoding an enzyme showing 71% sequence identity to VpVAN was identified in another vanillin-producing plant species Glechoma hederacea and was also shown to be a vanillin synthase as demonstrated by transient expression in tobacco. PMID:24941968

The price of independence: cell separation in fission yeast.

PubMed

Martín-García, Rebeca; Santos, Beatriz

2016-04-01

The ultimate goal of cell division is to give rise to two viable independent daughter cells. A tight spatial and temporal regulation between chromosome segregation and cytokinesis ensures the viability of the daughter cells. Schizosaccharomyces pombe, commonly known as fission yeast, has become a leading model organism for studying essential and conserved mechanisms of the eukaryotic cell division process. Like many other eukaryotic cells it divides by binary fission and the cleavage furrow undergoes ingression due to the contraction of an actomyosin ring. In contrast to mammalian cells, yeasts as cell-walled organisms, also need to form a division septum made of cell wall material to complete the process of cytokinesis. The division septum is deposited behind the constricting ring and it will constitute the new ends of the daughter cells. Cell separation also involves cell wall degradation and this process should be precisely regulated to avoid cell lysis. In this review, we will give a brief overview of the whole cytokinesis process in fission yeast, from the positioning and assembly of the contractile ring to the final step of cell separation, and the problems generated when these processes are not precise.

Tunable semiconductor lasers

NASA Technical Reports Server (NTRS)

Taghavi-Larigani, Shervin (Inventor); Vanzyl, Jakob J. (Inventor); Yariv, Amnon (Inventor)

2006-01-01

Tunable semiconductor lasers are disclosed requiring minimized coupling regions. Multiple laser embodiments employ ring resonators or ring resonator pairs using only a single coupling region with the gain medium are detailed. Tuning can be performed by changing the phase of the coupling coefficient between the gain medium and a ring resonator of the laser. Another embodiment provides a tunable laser including two Mach-Zehnder interferometers in series and a reflector coupled to a gain medium.

Assessment of central corneal thickness and corneal endothelial morphology using ultrasound pachymetry, non-contact specular microscopy, and Confoscan 4 confocal microscopy

PubMed Central

2013-01-01

Background The aim was to compare the repeatability, reproducibility and inherent precision of ultrasound pachymetry (USP), noncontact specular microscopy (SP-2000P) and the Confoscan 4 confocal microscope (z-ring CS4) in measuring endothelial cell density (ECD), coefficient of variation of cell size (CV), and central corneal thickness (CCT) in normal eyes. Methods In this prospective study, one eye was selected from each of 30 subjects for the measurements of ECD, CV and CCT, which were taken by two observers. Results were analyzed statistically by repeated-measures analysis of variance (ANOVA) for intra-observer repeatability, inter-observer reproducibility, unpaired t-test, paired t-test, and Bland–Altman analyses to determine limits of agreement (LOA) between the three instruments. Results Mean ECD, measured by SP-2000P and z-ring CS4, were 3115.50 ± 279.70 cells/mm2 and 3167.50 ± 264.75 cells/mm2, respectively (observer 1), and 3192.63 ± 249.42 cells/mm2 (z-ring, observer 2). Mean CV measurements were 27.12 ± 2.51 and 27.10 ± 2.41 (SP-2000P and z-ring CS4, respectively; observer 1), and 27.17 ± 2.25 (z-ring, observer 2). Mean CCT values were 555.11 ± 35.83 μm (USP), 535.82 ± 41.10 μm (SP-2000P) and 552.57 ± 36.83 μm (z-ring CS4), and 554.97 ± 36.34 μm (z-ring CS4, observer 2). However, pairwise tests in all cases there was good repeatability and reproducibility as shown by inter-observer and intra-observer analysis of variance for each of the instruments. Conclusions The SP-2000P and the z-ring CS4 can be used interchangeably to measure ECD and CV. For CCT, the sample size was too small to test for differences of the CCT measurements between the three instruments. PMID:24274022

Interactive effects of PAHs with different rings and As on their uptake, transportation, and localization in As hyperaccumulator.

PubMed

Liao, Xiaoyong; Wu, Zeying; Ma, Xu; Gong, Xuegang; Yan, Xiulan

2017-11-01

In order to illuminate the mechanism of the interaction of polycyclic aromatic hydrocarbon (PAH) with different benzene rings and arsenic (As) in As hyperaccumulator, Pteris vittata L., the uptakes of PAHs were investigated using hydroponics simulation and localizations of PAHs in the plant were determined using two-photon laser scanning confocal microscopy (TPLSCM). The results showed that the total As concentration in different parts of P. vittata decreased in the presence of PAHs with increased numbers of benzene rings: 38.0-47.4% for benzo(a)pyrene (BaP, five rings), 20.5-35.9% for pyrene (PYR, four rings), and 13.7-16.6% for fluorine (FLU, three rings). BaP and PYR concentrations increased, while FLU concentration decreased in the presence of As. The results of TPLSCM revealed that PAHs distributed in epidermal cells of roots, xylem, and endothelial cells of rachis, epidermis, and stomatal cells of pinnae; however, the fluorescence intensity of BaP and PYR were higher than FLU significantly in plant. This study provided important basis to further research on interactive effects of PAHs and As in the P. vittata. These findings were important to understand the mechanisms of PAH and As translocation and distribution by P. vittata.

Toward a detailed description of the pathways of allosteric communication in the GroEL chaperonin through atomistic simulation.

PubMed

Piggot, Thomas J; Sessions, Richard B; Burston, Steven G

2012-02-28

GroEL, along with its coprotein GroES, is essential for ensuring the correct folding of unfolded or newly synthesized proteins in bacteria. GroEL is a complex, allosteric molecule, composed of two heptameric rings stacked back to back, that undergoes large structural changes during its reaction cycle. These structural changes are driven by the cooperative binding and subsequent hydrolysis of ATP, by GroEL. Despite numerous previous studies, the precise mechanisms of allosteric communication and the associated structural changes remain elusive. In this paper, we describe a series of all-atom, unbiased, molecular dynamics simulations over relatively long (50-100 ns) time scales of a single, isolated GroEL subunit and also a heptameric GroEL ring, in the presence and absence of ATP. Combined with results from a distance restraint-biased simulation of the single ring, the atomistic details of the earliest stages of ATP-driven structural changes within this complex molecule are illuminated. Our results are in broad agreement with previous modeling studies of isolated subunits and with a coarse-grained, forcing simulation of the single ring. These are the first reported all-atom simulations of the GroEL single-ring complex and provide a unique insight into the role of charged residues K80, K277, R284, R285, and E388 at the subunit interface in transmission of the allosteric signal. These simulations also demonstrate the feasibility of performing all-atom simulations of very large systems on sufficiently long time scales on typical high performance computing facilities to show the origins of the earliest events in biologically relevant processes.

The varieties of symmetric stellar rings and radial caustics in galaxy disks

NASA Technical Reports Server (NTRS)

Struck-Marcell, Curtis; Lotan, Pnina

1990-01-01

Numerical, restricted three-body and analytic calculations are used to study the formation and propagation of cylindrically symmetric stellar ring waves in galaxy disks. It is shown that such waves can evolve in a variety of ways, depending on the amplitude of the perturbation and the potential of the target galaxy. Rings can thicken as they propagate outward, remain at a nearly constant width, or be pinched off at large radii. Multiple, closely spaced rings can result from a low-amplitude collision, while an outer ring can appear well-separated from overlapping inner rings or an apparent lens structure in halo-dominated potentials. All the single-encounter rings consist of paired fold caustics. The simple, impulsive, kinematic oscillation equations appear to provide a remarkably accurate model of the numerical simulations. Simple analytic approximations to these equations permit very good estimates of oscillation periods and amplitudes, the evolution of ring widths, and ring birth and propagation characteristics.

Active noise control using noise source having adaptive resonant frequency tuning through stress variation

NASA Technical Reports Server (NTRS)

Pla, Frederic G. (Inventor); Renshaw, Anthony A. (Inventor); Rajiyah, Harindra (Inventor); Hedeen, Robert A. (Inventor)

1995-01-01

A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by an expandable ring embedded in the noise radiating element. Excitation of the ring causes expansion or contraction of the ring, thereby varying the stress in the noise radiating element. The ring is actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the ring, causing the ring to expand or contract. Instead of a single ring embedded in the noise radiating panel, a first expandable ring can be bonded to one side of the noise radiating element, and a second expandable ring can be bonded to the other side.

Assembly interdependence among the S. cerevisiae bud neck ring proteins Elm1p, Hsl1p and Cdc12p.

PubMed

Thomas, Courtney L; Blacketer, Melissa J; Edgington, Nicholas P; Myers, Alan M

2003-07-15

In Saccharomyces cerevisiae, a complex comprising more than 20 different polypeptides assembles in a ring at the neck between the mother cell and the bud. This complex functions to coordinate cell morphology with cell division. Relatively little is known about this control system, including the physical relationships between the components of the neck ring. This study addressed the assembly interactions of three components of the ring, specifically the protein kinases Elm1p and Hsl1p and the septin Cdc12p. Specific amino acid substitutions in each of these three proteins were identified that either cause or suppress a characteristic phenotype of abnormally elongated cells and delay in the G(2)-M transition. Each protein was fused to green fluorescent protein, and its ability to localize at the neck was monitored in vivo in cells of various genotypes. Localization of Hsl1p to the neck requires Elm1p function. Elm1p localized normally in the absence of Hsl1p, although a specific point mutation in Hsl1p clearly affected Elm1p localization. The cdc12-122 mutation prevented assembly of Elm1p or Hsl1p into the neck ring. Normal assembly of Cdc12p at the neck was dependent upon Elm1p and also, to a smaller extent, on Hsl1p. Ectopic localization of Cdc12p at the bud tip was observed frequently in elm1 mutants and also, to a lesser extent, in hsl1 mutants. Thus, Elm1p is a key factor in the assembly and/or maintenance of Hsl1p, as well as at least one septin, into the bud neck ring. Copyright 2003 John Wiley & Sons, Ltd.

Methylocystis strain SB2 materials and methods

DOEpatents

Semrau, Jeremy D; Gallagher, Warren; Yoon, Sukhwan; Im, Jeongdae; DiSpririto, Alan A; Lee, Sung-Woo; Hartsel, Scott; McEllistrem, Marcus T

2014-01-14

The present disclosures provides isolated or purified compounds, each of which bind to a metal atom. Generally, the compounds are small in size (e.g., molecular weight of less than about 1 kDa) and peptidic in nature, inasmuch as the compounds comprise amino acids. In some embodiments, the compound comprises a structure of Formula I; M.sub.1-P.sub.1-M.sub.2-P.sub.2 wherein each of P.sub.1 and P.sub.2 is a peptide comprising at least two amino acids, M.sub.1 is a first metal binding moiety comprising a substituted imidazolone ring, M.sub.2 is a second metal binding moiety comprising a substituted oxazolone ring, and wherein M.sub.1 and M.sub.2 bind to a single metal atom. Also provided are related complexes, conjugates, cells which synthesize the compounds of the present disclosures, substantially homogenous cultures thereof, kits and compositions, and methods of making or using the materials of the present disclosures.

A Rare Case of an Adult with Untreated Bladder Exstrophy Presenting with Signet-Ring Cell Adenocarcinoma of Urinary Bladder.

PubMed

Savalia, Abhishek J; Kumar, Vikash; Kasat, Gaurav; Sawant, Ajit

2016-11-01

Untreated bladder exstrophy in an adult is rare, as the defect is obvious and primary reconstruction is usually done in infancy. There are less than 90 reported cases of primary adenocarcinoma in an untreated bladder exstrophy in literature and only two such case reports from India. Of these, only one case was of signet-ring cell type of mucinous adenocarcinoma. Here we report the second case of signet-ring cell adenocarcinoma in a 63 year old male with untreated bladder exstrophy (oldest patient in literature), to highlight the extreme rarity, yet distinct possibility and challenges faced in surgical management of such cases.

Spontaneous actin dynamics in contractile rings

NASA Astrophysics Data System (ADS)

Kruse, Karsten; Wollrab, Viktoria; Thiagarajan, Raghavan; Wald, Anne; Riveline, Daniel

Networks of polymerizing actin filaments are known to be capable to self-organize into a variety of structures. For example, spontaneous actin polymerization waves have been observed in living cells in a number of circumstances, notably, in crawling neutrophils and slime molds. During later stages of cell division, they can also spontaneously form a contractile ring that will eventually cleave the cell into two daughter cells. We present a framework for describing networks of polymerizing actin filaments, where assembly is regulated by various proteins. It can also include the effects of molecular motors. We show that the molecular processes driven by these proteins can generate various structures that have been observed in contractile rings of fission yeast and mammalian cells. We discuss a possible functional role of each of these patterns. The work was supported by Agence Nationale de la Recherche, France, (ANR-10-LABX-0030-INRT) and by Deutsche Forschungsgemeinschaft through SFB1027.

Cytotoxic 2',5'-dihydroxychalcones with unexpected antiangiogenic activity.

PubMed

Nam, Nguyen-Hai; Kim, Yong; You, Young-Jae; Hong, Dong-Ho; Kim, Hwan-Mook; Ahn, Byung-Zun

2003-02-01

A series of 2',5'-dihydroxychalcones were synthesized and evaluated for cytotoxicity against tumor cell lines and human umbilical venous endothelial cells (HUVEC). It was found that chalcones with electron-withdrawing substituents on the B ring exhibited potent cytotoxicity against a variety of tumor cell lines while compounds with electron-releasing groups were less potent in general. Those compounds with B ring replaced by extended or heteroaromatic rings exhibited significant bioactivity. Several compounds were shown to have marked cytotoxic selectivity towards HUVECs. Especially, among the synthesized compounds, 2-chloro-2',5'-dihydroxychalcone (2-3) showed the highest selectivity index up to 66 in comparison to HCT116 cells. This compound also exhibited strong inhibitory effects on the HUVEC tube formation in an in vitro model. When administered into BDF1 mice bearing Lewis lung carcinoma cells at 50 mg kg(-1) day(-1), 2-3 was found to inhibit the growth of tumor mass by 60.5%.

Dynamics of Clumps in Saturn's F Ring

NASA Astrophysics Data System (ADS)

Showalter, M. R.

1997-07-01

An exhaustive analysis of the Voyager image data sets reveals the F Ring to be the most dynamic ring in the solar system. Principal properties are as follows. (1) At any given time, the ring holds 2--3 extremely bright clumps (each several times brighter than the local average for the ring) and perhaps 20--40 identifiable smaller clumps. In practice, the closer one looks at the rings, the finer detail one finds. (2) No major clumps persist for the nine months between the Voyager encounters, but most survive for the ~ 6 weeks they can be detected during a single encounter. (3) A few major clumps are seen to appear or disappear very quickly, on time scales as brief as days. One clump appears to spread longitudinally after it first appears, but other clumps stay roughly fixed in longitudinal extend. The processes behind clump formation and destruction are unknown. (4) Clumps propagate at different mean motions; there is no evidence for a discrete set of rates that might correspond to the individual ``strands'' described in some models. Motions range from 581.81(deg) /day to 582.41(deg) /day, implying that the F Ring's clumps span a semimajor axis range of ~ 80 km. (5) Some sections of the ring show a distinct 3.2(deg) periodicity in clump spacing, as expected from the gravitational perturbations by Prometheus. Others do not. (6) In the Voyager 2 images, a single prominent clump seems to eject smaller clumps behind it on time scales of ~ 2 weeks. However, nothing analogous is observed in Voyager 1 data.

Excitonic energy transfer in light-harvesting complexes in purple bacteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye Jun; Sun Kewei; Zhao Yang

Two distinct approaches, the Frenkel-Dirac time-dependent variation and the Haken-Strobl model, are adopted to study energy transfer dynamics in single-ring and double-ring light-harvesting (LH) systems in purple bacteria. It is found that the inclusion of long-range dipolar interactions in the two methods results in significant increase in intra- or inter-ring exciton transfer efficiency. The dependence of exciton transfer efficiency on trapping positions on single rings of LH2 (B850) and LH1 is similar to that in toy models with nearest-neighbor coupling only. However, owing to the symmetry breaking caused by the dimerization of BChls and dipolar couplings, such dependence has beenmore » largely suppressed. In the studies of coupled-ring systems, both methods reveal an interesting role of dipolar interactions in increasing energy transfer efficiency by introducing multiple intra/inter-ring transfer paths. Importantly, the time scale (4 ps) of inter-ring exciton transfer obtained from polaron dynamics is in good agreement with previous studies. In a double-ring LH2 system, non-nearest neighbor interactions can induce symmetry breaking, which leads to global and local minima of the average trapping time in the presence of a non-zero dephasing rate, suggesting that environment dephasing helps preserve quantum coherent energy transfer when the perfect circular symmetry in the hypothetic system is broken. This study reveals that dipolar coupling between chromophores may play an important role in the high energy transfer efficiency in the LH systems of purple bacteria and many other natural photosynthetic systems.« less

Comparison of accelerator physics issues for symmetric and asymmetric B-factory rings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tigner, M.

1990-10-10

A systematic comparison of accelerator physics issues from the beam-beam interaction to single particle stability including ring and IR layout, synchrotron radiation and lost particle backgrounds, and single and multi-bunch instabilities is given. While some practical handicap probably accrues to the asymmetric design because of its extra constraints, the differences in the two approaches tend to be obscured by larger issues such as how to achieve the enormous increases in luminosity demanded of a b-factory.

Cooperation between Paxillin-like Protein Pxl1 and Glucan Synthase Bgs1 Is Essential for Actomyosin Ring Stability and Septum Formation in Fission Yeast

PubMed Central

G. Cortés, Juan C.; Pujol, Nuria; Sato, Mamiko; Pinar, Mario; Ramos, Mariona; Moreno, Belén; Osumi, Masako; Ribas, Juan Carlos; Pérez, Pilar

2015-01-01

In fungal cells cytokinesis requires coordinated closure of a contractile actomyosin ring (CAR) and synthesis of a special cell wall structure known as the division septum. Many CAR proteins have been identified and characterized, but how these molecules interact with the septum synthesis enzymes to form the septum remains unclear. Our genetic study using fission yeast shows that cooperation between the paxillin homolog Pxl1, required for ring integrity, and Bgs1, the enzyme responsible for linear β(1,3)glucan synthesis and primary septum formation, is required for stable anchorage of the CAR to the plasma membrane before septation onset, and for cleavage furrow formation. Thus, lack of Pxl1 in combination with Bgs1 depletion, causes failure of ring contraction and lateral cell wall overgrowth towards the cell lumen without septum formation. We also describe here that Pxl1 concentration at the CAR increases during cytokinesis and that this increase depends on the SH3 domain of the F-BAR protein Cdc15. In consequence, Bgs1 depletion in cells carrying a cdc15ΔSH3 allele causes ring disassembly and septation blockage, as it does in cells lacking Pxl1. On the other hand, the absence of Pxl1 is lethal when Cdc15 function is affected, generating a large sliding of the CAR with deposition of septum wall material along the cell cortex, and suggesting additional functions for both Pxl1 and Cdc15 proteins. In conclusion, our findings indicate that CAR anchorage to the plasma membrane through Cdc15 and Pxl1, and concomitant Bgs1 activity, are necessary for CAR maintenance and septum formation in fission yeast. PMID:26132084

Cooperation between Paxillin-like Protein Pxl1 and Glucan Synthase Bgs1 Is Essential for Actomyosin Ring Stability and Septum Formation in Fission Yeast.

PubMed

Cortés, Juan C G; Pujol, Nuria; Sato, Mamiko; Pinar, Mario; Ramos, Mariona; Moreno, Belén; Osumi, Masako; Ribas, Juan Carlos; Pérez, Pilar

2015-07-01

In fungal cells cytokinesis requires coordinated closure of a contractile actomyosin ring (CAR) and synthesis of a special cell wall structure known as the division septum. Many CAR proteins have been identified and characterized, but how these molecules interact with the septum synthesis enzymes to form the septum remains unclear. Our genetic study using fission yeast shows that cooperation between the paxillin homolog Pxl1, required for ring integrity, and Bgs1, the enzyme responsible for linear β(1,3)glucan synthesis and primary septum formation, is required for stable anchorage of the CAR to the plasma membrane before septation onset, and for cleavage furrow formation. Thus, lack of Pxl1 in combination with Bgs1 depletion, causes failure of ring contraction and lateral cell wall overgrowth towards the cell lumen without septum formation. We also describe here that Pxl1 concentration at the CAR increases during cytokinesis and that this increase depends on the SH3 domain of the F-BAR protein Cdc15. In consequence, Bgs1 depletion in cells carrying a cdc15ΔSH3 allele causes ring disassembly and septation blockage, as it does in cells lacking Pxl1. On the other hand, the absence of Pxl1 is lethal when Cdc15 function is affected, generating a large sliding of the CAR with deposition of septum wall material along the cell cortex, and suggesting additional functions for both Pxl1 and Cdc15 proteins. In conclusion, our findings indicate that CAR anchorage to the plasma membrane through Cdc15 and Pxl1, and concomitant Bgs1 activity, are necessary for CAR maintenance and septum formation in fission yeast.

Vascular response of ruthenium tetraamines in aortic ring from normotensive rats.

PubMed

Conceição-Vertamatti, Ana Gabriela; Ramos, Luiz Alberto Ferreira; Calandreli, Ivy; Chiba, Aline Nunes; Franco, Douglas Wagner; Tfouni, Elia; Grassi-Kassisse, Dora Maria

2015-03-01

Ruthenium (Ru) tetraamines are being increasingly used as nitric oxide (NO) carriers. In this context, pharmacological studies have become highly relevant to better understand the mechanism of action involved. To evaluate the vascular response of the tetraamines trans-[Ru(II)(NH3)4(Py)(NO)](3+), trans-[Ru(II)(Cl)(NO) (cyclan)](PF6)2, and trans-[Ru(II)(NH3)4(4-acPy)(NO)](3+). Aortic rings were contracted with noradrenaline (10(-6) M). After voltage stabilization, a single concentration (10(-6) M) of the compounds was added to the assay medium. The responses were recorded during 120 min. Vascular integrity was assessed functionally using acetylcholine at 10(-6) M and sodium nitroprusside at 10(-6) M as well as by histological examination. Histological analysis confirmed the presence or absence of endothelial cells in those tissues. All tetraamine complexes altered the contractile response induced by norepinephrine, resulting in increased tone followed by relaxation. In rings with endothelium, the inhibition of endothelial NO caused a reduction of the contractile effect caused by pyridine NO. No significant responses were observed in rings with endothelium after treatment with cyclan NO. In contrast, in rings without endothelium, the inhibition of guanylate cyclase significantly reduced the contractile response caused by the pyridine NO and cyclan NO complexes, and both complexes caused a relaxing effect. The results indicate that the vascular effect of the evaluated complexes involved a decrease in the vascular tone induced by norepinephrine (10(-6) M) at the end of the incubation period in aortic rings with and without endothelium, indicating the slow release of NO from these complexes and suggesting that the ligands promoted chemical stability to the molecule. Moreover, we demonstrated that the association of Ru with NO is more stable when the ligands pyridine and cyclan are used in the formulation of the compound.

The Putative Exchange Factor Gef3p Interacts with Rho3p GTPase and the Septin Ring during Cytokinesis in Fission Yeast*

PubMed Central

Muñoz, Sofía; Manjón, Elvira; Sánchez, Yolanda

2014-01-01

The small GTP-binding proteins of the Rho family and its regulatory proteins play a central role in cytokinetic actomyosin ring assembly and cytokinesis. Here we show that the fission yeast guanine nucleotide exchange factor Gef3p interacts with Rho3p at the division site. Gef3p contains a putative DH homology domain and a BAR/IMD-like domain. The protein localized to the division site late in mitosis, where it formed a ring that did not constrict with actomyosin ring (cytokinetic actomyosin ring) invagination; instead, it split into a double ring that resembled the septin ring. Gef3p co-localized with septins and Mid2p and required septins and Mid2p for its localization. Gef3p interacts physically with the GTP-bound form of Rho3p. Although Gef3p is not essential for cell separation, the simultaneous disruption of gef3+ and Rho3p-interacting proteins, such as Sec8p, an exocyst component, Apm1p, a subunit of the clathrin adaptor complex or For3p, an actin-polymerizing protein, yielded cells with strong defects in septation and polarity respectively. Our results suggest that interactions between septins and Rho-GEFs provide a new targeting mechanism for GTPases in cytokinesis, in this case probably contributing to Rho3p function in vesicle tethering and vesicle trafficking in the later steps of cell separation. PMID:24947517

Lymphomas involving Waldeyer's ring: placement, paradigms, peculiarities, pitfalls, patterns and postulates.

PubMed

Tan, L H

2004-07-01

This review revisits Waldeyer's ring lymphomas as classified by the World Health Organisation. Sources of data include international studies on Waldeyer's ring lymphomas as well as from personal observations gleaned from lymphoma statistics of Singapore General Hospital, Changi General Hospital, Tan Tock Seng Hospital and National University Hospital within the last decade or so. Waldeyer's ring shares many of the histopathological trends of the rest of mucosa-associated lymphoid tissue (MALT), such as the high frequency of diffuse large B-cell lymphomas, and the relative rarity of follicular lymphomas in spite of its rich endowment with reactive lymphoid follicles. However, extranodal marginal zone lymphoma or "MALToma" may not be as frequently encountered as in other mucosal sites. Furthermore, the placement of Waldeyer's ring is unique in that stark comparisons with the lymphopathology of the immediately anterior oronasal cavities can be made, with intriguing peculiarities such as the abrupt reversal of the ratio of B-cell to T/NK-cell lymphoma frequency upon crossing the imaginary line that separates the 2 regions. The differential diagnosis with regionally common lymphoma mimics, in particular reactive parafollicular hyperplasia and nasopharyngeal undifferentiated (lymphoepithelial) carcinoma of Schmincke pattern, both often aetiologically related to Epstein-Barr viral infection, is also discussed. Recognition of the peculiarities and patterns of Waldeyer's ring lymphomas is important for accurate pathologic assessment. Postulates that attempt to account for the patterns and peculiarities of Waldeyer's ring lymphopathology can be used to direct further research.

Nitrile O-ring Cracking: A Case of Vacuum Flange O-ring Failures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dees, Craig

2016-07-01

A review of recent nitrile O-ring failures in ISO-KF vacuum flange connections in glovebox applications is presented. An investigation of a single “isolated” o-ring failure leads to the discovery of cracked nitrile o-rings in a glovebox atmospheric control unit. The initial cause of the o-ring failure is attributed to ozone degradation. However, additional investigation reveals nitrile o-ring cracking on multiple gloveboxes and general purpose piping, roughly 85% of the nitrile o-rings removed for inspection show evidence of visible cracking after being in service for 18 months or less. The results of material testing and ambient air testing is presented, elevatedmore » ozone levels are not found. The contributing factors of o-ring failure, including nitrile air sensitivity, inadequate storage practices, and poor installation techniques, are discussed. A discussion of nitrile o-ring material properties, the benefits and limitations, and alternate materials are discussed. Considerations for o-ring material selection, purchasing, storage, and installation are presented in the context of lessons learned from the nitrile o-ring cracking investigation. This paper can be presented in 20 minutes and does not require special accommodations or special audio visual devices.« less

The effect of packing hydrophilization on bacterial attachment and the relationship with the performance of biotrickling filters.

PubMed

Prado, Oscar J; Popat, Sudeep C; Chen, Gexin; Walker, Sharon L; Lafuente, Javier; Gabriel, David; Deshusses, Marc A

2009-08-15

Many bioprocesses depend on the effective formation of a biofilm on a solid support. In the present study, three different surface treatments (sandblasting, pure-O(2) plasma, and He-O(2) plasma treatments) were conducted on polypropylene (PP) Pall rings used as a support in biotrickling filters for air pollution control. The intent was to modify the ring surface and/or electrochemical properties in order to possibly improve cell adhesion, wetting properties, and possibly reduce the start-up time and increase the performance of the biotrickling filters. The surface treatments were found to generally increase the hydrophilicity and the zeta potential of the surfaces. However, the startup and performance of lab-scale biotrickling filters packed with treated Pall rings were not significantly different than the control with untreated rings. Cell and colloid deposition experiments conducted in flow cells showed that the treated surfaces and the hydrodynamic conditions were not favorable for cell deposition indicating that there could be significant opportunities for improving packings used in environmental bioprocess applications. Copyright 2009 Wiley Periodicals, Inc.

Breast metastasis of gastric signet-ring cell carcinoma: a case report and literature review.

PubMed

He, Chun-Lan; Chen, Ping; Xia, Bing-Lan; Xiao, Qin; Cai, Feng-Lin

2015-03-26

Cases of primary gastric adenocarcinoma with metastasis to the breast are extremely rare. Till now, only 38 cases have been reported in PubMed since 1908. We herein reported a race case of gastric adenocarcinoma with metastasis to the right breast. Breast biopsy showed invasive signet-ring cell breast carcinoma in the right breast. She was given a TEC regimen (docetaxel 75 mg/m(2), epirubicin 75 mg/m(2), and cyclophosphamide 600 mg/m(2) every 3 weeks) for one cycle but showed no objective response. Upper gastrointestinal endoscopy demonstrated an ulcerative mass in the gastric body. Biopsy demonstrated low-grade gastric adenocarcinoma with signet-ring features. In immunohistochemistry, mammary malignant cells were positive for cytokeratin 7, cytokeratin 20, villin, and ErbB2/HER2, but negative for gross cystic disease fluid protein-15, estrogen receptor, and progesterone receptor. The diagnosis of metastatic poorly differentiated signet-ring cell adenocarcinoma of the right breast identical to gastric primary was confirmed finally. Gastric cancer with metastasis to the breast can be diagnosed by clinical history, histological findings, and immunohistochemical markers.

Signet-ring cell carcinoma of the breast with uterine metastasis treated with extensive cytoreductive surgery: a case report and brief review of the literature.

PubMed

Ertas, Ibrahim Egemen; Sayhan, Sevil; Karagoz, Gurhan; Yildirim, Yusuf

2012-06-01

Primary signet-ring cell carcinoma (SRCC) of the breast is an uncommon variant, accounting for 2-4.5% of all primary breast cancers. Secondary SRCC of the endometrium is very rare and usually originates from the breast or gastrointestinal tract. A 54-year-old, postmenopausal woman with a past history of breast cancer four years previously was admitted with abnormal uterine bleeding. An endometrial biopsy revealed undifferentiated adenocarcinoma with signet-ring cells. The patient underwent laparotomy and cytoreductive surgery was performed. Pathological analysis and immunohistochemical tests demonstrated a uterine (endomyometrial) metastasis of breast SRCC. Omentum, peritoneal surfaces and retroperitoneal lymph nodes also included tumoral tissue with signet-ring cell morphology. The patient received adjuvant systemic chemotherapy with adriamycin, cyclophosphamide and paclitaxel. This case report discusses the patient's clinical characteristics and the role of cytoreductive surgery on patient survival in SRCC of the breast metastasizing to the uterus. © 2012 The Authors. Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology.

Theoretical design of twelve-band infrared metamaterial perfect absorber by combining the dipole, quadrupole, and octopole plasmon resonance modes of four different ring-strip resonators.

PubMed

Zhao, Lei; Liu, Han; He, Zhihong; Dong, Shikui

2018-05-14

Multiband metamaterial perfect absorbers (MPAs) have promising applications in many fields like microbolometers, infrared detection, biosensing, and thermal emitters. In general, the single resonator can only excite a fundamental mode and achieve single absorption band. The multiband MPA can be achieved by combining several different sized resonators together. However, it's still challenging to design the MPA with absorption bands of more than four and average absorptivity of more than 90% due to the interaction between differently sized resonators. In this paper, three absorption bands are successfully achieved with average absorptivity up to 98.5% only utilizing single one our designed ring-strip resonator, which can simultaneously excite a fundamental electric dipole mode, a higher-order electric quadrupole mode, and a higher-order electric octopole mode. As the biosensor, the sensing performance of the higher-order modes is higher than the fundamental modes. Then we try to increase the absorption bands by combining different sized ring-strip resonators together and make the average absorptivity above 90% by optimizing the geometry parameters. A six-band MPA is achieved by combining two different sized ring-strip resonators with average absorptivity up to 98.8%, which can excite two dipole modes, two quadrupole modes, and two octopole modes. A twelve-band MPA is achieved by combining four different sized ring-strip resonators with average absorptivity up to 93.7%, which can excite four dipole modes, four quadrupole modes, and four octopole modes.

Variable focal length deformable mirror

DOEpatents

Headley, Daniel [Albuquerque, NM; Ramsey, Marc [Albuquerque, NM; Schwarz, Jens [Albuquerque, NM

2007-06-12

A variable focal length deformable mirror has an inner ring and an outer ring that simply support and push axially on opposite sides of a mirror plate. The resulting variable clamping force deforms the mirror plate to provide a parabolic mirror shape. The rings are parallel planar sections of a single paraboloid and can provide an on-axis focus, if the rings are circular, or an off-axis focus, if the rings are elliptical. The focal length of the deformable mirror can be varied by changing the variable clamping force. The deformable mirror can generally be used in any application requiring the focusing or defocusing of light, including with both coherent and incoherent light sources.

Article mounting and position adjustment stage

DOEpatents

Cutburth, R.W.; Silva, L.L.

1988-05-10

An improved adjustment and mounting stage of the type used for the detection of laser beams is disclosed. A ring sensor holder has locating pins on a first side thereof which are positioned within a linear keyway in a surrounding housing for permitting reciprocal movement of the ring along the keyway. A rotatable ring gear is positioned within the housing on the other side of the ring from the linear keyway and includes an oval keyway which drives the ring along the linear keyway upon rotation of the gear. Motor-driven single-stage and dual (x, y) stage adjustment systems are disclosed which are of compact construction and include a large laser transmission hole. 6 figs.

Article mounting and position adjustment stage

DOEpatents

Cutburth, Ronald W.; Silva, Leonard L.

1988-01-01

An improved adjustment and mounting stage of the type used for the detection of laser beams is disclosed. A ring sensor holder has locating pins on a first side thereof which are positioned within a linear keyway in a surrounding housing for permitting reciprocal movement of the ring along the keyway. A rotatable ring gear is positioned within the housing on the other side of the ring from the linear keyway and includes an oval keyway which drives the ring along the linear keyway upon rotation of the gear. Motor-driven single-stage and dual (x, y) stage adjustment systems are disclosed which are of compact construction and include a large laser transmission hole.

Nitrited-Steel Piston Rings for Engines of High Specific Power

NASA Technical Reports Server (NTRS)

Collins, John H; Bisson, Edmond E; Schmiedlin, Ralph F

1945-01-01

Stability and control characteristics determined from tests in the Langley 19-foot pressure tunnel of a 0.2375-scale model of the Douglas XA-26 airplane are compared with those measured in flight tests of a Douglas A-26b airplane. Several designs of nitrided-steel piston rings were performance-tested under variable conditions of output. The necessity of good surface finish and conformity of the ring to the bore was indicated in the preliminary tests. Nitrided-steel rings of the same dimensions as cast-iron rings operating on the original piston were unsatisfactory, and the final design was a lighter, rectangular, thin-face-width ring used on a piston having a maximum cross-head area and a revised skirt shape. Results were obtained from single-cylinder and multicylinder engine runs.

Primary mucinous carcinoma of thyroid gland with prominent signet-ring-cell differentiation: a case report and review of the literature.

PubMed

Wang, Jian; Guli, Qie-Re; Ming, Xiao-Cui; Zhou, Hai-Tao; Cui, Yong-Jie; Jiang, Yue-Feng; Zhang, Di; Liu, Yang

2018-01-01

This study reports a case of primary mucinous carcinoma of the thyroid gland with signet-ring-cell differentiation, and reviews the literature to evaluate its real incidence and the prognosis of these patients. A 74-year-old Chinese woman, presenting with a mass in the right lobe of thyroid gland, came to the hospital. Computed tomography revealed a mass in the right lobe of the thyroid gland, accompanied with right neck lymphadenectasis and airway deviation caused by tumor compression. Thyroid imaging suggested a thyroid malignant tumor and suspicious lymph node metastasis. Histologically, the tumor was characterized by the tumor cells arranged in small nests or trabeculae with an abundant extracellular mucoid matrix. The tumor cells formed diffuse invasion among thyroid follicles. In the peripheral regions, prominent signet-ring-cells formed a sheet-like structure and extended into the extrathyroidal fat tissue. The tumor cells were diffusely positive for thyroid transcription factor-1 (TTF-1) and PAX8, while they were focally positive for pan-cytokeratin (AE1/AE3) and weakly expressed thyroglobulin. Based on the histological features and immunohistochemical profile, a diagnosis of primary mucinous carcinoma of the thyroid gland with signet-ring-cell differentiation was rendered. Using a panel of immunohistochemical markers may be helpful for differential diagnosis and for determining whether the tumor is primary or not.

Optical Add-Drop Filters Based on Photonic Crystal Ring Resonators

DTIC Science & Technology

2007-02-19

34 Appl. Phys. Lett. 81,2499-2501 (2002). 17. V. Dinesh Kumar , T. Srinivas, A. Selvarajan, "Investigation of ring resonators in photonic crystal...No.4 / opncs EXPRESS 1824 Kumar et al. [17], where a large single quasi-rectangular ring was introduced as the frequency selective dropping elements...were introduced by Kumar et al. as well, in order to suppress the counter propagating modes which can cause spurious dips in the transmission spectrum

FIBER OPTICS: Polarization phase nonreciprocity in all-fiber ring interferometers

NASA Astrophysics Data System (ADS)

Andreev, A. Ts; Vasilev, V. D.; Kozlov, V. A.; Kuznetsov, A. V.; Senatorov, A. A.; Shubochkin, R. L.

1993-08-01

The polarization phase nonreciprocity in all-fiber ring interferometers based on single-mode optical fibers was studied experimentally. The results confirm existing theoretical models. Experimentally, it was possible to use fiber ring interferometers to measure the extinction coefficients of optical fiber polarizers. The largest extinction coefficients found for optical-fiber polarizers were 84 dB (for the wavelength 0.82 μm) and 86 dB (1.3 μm).

A multiple-orbit time-of-flight mass spectrometer based on a low energy electrostatic storage ring

NASA Astrophysics Data System (ADS)

Sullivan, M. R.; Spanjers, T. L.; Thorn, P. A.; Reddish, T. J.; Hammond, P.

2012-11-01

The results are presented for an electrostatic storage ring, consisting of two hemispherical deflector analyzers (HDA) connected by two separate sets of cylindrical lenses, used as a time-of-flight mass spectrometer. Based on the results of charged particle simulations and formal matrix model, the Ion Storage Ring is capable of operating with multiple stable orbits, for both single and multiply charged ions simultaneously.

Interaction of a vortex ring and a bubble

NASA Astrophysics Data System (ADS)

Jha, Narsing K.; Govardhan, Raghuraman N.

2014-11-01

Micro-bubble injection in to boundary layers is one possible method for reducing frictional drag of ships. Although this has been studied for some time, the physical mechanisms responsible for drag reduction using microbubbles in turbulent boundary layers is not yet fully understood. Previous studies suggest that bubble-vortical structure interaction seems to be one of the important physical mechanisms for frictional drag reduction using microbubbles. In the present work, we study a simplification of this problem, namely, the interaction of a single vortical structure, in particular a vortex ring, with a single bubble for better understanding of the physics. The vortex ring is generated using a piston-cylinder arrangement and the bubble is generated by connecting a capillary to an air pump. The bubble dynamics is directly visualized using a high speed camera, while the vorticity modification is measured using time resolved PIV. The results show that significant deformations can occur of both the bubble and the vortex ring. Effect of different non-dimensional parameters on the interaction will be presented in the meeting.

Design of 8-ft-Diameter Barrel Test Article Attachment Rings for Shell Buckling Knockdown Factor Project

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Hilburger, Mark W.

2010-01-01

The Shell Buckling Knockdown Factor (SBKF) project includes the testing of sub-scale cylinders to validate new shell buckling knockdown factors for use in the design of the Ares-I and Ares-V launch vehicles. Test article cylinders represent various barrel segments of the Ares-I and Ares-V vehicles, and also include checkout test articles. Testing will be conducted at Marshall Space Flight Center (MSFC) for test articles having an eight-foot diameter outer mold line (OML) and having lengths that range from three to ten feet long. Both ends of the test articles will be connected to the test apparatus using attachment rings. Three multiple-piece and one single-piece design for the attachment rings were developed and analyzed. The single-piece design was chosen and will be fabricated from either steel or aluminum (Al) depending on the required safety factors (SF) for test hardware. This report summarizes the design and analysis of these attachment ring concepts.

Aquaporin 0 plays a pivotal role in refractive index gradient development in mammalian eye lens to prevent spherical aberration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumari, S. Sindhu; Varadaraj, Kulandaiappan, E-mail: kulandaiappan.varadaraj@stonybrook.edu; SUNY Eye Institute, New York, NY

Highlights: • Intact AQP0 functions as fiber cell-to-fiber cell adhesion protein. • AQP0 facilitates reduction in extracellular space and lens water content. • AQP0 adhesion function aids in lens refractive index gradient (RING) formation. • AQP0 prevents lens spherical aberration by establishing RING. • AQP0 is critical for lens transparency and homeostasis. - Abstract: Aquaporin 0 (AQP0) is a transmembrane channel that constitutes ∼45% of the total membrane protein of the fiber cells in mammalian lens. It is critical for lens transparency and homeostasis as mutations and knockout cause autosomal dominant lens cataract. AQP0 functions as a water channel andmore » as a cell-to-cell adhesion (CTCA) molecule in the lens. Our recent in vitro studies showed that the CTCA function of AQP0 could be crucial to establish lens refractive index gradient (RING). However, there is a lack of in vivo data to corroborate the role of AQP0 as a fiber CTCA molecule which is critical for creating lens RING. The present investigation is undertaken to gather in vivo evidence for the involvement of AQP0 in developing lens RING. Lenses of wild type (WT) mouse, AQP0 knockout (heterozygous, AQP0{sup +/−}) and AQP0 knockout lens transgenically expressing AQP1 (heterozygous AQP0{sup +/−}/AQP1{sup +/−}) mouse models were used for the study. Data on AQP0 protein profile of intact and N- and/or C-terminal cleaved AQP0 in the lens by MALDI-TOF mass spectrometry and SDS–PAGE revealed that outer cortex fiber cells have only intact AQP0 of ∼28 kDa, inner cortical and outer nuclear fiber cells have both intact and cleaved forms, and inner nuclear fiber cells have only cleaved forms (∼26–24 kDa). Knocking out of 50% of AQP0 protein caused light scattering, spherical aberration (SA) and cataract. Restoring the lost fiber cell membrane water permeability (P{sub f}) by transgene AQP1 did not reinstate complete lens transparency and the mouse lenses showed light scattering and SA. Transmission and scanning electron micrographs of lenses of both mouse models showed increased extracellular space between fiber cells. Water content determination study showed increase in water in the lenses of these mouse models. In summary, lens transparency, CTCA and compact packing of fiber cells were affected due to the loss of 50% AQP0 leading to larger extracellular space, more water content and SA, possibly due to alteration in RING. To our knowledge, this is the first report identifying the role of AQP0 in RING development to ward off lens SA during focusing.« less

Assembly of tissue engineered blood vessels with spatially-controlled heterogeneities.

PubMed

Strobel, Hannah A; Hookway, Tracy; Piola, Marco; Fiore, Gianfranco Beniamino; Soncini, Monica; Alsberg, Eben; Rolle, Marsha

2018-05-04

Tissue-engineered human blood vessels may enable in vitro disease modeling and drug screening to accelerate advances in vascular medicine. Existing methods for tissue engineered blood vessel (TEBV) fabrication create homogenous tubes not conducive to modeling the focal pathologies characteristic of vascular disease. We developed a system for generating self-assembled human smooth muscle cell ring-units, which were fused together into TEBVs. The goal of this study was to assess the feasibility of modular assembly and fusion of ring building units to fabricate spatially-controlled, heterogeneous tissue tubes. We first aimed to enhance fusion and reduce total culture time, and determined that reducing ring pre-culture duration improved tube fusion. Next, we incorporated electrospun polymer ring units onto tube ends as reinforced extensions, which allowed us to cannulate tubes after only 7 days of fusion, and culture tubes with luminal flow in a custom bioreactor. To create focal heterogeneities, we incorporated gelatin microspheres into select ring units during self-assembly, and fused these rings between ring units without microspheres. Cells within rings maintained their spatial position within tissue tubes after fusion. This work describes a platform approach for creating modular TEBVs with spatially-defined structural heterogeneities, which may ultimately be applied to mimic focal diseases such as intimal hyperplasia or aneurysm.

Cryo-EM of the pathogenic VCP variant R155P reveals long-range conformational changes in the D2 ATPase ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mountassif, Driss; Fabre, Lucien; Zaid, Younes

Single amino acid mutations in valosin containing protein (VCP/p97), a highly conserved member of the ATPases associated with diverse cellular activities (AAA) family of ATPases has been linked to a severe degenerative disease affecting brain, muscle and bone tissue. Previous studies have demonstrated the role of VCP mutations in altering the ATPase activity of the D2 ring; however the structural consequences of these mutations remain unclear. In this study, we report the three-dimensional (3D) map of the pathogenic VCP variant, R155P, as revealed by single-particle Cryo-Electron Microscopy (EM) analysis at 14 Å resolution. We show that the N-terminal R155P mutation inducesmore » a large structural reorganisation of the D2 ATPase ring. Results from docking studies using crystal structure data of available wild-type VCP in the EM density maps indicate that the major difference is localized at the interface between two protomers within the D2 ring. Consistent with a conformational change, the VCP R155P variant shifted the isoelectric point of the protein and reduced its interaction with its well-characterized cofactor, nuclear protein localization-4 (Npl4). Together, our results demonstrate that a single amino acid substitution in the N-terminal domain can relay long-range conformational changes to the distal D2 ATPase ring. Our results provide the first structural clues of how VCP mutations may influence the activity and function of the D2 ATPase ring. - Highlights: • p97{sub R155P} and p97{sub A232E} decrease the ability of p97 to bind to its co-factor Npl4. • p97{sub R155P} has a different isoelectric point than that of p97{sub R95G}, p97{sub A232E} and p97{sub WT}. • Mutation R155P changes principally the conformation of the D2 ring. • Mutation R155P modifies the interface between two protomers within the D2 ring.« less

Small slot waveguide rings for on-chip quantum optical circuits.

PubMed

Rotenberg, Nir; Türschmann, Pierre; Haakh, Harald R; Martin-Cano, Diego; Götzinger, Stephan; Sandoghdar, Vahid

2017-03-06

Nanophotonic interfaces between single emitters and light promise to enable new quantum optical technologies. Here, we use a combination of finite element simulations and analytic quantum theory to investigate the interaction of various quantum emitters with slot-waveguide rings. We predict that for rings with radii as small as 1.44 μm, with a Q-factor of 27,900, near-unity emitter-waveguide coupling efficiencies and emission enhancements on the order of 1300 can be achieved. By tuning the ring geometry or introducing losses, we show that realistic emitter-ring systems can be made to be either weakly or strongly coupled, so that we can observe Rabi oscillations in the decay dynamics even for micron-sized rings. Moreover, we demonstrate that slot waveguide rings can be used to directionally couple emission, again with near-unity efficiency. Our results pave the way for integrated solid-state quantum circuits involving various emitters.

Incorporation of a two metre long PET scanner in STIR

NASA Astrophysics Data System (ADS)

Tsoumpas, C.; Brain, C.; Dyke, T.; Gold, D.

2015-09-01

The Explorer project aims to investigate the potential benefits of a total-body 2 metre long PET scanner. The following investigation incorporates this scanner in STIR library and demonstrates the capabilities and weaknesses of existing reconstruction (FBP and OSEM) and single scatter simulation algorithms. It was found that sensible images are reconstructed but at the expense of high memory and processing time demands. FBP requires 4 hours on a core; OSEM: 2 hours per iteration if ran in parallel on 15-cores of a high performance computer. The single scatter simulation algorithm shows that on a short scale, up to a fifth of the scanner length, the assumption that the scatter between direct rings is similar to the scatter between the oblique rings is approximately valid. However, for more extreme cases this assumption is not longer valid, which illustrates that consideration of the oblique rings within the single scatter simulation will be necessary, if this scatter correction is the method of choice.

Bayesian multiproxy temperature reconstruction with black spruce ring widths and stable isotopes from the northern Quebec taiga

NASA Astrophysics Data System (ADS)

Gennaretti, Fabio; Huard, David; Naulier, Maud; Savard, Martine; Bégin, Christian; Arseneault, Dominique; Guiot, Joel

2017-12-01

Northeastern North America has very few millennium-long, high-resolution climate proxy records. However, very recently, a new tree-ring dataset suitable for temperature reconstructions over the last millennium was developed in the northern Quebec taiga. This dataset is composed of one δ18O and six ring width chronologies. Until now, these chronologies have only been used in independent temperature reconstructions (from δ18O or ring width) showing some differences. Here, we added to the dataset a δ13C chronology and developed a significantly improved millennium-long multiproxy reconstruction (997-2006 CE) accounting for uncertainties with a Bayesian approach that evaluates the likelihood of each proxy model. We also undertook a methodological sensitivity analysis to assess the different responses of each proxy to abrupt forcings such as strong volcanic eruptions. Ring width showed a larger response to single eruptions and a larger cumulative impact of multiple eruptions during active volcanic periods, δ18O showed intermediate responses, and δ13C was mostly insensitive to volcanic eruptions. We conclude that all reconstructions based on a single proxy can be misleading because of the possible reduced or amplified responses to specific forcing agents.

Local spin density in the Cr 7Ni antiferromagnetic molecular ring and 53Cr-NMR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casadei, Cecilia M; Bordonali, L; Furukawa, Yuji

We present 53Cr-NMR spectra collected at low temperature in a single crystal of the heterometallic antiferromagnetic (AF) ring Cr 7Ni in the S = 1/2 ground state with the aim of establishing the distribution of the local electronic moment in the ring. Due to the poor S/N we observed only one signal which is ascribed to three almost equivalent 53Cr nuclei in the ring. The calculated spin density in Cr 7Ni in the ground state, with the applied magnetic field both parallel and perpendicular to the plane of the ring, turns out to be AF staggered with the greatest componentmore » of the local spin {s} for the Cr 3+ ions next to the Ni 2+ ion. The 53Cr-NMR frequency was found to be in good agreement with the local spin density calculated theoretically by assuming a core polarization field of H cp =₋ 11 T/μ B for both orientations, close to the value found previously in Cr 7Cd. Lastly, the observed orientation dependence of the local spin moments is well reproduced by the theoretical calculation and evidences the importance of single-ion and dipolar anisotropies.« less

Mobilization of Copper ions by Flavonoids in Human Peripheral Lymphocytes Leads to Oxidative DNA Breakage: A Structure Activity Study.

PubMed

Arif, Hussain; Rehmani, Nida; Farhan, Mohd; Ahmad, Aamir; Hadi, Sheikh Mumtaz

2015-11-09

Epidemiological studies have linked dietary consumption of plant polyphenols with lower incidence of various cancers. In particular, flavonoids (present in onion, tomato and other plant sources) induce apoptosis and cytotoxicity in cancer cells. These can therefore be used as lead compounds for the synthesis of novel anticancer drugs with greater bioavailability. In the present study, we examined the chemical basis of cytotoxicity of flavonoids by studying the structure-activity relationship of myricetin (MN), fisetin (FN), quercetin (QN), kaempferol (KL) and galangin (GN). Using single cell alkaline gel electrophoresis (comet assay), we established the relative efficiency of cellular DNA breakage as MN > FN > QN > KL > GN. Also, we determined that the cellular DNA breakage was the result of mobilization of chromatin-bound copper ions and the generation of reactive oxygen species. The relative DNA binding affinity order was further confirmed using molecular docking and thermodynamic studies through the interaction of flavonoids with calf thymus DNA. Our results suggest that novel anti-cancer molecules should have ortho-dihydroxy groups in B-ring and hydroxyl groups at positions 3 and 5 in the A-ring system. Additional hydroxyl groups at other positions further enhance the cellular cytotoxicity of the flavonoids.

Mobilization of Copper ions by Flavonoids in Human Peripheral Lymphocytes Leads to Oxidative DNA Breakage: A Structure Activity Study

PubMed Central

Arif, Hussain; Rehmani, Nida; Farhan, Mohd; Ahmad, Aamir; Hadi, Sheikh Mumtaz

2015-01-01

Epidemiological studies have linked dietary consumption of plant polyphenols with lower incidence of various cancers. In particular, flavonoids (present in onion, tomato and other plant sources) induce apoptosis and cytotoxicity in cancer cells. These can therefore be used as lead compounds for the synthesis of novel anticancer drugs with greater bioavailability. In the present study, we examined the chemical basis of cytotoxicity of flavonoids by studying the structure–activity relationship of myricetin (MN), fisetin (FN), quercetin (QN), kaempferol (KL) and galangin (GN). Using single cell alkaline gel electrophoresis (comet assay), we established the relative efficiency of cellular DNA breakage as MN > FN > QN > KL > GN. Also, we determined that the cellular DNA breakage was the result of mobilization of chromatin-bound copper ions and the generation of reactive oxygen species. The relative DNA binding affinity order was further confirmed using molecular docking and thermodynamic studies through the interaction of flavonoids with calf thymus DNA. Our results suggest that novel anti-cancer molecules should have ortho-dihydroxy groups in B-ring and hydroxyl groups at positions 3 and 5 in the A-ring system. Additional hydroxyl groups at other positions further enhance the cellular cytotoxicity of the flavonoids. PMID:26569217

Near Infrared Photometry of the Jovian Ring and Adrastea

NASA Astrophysics Data System (ADS)

Meier, Roland; Smith, Bradford A.; Owen, Tobias C.; Becklin, E. E.; Terrile, Richard J.

1999-10-01

The near IR spectral reflectance of the Jupiter dust ring is poorly known because of problems with scattered light from the planet. Here we report colors for the jovian ring and one of the two ring satellites, Adrastea, using observations from the near-IR camera NICMOS on the Hubble Space Telescope. Near the time when the Earth crossed the jovian ring plane in the fall of 1997, we recorded broad-band images at ˜1.1 (F110W), ˜1.6 (F160W), and ˜2.05 μm (F205W) and derived a single-pass, in radial direction measured ring brightness of 19.19±0.07, 18.76±0.06, and 18.49±0.04 mag linear arcsec -1, respectively. These single-pass radial ring brightnesses were derived from the observable part of the ring at a projected distance of >1.2 RJ using a model to remove projection effects. The corresponding apparent magnitudes for Adrastea are 18.30±0.10 (F110W), 17.73±0.09 (F160W), and 17.57±0.07 mag (F205W), obtained at a phase angle of φ=11.3°. The relative spectral reflectance of the ring and that of Adrastea turn out to be nearly identical, slightly reddish with a slope of about 15-20% between 1 and 2 μm. No evidence for transient ice crystals to be present in the main ring is seen. Our data are also in reasonable agreement with earlier ground-based measurements by Neugebauer et al. (1981), if we take their relatively large errors into account. The similarities of the colors of all inner satellites, including Io, are striking. The measured ring color provides evidence that the backscattered light from the ring is due to grains with mean particle sizes in excess of several micrometers. We were also able to infer a spatial particle distribution for the main ring. Its radial surface-density profile peaks sharply near the outer edge of the ring at the orbit of Adrastea, suggesting a strong dynamical relationship between the satellite and the ring particles. Our radial profile of the main ring is in excellent agreement with the results from Voyager images in backscattered light at visible wavelengths, except that we could not resolve any fine structures. The halo above and below the ring plane with a peak brightness near the inner edge of the ring appears to have a blue color compared to the main ring, but due to the low surface brightness of the halo the statistical significance of this color trend is only marginal. Such a color trend would be consistent with a dust population dominated by particles smaller than those in the main ring.

Improved power steering with double and triple ring waveguide systems: the impact of the operating frequency.

PubMed

Kok, H P; de Greef, M; Borsboom, P P; Bel, A; Crezee, J

2011-01-01

Regional hyperthermia systems with 3D power steering have been introduced to improve tumour temperatures. The 3D 70-MHz AMC-8 system has two rings of four waveguides. The aim of this study is to evaluate whether T(90) will improve by using a higher operating frequency and whether further improvement is possible by adding a third ring. Optimised specific absorption rate (SAR) distributions were evaluated for a centrally located target in tissue-equivalent phantoms, and temperature optimisation was performed for five cervical carcinoma patients with constraints to normal tissue temperatures. The resulting T(90) and the thermal iso-effect dose (i.e. the number of equivalent min at 43°C) were evaluated and compared to the 2D 70-MHz AMC-4 system with a single ring of four waveguides. FDTD simulations were performed at 2.5 × 2.5 × 5 mm(3) resolution. The applied frequencies were 70, 100, 120, 130, 140 and 150 MHz. Optimised SAR distributions in phantoms showed an optimal SAR distribution at 140 MHz. For the patient simulations, an optimal increase in T(90) was observed at 130 MHz. For a two-ring system at 70 MHz the gain in T(90) was about 0.5°C compared to the AMC-4 system, averaged over the five patients. At 130 MHz the average gain in T(90) was ~1.5°C and ~2°C for a two and three-ring system, respectively. This implies an improvement of the thermal iso-effect dose with a factor ~12 and ~30, respectively. Simulations showed that a 130-MHz two-ring waveguide system yields significantly higher tumour temperatures compared to 70-MHz single-ring and double-ring waveguide systems. Temperatures were further improved with a 130-MHz triple-ring system.

A numerical study of viscous vortex rings using a spectral method

NASA Technical Reports Server (NTRS)

Stanaway, S. K.; Cantwell, B. J.; Spalart, Philippe R.

1988-01-01

Viscous, axisymmetric vortex rings are investigated numerically by solving the incompressible Navier-Stokes equations using a spectral method designed for this type of flow. The results presented are axisymmetric, but the method is developed to be naturally extended to three dimensions. The spectral method relies on divergence-free basis functions. The basis functions are formed in spherical coordinates using Vector Spherical Harmonics in the angular directions, and Jacobi polynomials together with a mapping in the radial direction. Simulations are performed of a single ring over a wide range of Reynolds numbers (Re approximately equal gamma/nu), 0.001 less than or equal to 1000, and of two interacting rings. At large times, regardless of the early history of the vortex ring, it is observed that the flow approaches a Stokes solution that depends only on the total hydrodynamic impulse, which is conserved for all time. At small times, from an infinitely thin ring, the propagation speeds of vortex rings of varying Re are computed and comparisons are made with the asymptotic theory by Saffman. The results are in agreement with the theory; furthermore, the error is found to be smaller than Saffman's own estimate by a factor square root ((nu x t)/R squared) (at least for Re=0). The error also decreases with increasing Re at fixed core-to-ring radius ratio, and appears to be independent of Re as Re approaches infinity). Following a single ring, with Re=500, the vorticity contours indicate shedding of vorticity into the wake and a settling of an initially circular core to a more elliptical shape, similar to Norbury's steady inviscid vortices. Finally, we consider the case of leapfrogging vortex rings with Re=1000. The results show severe straining of the inner vortex core in the first pass and merging of the two cores during the second pass.

Physical and Thermal Comfort Properties of Viscose Fabrics made from Vortex and Ring Spun Yarns

NASA Astrophysics Data System (ADS)

Thilagavathi, G.; Muthukumar, N.; Kumar, V. Kiran; Sadasivam, Sanjay; Sidharth, P. Mithun; Nikhil Jain, G.

2017-06-01

Viscose fiber is frequently preferred for various types of inner and outer knitwear products for its comfort and visual characteristics. In this study, the physical and thermal comfort properties of viscose fabrics made from ring and vortex yarns have been studied to explore the impact of spinning process on fabric properties. 100% viscose fibers were spun into yarns by ring and vortex spinning and the developed yarns were converted to single jersey fabrics. The results indicated that fabrics made from vortex spun yarns had better pilling resistance over that of those from ring spun yarns. There was no significant difference between bursting strength values of vortex and ring spun yarn fabrics. Fabrics made from ring yarn had better dimensional stability compared to fabrics made from vortex yarn. The air permeability and water vapour permeability of vortex yarn fabrics were higher than ring spun yarn fabrics. The vortex yarn fabrics had better thermal comfort properties compared to ring yarn fabrics.

Electronic structures of GaAs/AlxGa1-xAs quantum double rings

PubMed Central

Xia, Jian-Bai

2006-01-01

In the framework of effective mass envelope function theory, the electronic structures of GaAs/AlxGa1-xAs quantum double rings (QDRs) are studied. Our model can be used to calculate the electronic structures of quantum wells, wires, dots, and the single ring. In calculations, the effects due to the different effective masses of electrons and holes in GaAs and AlxGa1-xAs and the valence band mixing are considered. The energy levels of electrons and holes are calculated for different shapes of QDRs. The calculated results are useful in designing and fabricating the interrelated photoelectric devices. The single electron states presented here are useful for the study of the electron correlations and the effects of magnetic fields in QDRs.

Beam measurements using visible synchrotron light at NSLS2 storage ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Weixing, E-mail: chengwx@bnl.gov; Bacha, Bel; Singh, Om

2016-07-27

Visible Synchrotron Light Monitor (SLM) diagnostic beamline has been designed and constructed at NSLS2 storage ring, to characterize the electron beam profile at various machine conditions. Due to the excellent alignment, SLM beamline was able to see the first visible light when beam was circulating the ring for the first turn. The beamline has been commissioned for the past year. Besides a normal CCD camera to monitor the beam profile, streak camera and gated camera are used to measure the longitudinal and transverse profile to understand the beam dynamics. Measurement results from these cameras will be presented in this paper.more » A time correlated single photon counting system (TCSPC) has also been setup to measure the single bunch purity.« less

Switchable single-longitudinal-mode dual-wavelength erbium-doped fiber ring laser based on one polarization-maintaining fiber Bragg grating incorporating saturable absorber and feedback fiber loop

NASA Astrophysics Data System (ADS)

Feng, Suchun; Xu, Ou; Lu, Shaohua; Ning, Tigang; Jian, Shuisheng

2009-06-01

Switchable single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber ring laser based on one polarization-maintaining fiber Bragg grating (PMFBG) is demonstrated. Due to the enhancement of the polarization hole burning (PHB) by the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). The stable SLM operation is guaranteed by a compound-ring cavity and a saturable absorber (SA). The optical signal-to-noise ratio (OSNR) is over 45 dB. The amplitude variation in nearly one and half an hour is less than 0.2 dB.

Analysis of a single ring resonator with 2×2 90-degree multimode waveguide turning couplers

NASA Astrophysics Data System (ADS)

Chiu, C. L.; Liao, Yen-Hsun

2016-02-01

A novel design of a single ring resonator with two low-loss 2×2 90-degree multimode waveguide turning mirror couplers based on a InP structure. The coupling factor of the 2×2 90-degree multimode waveguide turning mirror coupler is inversed for K=0.85 to K=0.15 when one folding is achieved. The 2×2 90-degree turning mirror coupler for K=0.15 is (3/4)Lπ in length. Its length is reduced 3 times than the conventional straight 2×2 multimode waveguide interference coupler (9/4)Lπ in length for K=0.15. The cavity length of the curve waveguide (90-degree arc length) in this ring resonator with two 2×2 90-degree multimode waveguide turning couplers is decreased 1/2 times than with two 2×2 MMI couplers (180-degree arc length). The free spectral range (FSR) is increased 2 times. The output spectral response gets a FSR of 82 GHz for the device and a contrast of 4 dB and FWHM of 0.24 nm for the drop port. The results of numerical analysis calculated by the transfer functions in a single ring resonator are agreement with the experimental results.

In vitro contraction of cytokinetic ring depends on myosin II but not on actin dynamics.

PubMed

Mishra, Mithilesh; Kashiwazaki, Jun; Takagi, Tomoko; Srinivasan, Ramanujam; Huang, Yinyi; Balasubramanian, Mohan K; Mabuchi, Issei

2013-07-01

Cytokinesis in many eukaryotes involves the contraction of an actomyosin-based contractile ring. However, the detailed mechanism of contractile ring contraction is not fully understood. Here, we establish an experimental system to study contraction of the ring to completion in vitro. We show that the contractile ring of permeabilized fission yeast cells undergoes rapid contraction in an ATP- and myosin-II-dependent manner in the absence of other cytoplasmic constituents. Surprisingly, neither actin polymerization nor its disassembly is required for contraction of the contractile ring, although addition of exogenous actin-crosslinking proteins blocks ring contraction. Using contractile rings generated from fission yeast cytokinesis mutants, we show that not all proteins required for assembly of the ring are required for its contraction in vitro. Our work provides the beginnings of the definition of a minimal contraction-competent cytokinetic ring apparatus.

FtsZ rings and helices: physical mechanisms for the dynamic alignment of biopolymers in rod-shaped bacteria.

PubMed

Fischer-Friedrich, Elisabeth; Friedrich, Benjamin M; Gov, Nir S

2012-02-01

In many bacterial species, the protein FtsZ forms a cytoskeletal ring that marks the future division site and scaffolds the division machinery. In rod-shaped bacteria, most frequently membrane-attached FtsZ rings or ring fragments are reported and occasionally helices. By contrast, axial FtsZ clusters have never been reported. In this paper, we investigate theoretically how dynamic FtsZ aggregates align in rod-shaped bacteria. We study systematically different physical mechanisms that affect the alignment of FtsZ polymers using a computational model that relies on autocatalytic aggregation of FtsZ filaments at the membrane. Our study identifies a general tool kit of physical and geometrical mechanisms by which rod-shaped cells align biopolymer aggregates. Our analysis compares the relative impact of each mechanism on the circumferential alignment of FtsZ as observed in rod-shaped bacteria. We determine spontaneous curvature of FtsZ polymers and axial confinement of FtsZ on the membrane as the strongest factors. Including Min oscillations in our model, we find that these stabilize axial and helical clusters on short time scales, but promote the formation of an FtsZ ring at the cell middle at longer times. This effect could provide an explanation to the long standing puzzle of transiently observed oscillating FtsZ helices in Escherichia coli cells prior to cell division.

Study of Osteoclast Adhesion to Cortical Bone Surfaces: A Correlative Microscopy Approach for Concomitant Imaging of Cellular Dynamics and Surface Modifications

PubMed Central

2015-01-01

Bone remodeling relies on the coordinated functioning of osteoblasts, bone-forming cells, and osteoclasts, bone-resorbing cells. The effects of specific chemical and physical bone features on the osteoclast adhesive apparatus, the sealing zone ring, and their relation to resorption functionality are still not well-understood. We designed and implemented a correlative imaging method that enables monitoring of the same area of bone surface by time-lapse light microscopy, electron microscopy, and atomic force microscopy before, during, and after exposure to osteoclasts. We show that sealing zone rings preferentially develop around surface protrusions, with lateral dimensions of several micrometers, and ∼1 μm height. Direct overlay of sealing zone rings onto resorption pits on the bone surface shows that the rings adapt to pit morphology. The correlative procedure presented here is noninvasive and performed under ambient conditions, without the need for sample labeling. It can potentially be applied to study various aspects of cell-matrix interactions. PMID:26682493

Propagation of Electrical Excitation in a Ring of Cardiac Cells: A Computer Simulation Study

NASA Technical Reports Server (NTRS)

Kogan, B. Y.; Karplus, W. J.; Karpoukhin, M. G.; Roizen, I. M.; Chudin, E.; Qu, Z.

1996-01-01

The propagation of electrical excitation in a ring of cells described by the Noble, Beeler-Reuter (BR), Luo-Rudy I (LR I), and third-order simplified (TOS) mathematical models is studied using computer simulation. For each of the models it is shown that after transition from steady-state circulation to quasi-periodicity achieved by shortening the ring length (RL), the action potential duration (APD) restitution curve becomes a double-valued function and is located below the original ( that of an isolated cell) APD restitution curve. The distributions of APD and diastolic interval (DI) along a ring for the entire range of RL corresponding to quasi-periodic oscillations remain periodic with the period slightly different from two RLs. The 'S' shape of the original APD restitution curve determines the appearance of the second steady-state circulation region for short RLs. For all the models and the wide variety of their original APD restitution curves, no transition from quasi-periodicity to chaos was observed.

Mass production of shaped particles through vortex ring freezing

PubMed Central

An, Duo; Warning, Alex; Yancey, Kenneth G.; Chang, Chun-Ti; Kern, Vanessa R.; Datta, Ashim K.; Steen, Paul H.; Luo, Dan; Ma, Minglin

2016-01-01

A vortex ring is a torus-shaped fluidic vortex. During its formation, the fluid experiences a rich variety of intriguing geometrical intermediates from spherical to toroidal. Here we show that these constantly changing intermediates can be ‘frozen' at controlled time points into particles with various unusual and unprecedented shapes. These novel vortex ring-derived particles, are mass-produced by employing a simple and inexpensive electrospraying technique, with their sizes well controlled from hundreds of microns to millimetres. Guided further by theoretical analyses and a laminar multiphase fluid flow simulation, we show that this freezing approach is applicable to a broad range of materials from organic polysaccharides to inorganic nanoparticles. We demonstrate the unique advantages of these vortex ring-derived particles in several applications including cell encapsulation, three-dimensional cell culture, and cell-free protein production. Moreover, compartmentalization and ordered-structures composed of these novel particles are all achieved, creating opportunities to engineer more sophisticated hierarchical materials. PMID:27488831

Nanoscale architecture of the Schizosaccharomyces pombe contractile ring.

PubMed

McDonald, Nathan A; Lind, Abigail L; Smith, Sarah E; Li, Rong; Gould, Kathleen L

2017-09-15

The contractile ring is a complex molecular apparatus which physically divides many eukaryotic cells. Despite knowledge of its protein composition, the molecular architecture of the ring is not known. Here we have applied super-resolution microscopy and FRET to determine the nanoscale spatial organization of Schizosaccharomyces pombe contractile ring components relative to the plasma membrane. Similar to other membrane-tethered actin structures, we find proteins localize in specific layers relative to the membrane. The most membrane-proximal layer (0-80 nm) is composed of membrane-binding scaffolds, formin, and the tail of the essential myosin-II. An intermediate layer (80-160 nm) consists of a network of cytokinesis accessory proteins as well as multiple signaling components which influence cell division. Farthest from the membrane (160-350 nm) we find F-actin, the motor domains of myosins, and a major F-actin crosslinker. Circumferentially within the ring, multiple proteins proximal to the membrane form clusters of different sizes, while components farther from the membrane are uniformly distributed. This comprehensive organizational map provides a framework for understanding contractile ring function.

Nanoscale architecture of the Schizosaccharomyces pombe contractile ring

PubMed Central

McDonald, Nathan A; Lind, Abigail L; Smith, Sarah E; Li, Rong

2017-01-01

The contractile ring is a complex molecular apparatus which physically divides many eukaryotic cells. Despite knowledge of its protein composition, the molecular architecture of the ring is not known. Here we have applied super-resolution microscopy and FRET to determine the nanoscale spatial organization of Schizosaccharomyces pombe contractile ring components relative to the plasma membrane. Similar to other membrane-tethered actin structures, we find proteins localize in specific layers relative to the membrane. The most membrane-proximal layer (0–80 nm) is composed of membrane-binding scaffolds, formin, and the tail of the essential myosin-II. An intermediate layer (80–160 nm) consists of a network of cytokinesis accessory proteins as well as multiple signaling components which influence cell division. Farthest from the membrane (160–350 nm) we find F-actin, the motor domains of myosins, and a major F-actin crosslinker. Circumferentially within the ring, multiple proteins proximal to the membrane form clusters of different sizes, while components farther from the membrane are uniformly distributed. This comprehensive organizational map provides a framework for understanding contractile ring function. PMID:28914606

Crystallographic structure of the turbine C-ring from spinach chloroplast F-ATP synthase

PubMed Central

Balakrishna, Asha Manikkoth; Seelert, Holger; Marx, Sven-Hendric; Dencher, Norbert A.; Grüber, Gerhard

2014-01-01

In eukaryotic and prokaryotic cells, F-ATP synthases provide energy through the synthesis of ATP. The chloroplast F-ATP synthase (CF1FO-ATP synthase) of plants is integrated into the thylakoid membrane via its FO-domain subunits a, b, b’ and c. Subunit c with a stoichiometry of 14 and subunit a form the gate for H+-pumping, enabling the coupling of electrochemical energy with ATP synthesis in the F1 sector. Here we report the crystallization and structure determination of the c14-ring of subunit c of the CF1FO-ATP synthase from spinach chloroplasts. The crystals belonged to space group C2, with unit-cell parameters a=144.420, b=99.295, c=123.51 Å, and β=104.34° and diffracted to 4.5 Å resolution. Each c-ring contains 14 monomers in the asymmetric unit. The length of the c-ring is 60.32 Å, with an outer ring diameter 52.30 Å and an inner ring width of 40 Å. PMID:27919036

H. PYLORI INFECTION, ENDOSCOPIC, HISTOLOGICAL ASPECTS AND CELL PROLIFERATION IN THE GASTRIC MUCOSA OF PATIENTS SUBMITTED TO ROUX-EN-Y GASTRIC BYPASS WITH CONTENTION RING: a cross sectional endoscopic and immunohistochemical study.

PubMed

Nogueira, Thiago De Bortoli; Artigiani, Ricardo; Herani, Benedito; Waisberg, Jaques

2016-01-01

Morbid obesity treatment through vertical gastroplasty Roux-en-Y gastric bypass initially used a contention ring. However, this technique may create conditions to the development of potentially malign alterations in the gastric mucosa. Although effective and previously performed in large scale, this technique needs to be better evaluated in long-term studies regarding alterations caused in the gastric mucosa. To analyze the preoperative and postoperative endoscopic, histological and cell proliferation findings in the gastric antrum and body mucosa of patients submitted to the Roux-en-Y gastric bypass with a contention ring. We retrospectively evaluated all patients submitted to Roux-en-Y gastric bypass with a contention ring with more than 60 months of postoperative follow-up. We compared the preoperative (gastric antrum and body) and postoperative (gastric pouch) gastric mucosa endoscopic findings, cell proliferation index and H. pylori prevalence. We evaluated cell proliferation through Ki-67 antibody immunohistochemical expression. In the study period, 33 patients were operated with the Roux-en-Y gastric bypass using a contention ring. We found a chronic gastritis rate of 69.7% in the preoperative period (gastric antrum and body) and 84.8% in the postoperative (gastric pouch). H. pylori was present in 18.2% of patients in the preoperative period (gastric antrum and body) and in 57.5% in the postoperative (gastric pouch). Preoperative cell proliferation index was 18.1% in the gastric antrum and 16.2% in the gastric body, and 23.8% in the postoperative gastric pouch. The postoperative cell proliferation index in the gastric pouch was significantly higher (P=0.001) than in the preoperative gastric antrum and body. Higher cell proliferation index and chronic gastritis intensity were significantly associated to H. pylori presence (P=0.001 and P=0.02, respectively). After Roux-en-Y gastric bypass with contention ring, there was a higher chronic gastritis incidence and higher cell proliferation index in the gastric pouch than in the preoperative gastric antrum and body. Mucosa inflammation intensity and cell proliferation index in the postoperative gastric pouch were associated to H. pylori presence and were higher than those found in the preoperative gastric antrum and body mucosa.

Deployable Fresnel Rings

NASA Technical Reports Server (NTRS)

Kennedy, Timothy F.; Fink, Patrick W.; Chu, Andrew W.; Lin, Gregory Y.

2014-01-01

Deployable Fresnel rings (DFRs) significantly enhance the realizable gain of an antenna. This innovation is intended to be used in combination with another antenna element, as the DFR itself acts as a focusing or microwave lens element for a primary antenna. This method is completely passive, and is also completely wireless in that it requires neither a cable, nor a connector from the antenna port of the primary antenna to the DFR. The technology improves upon the previous NASA technology called a Tri-Sector Deployable Array Antenna in at least three critical aspects. In contrast to the previous technology, this innovation requires no connector, cable, or other physical interface to the primary communication radio or sensor device. The achievable improvement in terms of antenna gain is significantly higher than has been achieved with the previous technology. Also, where previous embodiments of the Tri-Sector antenna have been constructed with combinations of conventional (e.g., printed circuit board) and conductive fabric materials, this innovation is realized using only conductive and non-conductive fabric (i.e., "e-textile") materials, with the possible exception of a spring-like deployment ring. Conceptually, a DFR operates by canceling the out-of-phase radiation at a plane by insertion of a conducting ring or rings of a specific size and distance from the source antenna, defined by Fresnel zones. Design of DFRs follow similar procedures to those outlined for conventional Fresnel zone rings. Gain enhancement using a single ring is verified experimentally and through computational simulation. The experimental test setup involves a microstrip patch antenna that is directly behind a single-ring DFR and is radiating towards a second microstrip patch antenna. The first patch antenna and DFR are shown. At 2.42 GHz, the DFR improves the transmit antenna gain by 8.6 dB, as shown in Figure 2, relative to the wireless link without the DFR. A figure illustrates the relative strength of power coupling between the first and second microstrip antennas with and without the DFR. Typically, a DFR is designed for use at a particular frequency; however, testing of a DFR indicated a relatively wide operational bandwidth of approximately 8.2%. Wider bandwidth operation and multi-band operation are anticipated by extending the known art of conventional Fresnel rings to the DFRs. Increasing the number of rings used to construct a DFR antenna increases the gain, with the upper bound limited often by the largest practical dimensions that can be tolerated for a given application. The maximum theoretical improvement in gain for a single ring is 9.5 dB. Experimental results are within 0.9 dB of this theoretical value. Adding rings increases gain, and theoretically, improvements of 10 to 13 dB above that of the primary antenna gain can be achieved with two- and three-ring versions.

Passive Vibration Control of Airborne Equipment using a Circular Steel Ring

NASA Technical Reports Server (NTRS)

Ellison, Joseph; Ahmadi, Goodarz; Kehoe, Mike

1997-01-01

Vibration isolation is needed to protect avionics equipment from adverse aircraft vibration environments. Passive isolation is the simplest means to achieve this goal. The system used here consists of a circular steel ring with a lump mass on top and exposed to base excitation. Sinusoidal and filtered zero-mean Gaussian white noise are used to excite the structure and the acceleration response spectra at the top of the ring are computed. An experiment is performed to identify the natural frequencies and modal damping of the circular ring. Comparison is made between the analytical and experimental results and good agreement is observed. The ring response is also evaluated with a concentrated mass attached to the top of the ring. The effectiveness of the ring in isolating the equipment from base excitation is studied. The acceleration response spectra of a single degree of freedom system attached to the top of the ring are evaluated and the results are compared with those exposed directly to the base excitation. It is shown that a properly designed ring could effectively protect the avionics from possible damaging excitation levels.

Synthesis and activity of novel analogs of hemiasterlin as inhibitors of tubulin polymerization: modification of the A segment.

PubMed

Yamashita, Ayako; Norton, Emily B; Kaplan, Joshua A; Niu, Chuan; Loganzo, Frank; Hernandez, Richard; Beyer, Carl F; Annable, Tami; Musto, Sylvia; Discafani, Carolyn; Zask, Arie; Ayral-Kaloustian, Semiramis

2004-11-01

Analogs of hemiasterlin (1) and HTI-286 (2), which contain various aromatic rings in the A segment, were synthesized as potential inhibitors of tubulin polymerization. The structure-activity relationships related to stereo- and regio-chemical effects of substituents on the aromatic ring in the A segment were studied. Analogs, which carry a meta-substituted phenyl ring in the A segment show comparable activity for inhibition of tubulin polymerization to 2, as well as in the cell proliferation assay using KB cells containing P-glycoprotein, compared to those of 1 and 2.

Histopathological, Molecular, and Genetic Profile of Hereditary Diffuse Gastric Cancer: Current Knowledge and Challenges for the Future.

PubMed

van der Post, Rachel S; Gullo, Irene; Oliveira, Carla; Tang, Laura H; Grabsch, Heike I; O'Donovan, Maria; Fitzgerald, Rebecca C; van Krieken, Han; Carneiro, Fátima

Familial clustering is seen in 10 % of gastric cancer cases and approximately 1-3 % of gastric cancer arises in the setting of hereditary diffuse gastric cancer (HDGC). In families with HDGC, gastric cancer presents at young age. HDGC is predominantly caused by germline mutations in CDH1 and in a minority by mutations in other genes, including CTNNA1. Early stage HDGC is characterized by a few, up to dozens of intramucosal foci of signet ring cell carcinoma and its precursor lesions. These include in situ signet ring cell carcinoma and pagetoid spread of signet ring cells. Advanced HDGC presents as poorly cohesive/diffuse type carcinoma, normally with very few typical signet ring cells, and has a poor prognosis. Currently, it is unknown which factors drive the progression towards aggressive disease, but it is clear that most intramucosal lesions will not have such progression.Immunohistochemical profile of early and advanced HDGC is often characterized by abnormal E-cadherin immunoexpression, including absent or reduced membranous expression, as well as "dotted" or cytoplasmic expression. However, membranous expression of E-cadherin does not exclude HDGC. Intramucosal HDGC (pT1a) presents with an "indolent" phenotype, characterized by typical signet ring cells without immunoexpression of Ki-67 and p53, while advanced carcinomas (pT > 1) display an "aggressive" phenotype with pleomorphic cells, that are immunoreactive for Ki-67 and p53. These features show that the IHC profile is different between intramucosal and more advanced HDGC, providing evidence of phenotypic heterogeneity, and may help to define predictive biomarkers of progression from indolent to aggressive, widely invasive carcinomas.

Design of a dual linear polarization antenna using split ring resonators at X-band

NASA Astrophysics Data System (ADS)

Ahmed, Sadiq; Chandra, Madhukar

2017-11-01

Dual linear polarization microstrip antenna configurations are very suitable for high-performance satellites, wireless communication and radar applications. This paper presents a new method to improve the co-cross polarization discrimination (XPD) for dual linear polarized microstrip antennas at 10 GHz. For this, three various configurations of a dual linear polarization antenna utilizing metamaterial unit cells are shown. In the first layout, the microstrip patch antenna is loaded with two pairs of spiral ring resonators, in the second model, a split ring resonator is placed between two microstrip feed lines, and in the third design, a complementary split ring resonators are etched in the ground plane. This work has two primary goals: the first is related to the addition of metamaterial unit cells to the antenna structure which permits compensation for an asymmetric current distribution flow on the microstrip antenna and thus yields a symmetrical current distribution on it. This compensation leads to an important enhancement in the XPD in comparison to a conventional dual linear polarized microstrip patch antenna. The simulation reveals an improvement of 7.9, 8.8, and 4 dB in the E and H planes for the three designs, respectively, in the XPD as compared to the conventional dual linear polarized patch antenna. The second objective of this paper is to present the characteristics and performances of the designs of the spiral ring resonator (S-RR), split ring resonator (SRR), and complementary split ring resonator (CSRR) metamaterial unit cells. The simulations are evaluated using the commercial full-wave simulator, Ansoft High-Frequency Structure Simulator (HFSS).

Efficient second-harmonic conversion of CW single-frequency Nd:YAG laser light by frequency locking to a monolithic ring frequency doubler

NASA Technical Reports Server (NTRS)

Gerstenberger, D. C.; Tye, G. E.; Wallace, R. W.

1991-01-01

Efficient second-harmonic conversion of the 1064-nm output of a diode-pumped CW single-frequency Nd:YAG laser to 532 nm was obtained by frequency locking the laser to a monolithic ring resonator constructed of magnesium-oxide-doped lithium niobate. The conversion efficiency from the fundamental to the second harmonic was 65 percent. Two hundred milliwatts of CW single-frequency 532-nm light were produced from 310 mW of power of 1064-nm light. This represents a conversion efficiency of 20 percent from the 1-W diode laser used to pump the Nd:YAG laser to single-frequency 532-nm output. No signs of degradation were observed for over 500 h of operation.

The Polycomb proteins RING1B and EZH2 repress the tumoral pro-inflammatory function in metastasizing primary cutaneous squamous cell carcinoma.

PubMed

Hernández-Ruiz, Eugenia; Toll, Agustí; García-Diez, Irene; Andrades, Evelyn; Ferrandiz-Pulido, Carla; Masferrer, Emili; Yébenes, Mireia; Jaka, Ane; Gimeno, Javier; Gimeno, Ramón; García-Patos, Vicenç; Pujol, Ramón M; Hernández-Muñoz, Inmaculada

2018-03-08

Cutaneous squamous cell carcinoma (cSCC) is the second most common malignancy in humans and approximately 5% metastasize, usually to regional lymph nodes. Epigenetic regulation of gene expression may allow tumoral cells to acquire new functions in order to escape from the primary tumor. The aim of this study was to investigate the expression and function of proteins of the Polycomb family of epigenetic regulators in the metastatic process of cSCC. A higher expression of RING1B and EZH2 was detected by immunohistochemistry in a series of primary cSCC tumors that metastasized (MSCCs) when compared with non-metastasizing cSCCs (non-MSCCs). Stable downregulation of RING1B and EZH2 in cSCC cells results in enhanced expression of inflammatory cytokines and activation of the NF-κB signaling pathway. Accordingly, non-MSCCs display higher levels of membranous pS176-inhibitor of NF-kB kinase, and their stroma is enriched in neutrophils and eosinophils when compared with MSCCs. In vitro, hematopoietic cells exhibit a substantial migratory response to supernatants from Polycomb-depleted cSCC cells. Altogether, these data indicate that RING1B and EZH2 repress the innate inflammatory cSCC function and impair tumor immunosurveillance and suggest that patients with high-risk cSCCs could benefit from clinical therapies addressed to harness the immune response.

Quantum oscillation and the Aharonov-Bohm effect in a multiply connected normal-conductor loop

NASA Astrophysics Data System (ADS)

Takai, Daisuke; Ohta, Kuniichi

1994-12-01

The magnetostatic and electrostatic Aharonov-Bohm (AB) effects in multiply connected normal-conductor rings are studied. A previously developed model of a single mesoscopic ring is generalized to include an arbitrary number of rings, and the oscillatory behavior of the total transmission coefficients for the serially connected N (N is equal to integer) rings are derived as a function of the magnetic flux threading each ring and as a function of the electrostatic potential applied to the rings. It is shown that quantum oscillation of multiple rings exhibits greater variety of behavior than in periodic superlattices. We investigate the influence of the scattering at a junction and the number of atoms in the ring in both magnetostatic and electrostatic oscillation of multiring systems. For the electrostatic AB effects, when scattering occurs at the junctions between the connecting wire and the ring, the conductance in the AB oscillation is modified to an N-1 peaked shape. It is shown that this oscillatory behavior is greatly influenced by the number of atoms in the ring and is controlled by the electrostatic potential or magnetic flux that is applied to the ring. We discuss the behavior of the quantum oscillations upon varying the number of connected rings and the number of minibands.

Single-frequency operation of diode-pumped 2 microm Q-switched Tm:YAG laser injection seeded by monolithic nonplanar ring laser.

PubMed

Gao, Chunqing; Lin, Zhifeng; Gao, Mingwei; Zhang, Yunshan; Zhu, Lingni; Wang, Ran; Zheng, Yan

2010-05-20

We present a diode-pumped, 2mum single-frequency Q-switched Tm:YAG laser. The Q-switched laser is injection seeded by a monolithic Tm:YAG nonplanar ring oscillator with the ramp-hold-fire technique. The output energy of the 2mum single-frequency Q-switched pulse is 2.23mJ, with a pulse width of 290ns and a repetition rate of 200Hz. From the heterodyne beating measurement, the frequency difference between the seed laser and the Q-switched laser is determined to be 37.66MHz, with a half-width of the symmetric spectrum of about 2 MHz.

Oscillatory persistent currents in self-assembled quantum rings.

PubMed

Kleemans, N A J M; Bominaar-Silkens, I M A; Fomin, V M; Gladilin, V N; Granados, D; Taboada, A G; García, J M; Offermans, P; Zeitler, U; Christianen, P C M; Maan, J C; Devreese, J T; Koenraad, P M

2007-10-05

We report the direct measurement of the persistent current carried by a single electron by means of magnetization experiments on self-assembled InAs/GaAs quantum rings. We measured the first Aharonov-Bohm oscillation at a field of 14 T, in perfect agreement with our model based on the structural properties determined by cross-sectional scanning tunneling microscopy measurements. The observed oscillation magnitude of the magnetic moment per electron is remarkably large for the topology of our nanostructures, which are singly connected and exhibit a pronounced shape asymmetry.

Fractional Dynamics of Single File Diffusion in Dusty Plasma Ring

NASA Astrophysics Data System (ADS)

Muniandy, S. V.; Chew, W. X.; Asgari, H.; Wong, C. S.; Lim, S. C.

2011-11-01

Single file diffusion (SFD) refers to the constrained motion of particles in quasi-one-dimensional channel such that the particles are unable to pass each other. Possible SFD of charged dust confined in biharmonic annular potential well with screened Coulomb interaction is investigated. Transition from normal diffusion to anomalous sub-diffusion behaviors is observed. Deviation from SFD's mean square displacement scaling behavior of 1/2-exponent may occur in strongly interacting systems. A phenomenological model based on fractional Langevin equation is proposed to account for the anomalous SFD behavior in dusty plasma ring.

Phosphorescence Tuning through Heavy Atom Placement in Unsymmetrical Difluoroboron β-Diketonate Materials.

PubMed

Liu, Tiandong; Zhang, Guoqing; Evans, Ruffin E; Trindle, Carl O; Altun, Zikri; DeRosa, Christopher A; Wang, Fang; Zhuang, Meng; Fraser, Cassandra L

2018-02-06

Difluoroboron β-diketonates (BF 2 bdks) show both fluorescence (F) and room-temperature phosphorescence (RTP) when confined to a rigid matrix, such as poly(lactic acid). These materials have been utilized as optical oxygen sensors (e.g., in tumors, wounds, and cells). Spectral features include charge transfer (CT) from the major aromatic donor to the dioxaborine acceptor. A series of naphthyl-phenyl dyes (BF 2 nbm) (1-6) were prepared to test heavy-atom placement effects. The BF 2 nbm dye (1) was substituted with Br on naphthyl (2), phenyl (3), or both rings (4) to tailor the fluorescence/phosphorescence ratio and RTP lifetime-important features for designing O 2 sensing dyes by means of the heavy atom effect. Computational studies identify the naphthyl ring as the major donor. Thus, Br substitution on the naphthyl ring produced greater effects on the optical properties, such as increased RTP intensity and decreased RTP lifetime compared to phenyl substitution. However, for electron-donating piperidyl-phenyl dyes (5), the phenyl aromatic is the major donor. As a result, Br substitution on the naphthyl ring (6) did not alter the optical properties significantly. Experimental data and computational modeling show the importance of Br position. The S 1 and T 1 states are described by two singly occupied MOs (SOMOs). When both of these SOMOs have substantial amplitude on the heavy atom, passage from S 1 to T 1 and emission from T 1 to S 0 are both favored. This shortens the excited-state lifetimes and enhances phosphorescence. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lis1 regulates dynein by sterically blocking its mechanochemical cycle

PubMed Central

Toropova, Katerina; Zou, Sirui; Roberts, Anthony J; Redwine, William B; Goodman, Brian S; Reck-Peterson, Samara L; Leschziner, Andres E

2014-01-01

Regulation of cytoplasmic dynein's motor activity is essential for diverse eukaryotic functions, including cell division, intracellular transport, and brain development. The dynein regulator Lis1 is known to keep dynein bound to microtubules; however, how this is accomplished mechanistically remains unknown. We have used three-dimensional electron microscopy, single-molecule imaging, biochemistry, and in vivo assays to help establish this mechanism. The three-dimensional structure of the dynein–Lis1 complex shows that binding of Lis1 to dynein's AAA+ ring sterically prevents dynein's main mechanical element, the ‘linker’, from completing its normal conformational cycle. Single-molecule experiments show that eliminating this block by shortening the linker to a point where it can physically bypass Lis1 renders single dynein motors insensitive to regulation by Lis1. Our data reveal that Lis1 keeps dynein in a persistent microtubule-bound state by directly blocking the progression of its mechanochemical cycle. DOI: http://dx.doi.org/10.7554/eLife.03372.001 PMID:25380312

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eriksson, Mikael

Not very long ago, the 3{sup rd} generation storage ring technology was judged as mature. Most of the 3{sup rd} generation storage rings used the Double-Bend Achromat (DBA) or Triple-Bend Achromat (TBA) concepts. It was however a well-known fact that increasing the number of magnet cells in the rings is a powerful way of decreasing the electron beam emittance and thus the source brilliance, but at the penalty of increasing the size and cost of the rings. Preserving the Dynamic Aperture (DA) in the rings became also an issue when increasing the number of magnet cells. The Multi-Bend Achromat (MBA)more » concept, including a miniaturization of the ring elements, has now drastically changed the picture. The MBA rings, now in construction or being planned, offer orders of magnitudes higher brilliance than rings of conventional designs. Several light sources around the world are now implementing or planning to implement this MBA concept. This article touches on the science drivers for higher brilliance. We will then describe the MBA concept with its advantages as well as its challenges. A short survey of the MBA activity around the world will also be presented. The author apologies for focusing on the MAX IV project regarding technical solutions. This is motivated by that MAX IV is the facility he knows best and it might be regarded as a fore-runner for the MBA concept.« less

A Compact Trench-Assisted Multi-Orbital-Angular-Momentum Multi-Ring Fiber for Ultrahigh-Density Space-Division Multiplexing (19 Rings × 22 Modes)

PubMed Central

Li, Shuhui; Wang, Jian

2014-01-01

We present a compact (130 μm cladding diameter) trench-assisted multi-orbital-angular-momentum (OAM) multi-ring fiber with 19 rings each supporting 22 modes with 18 OAM ones. Using the high-contrast-index ring and trench designs, the trench-assisted multi-OAM multi-ring fiber (TA-MOMRF) features both low-level inter-mode crosstalk and inter-ring crosstalk within a wide wavelength range (1520 to 1630 nm), which can potentially enable Pbit/s total transmission capacity and hundreds bit/s/Hz spectral efficiency in a single TA-MOMRF. Moreover, the effective refractive index difference of even and odd fiber eigenmodes induced by the ellipticity of ring and fiber bending and their impacts on the purity of OAM mode and mode coupling/crosstalk are analyzed. It is found that high-order OAM modes show preferable tolerance to the ring ellipticity and fiber bending. The designed fiber offers favorable tolerance to both small ellipticity of ring (<−22 dB crosstalk under an ellipticity of 0.5%) and small bend radius (<−20 dB crosstalk under a bend radius of 2 cm). PMID:24458159

Reduced Intensity Chemotherapy and Radiation Therapy Before Donor Stem Cell Transplant in Treating Patients With Hematologic Malignancies

ClinicalTrials.gov

2018-05-10

Acute Myeloid Leukemia; Acute Myeloid Leukemia in Remission; Aplastic Anemia; Chronic Myelomonocytic Leukemia; Hodgkin Lymphoma; Indolent Non-Hodgkin Lymphoma; Malignant Neoplasm; Myelodysplastic Syndrome; Myeloproliferative Neoplasm; Plasma Cell Myeloma; Refractory Anemia; Refractory Anemia With Excess Blasts; Refractory Anemia With Ring Sideroblasts; Refractory Cytopenia With Multilineage Dysplasia; Refractory Cytopenia With Multilineage Dysplasia and Ring Sideroblasts

1.5 W high efficiency and tunable single-longitudinal-mode Ho:YLF ring laser based on Faraday effect.

PubMed

Wu, Jing; Ju, Youlun; Dai, Tongyu; Yao, Baoquan; Wang, Yuezhu

2017-10-30

We demonstrated an efficient and tunable single-longitudinal-mode Ho:YLF ring laser based on Faraday effect for application to measure atmospheric carbon dioxide (CO 2 ). Single-longitudinal-mode power at 2051.65 nm achieved 528 mW with the slope efficiency of 39.5% and the M 2 factor of 1.07, and the tunable range of about 178 GHz was obtained by inserting a Fabry-Perot (F-P) etalon with the thickness of 0.5 mm. In addition, the maximum single-longitudinal-mode power reached 1.5 W with the injected power of 528 mW at 2051.65 nm by master oscillator power amplifier (MOPA) technique. High efficiency and tunable single-longitudinal-mode based on Faraday effect around 2 μm has not been reported yet to the best of our knowledge.

Surgical anatomy and morphologic variations of umbilical structures.

PubMed

Fathi, Amir H; Soltanian, Hooman; Saber, Alan A

2012-05-01

The umbilicus is the main access route to the abdominal cavity in laparoscopic surgeries. However, its anatomical configuration is rarely studied in the surgical and anatomical literature. With introduction of laparoendoscopic single-site surgery and considering the significant number of primary and postoperative umbilical hernias, we felt the necessity to comprehensively study the umbilical structures and analyze their protective function against hernias. Twenty-four embalmed cadavers were studied in the anatomy laboratory of Case Western Reserve University. Round hepatic, median and medial ligaments, umbilical ring, umbilical and umbilicovesicular fasciae, and pattern of attachment to the ring were dissected and measured. Mean age was 82.1 years, ranging between 56 and 96 years, with a male-to-female ratio of 1.4:1. Ninety-two per cent was white and 8 per cent black adults. According to shape and attachment pattern of ligaments, umbilical ring is classified into five types. Hernia incidence was 25 per cent. All hernia cases lacked the umbilical fascia and the round hepatic ligament was not attached to the inferior border of the ring. The umbilical ring and its morphologic relation with adjacent ligaments are described and classified into five types. In contrary to sparse existing literature, we propose that umbilical fascia is continuation and condensation of umbilicovesicular rather than transversalis fascia. It was absent in cadavers forming conjoined median and medial ligaments with a single insertion site to the ring. Round ligament insertion to the inferior border of the ring provides another protective factor. These two protective measures were absent in all the observed umbilical hernias.

Polyalkoxybenzenes from plants. 5. Parsley seed extract in synthesis of azapodophyllotoxins featuring strong tubulin destabilizing activity in the sea urchin embryo and cell culture assays.

PubMed

Semenova, Marina N; Kiselyov, Alex S; Tsyganov, Dmitry V; Konyushkin, Leonid D; Firgang, Sergei I; Semenov, Roman V; Malyshev, Oleg R; Raihstat, Mikhail M; Fuchs, Fabian; Stielow, Anne; Lantow, Margareta; Philchenkov, Alex A; Zavelevich, Michael P; Zefirov, Nikolay S; Kuznetsov, Sergei A; Semenov, Victor V

2011-10-27

A series of 4-azapodophyllotoxin derivatives with modified rings B and E have been synthesized using allylpolyalkoxybenzenes from parsley seed oil. The targeted molecules were evaluated in vivo in a phenotypic sea urchin embryo assay for antimitotic and tubulin destabilizing activity. The most active compounds identified by the in vivo sea urchin embryo assay featured myristicin-derived ring E. These molecules were determined to be more potent than podophyllotoxin. Cytotoxic effects of selected molecules were further confirmed and evaluated by conventional assays with A549 and Jurkat human leukemic T-cell lines including cell growth inhibition, cell cycle arrest, cellular microtubule disruption, and induction of apoptosis. The ring B modification yielded 6-OMe substituted molecule as the most active compound. Finally, in Jurkat cells, compound induced caspase-dependent apoptosis mediated by the apical caspases-2 and -9 and not caspase-8, implying the involvement of the intrinsic caspase-9-dependent apoptotic pathway.

Chaperonin polymers in archaea: The cytoskeleton of prokaryotes?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trent, J.D.; Kagawa, H.K.; Zaluzec, N.J.

Chaperonins are protein complexes that play a critical role in folding nascent polypeptides under normal conditions and refolding damaged proteins under stress conditions. In all organisms these complexes are composed of evolutionarily conserved 60-kDa proteins arranged in double-ring structures with between 7 and 9 protein subunits per ring. These double ring structures are assumed to be the functional units in vivo, although they have never been observed inside cells. Here the authors show that the purified chaperonin from the hyperthermophilic archaeon Sulfolobus shibatae, which is closely related to chaperonins in eukaryotes, has a double ring structure at low concentrations (0.1more » mg/ml), but at more physiological concentrations, the rings stack end to end to form polymers. The polymers are stable at physiological temperatures (75 C) and closely resemble structures observed inside unfixed S. shibatae cells. The authors suggest that in vivo chaperonin activity may be regulated by polymerization and that chaperonin polymers may act as a cytoskeleton-like structure in archaea and bacteria.« less

Chaperonin Polymers in Archaea: The Cytoskeleton of Prokaryotes?

DOE R&D Accomplishments Database

Trent, J. D.; Kagawa, H. K.; Zaluzec, N. J.

1997-07-01

Chaperonins are protein complexes that play a critical role in folding nascent polypeptides under normal conditions and refolding damaged proteins under stress conditions. In all organisms these complexes are composed of evolutionarily conserved 60-kDa proteins arranged in double-ring structures with between 7 and 9 protein subunits per ring. These double ring structures are assumed to be the functional units in vivo, although they have never been observed inside cells. Here the authors show that the purified chaperonin from the hyperthermophilic archaeon Sulfolobus shibatae, which is closely related to chaperonins in eukaryotes, has a double ring structure at low concentrations (0.1 mg/ml), but at more physiological concentrations, the rings stack end to end to form polymers. The polymers are stable at physiological temperatures (75 C) and closely resemble structures observed inside unfixed S. shibatae cells. The authors suggest that in vivo chaperonin activity may be regulated by polymerization and that chaperonin polymers may act as a cytoskeleton-like structure in archaea and bacteria.

Spin wave spectra in perpendicularly magnetized permalloy rings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, X.; Ding, J.; Adeyeye, A. O., E-mail: eleaao@nus.edu.sg

2015-03-16

The dynamic behavior of perpendicularly magnetized permalloy circular rings is systematically investigated as a function of film thickness using broadband field modulated ferromagnetic resonance spectroscopy. We observed the splitting of one spin wave mode into a family of dense resonance peaks for the rings, which is markedly different from the single mode observed for continuous films of the same thickness. As the excitation frequency is increased, the mode family observed for the rings gradually converges into one mode. With the increase in the film thickness, a sparser spectrum of modes is observed. Our experimental results are in qualitative agreement withmore » the dynamic micromagnetic simulations.« less

Wheat germ-based protein libraries for the functional characterisation of the Arabidopsis E2 ubiquitin conjugating enzymes and the RING-type E3 ubiquitin ligase enzymes.

PubMed

Ramadan, Abdelaziz; Nemoto, Keiichirou; Seki, Motoaki; Shinozaki, Kazuo; Takeda, Hiroyuki; Takahashi, Hirotaka; Sawasaki, Tatsuya

2015-11-10

Protein ubiquitination is a ubiquitous mechanism in eukaryotes. In Arabidopsis, ubiquitin modification is mainly mediated by two ubiquitin activating enzymes (E1s), 37 ubiquitin conjugating enzymes (E2s), and more than 1300 predicted ubiquitin ligase enzymes (E3s), of which ~470 are RING-type E3s. A large proportion of the RING E3's gene products have yet to be characterised in vitro, likely because of the laborious work involved in large-scale cDNA cloning and protein expression, purification, and characterisation. In addition, several E2s, which might be necessary for the activity of certain E3 ligases, cannot be expressed by Escherichia coli or cultured insect cells and, therefore, remain uncharacterised. Using the RIKEN Arabidopsis full-length cDNA library (RAFL) with the 'split-primer' PCR method and a wheat germ cell-free system, we established protein libraries of Arabidopsis E2 and RING E3 enzymes. We expressed 35 Arabidopsis E2s including six enzymes that have not been previously expressed, and 204 RING proteins, most of which had not been functionally characterised. Thioester assays using dithiothreitol (DTT) showed DTT-sensitive ubiquitin thioester formation for all E2s expressed. In expression assays of RING proteins, 31 proteins showed high molecular smears, which are probably the result of their functional activity. The activities of another 27 RING proteins were evaluated with AtUBC10 and/or a group of different E2s. All the 27 RING E3s tested showed ubiquitin ligase activity, including 17 RING E3s. Their activities are reported for the first time. The wheat germ cell-free system used in our study, which is a eukaryotic expression system and more closely resembles the endogenous expression of plant proteins, is very suitable for expressing Arabidopsis E2s and RING E3s in their functional form. In addition, the protein libraries described here can be used for further understanding E2-E3 specificities and as platforms for protein-protein interaction screening.

Lightweight acoustic treatments for aerospace applications

NASA Astrophysics Data System (ADS)

Naify, Christina Jeanne

2011-12-01

Increase in the use of composites for aerospace applications has the benefit of decreased structural weight, but at the cost of decreased acoustic performance. Stiff, lightweight structures (such as composites) are traditionally not ideal for acoustic insulation applications because of high transmission loss at low frequencies. A need has thus arisen for effective sound insulation materials for aerospace and automotive applications with low weight addition. Current approaches, such as the addition of mass law dominated materials (foams) also perform poorly when scaled to small thickness and low density. In this dissertation, methods which reduce sound transmission without adding significant weight are investigated. The methods presented are intended to be integrated into currently used lightweight structures such as honeycomb sandwich panels and to cover a wide range of frequencies. Layering gasses of differing acoustic impedances on a panel substantially reduced the amount of sound energy transmitted through the panel with respect to the panel alone or an equivalent-thickness single species gas layer. The additional transmission loss derives from successive impedance mismatches at the interfaces between gas layers and the resulting inefficient energy transfer. Attachment of additional gas layers increased the transmission loss (TL) by as much as 17 dB at high (>1 kHz) frequencies. The location and ordering of the gasses with respect to the panel were important factors in determining the magnitude of the total TL. Theoretical analysis using a transfer matrix method was used to calculate the frequency dependence of sound transmission for the different configurations tested. The method accurately predicted the relative increases in TL observed with the addition of different gas layer configurations. To address low-frequency sound insulation, membrane-type locally resonant acoustic materials (LRAM) were fabricated, characterized, and analyzed to understand their acoustic response. Acoustic metamaterials with negative dynamic mass density have been shown to demonstrate a significant (5x) increase in TL over mass law predictions for a narrow band (100Hz) at low frequencies (100--1000Hz). The peak TL frequency can be tuned to specific values by varying the membrane and mass properties. TL magnitude as a function of frequency was measured for variations of the mass magnitude and membrane tension using an impedance tube setup. The dynamic properties of membranes constructed from different materials and thicknesses were measured and compared to the results of coupled field acoustic-structural finite element analysis (FEA) modeling to understand the role of tension and element quality factor. To better comprehend the mechanism(s) responsible for the TL peak, a laser vibrometer was used to map the out-of-plane dynamic response of the structure under acoustic loading at discrete frequencies. Negative dynamic mass was experimentally demonstrated at the peak TL frequency. The scale-up of the acoustic metamaterial structure was explored by examining the behavior of multiple elements arranged in arrays. Single membranes were stretched over rigid frame supports and masses were attached to the center of each divided cell. TL behavior was measured for multiple configurations with different magnitudes of mass distributed across each of the cell membranes in the array resulting in a multi-peak TL profile. To better understand scale-up issues, the effect of the frame structure compliance was evaluated, and more compliant frames resulted in a reduction in TL peak frequency bandwidth. In addition, displacement measurements of frames and membranes were performed using a laser vibrometer. The measured TL of the multi-celled structure was compared with TL behavior predicted by FEA to understand the role of non-uniform mass distribution and frame compliance. TL of membrane-type LRAM with added ring masses was analyzed using both finite element analysis and experimental techniques. The addition of a ring mass to the structure either increased the bandwidth of the TL peak, or introduced multiple peaks, depending on the number of rings, the distribution of mass between the center and ring masses, and radii of the rings. FEA was used to predict TL behavior of several ring configurations, and TL for these configurations was measured to validate the model predictions. Finally, FEA was used to predict the mode shapes of the structure under single-frequency excitation to understand the mechanisms responsible for the TL peaks.

An Equatorial Contractile Mechanism Drives Cell Elongation but not Cell Division

PubMed Central

Denker, Elsa; Bhattachan, Punit; Deng, Wei; Mathiesen, Birthe T.; Jiang, Di

2014-01-01

Cell shape changes and proliferation are two fundamental strategies for morphogenesis in animal development. During embryogenesis of the simple chordate Ciona intestinalis, elongation of individual notochord cells constitutes a crucial stage of notochord growth, which contributes to the establishment of the larval body plan. The mechanism of cell elongation is elusive. Here we show that although notochord cells do not divide, they use a cytokinesis-like actomyosin mechanism to drive cell elongation. The actomyosin network forming at the equator of each notochord cell includes phosphorylated myosin regulatory light chain, α-actinin, cofilin, tropomyosin, and talin. We demonstrate that cofilin and α-actinin are two crucial components for cell elongation. Cortical flow contributes to the assembly of the actomyosin ring. Similar to cytokinetic cells, membrane blebs that cause local contractions form at the basal cortex next to the equator and participate in force generation. We present a model in which the cooperation of equatorial actomyosin ring-based constriction and bleb-associated contractions at the basal cortex promotes cell elongation. Our results demonstrate that a cytokinesis-like contractile mechanism is co-opted in a completely different developmental scenario to achieve cell shape change instead of cell division. We discuss the occurrences of actomyosin rings aside from cell division, suggesting that circumferential contraction is an evolutionally conserved mechanism to drive cell or tissue elongation. PMID:24503569

Dispersion relations for circular single and double dusty plasma chains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tkachenko, D. V.; Misko, V. R.; Sheridan, T. E.

2011-10-15

We derive dispersion relations for a system of identical particles confined in a two-dimensional annular harmonic well and which interact through a Yukawa potential, e.g., a dusty plasma ring. When the particles are in a single chain (i.e., a one-dimensional ring), we find a longitudinal acoustic mode and a transverse optical mode which show approximate agreement with the dispersion relation for a straight configuration for large radii of the ring. When the radius decreases, the dispersion relations modify: there appears an anticrossing of the modes near the crossing point resulting in a frequency gap between the lower and upper branchesmore » of the modified dispersion relations. For the double chain (i.e., a two-dimensional zigzag configuration), the dispersion relation has four branches: longitudinal acoustic and optical and transverse acoustic and optical.« less

Dispersion relations for circular single and double dusty plasma chains

NASA Astrophysics Data System (ADS)

Tkachenko, D. V.; Sheridan, T. E.; Misko, V. R.

2011-10-01

We derive dispersion relations for a system of identical particles confined in a two-dimensional annular harmonic well and which interact through a Yukawa potential, e.g., a dusty plasma ring. When the particles are in a single chain (i.e., a one-dimensional ring), we find a longitudinal acoustic mode and a transverse optical mode which show approximate agreement with the dispersion relation for a straight configuration for large radii of the ring. When the radius decreases, the dispersion relations modify: there appears an anticrossing of the modes near the crossing point resulting in a frequency gap between the lower and upper branches of the modified dispersion relations. For the double chain (i.e., a two-dimensional zigzag configuration), the dispersion relation has four branches: longitudinal acoustic and optical and transverse acoustic and optical.

Rings of membrane sterols surround the openings of vesicles and fenestrae, in capillary endothelium.

PubMed

Simionescu, N; Lupu, F; Simionescu, M

1983-11-01

We investigated the distribution of sterols in the cell membrane of microvascular endothelium (mouse pancreas, diaphragm, brain, heart, lung, kidney, thyroid, adrenal, and liver) with the polyene antibiotic filipin, which reportedly has binding specificity for free 3-beta-hydroxysterols. In some experiments, concomitantly, cell-surface anionic sites were detected with cationized ferritin. Vessels were perfused in situ with PBS, followed by light fixation and filipin administration for 10 to 60 min. Tissues were further processed for thin-section and freeze-fracture electron microscopy. Short exposure (10 min) to filipin-glutaraldehyde solution resulted in the initial appearance, on many areas, of rings of characteristic filipin-sterol complexes within the rim surrounding stomata of most plasmalemmal vesicles, transendothelial channels, and fenestrae. Such rings were absent from the rims of the large openings of the sinusoid endothelium (liver, adrenal), coated pits and phagocytic vacuoles. After longer exposure (30-60 min), filipin-sterol complexes labeled randomly the rest of plasma membrane (except for coated pits, and partially the interstrand areas of junctions), and also marked most plasmalemmal vesicles. These peristomal rings of sterols were displayed mostly on the P face, and, at their full development, consisted of 6-8 units around a vesicle stoma, and 10-12 units around a fenestra. At their level, the intramembranous particles and the cell surface anionic sites were virtually excluded. Peristomal rings of sterols were also detected on the plasma membrane of pericytes and smooth muscle cells of the microvascular wall, which otherwise were poorly labeled with filipin-sterol complexes as compared to endothelial plasmalemma. It is presumed that the peristomal rings of cholesterol may represent important contributors to the local transient stabilization of plasma membrane and to the phase separation between cell membrane and vesicle membrane at a certain stage of their fusion/fission process.

Comparison of radiofrequency body coils for MRI at 3 Tesla: a simulation study using parallel transmission on various anatomical targets

PubMed Central

Wu, Xiaoping; Zhang, Xiaotong; Tian, Jinfeng; Schmitter, Sebastian; Hanna, Brian; Strupp, John; Pfeuffer, Josef; Hamm, Michael; Wang, Dingxin; Nistler, Juergen; He, Bin; Vaughan, J. Thomas; Ugurbil, Kamil; Van de Moortele, Pierre-Francois

2015-01-01

The performance of multichannel transmit coil layouts and parallel transmission (pTx) radiofrequency (RF) pulse design was evaluated with respect to transmit B1 (B1+) homogeneity and Specific Absorption Rate (SAR) at 3 Tesla for a whole body coil. Five specific coils were modeled and compared: a 32-rung birdcage body coil (driven either in a fixed quadrature mode or a two-channel transmit mode), two single-ring stripline arrays (with either 8 or 16 elements), and two multi-ring stripline arrays (with 2 or 3 identical rings, stacked in the z-axis and each comprising eight azimuthally distributed elements). Three anatomical targets were considered, each defined by a 3D volume representative of a meaningful region of interest (ROI) in routine clinical applications. For a given anatomical target, global or local SAR controlled pTx pulses were designed to homogenize RF excitation within the ROI. At the B1+ homogeneity achieved by the quadrature driven birdcage design, pTx pulses with multichannel transmit coils achieved up to ~8 fold reduction in local and global SAR. When used for imaging head and cervical spine or imaging thoracic spine, the double-ring array outperformed all coils including the single-ring arrays. While the advantage of the double-ring array became much less pronounced for pelvic imaging with a substantially larger ROI, the pTx approach still provided significant gains over the quadrature birdcage coil. For all design scenarios, using the 3-ring array did not necessarily improve the RF performance. Our results suggest that pTx pulses with multichannel transmit coils can reduce local and global SAR substantially for body coils while attaining improved B1+ homogeneity, particularly for a “z-stacked” double-ring design with coil elements arranged on two transaxial rings. PMID:26332290

Monlithic nonplanar ring oscillator and method

NASA Technical Reports Server (NTRS)

Nilsson, Alan C. (Inventor); Byer, Robert L. (Inventor)

1991-01-01

A monolithic nonplanar ring oscillator having an optically isotropic solid-state laser body for propagating laser radiation about a nonplanar ring path internal to the laser body is disclosed. The monolithic laser body is configured to produce a 2N reflection nonplanar ring light path, where N is an integer greater than or equal to 2, comprising 2N-1 total internal reflections and one reflection at a coupler in a single round trip. Undirectional traveling wave oscillation of the laser is induced by the geometry of the nonplanar ring path together with the effect of an applied magnetic field and partial polarizer characteristics of the oblique reflection from the coupler. The 6-reflection nonplanar ring oscillator makes possible otpimal unidirectional oscillation (low loss for the oscillating direction of propagation and, simultaneously high loss for the nonoscillating direction of propagation) in monolithic NPROs using materials with index of refraction smaller than the square root of 3, for example, laser glass.

New Morphometric Measurements of Peak-Ring Basins on Mercury and the Moon: Results from the Mercury Laser Altimeter and Lunar Orbiter Laser Altimeter

NASA Technical Reports Server (NTRS)

Baker, David M. H.; Head, James W.; Prockter, Louise M.; Fassett, Caleb I.; Neumann, Gregory A.; Smith, David E.; Solomon, Sean C.; Zuber, Maria T.; Oberst, Juergen; Preusker, Frank;

Analysis of reliability for multi-ring interconnection of RPR networks

NASA Astrophysics Data System (ADS)

Liu, Jia; Jin, Depeng; Zeng, Lieguang; Li, Yong

2008-11-01

In this paper, the reliability and MTTF (Mean Time to Failure) for multi-ring RPR (Resilient Packet Ring) are calculated on the conditions of single-link failures, double-link failures and no failure, respectively. The parameters such as the total number of stations N, the number of the sub-rings R, and the distribution of Ni which represents the number of the stations in the i-th sub-ring (1<=i<=R) are contained in the formulas. The relationship between the value of the reliability/MTTF and the parameters N, R and Ni is analyzed. The result shows that reliability/MTTF of the RPR multi-rings is increasing while the variance of Ni is decreasing. It is also proved that the value of the reliability/MTTF is maximum when Ni=Nj ( i ≠j and 1<=i, j<=R) by using Lagrange multipliers method, i.e. the condition of the optimal reliability of multi-ring RPR is satisfied when var(Ni) =0.

Synthesis of novel ring-contracted artemisinin dimers with potent anticancer activities.

PubMed

Zhang, Ning; Yu, Zhimei; Yang, Xiaohong; Hu, Ping; He, Yun

2018-04-25

Artemisinin is a potential anticancer agent with an interesting trioxane sesquiterpene structure. In order to improve the biological activity and metabolic stability of artemisinin, a series of novel ring-contracted artemisinin dimers were synthesized. These dimers were evaluated by MTT assay against six cancer cell lines. Most of the dimmers exhibited improved antiproliferative activities over artemisinin. Especially, compound 8b showed the most pronounced anti-cancer activity for PC12 cancer cells with an IC 50 value of 1.56 μM. Thus, PC12 cancer cells were used to further investigate the mechanism of antiproliferation for this series of compounds. Compound 8b arrested cell cycle at G1 phase and induced cell apoptosis via up-regulation of Bad, Bax, caspase-3 and caspase-9 protein expressions while inhibiting the expression of Bcl-xL. The present studies are the first to synthesize the ring-contracted artemisinin as dimers and show that these dimers have potent anti-tumor activities against several cancer cell lines. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Selective enhancement of Selényi rings induced by the cross-correlation between the interfaces of a two-dimensional randomly rough dielectric film

NASA Astrophysics Data System (ADS)

Banon, J.-P.; Hetland, Ø. S.; Simonsen, I.

2018-02-01

By the use of both perturbative and non-perturbative solutions of the reduced Rayleigh equation, we present a detailed study of the scattering of light from two-dimensional weakly rough dielectric films. It is shown that for several rough film configurations, Selényi interference rings exist in the diffusely scattered light. For film systems supported by dielectric substrates where only one of the two interfaces of the film is weakly rough and the other planar, Selényi interference rings are observed at angular positions that can be determined from simple phase arguments. For such single-rough-interface films, we find and explain by a single scattering model that the contrast in the interference patterns is better when the top interface of the film (the interface facing the incident light) is rough than when the bottom interface is rough. When both film interfaces are rough, Selényi interference rings exist but a potential cross-correlation of the two rough interfaces of the film can be used to selectively enhance some of the interference rings while others are attenuated and might even disappear. This feature may in principle be used in determining the correlation properties of interfaces of films that otherwise would be difficult to access.

Hydromechanical transmission with compound planetary assembly

DOEpatents

Orshansky, Jr., deceased, Elias; Weseloh, William E.

1980-01-01

A power transmission having three distinct ranges: (1) hydrostatic, (2) simple power-split hydromechanical, and (3) compound power-split hydromechanical. A single compound planetary assembly has two sun gears, two ring gears, and a single carrier with two sets of elongated planet gears. The two sun gears may be identical in size, and the two ring gears may be identical in size. A speed-varying module in driving relationship to the first sun gear is clutchable, in turn, to (1) the input shaft and (2) the second sun gear. The speed-varying means may comprise a pair of hydraulic units hydraulically interconnected so that one serves as a pump while the other serves as a motor and vice versa, one of the units having a variable stroke and being the one clutchable to either the input shaft or to the second sun gear. The other unit, which may have a fixed stroke, is connected in driving relation to the first sun gear. A brake grounds the carrier in the first range and in reverse and causes drive to be delivered to the output shaft through the first ring gear in a hydrostatic mode, the first ring gear being rigidly connected to the output shaft. The input shaft is also clutchable to the second ring gear of the compound planetary assembly.

Permanent magnet design for high-speed superconducting bearings

DOEpatents

Hull, John R.; Uherka, Kenneth L.; Abdoud, Robert G.

1996-01-01

A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing.

Perylenetetracarboxylic anhydride as a precursor of fluorescent carbon nanoonion rings.

PubMed

Baldoví, Herme G; Herance, José Raul; Manuel Víctor, Víctor; Alvaro, Mercedes; Garcia, Hermenegildo

2015-08-07

Thermal annealing at 400 °C of perylenetetracarboxylic anhydride in low molecular mass PEG gives rise to the formation of well defined nanoobjects of 2.5 nm height and size distribution from 10 to 65 nm (average 40 nm) after purification of the raw mixture with silicagel chromatography. TEM reveals that the flat nanoobjects are constituted of concentric graphenic rings (0.34 nm interlayer distance). The morphology of the nanoparticles resembles onion rings of nanometric dimensions (nanoonion rings C-NOR). C-NOR particles have an excitation dependent emission with λem from 430 to 570 nm and a maximum emission quantum yield of 0.49. C-NOR particles can be internalized into Hep3B human hepatoma cells as determined by confocal fluorescence microscopy and are remarkably biocompatible affecting slightly cell viability according to the MTT test.

3D Model of Cytokinetic Contractile Ring Assembly: Node-Mediated and Backup Pathways

NASA Astrophysics Data System (ADS)

Bidone, Tamara; Vavylonis, Dimitrios

Cytokinetic ring assembly in model organism fission yeast is a dynamic process, involving condensation of a network of actin filaments and myosin motors bound to the cell membrane through cortical nodes. A 3D computational model of ring assembly illustrates how the combined activities of myosin motors, filament crosslinkers and actin turnover lead to robust ring formation [Bidone et al. Biophys. J, 2014]. We modeled the importance of the physical properties of node movement along the cell membrane and of myosin recruitment to nodes. Experiments by D. Zhang (Temasek Life Sciences) show that tethering of the cortical endoplasmic reticulum (ER) to the plasma membrane modulates the speed of node condensation and the degree of node clumping. We captured the trend observed in these experiments by changes in the node drag coefficient and initial node distribution in simulations PM. The model predicted that reducing crosslinking activities in ER tethering mutants with faster node speed enhances actomyosin clumping. We developed a model of how tilted and/or misplaced rings assemble in cells that lack the node structural component anillin-like Mid1 and thus fail to recruit myosin II to nodes independently of actin. If actin-dependent binding of diffusive myosin to the cortex is incorporated into the model, it generates progressively elongating cortical actomyosin strands with fluctuating actin bundles at the tails. These stands often close into a ring, similar to observations by the group of J.Q. Wu (The Ohio State University). NIH R01GM098430.

A New Dual-Frequency Liquid Crystal Lens with Ring-and-Pie Electrodes and a Driving Scheme to Prevent Disclination Lines and Improve Recovery Time

PubMed Central

Kao, Yung-Yuan; Chao, Paul C.-P.

2011-01-01

A new liquid crystal lens design is proposed to improve the recovery time with a ring-and-pie electrode pattern through a suitable driving scheme and using dual-frequency liquid crystals (DFLC) MLC-2048. Compared with the conventional single hole-type liquid crystal lens, this new structure of the DFLC lens is composed of only two ITO glasses, one of which is designed with the ring-and-pie pattern. For this device, one can control the orientation of liquid crystal directors via a three-stage switching procedure on the particularly-designed ring-and-pie electrode pattern. This aims to eliminate the disclination lines, and using different drive frequencies to reduce the recovery time to be less than 5 seconds. The proposed DFLC lens is shown effective in reducing recovery time, and then serves well as a potential device in places of the conventional lenses with fixed focus lengths and the conventional LC lens with a single circular-hole electrode pattern. PMID:22163906

A node organization in the actomyosin contractile ring generates tension and aids stability

PubMed Central

Thiyagarajan, Sathish; Wang, Shuyuan; O’Shaughnessy, Ben

2017-01-01

During cytokinesis, a contractile actomyosin ring constricts and divides the cell in two. How the ring marshals actomyosin forces to generate tension is not settled. Recently, a superresolution microscopy study of the fission yeast ring revealed that myosins and formins that nucleate actin filaments colocalize in plasma membrane-anchored complexes called nodes in the constricting ring. The nodes move bidirectionally around the ring. Here we construct and analyze a coarse-grained mathematical model of the fission yeast ring to explore essential consequences of the recently discovered ring ultrastructure. The model reproduces experimentally measured values of ring tension, explains why nodes move bidirectionally, and shows that tension is generated by myosin pulling on barbed-end-anchored actin filaments in a stochastic sliding-filament mechanism. This mechanism is not based on an ordered sarcomeric organization. We show that the ring is vulnerable to intrinsic contractile instabilities, and protection from these instabilities and organizational homeostasis require both component turnover and anchoring of components to the plasma membrane. PMID:28954859

The ring vaccination trial: a novel cluster randomised controlled trial design to evaluate vaccine efficacy and effectiveness during outbreaks, with special reference to Ebola.

PubMed

2015-07-27

A World Health Organization expert meeting on Ebola vaccines proposed urgent safety and efficacy studies in response to the outbreak in West Africa. One approach to communicable disease control is ring vaccination of individuals at high risk of infection due to their social or geographical connection to a known case. This paper describes the protocol for a novel cluster randomised controlled trial design which uses ring vaccination.In the Ebola ça suffit ring vaccination trial, rings are randomised 1:1 to (a) immediate vaccination of eligible adults with single dose vaccination or (b) vaccination delayed by 21 days. Vaccine efficacy against disease is assessed in participants over equivalent periods from the day of randomisation. Secondary objectives include vaccine effectiveness at the level of the ring, and incidence of serious adverse events. Ring vaccination trials are adaptive, can be run until disease elimination, allow interim analysis, and can go dormant during inter-epidemic periods. © Ebola ça suffit ring vaccination trial consortium 2015.

Primary Signet Ring Cell Carcinoma of Rectum Diagnosed by Boring Biopsy in Combination with Endoscopic Mucosal Resection.

PubMed

Hirata, Yoshito; Kanno, Keishi; Kishikawa, Nobusuke; Tomoda, Shinji; Kimura, Kazuki; Kobayashi, Tomoki; Miyamori, Daisuke; Otani, Yuichiro; Mizooka, Masafumi; Arihiro, Koji; Oka, Shiro; Tanaka, Shinji; Tazuma, Susumu

2018-01-01

A 46-year-old man with severe back pain visited our hospital. Magnetic resonance imaging revealed extensive bone metastasis and rectal wall thickness. Colonoscopy revealed circumferential stenosis with edematous mucosa, suggesting colon cancer. However, histological findings of biopsy specimens revealed inflammatory cells but no malignant cells. The patient underwent endoscopic ultrasound, which demonstrated edematous wall thickness without destruction of the normal layer structure. After unsuccessful detection of neoplastic cells by boring biopsies, we performed endoscopic mucosal resection followed by boring biopsies that finally revealed signet ring cell carcinoma. Herein, we present a case and provide a review of the literature.

Protein Equilibration through Somatic Ring Canals in Drosophila

PubMed Central

McLean, Peter F.; Cooley, Lynn

2013-01-01

Although intercellular bridges resulting from incomplete cytokinesis were discovered in somatic Drosophila tissues decades ago, the impact of these structures on intercellular communication and tissue biology is largely unknown. In this work, we demonstrate that the ~250 nm diameter somatic ring canals permit diffusion of cytoplasmic contents between connected cells and across mitotic clone boundaries, and enable the equilibration of protein between transcriptionally mosaic follicle cells in the Drosophila ovary. We obtained similar, though more restricted, results in the larval imaginal discs. Our work illustrates the lack of cytoplasmic autonomy in these tissues and suggests a role for somatic ring canals in promoting homogeneous protein expression within the tissue. PMID:23704373

Metro-access integrated network based on optical OFDMA with dynamic sub-carrier allocation and power distribution.

PubMed

Zhang, Chongfu; Zhang, Qiongli; Chen, Chen; Jiang, Ning; Liu, Deming; Qiu, Kun; Liu, Shuang; Wu, Baojian

2013-01-28

We propose and demonstrate a novel optical orthogonal frequency-division multiple access (OFDMA)-based metro-access integrated network with dynamic resource allocation. It consists of a single fiber OFDMA ring and many single fiber OFDMA trees, which transparently integrates metropolitan area networks with optical access networks. The single fiber OFDMA ring connects the core network and the central nodes (CNs), the CNs are on demand reconfigurable and use multiple orthogonal sub-carriers to realize parallel data transmission and dynamic resource allocation, meanwhile, they can also implement flexible power distribution. The remote nodes (RNs) distributed in the user side are connected by the single fiber OFDMA trees with the corresponding CN. The obtained results indicate that our proposed metro-access integrated network is feasible and the power distribution is agile.

Reconfiguration of the multiwavelength operation of optical fiber ring lasers by the modifiable intra-cavity induced losses of an in-fiber tip probe modal Michelson interferometer

NASA Astrophysics Data System (ADS)

Salceda-Delgado, G.; Martinez-Rios, A.; Sierra-Hernandez, J. M.; Rodríguez-Carreón, V. C.; Toral-Acosta, D.; Selvas-Aguilar, R.; Álvarez-Tamayo, R. I.; Castillo-Guzman, A. A.; Rojas-Laguna, R.

2018-03-01

A straightforward and versatile method for switching from single to different multiwavelength laser emission in ring cavity fiber lasers is proposed and demonstrated experimentally. The method is based on using the changeable interference pattern from an optical fiber modal Michelson interferometer as a wavelength selective filter into the ring cavity laser. The interferometer is constructed using a bi-conical tapered fiber and a single-mode fiber segment, with these being spliced together to form an optical fiber tip probe. When the length of the single-mode fiber piece is modified, the phase difference between the interfering modes of the interferometer causes a change in the interferometer free spectral range. As a consequence, the laser intra-cavity losses lead to gain competition, which allows us to adjust the number of simultaneously generated laser lines. A multiwavelength reconfiguration of the laser from one up to a maximum of eight emission lines was obtained, with a maximum SNR of around 47 dBm.

Intra-annual variability of anatomical structure and δ13C values within tree rings of spruce and pine in alpine, temperate and boreal Europe

PubMed Central

Vaganov, Eugene A.; Skomarkova, Marina V.; Knohl, Alexander; Brand, Willi A.; Roscher, Christiane

2009-01-01

Tree-ring width, wood density, anatomical structure and 13C/12C ratios expressed as δ13C-values of whole wood of Picea abies were investigated for trees growing in closed canopy forest stands. Samples were collected from the alpine Renon site in North Italy, the lowland Hainich site in Central Germany and the boreal Flakaliden site in North Sweden. In addition, Pinus cembra was studied at the alpine site and Pinus sylvestris at the boreal site. The density profiles of tree rings were measured using the DENDRO-2003 densitometer, δ13C was measured using high-resolution laser-ablation-combustion-gas chromatography-infra-red mass spectrometry and anatomical characteristics of tree rings (tracheid diameter, cell-wall thickness, cell-wall area and cell-lumen area) were measured using an image analyzer. Based on long-term statistics, climatic variables, such as temperature, precipitation, solar radiation and vapor pressure deficit, explained <20% of the variation in tree-ring width and wood density over consecutive years, while 29–58% of the variation in tree-ring width were explained by autocorrelation between tree rings. An intensive study of tree rings between 1999 and 2003 revealed that tree ring width and δ13C-values of whole wood were significantly correlated with length of the growing season, net radiation and vapor pressure deficit. The δ13C-values were not correlated with precipitation or temperature. A highly significant correlation was also found between δ13C of the early wood of one year and the late wood of the previous year, indicating a carry-over effect of the growing conditions of the previous season on current wood production. This latter effect may explain the high autocorrelation of long-term tree-ring statistics. The pattern, however, was complex, showing stepwise decreases as well as stepwise increases in the δ13C between late wood and early wood. The results are interpreted in the context of the biochemistry of wood formation and its linkage to storage products. It is clear that the relations between δ13C and tree-ring width and climate are multi-factorial in seasonal climates. PMID:19653008

­Back-to-back mechanisms drive actomyosin ring closure during Drosophila embryo cleavage

PubMed Central

2016-01-01

Contraction of actomyosin rings during cytokinesis is typically attributed to actin filaments sliding toward each other via Myosin-2 motor activity. However, rings constrict in some cells in the absence of Myosin-2 activity. Thus, ring closure uses Myosin-2–dependent and –independent mechanisms. But what the Myosin-2–independent mechanisms are, and to what extent they are sufficient to drive closure, remains unclear. During cleavage in Drosophila melanogaster embryos, actomyosin rings constrict in two sequential and mechanistically distinct phases. We show that these phases differ in constriction speed and are genetically and pharmacologically separable. Further, Myosin-2 activity is required for slow constriction in “phase 1” but is largely dispensable for fast constriction in “phase 2,” and F-actin disassembly is only required for fast constriction in phase 2. Switching from phase 1 to phase 2 seemingly relies on the spatial organization of F-actin as controlled by Cofilin, Anillin, and Septin. Our work shows that fly embryos present a singular opportunity to compare separable ring constriction mechanisms, with varying Myosin-2 dependencies, in one cell type and in vivo. PMID:27799369

Acoustic radiation force optical coherence elastography using vibro-acoustography

NASA Astrophysics Data System (ADS)

Qu, Yueqiao (.; Ma, Teng; Li, Rui; Qi, Wenjuan; Zhu, Jiang; He, Youmin; Shung, K. K.; Zhou, Qifa; Chen, Zhongping

2015-03-01

High-resolution elasticity mapping of tissue biomechanical properties is crucial in early detection of many diseases. We report a method of acoustic radiation force optical coherence elastography (ARF-OCE) based on the methods of vibroacoustography, which uses a dual-ring ultrasonic transducer in order to excite a highly localized 3-D field. The single element transducer introduced previously in our ARF imaging has low depth resolution because the ARF is difficult to discriminate along the entire ultrasound propagation path. The novel dual-ring approach takes advantage of two overlapping acoustic fields and a few-hundred-Hertz difference in the signal frequencies of the two unmodulated confocal ring transducers in order to confine the acoustic stress field within a smaller volume. This frequency difference is the resulting "beating" frequency of the system. The frequency modulation of the transducers has been validated by comparing the dual ring ARF-OCE measurement to that of the single ring using a homogeneous silicone phantom. We have compared and analyzed the phantom resonance frequency to show the feasibility of our approach. We also show phantom images of the ARF-OCE based vibro-acoustography method and map out its acoustic stress region. We concluded that the dual-ring transducer is able to better localize the excitation to a smaller region to induce a focused force, which allows for highly selective excitation of small regions. The beat-frequency elastography method has great potential to achieve high-resolution elastography for ophthalmology and cardiovascular applications.

Real-time and label-free ring-resonator monitoring of solid-phase recombinase polymerase amplification.

PubMed

Sabaté Del Río, Jonathan; Steylaerts, Tim; Henry, Olivier Y F; Bienstman, Peter; Stakenborg, Tim; Van Roy, Wim; O'Sullivan, Ciara K

2015-11-15

In this work we present the use of a silicon-on-insulator (SOI) chip featuring an array of 64 optical ring resonators used as refractive index sensors for real-time and label-free DNA detection. Single ring functionalisation was achieved using a click reaction after precise nanolitre spotting of specific hexynyl-terminated DNA capture probes to link to an azido-silanised chip surface. To demonstrate detectability using the ring resonators and to optimise conditions for solid-phase amplification, hybridisation between short 25-mer single stranded DNA (ssDNA) fragments and a complementary capture probe immobilised on the surface of the ring resonators was carried out and detected through the shift in the resonant wavelength. Using the optimised conditions demonstrated via the solid-phase hybridisation, a 144-bp double stranded DNA (dsDNA) was then detected directly using recombinase and polymerase proteins through on-chip target amplification and solid-phase elongation of immobilised forward primers on specific rings, at a constant temperature of 37°C and in less than 60min, achieving a limit of detection of 7.8·10(-13)M (6·10(5) copies in 50µL). The use of an automatic liquid handler injection instrument connected to an integrated resealable chip interface (RCI) allowed programmable multiple injection protocols. Air plugs between different solutions were introduced to prevent intermixing and a proportional-integral-derivative (PID) temperature controller minimised temperature based drifts. Published by Elsevier B.V.

Microsecond kinetics in model single- and double-stranded amylose polymers.

PubMed

Sattelle, Benedict M; Almond, Andrew

2014-05-07

Amylose, a component of starch with increasing biotechnological significance, is a linear glucose polysaccharide that self-organizes into single- and double-helical assemblies. Starch granule packing, gelation and inclusion-complex formation result from finely balanced macromolecular kinetics that have eluded precise experimental quantification. Here, graphics processing unit (GPU) accelerated multi-microsecond aqueous simulations are employed to explore conformational kinetics in model single- and double-stranded amylose. The all-atom dynamics concur with prior X-ray and NMR data while surprising and previously overlooked microsecond helix-coil, glycosidic linkage and pyranose ring exchange are hypothesized. In a dodecasaccharide, single-helical collapse was correlated with linkages and rings transitioning from their expected syn and (4)C1 chair conformers. The associated microsecond exchange rates were dependent on proximity to the termini and chain length (comparing hexa- and trisaccharides), while kinetic features of dodecasaccharide linkage and ring flexing are proposed to be a good model for polymers. Similar length double-helices were stable on microsecond timescales but the parallel configuration was sturdier than the antiparallel equivalent. In both, tertiary organization restricted local chain dynamics, implying that simulations of single amylose strands cannot be extrapolated to dimers. Unbiased multi-microsecond simulations of amylose are proposed as a valuable route to probing macromolecular kinetics in water, assessing the impact of chemical modifications on helical stability and accelerating the development of new biotechnologies.

Fractional conductance oscillations in quantum rings: wave packet picture of transport in a few-electron system.

PubMed

Chwiej, T; Szafran, B

2013-04-17

We study electron transfer across a two-terminal quantum ring using a time-dependent description of the scattering process. For the considered scattering event the quantum ring is initially charged with one or two electrons, with another electron incident to the ring from the input channel. We study the electron transfer probability (T) as a function of the external magnetic field. We determine the periodicity of T for a varied number of electrons confined within the ring. For that purpose we develop a method to describe the wave packet dynamics for a few electrons participating in the scattering process, taking into full account the electron-electron correlations. We find that electron transfer across the quantum ring initially charged by a single electron acquires a distinct periodicity of half of the magnetic flux quantum (Φ0/2), corresponding to the formation of a transient two-electron state inside the ring. In the case of a three-electron scattering problem with two electrons initially occupying the ring, a period of Φ0/3 for T is formed in the limit of thin channels. The effect of disorder present in the confinement potential of the ring is also discussed.

Climate signals derived from cell anatomy of Scots pine in NE Germany.

PubMed

Liang, Wei; Heinrich, Ingo; Simard, Sonia; Helle, Gerhard; Liñán, Isabel Dorado; Heinken, Thilo

2013-08-01

Tree-ring chronologies of Pinus sylvestris L. from latitudinal and altitudinal limits of the species distribution have been widely used for climate reconstructions, but there are many sites within the temperate climate zone, as is the case in northeastern Germany, at which there is little evidence of a clear climate signal in the chronologies. In this study, we developed long chronologies of several cell structure variables (e.g., average lumen area and cell wall thickness) from P. sylvestris growing in northeastern Germany and investigated the influence of climate on ring widths and cell structure variables. We found significant correlations between cell structure variables and temperature, and between tree-ring width and relative humidity and vapor pressure, respectively, enabling the development of robust reconstructions from temperate sites that have not yet been realized. Moreover, it has been shown that it may not be necessary to detrend chronologies of cell structure variables and thus low-frequency climate signals may be retrieved from longer cell structure chronologies. The relatively extensive resource of archaeological material of P. sylvestris covering approximately the last millennium may now be useful for climate reconstructions in northeastern Germany and other sites in the temperate climate zone.

Morphology and variability of the Titan ringlet and Huygens ringlet edges

NASA Astrophysics Data System (ADS)

Jerousek, Richard G.; Colwell, Joshua E.; Esposito, Larry W.

2011-11-01

We present a forward modeling approach for determining, in part, the ring particle spatial distribution in the vicinity of sharp ring or ringlet edges. Synthetic edge occultation profiles are computed based on a two-parameter particle spatial distribution model. One parameter, h, characterizes the vertical extent of the ring and the other, δ, characterizes the radial scale over which the ring optical depth transitions from the background ring value to zero. We compare our synthetic occultation profiles to high resolution stellar occultation light curves observed by the Cassini Ultraviolet Imaging Spectrograph (UVIS) High Speed Photometer (HSP) for occultations by the Titan ringlet and Huygens ringlet edges. More than 100 stellar occultations of the Huygens ringlet and Titan ringlet edges were studied, comprising 343 independent occultation cuts of the edges of these two ringlets. In 237 of these profiles the measured light-curve was fit well with our two-parameter edge model. Of the remaining edge occultations, 69 contained structure that could only be fit with extremely large values of the ring-plane vertical thickness ( h > 1 km) or by adopting a different model for the radial profile of the ring optical depth. An additional 37 could not be fit by our two-parameter model. Certain occultations at low ring-plane incidence angles as well as occultations nearly tangent to the ring edge allow the direct measurement of the radial scale over which the particle packing varies at the edge of the ringlet. In 24 occultations with these particular viewing geometries, we find a wide variation in the radial scale of the edge. We are able to constrain the vertical extent of the rings at the edge to less than ˜300 m in the 70% of the occultations with appropriate viewing geometry, however tighter constraints could not be placed on h due to the weaker sensitivity of the occultation profile to vertical thickness compared to its sensitivity to δ. Many occultations of a single edge could not be fit to a single value of δ, indicating large temporal or azimuthal variability, although the azimuthal variation in δ with respect to the longitudes of various moons in the system did not show any discernible pattern.

Colocalization of cell division proteins FtsZ and FtsA to cytoskeletal structures in living Escherichia coli cells by using green fluorescent protein

PubMed Central

Ma, Xiaolan; Ehrhardt, David W.; Margolin, William

1996-01-01

In the current model for bacterial cell division, FtsZ protein forms a ring that marks the division plane, creating a cytoskeletal framework for the subsequent action of other proteins such as FtsA. This putative protein complex ultimately generates the division septum. Herein we report that FtsZ and FtsA proteins tagged with green fluorescent protein (GFP) colocalize to division-site ring-like structures in living bacterial cells in a visible space between the segregated nucleoids. Cells with higher levels of FtsZ–GFP or with FtsA–GFP plus excess wild-type FtsZ were inhibited for cell division and often exhibited bright fluorescent spiral tubules that spanned the length of the filamentous cells. This suggests that FtsZ may switch from a septation-competent localized ring to an unlocalized spiral under some conditions and that FtsA can bind to FtsZ in both conformations. FtsZ–GFP also formed nonproductive but localized aggregates at a higher concentration that could represent FtsZ nucleation sites. The general domain structure of FtsZ–GFP resembles that of tubulin, since the C terminus of FtsZ is not required for polymerization but may regulate polymerization state. The N-terminal portion of Rhizobium FtsZ polymerized in Escherichia coli and appeared to copolymerize with E. coli FtsZ, suggesting a degree of interspecies functional conservation. Analysis of several deletions of FtsA–GFP suggests that multiple segments of FtsA are important for its localization to the FtsZ ring. PMID:8917533

Primary signet ring cell carcinoma of the appendix: A rare case report and our 18-year experience

PubMed Central

Ko, Yoon Ho; Jung, Chan-Kwon; Oh, Soon Nam; Kim, Tae Hee; Won, Hye Sung; Kang, Jin Hyoung; Kim, Hyung Jin; Kang, Won Kyung; Oh, Seong Taek; Hong, Young Seon

2008-01-01

Primary adenocarcinoma of the appendix is a rare malignancy that constitutes < 0.5% of all gastrointestinal neoplasms. Moreover, primary signet ring cell carcinoma of the appendix is an exceedingly rare entity. We have encountered 15 cases of primary appendiceal cancer among 3389 patients who underwent appendectomy over the past 18 years. In the present report, we describe a rare case of primary signet ring cell carcinoma of the appendix with ovarian metastases and unresectable peritoneal dissemination occurring in a 67-year-old female patient. She underwent appendectomy and bilateral salpingo-oophorectomy with a laparoscopy procedure. She then received palliative systemic chemotherapy with 12 cycles of oxaliplatin, 5-fluorouracil, and leucovorin (FOLFOX-4). The patient currently is well without progression of disease 12 mo after beginning chemotherapy. PMID:18837098

[Metastatic signet ring cell carcinoma to the breast from stomach].

PubMed

Krichen Makni, S; Abbes, K; Khanfir, A; Frikha, M; Sellami Boudawara, T

2007-09-01

Metastatic tumors in the breast are quite rare and constitute 0.5 to 6% of all breast malignancies. They often occur in a polymetastatic context. The most frequent primitive tumors are lymphoma, leukaemia and malignant melanoma. The gastric origin is seldom reported. We report here the observation of a 40-years woman operated in urgency for an acute abdominal syndrome. A gastric tumor was discovered intraoperatively with ovarian metastasis and peritoneal carcinosis. The pathological examination revealed a gastric signet ring cell carcinoma with an infiltration of the right ovary. Four months later, the patient presented with a lump of the right breast. The histologic examination corresponded to a mammary metastasis by a signet ring cell carcinoma from stomach. The objective of our work is to discuss through this observation the anatomoclinical and evolutionary characteristics of breast metastasis.

Spoof Surface Plasmon Polaritons Power Divider with large Isolation.

PubMed

Zhou, Shiyan; Lin, Jing-Yu; Wong, Sai-Wai; Deng, Fei; Zhu, Lei; Yang, Yang; He, Yejun; Tu, Zhi-Hong

2018-04-13

Periodic corrugated metal structure is designed to support and propagate spoof surface plasmon polaritons (SSPPs) wave in the microwave frequencies. In this paper, firstly a plasmonic waveguide consisting of oval-ring shaped cells is proposed with the performance of high transmission efficiency in a wide frequency range. The coplanar waveguides (CPWs) with 50 Ω impedance are adopted to feed the energies or extract signals at both ends of the plasmonic waveguide. Then a well-isolated power divider is constructed based on the SSPPs waveguides aiming to equally split the energy of the SSPPs wave into two equal parts. The stepped-impedances are co-designed with the three input/output ports of the power divider to achieve the impedance-matching between the SSPPs waveguides and the coplanar waveguides. Besides, a single resistor is placed in the middle of two symmetrical half oval-rings to realize the isolation between the two output ports over the spectrum of 4.5-7.5 GHz. Finally, both plasmonic waveguide and the power divider are fabricated and tested to verify the predicted characteristics.

Venezenin: a new bioactive Annonaceous acetogenin from the bark of Xylopia aromatica.

PubMed

Colman-Saizarbitoria, T; Gu, Z M; Zhao, G X; Zeng, L; Kozlowski, J F; McLaughlin, J L

1995-04-01

Asimicin and a new cytotoxic Annonaceous acetogenin, venezenin [1], were isolated from the bark of Xylopia aromatica by bioactivity-directed fractionation using lethality to brine shrimp. Compound 1 represents an unusual type of C37 Annonaceous acetogenin, lacking either tetrahydrofuran (THF) or epoxide rings and possessing a double bond located two methylenes away from a vicinal diol in the hydrocarbon chain. The structure of 1 was elucidated by 1H- and 13C-nmr, COSY, single-relayed COSY, and by HMBC techniques, and derivatization. Annomontacin 10-one [6] and 18/21-cis-annomontacin-10-one [7], two semi-synthetic mono-THF acetogenins were prepared from 1. These acetogenins showed cytotoxicity, comparable or superior to adriamycin, against three human solid tumor cell lines. Reduction of the 10-keto of 1 to the racemic OH-10 derivative enhanced the bioactivity, as did the conversion of 1 to 6 and 7. Venezenin [1], like other Annonaceous acetogenins, showed inhibition of oxygen uptake by rat liver mitochondria and demonstrated that the THF ring may not be essential to this mode of action.

Mid-infrared surface transmitting and detecting quantum cascade device for gas-sensing

PubMed Central

Harrer, Andreas; Szedlak, Rolf; Schwarz, Benedikt; Moser, Harald; Zederbauer, Tobias; MacFarland, Donald; Detz, Hermann; Andrews, Aaron Maxwell; Schrenk, Werner; Lendl, Bernhard; Strasser, Gottfried

2016-01-01

We present a bi-functional surface emitting and surface detecting mid-infrared device applicable for gas-sensing. A distributed feedback ring quantum cascade laser is monolithically integrated with a detector structured from a bi-functional material for same frequency lasing and detection. The emitted single mode radiation is collimated, back reflected by a flat mirror and detected by the detector element of the sensor. The surface operation mode combined with the low divergence emission of the ring quantum cascade laser enables for long analyte interaction regions spatially separated from the sample surface. The device enables for sensing of gaseous analytes which requires a relatively long interaction region. Our design is suitable for 2D array integration with multiple emission and detection frequencies. Proof of principle measurements with isobutane (2-methylpropane) and propane as gaseous analytes were conducted. Detectable concentration values of 0–70% for propane and 0–90% for isobutane were reached at a laser operation wavelength of 6.5 μm utilizing a 10 cm gas cell in double pass configuration. PMID:26887891

Isometric multimodal photoacoustic microscopy based on optically transparent micro-ring ultrasonic detection.

PubMed

Dong, Biqin; Li, Hao; Zhang, Zhen; Zhang, Kevin; Chen, Siyu; Sun, Cheng; Zhang, Hao F

2015-01-01

Photoacoustic microscopy (PAM) is an attractive imaging tool complementary to established optical microscopic modalities by providing additional molecular specificities through imaging optical absorption contrast. While the development of optical resolution photoacoustic microscopy (ORPAM) offers high lateral resolution, the acoustically-determined axial resolution is limited due to the constraint in ultrasonic detection bandwidth. ORPAM with isometric spatial resolution along both axial and lateral direction is yet to be developed. Although recently developed sophisticated optical illumination and reconstruction methods offer improved axial resolution in ORPAM, the image acquisition procedures are rather complicated, limiting their capabilities for high-speed imaging and being easily integrated with established optical microscopic modalities. Here we report an isometric ORPAM based on an optically transparent micro-ring resonator ultrasonic detector and a commercial inverted microscope platform. Owing to the superior spatial resolution and the ease of integrating our ORPAM with established microscopic modalities, single cell imaging with extrinsic fluorescence staining, intrinsic autofluorescence, and optical absorption can be achieved simultaneously. This technique holds promise to greatly improve the accessibility of PAM to the broader biomedical researchers.

Conductance of closed and open long Aharonov-Bohm-Kondo rings

NASA Astrophysics Data System (ADS)

Shi, Zheng; Komijani, Yashar

2017-02-01

We calculate the finite temperature linear dc conductance of a generic single-impurity Anderson model containing an arbitrary number of Fermi liquid leads, and apply the formalism to closed and open long Aharonov-Bohm-Kondo (ABK) rings. We show that, as with the short ABK ring, there is a contribution to the conductance from the connected four-point Green's function of the conduction electrons. At sufficiently low temperatures this contribution can be eliminated, and the conductance can be expressed as a linear function of the T matrix of the screening channel. For closed rings we show that at temperatures high compared to the Kondo temperature, the conductance behaves differently for temperatures above and below vF/L , where vF is the Fermi velocity and L is the circumference of the ring. For open rings, when the ring arms have both a small transmission and a small reflection, we show from the microscopic model that the ring behaves like a two-path interferometer, and that the Kondo temperature is unaffected by details of the ring. Our findings confirm that ABK rings are potentially useful in the detection of the size of the Kondo screening cloud, the π /2 scattering phase shift from the Kondo singlet, and the suppression of Aharonov-Bohm oscillations due to inelastic scattering.

Assessing resolution in live cell structured illumination microscopy

NASA Astrophysics Data System (ADS)

Pospíšil, Jakub; Fliegel, Karel; Klíma, Miloš

2017-12-01

Structured Illumination Microscopy (SIM) is a powerful super-resolution technique, which is able to enhance the resolution of optical microscope beyond the Abbe diffraction limit. In the last decade, numerous SIM methods that achieve the resolution of 100 nm in the lateral dimension have been developed. The SIM setups with new high-speed cameras and illumination pattern generators allow rapid acquisition of the live specimen. Therefore, SIM is widely used for investigation of the live structures in molecular and live cell biology. Quantitative evaluation of resolution enhancement in a real sample is essential to describe the efficiency of super-resolution microscopy technique. However, measuring the resolution of a live cell sample is a challenging task. Based on our experimental findings, the widely used Fourier ring correlation (FRC) method does not seem to be well suited for measuring the resolution of SIM live cell video sequences. Therefore, the resolution assessing methods based on Fourier spectrum analysis are often used. We introduce a measure based on circular average power spectral density (PSDca) estimated from a single SIM image (one video frame). PSDca describes the distribution of the power of a signal with respect to its spatial frequency. Spatial resolution corresponds to the cut-off frequency in Fourier space. In order to estimate the cut-off frequency from a noisy signal, we use a spectral subtraction method for noise suppression. In the future, this resolution assessment approach might prove useful also for single-molecule localization microscopy (SMLM) live cell imaging.

Circular lasers for telecommunications and rf/photonics applications

NASA Astrophysics Data System (ADS)

Griffel, Giora

2000-04-01

Following a review of ring resonator research in the past decade we shall report a novel bi-level etching technique that permits the use of standard photolithography for coupling to deeply-etched ring resonator structures. The technique is employed to demonstrate InGaAsP laterally- coupled racetrack ring resonators laser with record low threshold currents of 66 mA. The racetrack laser have curved sections of 150 micrometers radius with negligible bending loss. The lasers operate CW single mode up to nearly twice threshold with a 26 dB side-mode-suppression ratio. We shall also present a transfer matrix formalism for the analysis of ring resonator arrays and indicate application examples for flat band filter synthesis.

A novel survivable architecture for hybrid WDM/TDM passive optical networks

NASA Astrophysics Data System (ADS)

Qiu, Yang; Chan, Chun-Kit

2014-02-01

A novel tree-ring survivable architecture, which consists of an organization of a wavelength-division-multiplexing (WDM) tree from optical line terminal (OLT) to remote nodes (RNs) and a time division multiplexing (TDM) ring in each RN, is proposed for hybrid WDM/TDM passive optical networks. By utilizing the cyclic property of arrayed waveguide gratings (AWGs) and the single-ring topology among a group of optical network units (ONUs) in the remote node, not only the feeder and distribution fibers, but also any fiber failures in the RN rings are protected simultaneously. Five-Gbit/s transmissions under both normal working and protection modes were experimentally demonstrated and a traffic restoration time was successfully measured.

Structure of eukaryotic CMG helicase at a replication fork and implications to replisome architecture and origin initiation

PubMed Central

Georgescu, Roxana; Yuan, Zuanning; Bai, Lin; de Luna Almeida Santos, Ruda; Sun, Jingchuan; Zhang, Dan; Yurieva, Olga; Li, Huilin; O’Donnell, Michael E.

2017-01-01

The eukaryotic CMG (Cdc45, Mcm2–7, GINS) helicase consists of the Mcm2–7 hexameric ring along with five accessory factors. The Mcm2–7 heterohexamer, like other hexameric helicases, is shaped like a ring with two tiers, an N-tier ring composed of the N-terminal domains, and a C-tier of C-terminal domains; the C-tier contains the motor. In principle, either tier could translocate ahead of the other during movement on DNA. We have used cryo-EM single-particle 3D reconstruction to solve the structure of CMG in complex with a DNA fork. The duplex stem penetrates into the central channel of the N-tier and the unwound leading single-strand DNA traverses the channel through the N-tier into the C-tier motor, 5′-3′ through CMG. Therefore, the N-tier ring is pushed ahead by the C-tier ring during CMG translocation, opposite the currently accepted polarity. The polarity of the N-tier ahead of the C-tier places the leading Pol ε below CMG and Pol α-primase at the top of CMG at the replication fork. Surprisingly, the new N-tier to C-tier polarity of translocation reveals an unforeseen quality-control mechanism at the origin. Thus, upon assembly of head-to-head CMGs that encircle double-stranded DNA at the origin, the two CMGs must pass one another to leave the origin and both must remodel onto opposite strands of single-stranded DNA to do so. We propose that head-to-head motors may generate energy that underlies initial melting at the origin. PMID:28096349

4-[(E)-(2,4-Difluoro-phen-yl)(hydroxy-imino)meth-yl]piperidinium picrate.

PubMed

Jasinski, Jerry P; Butcher, Ray J; Yathirajan, H S; Mallesha, L; Mohana, K N

2009-09-05

The title compound, C(12)H(15)F(2)N(2)O(+)·C(6)H(2)N(3)O(7) (-), a picrate salt of 4-[(E)-(2,4-difluoro-phen-yl)(hydroxy-imino)meth-yl]piper-idine, crystallizes with two independent mol-ecules in a cation-anion pair in the asymmetric unit. In the cation, a methyl group is tris-ubstituted by hydroxy-imino, piperidin-4-yl and 2,4-difluoro-phenyl groups, the latter of which contains an F atom disordered over two positions in the ring [occupancy ratio 0.631 (4):0.369 (4)]. The mean plane of the hydr-oxy group is in a synclinical conformation nearly orthogonal [N-C-C-C = 72.44 (19)°] to the mean plane of the piperidine ring, which adopts a slightly distorted chair conformation. The dihedral angle between the mean plane of the 2,4-difluoro-phenyl and piperidin-4-yl groups is 60.2 (3)°. In the picrate anion, the mean planes of the two o-NO(2) and single p-NO(2) groups adopt twist angles of 5.7 (2), 25.3 (7) and 8.3 (6)°, respectively, with the attached planar benzene ring. The dihedral angle between the mean planes of the benzene ring in the picrate anion and those in the hydroxy-imino, piperidin-4-yl and 2,4-difluoro-phenyl groups in the cation are 84.9 (7), 78.9 (4) and 65.1 (1)°, respectively. Extensive hydrogen-bond inter-actions occur between the cation-anion pair, which help to establish the crystal packing in the unit cell. This includes dual three-center hydrogen bonds with the piperidin-4-yl group, the phenolate and o-NO(2) O atoms of the picrate anion at different positions in the unit cell, which form separate N-H⋯(O,O) bifurcated inter-molecular hydrogen-bond inter-actions. Also, the hydr-oxy group forms a separate hydrogen bond with a nearby piperidin-4-yl N atom, thus providing two groups of hydrogen bonds, which form an infinite two-dimensional network along (011).

Humidity sensor based on intracavity sensing of fiber ring laser

NASA Astrophysics Data System (ADS)

Shi, Jia; Xu, Wei; Xu, Degang; Wang, Yuye; Zhang, Chao; Yan, Chao; Yan, Dexian; He, Yixin; Tang, Longhuang; Zhang, Weihong; Yao, Jianquan

2017-10-01

A humidity sensor based on the intracavity sensing of a fiber ring laser is proposed and experimentally demonstrated. In the fiber ring laser, a humidity-sensitive fiber-optic multimode interferometer (MMI), fabricated by the single-mode-no-core-single-mode (SNCS) fiber coated with Agarose, works as the wavelength-selective filter for intracavity wavelength-modulated humidity sensing. The experiment shows that the lasing wavelength of the fiber laser has a good linear response to ambient humidity from 35%RH to 95%RH. The humidity sensitivity of -68 pm/%RH is obtained with a narrow 3 dB bandwidth less than 0.09 nm and a high signal-to-noise ratio (SNR)  ˜60 dB. The time response of the sensor has been measured to be as fast as 93 ms. The proposed sensor possesses a good stability and low temperature cross-sensitivity.

Permanent magnet design for high-speed superconducting bearings

DOEpatents

Hull, J.R.; Uherka, K.L.; Abdoud, R.G.

1996-09-10

A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure is disclosed. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing. 9 figs.

Robust gap repair in the contractile ring ensures timely completion of cytokinesis

PubMed Central

Maiato, Helder; Pinto, Inês Mendes; Rubinstein, Boris

2016-01-01

Cytokinesis in animal cells requires the constriction of an actomyosin contractile ring, whose architecture and mechanism remain poorly understood. We use laser microsurgery to explore the biophysical properties of constricting rings in Caenorhabditis elegans embryos. Laser cutting causes rings to snap open. However, instead of disintegrating, ring topology recovers and constriction proceeds. In response to severing, a finite gap forms and is repaired by recruitment of new material in an actin polymerization–dependent manner. An open ring is able to constrict, and rings repair from successive cuts. After gap repair, an increase in constriction velocity allows cytokinesis to complete at the same time as controls. Our analysis demonstrates that tension in the ring increases while net cortical tension at the site of ingression decreases throughout constriction and suggests that cytokinesis is accomplished by contractile modules that assemble and contract autonomously, enabling local repair of the actomyosin network. Consequently, cytokinesis is a highly robust process impervious to discontinuities in contractile ring structure. PMID:27974482

Transparent arrays of silver nanowire rings driven by evaporation of sessile droplets

NASA Astrophysics Data System (ADS)

Wang, Xiaofeng; Kang, Giho; Seong, Baekhoon; Chae, Illkyeong; Teguh Yudistira, Hadi; Lee, Hyungdong; Kim, Hyunggun; Byun, Doyoung

2017-11-01

A coffee-ring pattern can be yielded on the three-phase contact line following evaporation of sessile droplets with suspended insoluble solutes, such as particles, DNA molecules, and mammalian cells. The formation of such coffee-ring, together with their suppression has been applied in printing and coating technologies. We present here an experimental study on the assembly of silver nanowires inside an evaporating droplet of a colloidal suspension. The effects of nanowire length and concentration on coffee-ring formation of the colloidal suspension were investigated. Several sizes of NWs with an aspect ratio between 50 and 1000 were systematically investigated to fabricate coffee-ring patterns. Larger droplets containing shorter nanowires formed clearer ring deposits after evaporation. An order-to-disorder transition of the nanowires’ alignment was found inside the rings. A printing technique with the evaporation process enabled fabrication of arrays of silver nanowire rings. We could manipulate the patterns silver nanowire rings, which might be applied to the transparent and flexible electrode.

Multi-Carotenoids at Physiological Levels Inhibit VEGF-Induced Tube Formation of Endothelial Cells and the Possible Mechanisms of Action Both In Vitro and Ex Vivo.

PubMed

Huang, Chien-Hao; Huang, Chin-Shiu; Hu, Miao-Lin; Chuang, Cheng-Hung

2018-01-01

Carotenoids have been shown to exhibit antiangiogenic activities. Several studies have indicated that carotenoids used in combination were more effective on antioxidation and anticancer actions than carotenoids used singly. However, it is unclear whether multi-carotenoids have antiangiogenic effects. We investigated the effects of multi-carotenoids at physiological plasma levels of Taiwanese (abbreviated as MCT, with a total of 1.4 μM) and Americans (abbreviated as MCA, with a total of 1.8 μM), and of post-supplemental plasma levels (abbreviated as HMC with a total of 3.55 μM) on vascular endothelial growth factor (VEGF)-induced tube formation in human umbilical vein endothelial cells (HUVECs) and rat aortic rings. MCT, MCA, and HMC inhibited VEGF-induced migration, invasion, and tube formation of HUVECs as well as new vessels formation in rat aortic rings. MCT, MCA, and HMC inhibited activities o\\f matrix metalloproteinase (MMP)-2, urokinase plasminogen activator, and phosphorylation of VEGF receptor 2 induced by VEGF. Moreover, MCT, MCA, and HMC significantly upregulated protein expression of tissue inhibitors of MMP-2 and plasminogen activator inhibitor-1. These results demonstrate the antiangiogenic effect of multi-carotenoids both in vitro and ex vivo with possible mechanistic actions involving attenuation of VEGF receptor 2 phosphorylation and extracellular matrix degradation.

Evolution of the Janus-Epimetheus coorbital resonance due to torques from Saturn's rings

NASA Technical Reports Server (NTRS)

Lissauer, J. J.; Goldreich, P.; Tremaine, S.

1985-01-01

The effects of the gravitational interactions between Saturn's rings and the coorbital satellites, Janus and Epimetheus, on the 1:1 horseshoe resonance between these moons is examined. It is shown that the 7:6 resonance of these moons, which presumably maintains the sharp outer edge of the A ring, leads to a rapid tightening of the coorbital lock. The results lead to the prediction that the orbital configuration might evolve from the current horseshoe-type lock to one of tadpole orbits around a single Lagrangian point in about 20 myr.

Methanol clusters (CH3OH)n: putative global minimum-energy structures from model potentials and dispersion-corrected density functional theory.

PubMed

Kazachenko, Sergey; Bulusu, Satya; Thakkar, Ajit J

2013-06-14

Putative global minima are reported for methanol clusters (CH3OH)n with n ≤ 15. The predictions are based on global optimization of three intermolecular potential energy models followed by local optimization and single-point energy calculations using two variants of dispersion-corrected density functional theory. Recurring structural motifs include folded and/or twisted rings, folded rings with a short branch, and stacked rings. Many of the larger structures are stabilized by weak C-H···O bonds.

High power, high beam quality regenerative amplifier

DOEpatents

Hackel, L.A.; Dane, C.B.

1993-08-24

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

High power, high beam quality regenerative amplifier

DOEpatents

Hackel, Lloyd A.; Dane, Clifford B.

1993-01-01

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

Optical control of spin-dependent thermal transport in a quantum ring

NASA Astrophysics Data System (ADS)

Abdullah, Nzar Rauf

2018-05-01

We report on calculation of spin-dependent thermal transport through a quantum ring with the Rashba spin-orbit interaction. The quantum ring is connected to two electron reservoirs with different temperatures. Tuning the Rashba coupling constant, degenerate energy states are formed leading to a suppression of the heat and thermoelectric currents. In addition, the quantum ring is coupled to a photon cavity with a single photon mode and linearly polarized photon field. In a resonance regime, when the photon energy is approximately equal to the energy spacing between two lowest degenerate states of the ring, the polarized photon field can significantly control the heat and thermoelectric currents in the system. The roles of the number of photon initially in the cavity, and electron-photon coupling strength on spin-dependent heat and thermoelectric currents are presented.

Modeling of anisotropic properties of double quantum rings by the terahertz laser field.

PubMed

Baghramyan, Henrikh M; Barseghyan, Manuk G; Kirakosyan, Albert A; Ojeda, Judith H; Bragard, Jean; Laroze, David

2018-04-18

The rendering of different shapes of just a single sample of a concentric double quantum ring is demonstrated realizable with a terahertz laser field, that in turn, allows the manipulation of electronic and optical properties of a sample. It is shown that by changing the intensity or frequency of laser field, one can come to a new set of degenerated levels in double quantum rings and switch the charge distribution between the rings. In addition, depending on the direction of an additional static electric field, the linear and quadratic quantum confined Stark effects are observed. The absorption spectrum shifts and the additive absorption coefficient variations affected by laser and electric fields are discussed. Finally, anisotropic electronic and optical properties of isotropic concentric double quantum rings are modeled with the help of terahertz laser field.

A new paradigm for designing ring construction strategies for green organic synthesis: implications for the discovery of multicomponent reactions to build molecules containing a single ring

PubMed Central

2016-01-01

A new way of developing novel synthesis strategies for the construction of monocyclic rings found in organic molecules is presented. The method is based on the visual application of integer partitioning to chemical structures. Two problems are addressed: (1) the determination of the total number of possible ways to construct a given ring by 2-, 3-, and 4-component couplings; and (2) the systematic enumeration of those possibilities. The results of the method are illustrated using cyclohexanone, pyrazole, and the Biginelli adduct as target ring systems with a view to discover new and greener strategies for their construction using multicomponent reactions. The application of the method is also extended to various heterocycles found in many natural products and pharmaceuticals. PMID:28144310

MinCD cell division proteins form alternating co-polymeric cytomotive filaments

PubMed Central

Ghosal, Debnath; Trambaiolo, Daniel; Amos, Linda A.; Löwe, Jan

2014-01-01

Summary During bacterial cell division, filaments of the tubulin-like protein FtsZ assemble at midcell to form the cytokinetic Z-ring. Its positioning is regulated by the oscillation of MinCDE proteins. MinC is activated by MinD through an unknown mechanism and prevents Z-ring assembly anywhere but midcell. Here, using X-ray crystallography, electron microscopy and in vivo analyses we show that MinD activates MinC by forming a new class of alternating copolymeric filaments that show similarity to eukaryotic septin filaments A non-polymerising mutation in MinD causes aberrant cell division in E. coli. MinCD copolymers bind to membrane, interact with FtsZ, and are disassembled by MinE. Imaging a functional msfGFP-MinC fusion protein in MinE deleted cells reveals filamentous structures. EM imaging of our reconstitution of the MinCD-FtsZ interaction on liposome surfaces reveals a plausible mechanism for regulation of FtsZ ring assembly by MinCD copolymers. PMID:25500731

Assembly and positioning of actomyosin rings by contractility and planar cell polarity

PubMed Central

Sehring, Ivonne M; Recho, Pierre; Denker, Elsa; Kourakis, Matthew; Mathiesen, Birthe; Hannezo, Edouard; Dong, Bo; Jiang, Di

2015-01-01

The actomyosin cytoskeleton is a primary force-generating mechanism in morphogenesis, thus a robust spatial control of cytoskeletal positioning is essential. In this report, we demonstrate that actomyosin contractility and planar cell polarity (PCP) interact in post-mitotic Ciona notochord cells to self-assemble and reposition actomyosin rings, which play an essential role for cell elongation. Intriguingly, rings always form at the cells′ anterior edge before migrating towards the center as contractility increases, reflecting a novel dynamical property of the cortex. Our drug and genetic manipulations uncover a tug-of-war between contractility, which localizes cortical flows toward the equator and PCP, which tries to reposition them. We develop a simple model of the physical forces underlying this tug-of-war, which quantitatively reproduces our results. We thus propose a quantitative framework for dissecting the relative contribution of contractility and PCP to the self-assembly and repositioning of cytoskeletal structures, which should be applicable to other morphogenetic events. DOI: http://dx.doi.org/10.7554/eLife.09206.001 PMID:26486861

Development of silicon photonic microring resonator biosensors for multiplexed cytokine assays and in vitro diagnostics

NASA Astrophysics Data System (ADS)

Luchansky, Matthew Sam

In order to guide critical care therapies that are personalized to a patient's unique disease state, a diagnostic or theranostic medical device must quickly provide a detailed biomolecular understanding of disease onset and progression. This detailed molecular understanding of cellular processes and pathways requires the ability to measure multiple analytes in parallel. Though many traditional sensing technologies for biomarker analysis and fundamental biological studies (i.e. enzyme-linked immunosorbent assays, real-time polymerase chain reaction, etc.) rely on single-parameter measurements, it has become increasingly clear that the inherent complexity of many human illnesses and pathways necessitates quantitative and multiparameter analysis of biological samples. Currently used analytical methods are deficient in that they often provide either highly quantitative data for a single biomarker or qualitative data for many targets, but methods that simultaneously provide highly quantitative analysis of many targets have yet to be adequately developed. Fields such as medical diagnostics and cellular biology would benefit greatly from a technology that enables rapid, quantitative and reproducible assays for many targets within a single sample. In an effort to fill this unmet need, this doctoral dissertation describes the development of a clinically translational biosensing technology based on silicon photonics and developed in the chemistry research laboratory of Ryan C. Bailey. Silicon photonic microring resonators, a class of high-Q optical sensors, represent a promising platform for rapid, multiparameter in vitro measurements. The original device design utilizes 32-ring arrays for real-time biomolecular sensing without fluorescent labels, and these optical biosensors display great potential for more highly multiplexed (100s-1000s) measurements based on the impressive scalability of silicon device fabrication. Though this technology can be used to detect a variety of molecules, this dissertation establishes the utility of microring resonator chips for multiparameter analysis of several challenging protein targets in cell cultures, human blood sera, and other clinical samples such as cerebrospinal fluid. Various sandwich immunoassay formats for diverse protein analytes are described herein, but the bulk of this dissertation focuses on applying the technology to cytokine analysis. Cytokines are small signaling proteins that are present in serum and cell secretomes at concentrations in the pg/mL or ng/mL range. Cytokines are very challenging to quantitate due to their low abundance and small size, but play important roles in a variety of immune response and inflammatory pathways; cytokine quantitation is thus important in fundamental biological studies and diagnostics, and complex and overlapping cytokine roles make multiplexed measurements especially vital. In a typical experiment, microfluidics are used to spatially control chip functionalization by directing capture antibodies against a variety of protein targets to groups of microring sensors. In each case, binding of analytes to the rings causes a change in the local refractive index that is transduced into a real-time, quantitative optical signal. This photonic sensing modality is based on the interaction of the propagating evanescent field with molecules near the ring surface. Since each microring sensor in the array is monitored independently, this technology allows multiple proteins to be quantified in parallel from a single sample. This dissertation describes the fabrication, characterization, development, and application of silicon photonic microring resonator technology to multiplexed protein measurements in a variety of biological systems. Chapter 1 introduces the field of high-Q optical sensors and places microring resonator technology within the broader context of related whispering gallery mode devices. The final stages of cleanroom device fabrication, in which 8" silicon wafers that contain hundreds of ring resonator arrays are transformed into individual functional chips, are described in Chapter 2. Chapter 3 characterizes the physical and optical properties of the microring resonator arrays, especially focusing on the evanescent field profile and mass sensitivity metrics. Chapter 4 demonstrates the ability to apply ring resonator technology to cytokine detection and T cell secretion analysis. Chapter 5 builds on the initial cytokine work to demonstrate the simultaneous detection of multiple cytokines with higher throughput to enable studies of T cell differentiation. In preparation for reaching the goal of cytokine analysis in clinical samples, Chapter 6 describes magnetic bead-based signal enhancement of sandwich immunoassays for serum analysis. Additional examples of the utility of nanoparticles and sub-micron beads for signal amplification are described in Chapter 7, also demonstrating the ability to monitor single bead binding events. Chapter 8 describes an alternative cytokine signal enhancement strategy based on enzymatic amplification for human cerebrospinal fluid (CSF) analysis. Chapter 9 adds work with other CSF protein targets that are relevant to the continuing development of a multiparameter Alzheimer's Disease diagnostic chip. Future directions for multiplexed protein analysis as it pertains to important immunological studies and in vitro diagnostic applications are defined in Chapter 10. (Abstract shortened by UMI.).

High Ringxiety: Attachment Anxiety Predicts Experiences of Phantom Cell Phone Ringing.

PubMed

Kruger, Daniel J; Djerf, Jaikob M

2016-01-01

Mobile cell phone users have reported experiencing ringing and/or vibrations associated with incoming calls and messages, only to find that no call or message had actually registered. We believe this phenomenon can be understood as a human signal detection issue, with potentially important influences from psychological attributes. We hypothesized that individuals higher in attachment anxiety would report more frequent phantom cell phone experiences, whereas individuals higher in attachment avoidance would report less frequent experiences. If these experiences are primarily psychologically related to attributes of interpersonal relationships, associations with attachment style should be stronger than for general sensation seeking. We also predicted that certain contexts would interact with attachment style to increase or decrease the likelihood of experiencing phantom cell phone calls and messages. Attachment anxiety directly predicted the frequency of phantom ringing and notification experiences, whereas attachment avoidance and sensation seeking did not directly predict frequency. Attachment anxiety and attachment avoidance interacted with contextual factors (expectations for a call or message and concerned about an issue that one may be contacted about) in the expected directions for predicting phantom cell phone experiences.

A randomised trial of a contraceptive vaginal ring in women at risk of HIV infection in Rwanda: Safety of intermittent and continuous use

PubMed Central

Van Nuil, Jennifer Ilo; Uwineza, Mireille; Umulisa, Marie Michelle; Mwambarangwe, Lambert; Ndagijimana, Jean Claude; De Baetselier, Irith; Buyze, Jozefien; Delvaux, Thérèse; Crucitti, Tania; Jespers, Vicky

2018-01-01

Background Contraceptive vaginal rings could play a role in expanding the contraceptive method mix and in preparing communities for the introduction of HIV prevention and multipurpose rings. Methods We conducted an open label single-centre randomised clinical trial of intermittent versus continuous use of NuvaRing® in Kigali, Rwanda, in 2013–2014. We randomised 120 HIV-negative women 1:1 to intermittent use (three rings with a ring-free week in between rings) or continuous use (four rings without ring-free weeks). Women underwent an interview, counselling, and a speculum examination, and were tested for pregnancy, bacterial vaginosis (BV) by Nugent scoring, yeasts and trichomonads on wet mount, and sexually transmitted infections. Findings Only one woman withdrew early. Deliberate ring removals were rare, but spontaneous ring expulsions occurred during 14% of ring use periods. There were no incident pregnancies, serious adverse events, serious social harms, or early discontinuations for safety reasons. Systemic side effects were uncommon, and local side effects were not significantly differently distributed between groups except for lower abdominal pain (P = 0.013). The incidence of vaginal yeasts during ring use was high: 22% of intermittent users and 27% of continuous users had incident vaginal yeasts at one or multiple ring removal visits (P = 0.666), and symptomatic vaginal yeast cases were more common in the continuous than intermittent users (P = 0.031). In contrast, mean Nugent scores improved over time in both groups. Conclusions Intermittent and continuous NuvaRing® use were safe in Rwandan women and improved Nugent scores over time. However, attention should be paid to ring expulsions and to a potential increased risk of vaginal candidiasis. PMID:29856848

Quantitative analysis of mechanical force required for cell extrusion in zebrafish embryonic epithelia.

PubMed

Yamada, Sohei; Iino, Takanori; Bessho, Yasumasa; Hosokawa, Yoichiroh; Matsui, Takaaki

2017-10-15

When cells in epithelial sheets are damaged by intrinsic or extrinsic causes, they are eliminated by extrusion from the sheet. Cell extrusion, which is required for maintenance of tissue integrity, is the consequence of contraction of actomyosin rings, as demonstrated by both molecular/cellular biological experimentation and numerical simulation. However, quantitative evaluation of actomyosin contraction has not been performed because of the lack of a suitable direct measurement system. In this study, we developed a new method using a femtosecond laser to quantify the contraction force of the actomyosin ring during cell extrusion in zebrafish embryonic epithelia. In this system, an epithelial cell in zebrafish embryo is first damaged by direct femtosecond laser irradiation. Next, a femtosecond laser-induced impulsive force is loaded onto the actomyosin ring, and the contraction force is quantified to be on the order of kPa as a unit of pressure. We found that cell extrusion was delayed when the contraction force was slightly attenuated, suggesting that a relatively small force is sufficient to drive cell extrusion. Thus, our method is suitable for the relative quantitative evaluation of mechanical dynamics in the process of cell extrusion, and in principle the method is applicable to similar phenomena in different tissues and organs of various species. © 2017. Published by The Company of Biologists Ltd.

Fuel cell stack with internal manifolds for reactant gases

DOEpatents

Schnacke, Arthur W.

1985-01-01

A fuel cell stack includes a plurality of plate-like fuel cells arranged along an axis generally parallel to cell thickness with electrically conductive separator plates between each pair of cells. A plurality of axial manifolds are provided at opposite sides of the stack in outer marginal portions beyond the edges of electrodes and electrolyte tiles. Sealing rings prevent cross-leakage of oxidant fuel gases through use of pairs of outwardly extending lips from opposite tile surfaces bonded to first and second electrode frames respectively. The frames provide transition between electrode edges and manifold perimeters. The pairs of extension lips are sealingly bonded together through an electrically insulative sealing ring with wedge shaped fastening members.

Fuel cell stack with internal manifolds for reactant gases

DOEpatents

Schnacke, A.W.

1983-10-12

A fuel cell stack includes a plurality of plate-like fuel cells arranged along an axis generally parallel to cell thickness with electrically conductive separator plates between each pair of cells. A plurality of axial manifolds are provided at opposite sides of the stack in outer marginal portions beyond the edges of electrodes and electrolyte tiles. Sealing rings prevent cross-leakage of oxidant fuel gases through use of pairs of outwardly extending lips from opposite tile surfaces bonded to first and second electrode frames respectively. The frames provide transition between electrode edges and manifold perimeters. The pairs of extension lips are sealingly bonded together through an electrically insulative sealing ring with wedge shaped fastening members.

How does climate influence xylem morphogenesis over the growing season? Insights from long-term intra-ring anatomy in Picea abies

PubMed Central

Fonti, Patrick; von Arx, Georg; Carrer, Marco

2017-01-01

Background and Aims During the growing season, the cambium of conifer trees produces successive rows of xylem cells, the tracheids, that sequentially pass through the phases of enlargement and secondary wall thickening before dying and becoming functional. Climate variability can strongly influence the kinetics of morphogenetic processes, eventually affecting tracheid shape and size. This study investigates xylem anatomical structure in the stem of Picea abies to retrospectively infer how, in the long term, climate affects the processes of cell enlargement and wall thickening. Methods Tracheid anatomical traits related to the phases of enlargement (diameter) and wall thickening (wall thickness) were innovatively inspected at the intra-ring level on 87-year-long tree-ring series in Picea abies trees along a 900 m elevation gradient in the Italian Alps. Anatomical traits in ten successive tree-ring sectors were related to daily temperature and precipitation data using running correlations. Key Results Close to the altitudinal tree limit, low early-summer temperature negatively affected cell enlargement. At lower elevation, water availability in early summer was positively related to cell diameter. The timing of these relationships shifted forward by about 20 (high elevation) to 40 (low elevation) d from the first to the last tracheids in the ring. Cell wall thickening was affected by climate in a different period in the season. In particular, wall thickness of late-formed tracheids was strongly positively related to August–September temperature at high elevation. Conclusions Morphogenesis of tracheids sequentially formed in the growing season is influenced by climate conditions in successive periods. The distinct climate impacts on cell enlargement and wall thickening indicate that different morphogenetic mechanisms are responsible for different tracheid traits. Our approach of long-term and high-resolution analysis of xylem anatomy can support and extend short-term xylogenesis observations, and increase our understanding of climate control of tree growth and functioning under different environmental conditions. PMID:28130220

The role of microtubules in contractile ring function.

PubMed

Conrad, A H; Paulsen, A Q; Conrad, G W

1992-05-01

During cytokinesis, a cortical contractile ring forms around a cell, constricts to a stable tight neck and terminates in separation of the daughter cells. At first cleavage, Ilyanassa obsoleta embryos form two contractile rings simultaneously. The cleavage furrow (CF), in the animal hemisphere between the spindle poles, constricts to a stable tight neck and separates the daughter cells. The third polar lobe constriction (PLC-3), in the vegetal hemisphere below the spindle, constricts to a transient tight neck, but then relaxes, allowing the polar lobe cytoplasm to merge with one daughter cell. Eggs exposed to taxol, a drug that stabilizes microtubules, before the CF or the PLC-3 develop, fail to form CFs, but form stabilized tight PLCs. Eggs exposed to taxol at the time of PLC-3 formation develop varied numbers of constriction rings in their animal hemispheres and one PLC in their vegetal hemisphere, none of which relax. Eggs exposed to taxol after PLC-3 initiation form stabilized tight CFs and PLCs. At maximum constriction, control embryos display immunolocalization of nonextractable alpha-tubulin in their CFs, but not in their PLCs, and reveal, via electron microscopy, many microtubules extending through their CFs, but not through their PLCs. Embryos which form stabilized tightly constricted CFs and PLCs in the presence of taxol display immunolocalization of nonextractable alpha-tubulin in both constrictions and show many polymerized microtubules extending through both CFs and PLCs. These results suggest that the extension of microtubules through a tight contractile ring may be important for stabilizing that constriction and facilitating subsequent cytokinesis.

The role of microtubules in contractile ring function

NASA Technical Reports Server (NTRS)

Conrad, A. H.; Paulsen, A. Q.; Conrad, G. W.; Spooner, B. S. (Principal Investigator)

1992-01-01

During cytokinesis, a cortical contractile ring forms around a cell, constricts to a stable tight neck and terminates in separation of the daughter cells. At first cleavage, Ilyanassa obsoleta embryos form two contractile rings simultaneously. The cleavage furrow (CF), in the animal hemisphere between the spindle poles, constricts to a stable tight neck and separates the daughter cells. The third polar lobe constriction (PLC-3), in the vegetal hemisphere below the spindle, constricts to a transient tight neck, but then relaxes, allowing the polar lobe cytoplasm to merge with one daughter cell. Eggs exposed to taxol, a drug that stabilizes microtubules, before the CF or the PLC-3 develop, fail to form CFs, but form stabilized tight PLCs. Eggs exposed to taxol at the time of PLC-3 formation develop varied numbers of constriction rings in their animal hemispheres and one PLC in their vegetal hemisphere, none of which relax. Eggs exposed to taxol after PLC-3 initiation form stabilized tight CFs and PLCs. At maximum constriction, control embryos display immunolocalization of nonextractable alpha-tubulin in their CFs, but not in their PLCs, and reveal, via electron microscopy, many microtubules extending through their CFs, but not through their PLCs. Embryos which form stabilized tightly constricted CFs and PLCs in the presence of taxol display immunolocalization of nonextractable alpha-tubulin in both constrictions and show many polymerized microtubules extending through both CFs and PLCs. These results suggest that the extension of microtubules through a tight contractile ring may be important for stabilizing that constriction and facilitating subsequent cytokinesis.

Process model simulations of the divergence effect

NASA Astrophysics Data System (ADS)

Anchukaitis, K. J.; Evans, M. N.; D'Arrigo, R. D.; Smerdon, J. E.; Hughes, M. K.; Kaplan, A.; Vaganov, E. A.

2007-12-01

We explore the extent to which the Vaganov-Shashkin (VS) model of conifer tree-ring formation can explain evidence for changing relationships between climate and tree growth over recent decades. The VS model is driven by daily environmental forcing (temperature, soil moisture, and solar radiation), and simulates tree-ring growth cell-by-cell as a function of the most limiting environmental control. This simplified representation of tree physiology allows us to examine using a selection of case studies whether instances of divergence may be explained in terms of changes in limiting environmental dependencies or transient climate change. Identification of model-data differences permits further exploration of the effects of tree-ring standardization, atmospheric composition, and additional non-climatic factors.

Switchable and tunable dual-wavelength Er-doped fiber ring laser with single-frequency lasing wavelengths

NASA Astrophysics Data System (ADS)

Zhang, Haiwei; Shi, Wei; Bai, Xiaolei; Sheng, Quan; Xue, Lifang; Yao, Jianquan

2018-02-01

We obtain a switchable and tunable dual-wavelength single-frequency Er-doped ring fiber laser. In order to realize single-longitudinal output, two saturable-absorber-based tracking narrow-band filters are formed in 3- meter-long unpumped Er-doped fiber to narrow the linewidth via using the PM-FBG as a reflection filter. The maximum output power is 2.11 mW centered at 1550.16 nm and 1550.54 nm when the fiber laser operates in dual-wavelength mode. The corresponding linewidths of those two wavelengths are measured to be 769 Hz and 673 Hz, respectively. When the temperature around the PM-FBG is changed from 15 °C to 55 °C, the dual-wavelength single-frequency fiber laser can be tuned from 1550.12 nm to 1550.52 nm and from 1550.49 nm to 1550.82 nm, respectively.

To the nucleolar bodies (nucleoli) in cells of the lymphocytic lineage in patients suffering from B - chronic lymphocytic leukemia.

PubMed

Smetana, K; Karban, J; Trneny, M

2010-01-01

The present study was undertaken to provide more information on nucleoli in lymphocytes of B - chronic lymphocytic leukemia. The computer assisted nucleolar and cytoplasmic RNA image densitometry, reflecting the nucleolar and cytoplasmic RNA concentration at the single cell level, demonstrated a remarkable stability during the differentiation and maturation of B- lymphocytes. In contrast, as it was expected, the nucleolar diameter during the lymphocytic development markedly decreased. Thus the nucleolar RNA content of leukemic B-lymphocytes was apparently related to the nucleolar size. In both immature and mature lymphocytes, the cytostatic treatment increased the incidence of micronucleoli, which represent the "inactive" type of nucleoli. However, the decreased values of the nucleolar diameter were statistically significant only in mature lymphocytes of treated patients. On the other hand, despite such observation, it must be mentioned that "large active" and "ring shaped resting" nucleoli were still present in immature and mature lymphocytes after the cytostatic therapy and such cells might represent a potential pool of proliferating cells. As it is generally accepted "large active nucleoli" with multiple fibrillar centers are known to be characteristic for proliferating cells. "Ring shaped resting nucleoli" are present in sleeping cells, which may be stimulated to return to the cell cycle and to proliferate again. In addition, the nucleolar RNA distribution also indicated that Gumprecht ghosts mostly originated from mature lymphocytes. Increased ratio of the nucleolar to cytoplasmic RNA density in Gumprecht ghosts or apoptotic cells and apoptotic bodies of the lymphocytic origin was related to the decreased cytoplasmic RNA concentration. The increased nucleolar size together with the markedly decreased cytoplasmic RNA concentration characteristic for Gumprecht ghosts just reflected the spreading of lymphocytes during smear preparations. In apoptotic cells or bodies of the lymphocytic origin, the "frozen" nucleolar RNA concentration accompanied by a reduced RNA concentration in the cytoplasm exhibited a remarkable similarity to the apoptotic process induced in vitro by the cytostatic treatment. B-chronic lymphocytic leukemia; lymphocytes; nucleolar classes; size; nucleolar RNA image density -concentration.

High-molecular-weight tropomyosins localize to the contractile rings of dividing CNS cells but are absent from malignant pediatric and adult CNS tumors.

PubMed

Hughes, Julie A I; Cooke-Yarborough, Claire M; Chadwick, Nigel C; Schevzov, Galina; Arbuckle, Susan M; Gunning, Peter; Weinberger, Ron P

2003-04-01

Tropomyosin has been implicated in the control of actin filament dynamics during cell migration, morphogenesis, and cytokinesis. In order to gain insight into the role of tropomyosins in cell division, we examined their expression in developing and neoplastic brain tissue. We found that the high-molecular-weight tropomyosins are downregulated at birth, which correlates with glial cell differentiation and withdrawal of most cells from the cell cycle. Expression of these isoforms was restricted to proliferative areas in the embryonic brain and was absent from the adult, where the majority of cells are quiescent. However, they were induced under conditions where glial cells became proliferative in response to injury. During cytokinesis, these tropomyosin isoforms were associated with the contractile ring. We also investigated tropomyosin expression in neoplastic CNS tissues. Low-grade astrocytic tumors expressed high-molecular-weight tropomyosins, while highly malignant CNS tumors of diverse origin did not (P

Stochastic simulation tools and continuum models for describing two-dimensional collective cell spreading with universal growth functions

NASA Astrophysics Data System (ADS)

Jin, Wang; Penington, Catherine J.; McCue, Scott W.; Simpson, Matthew J.

2016-10-01

Two-dimensional collective cell migration assays are used to study cancer and tissue repair. These assays involve combined cell migration and cell proliferation processes, both of which are modulated by cell-to-cell crowding. Previous discrete models of collective cell migration assays involve a nearest-neighbour proliferation mechanism where crowding effects are incorporated by aborting potential proliferation events if the randomly chosen target site is occupied. There are two limitations of this traditional approach: (i) it seems unreasonable to abort a potential proliferation event based on the occupancy of a single, randomly chosen target site; and, (ii) the continuum limit description of this mechanism leads to the standard logistic growth function, but some experimental evidence suggests that cells do not always proliferate logistically. Motivated by these observations, we introduce a generalised proliferation mechanism which allows non-nearest neighbour proliferation events to take place over a template of r≥slant 1 concentric rings of lattice sites. Further, the decision to abort potential proliferation events is made using a crowding function, f(C), which accounts for the density of agents within a group of sites rather than dealing with the occupancy of a single randomly chosen site. Analysing the continuum limit description of the stochastic model shows that the standard logistic source term, λ C(1-C), where λ is the proliferation rate, is generalised to a universal growth function, λ C f(C). Comparing the solution of the continuum description with averaged simulation data indicates that the continuum model performs well for many choices of f(C) and r. For nonlinear f(C), the quality of the continuum-discrete match increases with r.

Stochastic simulation tools and continuum models for describing two-dimensional collective cell spreading with universal growth functions.

PubMed

Jin, Wang; Penington, Catherine J; McCue, Scott W; Simpson, Matthew J

2016-10-07

Two-dimensional collective cell migration assays are used to study cancer and tissue repair. These assays involve combined cell migration and cell proliferation processes, both of which are modulated by cell-to-cell crowding. Previous discrete models of collective cell migration assays involve a nearest-neighbour proliferation mechanism where crowding effects are incorporated by aborting potential proliferation events if the randomly chosen target site is occupied. There are two limitations of this traditional approach: (i) it seems unreasonable to abort a potential proliferation event based on the occupancy of a single, randomly chosen target site; and, (ii) the continuum limit description of this mechanism leads to the standard logistic growth function, but some experimental evidence suggests that cells do not always proliferate logistically. Motivated by these observations, we introduce a generalised proliferation mechanism which allows non-nearest neighbour proliferation events to take place over a template of [Formula: see text] concentric rings of lattice sites. Further, the decision to abort potential proliferation events is made using a crowding function, f(C), which accounts for the density of agents within a group of sites rather than dealing with the occupancy of a single randomly chosen site. Analysing the continuum limit description of the stochastic model shows that the standard logistic source term, [Formula: see text], where λ is the proliferation rate, is generalised to a universal growth function, [Formula: see text]. Comparing the solution of the continuum description with averaged simulation data indicates that the continuum model performs well for many choices of f(C) and r. For nonlinear f(C), the quality of the continuum-discrete match increases with r.

Design, synthesis and biological evaluation of arylcinnamide hybrid derivatives as novel anticancer agents

PubMed Central

Romagnoli, Romeo; Baraldi, Pier Giovanni; Salvador, Maria Kimatrai; Chayah, Mariem; Camacho, M. Encarnacion; Prencipe, Filippo; Hamel, Ernest; Consolaro, Francesca; Basso, Giuseppe; Viola, Giampietro

2014-01-01

The combination of two pharmacophores into a single molecule represents one of the methods that can be adopted for the synthesis of new anticancer molecules. A series of novel antiproliferative agents designed by a pharmacophore hybridization approach, combining the arylcinnamide skeleton and an α-bromoacryloyl moiety, was synthesized and evaluated for its antiproliferative activity against a panel of seven human cancer cell lines. In addition, the new derivatives were also active on multidrug-resistant cell lines over-expressing P-glycoprotein. The biological effects of various substituents on the N-phenyl ring of the benzamide portion were also described. In order to study the possible mechanism of action, we observed that 4p slightly increased the Reactive Oxygen Species (ROS) production in HeLa cells, but, more importantly, a remarkable decrease of intracellular reduced glutathione content was detected in treated cells compared with controls. These results were confirmed by the observation that only thiol-containing antioxidants were able to significantly protect the cells from induced cell death. Altogether our results indicate that the new derivatives are endowed with good anticancer activity in vitro, and their properties may result in the development of new cancer therapeutic strategies. PMID:24858544

XRD, vibrational spectra and quantum chemical studies of an anticancer drug: 6-Mercaptopurine.

PubMed

Kumar, S Suresh; Athimoolam, S; Sridhar, B

2015-07-05

The single crystal of the hydrated anticancer drug, 6-Mercaptopurine (6-MP), has been grown by slow evaporation technique under room temperature. The structure was determined by single crystal X-ray diffraction. The vibrational spectral analysis was carried out using Laser Raman and FT-IR spectroscopy in the range of 3300-100 and 4000-400 cm(-1). The single crystal X-ray studies shows that the crystal packing is dominated by N-H⋯O and O-H⋯N classical hydrogen bonds leading to a hydrogen bonded ensemble. This classical hydrogen bonds were further connected through O-H⋯S hydrogen bond to form two primary ring R4(4)(16) and R4(4)(12) motifs. These two primary ring motifs are interlinked with each other to build a ladder like structure. These ladders are connected through N-H⋯N hydrogen bond along c-axis of the unit cell through chain C(5) motifs. Further, the strength of the hydrogen bonds is studied through vibrational spectral measurements. The shifting of bands due to the intermolecular interactions was also analyzed in the solid crystalline state. Geometrical optimizations of the drug molecule were done by Density Functional Theory (DFT) using the B3LYP function and Hartree-Fock (HF) level with 6-311++G(d,p) basis set. The optimized molecular geometry and computed vibrational spectra are compared with experimental results which show significant agreement. The natural bond orbital (NBO) analysis was carried out to interpret hyperconjugative interaction and intramolecular charge transfer (ICT). The chemical hardness, electro-negativity and chemical potential of the molecule are carried out by HOMO-LUMO plot. In which, the frontier orbitals has lower band gap value indicating the possible pharmaceutical activity of the molecule. Copyright © 2015 Elsevier B.V. All rights reserved.

Transfer matrix approach to the persistent current in quantum rings: Application to hybrid normal-superconducting rings

NASA Astrophysics Data System (ADS)

Nava, Andrea; Giuliano, Rosa; Campagnano, Gabriele; Giuliano, Domenico

2016-11-01

Using the properties of the transfer matrix of one-dimensional quantum mechanical systems, we derive an exact formula for the persistent current across a quantum mechanical ring pierced by a magnetic flux Φ as a single integral of a known function of the system's parameters. Our approach provides exact results at zero temperature, which can be readily extended to a finite temperature T . We apply our technique to exactly compute the persistent current through p -wave and s -wave superconducting-normal hybrid rings, deriving full plots of the current as a function of the applied flux at various system's scales. Doing so, we recover at once a number of effects such as the crossover in the current periodicity on increasing the size of the ring and the signature of the topological phase transition in the p -wave case. In the limit of a large ring size, resorting to a systematic expansion in inverse powers of the ring length, we derive exact analytic closed-form formulas, applicable to a number of cases of physical interest.

Hawaii Energy and Environmental Technologies Initiative 2010 (HEET10)

DTIC Science & Technology

2016-09-30

illustrated how local battery storage support of the lOMW Hawi wind farm can cause grid-wide issues. However, it was found that battery cycling can...capabilities pertaining to three different ex situ diagnostics were acquired and used under HEETlO. Focus was given to the catalyst (rotating ring ...cell. These capabilities are illustrated in Figure 9 1.1.1. Figure 1.1.1: (left) rotating ring /disc electrode; (middle) membrane conductivity cell

Destructive Single-Event Failures in Diodes

NASA Technical Reports Server (NTRS)

Casey, Megan C.; Gigliuto, Robert A.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Kim, Hak; Chen, Dakai; Phan, Anthony M.; LaBel, Kenneth A.

2013-01-01

In this summary, we have shown that diodes are susceptible to destructive single-event effects, and that these failures occur along the guard ring. By determining the last passing voltages, a safe operating area can be derived. By derating off of those values, rather than by the rated voltage, like what is currently done with power MOSFETs, we can work to ensure the safety of future missions. However, there are still open questions about these failures. Are they limited to a single manufacturer, a small number, or all of them? Is there a threshold rated voltage that must be exceeded to see these failures? With future work, we hope to answer these questions. In the full paper, laser results will also be presented to verify that failures only occur along the guard ring.

Visible near-infrared light scattering of single silver split-ring structure made by nanosphere lithography.

PubMed

Okamoto, Toshihiro; Fukuta, Tetsuya; Sato, Shuji; Haraguchi, Masanobu; Fukui, Masuo

2011-04-11

We succeeded in making a silver split-ring (SR) structure of approximately 130 nm in diameter on a glass substrate using a nanosphere lithography technique. The light scattering spectrum in visible near-infrared region of a single, isolated SR was measured using a microscope spectroscopy optical system. The electromagnetic field enhancement spectrum and distribution of the SR structure were simulated by the finite-difference time-domain method, and the excitation modes were clarified. The long wavelength peak in the light scattering spectra corresponded to a fundamental LC resonance mode excited by an incident electric field. It was shown that a single SR structure fabricated as abovementioned can operate as a resonator and generate a magnetic dipole. © 2011 Optical Society of America

Two semiconductor ring lasers coupled by a single-waveguide for optical memory operation

NASA Astrophysics Data System (ADS)

Van der Sande, Guy; Coomans, Werner; Gelens, Lendert

2014-05-01

Semiconductor ring lasers are semiconductor lasers where the laser cavity consists of a ring-shaped waveguide. SRLs are highly integrable and scalable, making them ideal candidates for key components in photonic integrated circuits. SRLs can generate light in two counterpropagating directions between which bistability has been demonstrated. Hence, information can be coded into the emission direction. This bistable operation allows SRLs to be used in systems for all-optical switching and as all-optical memories. For the demonstration of fast optical flip-flop operation, Hill et al. [Nature 432, 206 (2004)] fabricated two SRLs coupled by a single waveguide, rather than a solitary SRL. Nevertheless, the literature shows that a single SRL can also function perfectly as an all-optical memory. In our recent paper [W. Coomans et al., Phys. Rev. A 88, 033813, (2013)], we have raised the question whether coupling two SRLs to realize a single optical memory has any advantage over using a solitary SRL, taking into account the obvious disadvantage of a doubled footprint and power consumption. To provide the answer, we have presented in that paper a numerical study of the dynamical behavior of semiconductor ring lasers coupled by a single bus waveguide, both when weakly coupled and when strongly coupled. We have provided a detailed analysis of the multistable landscape in the coupled system, analyzed the stability of all solutions and related the internal dynamics in the individual lasers to the field effectively measured at the output of the waveguide. We have shown which coupling phases generally promote instabilities and therefore need to be avoided in the design. Regarding all-optical memory operation, we have demonstrated that there is no real advantage for bistable memory operation compared to using a solitary SRL. An increased power suppression ratio has been found to be mainly due to the destructive interference of the SRL fields at the low power port. Also, multistability between several modal configurations has been shown to remain unavoidable.

Ring-through-ring molecular shuttling in a saturated [3]rotaxane

NASA Astrophysics Data System (ADS)

Zhu, Kelong; Baggi, Giorgio; Loeb, Stephen J.

2018-06-01

Mechanically interlocked molecules such as rotaxanes and catenanes comprise two or more components whose motion relative to each other can be controlled. A [2]rotaxane molecular shuttle, for example, consists of an axle bearing two recognition sites and a single macrocyclic wheel that can undergo a to-and-fro motion along the axle—shuttling between the recognition sites. The ability of mechanically interlocked molecules to undergo this type of large-amplitude change is the core mechanism behind almost every interlocked molecular switch or machine, including sophisticated mechanical systems such as a molecular elevator and a peptide synthesizer. Here, as a way to expand the scope of dynamics possible at the molecular level, we have developed a molecular shuttling mechanism involving the exchange of rings between two recognition sites in a saturated [3]rotaxane (one with no empty recognition sites). This was accomplished by passing a smaller ring through a larger one, thus achieving ring-through-ring molecular shuttling.

Structure of the human DNA-repair protein RAD52 containing surface mutations.

PubMed

Saotome, Mika; Saito, Kengo; Onodera, Keiichi; Kurumizaka, Hitoshi; Kagawa, Wataru

2016-08-01

The Rad52 protein is a eukaryotic single-strand DNA-annealing protein that is involved in the homologous recombinational repair of DNA double-strand breaks. The isolated N-terminal half of the human RAD52 protein (RAD52(1-212)) forms an undecameric ring structure with a surface that is mostly positively charged. In the present study, it was found that RAD52(1-212) containing alanine mutations of the charged surface residues (Lys102, Lys133 and Glu202) is highly amenable to crystallization. The structure of the mutant RAD52(1-212) was solved at 2.4 Å resolution. The structure revealed an association between the symmetry-related RAD52(1-212) rings, in which a partially unfolded, C-terminal region of RAD52 extended into the DNA-binding groove of the neighbouring ring in the crystal. The alanine mutations probably reduced the surface entropy of the RAD52(1-212) ring and stabilized the ring-ring association observed in the crystal.

Ultrasonic Resonance Spectroscopy of Composite Rings for Flywheel Rotors

NASA Technical Reports Server (NTRS)

Harmon, Laura M.; Baaklini, George Y.

2001-01-01

Flywheel energy storage devices comprising multilayered composite rotor systems are being studied extensively for utilization in the International Space Station. These composite material systems were investigated with a recently developed ultrasonic resonance spectroscopy technique. The system employs a swept frequency approach and performs a fast Fourier transform on the frequency spectrum of the response signal. In addition. the system allows for equalization of the frequency spectrum, providing all frequencies with equal amounts of energy to excite higher order resonant harmonics. Interpretation of the second fast Fourier transform, along with equalization of the frequency spectrum, offers greater assurance in acquiring and analyzing the fundamental frequency, or spectrum resonance spacing. The range of frequencies swept in a pitch-catch mode was varied up to 8 MHz, depending on the material and geometry of the component. Single and multilayered material samples, with and without known defects, were evaluated to determine how the constituents of a composite material system affect the resonant frequency. Amplitude and frequency changes in the spectrum and spectrum resonance spacing domains were examined from ultrasonic responses of a flat composite coupon, thin composite rings, and thick composite rings. Also, the ultrasonic spectroscopy responses from areas with an intentional delamination and a foreign material insert, similar to defects that may occur during manufacturing malfunctions, were compared with those from defect-free areas in thin composite rings. A thick composite ring with varying thickness was tested to investigate the full-thickness resonant frequency and any possible bulk interfacial bond issues. Finally, the effect on the frequency response of naturally occurring single and clustered voids in a composite ring was established.

Mechanical deformation of carbon nanotube nano-rings on flat substrate

NASA Astrophysics Data System (ADS)

Zheng, Meng; Ke, Changhong

2011-04-01

We present a numerical analysis of the mechanical deformation of carbon nanotube (CNT) nano-rings on flat graphite substrates, which is motivated by our recent experimental findings on the elastic deformation of CNT nano-rings. Our analysis considers a perfectly circular CNT ring formed by bending a straight individual or bundled single-walled nanotube to connect its two ends. The seamless CNT ring is placed vertically on a flat graphite substrate and its respective deformation curvatures under zero external force, compressive, and tensile forces are determined using a continuum model based on nonlinear elastica theory. Our results show that the van der Waals interaction between the CNT ring and the substrate has profound effects on the deformation of the CNT ring, and that the interfacial binding interaction between the CNT ring and the substrate is strongly modulated by the ring deformation. Our results demonstrate that the CNT ring in force-free conditions has a flat ring segment in contact with the substrate if the ring radius R ≥√EI/2Wvdw , in which EI is the flexural rigidity of the nanotube and Wvdw is the per-unit-length van der Waals energy between the flat ring segment and the substrate. Our results reveal that the load-deformation profiles of the CNT ring under tensile loadings exhibit bifurcation behavior, which is ascribed to its van der Waals interaction with the substrate and is dependent on its relaxed conformation on the substrate. Our work suggests that CNT nano-rings are promising for a number of applications, such as ultrasensitive force sensors and stretchable and flexible structural components in nanoscale mechanical and electromechanical systems.

Single-staged vs. two-staged implant placement using bone ring technique in vertically deficient alveolar ridges - Part 1: histomorphometric and micro-CT analysis.

PubMed

Nakahara, Ken; Haga-Tsujimura, Maiko; Sawada, Kosaku; Kobayashi, Eizaburo; Mottini, Matthias; Schaller, Benoit; Saulacic, Nikola

2016-11-01

Simultaneous implant placement with bone grafting shortens the overall treatment period, but might lead to the peri-implant bone loss or even implant failure. The aim of this study was to compare the single-staged to two-staged implant placement using the bone ring technique. Four standardized alveolar bone defects were made in the mandibles of nine dogs. Dental implants (Straumann BL ® , Basel, Switzerland) were inserted simultaneously with bone ring technique in test group and after 6 months of healing period in control group. Animals of both groups were euthanized at 3 and 6 months of osseointegration period. The harvested samples were analyzed by means of histology and micro-CT. The amount of residual bone decreased while the amount of new bone increased up to 9 months of healing period. All morphometric parameters remained stable between 3 and 6 months of osseointegration period within groups. Per a given time point, median area of residual bone graft was higher in test group and area of new bone in control group. The volume of bone ring was greater in test than in control group, reaching the significance at 6 months of osseointegration period (P = 0.002). In the present type of bone defect, single-staged implant placement may be potentially useful to shorten an overall treatment period. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A new serial pooling method of shifted tree ring blocks to construct millennia long tree ring isotope chronologies with annual resolution.

PubMed

Boettger, Tatjana; Friedrich, Michael

2009-03-01

The study presents a new serial pooling method of shifted tree ring blocks for the building of isotope chronologies. This method combines the advantages of traditional 'serial' and 'intertree' pooling, and can be recommended for the construction of sub-regional long isotope chronologies with sufficient replication, and on annual resolution, especially for the case of extremely narrow tree rings. For Scots pines (Pinus sylvestris L., Khibiny Low Mountains, NW Russia) and Silver firs (Abies alba Mill., Franconia, Southern Germany), serial pooling of five consecutive tree rings seems appropriate because the species- and site-specific particularities lead to blurs of climate linkages in their tree rings for the period up to ca. five years back. An equivalent to a five-year running means that curve gained on the base annual data sets of single trees can be derived from the analysis of yearly shifted five-year blocks of consecutive tree rings, and therefore, with approximately 20% of the expense. Good coherence of delta(13)C- and delta(18)O-values between calculated means of annual total rings or late wood data and means of five-year blocks of consecutive total tree rings analysed experimentally on most similar material confirms this assumption.

The Shapers

NASA Image and Video Library

2015-01-26

Two masters of their craft are caught at work shaping Saturn's rings. Pandora (upper right) sculpts the F ring, as does nearby Prometheus (not seen in this image). Meanwhile, Daphnis is busy holding open the Keeler gap (bottom center), its presence revealed here by the waves it raises on the gap's edge. The faint moon is located where the inner and outer waves appear to meet. Also captured in this image, shining through the F ring above the image center, is a single star. Although gravity is by its very nature an attractive force, moons can interact with ring particles in such a way that they effectively push ring particles away from themselves. Ring particles experience tiny gravitational "kicks" from these moons and subsequently collide with other ring particles, losing orbital momentum. The net effect is for moons like Pandora (50 miles or 81 kilometers across) and Daphnis (5 miles or 8 kilometers across) to push ring edges away from themselves. The Keeler gap is the result of just such an interaction. This view looks toward the unilluminated side of the rings from about 50 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 30, 2013. http://photojournal.jpl.nasa.gov/catalog/PIA18298

Slide-Ring Materials Using Cyclodextrin.

PubMed

Ito, Kohzo

2017-01-01

We have recently synthesized slide-ring materials using cyclodextrin by cross-linking polyrotaxanes, a typical supramolecule. The slide-ring materials have polymer chains with bulky end groups topologically interlocked by figure-of-eight shaped junctions. This indicates that the cross-links can pass through the polymer chains similar to pulleys to relax the tension of the backbone polymer chains. The slide-ring materials also differ from conventional polymers in that the entropy of rings affects the elasticity. As a result, the slide-ring materials show quite small Young's modulus not proportional to the cross-linking density. This concept can be applied to a wide variety of polymeric materials as well as gels. In particular, the slide-ring materials show remarkable scratch-proof properties for coating materials for automobiles, cell phones, mobile computers, and so on. Further current applications include vibration-proof insulation materials for sound speakers, highly abrasive polishing media, dielectric actuators, and so on.

Waveguide-Coupled Superconducting Nanowire Single-Photon Detectors

NASA Technical Reports Server (NTRS)

Beyer, Andrew D.; Briggs, Ryan M.; Marsili, Francesco; Cohen, Justin D.; Meenehan, Sean M.; Painter, Oskar J.; Shaw, Matthew D.

2015-01-01

We have demonstrated WSi-based superconducting nanowire single-photon detectors coupled to SiNx waveguides with integrated ring resonators. This photonics platform enables the implementation of robust and efficient photon-counting detectors with fine spectral resolution near 1550 nm.

Testing the assumption of annual shell ring deposition in freshwater mussels

Treesearch

Wendell R. Haag; Amy M. Commens-Carson

2008-01-01

We tested the assumption of annual shell ring deposition by freshwater mussels in three rivers using 17 species. In 2000, we notched shell margins, returned animals to the water, and retrieved them in 2001. In 2003, we measured shells, affixed numbered tags, returned animals, and retrieved them in 2004 and 2005. We validated deposition of a single internal annulus per...

Erbium-doped fiber ring laser with SMS modal interferometer for hydrogen sensing

NASA Astrophysics Data System (ADS)

Zhang, Ya-nan; Zhang, Lebin; Han, Bo; Peng, Huijie; Zhou, Tianmin; Lv, Ri-qing

2018-06-01

A hydrogen sensor based on erbium-doped fiber ring laser with modal interferometer is proposed. A single mode-multimode-single mode (SMS) modal interferometer structure coated with Pd/WO3 film is used as the sensing head, due to that it is easy to be fabricated and low cost. The sensing structure is inserted into an erbium-doped fiber ring laser in order to solve the problem of spectral confusion and improve the detection limit of the hydrogen sensor based on the SMS modal interferometer. The SMS sensing structure is acted as a fiber band-pass filter. When hydrogen concentration around the sensor is changed, it will induce the refractive index and strain variations of the Pd/WO3 film, and then shift the resonant spectrum of the SMS modal interferometer as well as the laser wavelength of the fiber ring laser. Therefore, the hydrogen concentration can be measured by monitoring the wavelength shift of the laser, which has high intensity and narrow full width half maximum. Experimental results demonstrate that the sensor has high sensitivity of 1.23 nm/%, low detection limit of 0.017%, good stability and excellent repeatability.

Crystal structure of a two-subunit TrkA octameric gating ring assembly

DOE PAGES

Deller, Marc C.; Johnson, Hope A.; Miller, Mitchell D.; ...

2015-03-31

The TM1088 locus of T. maritima codes for two proteins designated TM1088A and TM1088B, which combine to form the cytosolic portion of a putative Trk K⁺ transporter. We report the crystal structure of this assembly to a resolution of 3.45 Å. The high resolution crystal structures of the components of the assembly, TM1088A and TM1088B, were also determined independently to 1.50 Å and 1.55 Å, respectively. The TM1088 proteins are structurally homologous to each other and to other K⁺ transporter proteins, such as TrkA. These proteins form a cytosolic gating ring assembly that controls the flow of K⁺ ions acrossmore » the membrane. TM1088 represents the first structure of a two-subunit Trk assembly. Despite the atypical genetics and chain organization of the TM1088 assembly, it shares significant structural homology and an overall quaternary organization with other single-subunit K⁺ gating ring assemblies. This structure provides the first structural insights into what may be an evolutionary ancestor of more modern single-subunit K⁺ gating ring assemblies.« less

The Bmi-1 helix–turn and ring finger domains are required for Bmi-1 antagonism of (–) epigallocatechin-3-gallate suppression of skin cancer cell survival

PubMed Central

Balasubramanian, Sivaprakasam; Scharadin, Tiffany M.; Han, Bingshe; Xu, Wen; Eckert, Richard L.

2016-01-01

The Bmi-1 Polycomb group (PcG) protein is an important epigenetic regulator of chromatin status. Elevated Bmi-1 expression is observed in skin cancer and contributes to cancer cell survival. (–) Epigallocatechin-3-gallate (EGCG), an important green tea-derived cancer prevention agent, reduces Bmi-1 level resulting in reduced skin cancer cell survival. This is associated with increased p21Cip1 and p27Kip1 expression, reduced cyclin, and cyclin dependent kinase expression, and increased cleavage of apoptotic markers. These EGCG-dependent changes are attenuated by vector-mediated maintenance of Bmi-1 expression. In the present study, we identify Bmi-1 functional domains that are required for this response. Bmi-1 expression reverses the EGCG-dependent reduction in SCC-13 cell survival, but Bmi-1 mutants lacking the helix–turn–helix–turn–helix–turn (Bmi-1ΔHT) or ring finger (Bmi-1ΔRF) domains do not reverse the EGCG impact. The reduction in Ring1B ubiquitin ligase activity, observed in the presence of mutant Bmi-1, is associated with reduced ability of these mutants to interact with and activate Ring1B ubiquitin ligase, the major ligase responsible for the ubiquitination of histone H2A during chromatin condensation. This results in less chromatin condensation leading to increased tumor suppressor gene expression and reduced cell survival; thereby making the cells more susceptible to the anti-survival action of EGCG. We further show that these mutants act in a dominant-negative manner to inhibit the action of endogenous Bmi-1. Our results suggest that the HT and RF domains are required for Bmi-1 ability to maintain skin cancer cell survival in response to cancer preventive agents. PMID:25843776

Xylogenesis: Coniferous Trees of Temperate Forests Are Listening to the Climate Tale during the Growing Season But Only Remember the Last Words!1

PubMed Central

2016-01-01

The complex inner mechanisms that create typical conifer tree-ring structure (i.e. the transition from large, thin-walled earlywood cells to narrow, thick-walled latewood cells) were recently unraveled. However, what physiological or environmental factors drive xylogenesis key processes remain unclear. Here, we aim to quantify the influence of seasonal variations in climatic factors on the spectacular changes in the kinetics of wood cell differentiation and in the resulting tree-ring structure. Wood formation was monitored in three sites over 3 years for three coniferous species (Norway spruce [Picea abies], Scots pine [Pinus sylvestris], and silver fir [Abies alba]). Cell differentiation rates and durations were calculated and related to tracheid final dimensions and corresponding climatic conditions. On the one hand, we found that the kinetics of cell enlargement and the final size of the tracheids were not explained by the seasonal changes in climatic factors. On the other hand, decreasing temperatures strongly constrained cell wall deposition rates during latewood formation. However, the influence of temperature was permanently written into tree-ring structure only for the very last latewood cells, when the collapse of the rate of wall deposition was no longer counterbalanced by the increase of its duration. Our results show that the formation of the typical conifer tree-ring structure, in normal climatic conditions, is only marginally driven by climate, suggesting strong developmental control of xylogenesis. The late breakage of the compensatory mechanism at work in the wall deposition process appears as a clue to understand the capacity of the maximum latewood density to record past temperature conditions. PMID:27208048

Xylogenesis: Coniferous Trees of Temperate Forests Are Listening to the Climate Tale during the Growing Season But Only Remember the Last Words!

PubMed

Cuny, Henri E; Rathgeber, Cyrille B K

2016-05-01

The complex inner mechanisms that create typical conifer tree-ring structure (i.e. the transition from large, thin-walled earlywood cells to narrow, thick-walled latewood cells) were recently unraveled. However, what physiological or environmental factors drive xylogenesis key processes remain unclear. Here, we aim to quantify the influence of seasonal variations in climatic factors on the spectacular changes in the kinetics of wood cell differentiation and in the resulting tree-ring structure. Wood formation was monitored in three sites over 3 years for three coniferous species (Norway spruce [Picea abies], Scots pine [Pinus sylvestris], and silver fir [Abies alba]). Cell differentiation rates and durations were calculated and related to tracheid final dimensions and corresponding climatic conditions. On the one hand, we found that the kinetics of cell enlargement and the final size of the tracheids were not explained by the seasonal changes in climatic factors. On the other hand, decreasing temperatures strongly constrained cell wall deposition rates during latewood formation. However, the influence of temperature was permanently written into tree-ring structure only for the very last latewood cells, when the collapse of the rate of wall deposition was no longer counterbalanced by the increase of its duration. Our results show that the formation of the typical conifer tree-ring structure, in normal climatic conditions, is only marginally driven by climate, suggesting strong developmental control of xylogenesis. The late breakage of the compensatory mechanism at work in the wall deposition process appears as a clue to understand the capacity of the maximum latewood density to record past temperature conditions. © 2016 American Society of Plant Biologists. All Rights Reserved.

Standardized limbal epithelial stem cell graft generation and transplantation.

PubMed

Zakaria, Nadia; Koppen, Carina; Van Tendeloo, Viggo; Berneman, Zwi; Hopkinson, Andrew; Tassignon, Marie-José

2010-10-01

To describe a standardized, xenogenic-free protocol for the manufacture of limbal epithelial stem cell grafts and a "no touch" surgical technique for its standardized transplantation. Antwerp University Hospital, Antwerp, Belgium. The limbo-amnion composite graft is generated by cultivating limbal epithelial stem cells on a standardized (thermolysin treated and spongy layer removed) amniotic membrane, stretched within an interlockable amnion ring. The cells are cultured in CnT-20 medium with the addition of 1% human AB serum for a period of 2 weeks. Fibrin glue is applied to the surgically prepared recipient's cornea and in one fluid motion, the composite graft within the amnion ring construct is transferred from culture and positioned onto the graft bed. The required size is cut out at the level of the limbus by means of a trephine and/or microsurgical scissors. The lightweight, plastic interlockable ring offered stability to the graft during culture, transport, and transplantation. The use of the standardized amniotic membrane, within the amnion ring construct, improves reproducibility of the results and therefore heralds elective surgery. Rapid transplantation of a wrinkle-free graft, using a sutureless, “no touch" technique was achieved and this allowed precise tailoring of the graft to the recipient bed. This is the first time a standardized, clinical grade protocol has been described for manufacturing limbal epithelial grafts with an efficient surgical technique that prevents postsurgical graft shrinkage and improves corneal integration. The quick, sutureless, and manipulation-free technique ensured transplantation of viable, proliferating limbal epithelial stem cells.

Divergent climate response on hydraulic-related xylem anatomical traits of Picea abies along a 900-m altitudinal gradient.

PubMed

Castagneri, Daniele; Petit, Giai; Carrer, Marco

2015-12-01

Climate change can induce substantial modifications in xylem structure and water transport capacity of trees exposed to environmental constraints. To elucidate mechanisms of xylem plasticity in response to climate, we retrospectively analysed different cell anatomical parameters over tree-ring series in Norway spruce (Picea abies L. Karst.). We sampled 24 trees along an altitudinal gradient (1200, 1600 and 2100 m above sea level, a.s.l.) and processed 2335 ± 1809 cells per ring. Time series for median cell lumen area (MCA), cell number (CN), tree-ring width (RW) and tree-ring-specific hydraulic conductivity (Kr) were crossed with daily temperature and precipitation records (1926-2011) to identify climate influence on xylem anatomical traits. Higher Kr at the low elevation site was due to higher MCA and CN. These variables were related to different aspects of intra-seasonal climatic variability under different environmental conditions, with MCA being more sensitive to summer precipitation. Winter precipitation (snow) benefited most parameters in all the sites. Descending the gradient, sensitivity of xylem features to summer climate shifted mostly from temperature to precipitation. In the context of climate change, our results indicate that higher summer temperatures at high elevations will benefit cell production and xylem hydraulic efficiency, whereas reduced water availability at lower elevations could negatively affect tracheids enlargement and thus stem capacity to transport water. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Acceptability of the vaginal contraceptive ring among adolescent women.

PubMed

Terrell, Lekeisha R; Tanner, Amanda E; Hensel, Devon J; Blythe, Margaret J; Fortenberry, J Dennis

2011-08-01

Although underutilized, the vaginal contraceptive ring has several advantages over other contraceptive methods that could benefit adolescents. We examined factors that may influence willingness to try the vaginal ring including: sexual and contraceptive history, genital comfort, and vaginal ring characteristics. Cross sectional Midwestern adolescent health clinics Adolescent women (N = 200; 14-18 years; 89% African-American) INTERVENTIONS/MAIN OUTCOME MEASURES: All participants received education about the vaginal ring and viewed pictures demonstrating insertion; they then completed a visual/audio computer-assisted self interview. The primary outcome variable, willingness to try the vaginal ring, was a single Likert-scale item. Over half the participants reported knowledge of the vaginal ring with healthcare providers identified as the most important source of contraceptive information. Comfort with one's genitals, insertion and removal, using alternative methods of insertion, and knowing positive method characteristics were significantly associated with willingness to try the vaginal ring. A decreased willingness to try the vaginal ring was related to concerns of the ring getting lost inside or falling out of the vagina. Willingness to try the ring was associated with positive feelings about genitals (e.g., comfort with appearance, hygiene, function). Thus, to increase willingness to try the vaginal ring among adolescents, providers should make it common practice to discuss basic female reproductive anatomy, raise awareness about female genital health and address concerns about their genitals. Providers can offer alternative insertion techniques (e.g., gloves) to make use more accessible. These strategies may increase vaginal ring use among adolescents. 2011 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

Regio- and stereoselective synthesis of pregnane-fused isoxazolines by nitril-oxide/alkene 1,3-dipolar cycloaddition and an evaluation of their cell-growth inhibitory effect in vitro

NASA Astrophysics Data System (ADS)

Mótyán, Gergő; Baji, Ádám; Zupkó, István; Frank, Éva

2016-04-01

Efficient syntheses of some pregnane-fused isoxazolines from 16-dehydropregnenolone acetate with different arylnitrile oxides were carried out by 1,3-dipolar cycloadditions. The intermolecular ring-closures occurred in a highly regio- and stereoselective manner permitting the formation of a single 16α,17α-condensed diastereomer in which the O terminus of the nitrile oxide dipole is attached to C-17 of the sterane core. The conversions were found to be affected significantly by the electronic character of the substituents on the aromatic moiety of the 1,3-dipoles. Deacetylation of the primary products resulted in the corresponding 3β-OH analogs. All of the synthesized compounds were subjected to in vitro pharmacological studies for the determination of their antiproliferative effects on four breast cancer cell lines (MCF7, T47D, MDA-MB-231 and MDA-MB-361).

Adherence to Survivorship Care Guidelines in Health Care Providers for Non-Small Cell Lung Cancer and Colorectal Cancer Survivor Care

ClinicalTrials.gov

2017-04-05

Adenocarcinoma of the Lung; Mucinous Adenocarcinoma of the Colon; Mucinous Adenocarcinoma of the Rectum; Signet Ring Adenocarcinoma of the Colon; Signet Ring Adenocarcinoma of the Rectum; Squamous Cell Lung Cancer; Stage I Colon Cancer; Stage I Rectal Cancer; Stage IA Non-small Cell Lung Cancer; Stage IB Non-small Cell Lung Cancer; Stage IIA Colon Cancer; Stage IIA Non-small Cell Lung Cancer; Stage IIA Rectal Cancer; Stage IIB Colon Cancer; Stage IIB Non-small Cell Lung Cancer; Stage IIB Rectal Cancer; Stage IIC Colon Cancer; Stage IIC Rectal Cancer; Stage IIIA Colon Cancer; Stage IIIA Non-small Cell Lung Cancer; Stage IIIA Rectal Cancer; Stage IIIB Colon Cancer; Stage IIIB Non-small Cell Lung Cancer; Stage IIIB Rectal Cancer; Stage IIIC Colon Cancer; Stage IIIC Rectal Cancer

Conformation analysis of 1″,4″-Dispirocyclohexane-6,6'-bis(benzothiazoline): Combined IR, Raman, XRD and DFT approach.

PubMed

P J, Arathi; Gupta, Parth; Babu N, Jagadeesh; C N, Sundaresan; Venkatnarayan, Ramanathan

2016-03-15

The subject of the study is the structure and conformation of 1″,4″-Dispiro-cyclohexane-6,6'-bis(benzothiazoline), a dispiro compound that has a cyclohexyl ring flanked by two benzothiazoline rings on either side. Using single crystal X-ray diffraction measurements, Infra-red absorption, and Raman spectroscopy techniques, it is found that the central cyclohexyl ring assumes the chair conformation and the sulfur, nitrogen atoms in both the benzothiazole rings are in the trans configurations. The experimental findings are further corroborated by geometry optimization and frequency calculations at B3LYP/6-311++G** level of theory using Gaussian 09 suite of program. Copyright © 2015 Elsevier B.V. All rights reserved.

A radial map of multi-whisker correlation selectivity in the rat barrel cortex

PubMed Central

Estebanez, Luc; Bertherat, Julien; Shulz, Daniel E.; Bourdieu, Laurent; Léger, Jean- François

2016-01-01

In the barrel cortex, several features of single-whisker stimuli are organized in functional maps. The barrel cortex also encodes spatio-temporal correlation patterns of multi-whisker inputs, but so far the cortical mapping of neurons tuned to such input statistics is unknown. Here we report that layer 2/3 of the rat barrel cortex contains an additional functional map based on neuronal tuning to correlated versus uncorrelated multi-whisker stimuli: neuron responses to uncorrelated multi-whisker stimulation are strongest above barrel centres, whereas neuron responses to correlated and anti-correlated multi-whisker stimulation peak above the barrel–septal borders, forming rings of multi-whisker synchrony-preferring cells. PMID:27869114

A radial map of multi-whisker correlation selectivity in the rat barrel cortex.

PubMed

Estebanez, Luc; Bertherat, Julien; Shulz, Daniel E; Bourdieu, Laurent; Léger, Jean-François

2016-11-21

In the barrel cortex, several features of single-whisker stimuli are organized in functional maps. The barrel cortex also encodes spatio-temporal correlation patterns of multi-whisker inputs, but so far the cortical mapping of neurons tuned to such input statistics is unknown. Here we report that layer 2/3 of the rat barrel cortex contains an additional functional map based on neuronal tuning to correlated versus uncorrelated multi-whisker stimuli: neuron responses to uncorrelated multi-whisker stimulation are strongest above barrel centres, whereas neuron responses to correlated and anti-correlated multi-whisker stimulation peak above the barrel-septal borders, forming rings of multi-whisker synchrony-preferring cells.

ARIEL e-LINAC: Commissioning and Development

NASA Astrophysics Data System (ADS)

Laxdal, R. E.; Zvyagintsev, V.

2016-09-01

A superconducting electron Linac (e-Linac) will be a part of the ARIEL facility for the production of radioactive ion beams (RIB) at TRIUMF. The e-Linac will consist of five 1.3GHz 9-cell cavities in three cryomodules delivering a 50MeV 10mA beam. The baseline operation will be single pass but a re-circulating ring is planned to allow either energy boost or energy recovery operation. The first stage of the accelerator which consists of two cryomodules has been successfully commissioned in 2014. The paper will discuss the superconducting radio-frequency (SRF) challenges of the accelerator. Cavities, crymodules and RF system design, preparation, and performance will be presented.

Selective interactions of trivalent cations Fe³⁺, Al³⁺ and Cr³⁺ turn on fluorescence in a naphthalimide based single molecular probe.

PubMed

Janakipriya, Subramaniyan; Chereddy, Narendra Reddy; Korrapati, Purnasai; Thennarasu, Sathiah; Mandal, Asit Baran

2016-01-15

Synthesis and fluorescence turn-on behavior of a naphthalimide based probe is described. Selective interactions of trivalent cations Fe(3+), Al(3+) or Cr(3+) with probe 1 inhibit the PET operating in the probe, and thereby, permit the detection of these trivalent cations present in aqueous samples and live cells. Failure of other trivalent cations (Eu(3+), Gd(3+) and Nb(3+)) to inhibit the PET process in 1 demonstrates the role of chelating ring size vis-à-vis ionic radius in the selective recognition of specific metal ions. Copyright © 2015 Elsevier B.V. All rights reserved.

Discovery of B ring propellers in Cassini UVIS and ISS

NASA Astrophysics Data System (ADS)

Sremcevic, M.; Stewart, G.; Albers, N.; Esposito, L. W.

2011-12-01

One of the successes of the planetary ring theory has been the theoretical prediction of gravitational signatures of bodies embedded in the rings, and their subsequent detection in Cassini data. Bodies within the rings perturb the nearby ring material, and the orbital shear forms a two-armed structure -- dubbed a ``propeller'' -- which is centered at the embedded body. Although direct evidence of the present body or moonlet is still lacking, the observations of their propeller signatures has proved as an indispensable method to extend our knowledge about ring structure and dynamics. So far, propellers have been successfully detected within Saturn's A ring in two populations: a group of small and numerous propellers interior to the Encke gap forming belts, and by far less numerous but larger propellers exterior to Pan's orbit. Although there have been hints of propellers present within the B ring, or even C ring, their detection is less certain (e.g. neither has a single propeller been seen twice, nor has the ubiquitous two armed structure been observed). In this paper we present evidence for the existence of propellers in Saturn's B ring by combining data from Cassini Ultraviolet Imaging Spectrograph (UVIS) and Imaging Science Subsystem (ISS) experiments. A single object is observed for 5 years of Cassini data. The object is seen as a very elongated bright stripe (40 degrees wide) in unlit Cassini images, and dark stripe in lit geometries. In total we report observing the feature in images at 18 different epochs between 2005 and 2010. In UVIS occultations we observe the feature as an optical depth depletion in 14 out of 93 occultation cuts at corrotating longitudes compatible with imaging data. Combining the available Cassini data we infer that the object is a partial gap located at a=112,921km embedded in the high optical depth region of the B ring. The gap moves at Kepler speed appropriate for its radial location. Radial offsets of the gap locations in UVIS occultations are consistent with an asymmetric propeller shape. The asymmetry of the observed shape is most likely a consequence of the strong surface mass density gradient, as the feature is located at an edge between high and relatively low optical depth. From the radial separation of the propeller wings we estimate that the embedded body is about 1.5km in size. We estimate that there are possibly dozen up to 100 other propeller objects in Saturn's B ring. Since the discovered body sits at an edge of a dense ringlet within the B ring this suggests a novel mechanism for the up to now illusive B ring irregular shape of alternating high and low optical depth ringlets. We propose that the long standing search for the mechanism that maintains the B ring irregular shape may have its explanation in the presence of many embedded bodies that shepherd the individual B ring ringlets.

Actin turnover maintains actin filament homeostasis during cytokinetic ring contraction

PubMed Central

Palani, Saravanan; Sommese, Ruth; Kamnev, Anton; Hatano, Tomoyuki; Sivaramakrishnan, Sivaraj

2017-01-01

Cytokinesis in many eukaryotes involves a tension-generating actomyosin-based contractile ring. Many components of actomyosin rings turn over during contraction, although the significance of this turnover has remained enigmatic. Here, using Schizosaccharomyces japonicus, we investigate the role of turnover of actin and myosin II in its contraction. Actomyosin ring components self-organize into ∼1-µm-spaced clusters instead of undergoing full-ring contraction in the absence of continuous actin polymerization. This effect is reversed when actin filaments are stabilized. We tested the idea that the function of turnover is to ensure actin filament homeostasis in a synthetic system, in which we abolished turnover by fixing rings in cell ghosts with formaldehyde. We found that these rings contracted fully upon exogenous addition of a vertebrate myosin. We conclude that actin turnover is required to maintain actin filament homeostasis during ring contraction and that the requirement for turnover can be bypassed if homeostasis is achieved artificially. PMID:28655757

Nonmedially assembled F-actin cables incorporate into the actomyosin ring in fission yeast

PubMed Central

Huang, Junqi; Huang, Yinyi; Yu, Haochen; Subramanian, Dhivya; Padmanabhan, Anup; Thadani, Rahul; Tao, Yaqiong; Tang, Xie; Wedlich-Soldner, Roland

2012-01-01

In many eukaryotes, cytokinesis requires the assembly and constriction of an actomyosin-based contractile ring. Despite the central role of this ring in cytokinesis, the mechanism of F-actin assembly and accumulation in the ring is not fully understood. In this paper, we investigate the mechanism of F-actin assembly during cytokinesis in Schizosaccharomyces pombe using lifeact as a probe to monitor actin dynamics. Previous work has shown that F-actin in the actomyosin ring is assembled de novo at the division site. Surprisingly, we find that a significant fraction of F-actin in the ring was recruited from formin-Cdc12p nucleated long actin cables that were generated at multiple nonmedial locations and incorporated into the ring by a combination of myosin II and myosin V activities. Our results, together with findings in animal cells, suggest that de novo F-actin assembly at the division site and directed transport of F-actin cables assembled elsewhere can contribute to ring assembly. PMID:23185032

Multi-stage FE simulation of hot ring rolling

NASA Astrophysics Data System (ADS)

Wang, C.; Geijselaers, H. J. M.; van den Boogaard, A. H.

2013-05-01

As a unique and important member of the metal forming family, ring rolling provides a cost effective process route to manufacture seamless rings. Applications of ring rolling cover a wide range of products in aerospace, automotive and civil engineering industries [1]. Above the recrystallization temperature of the material, hot ring rolling begins with the upsetting of the billet cut from raw stock. Next a punch pierces the hot upset billet to form a hole through the billet. This billet, referred to as preform, is then rolled by the ring rolling mill. For an accurate simulation of hot ring rolling, it is crucial to include the deformations, stresses and strains from the upsetting and piercing process as initial conditions for the rolling stage. In this work, multi-stage FE simulations of hot ring rolling process were performed by mapping the local deformation state of the workpiece from one step to the next one. The simulations of upsetting and piercing stages were carried out by 2D axisymmetric models using adaptive remeshing and element erosion. The workpiece for the ring rolling stage was subsequently obtained after performing a 2D to 3D mapping. The commercial FE package LS-DYNA was used for the study and user defined subroutines were implemented to complete the control algorithm. The simulation results were analyzed and also compared with those from the single-stage FE model of hot ring rolling.

THE SCHOOL PARK.

ERIC Educational Resources Information Center

FISCHER, JOHN H.

TO ASSIST IN DESEGREGATION, VARIOUS MODELS FOR THE SCHOOL PARK ARE PROPOSED--(1) ASSEMBLING ALL STUDENTS AND SCHOOLS OF A SMALL OR MEDIUM-SIZED COMMUNITY ON A SINGLE CAMPUS, (2) SERVING ONE SECTION OF A LARGE CITY, (3) CENTERING ALL SCHOOL FACILITIES FOR A SINGLE LEVEL OF EDUCATION ON A SINGLE SITE, AND (4) ESTABLISHING RINGS OF SCHOOL PARKS ABOUT…

a Global Registration Algorithm of the Single-Closed Ring Multi-Stations Point Cloud

NASA Astrophysics Data System (ADS)

Yang, R.; Pan, L.; Xiang, Z.; Zeng, H.

2018-04-01

Aimed at the global registration problem of the single-closed ring multi-stations point cloud, a formula in order to calculate the error of rotation matrix was constructed according to the definition of error. The global registration algorithm of multi-station point cloud was derived to minimize the error of rotation matrix. And fast-computing formulas of transformation matrix with whose implementation steps and simulation experiment scheme was given. Compared three different processing schemes of multi-station point cloud, the experimental results showed that the effectiveness of the new global registration method was verified, and it could effectively complete the global registration of point cloud.

Chiral Sulfoxide-Induced Single Turn Peptide α-Helicity

PubMed Central

Zhang, Qingzhou; Jiang, Fan; Zhao, Bingchuan; Lin, Huacan; Tian, Yuan; Xie, Mingsheng; Bai, Guoyun; Gilbert, Adam M.; Goetz, Gilles H.; Liras, Spiros; Mathiowetz, Alan A.; Price, David A.; Song, Kun; Tu, Meihua; Wu, Yujie; Wang, Tao; Flanagan, Mark E.; Wu, Yun-Dong; Li, Zigang

2016-01-01

Inducing α-helicity through side-chain cross-linking is a strategy that has been pursued to improve peptide conformational rigidity and bio-availability. Here we describe the preparation of small peptides tethered to chiral sulfoxide-containing macrocyclic rings. Furthermore, a study of structure-activity relationships (SARs) disclosed properties with respect to ring size, sulfur position, oxidation state, and stereochemistry that show a propensity to induce α-helicity. Supporting data include circular dichroism spectroscopy (CD), NMR spectroscopy, and a single crystal X-ray structure for one such stabilized peptide. Finally, theoretical studies are presented to elucidate the effect of chiral sulfoxides in inducing backbone α-helicity. PMID:27934919

Broadband impedance calculations and single bunch instabilities estimations of of the HLS-II storage ring

NASA Astrophysics Data System (ADS)

Zhang, Qing-Kun; Wang, Lin; Li, Wei-Min; Gao, Wei-Wei

2015-12-01

The upgrade project of the Hefei Light Source storage ring is under way. In this paper, the broadband impedances of resistive wall and coated ceramic vacuum chamber are calculated using the analytic formula, and the wake fields and impedances of other designed vacuum chambers are simulated by CST code, and then a broadband impedance model is obtained. Using the theoretical formula, longitudinal and transverse single bunch instabilities are discussed. With the carefully-designed vacuum chamber, we find that the thresholds of the beam instabilities are higher than the beam current goal. Supported by Natural Science Foundation of China (11175182, 11175180)

Caffeine and Sugars Interact in Aqueous Solutions: A Simulation and NMR Study

PubMed Central

Tavagnacco, Letizia; Engström, Olof; Schnupf, Udo; Saboungi, Marie-Louise; Himmel, Michael; Widmalm, Göran; Cesàro, Attilio; Brady, John W.

2012-01-01

Molecular dynamics simulations were carried out on several systems of caffeine interacting with simple sugars. These included a single caffeine molecule in a 3 molal solution of α-D-glucopyranose, at a caffeine concentration of 0.083 molal; a single caffeine in a 3 molal solution of β-D-glucopyranose, and a single caffeine molecule in a 1.08 molal solution of sucrose (table sugar). Parallel Nuclear Magnetic Resonance titration experiments were carried out on the same solutions under similar conditions. Consistent with previous thermodynamic experiments, the sugars were found to have an affinity for the caffeine molecules in both the simulations and experiments, and that the binding in these complexes occurs by face-to-face stacking of the hydrophobic triad of protons of the pyranose rings against the caffeine face, rather than by hydrogen bonding. For the disaccharide, the binding occurs via stacking of the glucose ring against the caffeine, with a lesser affinity for the fructose observed. These findings are consistent with the association being driven by hydrophobic hydration, and are similar to the previously observed binding of glucose rings to various other planar molecules, including indole, serotonin, and phenol. PMID:22897449

Caffeine and sugars interact in aqueous solutions: a simulation and NMR study.

PubMed

Tavagnacco, Letizia; Engström, Olof; Schnupf, Udo; Saboungi, Marie-Louise; Himmel, Michael; Widmalm, Göran; Cesàro, Attilio; Brady, John W

2012-09-27

Molecular dynamics simulations were carried out on several systems of caffeine interacting with simple sugars. These included a single caffeine molecule in a 3 m solution of α-D-glucopyranose, at a caffeine concentration of 0.083 m, a single caffeine in a 3 m solution of β-D-glucopyranose, and a single caffeine molecule in a 1.08 m solution of sucrose (table sugar). Parallel nuclear magnetic resonance titration experiments were carried out on the same solutions under similar conditions. Consistent with previous thermodynamic experiments, the sugars were found to have an affinity for the caffeine molecules in both the simulations and experiments, and the binding in these complexes occurs by face-to-face stacking of the hydrophobic triad of protons of the pyranose rings against the caffeine face, rather than by hydrogen bonding. For the disaccharide, the binding occurs via stacking of the glucose ring against the caffeine, with a lesser affinity for the fructose observed. These findings are consistent with the association being driven by hydrophobic hydration and are similar to the previously observed binding of glucose rings to various other planar molecules, including indole, serotonin, and phenol.

On the dual-cone nature of the conical refraction phenomenon.

PubMed

Turpin, A; Loiko, Yu; Kalkandjiev, T K; Tomizawa, H; Mompart, J

2015-04-15

In conical refraction (CR), a focused Gaussian input beam passing through a biaxial crystal and parallel to one of the optic axes is transformed into a pair of concentric bright rings split by a dark (Poggendorff) ring at the focal plane. Here, we show the generation of a CR transverse pattern that does not present the Poggendorff fine splitting at the focal plane, i.e., it forms a single light ring. This light ring is generated from a nonhomogeneously polarized input light beam obtained by using a spatially inhomogeneous polarizer that mimics the characteristic CR polarization distribution. This polarizer allows modulating the relative intensity between the two CR light cones in accordance with the recently proposed dual-cone model of the CR phenomenon. We show that the absence of interfering rings at the focal plane is caused by the selection of one of the two CR cones.

Photometric studies of Saturn's ring and eclipses of the Galilean satellites

NASA Technical Reports Server (NTRS)

Brunk, W. E.

1972-01-01

Reliable data defining the photometric function of the Saturn ring system at visual wavelengths are interpreted in terms of a simple scattering model. To facilitate the analysis, new photographic photometry of the ring has been carried out and homogeneous measurements of the mean surface brightness are presented. The ring model adopted is a plane parallel slab of isotropically scattering particles; the single scattering albedo and the perpendicular optical thickness are both arbitrary. Results indicate that primary scattering is inadequate to describe the photometric properties of the ring: multiple scattering predominates for all angles of tilt with respect to the Sun and earth. In addition, the scattering phase function of the individual particles is significantly anisotropic: they scatter preferentially towards the sun. Photoelectric photometry of Ganymede during its eclipse by Jupiter indicate that neither a simple reflecting-layer model nor a semi-infinite homogeneous scattering model provides an adequate physical description of the Jupiter atmosphere.

Variable diameter CO₂ laser ring-cutting system adapted to a zoom microscope for applications on polymer tapes.

PubMed

Förster, Erik; Bohnert, Patrick; Kraus, Matthias; Kilper, Roland; Müller, Ute; Buchmann, Martin; Brunner, Robert

2016-11-20

This paper presents the conception and implementation of a variable diameter ring-cutting system for a CO₂ laser with a working wavelength of 10.6 μm. The laser-cutting system is adapted to an observation zoom microscope for combined use and is applicable for the extraction of small circular areas from polymer films, such as forensic adhesive tapes in a single shot. As an important characteristic for our application, the variable diameter ring-cutting system provides telecentricity in the target area. Ring diameters are continuously tunable between 500 μm and 2 mm. A minimum width of less than 20 μm was found for the ring profile edge. The basic characteristics of the system, including telecentricity, were experimentally evaluated and demonstrated by cutting experiments on different polymer tapes and further exemplary samples.

Metal-chelating polymers by anionic ring-opening polymerization and their use in quantitative mass cytometry.

PubMed

Illy, Nicolas; Majonis, Daniel; Herrera, Isaac; Ornatsky, Olga; Winnik, Mitchell A

2012-08-13

Metal-chelating polymers (MCPs) are important reagents for multiplexed immunoassays based on mass cytometry. The role of the polymer is to carry multiple copies of individual metal isotopes, typically as lanthanide ions, and to provide a reactive functionality for convenient attachment to a monoclonal antibody (mAb). For this application, the optimum combination of chain length, backbone structure, end group, pendant groups, and synthesis strategy has yet to be determined. Here we describe the synthesis of a new type of MCP based on anionic ring-opening polymerization of an activated cyclopropane (the diallyl ester of 1,1-cyclopropane dicarboxylic acid) using a combination of 2-furanmethanethiol and a phosphazene base as the initiator. This reaction takes place with rigorous control over molecular weight, yielding a polymer with a narrow molecular weight distribution, reactive pendant groups for introducing a metal chelator, and a functional end group with orthogonal reactivity for attaching the polymer to the mAbs. Following the ring-opening polymerization, a two-step transformation introduced diethylenetriaminepentaacetic acid (DTPA) chelating groups on each pendant group. The polymers were characterized by NMR, size exclusion chromatography (SEC), and thermogravimetric analysis (TGA). The binding properties toward Gd(3+) as a prototypical lanthanide (Ln) ion were also studied by isothermal titration calorimetry (ITC). Attachment to a mAb involves a Diels-Alder reaction of the terminal furan with a bismaleimide, followed by a Michael addition of a thiol on the mAb, generated by mild reduction of a disulfide bond in the hinge region. Polymer samples with a number average degree of polymerization of 35, with a binding capacity of 49.5 ± 6 Ln(3+) ions per chain, were loaded with 10 different types of Ln ions and conjugated to 10 different mAbs. A suite of metal-tagged Abs was tested by mass cytometry in a 10-plex single cell analysis of human adult peripheral blood, allowing us to quantify the antibody binding capacity of 10 different cell surface antigens associated with specific cell types.