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Sample records for actinomycin x2 production

  1. A marine-derived Streptomyces sp. MS449 produces high yield of actinomycin X2 and actinomycin D with potent anti-tuberculosis activity.

    PubMed

    Chen, Caixia; Song, Fuhang; Wang, Qian; Abdel-Mageed, Wael M; Guo, Hui; Fu, Chengzhang; Hou, Weiyuan; Dai, Huanqin; Liu, Xueting; Yang, Na; Xie, Feng; Yu, Ke; Chen, Ruxian; Zhang, Lixin

    2012-08-01

    In the course of our screening program for anti-Mycobacterium bovis bacillus Calmette-Guérin (BCG) and anti-Mycobacterium tuberculosis H37Rv (MTB H37Rv) agents from our marine natural product library, a newly isolated actinomycete strain, designated as MS449, was picked out for further investigation. The strain MS449, isolated from a sediment sample collected from South China Sea, produced actinomycin X(2) and actinomycin D in substantial quantities, which showed strong inhibition of BCG and MTB H37Rv. The structures of actinomycins were elucidated by nuclear magnetic resonance and mass spectrometric analysis. The strain MS449 was taxonomically characterized on the basis of morphological and phenotypic characteristics, genotypic data, and phylogenetic analysis. The 16S rRNA gene sequence of the strain was determined and a database search indicated that the strain was closely associated with the type strain of Streptomyces avermitilis (99.7 % 16S rRNA gene similarity). S. avermitilis has not been previously reported to produce actinomycins. The marine-derived strain of Streptomyces sp. MS449 produced notably higher quantities of actinomycin X(2) (1.92 mg/ml) and actinomycin D (1.77 mg/ml) than previously reported actinomycins producing strains. Thus, MS449 was considered of great potential as a new industrial producing strain of actinomycin X(2) and actinomycin D.

  2. The effect of space flight on the production of actinomycin D by Streptomyces plicatus.

    PubMed

    Lam, K S; Gustavson, D R; Pirnik, D L; Pack, E; Bulanhagui, C; Mamber, S W; Forenza, S; Stodieck, L S; Klaus, D M

    2002-12-01

    The effect of space flight on production of the antibiotic actinomycin D by Streptomyces plicatus WC56452 was examined onboard the US Space Shuttle mission STS-80. Paired space flight and ground control samples were similarly prepared using identical hardware, media, and inoculum. The cultures were grown in defined and complex media under dark, anaerobic, thermally controlled (20 degrees C) conditions with samples fixed after 7 and 12 days in orbit, and viable residuals maintained through landing at 17 days, 15 h. Postflight analyses indicated that space flight had reduced the colony-forming unit (CFU) per milliliter count of S. plicatus and increased the specific productivity (pg CFU(-1)) of actinomycin D. The antibiotic compound itself was not affected, but its production time course was altered in space. Viable flight samples also maintained their sporulation ability when plated on agar medium postflight, while the residual ground controls did not sporulate.

  3. [Separation of the biosynthesis products of a mutant strain of Actinomyces chrysomallus var. carotenoides and the identification of actinomycin antibiotics].

    PubMed

    Sverdlova, A N; Nefelova, M V; Silaev, A B

    1979-01-01

    An orange antibiotically active substance isolated from the mycelium of a mutant strain of Actinomyces chrysomallus var. carotenoides was identified as a mixture of actinomycins according to its light absorption spectra, circular dichroism spectra, IR spectra and chromatographic comparison with the standard samples. A scheme for successive extraction of the biologically active substances from the mycelium resulting in isolation of a fraction enriched with antibiotic substances and a fraction enriched with pigments is presented. A method for separation and purification of 3 groups of biologically active substances from the mycelium enriched extract was developed.

  4. Liposome-encapsulated actinomycin for cancer chemotherapy

    DOEpatents

    Rahman, Yueh-Erh; Cerny, Elizabeth A.

    1976-01-01

    An improved method is provided for chemotherapy of malignant tumors by injection of antitumor drugs. The antitumor drug is encapsulated within liposomes and the liposomes containing the encapsulated drug are injected into the body. The encapsulated drug penetrates into the tumor cells where the drug is slowly released and induces degeneration and death of the tumor cells, while any toxicity to the host body is reduced. Liposome encapsulation of actinomycin D has been found to be particularly effective in treating cancerous abdominal tumors, while drastically reducing the toxicity of actinomycin D to the host.

  5. [Sedimentation characteristics of virion RNA of Machupo virus reproducing in the presence of actinomycin D].

    PubMed

    Golubev, V P; Scheslenok, E P; Finskaia, N N; Lukashevich, I S

    1985-06-01

    Actinomycin D treatment (0.005-05 g/ml) of Vero and BHK-21 cells infected with Machupo virus suppressed the synthesis of ribosomal RNAs but did not affect the production of infectious Machupo virus. Virion RNAs contained 3 high molecular weight RNA species: 28-31 S, 22-24 S and 18 S. In the presence of actinomycin D [3H]-uridine incorporated only in 30-31 S and 22-24 S RNA species. The data are supported by previous results which show that Machupo virus genome contains two RNA species: "large" (30-31 S) and "small" (22-24 S).

  6. Streptomyces-derived actinomycin D inhibits biofilm formation by Staphylococcus aureus and its hemolytic activity.

    PubMed

    Lee, Jin-Hyung; Kim, Yong-Guy; Lee, Kayeon; Kim, Chang-Jin; Park, Dong-Jin; Ju, Yoonjung; Lee, Jae-Chan; Wood, Thomas K; Lee, Jintae

    2016-01-01

    Staphylococcus aureus is a versatile human pathogen that produces diverse virulence factors, and its biofilm cells are difficult to eradicate due to their inherent ability to tolerate antibiotics. The anti-biofilm activities of the spent media of 252 diverse endophytic microorganisms were investigated using three S. aureus strains. An attempt was made to identify anti-biofilm compounds in active spent media and to assess their anti-hemolytic activities and hydrophobicities in order to investigate action mechanisms. Unlike other antibiotics, actinomycin D (0.5 μg ml(-1)) from Streptomyces parvulus significantly inhibited biofilm formation by all three S. aureus strains. Actinomycin D inhibited slime production in S. aureus and it inhibited hemolysis by S. aureus and caused S. aureus cells to become less hydrophobic, thus supporting its anti-biofilm effect. In addition, surface coatings containing actinomycin D prevented S. aureus biofilm formation on glass surfaces. Given these results, FDA-approved actinomycin D warrants further attention as a potential antivirulence agent against S. aureus infections. PMID:26785934

  7. Effects of Actinomycin D and Ultraviolet and Ionizing Radiation on Pichinde Virus

    PubMed Central

    Carter, Michael F.; Murphy, Frederick A.; Brunschwig, J. Pierre; Noonan, Christine; Rawls, William E.

    1973-01-01

    Actinomycin D (0.05 μg/ml) suppresses the synthesis of ribosomal RNA of baby hamster kidney (BHK21) cells. The production of infectious Pichinde virus was enhanced in the presence of actinomycin D, although the production of virus particles was not substantially different from cultures inoculated in the absence of the drug. By prelabeling BHK21 cells with 3H-uridine and then allowing the virus to replicate in the presence of actinomycin D, it was possible to show that ribosomal RNA synthesized prior to infection was incorporated into the virion. A single-hit kinetics of inactivation of Pichinde virus was observed with ultraviolet light, suggesting that the virus contains only a single copy of genome per virion. Comparison of the inactivation kinetics by gamma irradiation of Pichinde virus with Sindbis and rubella virus indicated that the radiosensitive genome of Pichinde virus was about 6 × 106 to 8 × 106 daltons. This value is greater than the 3.2 × 106 daltons which was estimated by biochemical analysis. One possible explanation considered is that the ribosomal RNA of host cell origin is functional and accounts for the differences in genome size estimated by the two methods. PMID:4199107

  8. Actinomycin D specifically inhibits the interaction between transcription factor Sp1 and its binding site.

    PubMed

    Czyz, M; Gniazdowski, M

    1998-01-01

    The mode of action of many anticancer drugs involves DNA interactions. We here examine the ability of actinomycin D to alter the specific binding of transcription factors Spl and NFkappaB to their DNA sequences. Employing an electrophoretic mobility shift assay, it is shown that actinomycin D inhibits complex formation between nuclear proteins present in the extracts from stimulated human umbilical vein endothelial cells and the Sp1-binding site. Actinomycin D is also able to induce disruption of preformed DNA-protein complexes, pointing to the importance of an equilibrium of three components: actinomycin D, protein and DNA for drug action. The effect of actinomycin D is sequence-specific, since no inhibition is observed for interaction of nuclear proteins with the NFkappaB binding site. The results support the view that DNA-binding drugs displaying high sequence-selectivity can exhibit distinct effects on the interaction between DNA and different DNA-binding proteins. PMID:9701497

  9. Treatment of tumor-bearing dogs with actinomycin D.

    PubMed

    Hammer, A S; Couto, C G; Ayl, R D; Shank, K A

    1994-01-01

    Fifty dogs with advanced malignancies were treated with actinomycin D at doses ranging from 0.5 to 1.1 mg/m2 every 3 weeks. The greatest number of responses was noted in dogs with lymphoma, including dogs that had received prior chemotherapy. Other responding tumor types included anal sac adenocarcinoma, perianal adenocarcinoma, squamous cell carcinoma, thyroid carcinoma, and transitional cell carcinoma. The median time to maximum response for dogs with lymphoma was 7 days, with a median duration of 42 days. Gastrointestinal toxicity was the most frequently observed side effect. A dose of 0.6 to 0.7 mg/m2 appears to be appropriate for treating various malignancies in dogs. PMID:8064663

  10. Effects of actinomycin D on developing hamster molar tooth germs in vitro.

    PubMed

    Lyaruu, D M; van Duin, M A; Bervoets, T J; Wöltgens, J H; Bronckers, A L

    1997-02-01

    The aim of this study was to evaluate the toxic effects of actinomycin D on the developing hamster tooth germ in organ culture. Hamster tooth germs during early secretory amelogenesis were exposed in vitro for 24 h to 10(-9) M-5 x 10(-5) M actinomycin D. Actinomycin D dose-dependently (> or = 10(-7) M) decreased the tooth germ dry weight but mineralization was affected only by doses > or = 10(-5) M. However, the uptakes of TCA-insoluble 32P and [3H]thymidine were significantly reduced dose-dependently from > or = 10(-8) M actinomycin D, indicating that the drug inhibits the synthesis of phosphate-containing macromolecules as well as DNA synthesis. Histologically, 10(-8) M actinomycin D was the lowest dose which was not toxic to any cell type in the developing tooth germ. At 10(-7) M actinomycin D, the most sensitive cells were the proliferating pre-odontoblasts followed by pre-ameloblasts; the mature secretory ameloblasts and odontoblasts appeared unaffected. Higher doses resulted in increased cytotoxicity to the secretory cells and, eventually, total degeneration of most cells. The data suggest that children treated for cancer during tooth development using anti-chemotherapy cocktails containing actinomycin D (serum levels > 10(-7) M) may develop defects later on in the mature dentition as a direct consequence of the toxicity of the drug to the tooth organ.

  11. New Metabolites and Bioactive Actinomycins from Marine-Derived Streptomyces sp. ZZ338

    PubMed Central

    Zhang, Xiufang; Ye, Xuewei; Chai, Weiyun; Lian, Xiao-Yuan; Zhang, Zhizhen

    2016-01-01

    An extract prepared from the culture of a marine-derived actinomycete Streptomyces sp. ZZ338 was found to have significant antimicrobial and antiproliferative activities. A chemical investigation of this active extract resulted in the isolation of three known bioactive actinomycins (1–3) and two new metabolites (4 and 5). The structures of the isolated compounds were identified as actinomycins D (1), V (2), X0β (3), 2-acetylamino-3-hydroxyl-4-methyl-benzoic acid methyl ester (4), and N-1S-(4-methylaminophenylmethyl)-2-oxo-propyl acetamide (5) based on their nuclear magnetic resonance (NMR) and high resolution electrospray ionization mass spectroscopy (HRESIMS) data as well as their optical rotation. This class of new compound 5 had never before been found from a natural resource. Three known actinomycins showed activities in inhibiting the proliferation of glioma cells and the growth of methicillin-resistant Staphylococcus aureus, Escherichia coli, and Candida albicans and are responsible for the activity of the crude extract. Actinomycin D (1) was also found to downregulate several glioma metabolic enzymes of glycolysis, glutaminolysis, and lipogenesis, suggesting that targeting multiple tumor metabolic regulators might be a new anti-glioma mechanism of actinomycin D. This is the first report of such a possible mechanism for the class of actinomycins. PMID:27727167

  12. [Effect of actinomycin D on the reproduction of the Machupo virus].

    PubMed

    Lukashevich, I S; Lemeshko, N N; Shkolina, T V

    1984-01-01

    The effect of inhibitors of mRNA synthesis (actinomycin D and alpha-amanitin) and DNA replication (mitomycin C and ethidium bromide) on Machupo virus reproduction was studied. Actinomycin D (1.0-4.0 micrograms/ml) and alpha-amanitin (10.0 micrograms/ml) added immediately after adsorption reduced the infectious virus titre by 2 lg or more. Actinomycin D inhibited virus reproduction not only at the early but also at the later stages of infection. Mitomycin C and ethidium bromide did not inhibit Machupo virus reproduction. The cells treated with actinomycin D at early and late stages of infection were found to contain immunoprecipitable virus-specific proteins 78, 64, and 37 KD described previously. The total amount of virus-specific proteins in the inhibitor-treated cells was reduced 3.7 and 2,6-fold after addition of actinomycin at 0 and 12 h postinfection, respectively, as compared with untreated cells. The mechanism of action of actinomycin D on the Machupo virus reproduction is discussed.

  13. [Assessment of Binding Properties of Actinomycin and Its Derivatives with DNA Molecule Using Molecular Dynamics Simulation Method].

    PubMed

    Volokh, O I; Bozdaganyan, M E; Shaitan, K V

    2015-01-01

    Molecular dynamics simulation method was used to assess an influence of actinomycins (antibiotics used in chemotherapy for treatment of some oncology diseases) on DNA fragment elasticity. Also the efficiency of binding of actinomycin to DNA fragment was estimated. Energetic contributions of different substitutions of hydroxyl and amino-group to the phenoxazine ring of actinomycin were studied to analyze dynamic behavior and stability of antibiotic-DNA fragment complexes. Young modulus values were calculated for structures: DNA/DNA-actinomycin/DNA-7-hydroxyactinomycin/DNA-7-aminoactinomycin. Free energy calculations were performed for the formation of actinomycin- and two actinomycin analogues-DNA fragment complexes. Our results suggest that the inserted substitutions stabilize the structure of a DNA fragment via the formation of additional hydrogen bonds.

  14. Differential in vitro inhibition of feline enteric coronavirus and feline infectious peritonitis virus by actinomycin D.

    PubMed

    Lewis, E L; Harbour, D A; Beringer, J E; Grinsted, J

    1992-12-01

    The growth of feline enteric coronavirus strain 79-1683 in whole feline embryo cells was inhibited by the presence of 1 microgram/ml of actinomycin D in the culture fluid. No virus-specific mRNAs could be detected in such cultures and yields of infectious virus were depressed by > 99%. By contrast, the antigenically related feline infectious peritonitis virus strain 79-1146 was unaffected by the presence of actinomycin D, indicating a fundamental difference between the two feline coronavirus strains in their requirements for host-encoded function(s).

  15. Effects of actinomycin D on brain RNA synthesis and discrimination learning in the goldfish (Carassius auratus).

    PubMed

    Ohi, S

    1977-08-01

    Intracranial injection of actinomycin D 2 microgram inhibited about 70% of the brain RNA synthesis from 3 hr to 4 days after injection in the goldfish. Under these conditions, fish were given 4-day-training of visual discrimination between a card with vertical stripes and one with horizontal stripes. Fish injected intracranially with actinomycin D showed deficits in between-day retention (long-term memory) but not interruption of within-day acquisition (short-term memory). It is suggested that brain RNA synthesis is necessary only for the formation of long-term memory but not short-term memory.

  16. Paradoxical Effect of Actinomycin D: Regulation of Synthesis of Wound RNase at Translation in Turnip Tissue.

    PubMed

    Sacher, J A; Morgan, E J; De Larosa, D

    1975-09-01

    Cutting of tissue sections induces RNase (EC 2.7.7.16) activity (phase I) in white turnip (Brassica rapa L. var. rapa) which peaks in 4 or 7 hours and then declines rapidly (phase II). The increase is inhibited by cycloheximide; also RNase from tissue bathed in 99.8% D(2)O during phase I underwent a large increase in buoyant density, indicating that the increased activity is due to de novo synthesis. Actinomycin D inhibited induction of RNase only if given within the initial 45 minutes after cutting. When it was applied after 45 minutes, it caused enhancement (super-induction) of RNase activity for over 24 hours. The half-time for degradation of RNase during phase I in the presence of cycloheximide and phase II in the presence and absence of cycloheximide is the same, indicating that the decline in RNase activity is due to cessation of synthesis. Also the rate of degradation of RNase remains the same during superinduction, thus indicating that actinomycin D superinduction is due to maintenance of synthesis of RNase rather than inhibition of its rate of degradation. Consistent with this is the fact that actinomycin D superinduction of RNase is inhibited by cycloheximide. The evidence is consistent with the hypothesis that messenger RNA for RNase is long-lived and the decline in RNase is due to transscription of a regulator gene coding for a specific repressor protein during phase I which inhibits RNase synthesis at the level of translation. Superinduction of RNase activity by actinomycin D is explicable in terms of (a) inhibition of synthesis of the mRNA coding for a repressor protein that inhibits translation of RNase-specific mRNA, or, (b) differential stability of mRNAs in presence of actinomycin D, and competition among mRNAs for factors rate-limiting to translation, thus favoring synthesis of proteins coded by long-lived messengers.

  17. [Effect of actinomycin D on salinity acclimation of Paramecium calkinsi (Ciliophora, Peniculia)].

    PubMed

    Khlebovich, V V; Kulangieva, L V; Degtiarev, A V

    2004-01-01

    Salinity acclimation of euryhaline ciliate Paramecium calkinsi evaluated by swimming velocity was over in 4-5 days. In two series of the main experiment, the acclimation was over in two and three days when actinomycin D (an inhibitor of DNA-dependent RNA polymerase) was added after various periods of the ciliate incubation at a changed salinity (0, 3, 6, and 24 h). The obtained data indicate that the inhibiting effect of actinomycin D on salinity acclimation of P. calkinsi is manifested only within the first day of the ciliate incubation in an altered environment; by the end of this period their swimming velocity was similar to the control one (acclimation in the absence of the inhibitor). Thus, expression of genes associated with salinity acclimation in paramecium largely completes within the first day, while the acclimation continues for at least 4-5 days. We propose that the acclimation-competent species possess a correspondingly rich genetic program.

  18. Extracellular ribonuclease formation in Bacillus subtilis and its stimulation by actinomycin D

    PubMed Central

    Coleman, G.; Elliott, W. H.

    1965-01-01

    1. Extracellular ribonuclease is produced linearly for at least 3hr. by washed post-logarithmic-phase cells of Bacillus subtilis suspended in a medium containing maltose (1%) and casein hydrolysate (0·5%). 2. Low concentrations of actinomycin D (less than 2μg./ml.) stimulate ribonuclease formation, the maximum effect being observed with a concentration of 1μg./ml. Concentrations greater than 2μg./ml. are inhibitory. There is no parallel stimulation of α-amylase formed under the same conditions, and [14C]uracil incorporation into a perchloric acid-insoluble form is inhibited. 3. The actinomycin D-induced stimulation is not due to the presence of an activator, nor is the inhibition due to the release of an inhibitor by the cells. The effect is on the amount of ribonuclease produced in the medium. 4. Extracellular ribonuclease formation is partially inhibited by anaerobiosis, 2,4-dinitrophenol, sodium azide and by chloramphenicol and puromycin. 5. High concentrations of antibiotic do not completely inhibit ribonuclease formation, but a basal amount of enzyme representing 20min. synthesis in an uninhibited system is always produced. This `antibiotic-insensitive' enzyme could possibly represent preformed enzyme `in the pipe-line' en route to secretion. 6. The stimulated appearance of ribonuclease in the presence of 1μg. of actinomycin D/ml. is shown to be dependent on enzyme synthesis. The mechanism of this effect is discussed. PMID:14342505

  19. The Circadian Rhythm in Photosynthesis in Acetabularia in the Presence of Actinomycin D, Puromycin, and Chloramphenicol

    PubMed Central

    Sweeney, Beatrice M.; Tuffli, Charles F.; Rubin, Richard H.

    1967-01-01

    Anucleate Acetabularia crenulata shows a circadian rhythm in photosynthesis. In this study, an oxygen electrode was employed to measure this photosynthetic rhythm in the presence and absence of the inhibitors, actinomycin D, chloramphenicol, and puromycin. High concentrations of the inhibitors were used: actinomycin D, 20–40 µg ml-1 puromycin, 30 and 100 µg ml-1; and chloramphenicol, 250 µg ml-1. The effectiveness of these inhibitors on protein synthesis was also measured under the same conditions used for the determination of rhythmicity. In spite of large effects of all three inhibitors on the incorporation of 14C leucine, no effect on the period or the phase of the photosynthetic rhythm was observed. The higher concentration of puromycin and chloramphenicol produced toxic effects which were expressed as a reduction in the amount of photosynthesis, but rhythmicity was still apparent. After 3 or 4 days' exposure to actinomycin, Acetabularia became resistant to its effect. Recovery was also observed in the ability to incorporate leucine. The implications of these results for theories of the basic oscillator responsible for circadian rhythmicity are discussed. PMID:11526851

  20. The circadian rhythm in photosynthesis in Acetabularia in the presence of actinomycin D, puromycin, and chloramphenicol.

    PubMed

    Sweeney, B M; Tuffli, C F; Rubin, R H

    1967-01-01

    Anucleate Acetabularia crenulata shows a circadian rhythm in photosynthesis. In this study, an oxygen electrode was employed to measure this photosynthetic rhythm in the presence and absence of the inhibitors, actinomycin D, chloramphenicol, and puromycin. High concentrations of the inhibitors were used: actinomycin D, 20-40 micrograms ml-1; puromycin, 30 and 100 micrograms ml-1; and chloramphenicol, 250 micrograms ml-1. The effectiveness of these inhibitors on protein synthesis was also measured under the same conditions used for the determination of rhythmicity. In spite of large effects of all three inhibitors on the incorporation of 14C leucine, no effect on the period or the phase of the photosynthetic rhythm was observed. The higher concentration of puromycin and chloramphenicol produced toxic effects which were expressed as a reduction in the amount of photosynthesis, but rhythmicity was still apparent. After 3 or 4 days' exposure to actinomycin, Acetabularia became resistant to its effect. Recovery was also observed in the ability to incorporate leucine. The implications of these results for theories of the basic oscillator responsible for circadian rhythmicity are discussed.

  1. Development of a physiologically based pharmacokinetic model of actinomycin D in children with cancer

    PubMed Central

    Walsh, Christopher; Bonner, Jennifer J.; Johnson, Trevor N.; Neuhoff, Sibylle; Ghazaly, Essam A.; Gribben, John G.; Boddy, Alan V.

    2016-01-01

    Aims Use of the anti‐tumour antibiotic actinomycin D is associated with development of hepatotoxicity, particularly in young children. A paucity of actinomycin D pharmacokinetic data make it challenging to develop a sound rationale for defining dosing regimens in younger patients. The study aim was to develop a physiologically based pharmacokinetic (PBPK) model using a combination of data from the literature and generated from experimental analyses. Methods Assays to determine actinomycin D Log P, blood:plasma partition ratio and ABCB1 kinetics were conducted. These data were combined with physiochemical properties sourced from the literature to generate a compound file for use within the modelling‐simulation software Simcyp (version 14 release 1). For simulation, information was taken from two datasets, one from 117 patients under the age of 21 and one from 20 patients aged 16–48. Results The final model incorporated clinical renal and biliary clearance data and an additional systemic clearance value. The mean AUC0‐26h of simulated subjects was within 1.25‐fold of the observed AUC0‐26h (84 ng h ml−1 simulated vs. 93 ng h ml−1 observed). For the younger age ranges, AUC predictions were within two‐fold of observed values, with simulated data from six of the eight age/dose ranges falling within 15% of observed data. Simulated values for actinomycin D AUC0‐26h and clearance in infants aged 0–12 months ranged from 104 to 115 ng h ml−1 and 3.5–3.8 l h−1, respectively. Conclusions The model has potential utility for prediction of actinomycin D exposure in younger patients and may help guide future dosing. However, additional independent data from neonates and infants is needed for further validation. Physiological differences between paediatric cancer patients and healthy children also need to be further characterized and incorporated into PBPK models. PMID:26727248

  2. Early estrogen-induced metabolic changes and their inhibition by actinomycin D and cycloheximide in human breast cancer cells: sup 31 P and sup 13 C NMR studies

    SciTech Connect

    Neeman, M.; Degani, H. )

    1989-07-01

    Metabolic changes following estrogen stimulation and the inhibition of these changes in the presence of actinomycin D and cycloheximide were monitored continuously in perfused human breast cancer T47D clone 11 cells with {sup 31}P and {sup 13}C NMR techniques. The experiments were performed by estrogen rescue of tamoxifen-treated cells. Immediately after perfusion with estrogen-containing medium, a continuous enhancement in the rates of glucose consumption, lactate production by glycolysis, and glutamate synthesis by the Krebs cycle occurred with a persistent 2-fold increase at 4 hr. Pretreatment with either actinomycin D or cycloheximide, at concentrations known to inhibit mRNA and protein synthesis, respectively, and simultaneous treatment with estrogen and each inhibitor prevented the estrogen-induced changes in glucose metabolism. This suggested that the observed estrogen stimulation required synthesis of mRNA and protein. These inhibitors also modulated several metabolic activities that were not related to estrogen stimulation. The observed changes in the in vivo kinetics of glucose metabolism may provide a means for the early detection of the response of human breast cancer cells to estrogen versus tamoxifen treatment.

  3. X-2 on Transportation Dolly

    NASA Technical Reports Server (NTRS)

    1952-01-01

    This 1952 photograph shows the X-2 #2 aircraft mounted on a special transportation dolly at Edwards Air Force Base, California. The dolly was steerable and was used for transporting the X-2 around and for towing it off the lakebed at Edwards Air Force Base after a landing. This was the number 2 airplane (46-675), which was lost on May 12, 1953, on a captive flight over Lake Ontario when the airplane exploded during a liquid-oxygen topoff test, killing the pilot, Jean Ziegler, and EB-50A crewman Frank Wolko. Almost no debris was recovered from Lake Ontario, so no cause for the explosion could be determined. Later, however, investigations of similar explosions in the X-1 #3, X-1A, and X-1D traced the problem to Ulmer leather gaskets, which exuded tricresyl phosphate. This substance caused detonations in the supercold atmosphere of the airplanes' liquid oxygen tanks. As the X-2 #2 also had these gaskets, they were probably the cause of the explosion in that aircraft as well. The X-2 was a swept-wing, rocket-powered aircraft designed to fly faster than Mach 3 (three times the speed of sound). It was built for the U.S. Air Force by the Bell Aircraft Company, Buffalo, New York. The X-2 was flown to investigate the problems of aerodynamic heating as well as stability and control effectiveness at high altitudes and high speeds (in excess of Mach 3). Bell aircraft built two X-2 aircraft. These were constructed of K-monel (a copper and nickel alloy) for the fuselage and stainless steel for the swept wings and control surfaces. The aircraft had ejectable nose capsules instead of ejection seats because the development of ejection seats had not reached maturity at the time the X-2 was conceived. The X-2 ejection canopy was successfully tested using a German V-2 rocket. The X-2 used a skid-type landing gear to make room for more fuel. The airplane was air launched from a modified Boeing B-50 Superfortress Bomber. X-2 Number 1 made its first unpowered glide flight on Aug. 5, 1954

  4. The effects of cortisoland actinomycin D injections on choloride cells and branchial N+---K+-ATPase in rainbow trout (Salmo gairdneri)

    USGS Publications Warehouse

    Eib, D.W.; Hossner, K.L.

    1985-01-01

    Injections of cortisol, actinomycin D, or combined administration of the hormone and the antiobiotic did not effect rainbow trout (Salmo gairdneri) branchial Na+K+-ATPase activity. Numbers of chloride cells also did not change following cortisol and actinomycin D treatment. These results are discussed in light of a similar report concerning Atlantic salmon (Salmo salar).

  5. Valentines Day X2 Flare

    NASA Video Gallery

    Active region 1158 let loose with an X2.2 flare at 0153 UT or 8:50 pm ET on February 15, 2011, the largest flare since Dec. 2006 and the biggest flare so far in Solar Cycle 24. This video was taken...

  6. [Effect of iron, actinomycin D and cycloheximide on the GTP-cyclohydrolase synthesis in flavinogenic yeasts].

    PubMed

    Logvinenko, E M; Shavlovskiĭ, G M; Zakal'skiĭ, A E; Zakhodylo, I V

    1982-01-01

    The effect of Fe on the GTP-cyclohydrolase activity of the yeasts Pichia guilliermondii ATCC 9058 and Torulopsis candida BKM 13 whose flavinogenesis is controlled by Fe was investigated. The GTP-cyclohydrolase activity of yeast cells grown in an iron-deficient medium was 40-50 times that of the cells grown in an iron-rich medium. In the latter case the incubation of cells with alpha, alpha'-dipyridyl or 8-oxyquinoline also increased the enzyme activity. Cycloheximide prevented the rise in the cyclohydrolase activity in both cases, thus suggesting the participation of Fe in the control of the enzyme synthesis. Actinomycin D inhibited the enzyme derepression induced by alpha, alpha1-dipyridyl or 8-oxyquinoline in the P. guilliermondii MS1-37 mutant possessing a high sensitivity to this antibiotic. It is assumed that Fe is involved in the control of GTP-cyclohydrolase synthesis in flavinogenic yeasts at the transcription level. PMID:7199939

  7. DETECTION OF DNA BY TRITIATED ACTINOMYCIN D ON ULTRATHIN FROZEN SECTIONS

    PubMed Central

    Bernier, Roch; Iglesias, Roberto; Simard, René

    1972-01-01

    Ultrathin frozen sections of fresh liver tissue were floated on actinomycin D-3H. Quantitative high resolution radioautography was performed to determine the value of the method for detection of DNA by electron microscopy. A complete series of control experiments involving various treatments of frozen sections with enzymes (pronase, DNase) and 0.1 N HCl were also carried out to determine the specificity of the labeling. The results indicate the value of the method for detection of DNA directly on ultrathin frozen sections. Short treatments with pronase followed by DNase reduce the labeling to zero, whereas removal of chromosomal proteins with HCl increases the amount of radioactivity in the nucleus considerably. The results are discussed in view of the future applications opened by ultracryotomy, since radioautographic detection of various macromolecules and cellular components by labeled compound with specific affinities will now be possible. PMID:4554990

  8. Detection of dengue virus from mosquito cell cultures inoculated with human serum in the presence of actinomycin D.

    PubMed

    Ramos, C; Villaseca, J M; García, H; Hernández, D G; Ramos-Castañeda, J; Imbert, J L

    1995-01-01

    We report the use of cultures of mosquito cells (TRA-284) to detect dengue virus in serum from cases of dengue fever in the state of Puebla, México. Using the conventional procedure 56 of 171 samples (32.7%) were positive. The negative sera (67.3%) were passaged 'blind' in mosquito cell cultures but no virus was detected. However, when these sera were incubated in the presence of actinomycin D (an inhibitor of deoxyribonucleic acid transcription) 20 of the 115 samples (17.4%) became positive. This procedure increased the virus detection rate from 32.7% to 44.4%. Serotypes 1 and 4 were identified for the first time in the state of Puebla, where the transmission of dengue virus is increasing. The addition of actinomycin D to mosquito cell cultures may improve the detection of dengue virus and could be a useful tool for virological surveillance in endemic countries.

  9. Actinomycin D binding mode reveals the basis for its potent HIV-1 and cancer activity

    NASA Astrophysics Data System (ADS)

    Paramanathan, Thayaparan; Vladescu, Ioana D.; McCauley, Micah J.; Rouzina, Ioulia; Williams, Mark C.

    2011-03-01

    Actinomycin D (ActD) is one of the most studied antibiotics, which has been used as an anti-cancer agent and also shown to inhibit HIV reverse transcription. Initial studies with ActD established that it intercalates double stranded DNA (dsDNA). However, recent studies have shown that ActD binds with even higher affinity to single stranded DNA (ssDNA). In our studies we use optical tweezers to stretch and hold single dsDNA molecule at constant force in the presence of varying ActD concentrations until the binding reaches equilibrium. The change in dsDNA length upon ActD binding measured as a function of time yields the rate of binding in addition to the equilibrium lengthening of DNA. The results suggest extremely slow kinetics, on the order of several minutes and 0.52 +/- 0.06 μ M binding affinity. Holding DNA at constant force while stretching and relaxing suggests that ActD binds to two single strands that are close to each other rather than to pure dsDNA or ssDNA. This suggests that biological activity of ActD that contributes towards the inhibition of cellular replication is due to its ability to bind at DNA bubbles during RNA transcription, thereby stalling the transcription process.

  10. Actin isoform synthesis by cultured cardiac myocytes: effects of actinomycin D and mithramycin

    SciTech Connect

    Lewis, W.; Gonzalez, B.

    1986-03-01

    Cultured neonatal rat myocardial cells (CMC) were incubated with the Actinomycin D (ACT) and mithramycin (MIT) in concentrations of 1 x 10/sup -8/M to 1 x 10/sup -5/M in medium containing 35..mu..Ci of /sup 35/S-methionine to determine incorporation into myocardial contractile proteins. After 24h, cells were harvested in buffer with Triton X-100, homogenized and subjected to centrifugation. Protein content of the centrifuged extracts was determined and equivalent amounts of protein were applied to 8-15% gradient sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS PAGE). Similar aliquots were subjected to isoelectric focusing and to gel electrophoresis in the second dimension. Electrophoretic gels were autoradiographed and were quantified densitometrically. A concentration-dependent effect of ACT and MIT on protein and on actin synthesis was found in cultured myocytes with decreased intensity of the radiolabeled actin band in CMC exposed to 1 x 10/sup -8/M to 1 x 10/sup -5/M ACT of 1 x 10/sup -7/M to 1 x 10/sup -5/M MIT. Autoradiography of gels showed focusing of actin isoforms but decreased intensity of iso-actin spots in extracts from CMC exposed to 1 x 10/sup -7/M ACT. ACT and MIT decreased CMC protein and synthesis by 20% at 1 x 10/sup -8/M respectively. The effect of MIT and ACT on CMC actin synthesis and synthesis of other proteins in heart cells is not as specific as the effect of anthracycline antineoplastics on cardiac myocyte proteins and actin.

  11. Organ culture of fetal rat intestine. Effects on brush border enzyme activities of the combined administration of dexamethasone and cycloheximide or actinomycin D.

    PubMed

    Simon-Assmann, P; Kédinger, M; Grenier, J F; Haffen, K

    1984-01-01

    Jejunum of 19-day fetal rats was explanted in organ culture for 48 h in the presence of dexamethasone (DX) and cycloheximide (CX) or actinomycin D (Act D). The concentrations of both inhibitors which provided maximal responses without any detrimental alteration of the tissue were determined. During the culture period, CX (0.5 microgram/ml) totally abolished the production of both DX-stimulated enzymes (sucrase, maltase, lactase) and DX-insensitive enzymes (aminopeptidase, alkaline phosphatase). On the contrary, Act D at 2 micrograms/ml exhibited differential levels of inhibition related to the enzyme considered: 100% for sucrase and aminopeptidase, 70% for maltase and 50% for lactase. By contrast, alkaline phosphatase was stimulated 100% by Act D. These data suggest that the mechanism by which DX induces sucrase and stimulates maltase activity takes place at the transcriptional level. They also indicate that the basic maturation of at least maltase and lactase activities depends upon the traduction of a preexisting pool of mRNAs. The superinduced alkaline phosphatase activity obtained with Act D supports the notion that an Act D-sensitive repressor may play a role in the maturation process of this enzyme.

  12. [The effects of actinomycin D on the brain RNA synthesis and on the passive avoidance latency in the goldfish (author's transl)].

    PubMed

    Ohi, S

    1975-10-01

    (a) Intracranial injection of actinomycin D (2 mug/10 mul/fish) inhibited about 70% of the goldfish brain RNA synthesis from 3 hours to 4 days later. (b) The goldfish injected actinomycin D intracranially was given the passive avoidance training. Intraday-acquisition (short-term memory) was not blocked but interday-retention (long-term memory) was markedly blocked. It might suggest that the brain RNA synthesis is not related to short-term memory but is necessary for long-term memory.

  13. Students Learn About SpaceX-2

    NASA Video Gallery

    From NASA's International Space Station Mission Control Center, Dorrie Tomayko, SpaceX-2 lead visiting vehicle officer, participates in a Digital Learning Network (DLN) event with students at Salt ...

  14. LMC X-2: Hunting the Z

    NASA Astrophysics Data System (ADS)

    Smale, A. P.; Kuulkers, E.

    2001-12-01

    We have performed three observations of LMC X-2 with RXTE in 1997 Dec, 2001 Feb, and most recently 2001 Aug-Sep, with further pointings scheduled for late 2001. Based on our results to date (see e.g. Smale & Kuulkers 2000, ApJ, 528, 702) we have developed the working hypothesis that LMC X-2 is a Z-source, spending most of its time in the Flaring Branch with occasional excursions onto the Normal Branch -- behavior reminiscent of the Z-source GX349+2. If confirmed, this would make LMC X-2 the eighth Z-source known and the first outside our Galaxy. We will present a summary of our LMC X-2 campaign, including light curves and color-color diagrams illustrating the two branches and the results of timing and spectral fitting analyses, and discuss our future strategy for resolving the nature of this bright low-mass X-ray binary.

  15. LMC X-2: Hunting the Z

    NASA Astrophysics Data System (ADS)

    Smale, Alan

    Data from an RXTE observation of LMC X-2 in 1997 Dec revealed that the shapes of the color-color and hardness-intensity diagrams, the presence of VLFN and HFN in the power spectra, and the high intrinsic Lx are more typical of a flaring Z-source than an atoll source (Smale and Kuulkers, 2000, ApJ, 528, 702). This would make LMC X-2 the 8th Z- source known, and the first detected beyond our Galaxy. A followup RXTE observation in 2001 Feb appears to show a combination of Flaring and Normal branches. We propose a Cycle 7 campaign to sample LMC X-2 for 20 weeks at 15 ksec/wk, to attempt to map out the (probable) Z, and further study the timing and spectral variability of the source.

  16. A 3 x 2 Achievement Goal Model

    ERIC Educational Resources Information Center

    Elliot, Andrew J.; Murayama, Kou; Pekrun, Reinhard

    2011-01-01

    In the present research, a 3 x 2 model of achievement goals is proposed and tested. The model is rooted in the definition and valence components of competence, and encompasses 6 goal constructs: task-approach, task-avoidance, self-approach, self-avoidance, other-approach, and other-avoidance. The results from 2 studies provided strong support for…

  17. The Actinomycin Biosynthetic Gene Cluster of Streptomyces chrysomallus: a Genetic Hall of Mirrors for Synthesis of a Molecule with Mirror Symmetry ▿

    PubMed Central

    Keller, Ullrich; Lang, Manuel; Crnovcic, Ivana; Pfennig, Frank; Schauwecker, Florian

    2010-01-01

    A gene cluster was identified which contains genes involved in the biosynthesis of actinomycin encompassing 50 kb of contiguous DNA on the chromosome of Streptomyces chrysomallus. It contains 28 genes with biosynthetic functions and is bordered on both sides by IS elements. Unprecedentedly, the cluster consists of two large inverted repeats of 11 and 13 genes, respectively, with four nonribosomal peptide synthetase genes in the middle. Nine genes in each repeat have counterparts in the other, in the same arrangement but in the opposite orientation, suggesting an inverse duplication of one of the arms during the evolution of the gene cluster. All of the genes appear to be organized into operons, each corresponding to a functional section of actinomycin biosynthesis, such as peptide assembly, regulation, resistance, and biosynthesis of the precursor of the actinomycin chromophore 4-methyl-3-hydroxyanthranilic acid (4-MHA). For 4-MHA synthesis, functional analysis revealed genes that encode pathway-specific isoforms of tryptophan dioxygenase, kynurenine formamidase, and hydroxykynureninase, which are distinct from the corresponding enzyme activities of cellular tryptophan catabolism in their regulation and in part in their substrate specificity. Phylogenetic analysis indicates that the pathway-specific tryptophan metabolism in Streptomyces most probably evolved divergently from the normal pathway of tryptophan catabolism to provide an extra or independent supply of building blocks for the synthesis of tryptophan-derived secondary metabolites. PMID:20304989

  18. X1X1X2X2/X1X2Y sex chromosome systems in the Neotropical Gymnotiformes electric fish of the genus Brachyhypopomus.

    PubMed

    Cardoso, Adauto Lima; Pieczarka, Julio Cesar; Nagamachi, Cleusa Yoshiko

    2015-05-01

    Several types of sex chromosome systems have been recorded among Gymnotiformes, including male and female heterogamety, simple and multiple sex chromosomes, and different mechanisms of origin and evolution. The X1X1X2X2/X1X2Y systems identified in three species of this order are considered homoplasic for the group. In the genus Brachyhypopomus, only B. gauderio presented this type of system. Herein we describe the karyotypes of Brachyhypopomus pinnicaudatus and B. n. sp. FLAV, which have an X1X1X2X2/X1X2Y sex chromosome system that evolved via fusion between an autosome and the Y chromosome. The morphology of the chromosomes and the meiotic pairing suggest that the sex chromosomes of B. gauderio and B. pinnicaudatus have a common origin, whereas in B . n. sp. FLAV the sex chromosome system evolved independently. However, we cannot discard the possibility of common origin followed by distinct processes of differentiation. The identification of two new karyotypes with an X1X1X2X2/X1X2Y sex chromosome system in Gymnotiformes makes it the most common among the karyotyped species of the group. Comparisons of these karyotypes and the evolutionary history of the taxa indicate independent origins for their sex chromosomes systems. The recurrent emergence of the X1X1X2X2/X1X2Y system may represent sex chromosomes turnover events in Gymnotiformes. PMID:26273225

  19. Combination of TRAIL and actinomycin D liposomes enhances antitumor effect in non-small cell lung cancer.

    PubMed

    Guo, Liangran; Fan, Li; Ren, Jinfeng; Pang, Zhiqing; Ren, Yulong; Li, Jingwei; Wen, Ziyi; Qian, Yong; Zhang, Lin; Ma, Hang; Jiang, Xinguo

    2012-01-01

    The intractability of non-small cell lung cancer (NSCLC) to multimodality treatments plays a large part in its extremely poor prognosis. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising cytokine for selective induction of apoptosis in cancer cells; however, many NSCLC cell lines are resistant to TRAIL-induced apoptosis. The therapeutic effect can be restored by treatments combining TRAIL with chemotherapeutic agents. Actinomycin D (ActD) can sensitize NSCLC cells to TRAIL-induced apoptosis by upregulation of death receptor 4 (DR4) or 5 (DR5). However, the use of ActD has significant drawbacks due to the side effects that result from its nonspecific biodistribution in vivo. In addition, the short half-life of TRAIL in serum also limits the antitumor effect of treatments combining TRAIL and ActD. In this study, we designed a combination treatment of long-circulating TRAIL liposomes and ActD liposomes with the aim of resolving these problems. The combination of TRAIL liposomes and ActD liposomes had a synergistic cytotoxic effect against A-549 cells. The mechanism behind this combination treatment includes both increased expression of DR5 and caspase activation. Moreover, systemic administration of the combination of TRAIL liposomes and ActD liposomes suppressed both tumor formation and growth of established subcutaneous NSCLC xenografts in nude mice, inducing apoptosis without causing significant general toxicity. These results provide preclinical proof-of-principle for a novel therapeutic strategy in which TRAIL liposomes are safely combined with ActD liposomes.

  20. Actinomycin D and nutlin-3a synergistically promote phosphorylation of p53 on serine 46 in cancer cell lines of different origin.

    PubMed

    Zajkowicz, Artur; Gdowicz-Kłosok, Agnieszka; Krześniak, Małgorzata; Ścieglińska, Dorota; Rusin, Marek

    2015-09-01

    The p53 tumor suppressor protein is a transcription factor activated by phosphorylation of its N-terminus. MDM2, encoded by a p53-activated gene, acts as a negative-feedback regulator of p53 by promoting p53 degradation. Moreover, MDM2 inhibits p53 by binding to and concealing its N-terminal transcription-activating domain. p53 can be activated by nutlin-3a, a molecule designed to bind MDM2 and prevent its interaction with p53. Actinomycin D promotes phosphorylation and accumulation of p53 via a mechanism that involves high expression of MDM2. We hypothesized that co-treatment of cells with actinomycin D and nutlin-3a would lead to synergistic activation of p53 by stimulating kinases and preventing accumulated MDM2 from binding to p53. Indeed, co-treatment of various cell lines with actinomycin D and nutlin-3a resulted in a synergistic increase of p53 phosphorylation on serine 46. We focused on this residue because it is a marker of the highest level of p53 activation. Co-treatment was associated with conspicuous decrease in a marker of mTOR activity in NCI-H28 cells and very strong activation of p53 targets, including CDKN1A and PML, in A549 cells. Other p53 target genes (SESN1, SESN2, TIGAR, DRAM1) were also efficiently upregulated; however, a marker of apoptosis (active caspase-3) appeared only in some cancer cell lines (e.g., A375 and other cell lines derived from melanoma) indicating that phosphorylation of p53 on serine 46 is not straightforwardly associated with induction of apoptosis. Moreover, our data suggest that melanoma may be a suitable target for drug combination used in this study.

  1. Severe Hepatic Sinusoidal Obstruction Syndrome in a Child Receiving Vincristine, Actinomycin-D, and Cyclophosphamide for Rhabdomyosarcoma: Successful Treatment with Defibrotide

    PubMed Central

    Choi, Aery; Kang, Young Kyung; Lim, Sewon; Kim, Dong Ho; Lim, Jung Sub; Lee, Jun Ah

    2016-01-01

    Hepatic sinusoidal obstruction syndrome (SOS) is a life-threatening syndrome that generally occurs as a complication after hematopoietic stem cell transplantation or, less commonly, after conventional chemotherapy. Regarding SOS in rhabdomyosarcoma patients who received conventional chemotherapy, the doses of chemotherapeutic agents are associated with the development of SOS. Several cases of SOS in rhabdomyosarcoma patients after receiving chemotherapy with escalated doses of cyclophosphamide have been reported. Here, we report on a 9-year-old female with rhabdomyosarcoma who developed severe SOS after receiving chemotherapy consisting of vincristine, actinomycin-D, and a moderate dose of cyclophosphamide. She was treated successfully with defibrotide without sequelae to the liver. PMID:27034141

  2. Experimental suppression of tolerance to ozone and of cross-tolerance (NO/sub 2/-O/sub 3/) in rats by actinomycin D and colchicine

    SciTech Connect

    Nambu, Z.; Yokoyama, E.

    1982-10-01

    Rats were initially exposed to 2 ppm ozone or 16-20 ppm NO/sub 2/ for 3 hr in order to induce a certain tolerance to ozone during 3 days after the initial exposure. After the initial exposure, they were intraperitoneally administered actinomycin D or colchicine at a scheduled interval. Twenty-four hours after the administration, the induction of tolerance was assayed by the response of lung weight to challenge exposure to 5.6 ppm ozone for 3 hr. Either actinomycin D or colchicine administered immediately after the initial exposure suppressed the induction of tolerance (O/sub 3/-O/sub 3/) and of cross-tolerance (NO/sub 2/-O/sub 3/), while the tolerance was not suppressed by the inhibitors administered 12 to 24 hr following the initial exposure. Normal tolerance to ozone was induced 12 to 24 hr after the initial exposure. It was thus shown that the induction of tolerance could not be suppressed by the inhibitors administered after the lungs became fully tolerant; we tentatively interpret these results to suggest that no tolerance is induced without pulmonary cell proliferation stimulated by the initial exposure.

  3. Comments on the ring-opening polymerization of morpholine-2,5-dione derivatives by various metal catalysts and characterization of the products formed in the reactions involving R2SnX2, where X = OPr(i) and NMe2 and R = Bu(n), Ph and p-Me2NC6H4.

    PubMed

    Chisholm, M H; Galucci, J; Krempner, C; Wiggenhorn, C

    2006-02-14

    (3S,6S)-3-Isopropyl-6-methyl-morpholine-2,5-dione (1), and (3S,6S)-3,6-dimethyl-morpholine-2,5-dione (2), do not enter into ring-opening polymerization reactions with metal catalyst precursors commonly employed for lactides, and with Sn(II) octanoate, only low molecular weight oligomers are obtained. Reactions with R2SnX2 compounds, where R = Ph, Bu(n) and p-Me2NC6H4 and X = OPr(i) or NMe2, reveal that ring-opening of the morpholine-2,5-diones does occur, but that polymerization is terminated by the formation of kinetically-inert products such as {Ph2Sn[mu,eta(3)-OCH(Me)CONCH(Pr(i))COOPr(i)]}2 (3), and {[Bu(n))2Sn[mu,eta(3)-OCH(Me)CONCH(Me)CONMe2]}2 (4), with elimination of HX. Ph3SnOPr(i) is seen to react reversibly with morpholine-2,5-diones in toluene-d8 by 1H NMR spectroscopy while (Bu(n))3SnNMe2 reacts by ring opening to give (Bu(n))3SnOCH(Me)C(O)NHCHMeC(O)NMe2. The new organotin compounds have been characterized by 1H, 13C{1H} and 118Sn NMR spectroscopy and compounds 1, 2, 3 and 4 by single crystal X-ray crystallography.

  4. Comments on the ring-opening polymerization of morpholine-2,5-dione derivatives by various metal catalysts and characterization of the products formed in the reactions involving R2SnX2, where X = OPr(i) and NMe2 and R = Bu(n), Ph and p-Me2NC6H4.

    PubMed

    Chisholm, M H; Galucci, J; Krempner, C; Wiggenhorn, C

    2006-02-14

    (3S,6S)-3-Isopropyl-6-methyl-morpholine-2,5-dione (1), and (3S,6S)-3,6-dimethyl-morpholine-2,5-dione (2), do not enter into ring-opening polymerization reactions with metal catalyst precursors commonly employed for lactides, and with Sn(II) octanoate, only low molecular weight oligomers are obtained. Reactions with R2SnX2 compounds, where R = Ph, Bu(n) and p-Me2NC6H4 and X = OPr(i) or NMe2, reveal that ring-opening of the morpholine-2,5-diones does occur, but that polymerization is terminated by the formation of kinetically-inert products such as {Ph2Sn[mu,eta(3)-OCH(Me)CONCH(Pr(i))COOPr(i)]}2 (3), and {[Bu(n))2Sn[mu,eta(3)-OCH(Me)CONCH(Me)CONMe2]}2 (4), with elimination of HX. Ph3SnOPr(i) is seen to react reversibly with morpholine-2,5-diones in toluene-d8 by 1H NMR spectroscopy while (Bu(n))3SnNMe2 reacts by ring opening to give (Bu(n))3SnOCH(Me)C(O)NHCHMeC(O)NMe2. The new organotin compounds have been characterized by 1H, 13C{1H} and 118Sn NMR spectroscopy and compounds 1, 2, 3 and 4 by single crystal X-ray crystallography. PMID:16437180

  5. The structural basis of actinomycin D-binding induces nucleotide flipping out, a sharp bend and a left-handed twist in CGG triplet repeats.

    PubMed

    Lo, Yu-Sheng; Tseng, Wen-Hsuan; Chuang, Chien-Ying; Hou, Ming-Hon

    2013-04-01

    The potent anticancer drug actinomycin D (ActD) functions by intercalating into DNA at GpC sites, thereby interrupting essential biological processes including replication and transcription. Certain neurological diseases are correlated with the expansion of (CGG)n trinucleotide sequences, which contain many contiguous GpC sites separated by a single G:G mispair. To characterize the binding of ActD to CGG triplet repeat sequences, the structural basis for the strong binding of ActD to neighbouring GpC sites flanking a G:G mismatch has been determined based on the crystal structure of ActD bound to ATGCGGCAT, which contains a CGG triplet sequence. The binding of ActD molecules to GCGGC causes many unexpected conformational changes including nucleotide flipping out, a sharp bend and a left-handed twist in the DNA helix via a two site-binding model. Heat denaturation, circular dichroism and surface plasmon resonance analyses showed that adjacent GpC sequences flanking a G:G mismatch are preferred ActD-binding sites. In addition, ActD was shown to bind the hairpin conformation of (CGG)16 in a pairwise combination and with greater stability than that of other DNA intercalators. Our results provide evidence of a possible biological consequence of ActD binding to CGG triplet repeat sequences.

  6. LMC X-2: the First Extragalactic Z-Source

    NASA Astrophysics Data System (ADS)

    Smale, Alan

    Data from a 100ks RXTE observation of LMC X-2 in 1997 Dec reveal that the shapes of the color-color and hardness-intensity diagrams, the presence of VLFN and HFN in the power spectra, and the high intrinsic L_x are more typical of a flaring Z-source than an atoll source (Smale and Kuulkers, 2000, ApJ, 528, 702). This would make LMC X-2 the 8th Z- source known, and the first detected beyond our Galaxy. We also found a strong 8.16-hr modulation which appears to confirm a candidate P_orb from optical photometry, though we cannot rule out a chance alignment of flares. One follow-up pointing is planned for Cycle 5; we propose further observations in 2001 to study the time variability of LMC X-2, flesh out its probable Z, and confirm/reject the 8-hr periodicity.

  7. LMC X-2: the First Extragalactic Z-Source

    NASA Astrophysics Data System (ADS)

    Smale, Alan

    Using data from a 100ks RXTE observation of LMC X-2 in 1997 Dec, we found that the shapes of the color-color and hardness-intensity diagrams, the presence of VLFN and HFN in the power spectra, and the high intrinsic L_x are more typical of a Z-source in its flaring branch than of an atoll source (Smale and Kuulkers, 1999). This would make LMC X-2 the 8th Z-source known, and the first detected beyond our Galaxy. We also detected a strong 8.16-hr modulation which appears to confirm a candidate orbital period from optical photometry, though we cannot rule out a chance alignment of intrinsic flares. We propose a set of follow- up observations to (a) further study the high time variability of LMC X-2 and try to flesh out the branches of the Z, and (b) confirm/reject the 8-hr periodicity.

  8. X-2 on lakebed after landing on skids

    NASA Technical Reports Server (NTRS)

    1952-01-01

    This 1952 photograph shows the X-2 #2 (46-675) with a collapsed nose landing gear, after landing on the first glide flight at Edwards Air Force Base. The aircraft pitched at landing, slid along its main skid, and contacted the ground with the right wingtip bumper skid, causing it to break off. The nose wheel had collapsed upon contacting the ground. In the photo, Bell test pilot Jean Ziegler is still in the cockpit as ground crewmen stand by the aircraft. The X-2 #2 was subsequently destroyed in an explosion during captive flight on May 12, 1953, killing Ziegler and EB-50A crewmember Frank Wolko. The X-2 was a swept-wing, rocket-powered aircraft designed to fly faster than Mach 3 (three times the speed of sound). It was built for the U.S. Air Force by the Bell Aircraft Company, Buffalo, New York. The X-2 was flown to investigate the problems of aerodynamic heating as well as stability and control effectiveness at high altitudes and high speeds (in excess of Mach 3). Bell aircraft built two X-2 aircraft. These were constructed of K-monel (a copper and nickel alloy) for the fuselage and stainless steel for the swept wings and control surfaces. The aircraft had ejectable nose capsules instead of ejection seats because the development of ejection seats had not reached maturity at the time the X-2 was conceived. The X-2 ejection canopy was successfully tested using a German V-2 rocket. The X-2 used a skid-type landing gear to make room for more fuel. The airplane was air launched from a modified Boeing B-50 Superfortress Bomber. X-2 Number 1 made its first unpowered glide flight on Aug. 5, 1954, and made a total of 17 (4 glide and 13 powered) flights before it was lost Sept. 27, 1956. The pilot on Flight 17, Capt. Milburn Apt, had flown the aircraft to a record speed of Mach 3.2 (2,094 mph), thus becoming the first person to exceed Mach 3. During that last flight, inertial coupling occurred and the pilot was killed. The aircraft suffered little damage in the crash

  9. SpaceX 2: Liftoff of Falcon 9

    NASA Video Gallery

    SpaceX's Falcon 9 rocket and Dragon spacecraft launch on time at 10:10 a.m. EST from Launch Complex 40 at Cape Canaveral Air Force Station in Florida. The goal of the SpaceX 2 mission is to resuppl...

  10. Credit WCT. Original 2'" x 2'" color negative is housed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit WCT. Original 2-'" x 2-'" color negative is housed in the JPL Photography Laboratory, Pasadena, California. View shows small autoclave demonstrated by JPL staff member Milton Clay (JPL negative no. JPL-10286AC, 27 January 1989). - Jet Propulsion Laboratory Edwards Facility, Liner Laboratory, Edwards Air Force Base, Boron, Kern County, CA

  11. The Complete Z-diagram of LMC X-2

    NASA Technical Reports Server (NTRS)

    White, Nicholas E. (Technical Monitor); Smale, A. P.; Homan, J.; Kuulkers, E.

    2003-01-01

    We present results from four Rossi X-ray Timing Explorer (RXTE) observations of the bright low mass X-ray binary LMC X-2. During these observations, which span a year and include over 160 hrs of data, the source exhibits clear evolution through three branches on its hardness-intensity and color-color diagrams, consistent with the flaring, normal, and horizontal branches (FB, NB, HB) of a Z-source, and remarkably similar to Z-tracks derived for GX 17+2, Sco X-1 and GX 349+2. LMC X-2 was observed in the FB, NB, and HB for roughly 30%, 40%, and 30% respectively of the total time covered. The source traces out the full extent of the Z in approximately 1 day, and the Z-track shows evidence for secular shifts on a timescale in excess of a few days. Although the count rate of LMC X-2 is low compared with the other known 2-sources due to its greater distance, the power density spectra selected by branch show very-low-frequency noise characteristics at least consistent with those from other Z-sources. We thus confirm the identification of LMC X-2 as a Z-source, the first identified outside our Galaxy.

  12. Credit WCT. Original 2'" x 2%" color negative is housed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit WCT. Original 2-'" x 2-%" color negative is housed in the JPL Photography Laboratory, Pasadena, California. This view shows the propellant cutter as it was originally installed (JPL negative no. 381-2274A, 29 June 1962) - Jet Propulsion Laboratory Edwards Facility, Preparation Building, Edwards Air Force Base, Boron, Kern County, CA

  13. LMC X--2: The First Extragalactic Z-Source?

    NASA Astrophysics Data System (ADS)

    Smale, Alan P.; Kuulkers, Erik

    1999-04-01

    We present RXTE observations of LMC X--2 obtained during a five-day interval in 1997 December, during which the source was radiating at a mean intensity ~ 1.2LEdd and strongly variable on timescales of seconds to hours. The shapes of the X-ray color-color and hardness-intensity diagrams during the observations, the presence of VLFN and possible HFN in the power spectra, and the high intrinsic X-ray luminosity of LMC X--2 (which historically spans 0.4--2.0LEdd for reasonable estimates of the neutron star mass) are more characteristic of a Z-source in its flaring branch than of an atoll-source. On this basis, we provisionally reclassify LMC X--2 as a Z-source, the eighth such source known and the first to be detected beyond our Galaxy. Using periodogram and Fourier analysis of the X-ray lightcurve we detect an apparently-significant X-ray modulation with a period of 8.160+/-0.011 hrs and a semi-amplitude increasing from 14% in the 1.8--4.0 keV range to 40% at 8.7--19.7 keV. This X-ray modulation appears to confirm a candidate orbital periodicity determined from optical photometry ten years prior to our campaign, but we cannot rule out a chance alignment of intrinsic X-ray flares. Current RXTE ASM light curves, and archival EXOSAT observations, show no sign of such a pronounced periodicity. The X-ray spectrum of LMC X--2 can be well fit using variations of simple Comptonization models. Fits to intensity( =~ phase)-resolved spectra show strong correlations between the power law slope (in one parameterization) or the depth to optical scattering (in another) and intensity. We discuss the implications for the inclination, geometry, and emitting regions of the LMC X--2 system.

  14. Low-Dose Actinomycin-D Induces Redistribution of Wild-Type and Mutated Nucleophosmin Followed by Cell Death in Leukemic Cells.

    PubMed

    Brodská, Barbora; Holoubek, Aleš; Otevřelová, Petra; Kuželová, Kateřina

    2016-06-01

    Specific mutations involving C-terminal part of the nucleolar protein nucleophosmin (NPM) are associated with better outcome of acute myeloid leukemia (AML) therapy, possibly due to aberrant cytoplasmic NPM localization facilitating induction of anti-NPM immune response. Actinomycin D (actD) is known to induce nucleolar stress leading to redistribution of many nucleolar proteins, including NPM. We analyzed the distribution of both wild-type and mutated NPM (NPMmut) in human cell lines, before and after low-dose actD treatment, in living cells expressing exogenous fluorescently labeled proteins as well as using immunofluorescence staining of endogenous proteins in fixed cells. The wild-type NPM form is prevalently nucleolar in intact cells and relocalizes mainly to the nucleoplasm following actD addition. The mutated NPM form is found both in the nucleoli and in the cytoplasm of untreated cells. ActD treatment leads to a marked increase in NPMmut amount in the nucleoplasm while a mild decrease is observed in the cytoplasm. Cell death was induced by low-dose actD in all the studied leukemic cell lines with different p53 and NPM status. In cells expressing the tumor suppresor p53 (CML-T1, OCI-AML3), cell cycle arrest in G1/G0 phase was followed by p53-dependent apoptosis while in p53-null HL60 cells, transient G2/M-phase arrest was followed by cell necrosis. We conclude that although actD does not increase NPM concentration in the cytoplasm, it could improve the effect of standard chemotherapy in leukemias through more general mechanisms. PMID:26505272

  15. Tools for analyzing intersecting tracks: The x2sys package

    NASA Astrophysics Data System (ADS)

    Wessel, Paul

    2010-03-01

    I present a new set of tools for detection of intersections among tracks in 2-D Cartesian or geographic coordinates. These tools allow for evaluation of crossover errors at intersections, analysis of such crossover errors to determine appropriate linear models of systematic corrections for each track, and application of these corrections and further adjustments to data that completely eliminates crossover discrepancies from final 2-D data compilations. Unlike my older x_system tools, the new x2sys tools implement modern algorithms for detecting track intersections and are capable of reading a wide range of data file formats, including data files following the netCDF COARDS convention. The x2sys package contains several programs that address the various tasks needed to undertake a comprehensive crossover analysis and is distributed as a supplement to the Generic Mapping Tools, making them available for all computer platforms and architectures.

  16. Cygnus X-2 in a radio quiet state

    NASA Astrophysics Data System (ADS)

    Rushton, A.; Bach, U.; Spencer, R.; Kadler, M.; Church, M.; Balucinska-Church, M.; Wilms, J.; Hanke, M.; Zola, S.; Schulz, N.

    2009-05-01

    The neutron star X-ray binary Cygnus X-2 was observed using the e- EVN (European VLBI Network) on May 12/13th 2009 between 23:00-13:00 UT at 5 GHz. The radio telescopes participating with the e-EVN at 5 GHz were Effelsberg, Medicina, Onsala 25m, Torun, Sheshan, Yebes, Jodrell Bank MKII, Cambridge and Knockin. A maximum data rate of 1024 Mbps were achieved from four telescopes (Effelsberg, Onsala, Torun and Jodrell Bank MKII).

  17. Fatigue crack propagation in carburized X-2M steel

    NASA Astrophysics Data System (ADS)

    Averbach, B. L.; Lou, Bingzhe; Pearson, P. K.; Fairchild, R. E.; Bamberger, E. N.

    1985-07-01

    The growth rates of fatigue cracks propagating through the case and into the core have been studied for carburized X-2M steel (0.14 C, 4.91 Cr, 1.31 Mo, 1.34 W, 0.42 V). Fatigue cracks were propagated at constant stress intensities, ΔK, and also at a constant cyclic peak load, and the crack growth rates were observed to pass through a minimum value as the crack traversed the carburized case. The reduction in the crack propagation rates is ascribed to the compressive stresses which were developed in the case, and a pinched clothespin model is used to make an approximate calculation of the effects of internal stress on the crack propagation rates. We define an effective stress intensity, Ke = Ka + Ki, where Ka is the applied stress intensity, Ki = σid{i/1/2}, σi is the internal stress, and di is a characteristic distance associated with the depth of the internal stress field. In our work, a value of di = 11 mm (0.43 inch) fits the data quite well. A good combination of resistance to fatigue crack propagation in the case and fracture toughness in the core can be achieved in carburized X-2M steel, suggesting that this material will be useful in heavy duty gears and in aircraft gas turbine mainshaft bearings operating under high hoop stresses.

  18. Exosat observations of Cygnus X-2 continuum and line spectrum

    SciTech Connect

    Chiappetti, L.; Treves, A.; Ciapi, A.L.; Branduardi-Raymont, G.; Ercan, E.N. Milano Universita, Milan London Univ. College, Dorking Univ. of the Bosphorus, Istanbul )

    1990-10-01

    An analysis of five Exosat observations of Cyg X-2, taken around a full binary orbit is presented. The data were obtained using all instrumentation (1000 lines/mm Transmission Grating Spectrometer, Channel Multiplier Array + filters, Medium-Energy experiment, and Gas Scintillation Proportional Counter) simultaneously, and span the full energy range 0.5-20 keV. No clear evidence was found for a correlation of any of the source characteristics with orbital phase. During two of the observations, significant iron K emission at 6.7 keV was detected, the relative strength of which seems to correlate with total X-ray intensity during two sharp intensity dips. The previous detection of discrete emission features in the 12-19 A band with the Einstein grating is confirmed. 29 refs.

  19. Spectral analysis of SMC X-2 during its 2015 outburst

    NASA Astrophysics Data System (ADS)

    La Palombara, N.; Sidoli, L.; Pintore, F.; Esposito, P.; Mereghetti, S.; Tiengo, A.

    2016-05-01

    We report on the results of XMM-Newton and Swift observations of SMC X-2 during its last outburst in 2015 October, the first one since 2000. The source reached a very high luminosity (L ˜ 1038 erg s-1), which allowed us to perform a detailed analysis of its timing and spectral properties. We obtained a pulse period Pspin = 2.372267(5) s and a characterization of the pulse profile also at low energies. The main spectral component is a hard (Γ ≃ 0) power-law model with an exponential cut-off, but at low energies we detected also a soft (with kT ≃ 0.15 keV) thermal component. Several emission lines are present in the spectrum. Their identification with the transition lines of highly ionized N, O, Ne, Si, and Fe suggests the presence of photoionized matter around the accreting source.

  20. Precision Ephemerides for Gravitational Wave Searches. II. Cyg X-2

    NASA Astrophysics Data System (ADS)

    Premachandra, Sammanani S.; Galloway, Duncan K.; Casares, Jorge; Steeghs, Danny T.; Marsh, Thomas R.

    2016-06-01

    Accreting neutron stars in low-mass X-ray binaries are candidate high-frequency persistent gravitational wave sources. These may be detectable with next-generation interferometers such as Advanced LIGO/VIRGO within this decade. However, the search sensitivity is expected to be limited principally by the uncertainty in the binary system parameters. We combine new optical spectroscopy of Cyg X-2 obtained with the Liverpool Telescope with available historical radial velocity data, which gives us improved orbital parameter uncertainties based on a 44 year baseline. We obtained an improvement of a factor of 2.6 in the orbital period precision and a factor of 2 in the epoch of inferior conjunction T 0. The updated orbital parameters imply a mass function of 0.65 ± 0.01 M ⊙, leading to a primary mass (M 1) of 1.67 ± 0.22 M ⊙ (for i = 62.{}^\\circ 5+/- 4^\\circ ). In addition, we estimate the likely orbital parameter precision through to the expected Advanced LIGO and VIRGO detector observing period and quantify the corresponding improvement in sensitivity via the required number of templates.

  1. Comparison of ANOVA, McSweeney, Bradley, Harwell-Serlin, and Blair-Sawilowsky Tests in the Balanced 2x2x2 Layout.

    ERIC Educational Resources Information Center

    Kelley, D. Lynn; And Others

    The Type I error and power properties of the 2x2x2 analysis of variance (ANOVA) and tests developed by McSweeney (1967), Bradley (1979), Harwell-Serlin (1989; Harwell, 1991), and Blair-Sawilowsky (1990) were compared using Monte Carlo methods. The ANOVA was superior under the Gaussian and uniform distributions. The Blair-Sawilowsky test was…

  2. Extended analysis of the B2Σ+-X2Σ+ and A2Π-X2Σ+ systems of ZrN

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Soumen; Mukund, Sheo; Yarlagadda, Suresh; Nakhate, S. G.

    2014-11-01

    Rotationally resolved spectra of (1,0), (1,1), (2,0), (2,1) and (2,3) bands of B2Σ+-X2Σ+ and (3,3) band of A2Π-X2Σ+ systems have been measured in a laser-induced fluorescence spectra of jet cooled ZrN molecule. Rotational analysis have been extended to include the levels ν=3 of X2Σ+, ν=1,2 of B2Σ+ and ν=3 of A2Π states. The vibrational constants of the X2Σ+ state have been determined. Perturbations were observed in all the rotational branches of the B-X system and A2Π1/2f-X2Σ+ subband.

  3. [Investigation on spectrum of B 2sigma(+)-X 2sigma+ and C 2pi(r)-X 2sigma+ bands of AlO radical in shock tube].

    PubMed

    Peng, Zhi-Min; Yang, Qian-Suo; Liu, Chun; Zhu, Nai-Yi; Jiang, Zong-Lin

    2010-04-01

    There are some impurities such as aluminum dioxide adhering on the shock tube wall due to the ablating and heating of the aluminum diaphragm by high temperature gas. Under high temperature, the collision of AlO radicals with the gaseous molecules leads to transition of the electronic states and production of strong radiation, which disturb the analysis of radiation spectrum of heated gases in shock tube. In the authors' experiments, the air in the test section with adhering aluminum dioxide was heated to some 4 000-7 000 K, the spectrum of AlO radical was obvious in the range of 460-530 nm, which corresponds to B 2sigma(+)-X 2sigma+ (T00 = 20 689 cm(-1) band. There were several band heads for this band, the interval of neighbor heads was some 2 nm, and all the band heads were with the shortest wavelength. The characteristics of B 2sigma(+)-X 2sigma+ band were explored in experiment and by theory. In addition, the spectrum of C 2pi(r)-X 2sigma+ (T00 = 33 047 cm(-1)) band was also investigated. The corresponding strength was lower than that of B 2sigma(+) -X 2sigma+ band, and the wavelength range of this band was some 270-335 nm where the radiation of A 2sigma(+) -X 2pi (T00 = 32 682 cm(-1)) band of OH radical also existed. This occurrence of the two bands in the same wavelength range is disadvantageous for the spectrum analysis.

  4. Photoelectron spectroscopy of GaX2-, Ga2X-, Ga2X2-, and Ga2X3-(X=P,As)

    NASA Astrophysics Data System (ADS)

    Taylor, Travis R.; Gómez, Harry; Asmis, Knut R.; Neumark, Daniel M.

    2001-09-01

    Anion photoelectron spectra taken at various photodetachment wavelengths have been obtained for GaX2-, Ga2X-, Ga2X2-, and Ga2X3- (X=P,As). The incorporation of a liquid nitrogen cooled channel in the ion source resulted in substantial vibrational cooling of the cluster anions, resulting in resolved vibrational progressions in the photoelectron spectra of all species except Ga2X2-. Electron affinities, electronic term values, and vibrational frequencies are reported and compared to electronic structure calculations. In addition, similarities and differences between the phosphorus and arsenic-containing isovalent species are discussed.

  5. Isotope effects on the photodesorption processes of X2O (X = H,D) and HOD ice.

    PubMed

    Koning, J; Kroes, G J; Arasa, C

    2013-03-14

    To investigate the isotope effects on the photodesorption processes of X2O (X = H,D) ice, molecular dynamics calculations have been performed on the ultraviolet photodissociation of an H2O or a D2O molecule in an H2O or a D2O amorphous ice surface, and on HOD photodissociation in an H2O amorphous ice surface, where the photodissociated molecules were located in the top four or five monolayers at ice temperatures of 10, 20, 30, 60, and 90 K. Three photodesorption processes can occur upon X2O photodissociation: X atom photodesorption, OX radical photodesorption, and X2O (or HOD) molecule photodesorption. X2O (or HOD) photodesorption can occur after recombination of X and OX, or after an energetic X atom photofragment kicks a surrounding X2O molecule from the ice surface. Isotope effects are observed for the X atom and the OX radical photodesorption as well as for the kick-out photodesorption. However, no isotope effects were noticeable for the photodesorption of recombined X2O molecules. The average D atom photodesorption probabilities are about a factor 0.9 smaller than those for the H atom, regardless of the isotope of the surrounding ice system. Also, the kick-out mechanism is more likely to occur if a D photofragment is created upon dissociation than if an H atom is created. These observations can be explained by more efficient energy transfer from the D atom to water molecules than from the H atom. Reasoning based on the X2O phonon frequencies associated with the librational modes and energy transfer efficiencies explain why the OX radical photodesorption probabilities are noticeably larger if the OX radical desorbs from a D2O ice system than from an H2O ice system. Also, the OX radical photodesorption is more probable upon dissociation of DOX (X = H,D) than upon dissociation of HOX (X = H,D), because the initial kinetic energy of the OX radical is larger if the dissociation products are D + OX than H + OX. The branching ratio of OD/OH desorption following

  6. Cross sections and band strengths for the N2O/+/ /A 2Sigma+ to X 2Pi/ system produced by vacuum ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Lee, L. C.; Judge, D. L.

    1974-01-01

    Analysis of cross sections that have been obtained for the production of the N2O(+) (A 2Sigma+ to X 2Pi) fluorescence, using vacuum ultraviolet radiation between 462 and 755 A. The fluorescence spectra produced using incident photons of 715.6- and 754.9-A wavelengths are presented, as well as the relative fluorescence cross sections for the individual observed bands of the above-mentioned N2O(+) system. Finally, absolute cross sections for the production of the N2O(+) (A 2Sigma+ to X 2Pi) system are presented, as well as band strengths for the A 2Sigma+(0,0,0) to X 2Pi(n1,n2,0) fluorescence.

  7. A study of the atmospherically important reactions between dimethyl selenide (DMSe) and molecular halogens (X2 = Cl2, Br2, and I2) with ab initio calculations.

    PubMed

    Rhyman, Lydia; Armata, Nerina; Ramasami, Ponnadurai; Dyke, John M

    2012-06-14

    The atmospherically relevant reactions between dimethyl selenide (DMSe) and the molecular halogens (X(2) = Cl(2), Br(2), and I(2)) have been studied with ab initio calculations at the MP2/aug-cc-pVDZ level of theory. Geometry optimization calculations showed that the reactions proceed from the reagents to the products (CH(3)SeCH(2)X + HX) via three minima, a van der Waals adduct (DMSe:X(2)), a covalently bound intermediate (DMSeX(2)), and a product-like complex (CH(3)SeCH(2)X:HX). The computed potential energy surfaces are used to predict what molecular species are likely to be observed in spectroscopic experiments such as gas-phase photoelectron spectroscopy and infrared matrix isolation spectroscopy. It is concluded that, for the reactions of DMSe with Cl(2) and Br(2), the covalent intermediate should be seen in spectroscopic experiments, whereas, in the DMSe + I(2) reaction, the van der Waals adduct DMSe:I(2) should be observed. Comparison is made with previous related calculations and experiments on dimethyl sulfide (DMS) with molecular halogens. The relevance of the results to atmospheric chemistry is discussed. The DMSeX(2) and DMSe:X(2) intermediates are likely to be reservoirs of molecular halogens in the atmosphere which will lead on photolysis to ozone depletion.

  8. Flexible subunit stoichiometry of functional human P2X2/3 heteromeric receptors.

    PubMed

    Kowalski, Maria; Hausmann, Ralf; Schmid, Julia; Dopychai, Anke; Stephan, Gabriele; Tang, Yong; Schmalzing, Günther; Illes, Peter; Rubini, Patrizia

    2015-12-01

    The aim of the present work was to clarify whether heterotrimeric P2X2/3 receptors have a fixed subunit stoichiometry consisting of one P2X2 and two P2X3 subunits as previously suggested, or a flexible stoichiometry containing also the inverse subunit composition. For this purpose we transfected HEK293 cells with P2X2 and P2X3 encoding cDNA at the ratios of 1:2 and 4:1, and analysed the biophysical and pharmacological properties of the generated receptors by means of the whole-cell patch-clamp technique. The concentration-response curves for the selective agonist α,β-meATP did not differ from each other under the two transfection ratios. However, co-expression of an inactive P2X2 mutant and the wild type P2X3 subunit and vice versa resulted in characteristic distortions of the α,β-meATP concentration-response relationships, depending on which subunit was expressed in excess, suggesting that HEK293 cells express mixtures of (P2X2)1/(P2X3)2 and (P2X2)2/(P2X3)1 receptors. Whereas the allosteric modulators H+ and Zn2+ failed to discriminate between the two possible heterotrimeric receptor variants, the α,β-meATP-induced responses were blocked more potently by the competitive antagonist A317491, when the P2X2 subunit was expressed in deficit of the P2X3 subunit. Furthermore, blue-native PAGE analysis of P2X2 and P2X3 subunits co-expressed in Xenopus laevis oocytes and HEK293 cells revealed that plasma membrane-bound P2X2/3 receptors appeared in two clearly distinct heterotrimeric complexes: a (P2X2-GFP)2/(P2X3)1 complex and a (P2X2-GFP)1/(P2X3)2 complex. These data strongly indicate that the stoichiometry of the heteromeric P2X2/3 receptor is not fixed, but determined in a permutational manner by the relative availability of P2X2 and P2X3 subunits. PMID:26184350

  9. Flexible subunit stoichiometry of functional human P2X2/3 heteromeric receptors.

    PubMed

    Kowalski, Maria; Hausmann, Ralf; Schmid, Julia; Dopychai, Anke; Stephan, Gabriele; Tang, Yong; Schmalzing, Günther; Illes, Peter; Rubini, Patrizia

    2015-12-01

    The aim of the present work was to clarify whether heterotrimeric P2X2/3 receptors have a fixed subunit stoichiometry consisting of one P2X2 and two P2X3 subunits as previously suggested, or a flexible stoichiometry containing also the inverse subunit composition. For this purpose we transfected HEK293 cells with P2X2 and P2X3 encoding cDNA at the ratios of 1:2 and 4:1, and analysed the biophysical and pharmacological properties of the generated receptors by means of the whole-cell patch-clamp technique. The concentration-response curves for the selective agonist α,β-meATP did not differ from each other under the two transfection ratios. However, co-expression of an inactive P2X2 mutant and the wild type P2X3 subunit and vice versa resulted in characteristic distortions of the α,β-meATP concentration-response relationships, depending on which subunit was expressed in excess, suggesting that HEK293 cells express mixtures of (P2X2)1/(P2X3)2 and (P2X2)2/(P2X3)1 receptors. Whereas the allosteric modulators H+ and Zn2+ failed to discriminate between the two possible heterotrimeric receptor variants, the α,β-meATP-induced responses were blocked more potently by the competitive antagonist A317491, when the P2X2 subunit was expressed in deficit of the P2X3 subunit. Furthermore, blue-native PAGE analysis of P2X2 and P2X3 subunits co-expressed in Xenopus laevis oocytes and HEK293 cells revealed that plasma membrane-bound P2X2/3 receptors appeared in two clearly distinct heterotrimeric complexes: a (P2X2-GFP)2/(P2X3)1 complex and a (P2X2-GFP)1/(P2X3)2 complex. These data strongly indicate that the stoichiometry of the heteromeric P2X2/3 receptor is not fixed, but determined in a permutational manner by the relative availability of P2X2 and P2X3 subunits.

  10. The Conterminous United States Mineral Assessment Program; background information to accompany folio of geologic, geophysical, geochemical, mineral-occurrence, mineral-resource potential, and mineral-production maps of the Charlotte 1 degree x 2 degrees Quadrangle, North Carolina and South Carolina

    USGS Publications Warehouse

    Gair, Jacob Eugene; Goldsmith, Richard; Daniels, D.L.; Griffitts, W.R.; DeYoung, J.H.; Lee, M.P.

    1986-01-01

    This Circular and the folio of separately published maps described herein are part of a series of reports compiled under the Conterminous United States Mineral Assessment Program ICUSMAP). The folio on the Charlotte 1 degree ? 2 degree quadrangle, North Carolina and South Carolina, includes (1) a geologic map; (2) four geophysical maps; (3) geochemical maps for metamorphic heavy minerals, copper, lead and artifacts, zinc, gold, tin, beryllium, niobium, tungsten, molybdenum, titanium, cobalt, lithium, barium, antimony-arsenic-bismuth-cadmium, thorium-cerium-monazite, and limonite; (4) mineral-occurrence maps for kyanite-sillimanite-lithium-mica-feldspar-copper-lead-zinc, gold-quartz-barite-fluorite, iron-thorium-tin-niobium, and construction materials-gemstones; (5) mineral-resource potential maps for copper-lead-zinc-combined base metals, gold, tin-tungsten, beryllium-molybdenum-niobium, lithium-kyanite- sillimanitebarite, thorium (monazite)-uranium, and construction materials; and (6) mineral-production maps. The Charlotte quadrangle is mainly within the Piedmont physiographic province and extends from near the Coastal Plain on the southeast into the Blue Ridge province on the northwest for a short distance. Parts of six lithotectonic belts are present--the Blue Ridge, the Inner Piedmont, the Kings Mountain belt, the Charlotte belt, the Carolina slate belt, and the Wadesboro basin. Igneous, metamorphic, and sedimentary rocks are present and range in age from Proterozoic to Mesozoic; alluvial sediments of Quaternary age occur along rivers and larger streams. Rocks of the Blue Ridge include Middle Proterozoic granitoid gneiss intruded by Late Proterozoic granite; Late Proterozoic paragneiss, schist, and other metasedimentary and metavolcaniclastic rocks (Ashe and Grandfather Mountain Formations); Late Proterozoic and Early Cambrian metasedimentary rocks (Chilhowee Group); and Early Cambrian sedimentary rocks (Shady Dolomite). Paleozoic granites intrude the

  11. Regulation of P2X2 Receptors by the Neuronal Calcium Sensor VILIP1

    PubMed Central

    Chaumont, Severine; Compan, Vincent; Toulme, Estelle; Richler, Esther; Housley, Gary D.; Rassendren, Francois; Khakh, Baljit S.

    2012-01-01

    Extracellular adenosine triphosphate (ATP) activates P2X receptors, which are involved in diverse physiological functions. Using a proteomic approach, we identified the neuronal calcium sensor VILIP1 as interacting with P2X2 receptors. We found that VILIP1 forms a signaling complex in vitro and in vivo with P2X2 receptors and regulates P2X2 receptor sensitivity to ATP, peak response, surface expression, and diffusion. VILIP1 constitutively binds to P2X2 receptors and displays enhanced interactions in an activation- and calcium-dependent manner owing to exposure of its binding segment in P2X2 receptors. VILIP1-P2X2 interactions are also enhanced in hippocampal neurons during conditions of action potential firing known to trigger P2X2 receptor activation. Our data thus reveal a previously unrecognized function for the neuronal calcium sensor protein VILIP1 and a mechanism for regulation of ATP-dependent P2X receptor signaling by neuronal calcium sensors. PMID:18922787

  12. Origin of the X1X1X2X2/X1X2Y sex chromosome system of Harttia punctata (Siluriformes, Loricariidae) inferred from chromosome painting and FISH with ribosomal DNA markers.

    PubMed

    Blanco, Daniel Rodrigues; Vicari, Marcelo Ricardo; Lui, Roberto Laridondo; Artoni, Roberto Ferreira; de Almeida, Mara Cristina; Traldi, Josiane Baccarin; Margarido, Vladimir Pavan; Moreira-Filho, Orlando

    2014-04-01

    Harttia is a genus in the subfamily Loricariinae that accommodates fishes popularly known as armored catfishes. They show extensive karyotypic diversity regarding interspecific numerical/structural variation of the karyotypes, with the presence of the XX/XY1Y2 multiple sex chromosome system, as found in H. carvalhoi. In this context, this study aimed to characterize Harttia punctata chromosomally, for the first time, and to infer the rearrangements that originated the X1X1X2X2/X1X2Y multiple sex chromosome system present in this species. The data obtained in this study, with classical (Giemsa, C-banding and AgNORs) and molecular methodologies (fluorescence in situ hybridization) and chromosome microdissection, indicated that a translocation between distinct acrocentric chromosomes bearing rRNA genes, accompanied by deletions in both chromosomes, might have originated the neo-Y chromosome in this species. The data also suggest that the multiple sex chromosome systems present in H. carvalhoi and H. punctata had an independent origin, evidencing the recurrence of chromosome alterations in species from this genus.

  13. Chromosomal distribution of two multigene families and the unusual occurrence of an X1X1X2X2/X1X2Y sex chromosome system in the dolphinfish (Coryphaenidae): an evolutionary perspective.

    PubMed

    Soares, R X; Bertollo, L A C; Cioffi, M B; Costa, G W W F; F Molina, W

    2014-01-01

    Dolphinfishes (Coryphaenidae) are pelagic predators distributed throughout all tropical and subtropical oceans and are very important for commercial, traditional, and sport fishing. This small family contains the Coryphaena hippurus and Coryphaena equiselis species whose chromosomal aspects remain unknown, despite recent advances in cytogenetic data assimilation for Perciformes. In this study, both species were cytogenetically analyzed using different staining techniques (C-, Ag-, and CMA3 banding) and fluorescence in situ hybridization, to detect 18S rDNA and 5S rDNA. C. hippurus females exhibit 2n = 48 chromosomes, with 2m+4sm+42a (NF = 54). In C. equiselis, where both sexes could be analyzed, females displayed 2n = 48 chromosomes (2m+6sm+40a) and males exhibited 2n = 47 chromosomes (3m+6sm+38a) (NF = 56), indicating the presence of X1X1X2X2/X1X2Y multiple sex chromosomes. Sex-chromosome systems are rare in Perciformes, with this study demonstrating the first occurrence in a marine pelagic species. It remains unknown as to whether this system extends to other populations; however, these data are important with respect to evolutionary, phylogenetic, and speciation issues, as well as for elucidating the genesis of this unique sex system. PMID:24782001

  14. Investigation of hole mobility by photoorientation. X -2 ions in glasses

    NASA Astrophysics Data System (ADS)

    Vorobiev, A. Kh.; Gurman, V. S.

    1992-11-01

    The mobility of the hole defects in the dark and at irradiation by light has been investigated in halide-containing glassy matrices. The UV and ESR spectra of the holes are identical to the ones for X -2 in liquid solution. Defects move in the solid by an electron-transfer mechanism. The UV spectra of X -2 are shifted in the course of the irradiation. The reversible shift is similar to spectral diffusion in hole-burning experiments. Photoorientation of X -2 manifests itself as light-induced anisotropy of the samples. The quantum yield of the photoinduced jump of X -2 has been estimated from the kinetics of photoorientation. The energy distribution of traps has been obtained by studying the temperature dependence. Theoretical models of hole mobility are discussed. The potential surface is concluded to be characterized by both site and bond disorder. The percolation model is most adequate to rationalize the experiments.

  15. Comparisons of modified Vasco X-2 and AISI 9310 gear steels

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Zaretsky, E. V.

    1980-01-01

    Endurance tests were conducted with four groups of spur gears manufactured from three heats of consumable electrode vacuum melted (CVM) modified Vasco X-2. Endurance tests were also conducted with gears manufactured from CVM AISI 9310. Bench type rolling element fatigue tests were conducted with both materials. Hardness measurements were made to 811 K. There was no statistically significant life difference between the two materials. Life differences between the different heats of modified Vasco X-2 can be attributed to heat treat variation and resultant hardness. Carburization of gear flanks only can eliminate tooth fracture as a primary failure mode for modified Vasco X-2. However, a tooth surface fatigue spall can act as a nucleus of a tooth fracture failure for the modified Vasco X-2.

  16. ISS Update: SpaceX 2 Lead Visiting Vehicle Officer Dorrie Tomayko

    NASA Video Gallery

    NASA Public Affairs Officer Brandi Dean conducts an interview with SpaceX 2 Lead Visiting Vehicle Officer Dorrie Tomayko about the second commercial resupply mission to the International Space Stat...

  17. Regulation of GABAA Receptor Dynamics by Interaction with Purinergic P2X2 Receptors*

    PubMed Central

    Shrivastava, Amulya Nidhi; Triller, Antoine; Sieghart, Werner; Sarto-Jackson, Isabella

    2011-01-01

    γ-Aminobutyric acid type A receptors (GABAARs) in the spinal cord are evolving as an important target for drug development against pain. Purinergic P2X2 receptors (P2X2Rs) are also expressed in spinal cord neurons and are known to cross-talk with GABAARs. Here, we investigated a possible “dynamic” interaction between GABAARs and P2X2Rs using co-immunoprecipitation and fluorescence resonance energy transfer (FRET) studies in human embryonic kidney (HEK) 293 cells along with co-localization and single particle tracking studies in spinal cord neurons. Our results suggest that a significant proportion of P2X2Rs forms a transient complex with GABAARs inside the cell, thus stabilizing these receptors and using them for co-trafficking to the cell surface, where P2X2Rs and GABAARs are primarily located extra-synaptically. Furthermore, agonist-induced activation of P2X2Rs results in a Ca2+-dependent as well as an apparently Ca2+-independent increase in the mobility and an enhanced degradation of GABAARs, whereas P2X2Rs are stabilized and form larger clusters. Antagonist-induced blocking of P2XRs results in co-stabilization of this receptor complex at the cell surface. These results suggest a novel mechanism where association of P2X2Rs and GABAARs could be used for specific targeting to neuronal membranes, thus providing an extrasynaptic receptor reserve that could regulate the excitability of neurons. We further conclude that blocking the excitatory activity of excessively released ATP under diseased state by P2XR antagonists could simultaneously enhance synaptic inhibition mediated by GABAARs. PMID:21343285

  18. State-to-state quantum dynamics of the N(4S) + CH(X 2Π) → CN(X 2Σ+,A2Π) + H(2S) reactions

    NASA Astrophysics Data System (ADS)

    Hu, Xixi; Xie, Changjian; Xie, Daiqian; Guo, Hua

    2013-09-01

    The reactions between N(4S) and CH(X2Π) lead to H(2S) plus CN in its two lowest electronic states (X2Σ+ and A2Π), which are responsible for the interstellar CN formation. Accurate quantum dynamics of these reactions are investigated on new global potential energy surfaces of the two lowest-lying triplet states of HCN (13A' and 13A″) fitted to more than 37 000 points at the internally contracted multi-reference configuration interaction level with the Davidson correction. The pathways for these highly exothermic and barrierless reactions feature both the HCN and HNC wells. Long-lived resonances supported by these wells manifest in reaction probabilities as numerous oscillations, particularly for low J partial waves. The 13A″ state is found to be more reactive than the 13A' state, due apparently to its more attractive nature in the entrance channel. The CN products in both electronic states are highly excited in both vibrational and rotational degrees of freedom. The near forward-backward symmetric differential cross sections are consistent with a complex-forming mechanism.

  19. X-2 on ramp with B-50 mothership and support crew

    NASA Technical Reports Server (NTRS)

    1956-01-01

    Air Force test pilot Capt. Iven Kincheloe stands in front of the Bell X-2 (46-674) on the ramp at Edwards Air Force Base, California. Behind the X-2 are ground support personnel, the B-50 launch aircraft and crew, chase planes, and support vehicles. Kincheloe had flown nearly 100 combat missions in Korea in an F-86 and was credited with shooting down 10 enemy aircraft. He then graduated from the Empire Test Pilot's School in Great Britain in December 1954, whereupon he was assigned to Edwards Air Force Base. He made four powered flights in the X-2. On September 7, 1956, he reached an altitude of 126,200 feet. After the death of Capt. Mel Apt and the loss of the X-2 #1 on September 27, 1956, in the first Mach 3 flight, Kincheloe was assigned as the Air Force project pilot for the X-15. Before he had a chance to fly that rocket-powered aircraft, Kincheloe himself lost his life on July 26, 1958, in an F-104 accident. The X-2 was a swept-wing, rocket-powered aircraft designed to fly faster than Mach 3 (three times the speed of sound). It was built for the U.S. Air Force by the Bell Aircraft Company, Buffalo, New York. The X-2 was flown to investigate the problems of aerodynamic heating as well as stability and control effectiveness at high altitudes and high speeds (in excess of Mach 3). Bell aircraft built two X-2 aircraft. These were constructed of K-monel (a copper and nickel alloy) for the fuselage and stainless steel for the swept wings and control surfaces. The aircraft had ejectable nose capsules instead of ejection seats because the development of ejection seats had not reached maturity at the time the X-2 was conceived. The X-2 ejection canopy was successfully tested using a German V-2 rocket. The X-2 used a skid-type landing gear to make room for more fuel. The airplane was air launched from a modified Boeing B-50 Superfortress Bomber. X-2 Number 1 made its first unpowered glide flight on Aug. 5, 1954, and made a total of 17 (4 glide and 13 powered) flights

  20. The Recent Outburst of SMC X-2 as seen by Swift, MAXI and NuSTAR

    NASA Astrophysics Data System (ADS)

    Kennea, Jamie; Coe, Malcolm J.; Laycock, Silas; Bird, Tony; Bartlett, Elizabeth; Townsend, Lee; McBride, Vanessa; Corbet, Robin; Haberl, Frank; Vasilopoulos, Georgios

    2016-04-01

    We present results from the latest outburst of the Be/X-ray binary system SMC X-2, which in late 2015 entered it's first X-ray outburst since 2000. SMC X-2 was first discovered in 1977 by the SAS-3 satellite, and hosts a 2.37s period pulsar. Regular, almost daily, Swift observations of SMC X-2 were performed during the entirety of the latest outburst, from first detection by MAXI to it’s rapid turn off and return back to quiescence. These observations have allowed us to measure with the flux, spectral and temporal properties of SMC X-2. Timing analysis of observation by the Swift X-ray telescope allowed us to track the evolution of the pulsar spin period, and in addition modeling of the orbital parameters of the system by measuring changes in the pulsar spin period due to Doppler effects. In addition we report on an observation of SMC X-2 taken with NuSTAR, which allowed both to better measure the continuum fit above 10 keV, and to perform a sensitive measure of the pulse profile and period of the source.

  1. Stable monolayer honeycomb-like structures of RuX2 (X =S,Se)

    NASA Astrophysics Data System (ADS)

    Ersan, Fatih; Cahangirov, Seymur; Gökoǧlu, Gökhan; Rubio, Angel; Aktürk, Ethem

    2016-10-01

    Recent studies show that several metal oxides and dichalcogenides (M X2) , which exist in nature, can be stable in two-dimensional (2D) form and each year several new M X2 structures are explored. The unstable structures in H (hexagonal) or T (octahedral) forms can be stabilized through Peierls distortion. In this paper, we propose new 2D forms of RuS2 and RuSe2 materials. We investigate in detail the stability, electronic, magnetic, optical, and thermodynamic properties of 2D Ru X2 (X =S,Se) structures from first principles. While their H and T structures are unstable, the distorted T structures (T'-Ru X2) are stable and have a nonmagnetic semiconducting ground state. The molecular dynamic simulations also confirm that T'-Ru X2 systems are stable even at 500 K without any structural deformation. T'-RuS2 and T'-RuSe2 have indirect band gaps with 0.745 eV (1.694 eV with HSE) and 0.798 eV (1.675 eV with HSE) gap values, respectively. We also examine their bilayer and trilayer forms and find direct and smaller band gaps. We find that AA stacking is more favorable than the AB configuration. The new 2D materials obtained can be good candidates with striking properties for applications in semiconductor electronic, optoelectronic devices, and sensor technology.

  2. Endothelin-1 production by normal human cultured keratinocytes and its regulation.

    PubMed

    Inoue, H; Wakisaka, N; Tane, N; Ando, K; Isono, E; Yamanaka, M; Aihara, M; Ishida, H

    1994-01-01

    The possibility that cultured keratinocytes produce endothelins were investigated. The results showed that cultured keratinocytes derived from normal human skin produce endothelin-1. Moreover, keratinocyte endothelin-1 production was completely inhibited by the presence of actinomycin D in the medium. As in the case of endothelial cells, recombinant interleukin-1beta was capable of promoting endothelin-1 production in keratinocytes, whereas herapin inhibited it. Thrombin also inhibited endothelin-1 production. These results indicate that the mechanism of endothelin-1 production in keratinocytes is slightly different from the mechanism in vascular endothelial cells.

  3. HETG Observations of the Extragalactic Z-source LMC X-2

    NASA Astrophysics Data System (ADS)

    Canizares, Claude

    2013-09-01

    LMC X-2 is the only Z-source known outside our own Galaxy. We also seek to detect and resolve broad line emission and investigate line flux and shift variability possibly in correlation with its Z-pattern. Its location outside the Galactic Halo also allow to study differences in ISM and local IGM absortions. We also seek to detect and resolve broad line emission. As previously done for Cyg X-2 we also investigate line flux and shift variability possibly in correlation with its Z-pattern.

  4. Cygnus X-2: The Descendant of an Intermediate-Mass X-Ray Binary

    NASA Astrophysics Data System (ADS)

    Podsiadlowski, Ph.; Rappaport, S.

    2000-02-01

    The X-ray binary Cygnus X-2 (Cyg X-2) has recently been shown to contain a secondary that is much more luminous and hotter than is appropriate for a low-mass subgiant. We present detailed binary-evolution calculations which demonstrate that the present evolutionary state of Cyg X-2 can be understood if the secondary had an initial mass of around 3.5 Msolar and started to transfer mass near the end of its main-sequence phase (or, somewhat less likely, just after leaving the main sequence, as recently suggested independently by A. R. King & H. Ritter). Most of the mass of the secondary must have been ejected from the system during an earlier rapid mass transfer phase. In the present phase, the secondary has a mass of around 0.5 Msolar with a nondegenerate helium core. It is burning hydrogen in a shell, and mass transfer is driven by the advancement of the burning shell. Cyg X-2 therefore is related to a previously little studied class of intermediate-mass X-ray binaries (IMXBs). We suggest that perhaps a significant fraction of X-ray binaries presently classified as low-mass X-ray binaries may be descendants of IMXBs and discuss some of the implications.

  5. RXTE/ASM Observations Of SS 433 And Cygnus X-2

    NASA Astrophysics Data System (ADS)

    Hoffman, Lisa; Mason, P. A.

    2010-01-01

    We present a dynamic period search analysis of the X-ray binaries SS 433 and Cygnus X-2 using data from the Rossi X-Ray Timing Explorer All Sky Monitor (RXTE/ASM) spanning over 13 years. We report the detection of a period in SS 433 near 162 days. This may be the first detection of the disk precession period in X-rays. We detect an 81.8 day period in the object Cygnus X-2. The RXTE/ASM light curve is inconsistent with the 77.7 day X-ray period of Wijnands et al. (1996), which was based on a small subset of the RXTE/ASM data combined with data from VELA 5B, and Ariel 5 All-Sky Monitors. Since Cygnus X-2 displays periodic behavior that seems to come and go, producing different best-fit periods on time scales of a few years; we suggest that Cygnus X-2 exhibits quasi-periodic oscillations of about 80 days. This research is supported by a grant from the New Mexico Space Grant Consortium.

  6. Toxicological Assessment of ISS Air Quality: SpaceX-2 First Ingress

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie

    2013-01-01

    One mini-grab sample container (M-GSC) was collected by crew members onboard ISS during first ingress into SpaceX-2 on March 3, 2013, three days after late cargo loading and a pre-launch clean air purge. Recoveries of the three surrogate standards from the m-GSC were: 13C-acetone, 97%; fluorobenzene, 95%; and chlorobenzene, 68%.

  7. The 2 x 2 Model of Perfectionism: A Comparison across Asian Canadians and European Canadians

    ERIC Educational Resources Information Center

    Franche, Veronique; Gaudreau, Patrick; Miranda, Dave

    2012-01-01

    The 2 x 2 model of perfectionism posits that the 4 within-person combinations of self-oriented and socially prescribed perfectionism (i.e., pure SOP, mixed perfectionism, pure SPP, and nonperfectionism) can be distinctively associated with psychological adjustment. This study examined whether the relationship between the 4 subtypes of…

  8. 7. Photocopy of photographca. 1927 (2 1/4 X 2 1/4' ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Photocopy of photograph--ca. 1927 (2 1/4 X 2 1/4' negative) DETAIL SHOWING ADAPTATION THAT ALLOWED USE OF UPPER END OF ORIGINAL FLUME AND LOWER END JUST RECONSTRUCTED - Power Flume No. 1, Tacoma, La Plata County, CO

  9. Visualization of the trimeric P2X2 receptor with a crown-capped extracellular domain.

    PubMed

    Mio, Kazuhiro; Kubo, Yoshihiro; Ogura, Toshihiko; Yamamoto, Tomomi; Sato, Chikara

    2005-11-25

    The P2X2 purinergic receptor permeates cationic ions in response to stimulation by ATP and mediates fast synaptic transmission. Here, we purified the P2X2 receptor using baculovirus-Sf9 cell expression system and observed its structure using electron microscopy. The FLAG-tagged P2X2 receptor, which has intact ion channel function, was purified to be a single peak by affinity purification and gel filtration chromatography. It was confirmed to be a trimer by introducing cross-linking. Negatively stained P2X2 protein images were homogeneous and picked up by automated pick-up programs, aligned, and classified using the modified growing neural gas network method. Similarly oriented projections were averaged to decrease the signal-to-noise ratio. These images demonstrate an inverted three-sided pyramid with the dimensions of 215 A in height and 200 A in side length. It is composed of a high-density trunk and a stain-permeable swollen extracellular domain of a crown-shaped structure. The internal cavities and constituent segments were clearly demonstrated in both the raw images and the averaged images. The threefold symmetrical top view demonstrates the first visual evidence of the trimeric composition of the P2X receptor family. PMID:16219297

  10. SWIFT MONITORING OF CYGNUS X-2: INVESTIGATING THE NEAR-ULTRAVIOLET-X-RAY CONNECTION

    SciTech Connect

    Rykoff, E. S.; Cackett, E. M.; Miller, J. M.

    2010-08-20

    The neutron star X-ray binary (NSXRB) Cyg X-2 was observed by the Swift satellite 51 times over a 4 month period in 2008 with the X-ray Telescope (XRT), UV/optical telescope, and Burst Alert Telescope (BAT) instruments. During this campaign, we observed Cyg X-2 in all three branches of the Z track (horizontal, normal, and flaring branches). We find that the NUV emission is uncorrelated with the soft X-ray flux detected with the XRT and is anticorrelated with the BAT X-ray flux and the hard X-ray color. The observed anticorrelation is inconsistent with simple models of reprocessing as the source of the NUV emission. The anticorrelation may be a consequence of the high inclination angle of Cyg X-2, where NUV emission is preferentially scattered by a corona that expands as the disk is radiatively heated. Alternatively, if the accretion disk thickens as Cyg X-2 goes down the normal branch toward the flaring branch, this may be able to explain the observed anticorrelation. In these models, the NUV emission may not be a good proxy for m-dot in the system. We also discuss the implications of using Swift/XRT to perform spectral modeling of the continuum emission of NSXRBs.

  11. Gender Differences in the Factor Structure of the 2x2 Achievement Goal Framework

    ERIC Educational Resources Information Center

    Alkharusi, Hussain; Aldhafri, Said

    2010-01-01

    The present study examined gender differences in the factor structure of the 2x2 achievement goal framework using a multi-sample invariance analysis. A total of 117 male and 125 female undergraduate teacher education students completed Elliot and Murayama's (2008) Achievement Goal Questionnaire-Revised (AGQ-R). Results provided empirical evidence…

  12. Extending the 2 x 2 Achievement Goal Framework: Development of a Measure of Scientific Achievement Goals

    ERIC Educational Resources Information Center

    Deemer, Eric D.; Carter, Alice P.; Lobrano, Michael T.

    2010-01-01

    The current research sought to extend the 2 x 2 achievement goal framework by developing and testing the Achievement Goals for Research Scale (AGRS). Participants (N = 317) consisted of graduate students in the life, physical, and behavioral sciences. A principal components analysis (PCA) extracted five components accounting for 72.59% of the…

  13. Window type: paired 3x2 multipaned steel window flanked by 1x3 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Window type: paired 3x2 multipaned steel window flanked by 1x3 multipaned steel casements, breaking building corner. Broad overhanging eave also illustrated. Second story detail. Building 13, facing east - Harbor Hills Housing Project, 26607 Western Avenue, Lomita, Los Angeles County, CA

  14. Window types: (from left to right) Pair of 2x2 multipaned ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Window types: (from left to right) Pair of 2x2 multipaned steel casements; triplet of 1x4 multipaned steel casements (center panel fixed); 1x3 multipaned steel casements. Building 20, facing southwest - Harbor Hills Housing Project, 26607 Western Avenue, Lomita, Los Angeles County, CA

  15. Understanding Student Goal Orientation Tendencies to Predict Student Performance: A 2x2 Achievement Goal Orientation

    ERIC Educational Resources Information Center

    Miller, Mark Alan

    2013-01-01

    The study tested the 2X2 model of the Achievement Goal Orientation (AGO) theory in a military technical training environment while using the Air Force Officers Qualifying Test's academic aptitude score to control for the differences in the students' academic aptitude. The study method was quantitative and the design was correlational.…

  16. Procrastination and the 2 x 2 Achievement Goal Framework in Malaysian Undergraduate Students

    ERIC Educational Resources Information Center

    Ganesan, Rajalakshmi; Mamat, Norul Hidayah Bt; Mellor, David; Rizzuto, Laura; Kolar, Christina

    2014-01-01

    The present study investigated academic procrastination in the context of the 2 x 2 goal achievement theoretical framework within a population of 450 Malaysian undergraduate students, aged 18 to 25 years. Participants completed the Achievement Goal Questionnaire and the Tuckman Procrastination Test. Approach dimensions of both the mastery and…

  17. Cohen's Linearly Weighted Kappa Is a Weighted Average of 2 x 2 Kappas

    ERIC Educational Resources Information Center

    Warrens, Matthijs J.

    2011-01-01

    An agreement table with [n as an element of N is greater than or equal to] 3 ordered categories can be collapsed into n - 1 distinct 2 x 2 tables by combining adjacent categories. Vanbelle and Albert ("Stat. Methodol." 6:157-163, 2009c) showed that the components of Cohen's weighted kappa with linear weights can be obtained from these n - 1…

  18. Absolute rate coefficients over extended temperature ranges and mechanisms of the CF(X(2)Pi) reactions with F(2), Cl(2) and O(2).

    PubMed

    Vetters, B; Dils, B; Nguyen, T L; Vereecken, L; Carl, S A; Peeters, J

    2009-06-01

    The absolute rate coefficients of the reactions of the carbyne-radical CF(X(2)Pi, nu = 0) with O(2), F(2) and Cl(2) have been measured over extended temperature ranges, using pulsed-laser photodissociation-laser-induced fluorescence (PLP-LIF) techniques. The CF(X(2)Pi) radicals were generated by KrF excimer laser 2-photon photolysis of CF(2)Br(2) at 248 nm and the real-time exponential decays of CF(X(2)Pi, nu = 0) at varying coreactant concentrations, in large excess, were monitored by LIF (A(2)Sigma(+), nu' = 1 <-- X(2)Pi, nu'' = 0 transition). The experimental bimolecular rate coefficients of the CF(X(2)Pi) reactions with F(2) and Cl(2) can be described by simple Arrhenius expressions: k(F2)(295-408 K) = (1.5 +/- 0.2) x 10(-11) exp[-(370 +/- 40)K/T] cm(3) molecule(-1) s(-1); and k(Cl2)(295-392 K) = (6.1 +/- 2.1) x 10(-12) exp[+(280 +/- 120)K/T]. The k(F2)(T) and k(Cl2)(T) results can be rationalized in terms of direct halogen-atom abstraction reactions in which the radical character of CF dominates; a quantum chemical CBS-Q//BHandHLYP/6-311G(d,p) study confirms that the ground state reactants CF(X(2)Pi) + F(2)(X(1)Sigma) connect directly with the ground-state products CF(2)(X(1)A(1)) + F((2)P) via a nearly barrierless F-atom abstraction route. The rate coefficient of CF(X(2)Pi) + O(2) can be represented by a two-term Arrhenius expression: k(O2)(258-780 K) = 1.1 x 10(-11) exp(-850 K/T) + 2.3 x 10(-13) exp(500 K/T), with a standard deviation of 5%. The first term dominates at higher temperatures T and the second at lower T where a negative temperature dependence is observed (<290 K). Quantum chemical computations at the CBS-QB3 and CCSD(T)/aug-cc-pVDZ levels of theory show that the k(O2)(T) behaviour is consistent with a change of the dominant rate-determining mechanism from a carbyne-type insertion into the O-O bond at high T to a radical-radical combination at low T.

  19. Structures and magnetism of two types of c(2x2)-Mn/Pd(001) surface alloys

    SciTech Connect

    Tsuboi, N.; Okuyama, H.; Aruga, T.

    2005-05-15

    Mn/Pd(001) surface alloy was investigated by a tensor low-energy electron diffraction (LEED) analysis. After deposition of Mn on Pd(001) at room temperature, the surface was annealed at 570-620 K, which produced two types of c(2x2) surface alloys, according to the Mn coverage. At a low-Mn coverage, we obtained a Pd-capped c(2x2) surface, in which the first layer was composed of a (1x1)-Pd layer, and the second layer was a c(2x2)-MnPd mixed layer [{alpha}-c(2x2)]. The deposition of greater amounts of Mn followed by annealing resulted in another c(2x2) surface, in which Mn atoms existed in the substitutional sites of the first and third layers [{beta}-c(2x2)]. The first layer consisted of a c(2x2)-MnPd mixed layer, the second layer was a (1x1)-Pd layer, and the third layer was another c(2x2)-MnPd mixed layer. The structure of the {beta}-c(2x2) surface qualitatively agreed with the one previously investigated by LEED. These two types of surface alloys, {alpha}-c(2x2) and {beta}-c(2x2), may be considered as being precursors to the formation of the bulk MnPd{sub 3} alloy. We also investigated the magnetic properties of the {alpha}-c(2x2) and {beta}-c(2x2) surfaces by using surface magneto-optic Kerr effect (MOKE) and self-consistent, total-energy calculations. The MOKE measurements for both surface alloys show no hysterisis loop, even at 10 K. The total-energy calculation shows that Mn atoms have a local-spin moment of 3.9-4.1 {mu}{sub B} and that they are antiferromagnetically ordered in the ground state.

  20. In search of the X2BO and X2BS (X = H, F) free radicals: ab initio studies of their spectroscopic signatures.

    PubMed

    Clouthier, Dennis J

    2014-12-28

    The F2BO free radical is a known, although little studied, species but similar X2BY (X = H, D, F; Y = O, S) molecules are largely unknown. High level ab initio methods have been used to predict the molecular structures, vibrational frequencies (in cm(-1)), and relative energies of the ground and first two excited electronic states of these free radicals, as an aid to their eventual spectroscopic identification. The chosen theoretical methods and basis sets were tested on F2BO and found to give good agreement with the known experimental quantities. In particular, complete basis set extrapolations of coupled-cluster single and doubles with perturbative triple excitations/aug-cc-pVXZ (X = 3, 4, 5) energies gave excellent electronic term values, due to small changes in geometry between states and the lack of significant multireference character in the wavefunctions. The radicals are found to have planar C2v geometries in the X̃(2)B2 ground state, the low-lying Ã(2)B1 first excited state, and the higher B̃(2)A1 state. Some of these radicals have very small ground state dipole moments hindering microwave measurements. Infrared studies in matrices or in the gas phase may be possible although the fundamentals of H2BO and H2BS are quite weak. The most promising method of identifying these species in the gas phase appears to be absorption or laser-induced fluorescence spectroscopy through the allowed B̃-X̃ transitions which occur in the visible-near UV region of the electromagnetic spectrum. The ab initio results have been used to calculate the Franck-Condon profiles of the absorption and emission spectra, and the rotational structure of the B̃-X̃0(0)(0) bands has been simulated. The calculated single vibronic level emission spectra provide a unique, readily recognizable fingerprint of each particular radical, facilitating the experimental identification of new X2BY species in the gas phase.

  1. Web-based cognitive bias modification for problem drinkers: protocol of a randomised controlled trial with a 2x2x2 factorial design

    PubMed Central

    2013-01-01

    Background The automatic tendency to attend to, positively evaluate and approach alcohol related stimuli has been found to play a causal role in problematic alcohol use and can be retrained by computerised Cognitive Bias Modification (CBM). In spite of CBMs potential as an internet intervention, little is known about the efficacy of web-based CBM. The study described in this protocol will test the effectiveness of web-based CBM in a double blind randomised controlled trial with a 2 (attention bias retraining: real versus placebo) x 2 (alcohol/no-go training: real versus placebo) x 2 (approach bias retraining: real versus placebo) factorial design. Methods/design The effectiveness of 12 sessions of CBM will be examined among problem drinkers aged 18–65 who are randomly assigned to one of the eight CBM conditions, after completing two modules of a validated cognitive behavioural intervention, DrinkingLess. The primary outcome measure is the change in alcohol use. It is expected that, for each of the CBM interventions, participants in the real CBM conditions will show a greater decrease in alcohol use than participants in the placebo conditions. Secondary outcome measures include the percentage of participants drinking within the limits for sensible drinking. Possible mediating (change in automatic biases) and moderating (working memory, inhibition) factors will be examined, as will the comparative cost-effectiveness of the various CBM strategies. Discussion This study will be the first to test the relative efficacy of various web-based CBM strategies in problem drinkers. If proven effective, CBM could be implemented as a low-cost, low-threshold adjuvant to CBT-based online interventions for problem drinkers. Trial registration Netherlands Trial register: NTR3875. PMID:23870532

  2. Radiation and collisional energy transfer among the A 2Pi(i) and X 2Sigma(+) states of CN

    NASA Technical Reports Server (NTRS)

    Huang, Yuhui; Lu, Richang; Halpern, Joshua B.

    1993-01-01

    Laser-photolysis-laser-induced-fluorescence methods are used to characterize the collisional energy transfer between CN (A 2Pi(i) and (X 2Sigma(+)) states and to measure radiative lifetimes of the (A 2Pi(i)) v-prime = 2-7 vibrational levels. In addition, use of the A 2Pi(i) - X 2Sigma(+) system for the laser-induced-fluorescence determination of (X 2Sig(+)) populations is demonstrated and discussed.

  3. Design and construction of the X-2 two-stage free piston driven expansion tube

    NASA Technical Reports Server (NTRS)

    Doolan, Con

    1995-01-01

    This report outlines the design and construction of the X-2 two-stage free piston driven expansion tube. The project has completed its construction phase and the facility has been installed in the new impulsive research laboratory where commissioning is about to take place. The X-2 uses a unique, two-stage driver design which allows a more compact and lower overall cost free piston compressor. The new facility has been constructed in order to examine the performance envelope of the two-stage driver and how well it couple to sub-orbital and super-orbital expansion tubes. Data obtained from these experiments will be used for the design of a much larger facility, X-3, utilizing the same free piston driver concept.

  4. Prediction of intrinsic motivation and sports performance using 2 x 2 achievement goal framework.

    PubMed

    Li, Chiung-Huang; Chi, Likang; Yeh, Suh-Ruu; Guo, Kwei-Bin; Ou, Cheng-Tsung; Kao, Chun-Chieh

    2011-04-01

    The purpose of this study was to examine the influence of 2 x 2 achievement goals on intrinsic motivation and performance in handball. Participants were 164 high school athletes. All completed the 2 x 2 Achievement Goals Questionnaire for Sport and the Intrinsic Motivation subscale of the Sport Motivation Scale; the coach for each team rated his athletes' overall sports performance. Using simultaneous-regression analyses, mastery-approach goals positively predicted both intrinsic motivation and performance in sports, whereas performance-avoidance goals negatively predicted sports performance. These results suggest that athletes who pursue task mastery and improvement of their competence perform well and enjoy their participation. In contrast, those who focus on avoiding normative incompetence perform poorly.

  5. [Endoluminal fundoplication (ELF) with EsophyX2 for gastroesophageal reflux desease (GERD)].

    PubMed

    Nicolau, A E; Lobonţiu, A; Constantinescu, G

    2009-01-01

    GERD is a frequent, evolving, life quality-impairing disease. In addition to medication and laparoscopic fundoplication we have recently added endoluminal fundoplication (ELF). The EsophyX2 is currently the most efficient device for endoluminal fundoplication. This device produces a partial, anterior valve, redesigning the antireflux barrier and the Hiss angle geometry, thus improving the activity of the lower esophageal sphincter (LES). This paper presents the operative technique, the patient selection criteria and published results. It has been shown that this technique is both secure, reproductible and effective in patients followed for 12-24 months: life-quality improvement, decreased acid exposure, suppression of antiacids, reduced hospitalization and recovery. Compared to antiacid therapy, ELF is far more effective and less invasive than laparoscopic fundoplication. For the moment we have no long-term results. ELF with EsophyX2 is a minimally invasive and efficient therapy for GERD that requires further evaluation. PMID:19886043

  6. [A simple biostatistical method for meta analysis of the data on 2 x 2 table].

    PubMed

    Liu, G; Wang, J; Kang, D; Hong, Q

    2000-06-01

    Meta-analysis is a method in common use for data analysis in evidence-based medicine. In this paper, based on the Mantel-Haenszel and Peto methods used for Meta-analysis of the data on 2 x 2 table, we put forward a simple calculating method for clinicians. It is useful for Meta-analysis and can be easily applied to analysis of the data from multi-studies in evidence-based medicine.

  7. Approximation of functions in L^{p(x)}_{2\\pi} by trigonometric polynomials

    NASA Astrophysics Data System (ADS)

    Sharapudinov, Idris I.

    2013-04-01

    We consider the Lebesgue space L^{p(x)}_{2\\pi} with variable exponent p(x). It consists of measurable functions f(x) for which the integral \\int_0^{2\\pi}\\vert f(x)\\vert^{p(x)}\\,dx exists. We establish an analogue of Jackson's first theorem in the case when the 2\\pi-periodic variable exponent p(x)\\ge1 satisfies the condition \\displaystyle \\vert p(x')-p(x'')\\vert\\ln\\frac{2\\pi}{\\vert x'-x''\\vert}=O(1),\\qquad x',x''\\in \\lbrack -\\pi,\\pi \\rbrack . Under the additional assumption p_- =\\min_x p(x)\\gt1 we also get an analogue of Jackson's second theorem. We establish an L^{p(x)}_{2\\pi}-analogue of Bernstein's estimate for the derivative of a trigonometric polynomial and use it to prove an inverse theorem for the analogues of the Lipschitz classes {Lip}(\\alpha,M)_{p(\\,\\cdot\\,)}\\subset L^{p(x)}_{2\\pi} for 0\\lt \\alpha\\lt 1. Thus we establish direct and inverse theorems of the theory of approximation by trigonometric polynomials in the classes {Lip}(\\alpha,M)_{p(\\,\\cdot\\,)}. In the definition of the modulus of continuity of a function f(x)\\in L^{p(x)}_{2\\pi}, we replace the ordinary shift f^h(x)=f(x+h) by an averaged shift determined by Steklov's function s_h(f)(x)=\\frac{1}{h}\\int_0^hf(x+t)\\,dt.

  8. Recurrent X-ray behaviour of the Z-source Cygnus X-2.

    NASA Astrophysics Data System (ADS)

    Kuulkers, E.; van der Klis, M.

    1996-02-01

    The authors analyzed the X-ray spectral variations of the low-mass X-ray binary Cyg X-2 on time scales longer than one day using EXOSAT data. They find evidence for the occurrence of three different types of behaviour which as their basic distinction have different X-ray brightness levels. Previously reported data from other X-ray satellites also show this behaviour.

  9. Entanglement monogamy inequality in a 2 x 2 x 4 system

    SciTech Connect

    Ren Xijun; Jiang Wei

    2010-02-15

    In this report, we show explicitly that the tangles of an arbitrary pure state in a 2 x 2 x 4 system satisfy the monogamy relation. This relation is also generalized to mixed states. As the tangle is always larger than the square of the concurrence, our result implies that the monogamy relation holds for concurrence too. It also supports the idea that the tangle could qualify as an elementary bipartite entanglement measure.

  10. 6. Credit WCT. Original 21" x 2Y" color negative is ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Credit WCT. Original 2-1" x 2-Y" color negative is housed in the JPL Photography Laboratory, Pasadena, California. JPL staff members Harold Anderson and John Morrow weigh out small amounts of an undetermined substance according to a solid propellant formula (JPL negative no. JPL-10277AC, 27 January 1989). - Jet Propulsion Laboratory Edwards Facility, Weigh & Control Building, Edwards Air Force Base, Boron, Kern County, CA

  11. Water adsorption on O(2x2)/Ru(0001) from STM experiments andfirst-principles calculations

    SciTech Connect

    Cabrera-Sanfelix, P.; Sanchez-Portal, D.; Mugarza, A.; Shimizu,T.K.; Salmeron, M.; Arnau, A.

    2007-10-15

    We present a combined theoretical and experimental study of water adsorption on Ru(0001) pre-covered with 0.25 monolayers (ML) of oxygen forming a (2 x 2) structure. Several structures were analyzed by means of Density Functional Theory calculations for which STM simulations were performed and compared with experimental data. Up to 0.25 monolayers the molecules bind to the exposed Ru atoms of the 2 x 2 unit cell via the lone pair orbitals. The molecular plane is almost parallel to the surface with its H atoms pointing towards the chemisorbed O atoms of the 2 x 2 unit cell forming hydrogen bonds. The existence of these additional hydrogen bonds increases the adsorption energy of the water molecule to approximately 616 meV, which is {approx}220 meV more stable than on the clean Ru(0001) surface with a similar configuration. The binding energy shows only a weak dependence on water coverage, with a shallow minimum for a row structure at 0.125 ML. This is consistent with the STM experiments that show a tendency of the molecules to form linear rows at intermediate coverage. Our calculations also suggest the possible formation of water dimers near 0.25 ML.

  12. Long-Term Evolution of Z-track in Cyg X-2

    NASA Astrophysics Data System (ADS)

    Boyd, P. T.; Smale, A. P.; Tripicco, M. J.

    2004-08-01

    The low-mass X-ray binary Z-source Cygnus X-2 displays a high amplitude, non-periodic long-term X-ray modulation with a timescale on the order of five to ten times its 9.8 day orbital period. The long-term modulation is often attributed to a warped, precessing accretion disk, however if this model is correct then the precession period is not stable. There are now (June 2004) just over 200 pointed RXTE observations of the Cyg X-2, spanning more than 3000 days. These observations cover fairly evenly the range of observed RXTE count rates (600-2400 counts/s/PCU). We use this collection of observations to investigate the evolution of the Z-shape in the color-color diagram and search for correlations with the long-term modulation. We also compare the time variability of the X-ray components of a common spectral model for Cyg X-2 with the long-term flux variability and the Z-shape evolution.

  13. The emission spectroscopy of the B2Σ- -X2 Π system of CD

    NASA Astrophysics Data System (ADS)

    Szajna, W.; Zachwieja, M.; Hakalla, R.

    2016-06-01

    The visible spectrum of CD has been investigated at high resolution between 24,500 and 27,500 cm-1 using a high accuracy dispersive optical spectroscopy technique. The CD molecules were produced and excited in a stainless steel hollow-cathode lamp with two anodes and filled with a mixture of He buffer gas and CD4. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. The 0-0, 1-0 and 1-1 bands of the B2Σ- -X2 Π transition have been registered and measured, while 2-0 and 2-1 absorption bands (Herzberg and Johns, 1969) have been reanalyzed. The current data were elaborated with help of recent X2 Π ground state parameters reported by Zachwieja et al. (2012) from investigation of the A2 Δ -X2 Π transition. This way, the improved spectroscopic constants for the B2Σ- state of CD have been provided as follows: νe = 26,050.787 (11) cm-1, ωe = 1653.019 (25) cm-1, ωexe = 123.899 (12) cm-1, Be = 7.08296 (32) cm-1, αe = 0.30741 (84) cm-1, and γe = - 0.10727 (42) cm-1.

  14. Examining Dual Meanings of Items in 2 x 2 Achievement Goal Questionnaires through MTMM Modeling and MDS Approach

    ERIC Educational Resources Information Center

    Wu, Chia-Huei; Chen, Lung Hung

    2010-01-01

    In 2001, Elliot and McGregor proposed a 2 x 2 (mastery-performance x approach- avoidance) achievement goal frameworks and developed a questionnaire to measure four goals (mastery-approach, mastery-avoidance, performance-approach, and performance-avoidance goals). This study examines the dual meanings of items in 2 x 2 achievement goal…

  15. Clinical evaluation of a 2K x 2K workstation for primary diagnosis in pediatric radiology

    NASA Astrophysics Data System (ADS)

    Razavi, Mahmood; Sayre, James W.; Simons, Margaret A.; Hamedaninia, Azar; Boechat, Maria I.; Hall, Theodore R.; Kangarloo, Hooshang; Taira, Ricky K.; Chuang, Keh-Shih; Kashifian, Payam

    1991-07-01

    Preliminary results of a large-scale ROC study evaluating the diagnostic performance of digital hardcopy film and 2K X 2K softcopy display for pediatric chest radiographs are presented. The pediatric disease categories studied were pneumothorax, linear atelectasis, air bronchograms, and interstitial disease. Digital images were obtained directly from a computed radiography system. Results from the readings of 239 chest radiographs by 4 radiologists show no significant difference between viewing images on film and softcopy display for the disease categories pneumothorax and air bronchograms. A slight performance edge for softcopy was seen for the disease categories of interstitial disease and linear atelectasis.

  16. Vibrational energy transfer in OH X 2Pi(i), v = 2 and 1

    NASA Technical Reports Server (NTRS)

    Raiche, George A.; Jeffries, Jay B.; Rensberger, Karen J.; Crosley, David R.

    1990-01-01

    Using an IR-pump/UV-probe method in a flow discharge cell, vibrational energy transfer in OH X 2Pi(i) has been studied. OH is prepared in v = 2 by overtone excitation, and the time evolution of population in v = 2 and 1 monitored by laser-induced fluorescence. Rate constants for vibrational relaxation by the colliders H2O, NH3, CO2, and CH4 were measured. Ratios of rate constants for removal from the two states, k2/k1, range from two to five.

  17. Credit WCT. Original 21" x 2A" color negative is housed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit WCT. Original 2-1" x 2-A" color negative is housed in the JPL Photography Laboratory, Pasadena, California. The mixing pot of the 150-gallon (Size 16-PVM) Baker-Perkins vertical mixer appears in its lowered position, exposing the mixer paddles. JPL employees Harold "Andy" Anderson and Ron Wright in protective clothing demonstrate how to scrape mixed propellant from mixer blades (JPL negative JPL10284BC, 27 January 1989) - Jet Propulsion Laboratory Edwards Facility, Mixer, Edwards Air Force Base, Boron, Kern County, CA

  18. Operating manual holographic interferometry system for 2 x 2 foot transonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Craig, J. E.

    1981-01-01

    A holographic interferometer system was installed in a 2X2 foot transonic wind tunnel. The system incorporates a modern, 10 pps, Nd:YAG pulsed laser which provides reliable operation and is easy to align. The spatial filtering requirements of the unstable resonator beam are described as well as the integration of the system into the existing Schieren system. A two plate holographic interferometer is used to reconstruct flow field data. For static wind tunnel models the single exposure holograms are recorded in the usual manner; however, for dynamic models such as oscillating airfoils, synchronous laser hologram recording is used.

  19. Kinetics of CH(X 2Pi) radical reactions with cyclopropane, cyclopentane, and cyclohexane

    NASA Technical Reports Server (NTRS)

    Zabarnick, S.; Fleming, J. W.; Lin, M. C.

    1988-01-01

    Rate constants have been obtained for CH(X 2Pi) radical reactions with cyclopropane, cyclopentane, and cyclohexane in order to establish the rate of CH insertion into secondary C-H bonds in alkanes. Data indicate that there is no measurable dependence on photolysis laser energy. The reactions all exhibited rate constants that decrease with increasing temperature. It is suggested that a possible set of pathways for the cycloalkane reactions is a ring-opening process where the excited adduct decomposes to a hydrogen atom and a diene.

  20. The rms-flux relations in different branches in Cyg X-2

    NASA Astrophysics Data System (ADS)

    Li, Z. B.; Song, L. M.; Qu, J. L.; Lei, Y. J.; Nie, J. Y.; Zhang, C. M.

    2012-10-01

    In this paper, the rms-flux (root mean square-flux) relation along the Z-track of the bright Z-Source Cyg X-2 is analyzed using the observational data of Rossi X-ray Timing Explorer (RXTE). Three types of rms-flux relations, i.e. positive, negative, and `arch'-like correlations are found in different branches. The rms is positively correlated with flux in normal branch (NB), but anti-correlated in the vertical horizontal branch (VHB). The rms-flux relation shows an `arch'-like shape in the horizontal branch (HB). We also try to explain this phenomenon using existing models.

  1. Credit WCT. Original 2Y4" x 2Y4" color negative is housed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit WCT. Original 2-Y4" x 2-Y4" color negative is housed in the JPL Photography Laboratory, Pasadena, California. JPL staff members Harold Anderson and John Morrow cast grain from the 1-gallon BakerPerkins model 4-PU mixer. A 1-pint Baker-Perkins model 2-PX mixer stands to the left in this view (JPL negative no. JPL-10295BC, 27 January 1989) - Jet Propulsion Laboratory Edwards Facility, Mixer & Casting Building, Edwards Air Force Base, Boron, Kern County, CA

  2. Credit WCT. Original 2A" x 2M" color negative is housed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit WCT. Original 2-A" x 2-M" color negative is housed in the JPL Photography Laboratory, Pasadena, California. Photo shows John Morrow in charge of milling operations on coupons ("dogbones") of propellant on an Index milling machine. Coupons were milled to precise dimensions for tensile tests. Note that two sprinkler heads have been placed in very close proximity to the milling table for fire suppression purposes (JPL negative no. JPL-10283AC, 27 January 1989) - Jet Propulsion Laboratory Edwards Facility, Preparation Building, Edwards Air Force Base, Boron, Kern County, CA

  3. Horizontal flows concurrent with an X2.2 flare in the active region NOAA 11158

    NASA Astrophysics Data System (ADS)

    Beauregard, L.; Verma, M.; Denker, C.

    2012-02-01

    Horizontal proper motions were measured with local correlation tracking (LCT) techniques in active region NOAA 11158 on 2011 February 15 at a time when a major (X2.2) solar flare occurred. The measurements are based on continuum images and magnetograms of the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. The observed shear flows along the polarity inversion line were rather weak (a few 100 m s-1). The counter-streaming region shifted toward the north after the flare. A small circular area with flow speeds of up to 1.2 km s-1 appeared after the flare near a region of rapid penumbral decay. The LCT signal in this region was provided by small-scale photospheric brigthenings, which were associated with fast traveling moving magnetic features. Umbral strengthening and rapid penumbral decay was observed after the flare. Both phenomena were closely tied to kernels of white-light flare emission. The white-light flare only lasted for about 15 min and peaked 4 min earlier than the X-ray flux. In comparison to other major flares, the X2.2 flare in active region NOAA 11158 only produced diminutive photospheric signatures.

  4. DYNAMICAL MASS CONSTRAINTS ON THE ULTRALUMINOUS X-RAY SOURCE NGC 1313 X-2

    SciTech Connect

    Liu Jifeng; Orosz, Jerome; Bregman, Joel N.

    2012-01-20

    Dynamical mass measurements hold the key to answering whether ultraluminous X-ray sources (ULXs) are intermediate-mass black holes (IMBHs) or stellar-mass black holes with special radiation mechanisms. NGC 1313 X-2 is so far the only ULX with Hubble Space Telescope light curves, the orbital period, and the black hole's radial velocity amplitude based on the He II {lambda}4686 disk emission line shift of {approx}200 km s{sup -1}. We constrain its black hole mass and other parameters by fitting observations to a binary light curve code with accommodations for X-ray heating of the accretion disk and the secondary. Given the dynamical constraints from the observed light curves and the black hole radial motion and the observed stellar environment age, the only acceptable models are those with 40-50 Myr old intermediate-mass secondaries in their helium core and hydrogen shell burning phase filling 40%-80% of their Roche lobes. The black hole can be a massive black hole of a few tens of M{sub Sun} that can be produced from stellar evolution of low-metallicity stars, or an IMBH of a few hundred to above 1000 M{sub Sun} if its true radial velocity 2K' < 40 km s{sup -1}. Further observations are required to better measure the black hole radial motion and the light curves in order to determine whether NGC 1313 X-2 is a stellar-mass black hole or an IMBH.

  5. Design of a quasi-2D photonic crystal optomechanical cavity with tunable, large x^2-coupling

    NASA Astrophysics Data System (ADS)

    Kalaee, M.; Paraïso, T. K.; Pfeifer, H.; Painter, O.

    2016-09-01

    We present the optical and mechanical design of a mechanically compliant quasi-two-dimensional photonic crystal cavity formed from thin-film silicon in which a pair of linear nanoscale slots are used to create two coupled high-$Q$ optical resonances. The optical cavity supermodes, whose frequencies are designed to lie in the $1500$~nm wavelength band, are shown to interact strongly with mechanical resonances of the structure whose frequencies range from a few MHz to a few GHz. Depending upon the symmetry of the mechanical modes and the symmetry of the slot sizes, we show that the optomechanical coupling between the optical supermodes can be either linear or quadratic in the mechanical displacement amplitude. Tuning of the nanoscale slot size is also shown to adjust the magnitude and sign of the cavity supermode splitting $2J$, enabling near-resonant motional scattering between the two optical supermodes and greatly enhancing the $x^2$-coupling strength. Specifically, for the fundamental flexural mode of the central nanobeam of the structure at $10$~MHz the per-phonon linear cross-mode coupling rate is calculated to be $\\tilde{g}_{+-}/2\\pi = 1$~MHz, corresponding to a per-phonon $x^2$-coupling rate of $\\tilde{g}'/2\\pi=1$~kHz for a mode splitting $2J/2\\pi = 1$~GHz which is greater than the radiation-limited supermode linewidths.

  6. Adsorption of water on O(2x2)/Ru(0001): thermal stability and inhibition of dissociation by H2O-O bonding

    SciTech Connect

    Mugarza, Aitor; Shimizu, Tomoko; Cabrera-Sanfelix, Pepa; Sanchez-Portal, Daniel; Arnau, Andres; Salmeron, Miquel

    2008-08-01

    The effect of preadsorbed oxygen on the subsequent adsorption and reactions of water on Ru(0001) has been studied using low temperature scanning tunneling microscopy and DFT calculations. Experiments were carried out for O coverages close to 0.25 ML. It was found that no dissociation of water takes place up to the desorption temperature of {approx}180-230 K. DFT calculations show that intact water on O(2x2)/Ru(0001) is {approx} 0.49 eV more stable than the dissociation products, H and OH, at their preferred fcc and top adsorption sites.

  7. Discovery of the Red-Skewed K-alpha Iron Line in Cyg X-2 with Suzaku

    NASA Technical Reports Server (NTRS)

    Shaposhnikov, Nikolai; Titarchuk, Lev; Laurent, Philippe

    2008-01-01

    We report on the Suzaku observation of neutron star low-mass X-ray binary Cygnus X-2 which reveals strong iron K-alpha emission line. The line profile shows a prominent red wing extending down to 4 keV. This discovery increases the number of neutron star sources where red-skewed iron lines were observed and strongly suggests that this phenomenon is common not only in black holes but also in other types of compact objects. We examine the line profile by fitting it with the model which attributes its production to the relativistic effects due to disk reflection of X-ray radiation. We also apply an alternative model where the red wing is a result of down-scattering effect of the first order with respect to electron velocity in the wind outflow. Both models describe adequately the observed line profile. However, the X-ray variability in a state similar to that in the Suzaku observation which we establish by analysing RXTE observation favors the wind origin of the line formation.

  8. Endurance and failure characteristics of modified Vasco X-2, CBS 600 and AISI 9310 spur gears. [aircraft construction materials

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Zaretsky, E. V.

    1980-01-01

    Gear endurance tests and rolling-element fatigue tests were conducted to compare the performance of spur gears made from AISI 9310, CBS 600 and modified Vasco X-2 and to compare the pitting fatigue lives of these three materials. Gears manufactured from CBS 600 exhibited lives longer than those manufactured from AISI 9310. However, rolling-element fatigue tests resulted in statistically equivalent lives. Modified Vasco X-2 exhibited statistically equivalent lives to AISI 9310. CBS 600 and modified Vasco X-2 gears exhibited the potential of tooth fracture occurring at a tooth surface fatigue pit. Case carburization of all gear surfaces for the modified Vasco X-2 gears results in fracture at the tips of the gears.

  9. Exploring water binding motifs to an excess electron via X2(-)(H2O) [X = O, F].

    PubMed

    Chiou, Mong-Feng; Sheu, Wen-Shyan

    2012-07-26

    X(2)(-)(H(2)O) [X = O, F] is utilized to explore water binding motifs to an excess electron via ab initio calculations at the MP4(SDQ)/aug-cc-pVDZ + diffs(2s2p,2s2p) level of theory. X(2)(-)(H(2)O) can be regarded as a water molecule that binds to an excess electron, the distribution of which is gauged by X(2). By varying the interatomic distance of X(2), r(X1-X2), the distribution of the excess electron is altered, and the water binding motifs to the excess electron is then examined. Depending on r(X1-X2), both binding motifs of C(s) and C(2v) forms are found with a critical distance of ∼1.37 Å and ∼1.71 Å for O(2)(-)(H(2)O) and F(2)(-)(H(2)O), respectively. The energetic and geometrical features of O(2)(-)(H(2)O) and F(2)(-)(H(2)O) are compared. In addition, various electronic properties of X(2)(-)(H(2)O) are examined. For both O(2)(-)(H(2)O) and F(2)(-)(H(2)O), the C(s) binding motif appears to prevail at a compact distribution of the excess electron. However, when the electron is diffuse, characterized by the radius of gyration in the direction of the X(2) bond axis with a threshold of ∼0.84 Å, the C(2v) binding motif is formed.

  10. Credit WCT. Original 2¾" x 2Y4" color negative is housed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit WCT. Original 2-¾" x 2-Y4" color negative is housed in the JPL Photography Laboratory, Pasadena, California. View shows JPL staff member John Morrow loading the grinder hopper. The hopper has a 10 mesh screen to filter out particles too large for the mill. Oxidizer is passed steadily to the hammers by a stainless steel feed screw. Oxidizer may be passed through the mill several times depending on the fineness required by a given propellant formula; the maximum charge is 130 pounds (59.0 Kg). The drum below the mill has an electrically conductive plastic liner which receives the ground oxidizer (JPL negative no. JPL10279AC, 27 January 1989) - Jet Propulsion Laboratory Edwards Facility, Oxidizer Grinder Building, Edwards Air Force Base, Boron, Kern County, CA

  11. Propeller effect in action in the ultraluminous accreting magnetar M82 X-2

    NASA Astrophysics Data System (ADS)

    Tsygankov, Sergey S.; Mushtukov, Alexander A.; Suleimanov, Valery F.; Poutanen, Juri

    2016-03-01

    We present here the first convincing observational manifestation of a magnetar-like magnetic field in an accreting neutron star in binary system - the first pulsating ultraluminous X-ray source X-2 in the galaxy M82. Using the Chandra X-ray observatory data, we show that the source exhibit the bimodal distribution of the luminosity with two well-defined peaks separated by a factor of 40. This behaviour can be interpreted as the action of the `propeller regime' of accretion. The onset of the propeller in a 1.37 s pulsar at luminosity of ˜1040 erg s-1 implies the dipole component of the neutron star magnetic field of ˜1014 G.

  12. The broad-band X-ray spectrum of Cygnus X-2

    NASA Technical Reports Server (NTRS)

    Pravdo, S. H.

    1983-01-01

    Cygnus X-2 was observed with the broad-band X-ray spectroscopy experiment, HEAO 1 A-2, in the energy range 0.4-18 keV for four intervals of approximately 31 s over the course of 5 days in 1977. The spectra can be adequately represented by single-temperature thermal bremmstrahlung continua with temperatures ranging from 3.7 x 10 to the 7th K to 6.4 x 10 to the 7th K. An examination of the spectra and the spectra-luminosity relationship effectively rules out one degenerate dwarf model for the X-ray emission. The far-UV continuum emission could be dominated by this continuum component during X-ray high states, an effect which would be detected in optical UV line observations. A Comptonized X-ray cloud around a neutron star remains a viable model for the observed X-ray spectra.

  13. Accretion mode of the ultraluminous X-ray source M82 X-2

    NASA Astrophysics Data System (ADS)

    Karino, S.; Miller, J. C.

    2016-11-01

    Periodic pulsations have been found in emission from the ultraluminous X-ray source M82 X-2, strongly suggesting that the emitter is a rotating neutron star rather than a black hole. However, the radiation mechanisms and accretion mode involved have not yet been clearly established. In this paper, we examine the applicability to this object of standard accretion modes for high mass X-ray binaries (HMXBs). We find that spherical wind accretion, which drives OB-type HMXBs, cannot apply here but that there is a natural explanation in terms of an extension of the picture for standard Be-type HMXBs. We show that a neutron star with a moderately strong magnetic field, accreting from a disc-shaped wind emitted by a Be-companion, could be compatible with the observed relation between spin and orbital period. A Roche lobe overflow picture is also possible under certain conditions.

  14. Multifrequency observations of CYG X-2: X ray observations with GINGA

    NASA Astrophysics Data System (ADS)

    Hasinger, Guenther; van der Klis, M.; Ebisawa, K.; Dotani, T.; Mitsuda, K.

    1989-10-01

    The observations of the bright low-mass x ray binary and Z-source Cyg X-2, carried out with the Japanese x ray satellite Ginga, are reported. The observations were effectuated for six days in 1988 June and October at x ray, ultraviolet, optical and radio wavelengths. On both occasions all three spectral states, the horizontal, normal and flaring branch, showing up as a Z-shaped correlation curve in an x ray color-color diagram, were observed. Quasi-Periodic Oscillations (QPO) and noise are detected. The sudden disappearance of the radio flares, hand in hand with the decrease of QPO and noise power and the softening of the x ray spectra at the transition from horizontal branch to normal branch can be interpreted in terms of a sudden inflation of the inner disk, which engulfs the entire magnetosphere in the normal branch.

  15. Network Offoaded Hierarchical Collectives Using ConnectX-2's CORE-Direct Capabilities

    SciTech Connect

    Rabinovitz, Ishai; Shamis, Pavel; Graham, Richard L; Bloch, Noam; Shainer, Gilad

    2010-01-01

    As the scale of High Performance Computing (HPC) systems continues to increase, demanding that we extract even more parallelism from applications, the need to move communication management away from the Central Processing Unit (CPU) becomes even greater. Moving this management to the network, frees up CPU cycles for computation, making it possible to overlap computation and communication. In this paper we continue to investigate how to best use the new CORE-Direct support added in the ConnectX-2 Host Channel Adapter (HCA) for creating high performance, asynchronous collective operations that are managed by the HCA. Specifically we consider the network topology, creating a two-level communication hierarchy, reducing the MPI Barrier completion time by 45%, from 26.59 microseconds, when not considering network topology, to 14.72 microseconds, with the CPU based collective barrier operation completing in 19.04 microseconds. The nonblocking barrier algorithm has similar performance, with about 50% of that time available for computation.

  16. Properties of (Ga1-x In x )2O3 over the whole x range

    NASA Astrophysics Data System (ADS)

    Maccioni, M. B.; Ricci, F.; Fiorentini, V.

    2016-06-01

    Using density-functional ab initio theoretical techniques, we study (Ga1-x In x )2O3 in both its equilibrium structures (monoclinic β and bixbyite) and over the whole range of composition. We establish that the alloy exhibits a large and temperature-independent miscibility gap. On the low-x side, the favored phase is isostructural with β -Ga2O3; on the high-x side, it is isostructural with bixbyite In2O3. The miscibility gap opens between approximately 15% and 55% In content for the bixbyite alloy grown epitaxially on In2O3, and 15% and 85% In content for the free-standing bixbyite alloy. The gap, volume and band offsets to the parent compound also exhibit anomalies as function of x. Specifically, the offsets in epitaxial conditions are predominantly type-B staggered, but have opposite signs in the two end-of-range phases.

  17. The A2Δ-X2Π band system of the CD radical

    NASA Astrophysics Data System (ADS)

    Zachwieja, Mirosław; Szajna, Wojciech; Hakalla, Rafał

    2012-05-01

    The A2Δ-X2Π, Δv = 0 sequence of the CD radical was observed in the 22 800-24 000 cm-1 spectral region using a conventional spectroscopic technique. The CD molecules were formed and excited in a stainless steel hollow-cathode lamp with two anodes and filled with a mixture of He buffer gas and CD4. The emission from the discharge was observed with a plane-grating spectrograph and recorded using a photomultiplier tube. The observed lines were assigned to the 0-0, 1-1, 2-2, and 3-3 bands. In total, 1189 transition wavenumbers were precisely measured, with an estimated accuracy of 0.003 cm-1, and rotationally analyzed. In the final global fit, the present data were combined with available high-resolution measurements of the vibration-rotation transitions [Morino et al., J. Mol. Spectrosc. 174 (1995) 123-131] and pure rotational transitions [Brown and Evenson, J. Mol. Spectrosc. 136 (1989) 68-85; Halfen et al., Astrophys. J. 687 (2008) 731-736]. This procedure enabled the extraction of molecular constants for the A2Δ and X2Π states of CD. The equilibrium parameters were compared with the calculations performed using the Born-Oppenheimer approximation, and a slight difference was observed in some cases due to the partial breakdown of the B-O approximation. The electronic isotopic shift, Δνe, for the A-X transition was determined to be 32.105 cm, and the shift independent of the nuclear mass coefficient, ΔU=64.762(38) cm, was also calculated.

  18. Development of a 2K x 2K GaAs QWIP Focal Plane Array

    NASA Technical Reports Server (NTRS)

    Jhabvala, M.; Choi, K.; Jhabvala, C.; Kelly, D.; Hess, L.; Ewin, A.; La, A.; Wacynski, A.; Sun, J.; Adachi, T.; Costen, N.; Ni, Q.; Snodgrass, Stephen; Foltz, Roger

    2013-01-01

    We are developing the next generation of GaAs Quantum Well Infrared Photodetector (QWIP) focal plane arrays (FPAs) in preparation for future NASA space-borne Earth observing missions. It is anticipated that these missions will require both wider ground spatial coverage as well as higher ground imaging resolution. In order to demonstrate our capability in meeting these future goals we have taken a two-tiered approach in the next stage of advanced QWIP focal plane array development. We will describe our progress in the development of a 512 x 3,200 (512 x 3K) array format for this next generation thermal imaging array for the NASA Landsat project. However, there currently is no existing readout integrated circuit (ROIC) for this format array.so to demonstrate the ability to scale-up an existing ROIC we developed a 1,920 x 2,048 (2K x 2K) array and it hybridized to a Raytheon SB419 CTIA readout integrated circuit that was scaled up from their existing 512 x 640 SB339 ROIC. Two versions of the 512 x 3K QWIP array were fabricated to accommodate a future design scale-up of both the Indigo 9803 ROIC based on a 25 micron pixel dimension and a scale up of the Indigo 9705 ROIC based on a 30 micron pixel dimension. Neither readout for the 512 x 3K has yet to be developed but we have fabricated both versions of the array. We describe the design, development and test results of this effort as well as the specific applications these FPAs are intended to address.

  19. Laser-induced fluorescence of CN/X2 Sigma +/ produced by photolysis of C2N2 at 160 nm

    NASA Technical Reports Server (NTRS)

    Cody, R. J.; Sabety-Dzvonik, M. J.; Jackson, W. M.

    1977-01-01

    The paper reports laser-induced fluorescence measurements of the initial product state distributions of CN(X2 Sigma +) produced during the photolysis of C2N2 at a wavelength of 160 nm. The parent molecules were photodissociated by an argon flash lamp, and saturated solutions of BBD in p-dioxane were used as a laser dye to produce radiation that excited CN radicals in the (upsilon-double-prime, N-prime) vibrational-rotational sublevels of the X state to the B-state sublevels. Spectral-line identification is discussed along with the observed rotational, electronic, and vibrational energy partitionings. The effect of added buffer gas (N2 or He) on the observed product state distributions is examined in order to monitor collisional energy transfer from CN(A2 Pi, upsilon = 0) to CN(X2 Sigma +, upsilon-double-prime = 4). It is found that both buffer gases produce population inversion between the upsilon-double-prime = 4 and upsilon-double-prime = 3 levels of the X state.

  20. SU-E-I-86: Evaluation of the New RaySafe Unfors X2 Dosimetry System

    SciTech Connect

    Heintz, P; Chambers, G; Sandoval, D

    2014-06-01

    Purpose: To evaluate the new RaySafe Unfors X2 (X2) dosimetry system and compare it to the operation of the RaySafe Unfors Xi (Xi) and Radcal Accugold (RCAG) dosimetry systems. The comparison was done for the radiographic/fluoroscopic detectors, mammography detectors and the CT ionization chambers. Methods: This study used several R/F rooms, GE AMX4 portable x-ray unit, Siemens Biograph 16 slice CT scanner and a Hologic Dimensions mammography unit to evaluate the dosimetry systems. The three X2 detectors were compared to similar detectors of the older Xi and RCAG detectors under clinical conditions used for diagnostic medical physics testing. Measurements of kVp, HVL and exposure were made under identical conditions. Results: For radiography and fluoroscopy the three systems agreed to within +2 kVp in the 60 to 140 kVp range, HVL measurements agreed to within +2 mm Al and the exposures agreed to within +5%. The RCAG 6 cc ionization chamber measured at least 3% higher than the diode systems. The X2 R/F detector appeared to be transparent to the fluoroscopy AEC system. For exposures made using both the CT ACR dose phantoms, the X2 agreed to within +3% of the other two systems. For mammography measurements, the three systems agreed to within +0.4kVp (25-49 kVp range), HVL measurements agreed to within +0.05 mm Al and the exposures agreed to within +1% of the ionization chamber. Conclusion: The X2 system is a new version of the older Xi system. The system is faster, more robust, very easy to use, has a larger dynamic range, produced less errors and stores 1000 exposures. The measurements showed that the system performs well in the clinical environment and the X2 is within + 5% agreement of the other two calibrated systems.

  1. P2X2 and P2X5 Receptors Mediate Bladder Hyperesthesia in ICC in Female Overactive Bladder.

    PubMed

    Meng, Mingsen; Zheng, Ji; Yan, Junan; Li, Qianwei; Fang, Qiang; Li, Weibing

    2015-06-01

    This study was set to explore the role of P2X2 and P2X5 as the important molecules in sensory afferent of bladder in female overactive bladder (OAB) patients with the bladder hyperesthesia. Sixty-eight OAB patients admitted in Southwest Hospital affiliated to the Third Military Medical University during September, 2011-December, 2012 were selected and included in the experimental group (OAB group) and 30 healthy volunteers during the same period were included as the control group. We recorded voiding diary and urodynamic results, and immunohistochemistry analysis was used to detect P2X2 and P2X5 receptor in interstitial cell of Caja (ICC) in bladder tissue of female OAB patients and healthy volunteers, to tentatively explore the effect of P2X2 and P2X5 in bladder hyperesthesia. Urodynamic study has important diagnostic value in the diagnosis and differential diagnosis of OAB. P2X2 receptor was significantly up-regulated in bladder ICC in OAB group. The blockage of P2X2 receptor could significantly inhibit the contraction of bladder muscle strips, decrease the bladder pressure and the electric discharge of pelvic nerve. PET and urodynamic study showed that micturition desire sense in PAG area of pons in OAB patients was significantly increased compared with the control group. The up-regulation of P2X2 in ICC is an important factor to cause bladder hyperesthesia in OAB patients. PET and urodynamic study indicate that the bladder-originated nervous impulses are important cause of OAB. This study provides a basis for the study of P2X2 receptor in ICC in bladder hyperesthesia of OAB patients.

  2. Initiation of a passivated interface between hafnium oxide and In(Ga)As(0 0 1)-(4x2).

    PubMed

    Clemens, Jonathon B; Bishop, Sarah R; Lee, Joon Sung; Kummel, Andrew C; Droopad, Ravi

    2010-06-28

    Hafnium oxide interfaces were studied on two related group III rich semiconductor surfaces, InAs(0 0 1)-(4x2) and In(0.53)Ga(0.47)As(0 0 1)-(4x2), via two different methods: reactive oxidation of deposited Hf metal and electron beam deposition of HfO(2). The interfaces were investigated with scanning tunneling microscopy and spectroscopy (STS). Single Hf atom chemisorption sites were identified that are resistant to oxidation by O(2), but Hf islands are reactive to O(2). After e(-) beam deposition of <1 ML of HfO(2), single chemisorption sites were identified. At low coverage (<1 ML), the n-type and p-type HfO(2)/InGaAs(0 0 1)-(4x2) interfaces show p-type character in STS, which is typical of clean InGaAs(0 0 1)-(4x2). After annealing below 200 degrees C, full coverage HfO(2)/InGaAs(0 0 1)-(4x2) (1-3 ML) has the surface Fermi level shifted toward the conduction band minimum for n-type InGaAs, but near the valence band maximum for p-type InGaAs. This is consistent with the HfO(2)/InGaAs(0 0 1)-(4x2) interface being at least partially unpinned, i.e., a low density of states in the band gap. The partially unpinned interface results from the modest strength of the bonding between HfO(2) and InGaAs(0 0 1)-(4x2) that prevents substrate atom disruption. The fortuitous structure of HfO(2) on InAs(0 0 1)-(4x2) and InGaAs(0 0 1)-(4x2) allows for the elimination of the partially filled dangling bonds on the surface, which are usually responsible for Fermi level pinning.

  3. Initiation of a passivated interface between hafnium oxide and In(Ga)As(0 0 1)-(4x2)

    SciTech Connect

    Clemens, Jonathon B.; Bishop, Sarah R.; Kummel, Andrew C.; Lee, Joon Sung

    2010-06-28

    Hafnium oxide interfaces were studied on two related group III rich semiconductor surfaces, InAs(0 0 1)-(4x2) and In{sub 0.53}Ga{sub 0.47}As(0 0 1)-(4x2), via two different methods: reactive oxidation of deposited Hf metal and electron beam deposition of HfO{sub 2}. The interfaces were investigated with scanning tunneling microscopy and spectroscopy (STS). Single Hf atom chemisorption sites were identified that are resistant to oxidation by O{sub 2}, but Hf islands are reactive to O{sub 2}. After e{sup -} beam deposition of <<1 ML of HfO{sub 2}, single chemisorption sites were identified. At low coverage (<1 ML), the n-type and p-type HfO{sub 2}/InGaAs(0 0 1)-(4x2) interfaces show p-type character in STS, which is typical of clean InGaAs(0 0 1)-(4x2). After annealing below 200 deg. C, full coverage HfO{sub 2}/InGaAs(0 0 1)-(4x2) (1-3 ML) has the surface Fermi level shifted toward the conduction band minimum for n-type InGaAs, but near the valence band maximum for p-type InGaAs. This is consistent with the HfO{sub 2}/InGaAs(0 0 1)-(4x2) interface being at least partially unpinned, i.e., a low density of states in the band gap. The partially unpinned interface results from the modest strength of the bonding between HfO{sub 2} and InGaAs(0 0 1)-(4x2) that prevents substrate atom disruption. The fortuitous structure of HfO{sub 2} on InAs(0 0 1)-(4x2) and InGaAs(0 0 1)-(4x2) allows for the elimination of the partially filled dangling bonds on the surface, which are usually responsible for Fermi level pinning.

  4. Carrier transport in the V[TCNE]x (TCNE = tetracyanoethylene; x ~ 2) organic-based magnet.

    PubMed

    Pokhodnya, Konstantin; Bonner, Michael; Prigodin, Vladimir; Epstein, Arthur J; Miller, Joel S

    2013-05-15

    The carrier transport of chemical vapor deposition (CVD) prepared films of the room temperature organic-based magnet V[TCNE]x (TCNE = tetracyanoethylene; x ~ 2) over a broad temperature and magnetic field range is reported. Due to disorder the [TCNE](·-) sites are located in statistically different environments, and their energies vary from site-to-site, which leads to tailing the density of states into the energy gap, creating electronic traps and suppressing the electron mobility. Conversely, these variations have little effect on the valence band derived from the octahedral V(II)3d(t(2g)) levels, and, hence, on the hole mobility. Presuming a Gaussian distribution of the energies of the localized states in the gap, a model that adequately describes the experimental data is proposed. In this model the T(-1) temperature dependent term was added to the Arrhenius activation energy, Ea, which effectively describes its decrease on cooling. The linear increase of positive magnetoresistance with magnetic field, as well as its weak temperature dependence [ is proportional to (1-T/Tc)(-1/2)] is discussed in terms of a small contribution to Ea associated with the change of magnetic energy. PMID:23604366

  5. Overlapping Computation and Communication: Barrier Algorithms and ConnectX-2 CORE-Direct Capabilities

    SciTech Connect

    Graham, Richard L; Poole, Stephen W; Shamis, Pavel; Bloch, Gil; Bloch, Noam; Kagan, Michael; Rabinovitz, Ishai; Shainer, Gilad

    2010-01-01

    This paper explores the computation and communication overlap capabilities enabled by the new CORE-Direct hardware capabilities introduced in the InfiniBand (IB) Host Channel Adapter (HCA) ConnectX-2. These capabilities enable the progression and completion of data-dependent communications sequences to progress and complete at the network level without any Central Processing Unit (CPU) involvement. We use the latency dominated nonblocking barrier algorithm in this study, and find that at 64 process count, a contiguous time slot of about 80 percent of the nonblocking barrier time is available for computation. This time slot increases as the number of processes participating increases. In contrast, CPU based implementations provide a time slot of up to 30 percent of the nonblocking barrier time. This bodes well for the scalability of simulations employing offloaded collective operations. These capabilities can be used to reduce the effects of system noise, and when using nonblocking collective operations have the potential to hide the effects of application load imbalance.

  6. Overlapping Computation and Communication: Barrier Algorithms and ConnectX-2 CORE-Direct Capabilities

    SciTech Connect

    Graham, Richard L; Poole, Stephen W; Shamis, Pavel; Bloch, Gil; Bloch, Noam; Shainer, Gilad

    2010-01-01

    This paper explores the computation and communication overlap capabilities enabled by the new CORE-Direct hardware capabilities introduced in the InfiniBand (IB) Host Channel Adapter (HCA) ConnectX-2. These capabilities enable the progression and completion of data-dependent communications sequences to progress and complete at the network level without any Central Processing Unit (CPU) involvement. We use the latency dominated nonblocking barrier algorithm in this study, and find that at 64 process count, a contiguous time slot of about 80 percent of the nonblocking barrier time is available for computation. This time slot increases as the number of processes participating increases. In contrast, CPU based implementations provide a time slot of up to 30 percent of the nonblocking barrier time. This bodes well for the scalability of simulations employing offloaded collective operations These capabilities can be used to reduce the effects of system noise, and when using nonblocking collective operations have the potential to hide the effects of application load imbalance.

  7. Chemical abundances in the secondary star of the X-ray binary Cygnus X-2

    NASA Astrophysics Data System (ADS)

    Suárez-Andrés, l.; González Hernández, J. I.; Israelian, G.; Rebolo, R.

    2015-05-01

    Spectroscopic data of low-mass X-ray binaries (LMXB) can provide valuable information on supernova properties. In these systems the companion star is probably close enough to be polluted by some of the matter ejected during the supernova (SN) event of the progenitor of the compact object. We present high-resolution spectra, acquired with UES@WHT, of the LMXB Cygnus X-2. We derive the stellar parameters of the companion, taking into account any possible veiling from the accretion disk surrounding the NS. We have studied the chemical abundances, including α-elements and some Fe-peak elements to search for signatures of chemical anomalies that could have been imprinted on the secondary star in the SN event. We find a super-solar Fe content in the companion star, and an abundance enhancement in most of the studied elements. Our results suggest that the secondary star may have captured a significant amount of the ejected matter during the SN explosion. We explore different explosion models to explain these abundance anomalies.

  8. Line strengths of rovibrational and rotational transitions in the X2 Π ground state of OH

    NASA Astrophysics Data System (ADS)

    Brooke, James S. A.; Bernath, Peter F.; Western, Colin M.; Sneden, Christopher; Afşar, Melike; Li, Gang; Gordon, Iouli E.

    2016-01-01

    A new line list including positions and absolute transition strengths (in the form of Einstein A values and oscillator strengths) has been produced for the OH ground X2 Π state rovibrational (Meinel system) and pure rotational transitions. All possible transitions are included with v‧ and v ″ up to 13, and J up to between 9.5 and 59.5, depending on the band. An updated fit to determine molecular constants has been performed, which includes some new rotational data and a simultaneous fitting of all molecular constants. The absolute transition strengths are based on a new dipole moment function, which is a combination of two high level ab initio calculations. The calculations show good agreement with an experimental v = 1 lifetime, experimental μv values, and Δv=2 line intensity ratios from an observed spectrum. To achieve this good agreement, an alteration in the method of converting matrix elements from Hund's case (b) to (a) was made. Partitions sums have been calculated using the new energy levels, for the temperature range 5-6000 K, which extends the previously available (in HITRAN) 70-3000 K range. The resulting absolute transition strengths have been used to calculate O abundances in the Sun, Arcturus, and two red giants in the Galactic open and globular clusters M67 and M71. Literature data based mainly on [O I] lines are available for the Sun and Arcturus, and excellent agreement is found.

  9. Activation of trimeric P2X2 receptors by fewer than three ATP molecules.

    PubMed

    Stelmashenko, Olga; Lalo, Ulyana; Yang, Yue; Bragg, Laricia; North, R Alan; Compan, Vincent

    2012-10-01

    P2X receptors are trimeric membrane proteins. When they bind extracellular ATP, a conformational change occurs that opens a transmembrane ion channel. The ATP-binding pocket is formed in a cleft between two subunits, and a critical amino acid residue for ATP contact is Lys⁶⁹ (P2X2 numbering). In the present work, we sought to determine whether the binding of fewer than three ATP molecules could open the ion channel. We expressed eight concatenated cDNAs in human embryonic kidney cells, which encoded three serially joined, epitope-tagged, subunits with either Lys or Ala at position 69 (denoted as KKK, KKA, KAK, AKK, KAA, AKA, AAK, and AAA). Western blotting of surface-biotinylated proteins indicated that breakdown of concatemers to individual subunits was minimal. Recording of membrane currents in response to ATP (whole cell and excised outside-out patch) showed that all formed functional channels except AAK, AKA, and AAA. There was no difference in the kinetics of activation and deactivation among KKK, KKA, KAK, and AKK channels, and amplitude of the unitary conductances was in all cases not different from that found after expression of a single wild-type subunit. Currents through KKA and KAK receptors were larger than those observed for AKK receptors. The results indicate that trimeric P2X receptors containing only two intact binding sites can be readily activated by ATP.

  10. Inorganic selenium speciation in groundwaters by solid phase extraction on Dowex 1X2.

    PubMed

    Lin, Tser-Sheng

    2007-10-01

    A Dowex 1X2 resin separation technique followed by analysis with atomic absorption spectroscopy was evaluated for the study of inorganic selenium speciation in groundwaters. After Se(IV) and Se(VI) were retained on the resin column, Se(IV) and Se(VI) were eluted out by 0.1 and 1M nitric acid solutions. The method detection limit was 5.6 ng/L for both Se(IV) and Se(VI). Analysis of synthetic solutions consistently yielded more than 90% recovery of these two selenium forms with negligible cross-contamination. The results of spiked well waters show that this method can be applied at ultra-trace level of Se in groundwater and the interference of chloride ion can be neglected. Water samples collected from the monitoring wells in the Science-based Industrial Park, Hsin-Chu, Taiwan, were analyzed. Average dissolved selenium concentrations were 32.1+/-17.6 ng/L. The proportion of Se(VI) to the total dissolved selenium ranged from 47.6 to 61.2% and an average of 53.8% in water samples analyzed.

  11. Elucidating the Foundations of Statistical Inference with 2 x 2 Tables

    PubMed Central

    Choi, Leena; Blume, Jeffrey D.; Dupont, William D.

    2015-01-01

    To many, the foundations of statistical inference are cryptic and irrelevant to routine statistical practice. The analysis of 2 x 2 contingency tables, omnipresent in the scientific literature, is a case in point. Fisher's exact test is routinely used even though it has been fraught with controversy for over 70 years. The problem, not widely acknowledged, is that several different p-values can be associated with a single table, making scientific inference inconsistent. The root cause of this controversy lies in the table's origins and the manner in which nuisance parameters are eliminated. However, fundamental statistical principles (e.g., sufficiency, ancillarity, conditionality, and likelihood) can shed light on the controversy and guide our approach in using this test. In this paper, we use these fundamental principles to show how much information is lost when the tables origins are ignored and when various approaches are used to eliminate unknown nuisance parameters. We present novel likelihood contours to aid in the visualization of information loss and show that the information loss is often virtually non-existent. We find that problems arising from the discreteness of the sample space are exacerbated by p-value-based inference. Accordingly, methods that are less sensitive to this discreteness - likelihood ratios, posterior probabilities and mid-p-values - lead to more consistent inferences. PMID:25849515

  12. Heating in an Extended Accretion Disk Corona Along the Z-Pattern in Cyg X-2

    NASA Astrophysics Data System (ADS)

    Schulz, N. S.; Huenemoerder, D. P.; Ji, L.; Nowak, M.; Yao, Y.; Canizares, C. R.

    2009-02-01

    We observed at very high spectral resolution the prototype Z-source Cyg X-2 twice along its entire X-ray spectral variation pattern. In this preliminary analysis, we find an extended accretion disk corona (ADC) exhibiting Lyα emissions from various H-like ions, as well as emissions from He-like ions of Fe and Al, and Be-like ions of Fe. The brightest lines show a range of line broadening: H-like lines are very broad with Doppler velocities between 1100 and 2700 km s-1, while some others are narrower with widths of a few hundred km s-1. Line diagnostics allow us for the first time to determine coronal parameters. The line properties are consistent with a stationary, extended up to 1010 cm, dense (1 × 1015 cm-3), and hot (log ξ gsim 3; T gsim 106 K) ADC. We find ongoing heating of the corona along the Z-track and determine that heating luminosities change from about 0.4×L Edd on the horizontal to about 1.4 × L Edd on the flaring branch.

  13. Accretion Disk Coronal Heating Along The Z-pattern In Cygnus X-2

    NASA Astrophysics Data System (ADS)

    Schulz, Norbert S.; Huenemoerder, D. P.; Nowak, M.; Ji, L.; Yao, Y.; Canizares, C. R.

    2009-01-01

    Z-sources are low mass X-ray binaries containing accreting neutron stars which emit luminous X-rays near Eddington luminosities (L_Edd). Their X-ray spectra change in a systematic Z-shaped pattern from the horizontal (HB), to the normal (NB), and to the flaring branch (FB). Cyg X-2 is a prototype Z-source which we observed in X-rays twice along the entire X-ray spectral variation pattern at very high spectral resolution. We find a wealth of resolved and broad emission line features which we attribute to a hot accretion disk corona (ADC). The lines have Doppler velocities between 400 and 2700 km/s, which place the origin of emission within 10^10 cm of the accretion disk. We also find evidence for a flux evolution along the Z-pattern. The line emissivities indicate that the source luminosity changes from about 0.7 L_Edd in the HB to 2.6 L_Edd on the FB. The observed line flux evolution provides direct evidence for ongoing heating of the ADC along the spectral branches.

  14. Robust optimization of 2x2 multimode interference couplers with fabrication uncertainties

    NASA Astrophysics Data System (ADS)

    Rehman, Samee ur; Langelaar, Matthijs; Van Keulen, Fred

    2013-03-01

    In this paper, we propose a novel design-for-manufacture strategy for integrated photonics which specifically addresses the commonly encountered scenario in which probability distributions of the manufacturing variations are not available, however their bounds are known. The best design point for the device, in the presence of these uncertainties, can be found by applying robust optimization. This is performed by minimizing the maximum realizable value of the objective with respect to the uncertainty set so that an optimum is found whose performance is relatively immune to fabrication variations. Instead of applying robust optimization directly on a computationally expensive simulation model of the integrated photonic device, we construct a cheap surrogate model by uniformly sampling the simulated device at different values of the design variables and interpolating the resulting objective using a Kriging metamodel. By applying robust optimization on the constructed surrogate, the global robust optimum can be found at low computational cost. As an illustration of the method's general applicability, we apply the robust optimization approach on a 2x2 multimode interference (MMI) coupler. We robustly minimize the imbalance in the presence of uncertainties arising from variations in the fabricated design geometry. For this example device, we also study the influence of the number of sample points on the quality of the metamodel and on the robust optimization process.

  15. Statistical parameters for resource evaluation of geochemical data from the Ajo 1 degree x 2 degrees Quadrangle, Arizona

    USGS Publications Warehouse

    Theobald, P.K.; Barton, Harlan N.

    1983-01-01

    Statistical data are presented from a regional geochemical study of the Ajo 1? X 2? quadrangle exclusive of the Papago Indian Reservation, but including the extension of Organ Pipe Cactus National Monument into the Lukeville 1? X 2? quadrangle. Frequency distribution data from the analysis of stream-sediment and heavy-mineral-concentrate samples for 31 elements have broad ranges and for most elements have maxima well above normal. Elemental associations derived from correlation and R-mode factor analysis related to regional lithologic variation and for some associations suggest mineral-resource potential.

  16. Bioaugmentation of activated sludge with elemental sulfur producing strain Thiopseudomonas denitrificans X2 against nitrate shock load.

    PubMed

    Tan, Wenbo; Huang, Cong; Chen, Chuan; Liang, Bin; Wang, Aijie

    2016-11-01

    The sulfide and nitrogen compounds in wastewaters are toxic and cause a serious environmental problem. Thiopseudomonas denitrificans X2, which is the type species of a novel genus Thiopseudomonas was used for bioaugmentation. It oxidized sulfide and acetate with nitrate, and generated elemental sulfur that could be recovered as resource. The generation rate of elemental sulfur was enhanced significantly by the bioaugmentation under the condition of excessive nitrate feeding. The inoculums survived and worked actively in the activated sludge system as the dominant population. Thiopseudomonas denitrificans X2 could be applied to wastewater treatment and resource recovery simultaneously. PMID:27590576

  17. ConnectX2 In niBand Management Queues: New support for Network Of oaded

    SciTech Connect

    Graham, Richard L; Poole, Stephen W; Shamis, Pavel; Bloch, Gil; Bloch, Noam; Kagan, Michael; Rabinovitz, Ishai; Shainer, Gilad

    2010-01-01

    This paper introduces the newly developed InfiniBand (IB) Management Queue capability, used by the Host Channel Adapter (HCA) to manage network task data flow dependancies, and progress the communications associated with such flows. These tasks include sends, receives, and the newly supported wait task, and are scheduled by the HCA based on a data dependency description provided by the user. This functionality is supported by the ConnectX-2 HCA, and provides the means for delegating collective communication management and progress to the HCA, also known as collective communication offload. This provides a means for overlapping collective communications managed by the HCA and computation on the Central Processing Unit (CPU), thus making it possible to reduce the impact of system noise on parallel applications using collective operations. This paper further describes how this new capability can be used to implement scalable Message Passing Interface (MPI) collective operations, describing the high level details of how this new capability is used to implement the MPI Barrier collective operation, focusing on the latency sensitive performance aspects of this new capability. This paper concludes with small scale benchmark experiments comparing implementations of the barrier collective operation, using the new network offload capabilities, with established point-to-point based implementations of these same algorithms, which manage the data flow using the central processing unit. These early results demonstrate the promise this new capability provides to improve the scalability of high-performance applications using collective communications. The latency of the HCA based implementation of the barrier is similar to that of the best performing point-to-point based implementation managed by the central processing unit, starting to outperform these as the number of processes involved in the collective operation increases.

  18. Ritzville 1/sup 0/ x 2/sup 0/ NTMS area, Washington: data report

    SciTech Connect

    Bennett, C.B.

    1980-07-01

    This data report presents results of ground water and stream/surface sediment reconnaissance in the National Topographic Map Series (NTMS) Ritzville 1/sup 0/ x 2/sup 0/ quadrangle. Surface samples (sediment) were collected from 1063 sites. The target sampling density was one site per 20 square kilometers (eight square miles). Dry conditions contributed to the relatively small number (109) of surface water samples collected. Ground water samples were collected at 830 sites. Neutron activation analysis (NAA) results are given for uranium and 16 other elements in sediments, and for uranium and 9 other elements in ground water. Mass spectrometry results are given for helium in ground water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps. Statistical summaries of data and a brief description of results are given. A generalized geologic map and a summary of the geology of the area are included. Data from ground water sites include: (1) water chemistry measurements (pH, conductivity, and alkalinity); (2) physical measurements where applicable (water temperature, well description, and scintillometer reading); and (3) elemental analyses (U, Al, Br, Cl, Dy, F, He, Mg, Mn, Na, and V). Data from sediment sites include: (1) stream water chemistry measurements where applicable (pH, conductivity, and alkalinity); and (2) elemental analyses for sediment samples (U, Th, Hf, Al,Ce, Dy, Eu, Fe, La, Lu, Mn, Sc, Sm, Na, Ti, V, and Yb). Sample site descriptors (stream characteristics, vegetation, etc.) are also tabulatd. Areal distribution maps, histograms, and cumulative frequency plots for most elements; U/Th, U/Hf, and Th/La ratios; and scintillometer readings for sediment samples are included on the microfiche.

  19. Elko 1/sup 0/ x 2/sup 0/ NTMS area: Nevada and Utah. Data report

    SciTech Connect

    Fay, W.M.

    1980-07-01

    Results of ground water and surface sediment reconnaissance in the National Topographic Map Series (NTMS) Elko 1/sup 0/ x 2/sup 0/ quadrangle are presented. The target sampling density was one site per 12 square kilometers. This resulted in 1713 sediment samples being collected; however, dry conditions and sparce population contributed to the relatively small number of ground water (154) samples collected. Neutron activation analysis (NAA) results are given for uranium and 16 other elements in sediments, and for uranium and 9 other elements in ground water. Mass spectrometry results are given for helium in ground water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps. Statistical summaries of data and a brief description of results are given. A generalized geologic map and a summary of the geology of the area are included. Data from ground water sites include (1) water chemistry measurements (pH, conductivity, and alkalinity), (2) physical measurements where applicable (water temperature, well description, and scintillometer reading), and (3) elemental analyses (U, Al, Br, Cl, Dy, F, He, Mg, Mn, Na, and V). Data from sediment sites include (1) stream water chemistry measurements (where available) for pH, conductivity, and alkalinity, and (2) elemental analyses (U, Th, Hf, Al, Ce, Dy, Eu, Fe, La, Lu, Mn, Sc, Sm, Na, Ti, V, and Yb). Sample site descriptors (coordinates, vegetation, etc.) are also tabulated. Areal distribution maps, histograms, and cumulative frequency plots for most elements, U/Th and U/Hf ratios, and scintillometer readings for sediment samples are included.

  20. Mineral resource assessment of the Iron River 1 degree x 2 degrees Quadrangle, Michigan and Wisconsin

    USGS Publications Warehouse

    Cannon, William F.

    1983-01-01

    The Iron River 1? x 2? quadrangle contains identified resources of copper and iron. Copper-rich shale beds in the north part of the quadrangle contain 12.2 billion pounds (5.5 billion kilograms) of copper in well-studied deposits including 9.2 billion pounds (4.2 billion kilograms) that are economically minable by 1980 standards. At least several billion pounds of copper probably exist in other parts of the same shale beds, but not enough data are available to measure the amount. A small amount, about 250 million pounds (113 million kilograms), of native copper is known to remain in one abandoned mine, and additional but unknown amounts remain in other abandoned mines. About 13.25 billion tons (12.02 billion metric tons) of banded iron-formation averaging roughly 30 percent iron are known within 500 feet (152.4 meters) of the surface in the Gogebic, Marquette, and Iron River-Crystal Falls districts. A small percentage of that might someday be minable as taconite, but none is now believed to be economic. Some higher grade iron concentrations exist in the same iron-formations. Such material was the basis of former mining of iron in the region, but a poor market for such ore and depletion of many deposits have led to the decline of iron mining in the quadrangle. Iron mines of the quadrangle were not being worked in 1980. Many parts of the quadrangle contain belts of favorable host rocks for mineral deposits. Although deposits are not known in these belts, undiscovered deposits of copper, zinc, lead, silver, uranium, phosphate, nickel, chromium, platinum, gold, and diamonds could exist.

  1. Marble Canyon 1/sup 0/ x 2/sup 0/ NTMS area Arizona: data report

    SciTech Connect

    Heffner, J.D.

    1980-07-01

    Results of ground water and stream/surface sediment reconnaissance (HSSR) in the National Topographic Map Series (NTMS) Marble Canyon 1/sup 0/ x 2/sup 0/ quadrangle are presented. The target sampling density for all media collected was one site per 12 square kilometers. This resulted in 884 sediment samples being collected; however, dry conditions and sparse population resulted in the collection of only 2 ground water samples. Grand Canyon National Park, Glen Canyon National Recreation Area, and much Indian tribal land in the southern half of the quadrangle were not sampled. Neutron activation analysis (NAA) results are given for uranium and 16 other elements in sediments, and for uranium and 9 other elements in ground water. Mass spectrometry results are given for helium in ground water. Field measurements for sediment samples are presented in tables and maps. Statistical summaries of data and a brief description of results are given. A generalized geologic map and a summary of the geology of the area are included. Data from ground water include: water chemistry measurements (pH, conductivity, and alkalinity); physical measurements (water temperature, and scintillometer readings); and elemental analyses (U, Al, Br, Cl, Dy, F, He, Mg, Mn, Na, and V). Data from sediment sites include: water chemistry measurements (where available) for pH, conductivity, and alkalinity; and elemental analyses(U, Th, Hf, Al, Ce, Dy, Eu, Fe, La, Lu, Mn, Sc, Sm, Na, Ti, V, and Yb). Sample site descriptors (stream characteristics, vegetation, etc.) are also tabulated. Histograms, cumulative frequency, and areal distribution plots for most elements; Log U/Th, Log U/Hf, and Log U/(Th + Hf) ratios; and scintillometer readings are included.

  2. Theoretical insight into the interaction between SnX2 (X = H, F, Cl, Br, I) and benzene.

    PubMed

    Matczak, Piotr

    2016-09-01

    For a series of five model complexes composed of a singlet SnX2 molecule (X = H, F, Cl, Br, I) and a benzene molecule, the first-principles calculations of their energetics and the analysis of their electron density topology have been performed. The CCSD(T)/CBS interaction energy between SnX2 and C6H6 fall into the range between -10.0 and -11.2 kcal/mol, which indicates that the complexes are rather weakly bound. The relevant role of electrostatic and dispersion contributions to the interaction energy between SnX2 and C6H6 is highlighted in the results obtained from the symmetry-adapted perturbation theory (SAPT). The electron density topological analysis has been carried out using the quantum theory of atoms in molecules (QTAIM) and the noncovalent interactions (NCI) visualization index. Both QTAIM and NCI prove the closed-shell, noncovalent and attractive character of the interaction. A very small charge transfer from C6H6 to SnX2 has been detected. The formation of the five complexes is accompanied by the electron density deformations that are spatially restricted mostly to the region around the Sn atom and its adjacent C atom. The results presented in this work shed some light on the nature of the interactions associated with crystalline structural motifs involving low-valent tin complexed with neutral aryl rings. PMID:27525639

  3. Factor Structure and Predictive Utility of the 2 x 2 Achievement Goal Model in a Sample of Taiwan Students

    ERIC Educational Resources Information Center

    Chiang, Yu-Tzu; Yeh, Yu-Chen; Lin, Sunny S. J.; Hwang, Fang-Ming

    2011-01-01

    This study examined structure and predictive utility of the 2 x 2 achievement goal model among Taiwan pre-university school students (ages 10 to 16) who learned Chinese language arts. The confirmatory factor analyses of Achievement Goal Questionnaire-Chinese version provided good fitting between the factorial and dimensional structures with the…

  4. On Association Coefficients for 2x2 Tables and Properties that Do Not Depend on the Marginal Distributions

    ERIC Educational Resources Information Center

    Warrens, Matthijs J.

    2008-01-01

    We discuss properties that association coefficients may have in general, e.g., zero value under statistical independence, and we examine coefficients for 2x2 tables with respect to these properties. Furthermore, we study a family of coefficients that are linear transformations of the observed proportion of agreement given the marginal…

  5. Students' Attitudes and Perceived Purposes of Physical Education in Singapore: Perspectives from a 2 x 2 Achievement Goal Framework

    ERIC Educational Resources Information Center

    Wang, C. K.; Lim, B. S.; Aplin, N. G.; Chia, Y. H. M.; McNeill, M.; Tan, W. K.

    2008-01-01

    The aim of the present study was to re-examine the relationships between achievement goals and perceived purposes of PE, perceived motivational climates, attitudes towards PE teachers and affective outcomes using the 2 x 2 achievement goal framework. Questionnaires were completed by 493 secondary school students (222 males, 262 females, 9 missing)…

  6. Optical Stark Spectroscopy of the tilde{A}2Π- tilde{X}2Σ+ Band of BaOH

    NASA Astrophysics Data System (ADS)

    Frey, Sarah E.; Steimle, Timothy C.

    2011-06-01

    Transitions of the tilde{A}2Π- tilde{X}2Σ+ band system of barium monohydroxide, BaOH, were observed and recorded from 11483-11485 Cm-1 and 12041-12044 Cm-1. The features were readily identified using the results of the Doppler-limited measurements. The laser induced fluorescence (LIF) spectrum was analyzed to give optimized field-free excited state parameters. The parameters for the tilde{X}2Σ+ state were constrained to the previously determined values. The permanent electric dipole moments for the tilde{X}2Σ+ and tilde{A}2Π states have been determined from the analysis of the optical Stark spectra for the R21(0.5), Q21(1.5), and R2(0.5) lines. The obtained values were μ(tilde{X}2Σ+)= 1.426(38)D and μ(tilde{A}2Π)= 0.477(7) D. The results are compared with predicted values from semi-empirical models and those for CaOH and SrOH. J. G. Wang, J. D. Tandy and P. F. Bernath J. Mol. Spectrosc. 252, 31 (2008) M. A. Anderson, M. D. Allen, W. L. Barclay, Jr, and L. M. Ziurys Chem. Phys. Lett 205, 415 (1993) T. C. Steimle, D. A. Fletcher, K. Y. Jung and C. T. Scurlock J. Chem. Phys. 96, 2556 (1992).

  7. Crossed beam study of the atom-radical reaction of ground state carbon atoms (C(3P)) with the vinyl radical (C2H3(X2A')).

    PubMed

    Wilson, Antony V; Parker, Dorian S N; Zhang, Fangtong; Kaiser, Ralf I

    2012-01-14

    The atom-radical reaction of ground state carbon atoms (C((3)P)) with the vinyl radical (C(2)H(3)(X(2)A')) was conducted under single collision conditions at a collision energy of 32.3 ± 2.9 kJ mol(-1). The reaction dynamics were found to involve a complex forming reaction mechanism, which is initiated by the barrier-less addition of atomic carbon to the carbon-carbon-double bond of the vinyl radical forming a cyclic C(3)H(3) radical intermediate. The latter has a lifetime of at least 1.5 times its rotational period and decomposes via a tight exit transition state located about 45 kJ mol(-1) above the separated products through atomic hydrogen loss to the cyclopropenylidene isomer (c-C(3)H(2)) as detected toward cold molecular clouds and in star forming regions.

  8. OH/A 2 Sigma + - X 2 Pi sub i/ yield from H2O photodissociation in 1050-1370 A

    NASA Technical Reports Server (NTRS)

    Lee, L. C.

    1980-01-01

    The cross section and quantum yield for the production of the OH(A 2 Sigma + - X 2 Pi sub i) emission from H2O photodissociation by synchrotron radiation in the region 1050-1370 A are determined. Measurements of the photoemission and photoabsorption cross sections obtained for incident radiation bandwidths of 2 A reveal different vibrational structures in the range 1250-1370 A, and the photoemission is attributed to the 3a1-4a1 valence and 3a1-3sa1 Rydberg transitions. Photoemission quantum yields determined from the ratio of photoemission to photoabsorption cross sections are found to increase sharply at a threshold of 1362-5 A to a peak of 11% at 1300 A, then to decrease slowly with decreasing wavelength. Implications of the results for the dissociation processes of H2O are considered.

  9. Si(011)16x2 gas-source molecular beam epitaxy: Growth kinetics

    SciTech Connect

    Taylor, N.; Kim, H.; Desjardins, P.; Foo, Y. L.; Greene, J. E.

    2000-05-15

    The growth rates R{sub Si} of Si layers deposited on Si(011)''16x2'' by gas-source molecular beam epitaxy from Si{sub 2}H{sub 6} were determined as a function of temperature T{sub s} (400-975 degree sign C) and Si{sub 2}H{sub 6} flux J{sub Si{sub 2}}{sub H{sub 6}}(5.0x10{sup 15}-9.0x10{sup 16} cm{sup -2} s{sup -1}). R{sub Si} ranges from 0.0015 {mu}m h-1 at T{sub s}=400 degree sign C to 0.415 {mu}m h-1 at T{sub s}=975 degree sign C with J{sub Si{sub 2}}{sub H{sub 6}}=2.2x10{sup 16} cm{sup -2} s{sup -1}. In the surface-reaction-limited regime at T{sub s}<725 degree sign C, R{sub Si} initially exhibits an exponential decrease with 1/T{sub s}, then decreases at a slower rate at T{sub s}{<=}550 degree sign C as an additional deposition pathway becomes operative. In the impingement-flux-limited regime, 725{<=}T{sub s}{<=}900 degree sign C, R{sub Si} is independent of T{sub s} but increases linearly with J{sub Si{sub 2}}{sub H{sub 6}}. At T{sub s}>900 degree sign C, R{sub Si}(T{sub s}) increases with T{sub s} due to surface roughening. Overall, R{sub Si}(J{sub Si{sub 2}}{sub H{sub 6}},T{sub s}) is well described at T{sub s}{<=}900 degree sign C by a kinetic model incorporating two competing film growth mechanisms: (1) dissociative chemisorption of Si{sub 2}H{sub 6} onto dangling bonds followed by fast surface dissociation steps and second-order H{sub 2} desorption from the surface monohydride phase; and (2) Si{sub 2}H{sub 6} insertion into Si-H surface bonds followed by second-order desorption of SiH{sub 4}. (c) 2000 American Institute of Physics.

  10. Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) heteropolyacid nano-catalysts for catalytic decomposition of 2,3-dihydrobenzofuran to aromatics.

    PubMed

    Kim, Jeong Kwon; Park, Hai Woong; Hong, Ung Gi; Choi, Jung Ho; Song, In Kyu

    2014-11-01

    Cesium-exchanged Cs(x)H(3.0-x)PW12O40 (X = 2.0, 2.3, 2.5, 2.8, and 3.0) heteropolyacid nanocatalysts were prepared, and they were applied to the catalytic decomposition of lignin model compound to aromatics. Successful formation of cesium-exchanged Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) catalysts was confirmed by FT-IR, ICP-AES, and XRD measurements. 2,3-Dihydrobenzofuran was employed as a lignin model compound for representing β-5 bond in lignin. Phenol, ethylbenzene, and 2-ethylphenol were mainly produced by the catalytic decomposition of 2,3-dihydrobenzofuran. Conversion of 2,3-dihydrobenzofuran and total yield for main products (phenol, ethylbenzene, and 2-ethylphenol) were closely related to the surface acidity of Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) catalysts. Conversion of 2,3-dihydrobenzofuran and total yield for main products increased with increasing surface acidity of the catalysts. Among the catalysts tested, Cs2.5H0.5PW12O40 with the largest surface acidity showed the highest conversion of 2,3-dihydrobenzofuran and the highest total yield for main products. These results indicate that surface acidity of Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) catalysts served as an important factor determining the catalytic performance in the decomposition of 2,3-dihydrobenzofuran to aromatics.

  11. New Theoretical Line List for the B' 2Σ+<--X 2Σ+ System of 24MgH

    NASA Astrophysics Data System (ADS)

    Skory, S.; Weck, P. F.; Stancil, P. C.; Kirby, K.

    2003-10-01

    Fully quantum-mechanical techniques have been applied to compute the complete line list for the B'2Σ+<--X2Σ+ system of 24MgH. The list includes transition energies and oscillator strengths over the wavelength range 11,850-32,130 cm-1, for all possible allowed transitions from the ground electronic state vibrational levels v''=0-11. This list was computed using the best available ab initio potential energies and dipole transition moment function, with the former adjusted to account for experimental data. The agreement of the current calculations with previous theoretical results and the line list of Kurucz is discussed. Although spectroscopic accuracy for a particular line cannot be claimed for our calculations, comparison is made with the recent astronomical measurements of Wallace et al. A line list for pure rovibrational transitions in the X2Σ+ state is also presented.

  12. Parity violation energies of C4H4X2 molecules for X = O, S, Se, Te and Po†

    NASA Astrophysics Data System (ADS)

    Pelloni, Stefano; Faglioni, Francesco; Lazzeretti, Paolo

    2013-09-01

    Parity-violating contributions, with the same magnitude but opposite sign, to the energies of 1,2 enantiomers of dioxin, dithiin, diselenin, ditellurin and dipolonin have been calculated. Theoretical predictions, which can be classified among the largest reported so far, indicate that the P enantiomer is energetically more stable than M. As expected, parity-violating effects increase with the first power of the neutron number and the fourth power of the atomic number for X = O, S, Se, Te and Po. The trend predicted by Laerdahl and Schwerdtfeger [Phys. Rev. A 60, 4439 (1999)] and by Berger [J. Chem. Phys. 129, 154105 (2008)] for H2X2 molecules, characterised by free rotation about the X-X internuclear axis, is therefore confirmed for the series of more rigid C4H4X2 compounds, in which limited deformations can take place.

  13. Growth of an {alpha}-Sn film on an InSb(111) A-(2x2) surface

    SciTech Connect

    Kondo, Daiyu; Sakamoto, Kazuyuki; Shima, Masahide; Takeyama, Wakaba; Nakamura, Kenya; Ono, Kanta; Oshima, Masaharu; Kasukabe, Yoshitaka

    2004-12-15

    We have investigated the initial growth process of {alpha}-Sn films on the In-terminated InSb(111)A-(2x2) surface using low-energy electron diffraction (LEED) and high-resolution core-level photoelectron spectroscopy. Taking the LEED observation and the Sn coverage-dependent integrated intensities of the In 4d, Sb 4d, and Sn 4d core-level spectra into account, we conclude that the {alpha}-Sn film grows epitaxially by a bilayer mode and that there is no interdiffusion of the substrate atoms as suggested in the literature. Furthermore, the coverage-dependent In 4d and Sn 4d core levels indicate that the In vacancy site of InSb(111)A-(2x2) surface is not the preferable Sn absorption site.

  14. Silicene/germanene on MgX2 (X = Cl, Br, and I) for Li-ion battery applications

    NASA Astrophysics Data System (ADS)

    Zhu, Jiajie; Chroneos, Alexander; Schwingenschlögl, Udo

    2016-03-01

    Silicene is a promising electrode material for Li-ion batteries due to its high Li capacity and low Li diffusion barrier. Germanene is expected to show a similar performance due to its analogous structural and electronic properties. However, the performance of both the materials will be determined by the substrate, since freestanding configurations are unstable. We propose Si/MgX2 and Ge/MgX2 (X = Cl, Br, and I) as suitable hybrid structures, based on first-principles calculations. We find that Li will not cluster and that the Li capacity is very high (443 and 279 mA h g-1 for silicene and germanene on MgCl2, respectively). Sandwich structures can be used to further enhance the performance. Low diffusion barriers of less than 0.3 eV are predicted for all the hybrid structures.

  15. The rotational spectrum of the NH+ radical in its X 2Pi and a 4Sigma- states.

    PubMed

    Hübers, Heinz-Wilhelm; Evenson, Kenneth M; Hill, Christian; Brown, John M

    2009-07-21

    Transitions between the spin-rotational levels of the (14)NH(+) radical in the v = 0 levels of its X (2)Pi and a (4)Sigma(-) states have been studied by the technique of laser magnetic resonance at far-infrared wavelengths. The data have been combined with a previous zero-field measurement of the J = 1 1/2 - 1/2 transition frequencies at 1.01 THz to determine a much improved set of molecular parameters for NH(+) in the X (2)Pi state; the major parameters for the a (4)Sigma(-) state have also been determined. A full determination of the hyperfine parameters for both (14)N and (1)H nuclei has been achieved for the first time. Accurate predictions of the transition frequencies between the low-lying levels of the radical in the absence of a magnetic field have also been made, including lambda-doubling frequencies for use by radio astronomers. PMID:19624201

  16. Ab initio potential energy surfaces describing the interaction of CH(X2Π) with H2

    NASA Astrophysics Data System (ADS)

    Dagdigian, Paul J.

    2016-09-01

    We have determined four-dimensional ab initio quasi-diabatic potential energy surfaces describing the interaction of CH(X2Π) with H2, under the assumption of fixed CH and H2 internuclear separations. These calculations employed the multi-reference configuration interaction method [MRCISD+Q(Davidson)]. The computed points were fit to an analytical form suitable for time-independent quantum scattering calculations of rotationally inelastic cross sections and rate constants.

  17. VizieR Online Data Catalog: MgH in the A2{Pi}-X2{Sigma}+

    NASA Astrophysics Data System (ADS)

    Hinkle, K. H.; Wallace, L.; Ram, R. S.; Bernath, P. F.; Sneden, C.; Lucatello, S.

    2013-09-01

    Rotationally resolved lines within the A2{Pi}-X2{ transition of the 25MgH and 26MgH isotopologues were measured from spectra recorded by J. Black, P. F. Bernath, C. R. Brazier, and R. Hubbard in 1984 (National Solar Observatory (NSO) archive reference 1984/03/13/#2) with the 1m Fourier transform spectrometer associated with the McMath-Pierce Solar Telescope of the NSO at Kitt Peak. (6 data files).

  18. Stabilization of the O p2x2 phase on Cu(001) sheltered by wrinkled BN over-layer

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Sung; Ma, Chuanxu; Li, An-Ping; Yoon, Mina

    The 2 √3x √3R45°phase of oxygen (O) on the Cu(001) surface has been observed in scanning tunneling microscopy (STM) measurements. Although the p2x2 phase of O on the Cu(001) surface has been proposed theoretically to be the most stable in O-lean conditions, it has not been observed in experiments for a long time. Recently, the O p2x2 phase has been found in STM on the Cu(001) surface with an overlying BN monolayer. In this theoretical study, we investigate what the role of BN over-layer is to stabilize the O p2x2 phase on the Cu(001) surface. The BN over-layer is lattice-matched with the Cu(001) surface and the BN mono-layer sheet is periodically wrinkled along the BN arm-chair direction and along the [100] or [010] direction on the Cu(001) surface. The interlayer space between the Cu(001) surface and the bulge of the wrinkled BN sheet is found to play as a preferential shelter for O to be adsorbed, and the boundary of the BN inner wall along the [010] or [100] direction makes the p2x2 phase more favorable against the 45°-tilted 2 √3x √3R45°phase of O on the Cu(001) surface. This was supported by Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility, and the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, maaged by UT-Battelle, LLC, for the U. S. DOE.

  19. Probing the electronic structures of low oxidation-state uranium fluoride molecules UFx- (x=2-4)

    SciTech Connect

    Li, Wei-Li; Hu, Hanshi; Jian, Tian; Lopez, Gary V.; Su, Jing; Li, Jun; Wang, Lai-Sheng

    2013-12-28

    We report the experimental observation of gaseous UFx- (x = 2-4) anions, which are investigated using photoelectron spectroscopy and relativistic quantum chemistry. Vibrationally resolved photoelectron spectra are obtained for all three species and the electron affinities of UFx (x = 2-4) are measured to be 1.16(3), 1.09(3), and 1.58(3) eV, respectively. Significant multi-electron transitions are observed in the photoelectron spectra of U(5f(3)7s(2)) F-2(-), as a result of strong electron correlation effects of the two 7s electrons. The U-F symmetric stretching vibrational modes are resolved for the ground states of all UFx (x = 2-4) neutrals. Theoretical calculations are performed to qualitatively understand the photoelectron spectra. The entire UFx- and UFx (x = 1-6) series are considered theoretically to examine the trends of U-F bonding and the electron affinities as a function of fluorine coordination. The increased U-F bond lengths and decreased bond orders from UF2- to UF4- indicate that the U-F bonding becomes weaker as the oxidation state of U increases from I to III. (C) 2013 AIP Publishing LLC.

  20. Antitumour Metallocenes: Effect of DMSO on the Stability of Cp2TiX2 and Implications for Anticancer Activity

    PubMed Central

    Mokdsi, George

    1998-01-01

    The rate of hydrolysis of the aromatic rings of Cp2TiX2 [X = CI 1, O2CCCl3 8 and O2CCH2NH3Cl 13], in aqueous solutions, 10%DMSO and 100% DMSO have been studied by 1H NMR spectroscopy. Rapid hydrolysis of both the carboxylate and cyclopentadienyl ligands in Cp2TiX2[X = O2CCCl3,O2CCH2NH3Cl] occurs in DMSO to give biologically inactive species. The rate of these reactions are concentration dependent as dilution of these samples with saline or water to give the therapeutic conditions of 10%DMSO/90%H2O slows the hydrolysis chemistry. In contrast, samples of Cp2TiX2 [X = CI 1, O2CCH2NH3Cl13 ], dissolved in water give solutions containing the presumed antitumour active species in which the halide or glycine ligands have been hydrolysed but the Cp rings remain metal bound. PMID:18475845

  1. Draft Genome Sequence of the Bacterium Lysobacter capsici X2-3, with a Broad Spectrum of Antimicrobial Activity against Multiple Plant-Pathogenic Microbes

    PubMed Central

    Yi, Jing-Li; Wang, Jing; Li, Qun; Liu, Zhao-xia; Zhang, Li; Yu, Jin-Feng

    2015-01-01

    Lysobacter capsici strain X2-3 was isolated from the wheat rhizosphere in China and exhibits a remarkable capacity to inhibit the growth of multiple pathogens. Here, we report the draft genome sequence of L. capsici strain X2-3 in China. PMID:26044432

  2. Ab initio study on the spectroscopy of CuCl2. II. Benchmark calculations on the X 2Πg-C 2Δg and X 2Πg-D 2Δg transitions

    NASA Astrophysics Data System (ADS)

    Ramírez-Solís, A.; Daudey, J. P.

    2005-01-01

    The X 2Πg-C2Δg and X 2Πg-D2Δg transitions on CuCl2 have been studied using the most sophisticated nondynamic and dynamic electronic correlation treatments. We report here ab initio benchmark calculations using especially developed basis sets to study, at the complete active space self-consistent field plus second-order Möller-Plesset algorithm (CASSCF+CASPT2) and CASSCF+ACPF levels, the transition energies as well as the corresponding equilibrium geometries (ACPF—averaged coupled pair functional). The spin-orbit (SO) effects of both atoms were included in a second step through the effective Hamiltonian formalism, using the calibrated SO effective potentials developed by the Stuttgart group. Without SO at the CASSCF+ACPF level, the vertical excitation energy for the 2Δg state is 6711 cm-1 and the symmetric stretching equilibrium Cu-Cl distance is 4.04 a.u. The inclusion of the SO effects leads to a pure 2Δg Ω=5/2C state and a Ω=3/2 (0.7% 2Πg,99.3%2Δg)D state. The calculated transition energies for the C and D states are 6340 and 8020 cm-1, in good agreement with the spin-orbit splitting recent values from gas-phase and rare-gas matrix isolation laser induced fluorescence experiments. The present benchmark results show, as was recently done for the X 2Πg-2Σg transition, the rather poor performance of all the density functional theory-based descriptions for the 2Δg state, which largely overestimate its Te, systematically placing it around 19 000 cm-1. The CASSCF+CASPT2 method also overestimates, by around 50%, the X 2Πg-2Δg transition energy, showing that only large variational calculations can produce reliable spectroscopic results for this kind of complex systems where delicate electronic correlation effects have to be carefully dealt with.

  3. ConnectX-2 CORE-Direct Enabled Asynchronous Broadcast Collective Communications

    SciTech Connect

    Gorentla Venkata, Manjunath; Graham, Richard L; Ladd, Joshua S; Shamis, Pavel; Rabinovitz, Ishai; Filipov, Vasily; Shainer, Gilad

    2011-01-01

    This paper describes the design and implementation of InfiniBand (IB) CORE-Direct based blocking and nonblocking broadcast operations within the Cheetah collective operation framework. It describes a novel approach that fully ofFLoads collective operations and employs only user-supplied buffers. For a 64 rank communicator, the latency of CORE-Direct based hierarchical algorithm is better than production-grade Message Passing Interface (MPI) implementations, 150% better than the default Open MPI algorithm and 115% better than the shared memory optimized MVAPICH implementation for a one kilobyte (KB) message, and for eight mega-bytes (MB) it is 48% and 64% better, respectively. Flat-topology broadcast achieves 99.9% overlap in a polling based communication-computation test, and 95.1% overlap for a wait based test, compared with 92.4% and 17.0%, respectively, for a similar Central Processing Unit (CPU) based implementation.

  4. Biodegradation of C.I. Acid Red 1 by indigenous bacteria Stenotrophomonas sp. BHUSSp X2 isolated from dye contaminated soil.

    PubMed

    Kumari, Lata; Tiwary, Dhanesh; Mishra, Pradeep Kumar

    2016-03-01

    A significant proportion of xenobiotic recalcitrant azo dyes are being released in environment during carpet dyeing. The bacterial strain Stenotrophomonas sp. BHUSSp X2 was isolated from dye contaminated soil of carpet industry, Bhadohi, India. The isolated bacterial strain was identified morphologically, biochemically, and on the basis of 16S rRNA gene sequence. The isolate decolorized 97 % of C.I. Acid Red 1 (Acid RED G) at the concentration of 200 mg/l within 6 h under optimum static conditions (temperature -35 °C, pH 8, and initial cell concentration 7 × 10(7) cell/ml). Drastic reduction in dye degradation rate was observed beyond initial dye concentration from 500 mg/l (90 %), and it reaches to 25 % at 1000 mg/l under same set of conditions. The analysis related to decolorization and degradation was done using UV-Vis spectrophotometer, HPLC, and FTIR, whereas the GC-MS technique was utilized for the identification of degradation products. Phytotoxicity analysis revealed that degradation products are less toxic as compared to the original dye.

  5. Modulation of P2X3 and P2X2/3 Receptors by Monoclonal Antibodies.

    PubMed

    Shcherbatko, Anatoly; Foletti, Davide; Poulsen, Kris; Strop, Pavel; Zhu, Guoyun; Hasa-Moreno, Adela; Melton Witt, Jody; Loo, Carole; Krimm, Stellanie; Pios, Ariel; Yu, Jessica; Brown, Colleen; Lee, John K; Stroud, Robert; Rajpal, Arvind; Shelton, David

    2016-06-01

    Purinergic homomeric P2X3 and heteromeric P2X2/3 receptors are ligand-gated cation channels activated by ATP. Both receptors are predominantly expressed in nociceptive sensory neurons, and an increase in extracellular ATP concentration under pathological conditions, such as tissue damage or visceral distension, induces channel opening, membrane depolarization, and initiation of pain signaling. Hence, these receptors are considered important therapeutic targets for pain management, and development of selective antagonists is currently progressing. To advance the search for novel analgesics, we have generated a panel of monoclonal antibodies directed against human P2X3 (hP2X3). We have found that these antibodies produce distinct functional effects, depending on the homomeric or heteromeric composition of the target, its kinetic state, and the duration of antibody exposure. The most potent antibody, 12D4, showed an estimated IC50 of 16 nm on hP2X3 after short term exposure (up to 18 min), binding to the inactivated state of the channel to inhibit activity. By contrast, with the same short term application, 12D4 potentiated the slow inactivating current mediated by the heteromeric hP2X2/3 channel. Extending the duration of exposure to ∼20 h resulted in a profound inhibition of both homomeric hP2X3 and heteromeric hP2X2/3 receptors, an effect mediated by efficient antibody-induced internalization of the channel from the plasma membrane. The therapeutic potential of mAb12D4 was assessed in the formalin, complete Freund's adjuvant, and visceral pain models. The efficacy of 12D4 in the visceral hypersensitivity model indicates that antibodies against P2X3 may have therapeutic potential in visceral pain indications. PMID:27129281

  6. Kinetics versus thermodynamics of the metal incorporation in molecular beam epitaxy of (InxGa1-x)2O3

    NASA Astrophysics Data System (ADS)

    Vogt, Patrick; Bierwagen, Oliver

    2016-08-01

    We present a detailed study of the reaction kinetics and thermodynamics of the plasma-assisted oxide molecular beam epitaxy of the ternary compound (InxGa1-x)2O3 for 0 ≤ x ≤ 1. We measured the growth rate of the alloy in situ by laser reflectrometry as a function of growth temperature TG for different metal-to-oxygen flux ratios rMe, and nominal In concentrations xnom in the metal flux. We determined ex situ the In and Ga concentrations in the grown film by energy dispersive X-ray spectroscopy. The measured In concentration x shows a strong dependence on the growth parameters TG, rMe, and xnom whereas growth on different co-loaded substrates shows that in the macroscopic regime of ˜μm3 x does neither depend on the detailed layer crystallinity nor on crystal orientation. The data unveil that, in presence of In, Ga incorporation is kinetically limited by Ga2O desorption the same way as during Ga2O 3 growth. In contrast, In incorporation during ternary growth is thermodynamically suppressed by the presence of Ga due to stronger Ga-O bonds. Our experiments revealed that Ga adatoms decompose/etch the In-O bonds whereas In adatoms do not decompose/etch the Ga-O bonds. This result is supported by our thermochemical calculations. In addition we found that a low TG and/or excessively low rMe kinetically enables In incorporation into (InxGa1-x)2O3. This study may help growing high-quality ternary compounds (InxGa1-x)2O3 allowing band gap engineering over the range of 2.7-4.7 eV.

  7. Effects of substitution, pressure, and temperature on the phonon mode in layered-rocksalt-type Li(1-x/2)Ga(1-x/2)ZnxO (x = 0.036-0.515) alloys

    NASA Astrophysics Data System (ADS)

    Tan, Lijie; Hu, Qiwei; Lei, Li; Jiang, Xiaodong; Gao, Shangpan; He, Duanwei

    2015-11-01

    ZnO-based semiconductor alloys, Li(1-x/2)Ga(1-x/2)ZnxO (x = 0.036-0.515) with a layered-rocksalt-type structure, have been prepared under high pressure. The composition, pressure, and temperature dependence of phonons have been studied by Raman spectroscopy. We observe two disorder-activated Raman (DAR) modes when the Zn composition x increases: a broad Raman peak at ca. 400 cm-1 and a left-shoulder peak at ca. 530 cm-1 on the low-frequency side of A1g mode at ca. 580 cm-1, which can be explained by reference to the phonon density of states for rocksalt-type ZnO. With the increase of the pressure and temperature, the left-shoulder DAR mode induced by substitution does not change at the same pace with the A1g mode at Brillouin-zone center. We find that ion substitution can be seen as a kind of chemical pressure, and the chemical pressure caused by internal substitution and the physical pressure caused by external compression have equivalent effects on the shortening of correlation length, the distortion of crystal lattice, and the change of atomic occupation.

  8. UNR facilitates the interaction of MLE with the lncRNA roX2 during Drosophila dosage compensation.

    PubMed

    Militti, Cristina; Maenner, Sylvain; Becker, Peter B; Gebauer, Fátima

    2014-01-01

    Dosage compensation is a regulatory process that balances the expression of X-chromosomal genes between males (XY) and females (XX). In Drosophila, this requires non-coding RNAs and RNA-binding proteins (RBPs) whose specific functions remain elusive. Here we show that the Drosophila RBP UNR promotes the targeting of the activating male-specific-lethal complex to the X-chromosome by facilitating the interaction of two crucial subunits: the RNA helicase MLE and the long non-coding RNA roX2.

  9. Blackbody infrared radiative dissociation at low temperature: hydration of X2+(H2O)n, for X = Mg, Ca

    NASA Astrophysics Data System (ADS)

    Wong, Richard L.; Paech, Kolja; Williams, Evan R.

    2004-03-01

    A new apparatus for making blackbody infrared radiative dissociation (BIRD) measurements at below ambient temperature is described, and its use for measuring threshold dissociation energies of weakly bound clusters is demonstrated. Hydration energies are determined for alkaline-earth metal water clusters, X2+(H2O)n, X=Mg, Ca and n=8-10. For n=8 and 9, the energies obtained from BIRD measurements are in excellent agreement with values reported previously, but for n=10, the energies are slightly lower than those determined previously using the high-pressure ion source mass spectrometry (HPMS) equilibrium method.

  10. A possible 55-d X-ray period of the ultraluminous accreting pulsar M82 X-2

    NASA Astrophysics Data System (ADS)

    Kong, Albert K. H.; Hu, Chin-Ping; Lin, Lupin Chun-Che; Li, K. L.; Jin, Ruolan; Liu, C. Y.; Yen, David Chien-Chang

    2016-10-01

    We report on the possible detection of a 55-d X-ray modulation for the ultraluminous accreting pulsar M82 X-2 from archival Chandra observations. Because M82 X-2 is known to have a 2.5-d orbital period, if the 55-d period is real, then it will be the superorbital period of the system. We also investigated variabilities of three other nearby ultraluminous X-ray sources in the central region of M82 with the Chandra data, and we did not find any evidence of periodicities. Furthermore, we re-examined the previously reported 62-d periodicity near the central region of M82 by performing a systematic timing study with all the archival Rossi X-Ray Timing Explorer and Swift data. Using various dynamic timing analysis methods, we have confirmed that the 62-d period is not stable, suggesting that it is not the orbital period of M82 X-1; this is in agreement with previous work.

  11. Strain-induced giant second-harmonic generation in monolayered 2H-MoX2 (X = S, Se, Te)

    NASA Astrophysics Data System (ADS)

    Rhim, S. H.; Kim, Yong Soo; Freeman, A. J.

    2015-12-01

    Dynamic second-order nonlinear susceptibilities, χ(2)(2 ω,ω,ω)≡χ(2)(ω) , are calculated here within a fully first-principles scheme for monolayered molybdenum dichalcogenides, 2H-MoX2 (X = S, Se, and Te). The absolute values of χ(2)(ω) across the three chalcogens critically depend on the band gap energies upon uniform strain, yielding the highest χ(2)(0 )˜140 pm/V for MoTe2 in the static limit. Under this uniform in-plane stress, 2H-MoX2 can undergo direct-to-indirect transition of band gaps, which in turn substantially affects χ(2)(ω) . The tunability of χ(2)(ω) by either compressive or tensile strain is demonstrated especially for two important experimental wavelengths, 1064 nm and 800 nm, where resonantly enhanced non-linear effects can be exploited: χ(2) of MoSe2 and MoTe2 approach ˜800 pm/V with -2% strain at 1064 nm.

  12. Magnetic phase separation in double layer ruthenates Ca3(Ru(1-x)Ti(x))2O7.

    PubMed

    Peng, Jin; Liu, J Y; Hu, J; Mao, Z Q; Zhang, F M; Wu, X S

    2016-01-01

    A phase transition from metallic AFM-b antiferromagnetic state to Mott insulating G-type antiferromagnetic (G-AFM) state was found in Ca3(Ru(1-x)Ti(x))2O7 at about x = 0.03 in our previous work. In the present, we focused on the study of the magnetic transition near the critical composition through detailed magnetization measurements. There is no intermediate magnetic phases between the AFM-b and G-AFM states, which is in contrasted to manganites where a similar magnetic phase transition takes place through the presence of several intermediate magnetic phases. The AFM-b-to-G-AFM transition in Ca3(Ru(1-x)Ti(x))2O7 happens through a phase separation process in the 2-5% Ti range, whereas similar magnetic transitions in manganites are tuned by 50-70% chemical substitutions. We discussed the possible origin of such an unusual magnetic transition and compared with that in manganites.

  13. Quantum scattering studies of electronically inelastic collisions of N + 2(X 2Sigma + g, A 2Pi u) with He

    NASA Astrophysics Data System (ADS)

    Berning, Andreas; Werner, Hans-Joachim

    1994-02-01

    The potential energy surfaces (PESs) of the three lowest electronic states of the system N+2+He have been computed using accurate multiconfiguration-reference configuration (MRCI) wave functions and a large basis set. The approach of the He atom leads to nonadiabatic mixing of the A 2Πu(A') and X 2Σ+g(A') states of N+2. The three adiabatic interaction potentials have been transformed into a set of four diabatic potentials, one of which describes the collision-induced nonadiabatic coupling between the two A' states. The computed potentials have been fitted to analytical functions and used in quantum scattering calculations for electronically inelastic transitions between individual rovibrational levels of the A 2Πu and the X 2Σ+g states of N+2. Our results are compared to transitions observed experimentally by Katayama and co-workers between the rotational levels of the A,v=3 and 4 and X,v=6, 7, and 8 vibrational manifolds. In general, good agreement is found for transitions between nearly isoenergetic vibrational states. However, for transitions which traverse large energy gaps, we obtained cross sections which are several orders of magnitude smaller than experimentally observed. Inclusion of the vibrational degree of freedom of the N+2 molecule in the scattering calculations was found to have only an insignificant effect on the transition probabilities.

  14. The Pure Rotational Spectra of TiO( X3Δ) and TiN( X2Σ +)

    NASA Astrophysics Data System (ADS)

    Namiki, Kei-ichi; Saito, Shuji; Robinson, J. Scott; Steimle, Timothy C.

    1998-09-01

    The pure rotational transitions in the 220-460 GHz spectral range of TiO (X3Δr) and TiN(X2Σ+) have been observed using a source-modulated submillimeter-wave spectrometer. In addition, the two lowest rotational transitions of TiO at 63 and 94 GHz have been observed using molecular beam pump/probe microwave optical double resonance (PPMODR) technique. An improved set of spectroscopic parameters for TiO(X3Δ) was generated by combining the new PPMODR and submillimeter-wave absorption measurements. Similarly, an improved set of spectroscopic parameters for TiN(X2Σ+) was generated by combining the new submillimeter-wave absorption measurements with the previously recorded PPMODR measurements (D. A. Fletcher, C. T. Scurlock, K. Y. Jung, and T. C. Steimle, 1993,J. Chem. Phys.99, 4288). The determined Λ-type doubling parameter for the TiO(X3Δ) is compared with the theoretical model.

  15. Microbial antibiotic production aboard the International Space Station.

    PubMed

    Benoit, M R; Li, W; Stodieck, L S; Lam, K S; Winther, C L; Roane, T M; Klaus, D M

    2006-04-01

    Previous studies examining metabolic characteristics of bacterial cultures have mostly suggested that reduced gravity is advantageous for microbial growth. As a consequence, the question of whether space flight would similarly enhance secondary metabolite production was raised. Results from three prior space shuttle experiments indicated that antibiotic production was stimulated in space for two different microbial systems, albeit under suboptimal growth conditions. The goal of this latest experiment was to determine whether the enhanced productivity would also occur with better growth conditions and over longer durations of weightlessness. Microbial antibiotic production was examined onboard the International Space Station during the 72-day 8A increment. Findings of increased productivity of actinomycin D by Streptomyces plicatus in space corroborated with previous findings for the early sample points (days 8 and 12); however, the flight production levels were lower than the matched ground control samples for the remainder of the mission. The overall goal of this research program is to elucidate the specific mechanisms responsible for the initial stimulation of productivity in space and translate this knowledge into methods for improving efficiency of commercial production facilities on Earth.

  16. Growth characteristics of corundum-structured α-(AlxGa1-x)2O3/Ga2O3 heterostructures on sapphire substrates

    NASA Astrophysics Data System (ADS)

    Kaneko, Kentaro; Suzuki, Kenta; Ito, Yoshito; Fujita, Shizuo

    2016-02-01

    We report improved growth conditions for corundum-structured α-(AlxGa1-x)2O3, followed by the growth characteristics of α-(AlxGa1-x)2O3/Ga2O3 heterostructures with the use of mist chemical vapor deposition (CVD) technology. Higher growth temperatures, 700-800 °C, were effective for better crystalline quality especially for higher Al composition x. Coherent growth of α-(AlxGa1-x)2O3 was achieved for x=0.03 and 0.11 with the film thickness of about 100 nm. The type-I band lineup was expected for the heterostructure.

  17. Ce(x)O(y)⁻ (x = 2-3) + D₂O reactions: stoichiometric cluster formation from deuteroxide decomposition and anti-Arrhenius behavior.

    PubMed

    Felton, Jeremy A; Ray, Manisha; Waller, Sarah E; Kafader, Jared O; Jarrold, Caroline Chick

    2014-10-30

    Reactions between small cerium oxide cluster anions and deuterated water were monitored as a function of both water concentration and temperature in order to determine the temperature dependence of the rate constants. Sequential oxidation reactions of the Ce(x)O(y)⁻ (x = 2, 3) suboxide cluster anions were found to exhibit anti-Arrhenius behavior, with activation energies ranging from 0 to -18 kJ mol⁻¹. Direct oxidation of species up to y = x was observed, after which, -OD abstraction and D₂O addition reactions were observed. However, the stoichiometric Ce₂O₄⁻ and Ce₃O₆⁻ cluster anions also emerge in reactions between D₂O and the respective precursors, Ce₂O₃D⁻ and Ce₃O₅D₂⁻. Ce₂O₄⁻ and Ce₃O₆⁻ product intensities diminish relative to deuteroxide complex intensities with increasing temperature. The kinetics of these reactions are compared to the kinetics of the previously studied Mo(x)O(y)⁻ and W(x)O(y)⁻ reactions with water, and the possible implications for the reaction mechanisms are discussed.

  18. A crossed molecular beam and ab-initio investigation of the reaction of boron monoxide (BO; X2Σ+) with methylacetylene (CH3CCH; X1A1): competing atomic hydrogen and methyl loss pathways.

    PubMed

    Maity, Surajit; Parker, Dorian S N; Dangi, Beni B; Kaiser, Ralf I; Fau, Stefan; Perera, Ajith; Bartlett, Rodney J

    2013-11-21

    The gas-phase reaction of boron monoxide ((11)BO; X(2)Σ(+)) with methylacetylene (CH3CCH; X(1)A1) was investigated experimentally using crossed molecular beam technique at a collision energy of 22.7 kJ mol(-1) and theoretically using state of the art electronic structure calculation, for the first time. The scattering dynamics were found to be indirect (complex forming reaction) and the reaction proceeded through the barrier-less formation of a van-der-Waals complex ((11)BOC3H4) followed by isomerization via the addition of (11)BO(X(2)Σ(+)) to the C1 and/or C2 carbon atom of methylacetylene through submerged barriers. The resulting (11)BOC3H4 doublet radical intermediates underwent unimolecular decomposition involving three competing reaction mechanisms via two distinct atomic hydrogen losses and a methyl group elimination. Utilizing partially deuterated methylacetylene reactants (CD3CCH; CH3CCD), we revealed that the initial addition of (11)BO(X(2)Σ(+)) to the C1 carbon atom of methylacetylene was followed by hydrogen loss from the acetylenic carbon atom (C1) and from the methyl group (C3) leading to 1-propynyl boron monoxide (CH3CC(11)BO) and propadienyl boron monoxide (CH2CCH(11)BO), respectively. Addition of (11)BO(X(2)Σ(+)) to the C1 of methylacetylene followed by the migration of the boronyl group to the C2 carbon atom and/or an initial addition of (11)BO(X(2)Σ(+)) to the sterically less accessible C2 carbon atom of methylacetylene was followed by loss of a methyl group leading to the ethynyl boron monoxide product (HCC(11)BO) in an overall exoergic reaction (78 ± 23 kJ mol(-1)). The branching ratios of these channels forming CH2CCH(11)BO, CH3CC(11)BO, and HCC(11)BO were derived to be 4 ± 3%, 40 ± 5%, and 56 ± 15%, respectively; these data are in excellent agreement with the calculated branching ratios using statistical RRKM theory yielding 1%, 38%, and 61%, respectively. PMID:23651442

  19. A crossed molecular beam and ab-initio investigation of the reaction of boron monoxide (BO; X2Σ+) with methylacetylene (CH3CCH; X1A1): competing atomic hydrogen and methyl loss pathways.

    PubMed

    Maity, Surajit; Parker, Dorian S N; Dangi, Beni B; Kaiser, Ralf I; Fau, Stefan; Perera, Ajith; Bartlett, Rodney J

    2013-11-21

    The gas-phase reaction of boron monoxide ((11)BO; X(2)Σ(+)) with methylacetylene (CH3CCH; X(1)A1) was investigated experimentally using crossed molecular beam technique at a collision energy of 22.7 kJ mol(-1) and theoretically using state of the art electronic structure calculation, for the first time. The scattering dynamics were found to be indirect (complex forming reaction) and the reaction proceeded through the barrier-less formation of a van-der-Waals complex ((11)BOC3H4) followed by isomerization via the addition of (11)BO(X(2)Σ(+)) to the C1 and/or C2 carbon atom of methylacetylene through submerged barriers. The resulting (11)BOC3H4 doublet radical intermediates underwent unimolecular decomposition involving three competing reaction mechanisms via two distinct atomic hydrogen losses and a methyl group elimination. Utilizing partially deuterated methylacetylene reactants (CD3CCH; CH3CCD), we revealed that the initial addition of (11)BO(X(2)Σ(+)) to the C1 carbon atom of methylacetylene was followed by hydrogen loss from the acetylenic carbon atom (C1) and from the methyl group (C3) leading to 1-propynyl boron monoxide (CH3CC(11)BO) and propadienyl boron monoxide (CH2CCH(11)BO), respectively. Addition of (11)BO(X(2)Σ(+)) to the C1 of methylacetylene followed by the migration of the boronyl group to the C2 carbon atom and/or an initial addition of (11)BO(X(2)Σ(+)) to the sterically less accessible C2 carbon atom of methylacetylene was followed by loss of a methyl group leading to the ethynyl boron monoxide product (HCC(11)BO) in an overall exoergic reaction (78 ± 23 kJ mol(-1)). The branching ratios of these channels forming CH2CCH(11)BO, CH3CC(11)BO, and HCC(11)BO were derived to be 4 ± 3%, 40 ± 5%, and 56 ± 15%, respectively; these data are in excellent agreement with the calculated branching ratios using statistical RRKM theory yielding 1%, 38%, and 61%, respectively.

  20. Threshold collision-induced dissociation of hydrated magnesium: experimental and theoretical investigation of the binding energies for Mg(2+)(H2O)x complexes (x=2-10).

    PubMed

    Carl, Damon R; Armentrout, Peter B

    2013-03-18

    The sequential bond energies of Mg(2+)(H2O)x complexes, in which x=2-10, are measured by threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer. From an electrospray ionization source that produces an initial distribution of Mg(2+)(H2O)x complexes in which x=7-10, complexes down to x=3 are formed by using an in-source fragmentation technique. Complexes smaller than Mg(2+)(H2O)3 cannot be formed in this source because charge separation into MgOH(+)(H2O) and H3O(+) is a lower-energy pathway than simple water loss from Mg(2+)(H2O)3. The kinetic energy dependent cross sections for dissociation of Mg(2+)(H2O)x complexes, in which x=3-10, are examined over a wide energy range to monitor all dissociation products and are modeled to obtain 0 and 298 K binding energies. Analysis of both primary and secondary water molecule losses from each sized complex provides thermochemistry for the sequential hydration energies of Mg(2+) for x=2-10 and the first experimental values for x=2-4. Additionally, the thermodynamic onsets leading to the charge-separation products from Mg(2+)(H2O)3 and Mg(2+)(H2O)4 are determined for the first time. Our experimental results for x=3-7 agree well with quantum chemical calculations performed here and previously calculated binding enthalpies, as well as previous measurements for x=6. The present values for x=7-10 are slightly lower than previous experimental results and theory, but within experimental uncertainties.

  1. Identification of the C 2∏-X 2Σ + band system of AlO in the ultraviolet galvanoluminescence obtained during aluminum anodization

    NASA Astrophysics Data System (ADS)

    Sarvan, Mirjana; Perić, Miljenko; Zeković, Ljubiša; Stojadinović, Stevan; Belča, Ivan; Petković, Marija; Kasalica, Bećko

    2011-10-01

    The first galvanoluminescence spectrum in the ultraviolet region obtained during anodization of high purity aluminum samples annealed at temperature above 525 °C is presented. An intense broad peak with the maximum at about 31,900 cm -1 is assigned to the transitions (some of them heretofore unobserved) between vibrational levels of the C 2∏ → X 2Σ + spectral system of AlO, partly overlapped with the A 2Σ + → X 2∏ system of OH.

  2. Properties of ATP-gated ion channels assembled from P2X2 subunits in mouse cochlear Reissner's membrane epithelial cells.

    PubMed

    Morton-Jones, Rachel T; Vlajkovic, Srdjan M; Thorne, Peter R; Cockayne, Debra A; Ryan, Allen F; Housley, Gary D

    2015-12-01

    In the cochlea, Reissner's membrane separates the scala media endolymphatic compartment that sustains the positive endocochlear potential and ion composition necessary for sound transduction, from the scala vestibuli perilymphatic compartment. It is known that with sustained elevated sound levels, adenosine 5'-triphosphate (ATP) is released into the endolymph and ATP-gated ion channels on the epithelial cells lining the endolymphatic compartment shunt the electrochemical driving force, contributing to protective purinergic hearing adaptation. This study characterises the properties of epithelial cell P2X(2)-type ATP-activated membrane conductance in the mouse Reissner's membrane, which forms a substantial fraction of the scale media surface. The cells were found to express two isoforms (a and b) of the P2X(2) subunit arising from alternative splicing of the messenger RNA (mRNA) transcript that could contribute to the trimeric subunit assembly. The ATP-activated conductance demonstrated both immediate and delayed desensitisation consistent with incorporation of the combination of P2X(2) subunit isoforms. Activation by the ATP analogue 2meSATP had equipotency to ATP, whereas α,β-meATP and adenosine 5'-diphosphate (ADP) were ineffective. Positive allosteric modulation of the P2X(2) channels by protons was profound. This native conductance was blocked by the P2X(2)-selective blocker pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) and the conductance was absent in these cells isolated from mice null for the P2rX2 gene encoding the P2X(2) receptor subunit. The activation and desensitisation properties of the Reissner's membrane epithelial cell ATP-gated P2X(2) channels likely contribute to the sensitivity and kinetics of purinergic control of the electrochemical driving force for sound transduction invoked by noise exposure.

  3. Electronic spectrum of C 6H: 2Π- X2Π in the gas-phase detected by cavity ringdown

    NASA Astrophysics Data System (ADS)

    Kotterer, Markus; Maier, John P.

    1997-02-01

    The 2Π- X2Π electronic transition of the carbon chain C 6H has been detected in the gas-phase. The radical is generated in a hollow cathode discharge of acetylene in helium, and cavity ringdown spectroscopy is used as a sensitive means to observed the band system in absorption. This is the first result aimed at locating the electronic transitions of the neutral carbon chains, of astrophysical interest, in the gas-phase. The search was based on the measurements made previously on C 6H in neon matrices. The origin band ( Ω = 3/2) in the gas phase at 18996.4 cm -1 is 142 cm -1 to the blue of the matrix value.

  4. Calculated hydroxyl A2 sigma --> X2 pi (0, 0) band emission rate factors applicable to atmospheric spectroscopy

    NASA Technical Reports Server (NTRS)

    Cageao, R. P.; Ha, Y. L.; Jiang, Y.; Morgan, M. F.; Yung, Y. L.; Sander, S. P.

    1997-01-01

    A calculation of the A2 sigma --> X2 pi (0, 0) band emission rate factors and line center absorption cross sections of OH applicable to its measurement using solar resonant fluorescence in the terrestrial atmosphere is presented in this paper. The most accurate available line parameters have been used. Special consideration has been given to the solar input flux because of its highly structured Fraunhofer spectrum. The calculation for the OH atmospheric emission rate factor in the solar resonant fluorescent case is described in detail with examples and intermediate results. Results of this calculation of OH emission rate factors for individual rotational lines are on average 30% lower than the values obtained in an earlier work.

  5. 60-GHz optical/wireless MIMO system integrated with optical subcarrier multiplexing and 2x2 wireless communication.

    PubMed

    Lin, Chi-Hsiang; Lin, Chun-Ting; Huang, Hou-Tzu; Zeng, Wei-Siang; Chiang, Shou-Chih; Chang, Hsi-Yu

    2015-05-01

    This paper proposes a 2x2 MIMO OFDM Radio-over-Fiber scheme based on optical subcarrier multiplexing and 60-GHz MIMO wireless transmission. We also schematically investigated the principle of optical subcarrier multiplexing, which is based on a dual-parallel Mach-Zehnder modulator (DP-MZM). In our simulation result, combining two MIMO OFDM signals to drive DP-MZM gives rise to the PAPR augmentation of less than 0.4 dB, which mitigates nonlinear distortion. Moreover, we applied a Levin-Campello bit-loading algorithm to compensate for the uneven frequency responses in the V-band. The resulting system achieves OFDM signal rates of 61.5-Gbits/s with BER of 10(-3) over 25-km SMF transmission followed by 3-m wireless transmission.

  6. Theoretical study of the AlO blue-green (B2Sigma + - X2Sigma +) band system

    NASA Technical Reports Server (NTRS)

    Partridge, H.; Langhoff, S. R.; Lengsfield, B. H., III; Liu, B.

    1983-01-01

    Two independent, extensive theoretical calculations are reported for the relative band strengths of the AlO (B2Sigma + - X2Sigma +) blue-green system and for the radiative lifetimes of the lowest few vibrational levels of the B2Sigma(+) state. The theoretical lifetimes, which include a small (less than -.5 percent) contribution from bound-bound transitions into the A2Pi state, are in excellent agreement with laser fluorescence studies. The theoretical lifetimes increase monotonically and very slowly with increasing vibrational quantum number. The relative band strengths for the blue-green system derived from the two theoretical calculations are in excellent agreement, but differ systematically from the relative band strengths of Linton and Nicholls (1969). The present results suggest that their self-absorption corrections are not large enough, resulting in relative intensities that are too large, especially for the weak bands with r centroids less than 1.5 A.

  7. High resolution absorption cross sections for the A2Pi-X2Pi system of ClO

    NASA Technical Reports Server (NTRS)

    Wine, P. H.; Ravishankara, A. R.; Philen, D. L.; Davis, D. D.; Watson, R. T.

    1977-01-01

    High-resolution ultraviolet absorption cross-sections for the ClO molecule are obtained, with the aim of facilitating studies of ozone depletion resulting from the injection of chlorofluorocarbons into the atmosphere. The spectroscopic analysis, which involves a frequency-doubled tunable dye laser with a bandwidth of 0.015 A, is described. Studies of the rotational lines of the ClO A 2Pi 3/2-X2Pi 3/2 9-10 band were conducted. Peak cross-sections for the P and R lines of the 9-0 band are found to be 10.0, 9.6, 8.6, 10.6, 10.3, and 9.2 times ten to the negative seventeenth power cm squared, with estimated accuracy of plus or minus 25%. Problems in distinguishing between Cl-35 and Cl-37 absorption are also considered.

  8. OH(A 2Sigma(+) - X 2Pi) emission from dissociative excitation of HO2 at 147 nm

    NASA Astrophysics Data System (ADS)

    Suto, M.; Lee, L. C.

    1984-01-01

    The photodissociation processes of the HO2 radical have been studied using the Xe resonance line at 147 nm as a light source. HO2 radical was produced by the reaction H + O2 + He HO2 + He in a flow tube, and the HO2 concentration was measured by a titration method HO2 + NO - OH + NO2. An observed emission in the 310 + or -10 nm region was found to be due solely to photodissociation and is attributed to the OH(A 2Sigma(+) - X 2Pi) system. This emission was studied as a function of O2 and H2 pressure added to the flow tube. Other possible photoemission processes were considered, including photoexcitation of OH, photodissociative excitation of H2O2, emission from the reaction O(D-1) + H, and metastable O2 produced from photodissociation of HO2. It is concluded that the emission intensities produced from these processes is negligible.

  9. Integration of multiple data sets for resource evaluation of the Montrose 1/sup 0/ x 2/sup 0/ Quadrangle, Colorado

    SciTech Connect

    Balog, S.H.; Bolivar, S.L.; Weaver, T.A.

    1981-01-01

    At Los Alamos National Laboratory, geoscientists have assembled and integrated 30 geological, geochemical, and geophysical data sets with 4 Landsat bands for the Montrose 1/sup 0/ x 2/sup 0/ quadrangle, Colorado. A graphical presentation, which allows three data sets to be viewed simultaneously, is employed to facilitate the interpretation. Analysis of one of the three-data-set combinations (copper, lead, zinc) defines, spatially and geochemically, all the mining districts in the quadrangle and yields new information relating to base and precious metal mineralization. Analysis of two other three-data-set combinations (dysprosium, hafnium, scandium; and potassium, lithium, titanium) indicates that the granites in the Sawatch Range are of different trace-element composition (and therefore, possibly of different origin) than the granites in the Mosquito Range. This technique permits rapid analysis of tremendous amounts of data and the inference of correlative information that is not inherent in single data sets.

  10. Density functional theory calculations of magnetocrystalline anisotropy energies for (Fe(1-x)Co(x))(2)B.

    PubMed

    Däne, Markus; Kim, Soo Kyung; Surh, Michael P; Åberg, Daniel; Benedict, Lorin X

    2015-07-01

    We present and discuss density functional theory calculations of magnetic properties of the family of ferromagnetic compounds, (Fe(1-x)Co(x))(2)B, focusing specifically on the magnetocrystalline anisotropy energy (MAE). Using periodic supercells of various sizes (up to 96 atoms), it is shown that the general qualitative features of the composition dependence of the MAE is in agreement with experimental findings, while our predicted magnitudes are larger than those of experiment. We find that the use of small supercells (6 and 12-atom) favors larger MAE values relative to a statistical sample of configurations constructed with 96-atom supercells. The effect of lattice relaxations is shown to be small. Calculations of the Curie temperature for this alloy are also presented.

  11. Rotational Tunnelling in Methyl Metal Compounds X2(CH3)4 with X = As, Sb, Bi

    NASA Astrophysics Data System (ADS)

    Kuhnen, A.; Müller-Warmuth, W.; Prager, M.; Mündt, O.; Reti, M.; Becker, G.

    1997-04-01

    Rotational excitations of methyl groups attached to metal atoms of the fifth main group have been investigated in X2(CH3)4 crystals with X = As, Sb, Bi by 1H nuclear magnetic resonance (NMR) relaxation measurements and inelastic neutron scattering (INS). CH3 rotation has been found to be rather weakly hindered (activation energies between 1.7 kJ/mol and 5.8 kJ/mol) so that quantum effects are important to describe the results. Tunnel splittings between 0.1 μeV and 23 μeV have been observed. Non-equivalent methyl groups in tetramethyldistibane and tetramethyldibismuthane have been identified by both INS and NMR. A consistent description of the T1 data is possible by Haupt's equation. The rotational potentials could be derived and relations to the crystal structure have been discussed.

  12. FOUR WAVE MIXING SPECTROSCOPY OF THE NO_3 tilde{B} ^2E' - tilde{X} ^2A_2' transition

    NASA Astrophysics Data System (ADS)

    Fukushima, Masaru; Ishiwata, Takashi

    2014-06-01

    The tilde{B} ^2E' - tilde{X} ^2A_2' electronic transition of NO_3 generated in a supersonic free jet expansion was investigated by four wave mixing ( 4WM ) spectroscopy. The degenerated 4WM and laser induced fluorescence ( LIF ) spectra around the 0_0^0 band region were measured simultaneously. The D4WM spectrum shows broad band features for the 0_0^0 band similar to that of the LIF spectrum. The broad 0_0^0 band does not consist of one sub-band, but of several bands. The intensity distribution of the sub-bands of the D4WM spectrum is similar, but not identical to that of the LIF spectrum.

  13. Mechanisms of the Lscript 2Φ-X 2Π emission of NO in Ar and Kr matrices

    NASA Astrophysics Data System (ADS)

    Chergui, Majed; Schwentner, Nikolaus; Chandrasekharan, Venkataraman

    1988-12-01

    New time and energy resolved spectra of the L' 2Φ-X 2Π (0,v″) bands of NO in Ar and Kr matrices are reported. The L'(0,v″) bands are excited exclusively via the B' 2Δ valence state and their lifetime is 3000±500 ns in both matrices. The quantum efficiency for L'(v=0) emission is estimated to be ≤0.04. The 2Φ-2Π transition is discussed in terms of a statically induced transition moment involving spin-orbit mixing with B' 2Δ, but also in terms of nonadiabatic matrix elements due to the coupling to the lattice. Relaxation down to L'(v=0) is discussed in terms of matrix-induced interstate cascading with the b 4Σ- state.

  14. Metal-insulator transition in variably doped (Bi(1-x)Sb(x))2Se3 nanosheets.

    PubMed

    Lee, Chee Huei; He, Rui; Wang, ZhenHua; Qiu, Richard L J; Kumar, Ajay; Delaney, Conor; Beck, Ben; Kidd, T E; Chancey, C C; Sankaran, R Mohan; Gao, Xuan P A

    2013-05-21

    Topological insulators are novel quantum materials with metallic surface transport but insulating bulk behavior. Often, topological insulators are dominated by bulk contributions due to defect induced bulk carriers, making it difficult to isolate the more interesting surface transport characteristics. Here, we report the synthesis and characterization of nanosheets of a topological insulator Bi2Se3 with variable Sb-doping levels to control the electron carrier density and surface transport behavior. (Bi(1-x)Sb(x))2Se3 thin films of thickness less than 10 nm are prepared by epitaxial growth on mica substrates in a vapor transport setup. The introduction of Sb in Bi2Se3 effectively suppresses the room temperature electron density from ∼4 × 10(13) cm(-2) in pure Bi2Se3 (x = 0) to ∼2 × 10(12) cm(-2) in (Bi(1-x)Sb(x))2Se3 at x ∼ 0.15, while maintaining the metallic transport behavior. At x ≳ ∼0.20, a metal-insulator transition (MIT) is observed, indicating that the system has transformed into an insulator in which the metallic surface conduction is blocked. In agreement with the observed MIT, Raman spectroscopy reveals the emergence of vibrational modes arising from Sb-Sb and Sb-Se bonds at high Sb concentrations, confirming the appearance of the Sb2Se3 crystal structure in the sample. These results suggest that nanostructured chalcogenide films with controlled doping can be a tunable platform for fundamental studies and electronic applications of topological insulator systems. PMID:23563061

  15. Double P2X2/P2X3 Purinergic Receptor Knockout Mice Do Not Taste NaCl or the Artificial Sweetener SC45647

    PubMed Central

    Eddy, Meghan C.; Eschle, Benjamin K.; Barrows, Jennell; Hallock, Robert M.; Finger, Thomas E.

    2009-01-01

    The P2X ionotropic purinergic receptors, P2X2 and P2X3, are essential for transmission of taste information from taste buds to the gustatory nerves. Mice lacking both P2X2 and P2X3 purinergic receptors (P2X2/P2X3Dbl−/−) exhibit no taste-evoked activity in the chorda tympani and glossopharyngeal nerves when stimulated with taste stimuli from any of the 5 classical taste quality groups (salt, sweet, sour, bitter, and umami) nor do the mice show taste preferences for sweet or umami, or avoidance of bitter substances (Finger et al. 2005. ATP signaling is crucial for communication from taste buds to gustatory nerves. Science. 310[5753]:1495–1499). Here, we compare the ability of P2X2/P2X3Dbl−/− mice and P2X2/P2X3Dbl+/+ wild-type (WT) mice to detect NaCl in brief-access tests and conditioned aversion paradigms. Brief-access testing with NaCl revealed that whereas WT mice decrease licking at 300 mM and above, the P2X2/P2X3Dbl−/− mice do not show any change in lick rates. In conditioned aversion tests, P2X2/P2X3Dbl−/− mice did not develop a learned aversion to NaCl or the artificial sweetener SC45647, both of which are easily avoided by conditioned WT mice. The inability of P2X2/P2X3Dbl−/− mice to show avoidance of these taste stimuli was not due to an inability to learn the task because both WT and P2X2/P2X3Dbl−/− mice learned to avoid a combination of SC45647 and amyl acetate (an odor cue). These data suggest that P2X2/P2X3Dbl−/− mice are unable to respond to NaCl or SC45647 as taste stimuli, mirroring the lack of gustatory nerve responses to these substances. PMID:19833661

  16. Anisotropic thermoelectric properties of layered compounds in SnX2 (X = S, Se): a promising thermoelectric material.

    PubMed

    Sun, Bao-Zhen; Ma, Zuju; He, Chao; Wu, Kechen

    2015-11-28

    Thermoelectrics interconvert heat to electricity and are of great interest in waste heat recovery, solid-state cooling and so on. Here we assessed the potential of SnS2 and SnSe2 as thermoelectric materials at the temperature gradient from 300 to 800 K. Reflecting the crystal structure, the transport coefficients are highly anisotropic between a and c directions, in particular for the electrical conductivity. The preferred direction for both materials is the a direction in TE application. Most strikingly, when 800 K is reached, SnS2 can show a peak power factor (PF) of 15.50 μW cm(-1) K(-2) along the a direction, while a relatively low value (11.72 μW cm(-1) K(-2)) is obtained in the same direction of SnSe2. These values are comparable to those observed in thermoelectrics such as SnSe and SnS. At 300 K, the minimum lattice thermal conductivity (κmin) along the a direction is estimated to be about 0.67 and 0.55 W m(-1) K(-1) for SnS2 and SnSe2, respectively, even lower than the measured lattice thermal conductivity of Bi2Te3 (1.28 W m(-1) K(-1) at 300 K). The reasonable PF and κmin suggest that both SnS2 and SnSe2 are potential thermoelectric materials. Indeed, the estimated peak ZT can approach 0.88 for SnSe2 and a higher value of 0.96 for SnS2 along the a direction at a carrier concentration of 1.94 × 10(19) (SnSe2) vs. 2.87 × 10(19) cm(-3) (SnS2). The best ZT values in SnX2 (X = S, Se) are comparable to that in Bi2Te3 (0.8), a typical thermoelectric material. We hope that this theoretical investigation will provide useful information for further experimental and theoretical studies on optimizing the thermoelectric properties of SnX2 materials.

  17. A series of new manganese thioarsenates(v) based on different unsaturated [Mn(amine)x](2+) complexes.

    PubMed

    Zhou, Jian; Tan, Xiao-Feng; Liu, Xing; Qing, Miao; Zhao, Rong-Qing; Tang, Qiuling

    2015-10-01

    A series of new manganese thioarsenates(V) [Mn(en)2Cu(AsVS4)]n (1, en = ethylenediamine), [Mn(dien)2][Mn(dien)(AsVS4)]2 (2, dien = diethylenetriamine), [Mn(teta)(AsVS4)]n (3, teta = triethylenetetramine), and {[Mn(dap)2][Mn(dap)(AsVS4)]2}n (4, dap = 1,2-diaminopropane) have been solvothermally synthesized and structurally characterized. 1 displays a neutral heterometallic [Mn(en)2Cu(AsVS4)]n chain built up from the linkages of [Mn(en)2]2+ complexes and infinite heterometallic [Cu(AsVS4)2−]n chains, and represents the only example of incorporation of an unsaturated [Mn(en)2]2+ complex into the 1-D [Cu(AsVS4)2−]n framework. 2 consists of a discrete {[Mn(dien)]2(AsVS4)2}2− cluster and a charge compensating complex cation [Mn(dien)2]2+. 3 shows a 1-D neutral [Mn(teta)(AsVS4)]n chain constructed by the combination of both complex [Mn(teta)]2+ ions and tetrahedral [AsVS4]3− anions. 4 exhibits a rare 2-D {[Mn(dap)2][Mn(dap)(AsVS4)]2}n layer based on the linkages of [AsVS4]3− anions and [Mn(dap)x]2+ (x = 1, 2) groups. These results show that different unsaturated [Mn(amine)x]2+ complexes are directly bonded to [AsVS4]3− anions to give different manganese thioarsenates(V), which have a significant structure directing effect on the structures of manganese thioarsenates(V) under similar solvothermal conditions. The present compounds exhibit wide-band-gap semiconducting properties with absorption band edges between 2.00 and 2.58 eV, and density functional theory calculations for compounds 1, 3 and 4 have also been performed.

  18. Born-Oppenheimer and Renner-Teller Quantum Dynamics of CH(X(2)Π) + D((2)S) Reactions on Three CHD Potential Surfaces.

    PubMed

    Gamallo, Pablo; Akpinar, Sinan; Defazio, Paolo; Petrongolo, Carlo

    2015-11-19

    The quantum dynamics of three CH(X(2)Π) + D((2)S) reactions is studied by means of the coupled-channel time-dependent real-wavepacket (WP) and flux methods at collision energy Ecol ≤ 0.6 eV and on three potential energy surfaces (PESs): the Born-Oppenheimer (BO) ground PES X̃(3)A″ and the excited ones ã(1)A' and b̃(1)A″, coupled by nonadiabatic (NA) Renner-Teller (RT) effects. This three-state model is suitable for obtaining initial-state-resolved observables, is based on a complete analysis of the correlation diagram of the lowest electronic states of the CHD intermediate and of their NA interactions, and neglects the smaller coupling effects due to the asymptotic electronic angular momenta that become important in state-to-state dynamics. WPs are propagated on each PES at total angular momentum values J ≤ 70, with CH in the two lowest vibrational states v0 and in the ground rotational state j0 = 1. Reaction probabilities are obtained for three possible final products (f): (dP) CH decay and C((3)P) + HD(X(1)Σ(+)) formation that occurs on the uncoupled ground PES, (dD) CH decay and C((1)D) + HD(X(1)Σ(+)) formation that depends on the RT-coupled singlet species, and (ex) exchange to CD(X(2)Π) + H((2)S) available adiabatically from the X̃(3)A″ PES and nonadiabatically from ã(1)A' and b̃(1)A″. Observable cross sections σf,v0j0 and rate constants kf,v0j0 in the temperature range T = 100-2000 K are obtained for (dP), (dD), and (ex) channels. Comparing BO with RT probabilities, we show that NA effects are important at high J values for the (ex) channel at v0 = 1. Real time mechanisms on the three PESs show that RT couplings are opened after some time and clearly point out the formation of the product channels. Both cross sections and rate constants present the same sequence, for example σex,11 > σdP,01 ∼ σex,01 > σdP,11 ≫ σdD,11 ≫ σdD,01, and the CH vibrational excitation enhances the total removal CH+D reactivity by a factor of ∼1

  19. Deletion of P2X2 and P2X3 Receptor Subunits Does Not Alter Motility of the Mouse Colon

    PubMed Central

    DeVries, Matthew P.; Vessalo, Megan; Galligan, James J.

    2010-01-01

    Purinergic P2X receptors contribute to neurotransmission in the gut. P2X receptors are ligand-gated cation channels that mediate synaptic excitation in subsets of enteric neurons. The present study evaluated colonic motility in vitro and in vivo in wild type (WT) and P2X2 and P2X3 subunit knockout (KO) mice. The muscarinic receptor agonist, bethanechol (0.3–3 μM), caused similar contractions of the longitudinal muscle in colon segments from WT, P2X2 and P2X3 subunit KO mice. Nicotine (1–300 μM), acting at neuronal nicotinic receptors, caused similar longitudinal muscle relaxations in colonic segments from WT and P2X2 and P2X3 subunit KO mice. Nicotine-induced relaxations were inhibited by nitro-l-arginine (NLA, 100 μM) and apamin (0.1 μM) which block inhibitory neuromuscular transmission. ATP (1–1000 μM) caused contractions only in the presence of NLA and apamin. ATP-induced contractions were similar in colon segments from WT, P2X2 and P2X3 KO mice. The mouse colon generates spontaneous migrating motor complexes (MMCs) in vitro. The MMC frequency was higher in P2X2 KO compared to WT tissues; other parameters of the MMC were similar in colon segments from WT, P2X2 and P2X3 KO mice. 5-Hydroxytryptophan-induced fecal output was similar in WT, P2X2 and P2X3 KO mice. These data indicate that nicotinic receptors are located predominately on inhibitory motor neurons supplying the longitudinal muscle in the mouse colon. P2X2 or P2X3 subunit containing receptors are not localized to motor neurons supplying the longitudinal muscle. Synaptic transmission mediated by P2X2 or P2X3 subunit containing receptors is not required for propulsive motility in the mouse colon. PMID:20582262

  20. Tri-icosahedral Gold Nanocluster [Au37(PPh3)10(SC2H4Ph)10X2](+): Linear Assembly of Icosahedral Building Blocks.

    PubMed

    Jin, Renxi; Liu, Chong; Zhao, Shuo; Das, Anindita; Xing, Hongzhu; Gayathri, Chakicherla; Xing, Yan; Rosi, Nathaniel L; Gil, Roberto R; Jin, Rongchao

    2015-08-25

    The [Au37(PPh3)10(SR)10X2](+) nanocluster (where SR = thiolate and X = Cl/Br) was theoretically predicted in 2007, but since then, there has been no experimental success in the synthesis and structure determination. Herein, we report a kinetically controlled, selective synthesis of [Au37(PPh3)10(SC2H4Ph)10X2](+) (counterion: Cl(-) or Br(-)) with its crystal structure characterized by X-ray crystallography. This nanocluster shows a rod-like structure assembled from three icosahedral Au13 units in a linear fashion, consistent with the earlier prediction. The optical absorption and the electrochemical and catalytic properties are investigated. The successful synthesis of this new nanocluster allows us to gain insight into the size, structure, and property evolution of gold nanoclusters that are based upon the assembly of icosahedral units (i.e., cluster of clusters). Some interesting trends are identified in the evolution from the monoicosahedral [Au13(PPh3)10X2](3+) to the bi-icosahedral [Au25(PPh3)10(SC2H4Ph)5X2](2+) and to the tri-icosahedral [Au37(PPh3)10(SC2H4Ph)10X2](+) nanocluster, which also points to the possibility of achieving even longer rod nanoclusters based upon assembly of icosahedral building blocks. PMID:26214221

  1. Chemical abundances of the secondary star in the neutron star X-ray binary Cygnus X-2

    NASA Astrophysics Data System (ADS)

    Suárez-Andrés, L.; González Hernández, J. I.; Israelian, G.; Casares, J.; Rebolo, R.

    2015-03-01

    We present Utrecht Echelle Spectrograph@William Herschel Telescope high-resolution spectra of the low-mass X-ray binary (LMXB) Cygnus X-2. We have derived the stellar parameters of the secondary star using χ2 minimization procedure, and taking into account any possible veiling from the accretion disc. We determine a metallicity higher than solar ([Fe/H] = 0.27 ± 0.19), as seen also in the neutron star X-ray binary Centaurus X-4. The high quality of the secondary's spectrum allow us to determine the chemical abundances of O, Mg, Si, Ca, S, Ti, Fe, and Ni. We found that some α-elements (Mg, Si, S, Ti) are enhanced, consistent with a scenario of contamination of the secondary star during the supernova event. Surprisingly oxygen appears to be underabundant, whereas enhanced abundances of Fe and Ni are measured. Assuming that these abundances come from matter that has been processed in the SN and then captured by the secondary star, we explore different SN explosion scenarios with diverse geometries. A non-spherically symmetric SN explosion, with a low mass cut, seems to reproduce better the observed abundance pattern of the secondary star compared to the spherical case.

  2. Resource characterization for uranium mineralization in the Montrose 1/sup 0/ x 2/sup 0/ quadrangle, Colorado

    SciTech Connect

    Bolivar, S.L.; Balog, S.H.; Weaver, T.A.

    1981-01-01

    A data-classification scheme was developed to detect potential uranium mineralization in the Montrose 1/sup 0/ x 2/sup 0/ quadrangle, Colorado. The methodology developed is a rapid and efficient method of resource evaluation on a reconnaissance scale. The necessary techniques were developed and refined to digitize, integrate, and register various large geological, geochemical, and geophysical data sets for the Montrose quadrangle, Colorado, using a grid resolution of 1 km. All data sets for the Montrose quadrangle were registered to the Universal Transverse Mercator projection. The data sets include hydrogeochemical and stream sediment analyses for 23 elements, uranium-to-thorium ratios, airborne geophysical survey data, the locations of 90 uranium occurrences, and a geologic map (scale 1:250 000). Geochemical samples were collected from 3965 locations in the 19 200 km/sup 2/ quadrangle; aerial data were collected on flight lines flown with 3 to 5 km spacings. These data sets were smoothed by universal kriging and interpolated to a 179 x 119 rectangular grid (each grid block is 1 km/sup 2/). A mylar transparency of the geologic map was prepared and digitized. All possible combinations of three, for all data sets, were examined for general geologic correlations by utilizing a color microfilm output. Subsets of data were further examined for selected test areas. A classification scheme for uranium mineralization, based on selected test areas in the Cochetopa uranium district, is presented. Areas favorable for uranium mineralization, based on this scheme, were identified and are discussed.

  3. Li(x)FeF6 (x = 2, 3, 4) battery materials: structural, electronic and lithium diffusion properties.

    PubMed

    Schroeder, Melanie; Eames, Christopher; Tompsett, David A; Lieser, Georg; Islam, M Saiful

    2013-12-21

    Lithium iron fluoride materials have attracted recent interest as cathode materials for lithium ion batteries. The electrochemical properties of the high energy density Li(x)FeF6 (x = 2, 3, 4) materials have been evaluated using a combination of potential-based and DFT computational methods. Voltages of 6.1 V and 3.0 V are found for lithium intercalation from Li2FeF6 to α-Li3FeF6 and α-Li3FeF6 to Li4FeF6 respectively. The calculated density of states indicate that Li2FeF6 possesses metallic states that become strongly insulating after lithium intercalation to form α-Li3FeF6. The large energy gain associated with this metal-insulator transition is likely to contribute to the associated large voltage of 6.1 V. Molecular dynamics simulations of lithium diffusion in α-Li3FeF6 at typical battery operating temperatures indicate high lithium-ion mobility with low activation barriers. These results suggest the potential for good rate performance of lithium iron fluoride cathode materials.

  4. Temperature dependent EXAFS study on transition metal dichalcogenides MoX2 (X  =  S, Se, Te).

    PubMed

    Caramazza, S; Marini, C; Simonelli, L; Dore, P; Postorino, P

    2016-08-17

    The local structure of molybdenum dichalcogenide MoX2 (X  =  S, Se, Te) single crystal has been studied by means of multi-edge (Mo, Se, and Te K-edges) extended x-ray absorption fine-structure spectroscopy as function of temperature. The temperature dependences of the interatomic distances Mo-X, Mo-Mo and X-X (X  =  S, Se, and Te) and of the corresponding Debye-Waller factors have been extracted over the 70-500 K temperature range. Exploiting the correlated Einstein model, we found that the Einstein frequencies of Mo-X and X-X bonds obtained by present data are in close agreement with the frequencies of the optical (Raman and infrared) stretching modes for both MoS2 and MoSe2, whereas a significant deviation has been found for MoTe2. A similar anomaly has been found for the force constants related to the Mo-X bonds in the MoTe2 case. Our findings, accordingly with the results reported in a recent theoretical paper, support the idea that the optical vibrational modes have a dominant role in MoS2 and MoSe2, whereas the effects of acoustic vibrational modes cannot be neglected in the case of MoTe2. PMID:27345937

  5. Photoelectron diffraction k-space volumes of the c(2x2) Mn/Ni(100) structure

    SciTech Connect

    Banerjee, S.; Denlinger, J.; Chen, X.

    1997-04-01

    Traditionally, x-ray photoelectron diffraction (XPD) studies have either been done by scanning the diffraction angle for fixed kinetic energy (ADPD), or scanning the kinetic energy at fixed exit angle (EDPD). Both of these methods collect subsets of the full diffraction pattern, or volume, which is the intensity of photoemission as a function of momentum direction and magnitude. With the high density available at the Spectromicroscopy Facility (BL 7.0) {open_quotes}ultraESCA{close_quotes} station, the authors are able to completely characterize the photoelectron diffraction patterns of surface structures, up to several hundred electron volts kinetic energy. This large diffraction `volume` can then be analyzed in many ways. The k-space volume contains as a subset the energy dependent photoelectron diffraction spectra along all emission angles. It also contains individual, hemispherical, diffraction patterns at specific kinetic energies. Other `cuts` through the data set are also possible, revealing new ways of viewing photoelectron diffraction data, and potentially new information about the surface structure being studied. In this article the authors report a brief summary of a structural study being done on the c(2x2) Mn/Ni(100) surface alloy. This system is interesting for both structural and magnetic reasons. Magnetically, the Mn/Ni(100) surface alloy exhibits parallel coupling of the Mn and Ni moments, which is opposite to the reported coupling for the bulk, disordered, alloy. Structurally, the Mn atoms are believed to lie well above the surface plane.

  6. Strain-controlled switch between ferromagnetism and antiferromagnetism in 1 T -Cr X2 (X =Se , Te) monolayers

    NASA Astrophysics Data System (ADS)

    Lv, H. Y.; Lu, W. J.; Shao, D. F.; Liu, Y.; Sun, Y. P.

    2015-12-01

    We report on the strain-induced switch between ferromagnetic (FM) and antiferromagnetic (AFM) orderings in 1 T -Cr X2 (X =Se , Te) monolayers based on first-principles calculations. The CrSe2 and CrTe2 monolayers without strains are found to be AFM and FM, respectively. Under biaxial tensile strain, the CrSe2 monolayer tends to be FM when the strain is larger than 2%. The FM state is further stabilized when the strain is increased. Moreover, the CrSe2 monolayer becomes half metallic when the tensile strain is larger than 10%, while for the CrTe2 monolayer, the critical strain at which the transition between the FM and AFM states occurs is compressive, of -1 % . Relatively small tensile strains of 4% and 2%, respectively, can enhance the Curie temperature of the CrSe2 and CrTe2 monolayers above room temperature. The strain-induced switch between the FM and AFM states in a CrSe2 (CrTe2) monolayer can be understood by the competition between the AFM Cr-Cr direct exchange interaction and the FM Cr-Se(Te)-Cr superexchange interaction. Tunable and attractive magnetic and electronic properties controlled by flexible strain are desirable for future nanoelectronic applications.

  7. Kinetics of thermal reaction HOCl ⇄ H(2 S) + OCl( X 2Π i ) in gas phase

    NASA Astrophysics Data System (ADS)

    Begović, N.; Marković, Z.; Anić, S.

    2011-12-01

    The kinetics of gas reaction HOCl\\underset{{k_r }}{overset{{k_f }}{longleftrightarrow}}H(^2 S) + OCl(X^2 Pi _i ) was analyzed by the MP4 method. In the temperature range of 100-373 K the rate constants k f and k r and equilibrium constant K were changed from 1.10 × 10-220 to 1.17 × 10-52 s-1, from 2.89 × 10-16 to 1.68 × 10-5s-1 and from 3.80 × 10-205 to 6.96 × 10-48 respectively. In the above temperature range, the activation energy of the forward reaction ( E f) is 105.05 kcal/mol. In the same temperature interval there are two kinetic domains for the reverse reaction with activation energies ( E r1 = 5.53 kcal/mol when T is 100-273 K and E r2 = 14.50 kcal/mol when T is 273-373 K, respectively.

  8. Detection of cyclotron resonance scattering feature in high-mass X-ray binary pulsar SMC X-2

    NASA Astrophysics Data System (ADS)

    Jaisawal, Gaurava K.; Naik, Sachindra

    2016-09-01

    We report broad-band spectral properties of the high-mass X-ray binary pulsar SMC X-2 by using three simultaneous Nuclear Spectroscopy Telescope Array and Swift/XRT observations during its 2015 outburst. The pulsar was significantly bright, reaching a luminosity up to as high as ˜5.5 × 1038 erg s-1 in 1-70 keV range. Spin period of the pulsar was estimated to be 2.37 s. Pulse profiles were found to be strongly luminosity dependent. The 1-70 keV energy spectrum of the pulsar was well described with three different continuum models such as (i) negative and positive power law with exponential cutoff, (ii) Fermi-Dirac cutoff power law and (iii) cutoff power-law models. Apart from the presence of an iron line at ˜6.4 keV, a model independent absorption like feature at ˜27 keV was detected in the pulsar spectrum. This feature was identified as a cyclotron absorption line and detected for the first time in this pulsar. Corresponding magnetic field of the neutron star was estimated to be ˜2.3 × 1012 G. The cyclotron line energy showed a marginal negative dependence on the luminosity. The cyclotron line parameters were found to be variable with pulse phase and interpreted as due to the effect of emission geometry or complicated structure of the pulsar magnetic field.

  9. Raman spectroscopy of NiSe2 and NiS2-xSex (0<x<2) thin films

    NASA Astrophysics Data System (ADS)

    de las Heras, C.; Agulló-Rueda, F.

    2000-06-01

    The Raman spectra of NiS2-xSex (0<x<2) polycrystalline thin films have been measured for the first time in the whole x range and for NiSe2. The NiSe2 spectrum is qualitatively similar to the spectrum of NiS2, but all frequencies are shifted to lower energies. The shift has been analysed in terms of the increment of the anion mass and the lattice expansion. Peaks in the Raman spectrum of the NiS2-xSex alloy can be assigned to stretching and rotational modes of the S-S, Se-Se and S-Se pairs. The stretching vibration of the S-Se pairs shifts almost linearly from 400 cm-1 for NiS2 to 330 cm-1 for NiSe2. There is an accidental degeneracy between the S-S stretching and Se-Se libration frequencies. The relative Raman intensities fit well with a random occupation of the anion sites by S and Se atoms, and different scattering cross sections.

  10. Temperature dependent EXAFS study on transition metal dichalcogenides MoX2 (X  =  S, Se, Te).

    PubMed

    Caramazza, S; Marini, C; Simonelli, L; Dore, P; Postorino, P

    2016-08-17

    The local structure of molybdenum dichalcogenide MoX2 (X  =  S, Se, Te) single crystal has been studied by means of multi-edge (Mo, Se, and Te K-edges) extended x-ray absorption fine-structure spectroscopy as function of temperature. The temperature dependences of the interatomic distances Mo-X, Mo-Mo and X-X (X  =  S, Se, and Te) and of the corresponding Debye-Waller factors have been extracted over the 70-500 K temperature range. Exploiting the correlated Einstein model, we found that the Einstein frequencies of Mo-X and X-X bonds obtained by present data are in close agreement with the frequencies of the optical (Raman and infrared) stretching modes for both MoS2 and MoSe2, whereas a significant deviation has been found for MoTe2. A similar anomaly has been found for the force constants related to the Mo-X bonds in the MoTe2 case. Our findings, accordingly with the results reported in a recent theoretical paper, support the idea that the optical vibrational modes have a dominant role in MoS2 and MoSe2, whereas the effects of acoustic vibrational modes cannot be neglected in the case of MoTe2.

  11. Metal-based 1X2 plastic optical fiber (POF) splitter for video over POF system application

    NASA Astrophysics Data System (ADS)

    Ehsan, A. A.; Shaari, S.; Abd Rahman, M. K.

    2009-11-01

    A 1X2 POF splitter based on a Y-branch metal hollow POF coupler design has been developed. The device is composed of three sections: an input POF waveguide, an intermediate hollow waveguide taper and output POF waveguides. Simulation based on non-sequential ray tracings have been performed on the POF splitter. Low cost aluminum based material has been used for the device substrate. Fabrication of the POF splitters are done by producing the device mold insert using high speed CNC machining tool and short POF fibers at the input and output sections are inserted inside the mold insert before the interfaces of the hollow waveguide taper. The POF splitter has an average insertion loss of 5.8 +/- 0.2 dB, excess loss of 2.8 dB and coupling ratio of 1:1. A video-over POF system test-bed consisting of a POF video transmitter and receiver has been constructed with a total transmission length of 10 m. The POF splitter has been tested in the video-over POF system and shows no significant signal degradation.

  12. Temperature dependent EXAFS study on transition metal dichalcogenides MoX2 (X  =  S, Se, Te)

    NASA Astrophysics Data System (ADS)

    Caramazza, S.; Marini, C.; Simonelli, L.; Dore, P.; Postorino, P.

    2016-08-01

    The local structure of molybdenum dichalcogenide MoX2 (X  =  S, Se, Te) single crystal has been studied by means of multi-edge (Mo, Se, and Te K-edges) extended x-ray absorption fine-structure spectroscopy as function of temperature. The temperature dependences of the interatomic distances Mo-X, Mo-Mo and X-X (X  =  S, Se, and Te) and of the corresponding Debye-Waller factors have been extracted over the 70-500 K temperature range. Exploiting the correlated Einstein model, we found that the Einstein frequencies of Mo-X and X-X bonds obtained by present data are in close agreement with the frequencies of the optical (Raman and infrared) stretching modes for both MoS2 and MoSe2, whereas a significant deviation has been found for MoTe2. A similar anomaly has been found for the force constants related to the Mo-X bonds in the MoTe2 case. Our findings, accordingly with the results reported in a recent theoretical paper, support the idea that the optical vibrational modes have a dominant role in MoS2 and MoSe2, whereas the effects of acoustic vibrational modes cannot be neglected in the case of MoTe2.

  13. Vibrationally specific photoionization cross sections of acrolein leading to the tilde{X} {}^2 A^' } ionic state

    NASA Astrophysics Data System (ADS)

    López-Domínguez, Jesús A.; Lucchese, Robert R.; Fulfer, K. D.; Hardy, David; Poliakoff, E. D.; Aguilar, A. A.

    2014-09-01

    The vibrational branching ratios in the photoionization of acrolein for ionization leading to the tilde{X} {}^2 A^' } ion state were studied. Computed logarithmic derivatives of the cross section and the corresponding experimental data derived from measured vibrational branching ratios for several normal modes (ν9, ν10, ν11, and ν12) were found to be in relatively good agreement, particularly for the lower half of the 11-100 eV photon energy range considered. Two shape resonances have been found near photon energies of 15.5 and 23 eV in the photoionization cross section and have been demonstrated to originate from the partial cross section of the A' scattering symmetry. The wave functions computed at the resonance complex energies are delocalized over the whole molecule. By looking at the dependence of the cross section on the different normal mode displacements together with the wave function at the resonant energy, a qualitative explanation is given for the change of the cross sections with respect to changing geometry.

  14. The atomic structure and chemical composition of HfOx (x < 2) films prepared by ion-beam sputtering deposition

    NASA Astrophysics Data System (ADS)

    Aliev, V. S.; Gerasimova, A. K.; Kruchinin, V. N.; Gritsenko, V. A.; Prosvirin, I. P.; Badmaeva, I. A.

    2016-08-01

    Non-stoichiometric HfOx films of different chemical composition (x < 2) were fabricated by ion-beam sputtering deposition (IBSD) at room temperature. The ratio of O and Hf atoms in films x was varied by setting the O2 partial pressure in a chamber. An effect of chemical composition on the atomic structure of the films was studied by reflection high-energy electron diffraction, x-ray photoelectron spectroscopy and field emission scanning electron microscopy methods. The films were found to be amorphous, consisting only of three components: Hf-metal clusters, Hf4O7 suboxide and stoichiometric HfO2. The relative concentration of these components varies with changing x. The surface of the films contains the increased oxygen content compared to the bulk. It was found that the Hf4O7 suboxide concentration is maximal at x = 1.8. The concept of hafnium oxide film growth by the IBSD method is proposed to explain the lack of suboxides variety in the films and the instability of HfO2, when annealed at high temperature.

  15. Maltodextrin and fat preference deficits in "taste-blind" P2X2/P2X3 knockout mice.

    PubMed

    Sclafani, Anthony; Ackroff, Karen

    2014-07-01

    Adenosine triphosphate is a critical neurotransmitter in the gustatory response to the 5 primary tastes in mice. Genetic deletion of the purinergic P2X2/P2X3 receptor greatly reduces the neural and behavioral response to prototypical primary taste stimuli. In this study, we examined the behavioral response of P2X double knockout mice to maltodextrin and fat stimuli, which appear to activate additional taste channels. P2X double knockout and wild-type mice were given 24-h choice tests (vs. water) with ascending concentrations of Polycose and Intralipid. In Experiment 1, naive double knockout mice, unlike wild-type mice, were indifferent to dilute (0.5-4%) Polycose solutions but preferred concentrated (8-32%) Polycose to water. In a retest, the Polycose-experienced double knockout mice, like wild-type mice, preferred all Polycose concentrations. In Experiment 2, naive double knockout mice, unlike wild-type mice, were indifferent to dilute (0.313-2.5%) Intralipid emulsions but preferred concentrated (5-20%) Intralipid to water. In a retest, the fat-experienced double knockout mice, like wild-type mice, strongly preferred 0.313-5% Intralipid to water. These results indicate that the inherent preferences of mice for maltodextrin and fat are dependent upon adenosine triphosphate taste cell signaling. With experience, however, P2X double knockout mice develop strong preferences for the nontaste flavor qualities of maltodextrin and fat conditioned by the postoral actions of these nutrients.

  16. Digital Geologic Map of the Redding 1° x 2° Quadrangle, Shasta, Tehama, Humboldt, and Trinity Counties, California

    USGS Publications Warehouse

    Fraticelli, Luis A.; Albers, John P.; Irwin, William P.; Blake, Milton C.; Wentworth, Carl M.

    2012-01-01

    The Redding 1° x 2 quadrangle in northwestern California transects the Franciscan Complex and southern Klamath Mountains province as well as parts of the Great Valley Complex, northern Great Valley, and southernmost Cascades volcanic province. The tectonostratigraphic terranes of the Klamath province represent slices of oceanic crust, island arcs, and overlying sediment that range largely from Paleozoic to Jurassic in age. The Eastern Klamath terrane forms the nucleus to which the other terranes were added westward, primarily during Jurassic time, and that package was probably accreted to North America during earliest Cretaceous time. The younger Franciscan Complex consists of a sequence of westward younging tectonostratigraphic terranes of late Jurassic to Miocene age that were accreted to North America from mid-Cretaceous through Miocene time, with the easternmost being the most strongly metamorphosed. The marine Great Valley sequence, of late Jurassic and Cretaceous age, was deposited unconformably across the southernmost Klamath rocks, but in turn was underthrust at its western margin by Eastern belt Franciscan rocks. Pliocene and Quaternary volcanic rocks and sediment of the Cascades province extend into the southeastern part of the quadrangle, abutting the northernmost part of the great central valley of California. This map and database represent a digital rendition of Open-File Report 87-257, 1987, by L.A. Fraticelli, J.P. Albers, W.P. Irwin, and M.C. Blake, Jr., with various improvements and additions.

  17. Temperature dependent EXAFS study on transition metal dichalcogenides MoX2 (X  =  S, Se, Te)

    NASA Astrophysics Data System (ADS)

    Caramazza, S.; Marini, C.; Simonelli, L.; Dore, P.; Postorino, P.

    2016-08-01

    The local structure of molybdenum dichalcogenide MoX2 (X  =  S, Se, Te) single crystal has been studied by means of multi-edge (Mo, Se, and Te K-edges) extended x-ray absorption fine-structure spectroscopy as function of temperature. The temperature dependences of the interatomic distances Mo–X, Mo–Mo and X–X (X  =  S, Se, and Te) and of the corresponding Debye–Waller factors have been extracted over the 70–500 K temperature range. Exploiting the correlated Einstein model, we found that the Einstein frequencies of Mo–X and X–X bonds obtained by present data are in close agreement with the frequencies of the optical (Raman and infrared) stretching modes for both MoS2 and MoSe2, whereas a significant deviation has been found for MoTe2. A similar anomaly has been found for the force constants related to the Mo–X bonds in the MoTe2 case. Our findings, accordingly with the results reported in a recent theoretical paper, support the idea that the optical vibrational modes have a dominant role in MoS2 and MoSe2, whereas the effects of acoustic vibrational modes cannot be neglected in the case of MoTe2.

  18. SUDDEN PHOTOSPHERIC MOTION AND SUNSPOT ROTATION ASSOCIATED WITH THE X2.2 FLARE ON 2011 FEBRUARY 15

    SciTech Connect

    Wang, Shuo; Liu, Chang; Deng, Na; Wang, Haimin

    2014-02-20

    The Helioseismic and Magnetic Imager provides 45 s cadence intensity images and 720 s cadence vector magnetograms. These unprecedented high-cadence and high-resolution data give us a unique opportunity to study the change of photospheric flows and sunspot rotations associated with flares. By using the differential affine velocity estimator method and the Fourier local correlation tracking method separately, we calculate velocity and vorticity of photospheric flows in the flaring NOAA AR 11158, and investigate their temporal evolution around the X2.2 flare on 2011 February 15. It is found that the shear flow around the flaring magnetic polarity inversion line exhibits a sudden decrease, and both of the two main sunspots undergo a sudden change in rotational motion during the impulsive phase of the flare. These results are discussed in the context of the Lorentz-force change that was proposed by Hudson et al. and Fisher et al. This mechanism can explain the connections between the rapid and irreversible photospheric vector magnetic field change and the observed short-term motions associated with the flare. In particular, the torque provided by the horizontal Lorentz force change agrees with what is required for the measured angular acceleration.

  19. On the line profile changes observed during the X2.2 class flare in the active region NOAA 11158

    NASA Astrophysics Data System (ADS)

    Raja Bayanna, Ankala; Kumar, Brajesh; Venkatakrishnan, Parameswaran; Kunchandy Mathew, Shibu; Ravindra, Belur; Mathur, Savita; Garcia, Rafael A.

    2014-02-01

    The solar active region NOAA 11158 produced a series of flares during its passage through the solar disk. The first major flare (of class X2.2) of the current solar cycle occurred in this active region on 2011 February 15 around 01:50 UT. We have analyzed the Dopplergrams and magnetograms obtained by the Helioseismic and Magnetic Imager (HMI) instrument onboard Solar Dynamics Observatory to examine the photospheric velocity and magnetic field changes associated with this flare. The HMI instrument provides high-quality Doppler and magnetic maps of the solar disk with 0.5″ spatial scale at a cadence of 45 s along with imaging spectroscopy. We have identified five locations of velocity transients in the active region during the flare. These transient velocity signals are located in and around the flare ribbons as observed by Hinode in the Ca II H wavelength and the footpoints of hard X-ray enhancement are in the energy range 12-25 keV from RHESSI. The changes in shape and width of two circular polarization states have been observed at the time of transients in three out of five locations. Forward modeling of the line profiles shows that the change in atmospheric parameters such as magnetic field strength, Doppler velocity and source function could explain the observed changes in the line profiles with respect to the pre-flare condition.

  20. Unraveling the formation of HCPH(X2A') molecules in extraterrestrial environments: crossed molecular beam study of the reaction of carbon atoms, C(3Pj), with phosphine, PH3(X1A1).

    PubMed

    Guo, Y; Gu, X; Zhang, F; Sun, B J; Tsai, M F; Chang, A H H; Kaiser, R I

    2007-05-01

    The reaction between ground state carbon atoms, C(3P(j)), and phosphine, PH3(X(1)A1), was investigated at two collision energies of 21.1 and 42.5 kJ mol(-1) using the crossed molecular beam technique. The chemical dynamics extracted from the time-of-flight spectra and laboratory angular distributions combined with ab initio calculations propose that the reaction proceeds on the triplet surface via an addition of atomic carbon to the phosphorus atom. This leads to a triplet CPH3 complex. A successive hydrogen shift forms an HCPH2 intermediate. The latter was found to decompose through atomic hydrogen emission leading to the cis/trans-HCPH(X(2)A') reaction products. The identification of cis/trans-HCPH(X(2)A') molecules under single collision conditions presents a potential pathway to form the very first carbon-phosphorus bond in extraterrestrial environments like molecular clouds and circumstellar envelopes, and even in the postplume chemistry of the collision of comet Shoemaker-Levy 9 with Jupiter.

  1. A crossed molecular beams study of the reaction of the ethynyl radical (C2H(X2Sigma+)) with allene (H2CCCH2(X1A1)).

    PubMed

    Zhang, Fangtong; Kim, Seol; Kaiser, Ralf I

    2009-06-21

    The crossed beams reaction of ground state ethynyl radicals, C(2)H(X(2)Sigma(+)), with allene, H(2)CCCH(2)(X(1)A(1)), was conducted under single collision conditions at a collision energy of 22.0 +/- 0.4 kJ mol(-1). The center-of-mass functions were combined with earlier ab initio calculations and revealed that the reaction was barrier-less, proceeded via indirect reaction dynamics through an addition of the ethynyl radical to the terminal carbon atom of the allene molecule, and was terminated by atomic hydrogen emission via a tight exit transition state to form the ethynylallene product. The overall reaction was found to be exoergic by 93 +/- 15 kJ mol(-1). Since the reaction is barrier-less, exoergic, and all transition states involved are located below the energy level of the separated reactants, the formation of ethynylallene is predicted to take place in low temperature atmospheres of planets and their satellites such as Titan and also in cold molecular clouds via the neutral-neutral reaction of ethynyl radicals with allene. Implications to interstellar chemistry and a comparison with the chemistry of the isoelectronic cyano radical, CN(X(2)Sigma(+)), are also presented.

  2. Perturbation analysis for the rotational spectrum of the NiBr radical in the X2Pi3/2 and A2Delta5/2 states.

    PubMed

    Yamazaki, Emi; Okabayashi, Toshiaki; Tanimoto, Mitsutoshi

    2004-07-01

    The millimeter- and submillimeter-wave spectra of the NiBr radical in the X (2)Pi(3/2) and A (2)Delta(5/2) states were observed by a source-modulated microwave spectrometer. The NiBr radical was generated in a dc glow discharge through the mixture of Br(2) vapor and Ar gas by the sputtering reaction with a Ni cathode. Observed transition frequencies were independently analyzed for both electronic states using a standard polynomial expression of a Hund's case (c) approximation. Anomalous behavior of the effective molecular constants in the X (2)Pi(3/2) state was interpreted as the result of the perturbation between the X (2)Pi(3/2) and A (2)Delta(5/2) states. The deperturbed molecular constants were derived using a simplified supermultiplet Hamiltonian including the interaction terms between the two electronic states.

  3. Influence of anionic vacancies on the conductivity of La9.33Si6-xAlxO26-x/2 oxide conductors with an oxyapatite structure

    NASA Astrophysics Data System (ADS)

    Inoubli, A.; Kahlaoui, M.; Sobrados, I.; Chefi, S.; Madani, A.; Sanz, J.; Ben Haj Amara, A.

    2014-12-01

    Al-doped oxyapatite-type lanthanum silicates La9.33Si6-xAlxO26-x/2x/2 (x = 0, 0.4, 0.8 and 1) powders have been prepared by the solid state reaction at high temperature in order to determine the influence of anionic vacancies on the electrical properties of the material. The crystal structure and properties of La9.33Si6-xAlxO26-x/2x/2 powders have been studied by X-ray diffraction (XRD) patterns, magic-angle spinning nuclear magnetic resonance (MAS-NMR) technique and complex impedance analysis. All the compounds of La9.33Si6-xAlxO26-x/2x/2 oxyapatites doped with Al3+ consist of a hexagonal structure with a P63/m space group. Lanthanum silicates doped with trivalent Al3+ have a higher conductivity than those without trivalent Al3+ at the Si4+ site. The extra oxygen O(4) atoms in site 2a (0, 0, 0.25) occupy channels running through the structure that are responsible for the high oxygen ion conduction. However, Al substitution seems to produce oxygen vacancies and create another pathway for oxide ions. The expansion of the channels (La(1)-O(4) distance) leads to an increase in the conductivity. For the best sample (x = 1), the conductivity observed was 5 × 10-3 S cm-1 at 750 °C.

  4. The rare-earth metal carbide halide superconductors RE 2C 2X 2 (RE=Y, La; X=Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Kremer, R. K.; Ahn, K.; Henn, R. W.; Mattausch, Hj; Schnelle, W.; Stolovits, A.; Simon, A.

    1999-05-01

    Superconductivity in layered yttrium carbide bromides and iodides with transition temperatures ranging up to 11.6 K is achieved by adjusting the Br:I, ratio to ≈1:3 in phases of Y 2C 2(Br,I) 2. In our contribution, we compile basic physical and chemical properties of Y 2C 2X 2 (X=Cl, Br, I) and present new results of the La-based phases La 2C 2X 2 (X=Br, I).

  5. Catalytic decomposition of 4-phenoxyphenol to aromatics over Pd/Cs(x)H3.0-x PW12O40/activated carbon aerogel (X = 2.0-3.0).

    PubMed

    Park, Hai Woong; Hong, Ung Gi; Lee, Yoon Jae; Choi, Jung Ho; Song, In Kyu

    2013-12-01

    Cesium-exchanged heteropolyacid (Cs(x)H3.0-xPW12O40) was impregnated onto activated carbon aerogel (ACA) with a variation of cesium content (X = 2.0, 2.3, 2.5, 2.7, and 3.0) in order to provide acid sites to ACA. Palladium catalysts were then supported on Cs(x)H3.0-xPW12O40-impregnated activated carbon aerogel (Pd/Cs(x)H3.0-xPW12O40/ACA, X = 2.0-3.0) by an incipient wetness impregnation method for use in the decomposition of lignin model compound to aromatics. 4-Phenoxyphenol was used as a lignin model compound for representing 4-O-5 linkage of lignin. In the catalytic decomposition of 4-phenoxyphenol over Pd/Cs(X)H3.0-xPW12O40/ACA, cyclohexanol, benzene, and phenol were mainly produced. Conversion of 4-phenoxyphenol and total yield for main products (cyclohexanol, benzene, and phenol) were closely related to the acidity of Pd/Cs(x)H3.0-xPW12O40/ACA. Conversion of 4-phenoxyphenol and total yield for main products increased with increasing acidity of Pd/Cs(x)H3.0-xPW12O40/ACA. Among the catalysts tested, Pd/Cs2.5H0.5PW12O40/ACA catalyst with the largest acidity showed the highest conversion of 4-phenoxyphenol and total yield for main products. Therefore, it is concluded that acidity of catalysts would be an important factor determining the catalytic performance in the decomposition of 4-phenoxyphenol. PMID:24266173

  6. Magnetohydrodynamic simulation of the x2.2 solar flare on 2011 February 15. I. Comparison with the observations

    SciTech Connect

    Inoue, S.; Magara, T.; Choe, G. S.; Hayashi, K.; Park, Y. D.

    2014-06-20

    We performed a magnetohydrodynamic (MHD) simulation using a nonlinear force-free field (NLFFF) in solar active region 11158 to clarify the dynamics of an X2.2-class solar flare. We found that the NLFFF never shows the dramatic dynamics seen in observations, i.e., it is in a stable state against the perturbations. On the other hand, the MHD simulation shows that when the strongly twisted lines are formed at close to the neutral line, which are produced via tether-cutting reconnection in the twisted lines of the NLFFF, they consequently erupt away from the solar surface via the complicated reconnection. This result supports the argument that the strongly twisted lines formed in NLFFF via tether-cutting reconnection are responsible for breaking the force balance condition of the magnetic fields in the lower solar corona. In addition to this, the dynamical evolution of these field lines reveals that at the initial stage the spatial pattern of the footpoints caused by the reconnection of the twisted lines appropriately maps the distribution of the observed two-ribbon flares. Interestingly, after the flare, the reconnected field lines convert into a structure like the post-flare loops, which is analogous to the extreme ultraviolet image taken by the Solar Dynamics Observatory. Eventually, we found that the twisted lines exceed a critical height at which the flux tube becomes unstable to the torus instability. These results illustrate the reliability of our simulation and also provide an important relationship between flare and coronal mass ejection dynamics.

  7. Numerical Prediction of Radiation Measurements Taken in the X2 Facility for Mars and Titan Gas Mixtures

    NASA Technical Reports Server (NTRS)

    Palmer, Grant; Prabhu, Dinesh; Brandis, Aaron; McIntyre, Timothy J.

    2011-01-01

    Thermochemical relaxation behind a normal shock in Mars and Titan gas mixtures is simulated using a CFD solver, DPLR, for a hemisphere of 1 m radius; the thermochemical relaxation along the stagnation streamline is considered equivalent to the flow behind a normal shock. Flow simulations are performed for a Titan gas mixture (98% N2, 2% CH4 by volume) for shock speeds of 5.7 and 7.6 km/s and pressures ranging from 20 to 1000 Pa, and a Mars gas mixture (96% CO2, and 4% N2 by volume) for a shock speed of 8.6 km/s and freestream pressure of 13 Pa. For each case, the temperatures and number densities of chemical species obtained from the CFD flow predictions are used as an input to a line-by-line radiation code, NEQAIR. The NEQAIR code is then used to compute the spatial distribution of volumetric radiance starting from the shock front to the point where thermochemical equilibrium is nominally established. Computations of volumetric spectral radiance assume Boltzmann distributions over radiatively linked electronic states of atoms and molecules. The results of these simulations are compared against experimental data acquired in the X2 facility at the University of Queensland, Australia. The experimental measurements were taken over a spectral range of 310-450 nm where the dominant contributor to radiation is the CN violet band system. In almost all cases, the present approach of computing the spatial variation of post-shock volumetric radiance by applying NEQAIR along a stagnation line computed using a high-fidelity flow solver with good spatial resolution of the relaxation zone is shown to replicate trends in measured relaxation of radiance for both Mars and Titan gas mixtures.

  8. ConnectX-2 InfiniBand Management Queues: First Investigation of the New Support for Network Offloaded Collective Operations

    SciTech Connect

    Graham, Richard L; Poole, Stephen W; Shamis, Pavel; Bloch, Gil; Bloch, Noam; Chapman, Hillel; Kagan, Michael; Shahar, Ariel; Rabinovitz, Ishai; Shainer, Gilad

    2010-01-01

    This paper introduces the newly developed Infini-Band (IB) Management Queue capability, used by the Host Channel Adapter (HCA) to manage network task data flow dependancies, and progress the communications associated with such flows. These tasks include sends, receives, and the newly supported wait task, and are scheduled by the HCA based on a data dependency description provided by the user. This functionality is supported by the ConnectX-2 HCA, and provides the means for delegating collective communication management and progress to the HCA, also known as collective communication offload. This provides a means for overlapping collective communications managed by the HCA and computation on the Central Processing Unit (CPU), thus making it possible to reduce the impact of system noise on parallel applications using collective operations. This paper further describes how this new capability can be used to implement scalable Message Passing Interface (MPI) collective operations, describing the high level details of how this new capability is used to implement the MPI Barrier collective operation, focusing on the latency sensitive performance aspects of this new capability. This paper concludes with small scale benchmark experiments comparing implementations of the barrier collective operation, using the new network offload capabilities, with established point-to-point based implementations of these same algorithms, which manage the data flow using the central processing unit. These early results demonstrate the promise this new capability provides to improve the scalability of high performance applications using collective communications. The latency of the HCA based implementation of the barrier is similar to that of the best performing point-to-point based implementation managed by the central processing unit, starting to outperform these as the number of processes involved in the collective operation increases.

  9. TIME DELAYS IN QUASI-PERIODIC PULSATIONS OBSERVED DURING THE X2.2 SOLAR FLARE ON 2011 FEBRUARY 15

    SciTech Connect

    Dolla, L.; Marque, C.; Seaton, D. B.; Dominique, M.; Berghmans, D.; Cabanas, C.; De Groof, A.; Verdini, A.; West, M. J.; Zhukov, A. N.; Van Doorsselaere, T.; Schmutz, W.; Zender, J.

    2012-04-10

    We report observations of quasi-periodic pulsations (QPPs) during the X2.2 flare of 2011 February 15, observed simultaneously in several wavebands. We focus on fluctuations on timescale 1-30 s and find different time lags between different wavebands. During the impulsive phase, the Reuven Ramaty High Energy Solar Spectroscopic Imager channels in the range 25-100 keV lead all the other channels. They are followed by the Nobeyama RadioPolarimeters at 9 and 17 GHz and the extreme-ultraviolet (EUV) channels of the Euv SpectroPhotometer (ESP) on board the Solar Dynamic Observatory. The zirconium and aluminum filter channels of the Large Yield Radiometer on board the Project for On-Board Autonomy satellite and the soft X-ray (SXR) channel of ESP follow. The largest lags occur in observations from the Geostationary Operational Environmental Satellite, where the channel at 1-8 A leads the 0.5-4 A channel by several seconds. The time lags between the first and last channels is up to Almost-Equal-To 9 s. We identified at least two distinct time intervals during the flare impulsive phase, during which the QPPs were associated with two different sources in the Nobeyama RadioHeliograph at 17 GHz. The radio as well as the hard X-ray channels showed different lags during these two intervals. To our knowledge, this is the first time that time lags are reported between EUV and SXR fluctuations on these timescales. We discuss possible emission mechanisms and interpretations, including flare electron trapping.

  10. Spectral analysis of LMC X-2 with XMM/Newton: unveiling the emission process in the extragalactic Z-source

    NASA Astrophysics Data System (ADS)

    Lavagetto, G.; Iaria, R.; D'Aı, A.; di Salvo, T.; Robba, N. R.

    2008-01-01

    Aims:We present the results of the analysis of an archival observation of LMC X-2 performed with XMM/Newton. The spectra taken by high-precision instruments have never been analyzed before. Methods: We find an X-ray position for the source that is inconsistent with the one obtained by ROSAT, but in agreement with the Einstein position and that of the optical counterpart. The correlated spectral and timing behaviour of the source suggests that the source is probably in the normal branch of its X-ray color-color diagram. The spectrum of the source can be fitted with a blackbody with a temperature 1.5 keV plus a disc blackbody at 0.8 keV. Photoelectric absorption from neutral matter has an equivalent hydrogen column of 4 × 1020 cm-2. An emission line, which we identify as the O VIII Lyman-α line, is detected, while no feature due to iron is detected in the spectrum. Results: We argue that the emission of this source can be straightforwardly interpreted as the sum of the emission from a boundary layer between the NS and the disc and a blackbody component coming from the disc itself. Other canonical models that are used to fit Z-sources do not give a satisfactory fit to the data. The detection of the O VIII emission line (and the lack of detection of lines in the iron region) can be due to the fact that the source lies in the Large Magellanic Cloud.

  11. 1 Hz FLARING IN THE ACCRETING MILLISECOND PULSAR NGC 6440 X-2: DISK TRAPPING AND ACCRETION CYCLES

    SciTech Connect

    Patruno, Alessandro; D'Angelo, Caroline

    2013-07-10

    The dynamics of the plasma in the inner regions of an accretion disk around accreting millisecond X-ray pulsars (AMXPs) is controlled by the magnetic field of the neutron star. The interaction between an accretion disk and a strong magnetic field is not well understood, particularly at low accretion rates (the so-called propeller regime). This is due in part to the lack of clear observational diagnostics to constrain the physics of the disk-field interaction. Here, we associate the strong {approx}1 Hz modulation seen in the AMXP NGC 6440 X-2 with an instability that arises when the inner edge of the accretion disk is close to the corotation radius (where the stellar rotation rate matches the Keplerian speed in the disk). A similar modulation has previously been observed in another AMXP (SAX J1808.4-3658) and we suggest that the two phenomena are related and that this may be a common phenomenon among other magnetized systems. Detailed comparisons with theoretical models suggest that when the instability is observed, the interaction region between the disk and the field is very narrow-of the order of 1 km. Modeling further suggests that there is a transition region ({approx}1-10 km) around the corotation radius where the disk-field torque changes sign from spin-up to spin-down. This is the first time that a direct observational constraint has been placed on the width of the disk-magnetosphere interaction region, in the frame of the trapped-disk instability model.

  12. Self-organization in a simple model of adaptive agents playing 2 x 2 games with arbitrary payoff matrices.

    PubMed

    Fort, H; Viola, S

    2004-03-01

    We analyze, both analytically and numerically, the self-organization of a system of "selfish" adaptive agents playing an arbitrary iterated pairwise game (defined by a 2 x 2 payoff matrix). Examples of possible games to play are the prisoner's dilemma (PD) game, the chicken game, the hero game, etc. The agents have no memory, use strategies not based on direct reciprocity nor "tags" and are chosen at random, i.e., geographical vicinity is neglected. They can play two possible strategies: cooperate (C) or defect (D). The players measure their success by comparing their utilities with an estimate for the expected benefits and update their strategy following a simple rule. Two versions of the model are studied: (1) the deterministic version (the agents are either in definite states C or D) and (2) the stochastic version (the agents have a probability c of playing C). Using a general master equation we compute the equilibrium states into which the system self-organizes, characterized by their average probability of cooperation c(eq). Depending on the payoff matrix, we show that c(eq) can take five different values. We also consider the mixing of agents using two different payoff matrices and show that any value of c(eq) can be reached by tuning the proportions of agents using each payoff matrix. In particular, this can be used as a way to simulate the effect of a fraction d of "antisocial" individuals--incapable of realizing any value to cooperation--on the cooperative regime hold by a population of neutral or "normal" agents. PMID:15089364

  13. RESPONSE OF THE PHOTOSPHERIC MAGNETIC FIELD TO THE X2.2 FLARE ON 2011 FEBRUARY 15

    SciTech Connect

    Wang Shuo; Liu Chang; Liu Rui; Deng Na; Wang Haimin; Liu Yang

    2012-02-15

    It is well known that the long-term evolution of the photospheric magnetic field plays an important role in building up free energy to power solar eruptions. Observations, despite being controversial, have also revealed a rapid and permanent variation of the photospheric magnetic field in response to the coronal magnetic field restructuring during the eruption. The Helioseismic and Magnetic Imager instrument (HMI) on board the newly launched Solar Dynamics Observatory produces seeing-free full-disk vector magnetograms at consistently high resolution and high cadence, which finally makes possible an unambiguous and comprehensive study of this important back-reaction process. In this study, we present a near disk-center, GOES-class X2.2 flare, which occurred in NOAA AR 11158 on 2011 February 15. Using the magnetic field measurements made by HMI, we obtained the first solid evidence of a rapid (in about 30 minutes) and irreversible enhancement in the horizontal magnetic field at the flaring magnetic polarity inversion line (PIL) by a magnitude of {approx}30%. It is also shown that the photospheric field becomes more sheared and more inclined. This field evolution is unequivocally associated with the flare occurrence in this sigmoidal active region, with the enhancement area located in between the two chromospheric flare ribbons and the initial conjugate hard X-ray footpoints. These results strongly corroborate our previous conjecture that the photospheric magnetic field near the PIL must become more horizontal after eruptions, which could be related to the newly formed low-lying fields resulting from the tether-cutting reconnection.

  14. Bruker SMART X2S Benchtop System: A Means to Making X-Ray Crystallography More Mainstream in the Undergraduate Laboratory

    ERIC Educational Resources Information Center

    Guzei, Ilia A.; Hill, Nicholas J.; Zakai, Uzma I.

    2010-01-01

    Bruker SMART X2S is a portable benchtop diffractometer that requires only a 110 V outlet to operate. The instrument operation is intuitive and facile with an automation layer governing the workflow from behind the scenes. The user participation is minimal. At the end of an experiment, the instrument attempts to solve the structure automatically;…

  15. Structure and radiation effect of Er-stuffed pyrochlore Er2(Ti2-xErx)O7-x/2 (x = 0-0.667)

    NASA Astrophysics Data System (ADS)

    Yang, D. Y.; Xu, C. P.; Fu, E. G.; Wen, J.; Liu, C. G.; Zhang, K. Q.; Wang, Y. Q.; Li, Y. H.

    2015-08-01

    Er-stuffed pyrochlore series Er2(Ti2-xErx)O7-x/2 (x = 0, 0.162, 0.286, 0.424 and 0.667) were synthesized using conventional ceramic processing procedures. The structure of Er2(Ti2-xErx)O7-x/2 is effectively tailored by the Er stuffing level (x). In order to study the radiation effect of Er-stuffed pyrochlores, irradiation experiments were performed with 400 keV Ne2+ ions to fluences ranging from 5 × 1014 to 3.0 × 1015 ions/cm2 at cryogenic condition. Irradiation induced microstructural evolution was examined using a grazing incidence X-ray diffraction technique. It is found that the irradiated layer of Er2(Ti2-xErx)O7-x/2 undergoes significant lattice disordering and swelling at fluences of ⩽1.5 × 1015 ions/cm2 and amorphization at fluences of ⩾1.5 × 1015 ions/cm2. The radiation effect depends strongly on the chemical compositions of the samples. Both the lattice swelling percentage and the amorphous fraction decrease with increasing x. The experimental results are discussed in the context of cation antisite defect. The defect formation energy which varies as a function of x is responsible for the difference in the structural behaviors of Er2(Ti2-xErx)O7-x/2 under 400 keV Ne2+ ion irradiation.

  16. Sport Ability Beliefs, 2 x 2 Achievement Goals, and Intrinsic Motivation: The Moderating Role of Perceived Competence in Sport and Exercise

    ERIC Educational Resources Information Center

    Wang, C. K. John; Liu, Woon Chia; Lochbaum, Marc R.; Stevenson, Sarah J.

    2009-01-01

    We examined whether perceived competence moderated the relationships between implicit theories, 2 x 2 achievement goals, and intrinsic motivation for sports and physical activity. We placed 309 university students into high and moderate perceived competence groups. When perceived competence was high, entity beliefs did not predict the…

  17. The Conterminous United States Mineral Assessment Program; background information to accompany folio of geologic and mineral resource maps of the Silver City 1 degree x 2 degrees Quadrangle, New Mexico and Arizona

    USGS Publications Warehouse

    Richter, Donald H.; Houser, B.B.; Watts, K.C.; Klein, D.P.; Sharp, W.N.; Drewes, Harald; Hedlund, D.C.; Raines, G.L.; Hassemer, J.R.

    1987-01-01

    The Silver City 1 ? x 2 ? quadrangle, consisting of about 20,650 km2 in southwestern New Mexico and southeastern Arizona, has been investigated by a multidisciplinary research team for the purpose of assessing its mineral resource potential. The results of this investigation are in a folio of 21 maps that contain detailed information on the geology, geochemistry, geophysics, mineral deposits, and potential mineral resources of the quadrangle. This Circular provides background information on the various studies and integrates the component maps. It contains an extensive selected bibliography pertinent to the geology and mineral deposits of the quadrangle. The quadrangle has produced more than $3.5 billion in mineral products since about 1850 and contains significant resources of gold, silver, copper, molybdenum, lead, zinc, iron, manganese-iron, zeolite minerals, and possibly tin and tungsten.

  18. Fourier transform microwave spectroscopy of HZnCN(X 1Sigma+) and ZnCN(X 2Sigma+).

    PubMed

    Sun, M; Apponi, A J; Ziurys, L M

    2009-01-21

    The pure rotational spectrum of HZnCN in its X (1)Sigma(+) electronic state has been recorded using pulsed Fourier transform microwave (FTMW) techniques in the frequency range 7-39 GHz-the first spectroscopic study of this species in the gas phase. The FTMW spectrum of ZnCN(X (2)Sigma(+)) has been measured as well. A new FTMW spectrometer with an angled beam and simplified electronics, based on a cryopump, was employed for these experiments. The molecules were created in a dc discharge from a gas mixture of Zn(CH(3))(2) and cyanogen (1% D(2) for the deuterated analogs), diluted with argon, that was expanded supersonically from a pulsed nozzle. Seven isotopologues of HZnCN arising from zinc, deuterium, and (13)C substitutions were studied; for every species, between three and five rotational transitions were recorded, each consisting of numerous hyperfine components arising from nitrogen, and in certain cases, deuterium, and 67-zinc nuclear spins. Four transitions of ZnCN were measured. From these data, rotational, nuclear spin-rotation, and quadrupole coupling constants have been determined for HZnCN, as well as rotational, and magnetic and quadrupole hyperfine parameters for the ZnCN radical. The bond lengths determined for HZnCN are r(H-Zn)=1.495 A, r(Zn-C)=1.897 A, and r(C-N)=1.146 A, while those for ZnCN are r(Zn-C)=1.950 A and r(C-N)=1.142 A. The zinc-carbon bond length thus shortens with the addition of the H atom. The nitrogen quadrupole coupling constant eqQ was found to be virtually identical in both cyanide species (-5.089 and -4.931 MHz), suggesting that the electric field gradient across the N nucleus is not influenced by the H atom. The quadrupole constant for the (67)Zn nucleus in H(67)ZnCN is unusually large relative to that in (67)ZnF (-104.578 versus -60 MHz), evidence that the bonding in the cyanide has more covalent character than in the fluoride. This study additionally suggests that hydrides of other metal cyanide species are likely candidates

  19. Experimental investigation of the complete inner shell hydration energies of Ca2+: threshold collision-induced dissociation of Ca(2+)(H2O)x Complexes (x = 2-8).

    PubMed

    Carl, Damon R; Armentrout, P B

    2012-04-19

    The sequential bond energies of Ca(2+)(H(2)O)(x) complexes, where x = 1-8, are measured by threshold collision-induced dissociation (TCID) in a guided ion beam tandem mass spectrometer. From an electrospray ionization source that produces an initial distribution of Ca(2+)(H(2)O)(x) complexes where x = 6-8, complexes down to x = 2 are formed using an in-source fragmentation technique. Ca(2+)(H(2)O) cannot be formed in this source because charge separation into CaOH(+) and H(3)O(+) is a lower energy pathway than simple water loss from Ca(2+)(H(2)O)(2). The kinetic energy dependent cross sections for dissociation of Ca(2+)(H(2)O)(x) complexes, where x = 2-9, are examined over a wide energy range to monitor all dissociation products and are modeled to obtain 0 and 298 K binding energies. Analysis of both primary and secondary water molecule losses from each sized complex provides thermochemistry for the sequential hydration energies of Ca(2+) for x = 1-8 and the first experimental values for x = 1-4. Additionally, the thermodynamic onsets leading to the charge separation products from Ca(2+)(H(2)O)(2) and Ca(2+)(H(2)O)(3) are determined for the first time. Our experimental results for x = 1-6 agree well with previously calculated binding enthalpies as well as quantum chemical calculations performed here. Agreement for x = 1 is improved when the basis set on calcium includes core correlation.

  20. Reliable Predictions of the Thermochemistry of Boron-Nitrogen Hydrogen Storage Compounds: BxNxHy, x=2,3

    SciTech Connect

    Matus, Myrna H; Anderson, Kevin; Camaioni, Donald M; Autrey, Thomas; Dixon, David A

    2007-05-24

    Thermochemical data calculated using ab initio molecular orbital theory are reported for 16 BxNxHy compounds with x = 2, 3 and y ≥ 2x. Accurate gas phase heats of formation were obtained using coupled cluster with single and double excitations and perturbative triples (CCSD(T)) valence electron calculations extrapolated to the complete basis set (CBS) limit with additional corrections including core/valence, scalar relativistic, and spin-orbit corrections to predict the atomization energies and scaled harmonic frequencies to correct for zero point and thermal energies and estimate entropies. Computationally cheaper calculations were also performed using the G3MP2 and G3B3 variants of the Gaussian-3 method, as well as density functional theory (DFT) using the B3LYP functional. The G3MP2 heats of formation are too positive by up to ~6 kcal/mol as compared to CCSD(T)/CBS values. The more expensive G3B3 method predicts heats of formation that are too negative as compared to the CCSD(T)/CBS values by up to 3 to 4 kcal/mol. Density functional theory (DFT) using the B3LYP functional and 6-311+G** basis set predict isodesmic reaction energies to within a few kcal/mol compared to the CCSD(T)/CBS method so isodesmic reactions involving BN compounds and the analogous hydrocarbons can be used to estimate heats of formation. Heats of formation of cyclo-B3N3H12 and cyclo-B3N3H6 are, in kcal/mol at 298 K, -95.5 and -115.5, respectively using our best calculated CCSD(T)/CBS approach. The experimental value for cyclo-B3N3H6 appears to be ~7 kcal/mol too negative. Enthalpies, entropies and free energies are calculated for many dehydrocoupling and dehydrogenation reactions that convert BNH6 to alicyclic and cyclic oligomers and H2(g). Generally, the reactions are highly exothermic, and exorgonic as well, due to the release of 1 or more equivalents of H2(g). For cyclo-B3N3H12 and cyclo-B3N3H6, available experimental data for sublimation and vaporization lead to estimates of their

  1. Measurement of OH(X 2Πi υ = 2, 3, 4) Collisional Removal Rate Constants by Oxygen Atoms

    NASA Astrophysics Data System (ADS)

    Boulter, J. E.; Marschall, J.; Copeland, R. A.

    2002-05-01

    The fluorescence of vibrationally excited, ground electronic state hydroxyl radical (OH) in the airglow originates in the mesosphere-lower thermosphere (MLT) region of Earth's atmosphere. Spectroscopic measurements of this infrared emission are being made by the TIMED satellite to characterize the dynamics, temperature profiles, and HOy chemistry in the region 80-100 km. In the atmosphere, hydroxyl radicals in υ = 6-9 are formed in the reaction of hydrogen atoms with ozone; lower vibrational levels are populated through subsequent collisional deactivation by molecular oxygen. The lifetimes of the lower levels (υ <= 4) are significantly affected by collisions with atomic oxygen, as collisions with molecular oxygen are less efficient at relaxation than at higher levels. Given the importance of O-atom collisions in the atmosphere, we have developed an experimental approach and performed experiments on the collisional removal of OH(υ = 2, 3, 4) by atomic oxygen. In this work, the reaction of OH with atomic oxygen is studied using a two-laser method. Ozone is photolyzed in nitrogen with a pulsed excimer laser to generate O(1D), a portion of which reacts with either hydrogen to form OH(υ <= 4) or with water vapor to form OH(υ <= 3); the remainder is rapidly deactivated by collisions with N2 to produce ground state O(3P). A second, tunable dye laser pulse probes the OH population in a specific rovibrational state as a function of reaction time, using fluorescence from the A 2}Σ {+ - X 2Π { i} system. By adjusting the composition of the reactant gas mixture and by varying the photolysis laser fluence to control the ozone dissociation fraction, the dominant relaxation partner can be varied systematically from ozone and water or hydrogen to atomic oxygen. Experimentally determined rate constants for the removal of OH(υ = 2, 3, 4) by O(3P) are obtained at room temperature, with values of 6 x 10-11, 1.0 x 10-10 and 1.6 x 10-10 for υ = 2, 3 and 4, respectively, and 2-

  2. Summary mineral resource appraisal of the Richfield 1 degree x 2 degrees Quadrangle, west-central Utah

    USGS Publications Warehouse

    Steven, Thomas August; Morris, Hal T.

    1987-01-01

    The mineral resource potential of the Richfield 1? x 2? quadrangle, Utah, has been appraised using geological, geophysical, geochemical, and remote-sensing techniques. These studies have led to many publications giving basic data and interpretations; of these, a series of 18 maps at 1:250,000 and 1:500,000 scales summarizing aspects of the geology, geophysics, geochemistry, and remote sensing is designated the CUSMAP (Conterminous United States Mineral Appraisal Program) folio. This circular uses the data shown on these maps to appraise the mineral resource potential of the quadrangle. The oldest rocks exposed in the Richfield quadrangle are small patches of Early Proterozoic (1.7 billion years old) gneiss and schist on the west side of the Mineral Mountains. These rocks presumably formed the basement on which many thousands of meters of Late Proterozoic, Paleozoic, and lower Mesozoic sedimentary strata were deposited. These rocks were deformed during the Late Cretaceous Sevier orogeny when Precambrian and Paleozoic strata in the western part of the quadrangle were thrust relatively eastward across Paleozoic and Mesozoic strata in the eastern part of the quadrangle. Late Cretaceous and early Tertiary highlands above the overthrust belt were eroded and much of the debris was deposited in broad basins east of the belt. Volcanism in Oligocene and earliest Miocene time formed an east-northeast-trending belt of calcalkalic volcanoes across the southern half of the quadrangle. In early Miocene time, the composition of the volcanic rocks changed to a bimodal assemblage of mafic rocks and high-silica alkali rhyolite that has been erupted episodically ever since. Syngenetic mineral resources developed during formation of both sedimentary and volcanic rocks. These include limestone and dolomite, silica-rich sandstone, metalliferous black shale, evaporite deposits, zeolite deposits, pumice, cinders and scoria, and evaporitic or diagenetic deposits in playa environments. Most

  3. Chandra and Swift X-Ray Observations of the X-Ray Pulsar SMC X-2 During the Outburst of 2015

    NASA Astrophysics Data System (ADS)

    Li, K. L.; Hu, C.-P.; Lin, L. C. C.; Kong, Albert K. H.

    2016-09-01

    We report the Chandra/HRC-S and Swift/XRT observations for the 2015 outburst of the high-mass X-ray binary pulsar in the Small Magellanic Cloud, SMC X-2. While previous studies suggested that either an O star or a Be star in the field is the high-mass companion of SMC X-2, our Chandra/HRC-S image unambiguously confirms the O-type star as the true optical counterpart. Using the Swift/XRT observations, we extracted accurate orbital parameters of the pulsar binary through a time of arrivals analysis. In addition, there were two X-ray dips near the inferior conjunction, which are possibly caused by eclipses or an ionized high-density shadow wind near the companion’s surface. Finally, we propose that an outflow driven by the radiation pressure from day ∼10 played an important role in the X-ray/optical evolution of the outburst.

  4. Vatalanib decrease the positive interaction of VEGF receptor-2 and P2X2/3 receptor in chronic constriction injury rats.

    PubMed

    Liu, Shuangmei; Xu, Changshui; Li, Guilin; Liu, Han; Xie, Jinyan; Tu, Guihua; Peng, Haiying; Qiu, Shuyi; Liang, Shangdong

    2012-05-01

    Neuropathic pain can arise from a lesion affecting the peripheral nervous system. Selective P2X(3) and P2X(2/3) receptors' antagonists effectively reduce neuropathic pain. VEGF inhibitors are effective for pain relief. The present study investigated the effects of Vatalanib (VEGF receptor-2 (VEGFR-2) inhibitor) on the neuropathic pain to address the interaction of VEGFR-2 and P2X(2/3) receptor in dorsal root ganglia of chronic constriction injury (CCI) rats. Neuropathic pain symptoms following CCI are similar to most peripheral lesions as assessed by the Neuropathic Pain Symptom Inventory. Sprague-Dawley rats were randomly divided into sham group, CCI group and CCI rats treated with Vatalanib group. Mechanical withdrawal threshold and thermal withdrawal latency were measured. Co-expression of VEGFR-2 and P2X(2) or P2X(3) in L4-6 dorsal root ganglia (DRG) was detected by double-label immunofluorescence. The modulation effect of VEGF on P2X(2/3) receptor agonist-activated currents in freshly isolated DRG neurons of rats both of sham and CCI rats was recorded by whole-cell patch-clamp technique. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) in CCI group were lower than those in sham group (p<0.05). MWT and TWL in CCI rats treated with Vatalanib group were increased compared with those in CCI group (p<0.05). VEGFR-2 and P2X(2) or P2X(3) receptors were co-expressed in the cytoplasm and surface membranes of DRG. The co-expression of VEGFR-2 and P2X(2) or P2X(3) receptor in CCI group exhibited more intense staining than those in sham group and CCI rats treated with Vatalanib group, respectively. VEGF enhanced the amplitude of ATP and α,β-meATP -activated currents of both sham and CCI rats. Increment effects of VEGF on ATP and α,β-meATP -activated currents in CCI rats were higher than those in sham rats. Both ATP (100 μM) and α,β-meATP (10 μM)- activated currents enhanced by VEGF ( 1nM) were significantly blocked by Vatalanib (1

  5. A (4x2) reconstruction of CuInSe{sub 2} (001) studied by low-energy electron diffraction and soft x-ray photoemission spectroscopy

    SciTech Connect

    Deniozou, Th.; Esser, N.; Schulmeyer, Th.; Hunger, R.

    2006-01-30

    Clean and flat (001) surfaces of CuInSe{sub 2}/GaAs grown by molecular-beam epitaxy could be prepared by the combination of a Se capping and decapping process and subsequent Ar{sup +} ion sputtering and annealing. The formation of a (4x2) reconstruction was observed with low-energy electron diffraction. Soft x-ray photoemission spectroscopy was performed on the prepared surfaces and revealed surface core-level binding energy shifts in the Cu 2p{sub 3/2}, Se 3d, and In 4d levels which are associated with surface atoms. The structure model of a combined metal adatom-Se dimer structure is proposed to refer to the (4x2) reconstruction.

  6. Magnetic behavior of the metamagnetic compounds Co(S 1- xSe x) 2 under high pressure and high magnetic field

    NASA Astrophysics Data System (ADS)

    Goto, T.; Shindo, Y.; Ogawa, S.; Harada, T.

    1997-07-01

    The magnetization of the metamagnetic Co(Si 1- xSe x) 2 system with 0 ⩽ x ⩽ 0.2 has been measured under high pressure and high magnetic field. The magnetic phase diagram is determined in the T- x plane. The metamagnetic behavior under high pressure and high magnetic field and the magnetic phase diagram can be elucidated well with a theory of itinerant electron metamagnetism at finite temperatures.

  7. Geology and mineral resources of the Florence, Beaufort, Rocky Mount, and Norfolk 1/sup 0/ x 2/sup 0/ NTMS quadrangles. National Uranium Resource Evaluation program

    SciTech Connect

    Harris, W.B.

    1982-08-01

    This document provides geologic and mineral resources data for previously-issued Savannah River Laboratory hydrogeochemical and stream sediment reports of the Beaufort, Florence, Norfolk, and Rocky Mount 1/sup 0/ x 2/sup 0/ National Topographic Map Series quadrangles in the southeastern United States. This report is issued in draft form, without detailed technical and copy editing. This was done to make the report available to the public before the end of the National Uranium Resource Evaluation program.

  8. Formation of interstellar 2,4-pentadiynylidyne, HCCCCC(X 2Pi), via the neutral-neutral reaction of ground state carbon atom, C(3P), with diacetylene, HCCCCH(X 1Sigma(g)+).

    PubMed

    Sun, B J; Huang, C Y; Kuo, H H; Chen, K T; Sun, H L; Huang, C H; Tsai, M F; Kao, C H; Wang, Y S; Gao, L G; Kaiser, R I; Chang, A H H

    2008-06-28

    The interstellar reaction of ground-state carbon atom with the simplest polyyne, diacetylene (HCCCCH), is investigated theoretically to explore probable routes to form hydrogen-deficient carbon clusters at ultralow temperature in cold molecular clouds. The isomerization and dissociation channels for each of the three collision complexes are characterized by utilizing the unrestricted B3LYP/6-311G(d,p) level of theory and the CCSD(T)/cc-pVTZ calculations. With facilitation of RRKM and variational RRKM rate constants at collision energies of 0-10 kcalmol, the most probable paths, thus reaction mechanism, are determined. Subsequently, the corresponding rate equations are solved that the evolutions of concentrations of collision complexes, intermediates, and products versus time are obtained. As a result, the final products and yields are identified. This study predicts that three collision complexes, c1, c2, and c3, would produce a single final product, 2,4-pentadiynylidyne, HCCCCC(X (2)Pi), C(5)H (p1)+H, via the most stable intermediate, carbon chain HC(5)H (i4). Our investigation indicates the title reaction is efficient to form astronomically observed 2,4-pentadiynylidyne in cold molecular clouds, where a typical translational temperature is 10 K, via a single bimolecular gas phase reaction.

  9. Local environment in Ba{sub 2}In{sub 2-x}W{sub x}O{sub 5+3x/2} oxide ion conductors

    SciTech Connect

    Daviero-Minaud, Sylvie

    2009-02-15

    The actual oxygen environment of the tungsten dopant in the Ba{sub 2}In{sub 2-x}W{sub x}O{sub 5+3x/2} solid solution was revealed by combining X-ray absorption spectroscopy at the tungsten L{sub I} and L{sub III} edges and at the indium L{sub I} edge. Whatever the substitution ratio, the tungsten atoms exhibit a regular octahedral environment. When the substitution ratio increases, the oxygen vacancies are progressively filled until their total occupancy for x=2/3. For x{>=}0.3, the perovskite structure is stabilised; the tungsten atoms are randomly distributed in the structure. Although X-ray diffraction revealed a cubic symmetry for these compositions, a local distortion of the indium environment is observed when a tungsten atom is in its surrounding. - Evolution of the XANES signal of Ba{sub 2}In{sub 2-x}W{sub x}O{sub 5+x} type compounds with x=0.1 (orthorhombic), x=2/3 (cubic) and of BaWO{sub 4}, Bi{sub 2}WO{sub 6} and WO{sub 3} references, in which tungsten has, respectively, a tetrahedral, distorted octahedral and quasi-regular octahedral environment.Text3.

  10. Vibronic Coupling of tilde{B}^2A' Electronic State with the tilde{X}^2A', tilde{A}^2 a" Twofold of Isopropoxy Radical.

    NASA Astrophysics Data System (ADS)

    Roudjane, Mourad; Chhantyal-Pun, Rabi; Melnik, Dmitry G.; Miller, Terry A.; Liu, Jinjun

    2014-06-01

    We performed rotational analyses of previously reported tilde{B}^2A' ← tilde{X}^2A' and tilde{B}^2A' ← tilde{A}^2A" electronic transitions of isopropoxy radical. It is noted that certain vibronic bands belonging to both tilde{B}^2A' ← tilde{X}^2A' and tilde{B}^2A' ← tilde{A}^2A" electronic transitions exhibit unusual rotational contours inconsistent with the electronic symmetry designation of the connecting levels, and the orientation of the electronic transition dipole moment with respect to the principal axis system of the molecule is inconsistent with expectations from the molecule's electronic structure. A coupled, three-electronic-state, vibronic Hamiltonian has been used to account for vibronic interactions between the tilde{B} electronic state and the tilde{X}/ tilde{A} states, whereas an effective rotational Hamiltonian developed earlier has been used to describe the rovibronic eigenstates within the tilde{X}^2A' and tilde{A}^2 A" twofold. We show that inclusion of the vibronic coupling of the ground twofold to the upper electronic tilde{B} state is necessary to account for the observed rotational structure anomalies and present molecular parameters resulting from the rotational analysis of the vibronic spectra. R. Chhantyal-Pun and T. A. Miller, TD03, 68^th Molecular Spectroscopy Symposium, Columbus, 2013 J. Liu, D. Melnik and T. A. Miller, J. Chem. Phys., 139, 094308, (2013)

  11. Coordination Chemistry of Diiodine and Implications for the Oxidation Capacity of the Synergistic Ag(+) /X2 (X=Cl, Br, I) System.

    PubMed

    Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

    2016-08-01

    The synergistic Ag(+) /X2 system (X=Cl, Br, I) is a very strong, but ill-defined oxidant-more powerful than X2 or Ag(+) alone. Intermediates for its action may include [Agm (X2 )n ](m+) complexes. Here, we report on an unexpectedly variable coordination chemistry of diiodine towards this direction: (A)Ag-I2 -Ag(A), [Ag2 (I2 )4 ](2+) (A(-) )2 and [Ag2 (I2 )6 ](2+) (A(-) )2 ⋅(I2 )x≈0.65 form by reaction of Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) with diiodine (single crystal/powder XRD, Raman spectra and quantum-mechanical calculations). The molecular (A)Ag-I2 -Ag(A) is ideally set up to act as a 2 e(-) oxidant with stoichiometric formation of 2 AgI and 2 A(-) . Preliminary reactivity tests proved this (A)Ag-I2 -Ag(A) starting material to oxidize n-C5 H12 , C3 H8 , CH2 Cl2 , P4 or S8 at room temperature. A rough estimate of its electron affinity places it amongst very strong oxidizers like MF6 (M=4d metals). This suggests that (A)Ag-I2 -Ag(A) will serve as an easily in bulk accessible, well-defined, and very potent oxidant with multiple applications. PMID:27411163

  12. Low temperature rate constants for the N(4S) + CH(X2Πr) reaction. Implications for N2 formation cycles in dense interstellar clouds.

    PubMed

    Daranlot, Julien; Hu, Xixi; Xie, Changjian; Loison, Jean-Christophe; Caubet, Philippe; Costes, Michel; Wakelam, Valentine; Xie, Daiqian; Guo, Hua; Hickson, Kevin M

    2013-09-01

    Rate constants for the potentially important interstellar N((4)S) + CH(X(2)Πr) reaction have been measured in a continuous supersonic flow reactor over the range 56 K ≤T≤ 296 K using the relative rate technique employing both the N((4)S) + OH(X(2)Πi) and N((4)S) + CN(X(2)Σ(+)) reactions as references. Excess concentrations of atomic nitrogen were produced by the microwave discharge method upstream of the Laval nozzle and CH and OH radicals were created by the in situ pulsed laser photolysis of suitable precursor molecules. In parallel, quantum dynamics calculations of the title reaction have been performed based on accurate global potential energy surfaces for the 1(3)A' and 1(3)A'' states of HCN and HNC, brought about through a hierarchical construction scheme. Both adiabatic potential energy surfaces are barrierless, each one having two deep potential wells suggesting that this reaction is dominated by a complex-forming mechanism. The experimental and theoretical work are in excellent agreement, predicting a positive temperature dependence of the rate constant, in contrast to earlier experimental work at low temperature. The effects of the new low temperature rate constants on interstellar N2 formation are tested using a dense cloud model, yielding N2 abundances 10-20% lower than previously predicted.

  13. The ultraluminous X-ray sources NGC 1313 X-1 and X-2: A broadband study with NuSTAR and XMM-Newton

    SciTech Connect

    Bachetti, Matteo; Barret, Didier; Webb, Natalie A.; Rana, Vikram; Walton, Dominic J.; Harrison, Fiona A.; Fürst, Felix; Grefenstette, Brian W.; Madsen, Kristin K.; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Fabian, Andrew C.; Hailey, Charles J.; Hornschemeier, Ann; Ptak, Andrew F.; Zhang, William W.; Miller, Jon M.; Stern, Daniel

    2013-12-01

    We present the results of NuSTAR and XMM-Newton observations of the two ultraluminous X-ray sources: NGC 1313 X-1 and X-2. The combined spectral bandpass of the two satellites enables us to produce the first spectrum of X-1 between 0.3 and 30 keV, while X-2 is not significantly detected by NuSTAR above 10 keV. The NuSTAR data demonstrate that X-1 has a clear cutoff above 10 keV, whose presence was only marginally detectable with previous X-ray observations. This cutoff rules out the interpretation of X-1 as a black hole in a standard low/hard state, and it is deeper than predicted for the downturn of a broadened iron line in a reflection-dominated regime. The cutoff differs from the prediction of a single-temperature Comptonization model. Further, a cold disk-like blackbody component at ∼0.3 keV is required by the data, confirming previous measurements by XMM-Newton only. We observe a spectral transition in X-2, from a state with high luminosity and strong variability to a lower-luminosity state with no detectable variability, and we link this behavior to a transition from a super-Eddington to a sub-Eddington regime.

  14. Visible absorption spectroscopy of the B 2A1-X 2B2 transition of fluoroformyloxyl radical, FC(O)O

    NASA Astrophysics Data System (ADS)

    Maricq, M. Matti; Szente, Joseph J.; Li, Z.; Francisco, Joseph S.

    1993-01-01

    We report the visible absorption spectrum of the fluoroformyloxyl radical. The spectrum is assigned to the B 2A1-X 2B2 transition in FC(O)O. The origin of the excitation spectrum is observed at 13 150 cm-1 (760 nm). Extensive progressions in the OCO bending mode of the B state, ν'3 = 610 cm-1, dominate the spectrum. Three other progressions are observed: the OCO wag mode, ν'6 = 840 cm-1; the CF stretching mode, ν'2 = 1110 cm-1; and the asymmetric CO stretching mode, ν'4 = 2820 cm-1. Two series of hot bands also appear in the spectrum. From these bands the frequency of the OCO bending mode, ν`3 = 520 cm-1, is assigned for ground state FC(O)O. The experimental spectrum is compared to the results of ab initio MO calculations. These include second-order Møller-Plesset perturbation theory (UMP2) and quadratic configuration interactions theory with single and double excitations (QCISD) for both the X 2B2 and B 2A1 states. The origin of the B 2A1-X 2B2 transition and the predicted vibrational frequencies are found to be in reasonable agreement with experiment.

  15. On the origin of the differences in structure directing properties of polar metal oxyfluoride [MO(x)F(6-x)]2- (x = 1, 2) building units.

    PubMed

    Gautier, Romain; Gautier, Régis; Chang, Kelvin B; Poeppelmeier, Kenneth R

    2015-02-16

    In oxyfluoride chemistry, the [MO(x)F(6-x)](2-) anions (M = transition metal) are interesting polar building units that may be used to design polar materials, but their polar vs antipolar orientations in the solid state, which directly depend on the interactions between O(2-)/F(-) ligands and the extended structure, remain difficult to control. To improve this control, these interactions were assessed through crystallization of five related [MO(x)F(6-x)](2-) (M = Ti(4+), V(5+), Mo(6+), W(6+)) anions with organic molecules. The hybrid organic-inorganic compounds, (4,4'-bpyH2)TiF6 (1), (enH2)MoO2F4 (2), (4-hpyH)2MoO2F4·H2O (3), (4,4'-bpyH2)WO2F4 (4), and (4,4'-bpyH2)VOF5 (5), exhibit isolated [MO(x)F(6-x)](2-) anions in a hydrogen bond network. The analysis of these crystal structures in combination with DFT calculations elucidate how differences in structure directing properties of these anions arise when π-overlap between O 2p orbitals and M d orbitals is weak and significantly affected by an increase of the energy of the d orbitals from 3d to 5d.

  16. Determination of the number densities of CH(X2Π) and CH(A2Δ) radicals in a DC cascaded arc discharge plasma

    NASA Astrophysics Data System (ADS)

    Wu, Xingwei; Li, Cong; Wang, Yong; Wang, Zhiwei; Feng, Chunlei; Ding, Hongbin

    2015-09-01

    A combination of optical emission spectroscopy (OES) and cavity ring-down spectroscopy (CRDS) has enabled to determinate the number densities of CH(A2Δ) and CH(X2Π) radicals simultaneously in a cascaded arc plasma reactor operating with a CH4/Ar mixture. It is found that the number density of CH(A2Δ) radical increases with discharge current at first and then decreases. However, the number density of CH(X2Π) radical decreases with discharge current when the rate of CH4 flow to total flow is lower than 1 %, while it increases slightly with discharge current when the rate is 1.5 %. The results reveal that CH radicals are deviation from excitation equilibrium. Although OES is the simplest and most straightforward means to investigate the CH radical behavior, it is not enough to provide the information of the CH(X2Π) number density, and additional methods, such as CRDS, are needed in the cascaded arc plasma jet.

  17. Evaluation of skin surface hydration state and barrier function of stratum corneum of dorsa of hands and heels treated with PROTECT X2 skin protective cream.

    PubMed

    Kubota, Takahiro

    2012-06-01

    Skin roughness is a term commonly used in Japan to describe a poor skin condition related to a rough and dry skin surface that develops as a result of various damaging effects from the environment or skin inflammation. Recovery from skin roughness requires skin care for a long period, thus it is important to prevent development of such skin changes. PROTECT X2 contains agents used for a protective covering of the skin from frequent hand washing or use of alcohol-based disinfectants. These unique components are also thought to be effective to treat skin roughness of the dorsa of the hands and heels. In the present study, we evaluated the effectiveness of PROTECT X2 to increase skin surface hydration state, as well as enhance the barrier function of the stratum corneum of the dorsa of the hands and heels in elderly individuals. A total of 8 elderly subjects and their caretakers without any skin diseases participated in the study. They applied PROTECT X2 by themselves to the dorsum area of 1 hand and heel 3 to 5 times daily for 1 month, while the opposite sides were left untreated. We measured stratum corneum (SC) hydration and transepidermal water loss (TEWL) before beginning treatment, then 1 week and 1 month after the start of treatment to compare between the treated and untreated skin. SC hydration state after applications of PROTECT X2 was 1.5- to 3.0-fold higher than that of the untreated skin in the dorsa of both hands and heels, indicating that the moisturizing ingredients accompanied by water were replenished in those areas where the cream was applied. Also, TEWL in the dorsum of the hands was 17.0-27.9% lower on the treated side, indicating improvement in SC barrier function. On the basis of these findings, we concluded that PROTECT X2 enhances water-holding in the SC and aids the barrier function of the skin in the dorsum of the hands. In addition, we consider that this formulation is useful for not only protecting the hands from the effects of such agents

  18. Growth and optoelectronic characteristic of n-Si/p-CuIn(S 1-xSe x) 2 thin-film solar cell by solution growth technique

    NASA Astrophysics Data System (ADS)

    Chavhan, S.; Sharma, R.

    2006-07-01

    The p-CuIn(S 1-xSe x) 2 (CISS) thin films have been grown on n-Si substrate by solution growth technique. The deposition parameters, such as pH (10.5), deposition time (60 min), deposition temperature (50 °C), and concentration of bath solution (0.1 M) were optimized. Elemental analysis of the p-CuIn(S 1-xSe x) 2 thin film was confirmed by energy-dispersive analysis of X-ray (EDAX). The SEM study of absorber layer shows the uniform morphology of film as well as the continuous smooth deposition onto the n-Si substrates, whose grain size is 130 nm. CuIn(S 1-xSe x) 2 ( x=0.5) reveals (1 1 2) orientation peak and exhibits the chalcopyrite structure with lattice constant a=5.28 Å and c=11.45 Å. The J- V characteristics were measured in dark and light. The device parameters have been calculated for solar cell fabrication, V=411.09 mV, and J=14.55 mA. FF=46.55% and η=4.64% under an illumination of 60 mW/cm 2. The J- V characteristics of the device under dark condition were also studied and the ideality factor was calculated, which is equal to 2.2 for n-Si/p-CuIn(S 0.5Se 0.5) 2 heterojunction thin film.

  19. Initial steps in XY chromosome differentiation in Hoplias malabaricus and the origin of an X(1)X(2)Y sex chromosome system in this fish group.

    PubMed

    Cioffi, M B; Bertollo, L A C

    2010-12-01

    The neotropical fish, Hoplias malabaricus, is well known for its population-specific karyotypic diversity and the variation of its sex chromosomes. Seven karyomorphs (A to G) have been previously described with an XY, X(1)X(2)Y and XY(1)Y(2) sex chromosome system found in karyomorphs B, D and G, respectively. We compared the chromosomal characteristics of karyomorphs C and D using C-banding, staining with CMA(3) and DAPI, and by mapping the location of 18S rDNA, 5SHindIII-DNA and (TTAGGG)(n) repeat sequences. Our results show conserved karyotypes in both karyomorphs, a nascent XX/XY sex chromosome system in karyomorph C and the origin of neo-Y chromosome in karyomorph D. The X and Y chromosomes of karyomorph C differ only slightly because of the amplification of repetitive sequences on the X chromosome, resulting in a homomorphic condition in all females and a heteromorphic condition in all males examined. Our study showed that chromosomes X and 20 of karyomorph C have similar patterns to the X(1) and X(2) chromosomes of karyomorph D, and are probably homologous. We showed that the neo-Y chromosome of karyomorph D shares similar patterns to the chromosomes Y and 20 of karyomorph C, and probably evolved through tandem fusion between Ypter/20pter. An interstitial site of the satellite 5SHindIII-DNA on the neo-Y reinforces the hypothesized dicentric nature of this chromosome. Our study shows the initial steps in XY chromosome differentiation in H. malabaricus and, in a broader context, contributes to the understanding of the evolutionary pathway leading to a multiple X(1)X(2)Y sex chromosome system in fishes.

  20. From stable divalent to valence-fluctuating behaviour in Eu(Rh(1-x)Ir(x))2Si2 single crystals.

    PubMed

    Seiro, Silvia; Geibel, Christoph

    2011-09-21

    We have succeeded in growing high-quality single crystals of the valence-fluctuating system EuIr(2)Si(2), the divalent Eu system EuRh(2)Si(2) and the substitutional alloy Eu(Rh(1-x)Ir(x))(2)Si(2) across the range 0 < x < 1, which we characterized by means of x-ray diffraction, energy-dispersive x-ray spectroscopy, specific heat, magnetization and resistivity measurements. On increasing x, the divalent Eu ground state subsists up to x = 0.25 with a slight increase in Néel temperature, while for 0.3≤x < 0.7 a sharp hysteretic change in susceptibility and resistivity marks the first-order valence transition. For x≳0.7 the broad feature observed in the physical properties is characteristic of the continuous valence evolution beyond the critical end point of the valence transition line, and the resistivity is reminiscent of Kondo-like behaviour while the Sommerfeld coefficient indicates a mass renormalization of at least a factor of 8. The resulting phase diagram is similar to those reported for polycrystalline Eu(Pd(1-x)Au(x))(2)Si(2) and EuNi(2)(Si(1-x)Ge(x))(2), confirming its generic character for Eu systems, and markedly different to those of homologue Ce and Yb systems, which present a continuous suppression of the antiferromagnetism accompanied by a very smooth evolution of the valence. We discuss these differences and suggest them to be related to the large polarization energy of the Eu half-filled 4f shell. We further argue that the changes in the rare earth valence between RRh(2)Si(2) and RIr(2)Si(2) (R = Ce, Eu, Yb) are governed by a purely electronic effect and not by a volume effect.

  1. Clusters containing open-shell molecules. II. Equilibrium structures of ArnOH Van der Waals clusters (X2Pi, n=1 to 15)

    NASA Astrophysics Data System (ADS)

    Xu, Minzhong; Bacic, Zlatko; Hutson, Jeremy M.

    2002-09-01

    The equilibrium and low-lying isomeric structures of ArnOH (X2)Pi clusters for n=1 to 15 are investigated by simulated annealing calculations. Potential energy surfaces are obtained by a pairwise-additive approach, taking into account the open-shell nature of OH X2Pi and including spin-orbit coupling. It is found that the spin-orbit coupling suppresses the Jahn-Teller effect, and many of the clusters have high-symmetry structures (Cnnu with n>2) which would be forbidden in the absence of spin-orbit coupling. The structures are generally similar to those previously found for the closed-shell systems ArnHF and ArnHCl, but different from those for the open-shell systems ArnNO and ArnCH. This is because Ar-OH (X2)Pi, like Ar-HF and Ar-HCl but unlike Ar-NO and Ar-CH, has a near-linear equilibrium structure. ArnOH clusters for n up to 6 have all Ar atoms in a single shell around OH. In the clusters with n=7 to 9, OH is under a pentagonal pyramid formed by six Ar atoms, while the others bind to its exterior, away from OH. For n=10 to 12, the minimum-energy structures have OH inside an Arn cage, which is essentially icosahedral for n=12 but has vacancies for n=10 and 11. For n>12, the extra Ar atoms begin to form a second solvation shell. The global minimum of ArnOH may be constructed from the minimum-energy structure of Arn+1 by replacing one Ar atom with OH.

  2. A rare example of a krypton difluoride coordination compound: [BrOF2][AsF6] x 2 KrF2.

    PubMed

    Brock, David S; de Pury, Jonathan J Casalis; Mercier, Hélène P A; Schrobilgen, Gary J; Silvi, Bernard

    2010-03-17

    The synthesis of [BrOF(2)][AsF(6)] x 2 KrF(2), its structural characterization, and bonding are described in this study. Although several KrF(2) adducts with transition metal centers have been previously reported, none have been crystallographically characterized. The solid-state Raman spectrum of [BrOF(2)][AsF(6)] x 2 KrF(2) has been assigned with the aid of quantum-chemical calculations. The low-temperature (-173 degrees C) X-ray crystal structure of [BrOF(2)][AsF(6)] x 2 KrF(2) consists of isolated molecular units and represents an example of KrF(2) coordinated to a main-group atom. The coordination geometry around the BrOF(2)(+) cation renders the free valence electron lone pair more compact than in free BrOF(2)(+). The KrF(2) ligands are coordinated trans to the fluorine atoms of BrOF(2)(+) with the AsF(6)(-) anion coordinated trans to oxygen. The quantum theory of atoms in molecules (QTAIM) and electron localization function (ELF) analyses have been carried out in order to define the nature of the bonding in the complex. A significant amount of charge (0.25 e) is transferred to BrOF(2)(+) from the two KrF(2) ligands (0.10 e each) and from the AsF(6)(-) anion (0.05 e). Significant polarization also occurs within the KrF(2) ligands, which enhances the anionic characters of the fluorine bridges. The interaction energy is mostly governed by the electrostatic interaction of the positively charged bromine atom with the surrounding fluorine atoms. PMID:20170204

  3. Probing the Superconducting Order Parameter of Ba(Fe 1-x Co x)2 As 2 by Josephson Interferometry

    NASA Astrophysics Data System (ADS)

    Atkinson, J. M.; van Harlingen, D. J.; Canfield, P.; Ni, N.; Strand, J. D.

    2011-03-01

    Since the discovery of the first Fe-based superconductors in 2006, extensive effort has been directed toward characterizing and modeling the novel properties of these exotic materials, in particular, the symmetry of their superconducting order parameter. We probe the order parameter in Co-doped BaFe 2 As 2 single crystals by fabricating Josephson junctions on polished faces orthogonal to the c-axis. It has been proposed that the Fe-pnictides form electron and hole pockets in the Fermi surface that have s-wave Cooper pair symmetry but opposite phases, the so-called s +/- model. The modulation of the critical current IC as a function of magnetic flux applied along the c-axis is different for junctions fabricated on a corner (between [100] and [110] faces) or on an edge (either [100] or [110]). In the same way, the product IC R should be different for each type of junction. The combination of these effects may help us map the phase anisotropy and test for this pairing symmetry. We will present preliminary results of these studies and attempts to match them with existing theoretical models. Work supported by the Department of Energy grant BNL-150252 through the CES-EFRC.

  4. Perturbation Analysis of the (0,0) Band of the A2Π3/2 - X2Σ+ Transition in ZrN

    NASA Astrophysics Data System (ADS)

    Womack, Kaitlin A.; Dahms, Taylor; O'Brien, Leah C.; O'Brien, James J.

    2014-06-01

    The (0,0) band of the A2Π3/2 - X2Σ+ transition of ZrN is known to be perturbed. Both homogeneous and heterogeneous perturbations are observed in the spectrum. A recent high-level ab initio calculation has helped to identify several possible perturbing states. PGOPHER is used to analyze the interactions. ZrN was produced in a hollow cathode sputter source, and the spectrum was recorded in emission by a high resolution FT spectrometer. Results of the analysis will be presented.

  5. The rotational spectrum of the NiI radical in the X 2Delta(5/2) and A 2Pi(3/2) states.

    PubMed

    Miyazawa, Toru; Okabayashi, Emi Y; Koto, Fumi; Tanimoto, Mitsutoshi; Okabayashi, Toshiaki

    2006-06-14

    The millimeter- and submillimeter-wave spectra of the NiI radical in the X (2)Delta(5/2) and A (2)Pi(3/2) states were observed by a source-modulated microwave spectrometer. The NiI radical was generated by a dc glow discharge in the mixture of CH(3)I vapor and Ar gas through the sputtering reaction with a Ni cathode. Observed transition frequencies for each electronic state were independently analyzed using a polynomial energy expression based on Hund's case (c) approximation. The deperturbed rotational constants were also estimated by the perturbation analysis including interaction terms between the ground state and the lowest excited state.

  6. Einstein coefficients for rotational lines of the (0,0) band of the NO A2sigma(+)-X2Pi system

    NASA Technical Reports Server (NTRS)

    Reisel, John R.; Carter, Campbell D.; Laurendeau, Normand M.

    1992-01-01

    A summary of the spectroscopic equations necessary for prediction of the molecular transition energies and the Einstein A and B coefficients for rovibronic lines of the gamma(0,0) band of nitric oxide (NO) is presented. The calculated molecular transition energies are all within 0.57/cm of published experimental values; in addition, over 95 percent of the calculated energies give agreement with measured results within 0.25/cm. Einstein coefficients are calculated from the band A00 value and the known Hoenl-London factors and are tabulated for individual rovibronic transitions in the NO A2sigma(+)-X2Pi(0,0) band.

  7. A 2x2 W-Band Reference Time-Shifted Phase-Locked Transmitter Array in 65nm CMOS Technology

    NASA Technical Reports Server (NTRS)

    Tang, Adrian; Virbila, Gabriel; Hsiao, Frank; Wu, Hao; Murphy, David; Mehdi, Imran; Siegel, P. H.; Chang, M-C. Frank

    2013-01-01

    This paper presents a complete 2x2 phased array transmitter system operating at W-band (90-95 GHz) which employs a PLL reference time-shifting approach instead of using traditional mm-wave phase shifters. PLL reference shifting enables a phased array to be distributed over multiple chips without the need for coherent mm-wave signal distribution between chips. The proposed phased array transmitter system consumes 248 mW per array element when implemented in a 65 nm CMOS technology.

  8. Preparation and Photoluminescence Properties of Eu2+-Doped Oxyapatite-Type SrxLa10-x (SiO4)6O3-x/2

    NASA Astrophysics Data System (ADS)

    Cui, Zhao-Feng; Yuan, Shuang-Long; Yang, Yun-Xia; François, Chevire; Franck, Tessier; Chen, Guo-Rong

    2011-01-01

    Eu2+-doped oxyapatite SrxLa10-x(SiO4)6O3-x/2 phosphors are prepared by solid-state reaction at high temperatures under reducing atmosphere. Their crystal structures and photoluminescence are investigated by x-ray diffraction (XRD) and fluorescence spectroscopy, respectively. The XRD results indicate that the samples are pure oxyapatite phase (P63/m space group). The fluorescence spectra show two peaks corresponding to two sites (4f and 6h sites) for Eu2+ in the host lattice. As the Eu2+ content influences the intensity ratio of the two observed emission peaks, the photoluminescence mechanism is discussed.

  9. Photoinduced conversion of carbon dioxide and water molecules to methanol on the surface of molybdenum oxide MoO x ( x < 2)

    NASA Astrophysics Data System (ADS)

    Silaev, I. V.; Khubezhov, S. A.; Ramonova, A. G.; Grigorkina, G. S.; Kaloeva, A. G.; Demeev, Z. S.; Bliev, A. P.; Sekiba, D.; Ogura, S.; Fukutani, K.; Magkoev, T. T.

    2016-03-01

    X-ray and UV photoelectron spectroscopic data are used to demonstrate that, when pulsed laser light with a photon energy of 6.4 eV acts on the surface of nonstoichiometric molybdenum oxide MoO x ( x < 2), methanol is effectively formed from adsorbed molecules of carbon dioxide and water. The processes in which CO2 and H2O molecules are adsorbed on substrate surface defects and their bonds are activated, enhanced under the effect of photons, should be regarded as the key factors.

  10. A 2x2 multi-chip reconfigurable MOEMS mask: a stepping stone to large format microshutter arrays for coded aperture applications

    NASA Astrophysics Data System (ADS)

    McNie, Mark E.; Brown, Alan G.; King, David O.; Smith, Gilbert W.; Gordon, Neil T.; Riches, Stephen; Rogers, Stanley

    2010-08-01

    Coded aperture imaging has been used for astronomical applications for several years. Typical implementations used a fixed mask pattern and are designed to operate in the X-Ray or gamma ray bands. Recently applications have emerged in the visible and infra red bands for low cost lens-less imaging systems and system studies have shown that considerable advantages in image resolution may accrue from the use of multiple different images of the same scene - requiring a reconfigurable mask. Previously reported work focused on realising a 2x2cm single chip mask in the mid-IR based on polysilicon micro-optoelectro- mechanical systems (MOEMS) technology and its integration with ASIC drive electronics using conventional wire bonding. It employs interference effects to modulate incident light - achieved by tuning a large array of asymmetric Fabry-Perot optical cavities via an applied voltage and uses a hysteretic row/column scheme for addressing. In this paper we report on the latest results in the mid-IR for the single chip reconfigurable MOEMS mask, trials in scaling up to a mask based on a 2x2 multi-chip array and report on progress towards realising a large format mask comprising 44 MOEMS chips. We also explore the potential of such large, transmissive IR spatial light modulator arrays for other applications and in the current and alternative architectures.

  11. A 2A2<--X 2B1 absorption and Raman spectra of the OClO molecule: A three-dimensional time-dependent wave packet study

    NASA Astrophysics Data System (ADS)

    Sun, Zhigang; Lou, Nanquan; Nyman, Gunnar

    2005-02-01

    Time-dependent wave packet calculations of the (A 2A2←X 2B1) absorption and Raman spectra of the OClO molecule are reported. The Fourier grid Hamiltonian method in three dimensions is employed. The X 2B1 ground state ab initio potential energy surface reported by Peterson [J. Chem. Phys. 109, 8864 (1998)] is used together with his corresponding A 2A2 state surface or the revised surface of the A 2A2 state by Xie and Guo [Chem. Phys. Lett. 307, 109 (1999)]. Radau coordinates are used to describe the vibrations of a nonrotating OClO molecule. The split-operator method combined with fast Fourier transform is applied to propagate the wave function. We find that the ab initio A 2A2 potential energy surface better reproduces the detailed structures of the absorption spectrum at long wavelength, while the revised surface of the A 2A2 state, consistent with the work of Xie and Guo, better reproduces the overall shape and the energies of the vibrational levels. Both surfaces of the A 2A2 state can reasonably reproduce the experimental Raman spectra but neither does so in detail for the numerical model employed in the present work.

  12. Suppression of phase transitions at low temperature by chromium substitution in vanadium spinel Fe(V1-x Cr x )2O4.

    PubMed

    Kawaguchi, S; Ishibashi, H; Nagami, K; Kubota, Y

    2016-07-27

    Synchrotron powder diffraction, magnetization, and specific heat measurements have been used to investigate the structural and magnetic phase transitions in the spinel-type vanadate Fe(V1-x Cr x )2O4 (0.0  ⩽  x  ⩽  1.0). We observed five different transitions in our polycrystalline samples. The canted-type ferrimagnetic phase transition accompanied by the lattice distortion was suppressed by Cr substitution (x  =  0.2). Additionally, high-resolution synchrotron powder diffraction revealed that the low-temperature orthorhombic phase appears in FeV2O4 below 30 K and disappears by subtle Cr doping. In contrast, for x  ⩾  0.7, we observed a different magnetic transition of possibly conical-type ferrimagnetic ordering that did not induce significant lattice distortion at the transition temperature. We performed structural refinements for low-temperature phases and suggest that the crystal system of Fe(V1-x Cr x )2O4 at 15K is an orthorhombic lattice for all x values. In the orthorhombic phase, a unique behaviour was observed, with the lattice constants a and b approaching each other as Cr doping increased. This behaviour can be explained by the change of orbitally ordered states of the Fe(2+) ions. PMID:27250516

  13. Computer-aided design of AD 2 X 2 intermetallics with a ThCr2Si2-type of crystal structure

    NASA Astrophysics Data System (ADS)

    Kiselyova, N. N.; Sen'ko, O. V.; Kropotov, D. A.; Dokukin, A. A.

    2012-07-01

    Several hundred new AD 2 X 2 ( A and D are various elements; X = B, Al, Si, P, Ga, Ge, As, Sn, Sb) compounds are computer designed, and the types of their crystal structures under normal conditions are predicted. A special software package is used for the calculations; it includes a set of databases on the properties of inorganic substances and materials and a system for an analysis of these data, which is based on precedent pattern recognition methods. Only data on the properties of the elements entering into the compound compositions are used to predict unknown compounds. The parameters of elements in positions A and D (i.e., the Mendeleev-Pettifor numbers, the pseudopotential radii, and their algebraic functions) are found to mainly determine the possibility of formation of AD 2 X 2 compounds and the type of their crystal structures. New compounds of AD 2B2, AD 2Ga2, and AD 2Sn2 compositions are predicted for the first time.

  14. Substitution effects on nonlinear optical activity of (X-methylphenyl)-5-nitro-6-amino-3-pyridinecarboxmide (X=2,3,4,5,6): A DFT approach

    NASA Astrophysics Data System (ADS)

    Premkumar, S.; Asath, R. Mohamed; Rekha, T. N.; Jawahar, A.; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-01

    The substitution effects on the first order hyperpolarizability value of (X-methylphenyl)-5-nitro-6-amino-3-pyridinecarboxmide (X-MPNAPC),{X=2,3,4,5,6}molecule was calculated with the aid of density functional theory calculations. The optimized molecular structure of urea and (X-methylphenyl)-5-nitro-6-amino-3-pyridinecarboxmide (X-MPNAPC), {X=2,3,4,5,6} were predicted by the DFT/B3LYP method with cc-pVTZ basis set. The higher first order hyperpolarizability values were obtained for all molecules compared with the urea, which confirm that the higher nonlinear optical activity of the molecules. The frontier molecular orbitals (FMOs) analysis was carried out and their related molecular properties were calculated. The higher first order hyperpolarizability value was obtained for 4-MPNAPC molecule compared with other molecules, which indicates that the lower energy gap and extended π-conjugated bridge between the donor and acceptor group leads to the higher NLO activity of the molecule. Hence, this present investigation paves the way for designing the new organic NLO materials.

  15. Roles of Mas-related G protein-coupled receptor X2 on mast cell-mediated host defense, pseudoallergic drug reactions, and chronic inflammatory diseases.

    PubMed

    Subramanian, Hariharan; Gupta, Kshitij; Ali, Hydar

    2016-09-01

    Mast cells (MCs), which are granulated tissue-resident cells of hematopoietic lineage, contribute to vascular homeostasis, innate/adaptive immunity, and wound healing. However, MCs are best known for their roles in allergic and inflammatory diseases, such as anaphylaxis, food allergy, rhinitis, itch, urticaria, atopic dermatitis, and asthma. In addition to the high-affinity IgE receptor (FcεRI), MCs express numerous G protein-coupled receptors (GPCRs), which are the largest group of membrane receptor proteins and the most common targets of drug therapy. Antimicrobial host defense peptides, neuropeptides, major basic protein, eosinophil peroxidase, and many US Food and Drug Administration-approved peptidergic drugs activate human MCs through a novel GPCR known as Mas-related G protein-coupled receptor X2 (MRGPRX2; formerly known as MrgX2). Unique features of MRGPRX2 that distinguish it from other GPCRs include their presence both on the plasma membrane and intracellular sites and their selective expression in MCs. In this article we review the possible roles of MRGPRX2 on host defense, drug-induced anaphylactoid reactions, neurogenic inflammation, pain, itch, and chronic inflammatory diseases, such as urticaria and asthma. We propose that host defense peptides that kill microbes directly and activate MCs through MRGPRX2 could serve as novel GPCR targets to modulate host defense against microbial infection. Furthermore, mAbs or small-molecule inhibitors of MRGPRX2 could be developed for the treatment of MC-dependent allergic and inflammatory disorders.

  16. Suppression of phase transitions at low temperature by chromium substitution in vanadium spinel Fe(V1‑x Cr x )2O4

    NASA Astrophysics Data System (ADS)

    Kawaguchi, S.; Ishibashi, H.; Nagami, K.; Kubota, Y.

    2016-07-01

    Synchrotron powder diffraction, magnetization, and specific heat measurements have been used to investigate the structural and magnetic phase transitions in the spinel-type vanadate Fe(V1‑x Cr x )2O4 (0.0  ⩽  x  ⩽  1.0). We observed five different transitions in our polycrystalline samples. The canted-type ferrimagnetic phase transition accompanied by the lattice distortion was suppressed by Cr substitution (x  =  0.2). Additionally, high-resolution synchrotron powder diffraction revealed that the low-temperature orthorhombic phase appears in FeV2O4 below 30 K and disappears by subtle Cr doping. In contrast, for x  ⩾  0.7, we observed a different magnetic transition of possibly conical-type ferrimagnetic ordering that did not induce significant lattice distortion at the transition temperature. We performed structural refinements for low-temperature phases and suggest that the crystal system of Fe(V1‑x Cr x )2O4 at 15K is an orthorhombic lattice for all x values. In the orthorhombic phase, a unique behaviour was observed, with the lattice constants a and b approaching each other as Cr doping increased. This behaviour can be explained by the change of orbitally ordered states of the Fe2+ ions.

  17. Structural origin of Si-2p core-level shifts from Si(100)-c[4x2] surface: A spectral x-ray photoelectron diffraction study

    SciTech Connect

    Chen, X.; Tonner, B.P.; Denlinger, J.

    1997-04-01

    The authors have performed angle-resolved x-ray photoelectron diffraction (XPD) from a Si(100)-c(4x2) surface to study the structural origin of Si-2p core-level shifts. In the experiment, the highly resolved surface Si-2p core-level spectra were measured as a fine grid of hemisphere and photon energies, using the SpectroMicroscopy Facility {open_quotes}ultraESCA{close_quotes} instrument. By carefully decomposing the spectra into several surface peaks, the authors are able to obtain surface-atom resolved XPD patterns. Using a multiple scattering analysis, they derived a detailed atomic model for the Si(100)-c(4x2) surface. In this model, the asymmetric dimers were found tilted by 11.5 plus/minus 2.0 degrees with bond length of 2.32 plus/minus 0.05{angstrom}. By matching model XPD patterns to experiment, the authors can identify which atoms in the reconstructed surface are responsible for specific photoemission lines in the 2p spectrum.

  18. Comparison between the eruptive X2.2 flare on 2011 February 15 and confined X3.1 flare on 2014 October 24

    NASA Astrophysics Data System (ADS)

    Jing, Ju; Xu, Yan; Lee, Jeongwoo; Nitta, Nariaki V.; Liu, Chang; Park, Sung-Hong; Wiegelmann, Thomas; Wang, Haimin

    2015-09-01

    We compare two contrasting X-class flares in terms of magnetic free energy, relative magnetic helicity and decay index of the active regions (ARs) in which they occurred. The events in question are the eruptive X2.2 flare from AR 11158 accompanied by a halo coronal mass ejection (CME) and the confined X3.1 flare from AR 12192 with no associated CME. These two flares exhibit similar behavior of free magnetic energy and helicity buildup for a few days preceding them. A major difference between the two flares is found to lie in the time-dependent change of magnetic helicity of the ARs that hosted them. AR 11158 shows a significant decrease in magnetic helicity starting ∼4 hours prior to the flare, but no apparent decrease in helicity is observed in AR 12192. By examining the magnetic helicity injection rates in terms of sign, we confirmed that the drastic decrease in magnetic helicity before the eruptive X2.2 flare was not caused by the injection of reversed helicity through the photosphere but rather the CME-related change in the coronal magnetic field. Another major difference we find is that AR 11158 had a significantly larger decay index and therefore weaker overlying field than AR 12192. These results suggest that the coronal magnetic helicity and the decay index of the overlying field can provide a clue about the occurrence of CMEs.

  19. Large spontaneous exchange bias and giant magnetoresistance in Ni50Mn37-xFexIn13(x=2-4) Heusler alloys

    NASA Astrophysics Data System (ADS)

    Jing, Chao; Liu, Yang; Zheng, Dong; Wang, Xiaolong; Sun, Junkun; Zhang, Yuanlei; Liu, Changqin; Deng, Dongmei; Feng, Zhenjie; Xu, Kun; Li, Zhe

    2016-09-01

    In the present work, we have obtained a large zero-field cooled exchange-bias (spontaneous exchange bias, SEB) in Ni50Mn35Fe2In13 Heusler alloy. The experimental results indicate that the sample with x=2 exhibits super-spin glass (SSG), super-paramagnetic (SPM), super-ferromagnetic (SFM) and antiferromagnetic (AFM) behaviors in the martensite state at low temperature. Contributing to the complex magnetic interactions, a large SEB effect with the value of 1567 Oe was obtained at 5 K. At the same time, a non-monotonic behavior of spontaneous exchange bias field (spontaneous HEB) was observed with the variation of temperature, which is resulted from the competition between the volume fraction of SFM clusters and the exchange coupling of the SFM-AFM interface. In addition, during martensitic transformation (MT), extraordinary electrical transport properties of Ni50Mn37-xFexIn13 (x=2-4) alloys have been observed under various external magnetic field. The maximal value of the giant magnetoresistance (GMR) reaches about 57% at 135 K under the external magnetic field change of 50 kOe. The effect of field induced reverse martensitic transformation (FIRMT) on the GMR has been also discussed.

  20. Roles of MAS-related G protein coupled receptor-X2 (MRGPRX2) on mast cell-mediated host defense, pseudoallergic drug reactions and chronic inflammatory diseases

    PubMed Central

    Subramanian, Hariharan; Gupta, Kshitij; Ali, Hydar

    2016-01-01

    Mast cells (MCs), which are granulated tissue-resident cells of hematopoietic lineage, contribute to vascular homeostasis, innate/adaptive immunity and wound healing. MCs are, however, best known for their roles in allergic and inflammatory diseases such as anaphylaxis, food allergy, rhinitis, itch, urticaria, atopic dermatitis and asthma. In addition to the high affinity IgE receptor (FcεRI), MCs express numerous G protein coupled receptors (GPCRs), which are the largest group of membrane receptor proteins and are the most common targets of drug therapy. Antimicrobial host defense peptides (HDPs), neuropeptides (NPs), major basic protein (MBP), eosinophil peroxidase (EPO) and many FDA approved peptidergic drugs activate human MCs via a novel GPCR known as MAS-related G protein coupled receptor-X2 (MRGPRX2; formerly known as MrgX2). Unique features of MRGPRX2 that distinguish it from other GPCRs include their presence both on plasma membrane and intracellular sites and their selective expression in MCs. In this article, we review the possible roles of MRGPRX2 on host defense, drug-induced anaphylactoid reactions, neurogenic inflammation, pain, itch and chronic inflammatory diseases such as urticaria and asthma. We propose that HDPs that kill microbes directly and activate MCs via MRGPRX2 could serve as novel GPCR targets to modulate host defense against microbial infection. Furthermore, monoclonal antibodies or small molecule inhibitors of MRGPRX2 could be developed for the treatment of MC-dependent allergic and inflammatory disorders. PMID:27448446

  1. Analysis of the Rotational Structure of ˜{B}^2A' ← ˜{X}^2A' Transition of Isopropoxy Radical: Isolated State vs. Coupled States Model

    NASA Astrophysics Data System (ADS)

    Melnik, Dmitry G.; Miller, Terry A.; Liu, Jinjun

    2013-06-01

    Isopropoxy radicals are reactive intermediates in atmospheric and combustion chemistry. From the theoretical point of view, they represent an extreme case of ``isotopically'' substituted methoxy radicals with two methyl groups playing the role of heavy hydrogen isotopes. Previously the rotationally resolved spectra of ˜{B}^2A' ← ˜{X}^2A' electronic transition were successfully analyzed using a simple effective rotational Hamiltonian of the isolated ˜{X} and ˜{B} states. However, a number of the experimentally determined parameters appeared dramatically inconsistent with the quantum chemistry calculations and theoretical predictions based on the symmetry arguments. Recently, we analyzed these spectra using a coupled two state model, which explicitly includes interactions between the ground ˜{X}^2A' state and low-lying excited ˜{A}^2A^'' state. In this presentation we will discuss the results of this analysis and compare the parameters of both models and their physical significance. D. G. Melnik, T. A. Miller and J. Liu, TI15, 67^{th Molecular Spectroscopy Symposium}, Columbus, 2012

  2. Roles of Mas-related G protein-coupled receptor X2 on mast cell-mediated host defense, pseudoallergic drug reactions, and chronic inflammatory diseases.

    PubMed

    Subramanian, Hariharan; Gupta, Kshitij; Ali, Hydar

    2016-09-01

    Mast cells (MCs), which are granulated tissue-resident cells of hematopoietic lineage, contribute to vascular homeostasis, innate/adaptive immunity, and wound healing. However, MCs are best known for their roles in allergic and inflammatory diseases, such as anaphylaxis, food allergy, rhinitis, itch, urticaria, atopic dermatitis, and asthma. In addition to the high-affinity IgE receptor (FcεRI), MCs express numerous G protein-coupled receptors (GPCRs), which are the largest group of membrane receptor proteins and the most common targets of drug therapy. Antimicrobial host defense peptides, neuropeptides, major basic protein, eosinophil peroxidase, and many US Food and Drug Administration-approved peptidergic drugs activate human MCs through a novel GPCR known as Mas-related G protein-coupled receptor X2 (MRGPRX2; formerly known as MrgX2). Unique features of MRGPRX2 that distinguish it from other GPCRs include their presence both on the plasma membrane and intracellular sites and their selective expression in MCs. In this article we review the possible roles of MRGPRX2 on host defense, drug-induced anaphylactoid reactions, neurogenic inflammation, pain, itch, and chronic inflammatory diseases, such as urticaria and asthma. We propose that host defense peptides that kill microbes directly and activate MCs through MRGPRX2 could serve as novel GPCR targets to modulate host defense against microbial infection. Furthermore, mAbs or small-molecule inhibitors of MRGPRX2 could be developed for the treatment of MC-dependent allergic and inflammatory disorders. PMID:27448446

  3. A study of temperature dependent local atomic displacements in a Ba(Fe(1-x)Co(x))2As2 superconductor.

    PubMed

    Hacisalihoglu, M Y; Paris, E; Joseph, B; Simonelli, L; Sato, T J; Mizokawa, T; Saini, N L

    2016-04-01

    We have studied the local structure of a Ba(Fe(1-x)Co(x))2As2 superconductor using temperature dependent extended X-ray absorption fine structure (EXAFS) measurements. Polarized EXAFS at the Fe K-edge on an optimally doped (x = 0.06) single crystal has permitted us to determine atomic displacements across the superconducting transition temperature (T(c)). The Fe-As bondlength hardly shows any change with temperature; however, the Fe-Fe sublattice reveals a sharp anomaly across T(c), indicated by a significant drop in mean square relative displacements, similar to the one known for cuprates and A15-type superconductors. We have also found a large atomic disorder around the substituted Co, revealed by polarized Co K-edge EXAFS measurements. The Co-Fe/Co bonds are more flexible than the Fe-Fe bonds with the As-height in Co-containing tetrahedra being larger than the one in FeAs4. The results suggest that the local Fe-Fe bondlength fluctuations and the atomic disorder in this sub-lattice should have some important role in the superconductivity of Ba(Fe(1-x)Co(x))2As2 pnictides.

  4. Suppression of phase transitions at low temperature by chromium substitution in vanadium spinel Fe(V1-x Cr x )2O4.

    PubMed

    Kawaguchi, S; Ishibashi, H; Nagami, K; Kubota, Y

    2016-07-27

    Synchrotron powder diffraction, magnetization, and specific heat measurements have been used to investigate the structural and magnetic phase transitions in the spinel-type vanadate Fe(V1-x Cr x )2O4 (0.0  ⩽  x  ⩽  1.0). We observed five different transitions in our polycrystalline samples. The canted-type ferrimagnetic phase transition accompanied by the lattice distortion was suppressed by Cr substitution (x  =  0.2). Additionally, high-resolution synchrotron powder diffraction revealed that the low-temperature orthorhombic phase appears in FeV2O4 below 30 K and disappears by subtle Cr doping. In contrast, for x  ⩾  0.7, we observed a different magnetic transition of possibly conical-type ferrimagnetic ordering that did not induce significant lattice distortion at the transition temperature. We performed structural refinements for low-temperature phases and suggest that the crystal system of Fe(V1-x Cr x )2O4 at 15K is an orthorhombic lattice for all x values. In the orthorhombic phase, a unique behaviour was observed, with the lattice constants a and b approaching each other as Cr doping increased. This behaviour can be explained by the change of orbitally ordered states of the Fe(2+) ions.

  5. Regulation of the stability of poly(I)xpoly(C)-induced human fibroblast interferon mRNA: selective inactivation of interferon mRNA and lack of involvement of 2',5'-oligo(A) synthetase activation during the shutoff of interferon production.

    PubMed

    Sehgal, P B; Gupta, S L

    1980-06-01

    The inactivation of interferon mRNA during the shutoff phase of interferon production in poly(I)xpoly(C)-induced human fibroblast cultures is selective. We have determined that the shutoff of interferon production, which takes place from 3 to 8 hr after the beginning of induction, is not associated with an appreciable declined in the rate of bulk cellular protein synthesis or of cellular protein secretion. While the amount of translatable interferon mRNA declined markedly during the shutoff phase, the level of translatable bulk cellular mRNA and the stability of [3H]uridine-labeled mRNA were unaffected. Superinduction with actinomycin D selectively stabilized interferon mRNA with no apparent effect on the stability of bulk cellular mRNA. Furthermore, an activation of the 2',5'-oligo(A) synthetase/endonuclease system does not appear to be involved in the shutoff phenomenon. Uninduced FS-4 cells contained a low basal level of 2'5'-oligo(A) synthetase activity, which was unchanged in poly(I)xpoly(C)-induced cells during the shutoff phase. Treatment of FS-4 cells with interferon for 16-18 hr prior to induction increased the enzyme activity by approximately 200-fold. However, this did not inhibit interferon production after induction with poly(I)xpoly(C) alone or after superinduction with cycloheximide or actinomycin D or both. Furthermore, the rates of decay of interferon production were comparable in cells with either a basal or an increased level of 2',5'-oligo(A) synthetase. Thus a 200-fold increase in 2',5'-oligo(A) synthetase level did not affect either the stability of interferon mRNA or the efficacy of interferon superinduction by metabolic inhibitors.

  6. A comprehensive model for the quantification of linear and nonlinear regime laser-induced fluorescence of OH under A2Σ+←X2Π(1,0) excitation

    NASA Astrophysics Data System (ADS)

    Dunn, M. J.; Masri, A. R.

    2010-10-01

    An analytic model termed the ‘integrated quasi-steady-state’ (IQSS) model for the comprehensive quantification of both linear and nonlinear regime laser-induced fluorescence (LIF) is presented. The IQSS model is optimized for the hydroxyl radical (OH), subject to nanosecond A2Σ+←X2Π(1,0) excitation at pressures close to atmospheric. The IQSS model is particularly relevant to experimental conditions where the LIF signal is both spectrally and temporally integrated, such as in planar laser-induced fluorescence experiments. The IQSS model is based around a quasi-steady-state solution to a four-level rate-equation approximation of the OH molecule; this quasi-steady-state solution is then integrated with a triangular functional form for both the spatial and temporal variations to produce an analytic solution. In order to accurately predict LIF in the nonlinear regime, it is shown that both the temporal and the spatial variations of the laser pulse—or ‘wings’ of the laser pulse—must be adequately accounted for in the LIF model formulation. The IQSS model is successfully verified against detailed numerical simulations for variations in the laser irradiance, quenching environment and temperature. Experimentally, the IQSS model is successfully validated by comparing the predicted and measured OH LIF vs. irradiance dependence in the product gases of a methane-air laminar flame.

  7. Evaluation of BC2 progenies derived from 3x-2x and 3x-4x crosses of Lilium hybrids: a GISH analysis.

    PubMed

    Lim, K-B; Ramanna, M S; Jacobsen, E; van Tuyl, J M

    2003-02-01

    An allotriploid (ALA, 2n=3 x=36) BC(1) plant was obtained by backcrossing a diploid F(1) interspecific hybrid (LA, 2n=2 x=24), derived from a Lilium longiflorum (L genome) and an Asiatic hybrid (A genome), to the latter parent. This allotriploid was backcrossed to a diploid Asiatic hybrid (2n=2 x=24) and to an allotetraploid (LLAA, 2n=4 x=48) LA hybrid. A total of 25 plants of these crosses were examined for ploidy level, and 12 individuals were analyzed for their genome constitution through genomic in situ hybridization (GISH). In most cases the progenies from the triploid-diploid (3 x-2 x) crosses consisted of aneuploids. Further more, there was evidence for the formation of near-haploid (x=12+2) to triploid (3 x=36) gametes in the allotriploid BC(1) plant. The progenies of triploid-tetraploid (3 x-4 x) cross also consisted of mostly aneuploids but in this case the triploid female parent had contributed predominantly near-triploid (2n) gametes for the origin of BC(2) progenies. The different ploidy levels observed between 3 x-2 x and 3 x-4 x crosses are possibly caused by preferential fertilization or survival resulting in a different ratio of chromosome numbers between the embryo and endosperm. Though Lilium has a tetrasporic, eight-nucleate type of embryo sac formation (Fritillaria type), the observed difference between the progeny types in 3 x-2 x and 3 x-4 x crosses is comparable to that of observed in monosporic eight nucleate types (Polygonum type) that predominate in most genera of Angiosperms. An important feature of the genome constitution of the progenies was that the homoeologous recombinant chromosomes were transmitted intact from BC(1) to BC(2) progenies in variable numbers. In addition, there was evidence for the occurrence of new homoeologous recombinations in the triploid BC(1). Of the two euploid BC(2) plants one had originated through the parthenogenetic development of a 2n egg and the other had originated through indeterminate meiotic

  8. Born-Oppenheimer and Renner-Teller coupled-channel quantum reaction dynamics of O((3)P) + H2(+)(X(2)Σg(+)) collisions.

    PubMed

    Gamallo, Pablo; Defazio, Paolo; González, Miguel; Paniagua, Miguel; Petrongolo, Carlo

    2015-09-28

    We present Born-Oppenheimer (BO) and Renner-Teller (RT) time dependent quantum dynamics studies of the reactions O((3)P) + H2(+)(X(2)Σg(+)) → OH(+)(X(3)Σ(-)) + H((2)S) and OH(X(2)Π) + H(+). We consider the OH2(+) X[combining tilde](2)A'' and Ã(2)A' electronic states that correlate with a linear (2)Π species. The electronic angular momenta operators L[combining circumflex] and L[combining circumflex](2) are considered in nonadiabatic coupled-channel calculations, where the associated RT effects are due to diagonal V(RT) potentials that add up to the PESs and to off-diagonal C(RT) couplings between the potential energy surfaces (PESs). Initial-state-resolved reaction probabilities PI, integral cross sections σI, and rate constants kI are obtained using recent ab initio PESs and couplings and the real wavepacket formalism. Because the PESs are strongly attractive, PI have no threshold energy and are large, σI decrease with collision energy, and kI depend little on the temperature. The X[combining tilde](2)A'' PES is up to three times more reactive than the Ã(2)A' PES and H2(+) rotational effects (j0 = 0, 1) are negligible. The diagonal V(RT) potentials are strongly repulsive at the collinearity and nearly halve all low-energy observables with respect to the BO ones. The off-diagonal C(RT) couplings are important at low partial waves, where they mix the X[combining tilde](2)A'' and Ã(2)A' states up to ∼20%. However, V(RT) effects predominate over the C(RT) ones that change at most by ∼19% the BO values of σI and kI. The reaction O((3)P) + H2(+)(X(2)Σg(+)) → OH(+)(X(3)Σ(-)) + H((2)S) is probably one of the most reactive atom + diatom collisions because its RT rate constant at room temperature is equal to 2.26 × 10(-10) cm(3) s(-1). Within the BO approximation, the present results agree rather well with recent quasiclassical and centrifugal-sudden data using the same PESs.

  9. Composition determination of β-(Al x Ga1‑ x )2O3 layers coherently grown on (010) β-Ga2O3 substrates by high-resolution X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Oshima, Yuichi; Ahmadi, Elaheh; Badescu, Stefan C.; Wu, Feng; Speck, James S.

    2016-06-01

    We demonstrate X-ray-diffraction-based composition estimation of β-(Al x Ga1‑ x )2O3 coherently grown on (010) β-Ga2O3. The relation between the strain along the [010] direction and the Al composition of the β-(Al x Ga1‑ x )2O3 layer was formulated using the stress–strain relationship in the monoclinic system. This formulation allows us to estimate the Al composition using the out-of-plane lattice spacing determined by conventional X-ray ω–2θ measurements. This method was applied to molecular-beam-epitaxy-grown coherent β-(Al x Ga1‑ x )2O3/Ga2O3 heterostructures, and the Al composition in β-(Al x Ga1‑ x )2O3 agrees closely with the composition determined directly by atom probe tomography.

  10. First-Principles Study of Antimony Doping Effects on the Iron-Based Superconductor CaFe(SbxAs1-x)2

    NASA Astrophysics Data System (ADS)

    Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; Kuroki, Kazuhiko

    2015-09-01

    We study antimony doping effects on the iron-based superconductor CaFe(SbxAs1-x)2 by using the first-principles calculation. The calculations reveal that the substitution of a doped antimony atom into As of the chainlike As layers is more stable than that into FeAs layers. This prediction can be checked by experiments. Our results suggest that doping homologous elements into the chainlike As layers, which only exist in the novel 112 system, is responsible for rising up the critical temperature. We discuss antimony doping effects on the electronic structure. It is found that the calculated band structures with and without the antimony doping are similar to each other within our framework.

  11. Untangling the reaction dynamics of the silylidyne radical (SiH; X2Π) with acetylene (C2H2; X1Σg+)

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Dangi, Beni B.; Thomas, Aaron M.; Kaiser, Ralf I.

    2016-06-01

    The chemical reaction dynamics of silylidyne (SiH; X2Π) with acetylene (C2H2; X1Σg+) were studied exploiting the crossed molecular beam approach, and compared with previous studies on D1-silylidyne with acetylene. The reaction is initiated by a barrierless addition of silylidyne to one or both carbons of acetylene leading to 1-sila-1-propene-1,3-diylidene and/or the cyclic 1-silacyclopropenyl with the former isomerizing to the latter. 1-Silacyclopropenyl eventually loses atomic hydrogen yielding silacyclopropenylidene (c-SiC2H2) in an overall exoergic reaction (experiment: -14.7 ± 8.5 kJ mol-1; theory: -13 ± 3 kJ mol-1). The enthalpy of formation for silacyclopropenylidene is determined to be 421.4 ± 9.3 kJ mol-1.

  12. Morphotropic phase boundary, weak ferromagnetism, and strong piezoelectric effect in Bi{sub 1-x}Ca{sub x}FeO{sub 3-x/2} compounds

    SciTech Connect

    Troyanchuk, I. O. Karpinsky, D. V.; Bushinsky, M. V.; Kovetskaya, M. I.; Efimova, E. A.; Eremenko, V. V.

    2011-12-15

    The crystal structure and magnetic and piezoelectric properties of the Bi{sub 1-x}Ca{sub x}FeO{sub 3-x/2} system (x {<=} 0.2) are studied. The crystal-structure transformations occur in the following sequence: rhombohedral (R3c) polar phase (x {<=} 0.06) {yields} modulated polar phase (0.07 {<=} x {<=} 0.1) {yields} modulated antipolar phase (0.11 {<=} x {<=} 0.14). The modulated polar and antipolar phases are weakly ferromagnetic with a spontaneous magnetization of 0.25 G cm{sup 3}/g (x = 0.09). In the polar weak ferromagnet with x = 0.09, a uniform piezoelec- tric response 2.5 times stronger than in the initial BiFeO{sub 3} compound is detected by the piezoelectric force microscopy.

  13. Crystal structure and magnetic properties of new Fe3Co3 X 2 (X  =  Ti, Nb) intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Nguyen, Manh Cuong; Balasubramanian, Balamurugan; Das, Bhaskar; Sellmyer, David J.; Zeng, Zhi; Ho, Kai-Ming; Wang, Cai-Zhuang

    2016-05-01

    The structure and magnetic properties of new magnetic Fe3Co3 X 2 (X  =  Ti, Nb) compounds are studied by genetic algorithm, first-principles density functional theory (DFT) calculations, and experiments. The atomic structure of a hexagonal structure with P-6m2 symmetry is determined. The simulated x-ray diffraction (XRD) spectra of the P-6m2 structures agree well with experimental XRD data for both Fe3Co3Ti2 and Fe3Co3Nb2. The magnetic properties of these structures as well as the effect of the disorder of Fe and Co on their magnetic properties are also investigated. The magnetocrystalline anisotropy energy is found to be very sensitive to the occupancy disorder between Fe and Co.

  14. Thermodynamic studies on the ferroelectric phase transition in neutron irradiated (Li(sub x)K(1-x))2SO4 crystals at high temperature

    NASA Astrophysics Data System (ADS)

    Kassem, M. E.; El-Khatib, A. M.; Ammar, E. A.; Denton, M. M.

    1989-05-01

    Thermodynamic studies of (Li(x)K(1-x))2SO4, LKS, mixed crystals have been made in the concentration range (x=0.1,0.2,..., x=0.5). The thermal behavior has been investigated by differential thermal analysis, DTA, and differential scanning calorimeter, DSC, in the vicinity of high temperature phases. Also, the effect of the mixed neutron field of fast and thermal neutrons (10 percent of the reactor neutron pile is fast neutrons) on the thermal properties of mixed crystals was studied. The results show a change in the transition temperature Tc, as well as the value of specific heat Cp at transition temperature, due to the change of the stoichiometric ratio and the radiation doses. The changes of enthalpy and entropy of mixed crystals have been estimated numerically. The obtained small values of Delta S/R is characteristic of incommensurate phase transition as previously confirmed by the results of neutron diffraction technique.

  15. The [17.0] 2Π1/2← X 2Π1/2 system of AlCa

    NASA Astrophysics Data System (ADS)

    Fabbi, Jacqueline C.; Langenberg, Jon D.; Morse, Michael D.

    2000-04-01

    Laser-induced fluorescence spectroscopy has been used to study supersonically cooled AlCa. This study investigates under higher resolution (0.007 cm-1) a single band previously studied and tentatively assigned as the (0-0) vibrational transition of the [17.0] 2Δ3/2(?)← X 2Π1/2 system of AlCa. The resolution of the rotational structure in the present study enabled a definite assignment as a 2Π1/2← 2Π1/2 transition. Analysis of the spectrum gives B0'=0.096685(19) cm-1, ( p+2 q)'=-0.013078(370) cm -1, and B0″=0.105518(20) cm -1. These convert to ground and excited state bond lengths of r0″=3.14942(30) and r0'=3.29014(32) Å, respectively.

  16. Recovery of citrus triploid hybrids by embryo rescue and flow cytometry from 2x x 2x sexual hybridisation and its application to extensive breeding programs.

    PubMed

    Aleza, P; Juárez, J; Cuenca, J; Ollitrault, P; Navarro, Luis

    2010-09-01

    Seedlessness is one of the most important characteristics for mandarins for the fresh-fruit market and mandarin triploid hybrids have this trait. Citrus triploid plants can be recovered by 2x x 2x sexual hybridisations as a consequence of the formation of unreduced gametes at low frequency. Triploid embryos are found in small seeds that do not germinate under greenhouse conditions. Extensive breeding programs based on this type of hybridisation require very effective methodologies for embryo rescue and ploidy evaluation. In this work, we describe an effective methodology to recover triploid hybrids from 2x x 2x hybridisations based on in vitro embryo rescue and ploidy level determination by means of flow cytometry. The influence of parents and environmental conditions on obtaining triploid hybrids has been analysed. The strongest effect was associated with the genotype of the female parent while a strong interaction was found between the male parent genotype and environmental conditions. The effect of the female parent genotype on the length of the juvenile phase was also demonstrated by observing a large number of progenies over the last 10 years. The methodology described here has enabled us to obtain over 4,000 triploid hybrids so far, of which 13 have been protected in the European Union and two are being extensively planted by citrus growers to establish new commercial plots. These triploid hybrids have been analysed with simple sequence repeats markers to differentiate all the new triploid varieties and their parents, and thus molecular identification will help defend plant breeders' rights.

  17. Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX2(pyz)2 (X = Cl, Br, I, NCS; pyz = Pyrazine).

    PubMed

    Liu, Junjie; Goddard, Paul A; Singleton, John; Brambleby, Jamie; Foronda, Francesca; Möller, Johannes S; Kohama, Yoshimitsu; Ghannadzadeh, Saman; Ardavan, Arzhang; Blundell, Stephen J; Lancaster, Tom; Xiao, Fan; Williams, Robert C; Pratt, Francis L; Baker, Peter J; Wierschem, Keola; Lapidus, Saul H; Stone, Kevin H; Stephens, Peter W; Bendix, Jesper; Woods, Toby J; Carreiro, Kimberly E; Tran, Hope E; Villa, Cecelia J; Manson, Jamie L

    2016-04-01

    The crystal structures of NiX2(pyz)2 (X = Cl (1), Br (2), I (3), and NCS (4)) were determined by synchrotron X-ray powder diffraction. All four compounds consist of two-dimensional (2D) square arrays self-assembled from octahedral NiN4X2 units that are bridged by pyz ligands. The 2D layered motifs displayed by 1-4 are relevant to bifluoride-bridged [Ni(HF2)(pyz)2]EF6 (E = P, Sb), which also possess the same 2D layers. In contrast, terminal X ligands occupy axial positions in 1-4 and cause a staggered packing of adjacent layers. Long-range antiferromagnetic (AFM) order occurs below 1.5 (Cl), 1.9 (Br and NCS), and 2.5 K (I) as determined by heat capacity and muon-spin relaxation. The single-ion anisotropy and g factor of 2, 3, and 4 were measured by electron-spin resonance with no evidence for zero-field splitting (ZFS) being observed. The magnetism of 1-4 spans the spectrum from quasi-two-dimensional (2D) to three-dimensional (3D) antiferromagnetism. Nearly identical results and thermodynamic features were obtained for 2 and 4 as shown by pulsed-field magnetization, magnetic susceptibility, as well as their Néel temperatures. Magnetization curves for 2 and 4 calculated by quantum Monte Carlo simulation also show excellent agreement with the pulsed-field data. Compound 3 is characterized as a 3D AFM with the interlayer interaction (J⊥) being slightly stronger than the intralayer interaction along Ni-pyz-Ni segments (J(pyz)) within the two-dimensional [Ni(pyz)2](2+) square planes. Regardless of X, J(pyz) is similar for the four compounds and is roughly 1 K.

  18. Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX2(pyz)2 (X = Cl, Br, I, NCS; pyz = Pyrazine).

    PubMed

    Liu, Junjie; Goddard, Paul A; Singleton, John; Brambleby, Jamie; Foronda, Francesca; Möller, Johannes S; Kohama, Yoshimitsu; Ghannadzadeh, Saman; Ardavan, Arzhang; Blundell, Stephen J; Lancaster, Tom; Xiao, Fan; Williams, Robert C; Pratt, Francis L; Baker, Peter J; Wierschem, Keola; Lapidus, Saul H; Stone, Kevin H; Stephens, Peter W; Bendix, Jesper; Woods, Toby J; Carreiro, Kimberly E; Tran, Hope E; Villa, Cecelia J; Manson, Jamie L

    2016-04-01

    The crystal structures of NiX2(pyz)2 (X = Cl (1), Br (2), I (3), and NCS (4)) were determined by synchrotron X-ray powder diffraction. All four compounds consist of two-dimensional (2D) square arrays self-assembled from octahedral NiN4X2 units that are bridged by pyz ligands. The 2D layered motifs displayed by 1-4 are relevant to bifluoride-bridged [Ni(HF2)(pyz)2]EF6 (E = P, Sb), which also possess the same 2D layers. In contrast, terminal X ligands occupy axial positions in 1-4 and cause a staggered packing of adjacent layers. Long-range antiferromagnetic (AFM) order occurs below 1.5 (Cl), 1.9 (Br and NCS), and 2.5 K (I) as determined by heat capacity and muon-spin relaxation. The single-ion anisotropy and g factor of 2, 3, and 4 were measured by electron-spin resonance with no evidence for zero-field splitting (ZFS) being observed. The magnetism of 1-4 spans the spectrum from quasi-two-dimensional (2D) to three-dimensional (3D) antiferromagnetism. Nearly identical results and thermodynamic features were obtained for 2 and 4 as shown by pulsed-field magnetization, magnetic susceptibility, as well as their Néel temperatures. Magnetization curves for 2 and 4 calculated by quantum Monte Carlo simulation also show excellent agreement with the pulsed-field data. Compound 3 is characterized as a 3D AFM with the interlayer interaction (J⊥) being slightly stronger than the intralayer interaction along Ni-pyz-Ni segments (J(pyz)) within the two-dimensional [Ni(pyz)2](2+) square planes. Regardless of X, J(pyz) is similar for the four compounds and is roughly 1 K. PMID:27002487

  19. Quantum scattering studies of the Λ doublet resolved rotational energy transfer of OH(X 2Π) in collisions with He and Ar

    NASA Astrophysics Data System (ADS)

    Esposti, Alessandra Degli; Berning, Andreas; Werner, Hans-Joachim

    1995-08-01

    Three dimensional potential energy surfaces for the collision systems OH(X 2Π)+He and OH(X 2Π)+Ar have been calculated using the coupled electron pair approximation (CEPA) and large basis sets. The asymptotically degenerate 2Πx and 2Πy states split into two states of 2A' and 2A″ symmetry, respectively, when the C∞v symmetry is lifted by the approach of the noble gas atom. The average and half difference of the calculated points on the A″ and A' potential energy surfaces were fitted to analytical functions, which were then vibrationally averaged. These potential energy surfaces have been used in quantum scattering calculations of cross sections for collision induced rotationally inelastic transitions. Test calculations showed that the cross sections obtained from exact close-coupling calculations (CC) and within the coupled states approximation (CS) are in close agreement for these systems, and therefore the CS approximation has been used in all further calculations. Rotational transitions with Λ doublet resolution show, within the same spin-orbit manifold and at low collision energies, a propensity to populate preferentially the e final levels in the F1(2Π3/2) state and an e/f conserving propensity in the F2(2Π1/2) state, while transitions between the two spin-orbit manifolds show a parity conserving propensity. For the v=2 vibrational level kinetic rate coefficients were calculated for a large range of temperatures. The calculated cross sections are in excellent agreement with recent measurements of Schreel, Schleipen, Epping, and ter Meulen.

  20. Electronic structure and thermoelectric properties of (Mg2X)2 / (Mg2Y)2 (X, Y = Si, Ge, Sn) superlattices from first-principle calculations

    NASA Astrophysics Data System (ADS)

    Guo, San-Dong

    2016-05-01

    To identify thermoelectric materials containing abundant, low-cost and non-toxic elements, we have studied the electronic structures and thermoelectric properties of (Mg2X)2/ (Mg2Y)2 (X, Y = Si, Ge, Sn) superlattices with state-of-the-art first-principles calculations using a modified Becke and Johnson (mBJ) exchange potential. Our results show that (Mg2Ge)2/ (Mg2Sn)2 and (Mg2Si)2/ (Mg2Sn)2 are semi-metals using mBJ plus spin-orbit coupling (mBJ + SOC), while (Mg2Si)2/ (Mg2Ge)2 is predicted to be a direct-gap semiconductor with a mBJ gap value of 0.46 eV and mBJ + SOC gap value of 0.44 eV. Thermoelectric properties are predicted by through solving the Boltzmann transport equations within the constant scattering time approximation. It is found that (Mg2Si)2/ (Mg2Ge)2 has a larger Seebeck coefficient and power factor than (Mg2Ge)2/ (Mg2Sn)2 and (Mg2Si)2/ (Mg2Sn)2 for both p-type and n-type doping. The detrimental influence of SOC on the power factor of p-type (Mg2X)2/ (Mg2Y)2 (X, Y = Si, Ge, Sn) is analyzed as a function of the carrier concentration, but there is a negligible SOC effect for n-type. These results can be explained by the influence of SOC on their valence and conduction bands near the Fermi level.

  1. Photoluminescence of A- and B-site Eu3+-substituted (SrxBa1-x)2CaWyMo1-yO6 phosphors

    NASA Astrophysics Data System (ADS)

    Sletnes, M.; Lindgren, M.; Valmalette, J. C.; Wagner, N. P.; Grande, T.; Einarsrud, M.-A.

    2016-05-01

    The photoluminescence of two series of A- and B-site Eu3+ substituted (SrxBa1-x)2CaWyMo1-yO6 double perovskite phosphor materials, (SrxBa1-x)1.96Eu0.02K0.02CaWyMo1-yO6 and (SrxBa1-x)2Ca0.96Eu0.02Li0.02WyMo1-yO6 (x and y=0, 0.25, 0.50, 0.75, and 1), were studied systematically as a function of stoichiometry and crystal structure. The Eu3+ lattice sites controlled by co-doping with either K or Li were confirmed by Raman spectroscopy. The variation in integrated emission intensity and emission colour over the experimental matrix was examined using statistical tools, and the observed trends were rationalized based on the physical and electronic structure of the phosphors. Phosphors with Eu on B-site with maximum Sr content had remarkably higher emission intensities than all other materials, but the emission was more orange than red due to domination of the 5D0-7F1 (595 nm) transition of Eu3+. The relative intensities of the 5D0-7F2 (615 nm) and 5D0-7F1 transitions of Eu3+, and thus the red-shift of the emission, decreased linearly with increasing Sr content in the A-site Eu-substituted phosphors, and reached a maximum for Sr1.96Eu0.02K0.02CaW0.25Mo0.75O6. A maximum external quantum efficiency of 17% was obtained for the phosphor Sr2Ca0.7Eu0.15Li0.15W0.5Mo0.5O6 with Eu on B-site.

  2. The Conterminous United States Mineral Assessment Program; background information to accompany folio of geologic, geochemical, remote sensing, and mineral resources maps of the Butte 1 degree x 2 degrees Quadrangle, Montana

    USGS Publications Warehouse

    Elliott, James E.; Trautwein, C.M.; Wallace, C.A.; Lee, G.K.; Rowan, L.C.; Hanna, W.F.

    1993-01-01

    The Butte 1?x2 ? quadrangle in west-central Montana was investigated as part of the U.S. Geological Survey's Conterminous United States Mineral Assessment Program (CUSMAP). These investigations included geologic mapping, geochemical surveys, gravity and aeromagnetic surveys, examinations of mineral deposits, and specialized geochronologic and remote-sensing studies. The data collected during these studies were compiled, combined with available published and unpublished data, analyzed, and used in a mineral-resource assessment of the quadrangle. The results, including data, interpretations, and mineral-resource assessments for nine types of mineral deposits, are published separately as a folio of maps. These maps are accompanied by figures, tables, and explanatory text. This circular provides background information on the Butte quadrangle, summarizes the studies and published maps, and lists a selected bibliography of references pertinent to the geology, geochemistry, geophysics, and mineral resources of the quadrangle. The Butte quadrangle, which includes the world-famous Butte mining district, has a long history of mineral production. Many mining districts within the quadrangle have produced large quantities of many commodities; the most important in dollar value of production were copper, gold, silver, lead, zinc, manganese, molybdenum, and phosphate. At present, mines at several locations produce copper, molybdenum, gold, silver, lead, zinc, and phosphate. Exploration, mainly for gold, has indicated the presence of other mineral deposits that may be exploited in the future. The results of the investigations by the U.S. Geological Survey indicate that many areas of the quadrangle are highly favorable for the occurrence of additional undiscovered resources of gold, silver, copper, molybdenum, tungsten, and other metals in several deposit types.

  3. Dispersed Fluorescence Spectroscopy of the ˜{B} ^2E' - ˜{X} ^2A_2' Transition of Jet Cooled ^{14}NO_3 and ^{15}NO_3

    NASA Astrophysics Data System (ADS)

    Fukushima, Masaru; Ishiwata, Takashi

    2013-06-01

    We have generated NO_3 in supersonic free jet expansions and observed laser induced fluorescence ( LIF ) of the ˜{B} ^2E' - ˜{X} ^2A_2' transition. We have measured LIF excitation spectra and dispersed fluorescence ( DF ) spectra from the single vibronic levels ( SVL's ) of the ˜{B} ^2E' state of ^{14}NO_3 and ^{15}NO_3. The vibrational structure of the ˜{X} ^2A_2' state has been analyzed by comparing the vibrational structures of the DF spectra of the two isotopomers. The 1,053 cm^{-1} band of ^{14}NO_3 is observed as two bands at 1,039 and 1,053 cm^{-1} with an intensity ratio of 4 : 5, respectively, for ^{15}NO_3, which are observed in the DF spectra with our standard resolution ( ˜ 7 cm^{-1} in FWHM ). Higher resolution measurements ( ˜ 2 cm^{-1} in FWHM ) of the DF spectra show that the 1,053 cm^{-1} band of ^{14}NO_3 is also observed as two bands at 1,051 and 1,056 cm^{-1} with an intensity ratio of 5 : 3, respectively. The 1,051 cm^{-1} band is attributed to be the ν_1 ( a_1' ) fundamental, because of its little isotope shift. There are two possibilities for another band, the band at 1,056 and 1,038 cm^{-1} for ^{14}NO_3 and ^{15}NO_3, respectively; (1) the ν_3 ( e' ) fundamental band, and (2) the ν_2 + ν_4 ( a_2'' and e', respectively ) combination band. If this is the case (1), the ν_3 band should be observed in IR spectrum, but it has yet to be observed. If (2), the intensity must be stolen from the ˜{B} ^2E' - ˜{A} ^2E'' transition through the ν_2 mode, the considerable transition moment of which has been predicted. A simple consideration for the vibronic coupling between the ˜{A} ^2E'' and ˜{X} ^2A_2' states through the ν_2 mode can understand about 20 % of the combination band intensity to that of the ν_1 fundamental. The higher resolution measurements of the DF spectra also show that the 1,499 cm^{-1} band of ^{14}NO_3 is much stronger than the 1,492 cm^{-1} band in the electronic spectrum, while the latter is the strongest band in

  4. Theoretical study of hyperfine coupling constants and electron spin g factors for X2Σ diatomics from Groups 1 and 2

    NASA Astrophysics Data System (ADS)

    Bruna, Pablo J.; Grein, Friedrich

    The ESR parameters of the cations Be 2 + , Mg 2 + , Ca 2 + , BeMg + , BeCa + , MgCa + and the mixed radicals ZBe, ZMg, ZCa (Z = Li, Na, K), all having a X 2 Σu + (1 σg 2 1 σu )/X 2 Sigma + (1 σ2 2 σ) ground state, have been studied theoretically. The A iso and A dip constants have been calculated with UHF, CISD, MP2, B3LYP, PW91PW91 wavefunctions, and 6-311+G(2df) basis sets. The electron spin g factors (magnetic moment μs) have been evaluated from correlated (MRDCI) wavefunctions, using a Hamiltonian based on Breit-Pauli theory with perturbation expansions up to second order, and 6-311+ G(2d) basis sets. As expected for s-rich radicals, the hyperfine spectra are governed by the A iso terms. Both Δg|| and Δg Υ̂values are negative, but Δg|| lies close to zero. For Δg Υ̂, the coupling with 1 2 Π(u) dominates the sum-over-states expansions. Although the singly occupied MOs (SOMO) are mostly of s character, the | Δg Υ̂| are relatively large, up to 5200 ppm for cationic, and up to 7850 ppm for neutral radicals. These large values are caused by low excitation energies and high magnetic transition moments, the latter due to the fact that the σ*( s - s ) SOMO has the same nodal properties as a p σorbital. Of the radicals considered here, an ESR spectrum is available only for Mg2+. Our theoretical A iso of-287 MHz reproduces well the matrix result (-291 MHz). Calculated values of-10 ppm for Deltag|| and of-1280 ppm for Deltag Υ̂give an average < Δg> =-860 ppm that lies within the experimental range of-600( ±300) ppm in Ne, and of-1300( ±500) ppm in Ar matrices.

  5. Maps showing interpretation, using R-mode factor analysis, of trace-element abundances in heavy-mineral concentrate samples, Delta 1° x 2° Quadrangle, Utah

    USGS Publications Warehouse

    Zimbelman, David R.

    1994-01-01

    A set of heavy-mineral concentrate data for the Delta 1° x 2° quadrangle, Utah Conterminous U.S. Mineral Assessment Program (CUSMAP) project was compiled from results of analyses of samples collected during the National Uranium Resource Evaluation Program (SURE), as well as results obtained from samples collected more recently by the USGS. Data results, sampling methods, and analytical methods are provided in Abrogast and others, 1993; 1990; 1988a; 1988b). A similar report, discussing results obtained from stream-sediment samples, is presented in Zimbelman (1993a). The Delta 1° x 2° quadrangle, Utah (figure 1) contains a variety of hydrothermal mineral deposit types, including porphyry-, vein-, replacement-, and Carlin-type deposits. These deposit types have been worked for commodities including gold, silver, beryllium, uranium, lead, zinc, copper, manganese, and cadmium (Lindsey, 1977; Morris and Mogensen, 1978; Zimbelman and others, 1990; Zimbelman and others, 1988). Heavy-mineral concentrate and stream-sediment samples derived from these hydrothermally altered rocks typically contain many geochemical anomalies (for example, see Zimbelman 1993b, c, d). Element associations characterizing lithology and hydrothermal mineral deposits can be distinguished using R-mode factor analysis. This tool often is useful in reconnaissance-scale surveys where sample anomalies are often weak. and single-element distributions may not help to delineate targets. R-mode factors analysis can help identify geologic trends and areas most likely to contain the mineral deposits. R-mode factor analysis was performed on a data set of results of analyses for 19 elements in 643 samples and produced a six-factor model. These six factors represent the geochemical contributions to the data set provided by lithologic and mineralization processes, The distribution of samples that contain high scores for mineralization-related factors is widespread in the Delta quadrangle. These sample sites

  6. Patterns of expression of messenger RNAs encoding GDF9, BMP15, TGFBR1, BMPR1B, and BMPR2 during follicular development and characterization of ovarian follicular populations in ewes carrying the Woodlands FecX2W mutation.

    PubMed

    Feary, Elisabeth S; Juengel, Jennifer L; Smith, Peter; French, Michelle C; O'Connell, Anne R; Lawrence, Stephen B; Galloway, Susan M; Davis, George H; McNatty, Kenneth P

    2007-12-01

    Woodlands sheep have a putative genetic mutation (FecX2(W)) that increases ovulation rate. At present, the identity of FecX2(W) is unknown. The trait does not appear to be due to the previously described mutations in bone morphogenetic protein 15 (BMP15), growth differentiation factor 9 (GDF9), or bone morphogenetic protein receptor type 1B (BMPR1B) that affect ovulation rate in sheep. Potentially, FecX2(W) could be an unidentified genetic mutation in BMP15 or in the closely related GDF9, which interacts with BMP15 to control ovarian function. Alternatively, FecX2(W) may affect ovulation rate by changing the expression patterns in the molecular pathways activated by genes known to regulate ovulation rate. The objectives of these experiments were to sequence the complete coding region of the BMP15 and GDF9 genes, determine the patterns of expression of mRNAs encoding GDF9, BMP15, TGFBR1, BMPR1B, and BMPR2 during follicular development, and characterize the follicular populations in ewes heterozygous for the Woodlands mutation and their wild-type contemporaries. No differences in the coding sequences of BMP15 or GDF9 genes were identified that were associated with enhanced ovulation rate. The expression patterns of GDF9 and BMPR2 mRNAs were not different between genotypes. However, expression of BMP15 mRNA was less in oocytes of FecX2(W) ewes in large preantral and antral follicles. Expression of ALK5 mRNA was significantly higher in the oocytes of FecX2(W) ewes, whereas expression of BMPR1B was decreased in both oocytes and granulosa cells of FecX2(W) ewes. FecX2(W) ewes also had increased numbers of antral follicles <1 mm in diameter. These follicles were smaller in average diameter, with the oocytes also being of a smaller mean diameter. Given that a mutation in BMP15 or BMPR1B results in increased ovulation rates in sheep, the differences in expression levels of BMP15 and BMPR1B may play a role in the increase in ovulation rate observed in Woodlands ewes with the

  7. Collision Induced Dissociation of [4Fe-4S] Cubane Cluster Complexes: [Fe4S4C14-x(SC2H5)x]2-/1- (x=0-4)

    SciTech Connect

    Fu, Youjun; Laskin, Julia; Wang, Lai S.

    2006-09-01

    Collision-induced dissociation (CID) experiments on a series of [4Fe-4S] cluster ions, [Fe4S4Cl4-x(SC2H5)x]2-/1- (x = 0 - 4), revealed that their fragmentation channels change with the coordination environment. Among the three Coulomb repulsion related channels for the doubly charged species, the collision induced electron detachment channel was found to become more significant from x = 0 to 4 due to the decreasing electron binding energies and the magnitude of the repulsion Coulomb barrier, while both the ligand detachment of Cl- and the fission of the [Fe4S4]2+ core became more and more significant with the increase of the Cl- coordination, and eventually became the dominant channel at x = 0. From the parents containing the -SC2H5 ligand, neutral losses of HSC2H5 (62) and/or HSCH=CH2 (60) were observed. It was proposed that inter- and intra-ligand proton transfer could happen during the CID process, resulting in hydrogen coordination to the [4Fe-4S] cluster. In the presence of O2, [Fe4S4Cl3(SC2H5)]2- and [Fe4S4Cl4]2- can form the O2-substituted products [Fe4S4Cl2(SC2H5)O2]- and [Fe4S4Cl3O2]-, respectively. It was shown that the O2 complexation occurs by coordination to the empty iron site of the [4Fe-4S] cubane core after dissociation of one Cl- ligand.

  8. Relations between X-ray emissions, magnetic fields and electric currents during the X2.2 flare on the 15 February 2011

    NASA Astrophysics Data System (ADS)

    Musset, Sophie; Vilmer, Nicole; Bommier, Véronique

    2014-05-01

    The energy released during solar flares is believed to be stored in non-potential magnetic fields associated with electric currents. The aim of this paper is to study the relation between the location of the X-ray emissions produced by energetic electrons accelerated in the corona, the magnetic fields and the vertical current densities from measurements in the photosphere, during the X2.2 flare on the 15 February 2011 (AR NOAA 11158). We created X-ray images with the data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) to overlay them on magnetic field maps and current density maps calculated with the UNNOFIT inversion and Metcalf disambiguation codes from the spectropolarimetric measurements of the Helioseismic and Magnetic Imager (HMI) on the Solar Dynamics Observatory (SDO). We conclude that the X-rays emitted by thermal and non-thermal electrons during the flare are located above or very close to the photospheric current sheet. A comparison between X-ray and Extreme Ultraviolet (EUV) images from the SDO Atmospheric Imaging Assembly (AIA) and a spectral analysis of the X-ray emission complete the study of the flare.

  9. Adsorption site and structure determination of c(2x2) N{sub 2}/Ni(100) using angle-resolved photoemission extended fine structure

    SciTech Connect

    Moler, E.J.; Kellar, S.A.; Huff, W.R.A.

    1997-04-01

    The authors have determined the atomic spatial structure of c(2x2) N2Ni(100) with Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) from the nitrogen 1s core level using monochromatized x-rays from beamline 6.1 at SSRL and beamline 9.3.2 at the ALS. The chemically shifted N 1s peak intensities were summed together to obtain ARPEFS curves for both nitrogen atoms in the molecule. They used a new, highly-optimized program based on the Rehr-Albers scattering matrix formalism to find the adsorption site and to quantitatively determine the bond-lengths. The nitrogen molecule stands upright at an atop site, with a N-Ni bond length of 2.25(1) {angstrom}, a N-N bond length of 1.10(7) {angstrom}, and a first layer Ni-Ni spacing of 1.76(4) {angstrom}. The shake-up peak shows an identical ARPEFS diffraction pattern, confirming its intrinsic nature and supporting a previous use of this feature to decompose the peak into contributions from the chemically inequivalent nitrogen atoms. Comparison to a previously published theoretical treatment of N-N-Ni and experimental structures of analogous adsorbate systems demonstrates the importance of adsorbate-adsorbate interactions in weakly chemisorbed systems.

  10. Helical Majorana fermions in d(x2-y2) + id(xy)-wave topological superconductivity of doped correlated quantum spin Hall insulators.

    PubMed

    Sun, Shih-Jye; Chung, Chung-Hou; Chang, Yung-Yeh; Tsai, Wei-Feng; Zhang, Fu-Chun

    2016-04-11

    There has been growing interest in searching for exotic self-conjugate, charge-neutral low-energy fermionic quasi-particles, known as Majorana fermions (MFs) in solid state systems. Their signatures have been proposed and potentially observed at edges of topological superconcuctors with non-trivial topological invariant in the bulk electronic band structure. Much effort have been focused on realizing MFs in odd-parity superconductors made of strong spin-orbit coupled materials in proximity to conventional superconductors. In this paper, we propose a novel mechanism for realizing MFs in 2D spin-singlet topological superconducting state induced by doping a correlated quantum spin Hall (Kane-Mele) insulator. Via a renormalized mean-field approach, the system is found to exhibits time-reversal symmetry (TRS) breaking d(x2-y2) + id(xy)-wave (chiral d-wave) superconductivity near half-filling in the limit of large on-site repulsion. Surprisingly, however, at large spin-orbit coupling, the system undergoes a topological phase transition and enter into a new topological phase protected by a pseudo-spin Chern number, which can be viewed as a persistent extension of the quantum spin Hall phase upon doping. From bulk-edge correspondence, this phase is featured by the presence of two pairs of counter-propagating helical Majorana modes per edge, instead of two chiral propagating edge modes in the d + id' superconductors.

  11. Effect of temperature on the distribution and inhomogeneity degree of Se-S atoms in CuIn(Se1-x S x )2 alloys

    NASA Astrophysics Data System (ADS)

    Xue, Hong-Tao; Tang, Fu-Ling; Zhang, Fu-Zhen; Lu, Wen-Jiang; Feng, Yu-Dong

    2016-01-01

    The distribution morphologies and inhomogeneity degrees of Se-S atoms in CuIn(Se1-x S x )2 (CISS) alloys with seven concentrations of sulphur atoms were studied at the temperature range from 23 K to 973 K using Monte Carlo simulations based on the cluster expansion method and first-principles calculations. We found the S(Se) atoms in CISS alloys cluster in a form of ellipsoid or lamella at low temperatures as the concentration of S atoms changes. And the Se-S distribution in CISS alloys becomes more and more homogeneous as the temperature increases. A sharp decline in the inhomogeneity degree σ within a certain temperature range for CISS alloys indicates a phase transition from an inhomogeneous state to a homogeneous state is occurring. And the homogeneous state here is not a totally homogeneous state due to the unavoidable inhomogeneity of CISS alloys. The relation between the inhomogeneity degree and temperature follows well the Boltzmann function model. Finally, a reliable method for predicting the phase transition temperature of similar alloys was proposed.

  12. Evaluation of uranium geochemical anomalies in the Spartanburg 1/sup 0/ x 2/sup 0/ NTMS area near Pacolet Mills, SC

    SciTech Connect

    Owen, J.

    1981-06-01

    The Savannah River Laboratory (SRL) was involved in the National Uranium Resource Evaluation (NURE) program from 1974 through 1981. The SRL role was to design, conduct, and report the data from a geochemical reconnaissance of almost half the continental United States. The purpose of this work was to provide a basis for evaluating the uranium potential of areas and to identify areas meriting conventional geological followup. In this program over 275,000 samples of stream sediment, soil vegetation, and ground or surface water were collected. As a part of the development program to support interpretation of the geochemical data, SRL conducted a series of anomaly verification field studies. Each study area was chosen on the basis of a geochemical anomaly in reconnaissance data. Subcontractors were selected to conduct field scintillometer surveys, compile geologic maps, collect additional samples, or provide other services as deemed appropriate for a given study. This report, which summarizes the results of a study in the Spartanburg 1/sup 0/ x 2/sup 0/ quadrangle, was compiled for SRL by Jerry Owen and is published as a facsimile of this report to SRL. Normal editing was not done so that the report could be placed in the public domain prior to the termination of the NURE program. This study is one of a series designed to provide a basis for interpretation of SRL regional geochemical reconnaissance data. It contains a synthesis of published data and results of a four-channel gamma spectrometer survey of an area near Pacolet Mills, South Carolina.

  13. Evaluation of uranium geochemical anomalies in the Greenville 1/sup 0/ x 2/sup 0/ Quadrangle (Avalon, Greer, Honea, and Northeast Greenville). National Uranium Resource Evaluation program

    SciTech Connect

    Sargent, K. A.; Price, V. Jr.

    1982-08-01

    The Savannah River Laboratory (SRL) was involved in the National Uranium Resource Evaluation (NURE) from 1974 through 1981. The SRL role was to design, conduct, and report the data from a geochemical reconnaissance of almost half the continental United States. The purpose of this work was to provide a basis for evaluating the uranium potential of areas and to identify areas meriting conventional geologic followup. More than 275,000 samples of stream sediment, soil, vegetation, and ground or surface water were collected in the program. As a part of the development program to support interpretation of the geochemical data, SRL conducted a series of field studies to verify anomalies that were identified from reconnaissance data. Subcontractors were selected to conduct field scintillometer surveys, compile geologic maps, collect additional samples, or provide other services needed for a given study. This report summarizes the results of four small studies that were conducted for SRL by V.S. Griffin, Jr., in the Greenville 1/sup 0/ x 2/sup 0/ quadrangle. Normal editing was not done so the report could be released to the public before the termination of the NURE program. Thus, conceptual errors that may be present have not been corrected, and the reader is cautioned to use professional judgment in interpreting the data. These studies include original geologic maps and the results of field radioactivity measurements. 20 figures, 5 tables.

  14. Order-disorder phase transitions in the two-dimensional semiconducting transition metal dichalcogenide alloys Mo1−xWxX2 (X = S, Se, and Te)

    PubMed Central

    Gan, Li-Yong; Zhang, Qingyun; Zhao, Yu-Jun; Cheng, Yingchun; Schwingenschlögl, Udo

    2014-01-01

    A combination of density functional theory, an empirical model, and Monte Carlo simulations is used to shed light on the evolution of the atomic distribution in the two-dimensional semiconducting transition metal dichalcogenide alloys Mo1−xWxX2 (X = S, Se, and Te) as a function of the W concentration and temperature. Both random and ordered phases are discovered and the origin of the phase transitions is clarified. While the empirical model predicts at x = 1/3 and 2/3 ordered alloys, Monte Carlo simulations suggest that they only exist at low temperature due to a small energetic preference of Mo-X-W over Mo-X-Mo and W-X-W interactions, explaining the experimental observation of random alloy Mo1−xWxS2. Negative formation energies point to a high miscibility. Tunability of the band edges and band gaps by alteration of the W concentration gives rise to a broad range of applications. PMID:25331363

  15. Mechanical strain dependent electronic and dielectric properties of two-dimensional honeycomb structures of MoX2 (X=S, Se, Te)

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Ahluwalia, P. K.

    2013-06-01

    Mechanical strain induced tunability in two-dimensional (2D) honeycomb structures of MoX2 (X=S, Se, Te) with a focus on dielectric properties have been investigated in the framework of density functional theory. Mechanical strains reduce the band gap of considered semiconductors by causing a direct-to-indirect band gap transitions and finally rendering them into metal at critical value depending on the types of applied strain. The ultimate tensile strength estimated for MoS2, MoSe2 and MoTe2 monolayers is ∼7 GPa, ∼6 GPa and ∼5 GPa respectively. Band-gap deformation potentials have been found to posses strong dependence on the types of applied strain. Small tensile strains increases the exciton binding energies which can have importance in the applications of optoelectronics. Dielectric properties too get influenced by the type of applied strain as well as the type of material. Imaginary part of dielectric function (ɛ2) shows redshift in the structure peak energy on the application of strains with significant dependence on the types of applied strain. Static dielectric constant (ɛs) has been found to increase with the increase of tensile strains (both uniaxial and biaxial) and asymmetric biaxial strain. On the other hand, ɛs decreases for smaller magnitude of compression strains and show increase at higher magnitude. The change in the magnitude of ɛs particularly for compression strains remain material specific.

  16. Effects of Sb Content (x) on (Bi(1-x)Sb(x))2Te3 Thermoelectric Thin Film Deposited by Effusion Cell Evaporator.

    PubMed

    Yong, Ho; Na, Sekwon; Gang, Jun-Gu; Jeon, Seong-Jae; Hyun, Seungmin; Lee, Hoo-Jeong

    2015-10-01

    This paper investigates the effects of the Sb content (x) on (Bi(1-x)Sb(x))2Te3 thermoelectric films with x changing widely from 0 (Sb2Te3) to 1 (Bi2Te3). First, the XRD analysis discloses that with the Sb content (x) increasing, the phase changed gradually from Bi2Te3 to Sb2Te3 as Sb atoms replaced substitutionally Bi atoms. Further microstructure analysis reveals that an extensive grain growth occurred during post-annealing for the samples with high Sb contents. According to the measurement of electrical and thermoelectric properties, the polarity of the charge carrier and Seebeck coefficient switched n-type to p-type in the range of x = 0.45~0.63. For the n-type samples, the power factor is highest when x = 0.18 around 46.01 μW/K(2) whereas Sb2Te3, for the p-type samples, shows the highest value, 62.48 μW/K(2)cm.

  17. Effects of Sb Content (x) on (Bi(1-x)Sb(x))2Te3 Thermoelectric Thin Film Deposited by Effusion Cell Evaporator.

    PubMed

    Yong, Ho; Na, Sekwon; Gang, Jun-Gu; Jeon, Seong-Jae; Hyun, Seungmin; Lee, Hoo-Jeong

    2015-10-01

    This paper investigates the effects of the Sb content (x) on (Bi(1-x)Sb(x))2Te3 thermoelectric films with x changing widely from 0 (Sb2Te3) to 1 (Bi2Te3). First, the XRD analysis discloses that with the Sb content (x) increasing, the phase changed gradually from Bi2Te3 to Sb2Te3 as Sb atoms replaced substitutionally Bi atoms. Further microstructure analysis reveals that an extensive grain growth occurred during post-annealing for the samples with high Sb contents. According to the measurement of electrical and thermoelectric properties, the polarity of the charge carrier and Seebeck coefficient switched n-type to p-type in the range of x = 0.45~0.63. For the n-type samples, the power factor is highest when x = 0.18 around 46.01 μW/K(2) whereas Sb2Te3, for the p-type samples, shows the highest value, 62.48 μW/K(2)cm. PMID:26726497

  18. Electronic and magnetic properties of X2YZ and XYZ Heusler compounds: a comparative study of density functional theory with different exchange-correlation potentials

    NASA Astrophysics Data System (ADS)

    Rai, D. P.; Sandeep; Shankar, A.; Pradhan Sakhya, Anup; Sinha, T. P.; Khenata, R.; Ghimire, M. P.; Thapa, R. K.

    2016-07-01

    The electronic and magnetic properties of Heusler compounds X2YZ and XYZ (X = Co, Ni, Pt, Fe; Y = Mn, Cr, Vi; Z = Al, Sb, Ga) are investigated by using the density functional theory with generalized gradient approximation (GGA), GGA plus U (LSDA+U), and modified Becke-Johnson (mBJ) exchange potential. It is found that the half-metallic gaps are generally widened reasonably by LSDA+U and mBJ as compared to the conventional GGA. For the Co-based Heusler compounds the inclusion of U in GGA leads to a larger minority band gap while it is destroyed for Fe2VAl and NiMnSb. The magnetic properties of Co2VSi and Co2VSn are well defined within LSDA+U and mBJ with an exact integer value of magnetic moment. The band gaps of Fe2VAl and CoMnSb given by mBJ are in good agreement with the available experimental data of x-ray absorption spectroscopy. Except for the reasonably larger band gap, the mBJ band structure is almost same as that of GGA but is remarkably different from that of LSDA+U.

  19. Topochemical Transformations of CaX2 (X=C, Si, Ge) to Form Free-Standing Two-Dimensional Materials.

    PubMed

    Pratik, Saied Md; Nijamudheen, A; Datta, Ayan

    2015-12-01

    Topochemical transformations of layered materials CaX2 (X=Si, Ge) are the method of choice for the high-yield synthesis of pristine, defect-free two-dimensional systems silicane and germanane, which have advanced electronic properties. Based on solid-state dispersion-corrected calculations, mechanisms for such transformations are elucidated that provide an in-depth understanding of phase transition in these layered materials. While formation of such layered materials is highly favorable for silicane and germanane, a barrier of 1.2 eV in the case of graphane precludes its synthesis from CaC2 topochemically. The energy penalty required for distorting linear acetylene into a trans-bent geometry accounts for this barrier. In contrast it is highly favorable in the heavier analogues, resulting in barrierless topochemical generation of silicane and germanane. Photochemical generation of the trans-bent structure of acetylene in its first excited state (S1 ) can directly generate graphane through a barrierless condensation. Unlike the buckled structure of silicene, the phase-h of CaSi2 with perfectly planar silicene layers exhibits the Dirac cones at the high symmetry points K and H. Interestingly, topochemical acidification of the cubic phase of calcium carbide is predicted to generate the previously elusive platonic hydrocarbon, tetrahedrane.

  20. Genomic analysis of a 1 Mb region near the telomere of Hessian fly chromosome X2 and avirulence gene vH13

    PubMed Central

    Lobo, Neil F; Behura, Susanta K; Aggarwal, Rajat; Chen, Ming-Shun; Collins, Frank H; Stuart, Jeff J

    2006-01-01

    Background To have an insight into the Mayetiola destructor (Hessian fly) genome, we performed an in silico comparative genomic analysis utilizing genetic mapping, genomic sequence and EST sequence data along with data available from public databases. Results Chromosome walking and FISH were utilized to identify a contig of 50 BAC clones near the telomere of the short arm of Hessian fly chromosome X2 and near the avirulence gene vH13. These clones enabled us to correlate physical and genetic distance in this region of the Hessian fly genome. Sequence data from these BAC ends encompassing a 760 kb region, and a fully sequenced and assembled 42.6 kb BAC clone, was utilized to perform a comparative genomic study. In silico gene prediction combined with BLAST analyses was used to determine putative orthology to the sequenced dipteran genomes of the fruit fly, Drosophila melanogaster, and the malaria mosquito, Anopheles gambiae, and to infer evolutionary relationships. Conclusion This initial effort enables us to advance our understanding of the structure, composition and evolution of the genome of this important agricultural pest and is an invaluable tool for a whole genome sequencing effort. PMID:16412254

  1. Helical Majorana fermions in d(x2-y2) + id(xy)-wave topological superconductivity of doped correlated quantum spin Hall insulators.

    PubMed

    Sun, Shih-Jye; Chung, Chung-Hou; Chang, Yung-Yeh; Tsai, Wei-Feng; Zhang, Fu-Chun

    2016-01-01

    There has been growing interest in searching for exotic self-conjugate, charge-neutral low-energy fermionic quasi-particles, known as Majorana fermions (MFs) in solid state systems. Their signatures have been proposed and potentially observed at edges of topological superconcuctors with non-trivial topological invariant in the bulk electronic band structure. Much effort have been focused on realizing MFs in odd-parity superconductors made of strong spin-orbit coupled materials in proximity to conventional superconductors. In this paper, we propose a novel mechanism for realizing MFs in 2D spin-singlet topological superconducting state induced by doping a correlated quantum spin Hall (Kane-Mele) insulator. Via a renormalized mean-field approach, the system is found to exhibits time-reversal symmetry (TRS) breaking d(x2-y2) + id(xy)-wave (chiral d-wave) superconductivity near half-filling in the limit of large on-site repulsion. Surprisingly, however, at large spin-orbit coupling, the system undergoes a topological phase transition and enter into a new topological phase protected by a pseudo-spin Chern number, which can be viewed as a persistent extension of the quantum spin Hall phase upon doping. From bulk-edge correspondence, this phase is featured by the presence of two pairs of counter-propagating helical Majorana modes per edge, instead of two chiral propagating edge modes in the d + id' superconductors. PMID:27064108

  2. A discharge flow-photoionization mass spectrometric study of the FO(X 2 Pi i) radical. Photoionization efficiency spectrum and ionization energy

    NASA Technical Reports Server (NTRS)

    Zhang, Zhengyu; Kuo, Szu-Cherng; Klemm, R. Bruce; Monks, Paul S.; Stief, Louis J.

    1994-01-01

    Photoionization efficiency spectra of FO were measured over the wavelength range 80.0-100.0 nm and in the ionization threshold region, 94.0-100.0 nm, using a discharge flow-photoionization mass spectrometer apparatus coupled to a synchrotron radiation source. FO was generated by the reaction of F2P atoms with NO3 and via a F2O2 discharge. A value of 12.78 +/- 0.03 eV was obtained for the adiabatic ionization energy of FO from photoion thresholds which corresponds to FO(+)(X 3 Sigma -) from FO(X 2 Pi i). These results, which are the first to be obtained by direct Photo-ionization mass spectrometry (PIMS) measurements, corroborate those of a photoelectron spectroscopy (PES) study; however, the ionization energy determined here is free from interferences due to other species which complicated the PES measurement. A value of 109.5 +/- 8.0 kJ/mol for Delta f H 0 298(FO) is computed from the present value of IE(FO) and a previous appearance energy measurement, and a value for the proton affinity of FO is calculated to be 511.5 +/- 10.0 kJ/mol.

  3. Amplitude modulation drive to rectangular-plate linear ultrasonic motors with vibrators dimensions 8 mm x 2.16 mm X 1 mm.

    PubMed

    Ming, Yang; Hanson, Ben; Levesley, Martin C; Walker, Peter G; Watterson, Kevin G

    2006-12-01

    In this paper, to exploit the contribution from not only the stators but also from other parts of miniature ultrasonic motors, an amplitude modulation drive is proposed to drive a miniature linear ultrasonic motor consisting of two rectangular piezoelectric ceramic plates. Using finite-element software, the first longitudinal and second lateral-bending frequencies of the vibrator are shown to be very close when its dimensions are 8 mm x 2.16 mm x 1 mm. So one single frequency power should be able to drive the motor. However, in practice the motor is found to be hard to move with a single frequency power because of its small vibration amplitudes and big frequency difference between its longitudinal and bending resonance, which is induced by the boundary condition variation. To drive the motor effectively, an amplitude modulation drive is used by superimposing two signals with nearly the same frequencies, around the resonant frequency of the vibrators of the linear motor. When the amplitude modulation frequency is close to the resonant frequency of the vibrator's surroundings, experimental results show that the linear motor can move back and forward with a maximum thrust force (over 0.016 N) and a maximum velocity (over 50 mm/s).

  4. Electronic and magnetic properties of X2YZ and XYZ Heusler compounds: a comparative study of density functional theory with different exchange-correlation potentials

    NASA Astrophysics Data System (ADS)

    Rai, D. P.; Sandeep; Shankar, A.; Pradhan Sakhya, Anup; Sinha, T. P.; Khenata, R.; Ghimire, M. P.; Thapa, R. K.

    2016-07-01

    The electronic and magnetic properties of Heusler compounds X2YZ and XYZ (X = Co, Ni, Pt, Fe; Y = Mn, Cr, Vi; Z = Al, Sb, Ga) are investigated by using the density functional theory with generalized gradient approximation (GGA), GGA plus U (LSDA+U), and modified Becke‑Johnson (mBJ) exchange potential. It is found that the half-metallic gaps are generally widened reasonably by LSDA+U and mBJ as compared to the conventional GGA. For the Co-based Heusler compounds the inclusion of U in GGA leads to a larger minority band gap while it is destroyed for Fe2VAl and NiMnSb. The magnetic properties of Co2VSi and Co2VSn are well defined within LSDA+U and mBJ with an exact integer value of magnetic moment. The band gaps of Fe2VAl and CoMnSb given by mBJ are in good agreement with the available experimental data of x-ray absorption spectroscopy. Except for the reasonably larger band gap, the mBJ band structure is almost same as that of GGA but is remarkably different from that of LSDA+U.

  5. Evolution of magnetic layers stacking sequence within the magnetic structure of Ho(CoxNi1-x)2B2C

    NASA Astrophysics Data System (ADS)

    ElMassalami, M.; Takeya, H.; Ouladdiaf, B.; Gomes, A. M.; Paiva, T.; dos Santos, R. R.

    2014-12-01

    We evaluated the influence of Co substitution on the magnetic structure of Ho(CoxNi1-x)2B2C (x=0.2, 0.4, 0.6, 0.8) using neutron diffraction, magnetization and specific heat studies. Different modes are stabilized: an AFM k=(0,0,1) mode for x=0.2, a spiral k=(0,0,0.49) mode for x=0.4, a spiral k=(0,0,0.26) mode for x=0.6, and a FM k=(0,0,0) mode for x=0.8. Recalling that for x=0.0, k=(0,0,1) while for x=1.0, k=(0,0,0), then all these magnetic structures can be visualized as a variation in the stacking sequence, along the z-axis, of the intra-planar FM-coupled Ho sheets as such Co substitution controls the z-component of the k=(0,0,ux) vector where ux=0,0.26,0.49, or 1. We discuss this inference and the observation that in spite of such a diversity of magnetic structures, the critical temperatures and the saturated moments are only weakly influenced by substitution.

  6. Spatial digital database for the geologic map of the east part of the Pullman 1° x 2° quadrangle, Idaho

    USGS Publications Warehouse

    Rember, William C.; Bennett, Earl H.

    2001-01-01

    he paper geologic map of the east part of the Pullman 1·x 2· degree quadrangle, Idaho (Rember and Bennett, 1979) was scanned and initially attributed by Optronics Specialty Co., Inc. (Northridge, CA) and remitted to the U.S. Geological Survey for further attribution and publication of the geospatial digital files. The resulting digital geologic map GIS can be queried in many ways to produce a variety of geologic maps. This digital geospatial database is one of many being created by the U.S. Geological Survey as an ongoing effort to provide geologic information in a geographic information system (GIS) for use in spatial analysis. Digital base map data files (topography, roads, towns, rivers and lakes, and others.) are not included: they may be obtained from a variety of commercial and government sources. This database is not meant to be used or displayed at any scale larger than 1:250,000 (for example, 1:100,000 or 1:24,000). The digital geologic map graphics and plot files (pull250k.gra/.hp /.eps) that are provided in the digital package are representations of the digital database.

  7. The Nicotinic α6 Subunit Gene Determines Variability in Chronic Pain Sensitivity via Cross-inhibition of P2X2/3 Receptors

    PubMed Central

    Wieskopf, Jeffrey S.; Mathur, Jayanti; Limapichat, Walrati; Post, Michael R.; Al-Qazzaz, Mona; Sorge, Robert E.; Martin, Loren J.; Zaykin, Dmitri V.; Smith, Shad B.; Freitas, Kelen; Austin, Jean-Sebastien; Dai, Feng; Zhang, Jie; Marcovitz, Jaclyn; Tuttle, Alexander H.; Slepian, Peter M.; Clarke, Sarah; Drenan, Ryan M.; Janes, Jeff; Sharari, Shakir Al; Segall, Samantha K.; Aasvang, Eske K.; Lai, Weike; Bittner, Reinhard; Richards, Christopher I.; Slade, Gary D.; Kehlet, Henrik; Walker, John; Maskos, Uwe; Changeux, Jean-Pierre; Devor, Marshall; Maixner, William; Diatchenko, Luda; Belfer, Inna; Dougherty, Dennis A.; Su, Andrew I.; Lummis, Sarah C.R.; Damaj, M. Imad; Lester, Henry A.; Patapoutian, Ardem; Mogil, Jeffrey S.

    2016-01-01

    Chronic pain is a highly prevalent and poorly managed human health problem. We used microarray-based expression genomics in 25 inbred mouse strains to identify dorsal root ganglion (DRG)-expressed genetic contributors to mechanical allodynia, a prominent symptom of chronic pain. We identified expression levels of Chrna6, which encodes the α6 subunit of the nicotinic acetylcholine receptor (nAChR), as highly associated with allodynia. We confirmed the importance of α6* (i.e., α6-containing) nAChRs by analyzing both gain- and loss-of-function mutants. We find that mechanical allodynia associated with neuropathic and inflammatory injuries is significantly altered in α6* mutants, and that α6* but not α4* nicotinic receptors are absolutely required for peripheral and/or spinal nicotine analgesia. Furthermore, we show that Chrna6’s role in analgesia is at least partially due to direct interaction and cross-inhibition of α6* nAChRs with P2X2/3 receptors in DRG nociceptors. Finally, we establish relevance of our results to humans by the observation of genetic association in patients suffering from chronic postsurgical pain and temporomandibular pain. PMID:25972004

  8. Underlying theory of a model for the Renner-Teller effect in tetra-atomic molecules: X(2)Πu electronic state of C2H2(+).

    PubMed

    Perić, M; Jerosimić, S; Mitić, M; Milovanović, M; Ranković, R

    2015-05-01

    In the present study, we prove the plausibility of a simple model for the Renner-Teller effect in tetra-atomic molecules with linear equilibrium geometry by ab initio calculations of the electronic energy surfaces and non-adiabatic matrix elements for the X(2)Πu state of C2H2 (+). This phenomenon is considered as a combination of the usual Renner-Teller effect, appearing in triatomic species, and a kind of the Jahn-Teller effect, similar to the original one arising in highly symmetric molecules. Only four parameters (plus the spin-orbit constant, if the spin effects are taken into account), which can be extracted from ab initio calculations carried out at five appropriate (planar) molecular geometries, are sufficient for building up the Hamiltonian matrix whose diagonalization results in the complete low-energy (bending) vibronic spectrum. The main result of the present study is the proof that the diabatization scheme, hidden beneath the apparent simplicity of the model, can safely be carried out, at small-amplitude bending vibrations, without cumbersome computation of non-adiabatic matrix elements at large number of molecular geometries.

  9. Doping dependence and electron-boson coupling in the ultrafast relaxation of hot electron populations in Ba(Fe1-x Co x )2As2

    NASA Astrophysics Data System (ADS)

    Avigo, I.; Thirupathaiah, S.; Ligges, M.; Wolf, T.; Fink, J.; Bovensiepen, U.

    2016-09-01

    Using femtosecond time- and angle-resolved photoemission spectroscopy we investigate the effect of electron doping on the electron dynamics in {Ba}{({{Fe}}1-x{{Co}}x)}2{{As}}2 in a range of 0≤slant x\\lt 0.15 at temperatures slightly above the Néel temperature. By analyzing the time-dependent photoemission intensity of the pump laser excited population as a function of energy, we found that the relaxation times at 0\\lt E-{E}{{F}}\\lt 0.2 {eV} are doping dependent and about 100 fs shorter at optimal doping than for overdoped and parent compounds. Analysis of the relaxation rates also reveals the presence of a pump fluence dependent step in the relaxation time at E-{E}{{F}}=200 {meV} which we explain by coupling of the excited electronic system to a boson of this energy. We compare our results with static ARPES and transport measurements and find disagreement and agreement concerning the doping-dependence, respectively. We discuss the effect of the electron-boson coupling on the energy-dependent relaxation and assign the origin of the boson to a magnetic excitation.

  10. Phase transformations induced by high electronic excitation in ion-irradiated Gd2(ZrxTi1-x)2O7 pyrochlores

    NASA Astrophysics Data System (ADS)

    Sattonnay, G.; Moll, S.; Thomé, L.; Decorse, C.; Legros, C.; Simon, P.; Jagielski, J.; Jozwik, I.; Monnet, I.

    2010-11-01

    The pyrochlore oxides (A2B2O7) exhibit a remarkable range of structural, physical, and magnetic properties related to their various chemical compositions. This article reports the phase transformations induced by high electronic excitation in pyrochlores of the Gd2(ZrxTi1-x)2O7 family irradiated with swift ions. The structural changes, investigated by using several analytical techniques (x-ray diffraction, Raman spectroscopy, and transmission electron microscopy), strongly depend on the chemical composition. The high electronic excitation along the ion trajectory results in the amorphization of ion tracks for Gd2Ti2O7 and Gd2TiZrO7, whereas a defective fluorite structure is formed in Gd2Zr2O7. Moreover, the results underline the existence of an electronic stopping power threshold of 6 keV/nm for amorphizable compounds and 10 keV/nm for Gd2Zr2O7, below which phase transformations do not occur. Finally, the study of the thermal recovery of irradiated pyrochlores provides the recrystallization temperature for amorphized samples and reveals differences in the recovery process which are related to the chemical composition.

  11. Role of dimensionality in the Kondo Ce T X2 family: The case of CeCd0.7Sb2

    NASA Astrophysics Data System (ADS)

    Rosa, P. F. S.; Bourg, R. J.; Jesus, C. B. R.; Pagliuso, P. G.; Fisk, Z.

    2015-10-01

    Motivated by the presence of competing magnetic interactions in the heavy fermion family Ce T X2 (T = transitionmetal, X =pnictogen), here we study the novel parent compound CeCd0.7Sb2 by combining magnetization, electrical resistivity, and heat-capacity measurements. Contrary to the antiferromagnetic (AFM) ground state observed in most members of this family, the magnetic properties of our CeCd0.7Sb2 single crystals revealed a ferromagnetic ordering at Tc=3 K with an unusual soft behavior. By using a mean field model including anisotropic nearest-neighbor interactions and the tetragonal crystalline electric field (CEF) Hamiltonian, a systematic analysis of our macroscopic data was obtained. Our fits allowed us to extract a simple but very distinct CEF scheme, as compared to the AFM counterparts. As in the previously studied ferromagnet CeAgSb2, a pure |±1 /2 > ground state is realized, hinting at a general trend within the ferromagnetic members. More generally, we propose a scenario for the understanding of the magnetism in this family of compounds based on the subtle changes of dimensionality in the crystal structure.

  12. Molecule-doped rare gas clusters: structure and stability of ArnNO(X2 Π potential energy surfaces of ArNO

    NASA Astrophysics Data System (ADS)

    Naumkin, F. Y.; Wales, D. J.

    High level ab initio calculations carried out for the 2A' and 2A'' states of ArNO(X2Π) predict a crossing near the T-shape configuration, with the 2A' minimum being slightly deeper. SΠn-orbit coupling is included through a model treatment and results in two potential energy surfaces with similar topologies, nearly parallel to each other and close to the averaged non-relativistic surface. These results are used to construct a DIM-like model for ArnNO clusters. The lowest energy cluster structures are found to resemble those for Arn+1 with NO lying in the surface. The set of major magic numbers (structures of pronounced stability) is also the same as for the Arn+1 clusters, and is emphasized further by the detachment of NO, which requires a larger energy than for detachment of a single Ar atom. The relations of the difference between the two dissociation energies and of the ArnNO(1/2 to 3/2) excitation energy to the magic numbers are discussed.

  13. First principles studies on the impact of point defects on the phase stability of (AlxCr1-x)2O3 solid solutions

    NASA Astrophysics Data System (ADS)

    Koller, C. M.; Koutná, N.; Ramm, J.; Kolozsvári, S.; Paulitsch, J.; Holec, D.; Mayrhofer, P. H.

    2016-02-01

    Density Functional Theory applying the generalised gradient approximation is used to study the phase stability of (AlxCr1-x)2O3 solid solutions in the context of physical vapour deposition (PVD). Our results show that the energy of formation for the hexagonal α phase is lower than for the metastable cubic γ and B1-like phases-independent of the Al content x. Even though this suggests higher stability of the α phase, its synthesis by physical vapour deposition is difficult for temperatures below 800 °C. Aluminium oxide and Al-rich oxides typically exhibit a multi-phased, cubic-dominated structure. Using a model system of (Al0.69Cr0.31)2O3 which experimentally yields larger fractions of the desired hexagonal α phase, we show that point defects strongly influence the energetic relationships. Since defects and in particular point defects, are unavoidably present in PVD coatings, they are important factors and can strongly influence the stability regions. We explicitly show that defects with low formation energies (e.g. metal Frenkel pairs) are strongly preferred in the cubic phases, hence a reasonable factor contributing to the observed thermodynamically anomalous phase composition.

  14. Ultrabroadband dielectric spectroscopy and phonons in (Pb1-x/2Lax)(Zr0.9Ti0.1)O3

    NASA Astrophysics Data System (ADS)

    Buixaderas, E.; Bovtun, V.; Veljko, S.; Savinov, M.; Kužel, P.; Gregora, I.; Kamba, S.; Reaney, I.

    2010-11-01

    The dielectric behavior of (Pb1-x/2Lax)(Zr0.9Ti0.1)O3 PLZT 100x/90/10 (0≤100x≤1) was studied in the frequency range 102-1014 Hz using dielectric, time-domain terahertz (THz), far-infrared, and Raman spectroscopy in the temperature interval 10-900 K. PZT 90/10 and PLZT 2/90/10 undergo two phase transitions, from a cubic paraelectric to a rhombohedral untilted ferroelectric (FE) phase and on further cooling to a tilted FE phase. PLZT 4/90/10 and PLZT 10/90/10 are incommensurately modulated and composed of an intergrowth of polar and antipolar cation displacements. These samples consequently demonstrate a FE soft mode which exhibits minimal frequency several tens of degrees above the nominal antiferroelectric phase transition temperature. The dielectric response of PLZT 100x/90/10 is mainly governed by a gigahertz relaxation and a soft phonon component in the THz range. As in other PbO-based perovskites, the soft mode is split into a higher-frequency component (ω ˜80 cm-1) and a highly damped THz component (ω ˜30 cm-1), with larger dielectric strength already in the paraelectric phase.

  15. Synthesis, spectral, X-ray single structure, DFT calculations and antimicrobial activities of [Co(II)X2 (dmphen)] (X = Br and SCN-)

    NASA Astrophysics Data System (ADS)

    Al-Noaimi, Mousa; Awwadi, Firas F.; Haddad, Salim F.; Talib, Wamidh H.; Jodeh, Shehdeh; Radi, Smaail; Ben Hadda, Taibi; Abdoh, Muneer; Naveen, S.; Lokanath, N. K.; Warad, Ismail

    2015-04-01

    Two tetrahedral mononuclear complexes with a general formula [CoX2(dmphen)](1-2) (where dmphen is 2,9-dimethyl-1,10-phenanthroline and 1 (X = Br), 2 (X = NCS)) have been synthesized. These complexes are characterized by elemental analysis, IR, UV-visible, TG/DTA and by X-ray diffraction. The calculated electrostatic potential surface of 2 has shown that the electrostatic potential values around sulfur atom is anistropically distributed; the potential values along C-S bond is less negative than the corresponding values in the π-region of S atom. This agrees with the observed geometrical arrangement of C-H⋯S-C hydrogen bonding interactions, the avg. of H⋯S-C angle is 81°. Antimicrobial properties of cobalt(II) complexes was also assessed. Cobalt complexes exhibited significant antibacterial activity against different gram negative and positive human pathogens. The absorption spectrum of these complexes in acetone was modeled by time-dependent density functional theory (TD-DFT).

  16. Molecular docking studies of (X-methylphenyl)-5-nitro-6-amino-3-pyridinecarboxmide (X=2,3,4,5,6) as potential inhibitors for Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    Premkumar, S.; Asath, R. Mohamed; Rekha, T. N.; Jawahar, A.; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-01

    An insilico and density functional theory (DFT) calculations were carried out for (X-methylphenyl)-5-nitro-6-amino-3-pyridinecarboxmide (X-MPNAPC),{X=2,3,4,5,6} to evaluate the potential inhibitors for Alzheimer's disease. The molecular structure of 2-MPNAPC, 3-MPNAPC, 4-MPNAPC, 5-MPNAPC and 6-MPNAPC molecules was optimized by the DFT/B3LYP method with cc-pVTZ basis set using the Gaussian 09 program. The inhibitory nature of the molecules against enzyme acetylcholinesterase (AChE) catalyzes was evaluated by molecular docking studies. The molecular docking parameters such as binding energy, inhibition constant and intermolecular energy were calculated by the AutoDock 4.0 software. The higher binding energy, intermolecular energy and lower inhibition constant values suggested that the 2-MPNAPC molecule has higher inhibitory nature against the AChE catalyzes, which confirm that the 2-MPNAPC molecule is a potential inhibitor for the Alzheimer's disease. The molecular reactivity was also studied by the frontier molecular orbitals analysis.

  17. MAGNETOHYDRODYNAMIC SIMULATION OF THE X2.2 SOLAR FLARE ON 2011 FEBRUARY 15. II. DYNAMICS CONNECTING THE SOLAR FLARE AND THE CORONAL MASS EJECTION

    SciTech Connect

    Inoue, S.; Magara, T.; Choe, G. S.; Hayashi, K.; Park, Y. D.

    2015-04-20

    We clarify a relationship between the dynamics of a solar flare and a growing coronal mass ejection (CME) by investigating the dynamics of magnetic fields during the X2.2-class flare taking place in the solar active region 11158 on 2011 February 15, based on simulation results obtained from Inoue et al. We found that the strongly twisted lines formed through tether-cutting reconnection in the twisted lines of a nonlinear force-free field can break the force balance within the magnetic field, resulting in their launch from the solar surface. We further discover that a large-scale flux tube is formed during the eruption as a result of the tether-cutting reconnection between the eruptive strongly twisted lines and these ambient weakly twisted lines. The newly formed large flux tube exceeds the critical height of the torus instability. Tether-cutting reconnection thus plays an important role in the triggering of a CME. Furthermore, we found that the tangential fields at the solar surface illustrate different phases in the formation of the flux tube and its ascending phase over the threshold of the torus instability. We will discuss these dynamics in detail.

  18. Search for the OH (X(2)Pi) Meinel band emission in meteors as a tracer of mineral water in comets: detection of N(2)(+) (A-X).

    PubMed

    Jenniskens, Peter; Laux, Christophe O

    2004-01-01

    We report the discovery of the N(2)(+) A-X Meinel band in the 780-840 nm meteor emission from two Leonid meteoroids that were ejected less than 1000 years ago by comet 55P/Tempel-Tuttle. Our analysis indicates that the N(2)(+) molecule is at least an order of magnitude less abundant than expected, possibly as a result of charge transfer reactions with meteoric metal atoms. This new band was found while searching for rovibrational transitions in the X(2)Pi electronic ground state of OH (the OH Meinel band), a potential tracer of water bound to minerals in cometary matter. The electronic A-X transition of OH has been identified in other Leonid meteors. We did not detect this OH Meinel band, which implies that the excited A state is not populated by thermal excitation but by a mechanism that directly produces OH in low vibrational levels of the excited A(2)Sigma state. Ultraviolet dissociation of atmospheric or meteoric water vapor is such a mechanism, as is the possible combustion of meteoric organics.

  19. Search for the OH (X(2)Pi) Meinel band emission in meteors as a tracer of mineral water in comets: detection of N(2)(+) (A-X)

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Laux, Christophe O.

    2004-01-01

    We report the discovery of the N(2)(+) A-X Meinel band in the 780-840 nm meteor emission from two Leonid meteoroids that were ejected less than 1000 years ago by comet 55P/Tempel-Tuttle. Our analysis indicates that the N(2)(+) molecule is at least an order of magnitude less abundant than expected, possibly as a result of charge transfer reactions with meteoric metal atoms. This new band was found while searching for rovibrational transitions in the X(2)Pi electronic ground state of OH (the OH Meinel band), a potential tracer of water bound to minerals in cometary matter. The electronic A-X transition of OH has been identified in other Leonid meteors. We did not detect this OH Meinel band, which implies that the excited A state is not populated by thermal excitation but by a mechanism that directly produces OH in low vibrational levels of the excited A(2)Sigma state. Ultraviolet dissociation of atmospheric or meteoric water vapor is such a mechanism, as is the possible combustion of meteoric organics.

  20. Effects of substitution, pressure, and temperature on the phonon mode in layered-rocksalt-type Li{sub (1−x)/2}Ga{sub (1−x)/2}Zn{sub x}O (x = 0.036–0.515) alloys

    SciTech Connect

    Tan, Lijie; Hu, Qiwei; Lei, Li Jiang, Xiaodong; Gao, Shangpan; He, Duanwei

    2015-11-14

    ZnO-based semiconductor alloys, Li{sub (1−x)/2}Ga{sub (1−x)/2}Zn{sub x}O (x = 0.036–0.515) with a layered-rocksalt-type structure, have been prepared under high pressure. The composition, pressure, and temperature dependence of phonons have been studied by Raman spectroscopy. We observe two disorder-activated Raman (DAR) modes when the Zn composition x increases: a broad Raman peak at ca. 400 cm{sup −1} and a left-shoulder peak at ca. 530 cm{sup −1} on the low-frequency side of A{sub 1g} mode at ca. 580 cm{sup −1}, which can be explained by reference to the phonon density of states for rocksalt-type ZnO. With the increase of the pressure and temperature, the left-shoulder DAR mode induced by substitution does not change at the same pace with the A{sub 1g} mode at Brillouin-zone center. We find that ion substitution can be seen as a kind of chemical pressure, and the chemical pressure caused by internal substitution and the physical pressure caused by external compression have equivalent effects on the shortening of correlation length, the distortion of crystal lattice, and the change of atomic occupation.

  1. Quercetin-induced benzophenanthridine alkaloid production in suspension cell cultures of Sanguinaria canadensis.

    PubMed

    Mahady, G B; Beecher, C W

    1994-12-01

    Addition of micromolar concentrations of quercetin or rutin to suspension cell cultures of Sanguinaria canadensis L. (bloodroot) induced the biosynthesis of sanguinarine and chelerythrine in a dose-dependent manner. In contrast, related compounds: baicalein, naringin, naringenin, catechin, caffeic acid and benzoic acid displayed very weak inductive activity. Of the two active flavonoids, quercetin was the most effective for inducing benzophenanthridine alkaloid biosynthesis, with doses of 100 microM increasing alkaloid production over 375% as compared to negative controls. Quercetin's inductive effects were similar to that of an elicitor derived from fungus Penicillium expansum (PE-elicitor). Suppression of quercetin and PE-induced alkaloid biosynthesis by low doses of actinomycin D (5 micrograms/ml, alpha-amanitin (20 micrograms/ml), or cycloheximide (1 microgram/ml) demonstrate a requirement for both RNA and de novo cytoplasmic protein synthesis and suggest that alterations in gene expression are involved in the inductive mechanism. Furthermore, quercetin-induced alkaloid biosynthesis was significantly reduced by pretreatment of the cells with the calcium chelator, EGTA (3 mM), or the calcium channel inhibitor, verapamil (100 microM), suggesting that this process was calcium dependent.

  2. Production of polypeptide antibiotic from Streptomyces parvulus and its antibacterial activity.

    PubMed

    Shetty, Prakasham Reddy; Buddana, Sudheer Kumar; Tatipamula, Vinay Bharadwaj; Naga, Yaswanth Varanasi Venkata; Ahmad, Jamal

    2014-01-01

    A highly potent secondary metabolite producing actinomycetes strain is isolated from marine soil sediments of Visakhapatnam sea coast, Bay of Bengal. Over all ten strains are isolated from the collected soil sediments. Among the ten actinomycetes strains the broad spectrum strain RSPSN2 was selected for molecular characterization, antibiotic production and its purification. The nucleotide sequence of the 1 rRNA gene (1261 base pairs) of the most potent strain evidenced a 96% similarity with Streptomyces parvulus 1044 strain, Streptomyces parvulus NBRC 13193 and Streptomyces parvulus BY-F. From the taxonomic features, the actinomycetes isolate RSPSN2 matches with Streptomyces parvulus in the morphological, physiological and biochemical characters. Thus, it was given the suggested name Streptomyces parvulus RSPSN2. The active metabolite was extracted using ethyl acetate (1:3, v/v) at pH 7.0. The separation of active ingredient and its purification was performed by using both thin layer chromatography (TLC) and column chromatography (CC) techniques. Spectrometric studies such as UV-visible, FTIR, and NMR and mass were performed. The antibacterial activity of pure compound was performed by cup plate method against some pathogenic bacteria including of streptomycin resistant bacteria like (Pseudomonas mirabilis, Pseudomonas putida and Bacillus cereus). In conclusion, the collected data emphasized the fact that a polypeptide antibiotic (Actinomycin D) was produced by Streptomyces parvulus RSPSN2.

  3. Production of polypeptide antibiotic from Streptomyces parvulus and its antibacterial activity

    PubMed Central

    Shetty, Prakasham Reddy; Buddana, Sudheer Kumar; Tatipamula, Vinay Bharadwaj; Naga, Yaswanth Varanasi Venkata; Ahmad, Jamal

    2014-01-01

    A highly potent secondary metabolite producing actinomycetes strain is isolated from marine soil sediments of Visakhapatnam sea coast, Bay of Bengal. Over all ten strains are isolated from the collected soil sediments. Among the ten actinomycetes strains the broad spectrum strain RSPSN2 was selected for molecular characterization, antibiotic production and its purification. The nucleotide sequence of the 1 rRNA gene (1261 base pairs) of the most potent strain evidenced a 96% similarity with Streptomyces parvulus 1044 strain, Streptomyces parvulus NBRC 13193 and Streptomyces parvulus BY-F. From the taxonomic features, the actinomycetes isolate RSPSN2 matches with Streptomyces parvulus in the morphological, physiological and biochemical characters. Thus, it was given the suggested name Streptomyces parvulus RSPSN2. The active metabolite was extracted using ethyl acetate (1:3, v/v) at pH 7.0. The separation of active ingredient and its purification was performed by using both thin layer chromatography (TLC) and column chromatography (CC) techniques. Spectrometric studies such as UV-visible, FTIR, and NMR and mass were performed. The antibacterial activity of pure compound was performed by cup plate method against some pathogenic bacteria including of streptomycin resistant bacteria like (Pseudomonas mirabilis, Pseudomonas putida and Bacillus cereus). In conclusion, the collected data emphasized the fact that a polypeptide antibiotic (Actinomycin D) was produced by Streptomyces parvulus RSPSN2. PMID:24948949

  4. The Conterminous United States Mineral Appraisal Program; background information to accompany folio of geologic, geochemical, geophysical, and mineral resource maps of the Choteau 1 degree x 2 degrees Quadrangle, Montana

    USGS Publications Warehouse

    Earhart, Robert L.; Grimes, David J.; Leinz, Reinhard W.; Kleinkopf, M. Dean

    1981-01-01

    The Choteau l? x 2? quadrangle in northwest Montana was studied by an interdisciplinary research team in order to appraise its mineral resource and hydrocarbon potential The appraisal is based on field and laboratory investigations of the geology, geochemistry, and geophysics. The results of the investigations are published as a folio of maps, figures, tables, and accompanying discussions. This circular provides background information on the investigations and integrates the published components of the resource appraisal. A comprehensive bibliography cites both specific and general references to the geology, geochemistry, geophysics, and mineral deposits of the Choteau l? x 2? quadrangle.

  5. Nature of M-Ga bonds in dihalogallyl complexes (η5-C5H5)(Me3P)2M(GaX2) (M = Fe, Ru, Os) and (η5-C5H5)(OC)2Fe(GaX2) (X = Cl, Br, I): a DFT study.

    PubMed

    Pandey, Krishna K; Patidar, Pankaj; Aldridge, Simon

    2010-11-18

    Density functional theory (DFT) calculations have been performed on the terminal dihalogallyl complexes of iron, ruthenium, and osmium (η(5)-C(5)H(5))(Me(3)P)(2)M(GaX(2)) (M = Fe, Ru, Os; X = Cl, Br, I) and (η(5)-C(5)H(5))(OC)(2)Fe(GaX(2)) (X = Cl, Br, I) at the BP86/TZ2P/ZORA level of theory. On the basis of analyses suggested by Pauling, the M-Ga bonds in all of the dihalogallyl complexes are shorter than M-Ga single bonds; moreover, on going from X = Cl to X = I, the optimized M-Ga bond distances are found to increase. From the perspective of covalent bonding, however, π-symmetry contributions are, in all complexes, significantly smaller than the corresponding σ-bonding contribution, representing only 4-10% of the total orbital interaction. Thus, in these GaX(2) complexes, the gallyl ligand behaves predominantly as a σ donor, and the short M-Ga bond lengths can be attributed to high gallium s-orbital character in the M-Ga σ-bonding orbitals. The natural population analysis (NPA) charge distributions indicate that the group 8 metal atom carries a negative charge (from -1.38 to -1.62) and the gallium atom carries a significant positive charge in all cases (from +0.76 to +1.18). Moreover, the contributions of the electrostatic interaction terms (ΔE(elstat)) are significantly larger in all gallyl complexes than the covalent bonding term (ΔE(orb)); thus, the M-Ga bonds have predominantly ionic character (60-72%). The magnitude of the charge separation is greatest for dichlorogallyl complexes (compared to the corresponding GaBr(2) and GaI(2) systems), leading to a larger attractive ΔE(elstat) term and to M-Ga bonds that are stronger and marginally shorter than in the dibromo and diiodo analogues. PMID:20977253

  6. Residual Chemoresponsiveness to Acids in the Superior Laryngeal Nerve in “Taste-Blind” (P2X2/P2X3 Double-KO) Mice

    PubMed Central

    Ohkuri, Tadahiro; Horio, Nao; Stratford, Jennifer M.; Finger, Thomas E.; Ninomiya, Yuzo

    2012-01-01

    Mice lacking both the P2X2 and the P2X3 purinergic receptors (P2X-dblKO) exhibit loss of responses to all taste qualities in the taste nerves innervating the tongue. Similarly, these mice exhibit a near total loss of taste-related behaviors in brief access tests except for a near-normal avoidance of acidic stimuli. This persistent avoidance of acids despite the loss of gustatory neural responses to sour was postulated to be due to continued responsiveness of the superior laryngeal (SL) nerve. However, chemoresponses of the larynx are attributable both to taste buds and to free nerve endings. In order to test whether the SL nerve of P2X-dblKO mice remains responsive to acids but not to other tastants, we recorded responses from the SL nerve in wild-type (WT) and P2X-dblKO mice. WT mice showed substantial SL responses to monosodium glutamate, sucrose, urea, and denatonium—all of which were essentially absent in P2X-dblKO animals. In contrast, the SL nerve of P2X-dblKO mice exhibited near-normal responses to citric acid (50 mM) although responsiveness of both the chorda tympani and the glossopharyngeal nerves to this stimulus were absent or greatly reduced. These results are consistent with the hypothesis that the residual avoidance of acidic solutions by P2X-dblKO mice may be attributable to the direct chemosensitivity of nerve fibers innervating the laryngeal epithelium and not to taste. PMID:22362867

  7. Global triplet potential energy surfaces for the N2(X1Σ) + O(3P) → NO(X2Π) + N(4S) reaction

    NASA Astrophysics Data System (ADS)

    Lin, Wei; Varga, Zoltan; Song, Guoliang; Paukku, Yuliya; Truhlar, Donald G.

    2016-01-01

    This work presents two global triplet potential energy surfaces (PESs) for the high-energy reaction N2(X1Σ) + O(3P) → NO(X2Π) + N(4S)—in particular, for the lowest energy 3A' and 3A″ PESs. In order to obtain the energies needed for fitting analytic surfaces, we carried out multireference configuration interaction (MRCI) calculations based on wave functions obtained from state-averaged complete active space self-consistent field calculations for 2280 geometries for the three lowest 3A″ states and for 2298 geometries for the three lowest 3A' states. The lowest-energy 3A' and 3A″ states at each of these geometries were then improved by applying the dynamically scaled external correlation (DSEC) method to all MRCI points, and the resulting DSEC energies were used for construction of the ground-state PES for each symmetry. The many-body component of the DSEC energies for the three-dimensional 3A' and 3A″ PESs was then least-squares fitted in terms of permutationally invariant polynomials in mixed exponential-Gaussian bond order variables. The global and local minima as well as the transition structures of both the 3A' and the 3A″ analytic PES were explored. In agreement with previous work, we find that the reverse reaction is barrierless on the 3A″ surface along the minimum energy pathway. However, we have explored several new local minima and transition structures on the 3A' PES. Furthermore, based on the newly found minima and transition structures, two independent reaction mechanisms have been illustrated for the reaction path on the 3A' PES. The analytic surfaces may be used for dynamics calculations of electronically adiabatic reactive scattering and energy transfer.

  8. LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

    PubMed

    Saji, Viswanathan S; Song, Hyun-Kon

    2015-01-01

    Electrode materials having nanometer scale dimensions are expected to have property enhancements due to enhanced surface area and mass/charge transport kinetics. This is particularly relevant to intrinsically low electronically conductive materials such as lithium iron phosphate (LiFePO4), which is of recent research interest as a high performance intercalation electrode material for Li-ion batteries. Many of the reported works on LiFePO4 synthesis are unattractive either due to the high cost of raw materials or due to the complex synthesis technique. In this direction, synthesis of LiFePO4 directly from inexpensive FePO4 shows promise.The present study reports LiFePO4 nanostructures prepared from iron (III) phosphate (FePO4 x 2H2O) by precipitation-hydrothermal method. The sintered powder was characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Inductive coupled plasma-optical emission spectroscopy (ICP-OES), and Electron microscopy (SEM and TEM). Two synthesis methods, viz. bulk synthesis and anodized aluminum oxide (AAO) template-assisted synthesis are reported. By bulk synthesis, micro-sized particles having peculiar surface nanostructuring were formed at precipitation pH of 6.0 to 7.5 whereas typical nanosized LiFePO4 resulted at pH ≥ 8.0. An in-situ precipitation strategy inside the pores of AAO utilizing the spin coating was utilized for the AAO-template-assisted synthesis. The template with pores filled with the precipitate was subsequently subjected to hydrothermal process and high temperature sintering to fabricate compact rod-like structures.

  9. Self-assembly of ligands designed for the building of a new type of [2 x 2] metallic grid. anion encapsulation and diffusion NMR spectroscopy.

    PubMed

    Manzano, Blanca R; Jalón, Félix A; Ortiz, Isabel M; Soriano, M Laura; Torre, Felipe Gómez de la; Elguero, José; Maestro, Miguel A; Mereiter, Kurt; Claridge, Tim D W

    2008-01-21

    The ligands 4,6-bis(pyrazol-1-yl)pyrimidine (bpzpm), 4,6-bis(3,5-dimethylpyrazol-1-yl)pyrimidine (bpz(*)pm), 4,6-bis(4-methylpyrazol-1-yl)pyrimidine (Mebpzpm), and 3,6-bis(3,5-dimethylpyrazol-1-yl)pyridazine (ppdMe) were synthesized and were made to react with Cu(I) centers in the presence of different counteranions. Different [2 x 2] metallic grids were obtained. With ligands bpzpm, bpz*pm, and Mebpzpm, a new type of grid was obtained where the facing ligands were divergent and two counteranions (BF(4-) or PF(6-)) were hosted in the resulting cavities and exhibit C-H...F and anion...pi interactions in the solid state. The presence of methyl groups on the pyrazolyl rings induced several distortions in the structure. In complexes with the ligand ppdMe, there were found two groups of parallel ligands in the grid, and the cavities generated were smaller. The counteranions were situated outside the grid, and the facing ligands exhibited aromatic pi-pi stacking interactions. Anion-pi interactions involving the pyridazine ring were found. The behavior in solution of the new derivatives with a special emphasis on the cation-anion interactions was studied by UV-vis and NMR spectroscopy. Diffusion NMR experiments performed for some complexes allowed us to conclude that weak cation-anion interactions exist in solution, with the counteranions undergoing fast exchange on the diffusion time scale between the free and ion-paired states.

  10. Pocatello 1/sup 0/ x 2/sup 0/ NTMS area Idaho. Data report: National Uranium Resource Evaluation program, hydrogeochemical and stream sediment reconnaissance

    SciTech Connect

    Cook, J.R.

    1980-07-01

    This data report presents results of groundwater and stream/surface sediment reconnaissance in the National Topographic Map Series (NTMS) Pocatello 1/sup 0/ x 2/sup 0/ quadrangle. Surface samples (sediment) were collected from 1701 sites. The target sampling density was one site per 16 square kilometers (six square miles). Ground water samples were collected at 381 sites. Neutron activation analysis (NAA) results are given for uranium and 16 other elements in sediments, and for uranium and 9 other elements in ground water. Mass spectrometry results are given for helium in ground water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps. Statistical summaries of data and a brief description of results are given. A generalized geologic map and a summary of the geology of the area are included. Data from sediment sites include: (1) stream water chemistry measurements where applicable (pH, conductivity, and alkalinity); and (2) elemental analyses for sediment samples (U, Th, Hf, Al, Ce, Dy, Eu, Fe, La, Lu, Mn, Sc, Sm, Na, Ti, V, and Yb). Sample site descriptors (stream characteristics, vegetation, etc.) are also tabulated. Areal distribution maps, histograms, and cumulative frequency plots for most elements; U/Th, U/Hf, and U/La ratios; and scintillometer readings for sediment sample sites are included on the microfiche. Data from groundwater sites include: (1) water chemistry measurements (pH, conductivity, and alkalinity); (2) physical measurements where applicable (water temperature, well description, and scintillometer reading); and (3) elemental analyses (U, Al, Br, Cl, Dy, F, He, Mg, Mn, Na, and V). Data from stream water sites include: (1) water chemistry measurements (pH, conductivity, and alkalinity); and (2) elemental analyses (U, Al, Br, Cl, F, Mg, Mn, Na, and V).

  11. Jet-Cooled Cavity Ring-Down Spectroscopy of the ~a ^2E^"-~X ^2A_2^' Vibronic Transition of NO_3

    NASA Astrophysics Data System (ADS)

    Chen, Ming-Wei; Just, Gabriel M. P.; Codd, Terrance; Miller, Terry A.

    2010-06-01

    The three energetically lowest electronic states (~X 2A2^', ~A 2E^", and ~B 2E^') of NO_3 are strongly coupled by vibronic interactions and have been treated in considerable detail theoretically. Corresponding experimental characterization of the interaction is much less detailed. Previous experimental results primarily consist of IR measurements of vibrational transitions in the ground state. In addition, the electronically forbidden ~A-~X transition has been observed in ambient temperature CRDS studies. A slit-jet nozzle with a high voltage pulsed discharge has been applied to produce the NO_3 radical by dissociating the N-O bond of N_2O_5, and the jet-cooled NO_3 CRDS absorption spectrum has been successfully observed with a high-resolution laser source (Δν≈250MHz, intrinsic resolution considering the instrumental linewidth and the residual Doppler broadening in the jet). The 4^1_0 band (parallel band) shows complex rotational structure which is presently being analyzed. The 2^1_0 band has also been measured as an example of a perpendicular band. Besides the ν_2 and ν_4 vibronic bands, the vibronically forbidden origin band (0^0_0 band) has been recorded under the same experimental conditions. The weakly observed ~A-~X origin band is likely either a magnetic dipole or an electric quardrupole transition. J. F. Stanton, J. Chem. Phys., 126, 134309 (2007) K. Kawaguchi, E. Hirota, T. Ishiwata, and I. Tanaka, J. Chem. Phys., 93, 951 (1990) K. Kawaguchi, T. Ishiwata, E. Hirota, and I. Tanaka, Chem. Phys., 231, 193 (1998) A. Deev, J. Sommar, and M. Okumura, J. Chem. Phys., 122, 224305 (2005) E. Hirota, T. Ishiwata, K. Kawaguchi, M. Fujitake, N. Ohashi, I. Tanaka, J. Chem. Phys., 107, 2829 (1997)

  12. Global triplet potential energy surfaces for the N2(X(1)Σ) + O((3)P) → NO(X(2)Π) + N((4)S) reaction.

    PubMed

    Lin, Wei; Varga, Zoltan; Song, Guoliang; Paukku, Yuliya; Truhlar, Donald G

    2016-01-14

    This work presents two global triplet potential energy surfaces (PESs) for the high-energy reaction N2(X(1)Σ) + O((3)P) → NO(X(2)Π) + N((4)S)-in particular, for the lowest energy (3)A' and (3)A″ PESs. In order to obtain the energies needed for fitting analytic surfaces, we carried out multireference configuration interaction (MRCI) calculations based on wave functions obtained from state-averaged complete active space self-consistent field calculations for 2280 geometries for the three lowest (3)A″ states and for 2298 geometries for the three lowest (3)A' states. The lowest-energy (3)A' and (3)A″ states at each of these geometries were then improved by applying the dynamically scaled external correlation (DSEC) method to all MRCI points, and the resulting DSEC energies were used for construction of the ground-state PES for each symmetry. The many-body component of the DSEC energies for the three-dimensional (3)A' and (3)A″ PESs was then least-squares fitted in terms of permutationally invariant polynomials in mixed exponential-Gaussian bond order variables. The global and local minima as well as the transition structures of both the (3)A' and the (3)A″ analytic PES were explored. In agreement with previous work, we find that the reverse reaction is barrierless on the (3)A″ surface along the minimum energy pathway. However, we have explored several new local minima and transition structures on the (3)A' PES. Furthermore, based on the newly found minima and transition structures, two independent reaction mechanisms have been illustrated for the reaction path on the (3)A' PES. The analytic surfaces may be used for dynamics calculations of electronically adiabatic reactive scattering and energy transfer.

  13. Nuclear magnetic resonance study of the magnetic line phases in SrCoO x (2.5 ≤ × ≤ 3)

    NASA Astrophysics Data System (ADS)

    Hines, W. A.; Perry, D. M.; Xie, C. K.; Budnick, J. I.; Wells, B. O.; Dabrowski, B.

    2016-07-01

    A 59Co spin-echo nuclear magnetic resonance (NMR) study, along with complimentary magnetization and x-ray diffraction characterization, is reported for three of the four magnetic line phases which occur in the hole-doped perovskite system SrCoO x , 2.5 ≤ x ≤ 3. The magnetic line phases are the single-valence state end-member compounds SrCoO2.5 and SrCoO3, as well as the mixed-valence state compound SrCoO2.88. In this work, the Co valence was varied by changing the oxygen stoichiometry through electrochemical oxidation/reduction. Antiferromagnetic SrCoO2.5, with trivalent Co3+ (3d6), is characterized by a single strong, relatively narrow, 59Co NMR peak centered at 314 MHz. The 314 MHz peak frequency can be explained using a typical 3d hyperfine coupling constant and the Co moment value ≈3 μ B obtained from neutron diffraction measurements. Ferromagnetic SrCoO3 with tetravalent Co4+ (3d5), is characterized by a single strong, relatively narrow, 59Co NMR peak centered at 93 MHz. However, the 93 MHz peak frequency is considerably smaller than expected from the 2.1 μ B Co moment values obtained from the saturation magnetization indicating a significant orbital contribution. Ferromagnetic and mixed-valent (Co3+/Co4+) SrCoO2.88 is characterized by three broad 59Co peaks, centered at 47, 134, and 280 MHz, consistent with previous reports. Based on the NMR results from the end-member compounds, the 280 MHz peak is most likely due to Co3+ and not Co4+ as previously reported.

  14. Study on electrical conductivity and phase transition in singly doped BIPBVOX (Bi2V1-xPbxO5.5-x/2) solid electrolyte

    NASA Astrophysics Data System (ADS)

    Beg, Saba; Naqvi, Faria K.; Al-Areqi, Niyazi A. S.

    2014-12-01

    Samples of bismuth lead vanadium oxide (BIPBVOX) (Bi2V1-xPbxO5.5-x/2) singly substituted system in the composition range 0.05 ≤ x ≤ 0.20 were prepared by sol-gel synthesis route. Structural investigations were carried out by using a combination of differential thermal analysis (DTA) and powder X-ray diffraction (PXRD) technique. Energy dispersive X-ray spectroscopy analysis (EDXA) of doped samples was carried out to predict the sample purity and doping concentration. Transitions, α↔β, β↔γ and γ‧↔γ were detected by XRD, DTA and variation in the Arrhenius plots of conductivity. The ionic conductivity was measured by AC impedance spectroscopy. The solid solutions with composition x ≤ 0.07 undergo α↔β phase transition, at 329 °C and β↔γ phase transition at 419 °C. The highly conducting γ‧-phase was effectively stabilized at room temperature for compositions with x ≥ 0.17 whose thermal stability increases with Pb content. At 300 °C, the highest value of conductivity 6.234 × 10-5 S cm-1 was obtained for composition x = 0.15 and at 600 °C the highest value of conductivity 0.65 S cm-1 is observed for x = 0.17. AC impedance plots reveal that the conductivity is mainly due to the grain contribution to oxide ion conductivity.

  15. Death Valley 1/sup 0/ x 2/sup 0/ NTMS area, California and Nevada. Data report: National Uranium Resource Evaluation program, hydrogeochemical and stream sediment reconnaissance

    SciTech Connect

    Cook, J.R.

    1980-04-01

    Results of ground water and stream sediment reconnaissance in the National Topographic Map Series (NTMS) Death Valley 1/sup 0/ x 2/sup 0/ quadrangle are presented. Stream sediment samples were collected from small streams at 649 sites or at a nominal density of one site per 20 square kilometers. Ground water samples were collected at 62 sites or at a nominal density of one site per 220 square kilometers. Neutron activation analysis results are given for uranium and 16 other elements in sediments, and for uranium and 8 other elements in ground water and surface water. Mass spectrometry results are given for helium in ground water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps. Statistical summaries of data and a brief description of results are given. A generalized geologic map and a summary of the geology of the area are included. Key data from ground water sites include (1) water chemistry measurements (pH, conductivity, and alkalinity), (2) scintillometer readings, and (3) elemental analyses (U, Br, Cl, F, He, Mn, Na, and V). Supplementary data include site descriptors, tabulated analytical data for Al, Dy, and Mg, and histograms and cumulative frequency plots for all elements. Key data from stream sediment sites include (1) water quality measurements (2) important elemental analyses, (U, Th, Hf, Ce, Fe, Mn, Sc, Na, Ti, and V), and (3) scintillometer readings. Supplementary data from stream sediment sites include sample site descriptors (stream characteristics, vegetation, etc.), additional elemental analyses (Dy, Eu, La, Lu, Sm, and Yb), and histograms and cumulative frequency plots for all elements.

  16. Percolating hierarchical defect structures drive phase transformation in Ce1−xGdxO2−x/2: a total scattering study

    PubMed Central

    Scavini, Marco; Coduri, Mauro; Allieta, Mattia; Masala, Paolo; Cappelli, Serena; Oliva, Cesare; Brunelli, Michela; Orsini, Francesco; Ferrero, Claudio

    2015-01-01

    A new hierarchical approach is presented for elucidating the structural disorder in Ce1−xGdxO2−x/2 solid solutions on different scale lengths. The primary goal of this investigation is to shed light on the relations between the short-range and the average structure of these materials via an analysis of disorder on the mesocopic scale. Real-space (pair distribution function) and reciprocal-space (Rietveld refinement and microstructure probing) analysis of X-ray powder diffraction data and electron spin resonance (ESR) investigations were carried out following this approach. On the local scale, Gd- and Ce-rich droplets (i.e. small regions a few ångströms wide) form, exhibiting either a distorted fluorite (CeO2) or a C-type (Gd2O3) structure in the whole compositional range. These droplets can then form C-type nanodomains which, for Gd concentrations x Gd ≤ 0.25, are embedded in the fluorite matrix. At the site percolation threshold p C for a cubic lattice (x Gd = p C ≃ 0.311), C-type nanodomains percolate inside each crystallite and a structural phase transformation is observed. When this occurs, the peak-to-peak ESR line width ΔH pp shows a step-like behaviour, which can be associated with the increase in Gd–Gd dipolar interactions. A general crystallographic rationale is presented to explain the fluorite-to-C-type phase transformation. The approach shown here could be adopted more generally in the analysis of disorder in other highly doped materials. PMID:26306193

  17. Impact of Stoichiometry of Yb2+xTi2 - xO7 - x / 2 on its Structure and Physical Properties

    NASA Astrophysics Data System (ADS)

    Arpino, Kathryn; Trump, Benjamin; McQueen, Tyrel; Broholm, Collin; Koohpayeh, Seyed

    The rare-earth pyrochlores (R2M2 O7) are topic of intense study in the field of magnetism as an ideal host for geometric frustration including spin-liquid and spin-ice behaviour. Specifically, R2Ti2O7 has proved a rich playground: compounds R = Ho and Dy are classical spin ices, R = Tb has been shown to be a spin liquid at low temperatures, and R = Yb is a candidate quantum spin ice. This system is attractive for the large anisotropic magnetic properties of rare earth ions, Ti4+'s lack of magnetic moment which isolates the magnetic ordering of R3+, and the comparative ease of making single crystals via the floating zone technique. This talk will present the structure and physical properties of a Yb2+ x Ti2- x O7-x/ 2 series including both the pure and stuffed samples. The series shows a dramatic change in the low-temperature (50-200 mK) specific heat signature upon doping away from the pure compound. Understanding the magnetic and physical properties of the off-stoichiometric series sheds light both on the magnetic ordering of the ideal spin ice candidate compound as well as aids in evaluating the quality and stoichiometry of a measured sample. In this vein, proper single-crystal growth conditions in order to ensure single crystals of appropriate stoichiometry will also be discussed. The Institute of Quantum Matter is supported by Department of Energy (DOE), Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-08ER46544.

  18. Epitaxy of CoSix (1<x<2) silicides on Si(111) studied by photoemission and extended x-ray-absorption fine-structure techniques

    NASA Astrophysics Data System (ADS)

    Pirri, C.; Hong, S.; Tuilier, M. H.; Wetzel, P.; Gewinner, G.; Cortès, R.

    1996-01-01

    Electronic and structural properties of epitaxial CoSix layers have been investigated by means of core-level and valence-band photoemission, x-ray photoelectron diffraction, and extended x-ray-absorption fine-structure (EXAFS) experiments. CoSix layers of various x compositions have been grown on silicon by low rate Co and Si co-deposition onto room-temperature Si(111) substrates, with film thicknesses ranging from 30 to 100 Å. Photoemission shows substantial differences in valence and core-level spectra with respect to those of stable fluorite-type CoSi2 and ɛ-CoSi and indicate that well-defined metastable phases are formed. In particular, core-level photoemission experiments performed with a monochromatized x-ray source show large Si 2p binding-energy shifts (~0.4 eV) in the room-temperature deposited CoSix (1<x<2), with respect to stable ɛ-CoSi and CaF2-type CoSi2. X-ray photoelectron diffraction as well as extended x-ray-absorption fine-structure measurements suggest that these pseudomorphic phases have a cubic structure, over a wide composition range. EXAFS measurements reveal that Co atoms are coordinated with eight Si atoms with a bond length of ~2.33 Å and with Co atoms with bond lengths in the 2.67-2.68 Å range. Such short Co-Co bond lengths show that the structure is definitively different from the stable CaF2-type CoSi2, even at the CoSi2 composition. All experimental data indicate that CoSix silicides crystallize in a cubic lattice close to that of pseudomorphic FeSix silicides, namely, a CsCl-type derived structure.

  19. LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

    PubMed

    Saji, Viswanathan S; Song, Hyun-Kon

    2015-01-01

    Electrode materials having nanometer scale dimensions are expected to have property enhancements due to enhanced surface area and mass/charge transport kinetics. This is particularly relevant to intrinsically low electronically conductive materials such as lithium iron phosphate (LiFePO4), which is of recent research interest as a high performance intercalation electrode material for Li-ion batteries. Many of the reported works on LiFePO4 synthesis are unattractive either due to the high cost of raw materials or due to the complex synthesis technique. In this direction, synthesis of LiFePO4 directly from inexpensive FePO4 shows promise.The present study reports LiFePO4 nanostructures prepared from iron (III) phosphate (FePO4 x 2H2O) by precipitation-hydrothermal method. The sintered powder was characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Inductive coupled plasma-optical emission spectroscopy (ICP-OES), and Electron microscopy (SEM and TEM). Two synthesis methods, viz. bulk synthesis and anodized aluminum oxide (AAO) template-assisted synthesis are reported. By bulk synthesis, micro-sized particles having peculiar surface nanostructuring were formed at precipitation pH of 6.0 to 7.5 whereas typical nanosized LiFePO4 resulted at pH ≥ 8.0. An in-situ precipitation strategy inside the pores of AAO utilizing the spin coating was utilized for the AAO-template-assisted synthesis. The template with pores filled with the precipitate was subsequently subjected to hydrothermal process and high temperature sintering to fabricate compact rod-like structures. PMID:26328435

  20. Effect of chemical ordering on the crystallization behavior of Se90Te10-xSnx (x=2, 4, 6, and 8) chalcogenide glasses

    NASA Astrophysics Data System (ADS)

    Lafi, Omar A.; Imran, Mousa M. A.; Abu-Shaweesh, Nazem I.; Al-Kurdi, Fares M.; Khatatbeh, Ibtehaj K.

    2014-06-01

    Ternary Se90Te10-xSnx (x=2, 4, 6, and 8) chalcogenide glassy alloys have been prepared by melt quenching technique. Various crystallization parameters, such as onset (Tc) and peak (Tp) crystallization temperatures, activation energy of crystallization (Ec) and Avrami exponent (n) have been determined for these alloys. Tc and Tp have been determined directly from the non-isothermal differential scanning calorimeter (DSC) thermograms. The value of Ec has been calculated from the variation of both Tc and Tp with the heating rate (β) according to Kissinger, Takhor, Augis-Bennett and Ozawa models while Augis-Bennett method has been used to deduce the value of n for the studied samples. The obtained values of the crystallization parameters have been correlated with the character and the energy of the chemical bonds through the calculation of the heteronuclear bond energies of the constituent atoms using Pauling principle. In addition to that, Tichy-Ticha model was used to estimate the mean bond energy of the average cross-linking per atom , the average bond energy per atom of the remaining matrix , and the overall mean bond energy of the studied glasses. Results reveal that both of Tc and Tp decreases with increases Sn content. This is may be attributed to the decreasing in the overall mean bond energy . Besides, the plot of Ec (and also Tg) against was found to be non linear, which contradicts the well known linear correlation between Ec and Tg with as suggested by Tichy-Ticha model. This discrepancy may be due to the fact that the Tichy-Ticha linear correlation model was based on the assumption of covalent glassy network, while in the present glassy alloys, Se-Te binary doped with heavy elements such as Sn exhibit iono-covalent bonding. The calculated values of the ionicity are in support of this argument.

  1. Inelastic scattering of He atoms and NO(X2Pi) molecules: the role of parity on the differential cross section.

    PubMed

    Aoiz, F J; Verdasco, J E; Brouard, M; Kłos, J; Marinakis, S; Stolte, S

    2009-12-31

    Quasiclassical trajectory (QCT) and quantum mechanical (QM) close-coupling calculations have been used to study the state-resolved rotationally inelastic scattering of NO(X(2)Pi(1/2),v = 0,j = 1/2,e/f) by He on the most recent ab initio potential energy surface of J. Kłos et al. [J. Chem. Phys. 2000, 112, 2195.]. Opacity functions, and integral and differential cross sections are reported at collision energies of 63 and 147 meV and compared with previous theoretical calculations and experimental measurements on this and other systems. The existence of double peaks in the QCT and QM differential cross sections is examined in detail. While at a collision energy of 147 meV two rotational peaks appear in both the QCT and open-shell QM results, only a single peak is found in the QM calculations at the lower collision energy. The double peaks in the quantum-state-resolved differential cross sections (DCS) are found to be closely related to structure found in the corresponding state-resolved opacity functions. The structure in the QCT and QM DCSs is attributed to a flattening of the potential energy surface for sideways approach of He to the near-symmetric NO(X) molecule, and in both sets of calculations, it is shown to arise from a specific odd term in the expansion of the intermolecular potential. Although significant differences are found between the QCT and QM data in the forward scattered direction, and for higher final rotational levels, reflecting differences in the nature of the rotational rainbows observed in these two methods, in general, the QCT calculations are shown to give similar results to quantum theory. Furthermore, they provide valuable clues as to the mechanism of rotational energy transfer in this system. PMID:19673507

  2. Interleukin-8 production by the human colon epithelial cell line HT-29: modulation by interleukin-13.

    PubMed Central

    Kolios, G.; Robertson, D. A.; Jordan, N. J.; Minty, A.; Caput, D.; Ferrara, P.; Westwick, J.

    1996-01-01

    1. We have determined which cytokines induce and modulate the production of the chemokine interleukin-8 (IL-8) by the human colonic epithelial cell line HT-29. 2. Growth arrested cell cultures were stimulated with the human recombinant cytokines interleukin-1 alpha (IL-1 alpha), tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-13 (IL-13), interleukin-10 (IL-10) or vehicle added alone or in combination. The production of IL-8 was determined by enzyme-linked immunosorbent assay (ELISA) and IL-8 messenger RNA expression by Northern blot analysis. 3. The production of IL-8 in unstimulated cells was undetectable by both ELISA and Northern blot analysis. 4. HT-29 cells produced IL-8 following stimulation with IL-1 alpha or TNF-alpha in a time- and a concentration-dependent manner, while IFN-gamma, IL-10 and IL-13 did not induce IL-8 production by HT-29 cells. 5. IL-13 was found to up-regulate significantly (P < 0.01) the IL-1 alpha but not the TNF-alpha-induced IL-8 generation by HT-29 cells. In contrast, IL-10 had no effect on either IL-1 alpha or TNF-alpha-induced IL-8 production. 6. Experiments using cycloheximide demonstrated that this synergistic effect of IL-13 and IL-1 alpha on IL-8 secretion was not through de novo protein synthesis. Using actinomycin-D, we demonstrated that the IL-13 up-regulation was at the level of transcription rather than messenger RNA stability. 7. These findings suggest that colonic epithelial cells have a functional IL-13 receptor, which is coupled to an up-regulation of IL-1 alpha, but not TNF-alpha induced IL-8 generation. Images Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 PMID:8886420

  3. H + O3 Fourier-transform infrared emission and laser absorption studies of OH(X2Pi) radical - An experimental dipole moment function and state-to-state Einstein A coefficients

    NASA Technical Reports Server (NTRS)

    Nelson, David D., Jr.; Schiffman, Aram; Nesbitt, David J.; Orlando, John J.; Burkholder, James B.

    1990-01-01

    FTIR emission/absorption spectroscopy is used to measure the relative intensities of 88 pairs of rovibrational transitions of OH(X2Pi) distributed over 16 vibrational bands. The experimental technique used to obtain the Einstein A ratios is discussed. The dipole moment function which follows from the intensity ratios along with Einstein A coefficients calculated from mu(r) is presented.

  4. Direct observation of the fundamental vibration-rotation transitions within the NiD X2Δ ground state by CO-Faraday-L.M.R. spectroscopy and zero field transitions in NiH

    NASA Astrophysics Data System (ADS)

    Lipus, K.; Simon, U.; Bachem, E.; Nelis, Th.; Urban, W.

    We report the first direct observation of the vibration-rotation spectrum of nickel-deuteride in its X2Δ ground state by CO-Faraday-L.M.R. spectroscopy. A set of effective molecular parameters is given. We present first results on the vibration-rotation spectroscopy of NiH, employing a tunable diode laser spectrometer.

  5. The rotational spectrum of the CCP (X 2Pi(r)) radical and its 13C isotopologues at microwave, millimeter, and submillimeter wavelengths.

    PubMed

    Halfen, D T; Sun, M; Clouthier, D J; Ziurys, L M

    2009-01-01

    The pure rotational spectrum of CCP (X (2)Pi(r)) has been measured at microwave, millimeter, and submillimeter wavelengths (17-545 GHz), along with its (13)C isotopologues ((13)C(13)CP, C(13)CP, and (13)CCP). The spectra of these species were recorded using a combination of millimeter/submillimeter direct absorption methods and Fourier transform microwave (FTMW) techniques. The phosphorus dicarbides were created in the gas phase from the reaction of red phosphorus and acetylene or methane in argon in an ac discharge for the direct absorption experiments, and using PCl(3) as the phosphorus source in a pulsed dc nozzle discharge for the FTMW measurements. A total of 35 rotational transitions were recorded for the main isotopologue, and between 2 and 8 for the (13)C-substituted species. Both spin-orbit components were identified for CCP, while only the Omega = 12 ladder was observed for (13)C(13)CP, C(13)CP, and (13)CCP. Hyperfine splittings due to phosphorus were observed for each species, as well as carbon-13 hyperfine structure for each of the (13)C-substituted isotopologues. The data were fitted with a Hund's case (a) Hamiltonian, and rotational, fine structure, and hyperfine parameters were determined for each species. The r(m)(1) bond lengths established for CCP, r(C-C) = 1.289(1) A and r(C-P) = 1.621(1) A, imply that there are double bonds between both the two carbon atoms and the carbon and phosphorus atoms. The hyperfine constants suggest that the unpaired electron in this radical is primarily located on the phosphorus nucleus, but with some electron density also on the terminal carbon atom. There appears to be a minor resonance structure where the unpaired electron is on the nucleus of the end carbon. The multiple double bond structure forces the molecule to be linear, as opposed to other main group dicarbides, such as SiC(2), which have cyclic geometries.

  6. The Fourier transform microwave spectrum of the arsenic dicarbide radical (CCAs: X (2)Pi(1/2)) and its (13)C isotopologues.

    PubMed

    Sun, M; Clouthier, D J; Ziurys, L M

    2009-12-14

    The pure rotational spectrum of the CCAs radical in its ground electronic and spin state, X (2)Pi(12), has been measured using Fourier transform microwave techniques in the frequency range of 12-40 GHz. This species was created in a supersonic expansion from a reaction mixture of AsCl(3) and C(2)H(2) or CH(4) diluted in high pressure argon, using a pulsed nozzle containing a dc discharge source. Three rotational transitions were measured for the main isotopologue, (12)C(12)CAs, in the Omega=12 ladder; both lambda-doubling and arsenic (I=32) hyperfine interactions were observed in these spectra. In addition, two to four rotational transitions were recorded for the (13)C(13)CAs, (13)C(12)CAs, and (12)C(13)CAs species. In these three isotopologues, hyperfine splittings were also resolved arising from the (13)C nuclei (I=12), creating complex spectral patterns. The CCAs spectra were analyzed with a case (a) Hamiltonian, and effective rotational, lambda-doubling, and arsenic and carbon-13 hyperfine constants were determined for the Omega=12 ladder. From the effective rotational constants of the four isotopologues, an r(m) ((1)) structure has been derived with r(C-C)=1.287 A and r(C-As)=1.745 A. These bond lengths indicate that the predominant structure for arsenic dicarbide is C=C=As, with some contributing C[Triple Bond]C and C[Triple Bond]As triple bond characters. The hyperfine constants established in this work indicate that about 23 of the unpaired electron density lies on the arsenic atom, with the remaining percentage on the terminal carbon. The value of the arsenic quadrupole coupling constant (eqQ=-202 MHz) suggests that the As-C bond has a mixture of covalent and ionic characters, consistent with theoretical predictions that both pi backbonding and electron transfer play a role in creating a linear, as opposed to a cyclic, structure for certain heteroatom dicarbides.

  7. The crystal chemistry of Ca(10-y)(SiO4)3(SO4)3Cl(2-x-2y)F(x) ellestadite.

    PubMed

    Fang, Yanan; Ritter, Clemens; White, Tim

    2011-12-19

    Fluor-chlorellestadite solid solutions Ca(10)(SiO(4))(3)(SO(4))(3)Cl(2-x)F(x), serving as prototype crystalline matrices for the fixation of hazardous fly ash, were synthesized and characterized by powder X-ray and neutron diffraction (PXRD and PND), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The lattice parameters of the ellestadites vary linearly with composition and show the expected shrinkage of unit cell volume as fluorine (IR = 1.33 Å) displaces chlorine (IR = 1.81 Å). FTIR spectra indicate little or no OH(-) in the solid solutions. All compositions conform to P6(3)/m symmetry where F(-) is located at the 2a (0, 0, (1)/(4)) position, while Cl(-) is displaced out of the 6h Ca(2) triangle plane and occupies 4e (0, 0, z) split positions with z ranging from 0.336(3) to 0.4315(3). Si/S randomly occupy the 6h tetrahedral site. Ellestadites rich in Cl (x ≤ 1.2) show an overall deficiency in halogens (<2 atom per formula unit), particularly Cl as a result of CaCl(2) volatilization, with charge balance achieved by the creation of Ca vacancies (Ca(2+) + 2Cl(-) →□(Ca) + 2□(Cl)) leading to the formula Ca(10-y)(SiO(4))(3)(SO(4))(3)Cl(2-x-2y)F(x). For F-rich compositions the vacancies are found at Ca(2), while for Cl-rich ellestadites, vacancies are at Ca(1). It is likely the loss of CaCl(2) which leads tunnel anion vacancies promotes intertunnel positional disorder, preventing the formation of a P2(1)/b monoclinic dimorph, analogous to that reported for Ca(10)(PO(4))(6)Cl(2). Trends in structure with composition were analyzed using crystal-chemical parameters, whose systematic variations served to validate the quality of the Rietveld refinements. PMID:22111559

  8. The crystal chemistry of Ca(10-y)(SiO4)3(SO4)3Cl(2-x-2y)F(x) ellestadite.

    PubMed

    Fang, Yanan; Ritter, Clemens; White, Tim

    2011-12-19

    Fluor-chlorellestadite solid solutions Ca(10)(SiO(4))(3)(SO(4))(3)Cl(2-x)F(x), serving as prototype crystalline matrices for the fixation of hazardous fly ash, were synthesized and characterized by powder X-ray and neutron diffraction (PXRD and PND), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The lattice parameters of the ellestadites vary linearly with composition and show the expected shrinkage of unit cell volume as fluorine (IR = 1.33 Å) displaces chlorine (IR = 1.81 Å). FTIR spectra indicate little or no OH(-) in the solid solutions. All compositions conform to P6(3)/m symmetry where F(-) is located at the 2a (0, 0, (1)/(4)) position, while Cl(-) is displaced out of the 6h Ca(2) triangle plane and occupies 4e (0, 0, z) split positions with z ranging from 0.336(3) to 0.4315(3). Si/S randomly occupy the 6h tetrahedral site. Ellestadites rich in Cl (x ≤ 1.2) show an overall deficiency in halogens (<2 atom per formula unit), particularly Cl as a result of CaCl(2) volatilization, with charge balance achieved by the creation of Ca vacancies (Ca(2+) + 2Cl(-) →□(Ca) + 2□(Cl)) leading to the formula Ca(10-y)(SiO(4))(3)(SO(4))(3)Cl(2-x-2y)F(x). For F-rich compositions the vacancies are found at Ca(2), while for Cl-rich ellestadites, vacancies are at Ca(1). It is likely the loss of CaCl(2) which leads tunnel anion vacancies promotes intertunnel positional disorder, preventing the formation of a P2(1)/b monoclinic dimorph, analogous to that reported for Ca(10)(PO(4))(6)Cl(2). Trends in structure with composition were analyzed using crystal-chemical parameters, whose systematic variations served to validate the quality of the Rietveld refinements.

  9. Magnetic properties after irradiation of 1:4 complexes consisting of CoX2, X=NCS⁻, Cl⁻, and NCO⁻, and phenylpyridyldiazomethane in dilute frozen solutions: axial ligand effect in heterospin single-molecule magnets.

    PubMed

    Karasawa, Satoru; Koga, Noboru

    2011-06-01

    The solutions of 1:4 complexes of Co(X)(2)(D1py)(4), X = Cl(-), and NCO(-) and D1py = phenylpyridyldiazomethane, were photolyzed under cryogenic conditions, and their magnetic properties were investigated by direct current (DC) and alternating current (AC) magneto/susceptometries. After irradiation, the resulting cobalt-carbene complexes, Co(X)(2)(C1py)(4), exhibited the behaviors of heterospin single-molecule magnets (SMMs) strongly depending on the axial ligands. In Co(X)(2)(C1py)(4): X = Cl(-) and NCO(-), the effective activation barriers, U(eff), for the reorientation of the magnetic moment and the resonant quantum tunneling time, τ(Q), characteristic to SMM properties were estimated to be 91 and 130 K, and 4 × 10(3) and 2 × 10(5) s, respectively. The τ(Q) of Co(NCS)(2)(C1py)(4) with U(eff) = 89 K was found to be 6 × 10(2) s. In Co(X)(2)(C1py)(4): X = Cl(-) and NCO(-), temperature-dependent hysteresis loops were also observed below the blocking temperature (T(B) = 3.2 and 4.8 K, respectively) and the coercive forces, H(c), of 7.0 and 20 kOe at 1.9 K, respectively, were obtained. In a series of 1:4 complexes of Co(X)(2)(C1py)(4), X = NCS(-), Cl(-), and NCO(-), the axial ligands strongly affected the heterospin SMM properties, and the NCO(-) ion having the large magnitude of the ligand-field splitting in a spectrochemical series, gave the largest U(eff) and H(c) and the longest τ(Q).

  10. High-throughput screening platform for natural product-based drug discovery against 3 neglected tropical diseases: human African trypanosomiasis, leishmaniasis, and Chagas disease.

    PubMed

    Annang, F; Pérez-Moreno, G; García-Hernández, R; Cordon-Obras, C; Martín, J; Tormo, J R; Rodríguez, L; de Pedro, N; Gómez-Pérez, V; Valente, M; Reyes, F; Genilloud, O; Vicente, F; Castanys, S; Ruiz-Pérez, L M; Navarro, M; Gamarro, F; González-Pacanowska, D

    2015-01-01

    African trypanosomiasis, leishmaniasis, and Chagas disease are 3 neglected tropical diseases for which current therapeutic interventions are inadequate or toxic. There is an urgent need to find new lead compounds against these diseases. Most drug discovery strategies rely on high-throughput screening (HTS) of synthetic chemical libraries using phenotypic and target-based approaches. Combinatorial chemistry libraries contain hundreds of thousands of compounds; however, they lack the structural diversity required to find entirely novel chemotypes. Natural products, in contrast, are a highly underexplored pool of unique chemical diversity that can serve as excellent templates for the synthesis of novel, biologically active molecules. We report here a validated HTS platform for the screening of microbial extracts against the 3 diseases. We have used this platform in a pilot project to screen a subset (5976) of microbial extracts from the MEDINA Natural Products library. Tandem liquid chromatography-mass spectrometry showed that 48 extracts contain potentially new compounds that are currently undergoing de-replication for future isolation and characterization. Known active components included actinomycin D, bafilomycin B1, chromomycin A3, echinomycin, hygrolidin, and nonactins, among others. The report here is, to our knowledge, the first HTS of microbial natural product extracts against the above-mentioned kinetoplastid parasites.

  11. Bacon Production: Evaluating Potential Processing and Management Practices to Improve Product Quality of Industrial Sliced Bacon

    ERIC Educational Resources Information Center

    Scramlin, Stacy Maurine

    2009-01-01

    The objective of this research was to determine areas of improvement to bacon production. The first trial was conducted to determine differences in belly and bacon quality traits in pigs fed ractopamine (RAC) for various durations during finishing. A 2x3x2 factorial arrangement was used with barrows and gilts, fed RAC levels of 0.0, 5.0, or 7.4…

  12. Mechanism of single metal exchange in the reactions of [M4(SPh)10]2- (M = Zn or Fe) with CoX2 (X = Cl or NO3) or FeCl2.

    PubMed

    Autissier, Valerie; Henderson, Richard A

    2008-07-21

    The kinetics of the reactions between [Zn4(SPh)10](2-) and an excess of MX2 (M = Co, X = NO3 or Cl; M = Fe, X = Cl), in which a Zn(II) is replaced by M(II), have been studied in MeCN at 25.0 degrees C. (1)H NMR spectroscopy shows that the ultimate product of the reactions is an equilibrium mixture of clusters of composition [Zn(n)M(4-n)(SPh)10](2-), and this is reflected in the multiphasic absorbance-time curves observed over protracted times (several minutes) using stopped-flow spectrophotometry to study the reactions. The kinetics of only the first phase have been determined, corresponding to the equilibrium formation of [Zn3M(SPh)10](2-). The effects of varying the concentrations of cluster, MX2, and ZnCl2 on the kinetics have been investigated. The rate law is consistent with the equilibrium nature of the metal exchange process and indicates a mechanism for the formation of [Zn3M(SPh)10](2-) involving two coupled equilibria. In the initial step binding of MX2 to a bridging thiolate in [Zn4(SPh)10](2-) results in breaking of a Zn-bridging thiolate bond. In the second step replacement of the cluster Zn involves transfer of the bridging thiolates from the Zn to M, with breaking of a Zn-bridged thiolate bond being rate-limiting. The kinetics for the reaction of ZnCl2 with [Zn3M(SPh)10](2-) (M = Fe or Co)} depends on the identity of M. This behavior indicates attack of ZnCl2 at a M-mu-SPh-Zn bridged thiolate. Similar studies on the analogous reactions between [Fe4(SPh)10](2-) and an excess of CoX2 (X = NO3 or Cl) in MeCN exhibit simpler kinetics but these are also consistent with the same mechanism.

  13. Hydrogen production by photosynthetic microorganisms

    SciTech Connect

    Akano, T.; Fukatsu, K.; Miyasaka, H. |

    1996-12-31

    Hydrogen is a clean energy alternative to the fossil fuels, the main source of greenhouse gas emissions. We developed a stable system for the conversion of solar energy into hydrogen using photosynthetic microorganisms. Our system consists of the following three stages: (1) Photosynthetic starch accumulation in green microalgae (400 L x2); (2) Dark anaerobic fermentation of the algal starch biomass to produce hydrogen and organic compounds (155 L x2); and (3) Further conversion of the organic compounds to produce hydrogen using photosynthetic bacteria (three types of reactors, parallel plate, raceway, and tubular). We constructed a test plant of this process at Nankoh power plant of Kansai Electric Power Company in Osaka, Japan, and carried out a series of tests using CO{sub 2} obtained from a chemical absorption pilot-plant. The photobiological hydrogen production process used a combination of a marine alga, Chlamydomonas sp. MGA 161 and marine photosynthetic bacterium, Rhodopseudomonas sp. W-1S. The dark anaerobic fermentation of algal starch biomass was also investigated. Sustained and stable starch accumulation, starch degradation in the algal cell, and hydrogen production from algal fermentation and photosynthetic bacteria in the light were demonstrated during several experiments. 3 refs., 12 figs., 1 tab.

  14. Actinomycin D blocks formation of memory of shock-avoidance in goldfish.

    PubMed

    Agranoff, B W; Davis, R E; Casola, L; Lim, R

    1967-12-22

    When 2 micrograms of antinomycin D was injected intracranially into goldfish immediately after a training session, the formation of long-term memory of a shock-avoidance was blocked. The results are discussed in relation to similar findings with acetoxycycloheximide and puromycin in the goldfish and with apparently conflicting results in the mouse.

  15. Infrared Spectra and Density Functional Calculations for Singlet CH2═SiX2 and Triplet HC-SiX3 and XC-SiX3 Intermediates in Reactions of Laser-Ablated Silicon Atoms with Di-, Tri-, and Tetrahalomethanes.

    PubMed

    Cho, Han-Gook; Andrews, Lester

    2016-03-21

    Reactions of laser-ablated silicon atoms with di-, tri-, and tetrahalomethanes in excess argon were investigated, and the products were identified from the matrix infrared spectra, isotopic shifts, and density functional theory energy, bond length, and frequency calculations. Dihalomethanes produce planar singlet silenes (CH2═SiX2), and tri- and tetrahalomethanes form triplet halosilyl carbenes (HC-SiX3 and XC-SiX3). The Si-bearing molecules identified are the most stable, lowest-energy product in the reaction systems. While the C-Si bond in the silene is a true double bond, the C-Si bond in the carbene is a shortened single bond enhanced by hyperconjugation of the two unpaired electrons on C to σ*(Si-X) orbitals, which contributes stabilization through a small amount of π-bonding and reduction of the HCSi or XCSi angles. The C-Si bond lengths in these carbenes (1.782 Å for HC-SiF3) are between the single-bond length in the unobserved first insertion intermediate (1.975 Å for CHF2-SiF) and the double-bond length in the silene (1.704 Å for CHF═SiF2). The silicon s(2)p(2) and titanium s(2)d(2) electron configurations produce similar primary products, but the methylidyne with Ti has a bond to carbon stronger than that of the halosilyl carbene.

  16. Oxygen trapping and cation site-splitting in Y(2-x)PrxO3+δ (0.0≤x<2.0 and δ≤1.0)

    NASA Astrophysics Data System (ADS)

    Lussier, Joey A.; Devitt, Graham; Szkop, Kevin M.; Bieringer, Mario

    2016-10-01

    The reduction and oxidation of the solid solution Y2-xPrxO3+δ (0.0≤x<2.0 and δ≤1.0) is investigated with emphasis on potential solid state electrolyte applications in solid oxide fuel cells. The fully reduced solid solution Y2-xPrxO3 (0.0≤x<2.0) crystallizes in the bixbyite structure (Ia 3 bar) . The oxidized solid solution Y2-xPrxO3+δ (0.0≤x<1.4) forms bixbyite phases (Ia 3 bar) whereas Y2-xPrxO3+δ (1.4≤x<2) compositions form fully disordered defect fluorite structures (Fm 3 bar m) with variable oxide defect concentrations. The two cation positions are investigated in detail using synchrotron powder X-ray and time of flight neutron diffraction data. In the bixbyite structures the 8c cation site splits into the 16c cation site and the 24d cation position migrates toward the ideal fluorite coordination upon oxidation. Reductive in-situ diffraction experiments reveal the co-existence of the fluorite and bixbyite structure only in a narrow temperature range. During oxidation of the bixbyite phase a new 16c oxide anion site is populated. The impact of the 16c oxide site population on the cation sublattice is being discussed.

  17. Characterization of the minimum energy paths for the reactions of CH(X 2Π) and 1CH2 with C2H2

    NASA Astrophysics Data System (ADS)

    Walch, Stephen P.

    1995-10-01

    The reactions of CH(2Π) and singlet methylene (1CH2) with acetylene lead to intermediates which may be important in soot formation. CH(2Π)+acetylene leads to CHCHCH (C3H3), CHCCH, CH2CC, and propargyl (CH2CCH). 1CH2+acetylene leads to cyclopropene, allene, and propyne. Except for CHCCH, which involves a barrier of 7.5 kcal/mol with respect to reactants, all of these reaction products are formed with no barrier. Miller and Melius have previously discussed the dimerization of propargyl to give benzene. C3H3 and CHCCH are shown to dimerize with no barrier to give benzene and para-benzyne, respectively. C3H3, CHCCH, and CH2CC can also add to smaller polycyclic aromatic hydrocarbons (PAH), and may be important species in forming larger PAH or fullerenes.

  18. 78 FR 12354 - Certain Microprocessors, Components Thereof, and Products Containing Same; Termination of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-22

    ..., Pennsylvania (``X2Y''). 76 FR 39,895 (July 7, 2011). The respondents are Intel Corporation and Intel America... COMMISSION Certain Microprocessors, Components Thereof, and Products Containing Same; Termination of... microprocessors, Apple Inc. of Cupertino, California (``Apple''); and Hewlett-Packard Company of Palo...

  19. Intestinal microbial affects of yeast products on weaned and transport stressed pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Study objectives were to determine effects of a commercially available yeast product (XPC, Diamond-V Mills) and stress of transportation on total Enterobacteriaceae, Escherichia coli, coliforms, and Lactobacilli populations in the intestine of weaning pigs. In a RCB design with a 2 x 2 factorial ar...

  20. The Conterminous United States Mineral Assessment Program; background information to accompany folio of geologic, geochemical, geophysical, remote sensing, and mineral resource maps of the Wallace 1 degree x 2 degrees Quadrangle, Montana and Idaho

    USGS Publications Warehouse

    Harrison, Jack Edward; Leach, David L.; Kleinkopf, M. Dean; Long, Carl L.; Rowan, Larry C.; Marvin, Richard F.

    1986-01-01

    The Wallace 1? x 2 quadrangle in Montana and Idaho was studied by an interdisciplinary research team that included geologists, geochemists, and geophysicists, as well as specialists in isotopic dating and remote sensing. The basic data resulting from these studies, as well as the final metallic mineral resource assessments, are published as a folio of maps, figures, tables, and accompanying discussions. This circular provides background information on the studies and lists the published components of the resource appraisal. An extensive bibliography lists both specific and general references that apply to this geoscience study of the quadrangle.

  1. Kinetics of the radical-radical reaction, O(3P(J)) + OH(X2Pi omega) --> O2 + H, at temperatures down to 39 K.

    PubMed

    Carty, David; Goddard, Andrew; Köhler, Sven P K; Sims, Ian R; Smith, Ian W M

    2006-03-01

    The kinetics of the reaction between O atoms and OH radicals, both in their electronic ground state, have been investigated at temperatures down to ca. 39 K. The experiments employed a CRESU (Cinétique deRéaction en Ecoulement Supersonique Uniforme) apparatus to attain low temperatures. Both reagents were created using pulsed laser photolysis at 157.6 nm of mixtures containing H2O and O2 diluted in N2 carrier gas. OH radicals were formed by both direct photolysis of H2O and the reaction between O(1D) atoms and H2O. O(3P) atoms were formed both as a direct product of O2 photolysis and by the rapid quenching of O(1D) atoms formed in that photolysis by N2 and O2. The rates of removal of OH radicals were observed by laser-induced fluorescence, and concentrations of O atoms were estimated from a knowledge of the absorption cross-section for O2 at 157.6 nm and of the measured fluence from the F2 laser at this wavelength. To obtain a best estimate of the rate constants for the O + OH reaction, we had to correct the raw experimental data for the following: (a) the decrease in the laser fluence along the jet due to the absorption by O2 in the gas mixture, (b) the increase in temperature, and consequent decrease in gas density, as a result of energy released in the photochemical and chemical processes that occurred, and (c) the formation of OH(v = 0) as a result of relaxation, particularly by O2, of OH radicals formed in levels v > 0. Once these corrections were made, the rate constant for reaction between OH and O(3P) atoms showed little variation in the temperature range of 142 to 39 K and had a value of (3.5 +/- 1.0) x 10(-11) cm3 molecule(-1) s(-1). It is recommended that this value is used in future chemical models of dense interstellar clouds.

  2. Measurement of absolute state-to-state rate constants for collision-induced transitions between spin-orbit and rotational states of NO(X 2Π, v = 2)

    NASA Astrophysics Data System (ADS)

    Sudbø, Aa. S.; Loy, M. M. T.

    1982-04-01

    Using a pulsed, time resolved IR-UV double resonance technique, we have measured initial and final state specific rates for collision-induced rotational and spin-orbit transitions in NO in its (X 2Π, v = 2) vibronic state. A systematic study of the rates was done for initial and final rotational states with J between 1/2 and 35/2, for both Ω = 1/2 and the Ω = 3/2 spin-orbit components of the X 2Π state. Collision partners were room temperature NO, He, Ar, N2, CO, and SF6. No propensity rules favoring ΔΩ = 0 or ΔJ = 0,±1 were observed, except in NO-He collisions, where ΔΩ = 0 was favored. The state-to-state rates do not vary much with initial state and fall off slowly with increasing ΔJ. Total cross sections for collision-induced rotational transitions were found to be tens of Å2, insensitive to initial state, and correlated with the size of the collision partner.

  3. Cu substitution effects on the local magnetic properties of Ba(Fe(1-x)Cu(x))(2)As(2): a site-selective (75)As and (63)Cu NMR study.

    PubMed

    Takeda, Hikaru; Imai, Takashi; Tachibana, Makoto; Gaudet, Jonathan; Gaulin, Bruce D; Saparov, Bayrammurad I; Sefat, Athena S

    2014-09-12

    We take advantage of the site-selective nature of the ^{75}As and ^{63}Cu NMR techniques to probe the Cu substitution effects on the local magnetic properties of the FeAs planes in Ba(Fe_{1-x}Cu_{x})_{2}As_{2}. We show that the suppression of antiferromagnetic Fe spin fluctuations induced by Cu substitution is weaker than a naive expectation based on a simple rigid band picture, in which each Cu atom would donate three electrons to the FeAs planes. Comparison between ^{63}Cu and ^{75}As NMR data indicates that spin fluctuations are suppressed at the Cu and their neighboring Fe sites in the tetragonal phase, suggesting the strongly local nature of the Cu substitution effects. We attribute the absence of a large superconducting dome in the phase diagram of Ba(Fe_{1-x}Cu_{x})_{2}As_{2} to the emergence of a nearly magnetically ordered FeAs plane under the presence of orthorhombic distortion.

  4. Engineering oxygen vacancies towards self-activated BaLuAl(x)Zn(4-x)O(7-(1-x)/2) photoluminescent materials: an experimental and theoretical analysis.

    PubMed

    Ma, Lan; Xia, Zhiguo; Atuchin, Victor; Molokeev, Maxim; Auluck, S; Reshak, A H; Liu, Quanlin

    2015-12-14

    Novel self-activated yellow-emitting BaLuAlxZn4-xO7-(1-x)/2 photoluminescent materials were investigated by a combined experimental and theoretical analysis. The effects of Al/Zn composition modulation, calcination atmosphere and temperature on the crystal structure and photoluminescence properties have been studied via engineering oxygen vacancies. Accordingly, BaLuAl0.91Zn3.09O7 prepared in an air atmosphere was found to be the stable crystalline phase with optimal oxygen content and gave a broad yellow emission band with a maximum at 528 nm. The self-activated luminescence mechanism is ascribed to the O-vacancies based on the density functional theory (DFT) calculation. A theoretical model originating from the designed oxygen vacancies has been proposed in order to determine the influence of O-vacancies on the band structure and self-activated luminescence. Therefore, the appearance of a new local energy level in the band gap will cause the wide-band optical transitions in the studied BaLuAlxZn4-xO7-(1-x)/2 materials.

  5. Ab initio calculations on potential energy curves and radiative lifetimes for the band systems A(2)Π-X(2)Σ(+) of magnesium monohalides MgX (X=F, Cl, Br, I).

    PubMed

    Wu, Dong-lan; Tan, Bin; Qin, Jiu-ying; Wan, Hui-jun; Xie, An-dong; Yan, Bing; Ding, Da-jun

    2015-11-01

    Ab initio calculations on potential energy curves (PECs), spectroscopic constants, transition dipole moments, radiative transition probabilities and lifetimes for the ground state (X(2)Σ(+)) and the first excited state (A(2)Π) of MgX (X=F, Cl, Br, I) molecules are determined by high-level internally contracted multi-reference configuration interaction (ic-MRCI) method. In order to improve the calculation, the Davidson modification (+Q) and scalar relativistic correction are included. The present results show that most of spectroscopic constants are in accordance with the measurements, the equilibrium internuclear distance Re increases while the other spectroscopic constants reduce along with the increasing of the atomic number of the halogen from F to I. Diagonal vibrational transitions are found to be dominant for the A(2)Π→X(2)Σ(+) system of MgX molecules. The corresponding radiative lifetimes of ν'=0 are computed to be 7.24, 9.98, 18.94 and 22.72 ns for MgF, MgCl, MgBr, and MgI, respectively. The calculated result of MgF molecule is in good agreement with the recent theoretical result of 7.16 ns, with a small relative error percent of 1.11%.

  6. The design, implementation and testing of the thermal control system of the CanX-2 nanosatellite, and, The preliminary design of the attitude determination and control system for the generic nanosatellite bus

    NASA Astrophysics Data System (ADS)

    Sarda, Karan

    The University of Toronto's Space Flight Laboratory operates the Canadian Advanced Nanospace eXperiment program in order to develop low-cost nanosatellites for education and research. Building of the laboratory's expertise in microsatellite system design, this unique program trains highly skilled space system engineers for the Canadian public and private sectors while producing low-cost, quick-to-launch satellite platforms for the scientific and engineering communities. Major projects completed through this program include the CanX-2 nanosatellite, which stands to be one of the most advanced in its class through sophistication and capability. Master's students at the Space Flight Laboratory channel their various backgrounds into highly qualified areas of expertise by developing key subsystems for CanX missions. This thesis will describe the development of the passive thermal control subsystem for CanX-2, and the preliminary design of the attitude determination and control subsystem for the CanX-3 astronomy mission and the CanX-4 & CanX-5 formation flight mission.

  7. Regulation of human lung fibroblast glycosaminoglycan production by recombinant interferons, tumor necrosis factor, and lymphotoxin.

    PubMed Central

    Elias, J A; Krol, R C; Freundlich, B; Sampson, P M

    1988-01-01

    Mononuclear cells may be important regulators of fibroblast glycosaminoglycan (GAG) biosynthesis. However, the soluble factors mediating these effects, the importance of intercytokine interactions in this regulation and the mechanisms of these alterations remain poorly understood. We analyzed the effect of recombinant (r) tumor necrosis factor (TNF), lymphotoxin (LT), and gamma, alpha, and beta 1 interferons (INF-gamma, -alpha and -beta 1), alone and in combination, on GAG production by normal human lung fibroblasts. rTNF, rLT, and rINF-gamma each stimulated fibroblast GAG production. In addition, rIFN-gamma synergized with rTNF and rLT to further augment GAG biosynthesis. In contrast, IFN-alpha A, -alpha D, and -beta 1 neither stimulated fibroblast GAG production nor interacted with rTNF or rLT to regulate GAG biosynthesis. The effects of the stimulatory cytokines and cytokine combinations were dose dependent and were abrogated by the respective monoclonal antibodies. In addition, these cytokines did not cause an alteration in the distribution of GAG between the fibroblast cell layer and supernatant. However, the stimulation was at least partially specific for particular GAG moieties with hyaluronic acid biosynthesis being markedly augmented without a comparable increase in the production of sulfated GAGs. Fibroblast prostaglandin production did not mediate these alterations since indomethacin did not decrease the stimulatory effects of the cytokines. In contrast, protein and mRNA synthesis appeared to play a role since the stimulatory effects of the cytokines were abrogated by cyclohexamide and actinomycin D, respectively. In addition, the cytokines and cytokine combinations increased cellular hyaluronate synthetase activity in proportion to their effects on hyaluronic acid suggesting that induction of this enzyme(s) is important in this stimulatory process. These studies demonstrate that IFN-gamma, TNF, and LT are important stimulators of fibroblast GAG

  8. Co-cultivation of Streptomyces californicus and Stachybotrys chartarum stimulates the production of cytostatic compound(s) with immunotoxic properties

    SciTech Connect

    Penttinen, Piia . E-mail: Piia.Penttinen@ktl.fi; Pelkonen, Jukka; Huttunen, Kati; Hirvonen, Maija-Riitta

    2006-12-15

    We have recently shown that the actinobacterium Streptomyces californicus and the fungus Stachybotrys chartarum originating from moisture damaged buildings possess both immunotoxic and immunostimulatory characteristics, which are synergistically potentiated by microbial interaction. In the search for the causative agent(s) behind the immunotoxicity, the cytostatic effects of the co-cultivated spores of S. californicus and S. chartarum were compared to those caused by widely used cytostatic agents produced by streptomycetes. The RAW264.7 macrophages were exposed to four doses of doxorubicin (DOX), actinomycin D (AMD), mitomycin C (MMC) or phleomycin (PHLEO) for 24 h. Kinetics of the spores of the co-cultivated and the separately cultivated microbes (1 x 10{sup 6} spores/ml) was compared to DOX (0.15 {mu}M). Apoptotic responses were analyzed by measuring DNA content and mitochondria membrane depolarization with flow cytometer, and by the fluorometric caspase-3 assay. The present data indicate that interactions during co-cultivation of S. californicus and S. chartarum stimulate the production of an unidentified cytostatic compound(s) capable of inducing mitochondria mediated apoptosis and cell cycle arrest at S-G{sub 2}/M. The spores of co-cultivated microbes caused a 4-fold collapse of mitochondrial membrane potential and an almost 6-fold caspase-3 activation and DNA fragmentation when compared to control. Similar responses were induced by DNA cleaving compounds, especially DOX and AMD, at the relatively low concentrations, but not the spores of the same microbes when they were grown separately. These data suggest that when growing in the same habitat, interactions between S. californicus and S. chartarum stimulates the production of an unknown cytostatic compound(s) which evoke immunotoxic effects similar to those by chemotherapeutic drugs.

  9. Measles virus C protein impairs production of defective copyback double-stranded viral RNA and activation of protein kinase R.

    PubMed

    Pfaller, Christian K; Radeke, Monte J; Cattaneo, Roberto; Samuel, Charles E

    2014-01-01

    Measles virus (MV) lacking expression of C protein (C(KO)) is a potent activator of the double-stranded RNA (dsRNA)-dependent protein kinase (PKR), whereas the isogenic parental virus expressing C protein is not. Here, we demonstrate that significant amounts of dsRNA accumulate during C(KO) mutant infection but not following parental virus infection. dsRNA accumulated during late stages of infection and localized with virus replication sites containing N and P proteins. PKR autophosphorylation and stress granule formation correlated with the timing of dsRNA appearance. Phospho-PKR localized to dsRNA-containing structures as revealed by immunofluorescence. Production of dsRNA was sensitive to cycloheximide but resistant to actinomycin D, suggesting that dsRNA is a viral product. Quantitative PCR (qPCR) analyses revealed reduced viral RNA synthesis and a steepened transcription gradient in C(KO) virus-infected cells compared to those in parental virus-infected cells. The observed alterations were further reflected in lower viral protein expression levels and reduced C(KO) virus infectious yield. RNA deep sequencing confirmed the viral RNA expression profile differences seen by qPCR between C(KO) mutant and parental viruses. After one subsequent passage of the C(KO) virus, defective interfering RNA (DI-RNA) with a duplex structure was obtained that was not seen with the parental virus. We conclude that in the absence of C protein, the amount of PKR activator RNA, including DI-RNA, is increased, thereby triggering innate immune responses leading to impaired MV growth. PMID:24155404

  10. Mild hydrothermal synthesis, crystal structure, spectroscopic and magnetic properties of the [M{sub x}{sup II}M{sub 2.5-x}{sup III}(H{sub 2}O){sub 2}(HP{sup III}O{sub 3}){sub y}(P{sup V}O{sub 4}){sub 2-y}F; M=Fe, x=2.08, y=1.58; M=Co, Ni, x=2.5, y=2] compounds

    SciTech Connect

    Orive, Joseba

    2009-08-15

    The [M{sub x}{sup II}M{sub 2.5-x}{sup III}(H{sub 2}O){sub 2}(HP{sup III}O{sub 3}){sub y}(P{sup V}O{sub 4}){sub 2-y}F; M=Fe (1), x=2.08, y=1.58; M=Co (2), x=2.5, y=2; Ni (3), x=2.5, y=2] compounds have been synthesized using mild hydrothermal conditions at 170 deg. C during five days. Single-crystals of (1) and (2), and polycrystalline sample of (3) were obtained. These isostructural compounds crystallize in the orthorhombic system, space group Aba2, with a=9.9598(2), b=18.8149(4) and c=8.5751(2) A for (1), a=9.9142(7), b=18.570(1) and c=8.4920(5) A for (2) and a=9.8038(2), b=18.2453(2) and c=8.4106(1) A for (3), with Z=8 in the three phases. An X-ray diffraction study reveals that the crystal structure is composed of a three-dimensional skeleton formed by [MO{sub 5}F] and [MO{sub 4}F{sub 2}] (M=Fe, Co and Ni) octahedra and [HPO{sub 3}] tetrahedra, partially substituted by [PO{sub 4}] tetrahedra in phase (1). The IR spectra show the vibrational modes of the water molecules and those of the (HPO{sub 3}){sup 2-} tetrahedral oxoanions. The thermal study indicates that the limit of thermal stability of these phases is 195 deg. C for (1) and 315 deg. C for (2) and (3). The electronic absorption spectroscopy shows the characteristic bands of the Fe(II), Co(II) and Ni(II) high-spin cations in slightly distorted octahedral geometry. Magnetic measurements indicate the existence of global antiferromagnetic interactions between the metallic centers with a ferromagnetic transition in the three compounds at 28, 14 and 21 K for (1), (2) and (3), respectively. Compound (1) exhibits a hysteresis loop with remnant magnetization and coercive field values of 0.72 emu/mol and 880 Oe, respectively. - Abstract: Polyhedral view of the crystal structure of the [M{sub x}{sup II}M{sub 2.5-x}{sup III}(H{sub 2}O){sub 2}(HP{sup III}O{sub 3}){sub y}(P{sup IV}O{sub 4}){sub 2-y}F; M=Fe, x=2.08, y=1.58; M=Co, Ni, x=2.5, y=2] compounds showing the sheets along the [001] direction.

  11. Studies on Phytoalexins

    PubMed Central

    Biggs, D. R.

    1972-01-01

    Actinomycin D stimulated phaseollin production in endocarp tissues of the French bean (Phaseolus vulgaris L.), maximum production being obtained with 25 to 30 micrograms per milliliter of antibiotic. Under these conditions, net incorporation of 3H-uridine into total cell ribonucleic acid was inhibited by more than 80% over a 6-hour induction period. If allowance was made for a 2-hour lag in the action of actinomycin D, inhibition of incorporation was greater than 95%. Contrary to other reports, no evidence was obtained of an increased formation of any specific ribonucleic acid fraction. Actinomycin D applied in the cold (4 C) was not found to be effective in stimulating phaseollin production. When applied in this way, actinomycin D did not affect induction of phaseollin by a fungal peptide, Monilicolin A, although ribonucleic acid synthesis was inhibited by more than 95%. It is suggested that the induced formation of phytoalexins may not be dependent on increased ribonucleic acid synthesis as has previously been claimed. Other experiments indicated that the apparent effects of actinomycin D on ribonucleic acid synthesis could be influenced by the choice of precursor used to label ribonucleic acid and by the order of addition of precursor and antibiotic to the plant tissue. These effects were only observed in the period immediately following application of actinomycin D. It is suggested that such effects could critically influence the results obtained in short term experiments and may explain some differences in reported action of actinomycin D from different laboratories. PMID:16658238

  12. Effect of Post-Weld Heat Treatment on Mechanical and Electrochemical Properties of Gas Metal Arc-Welded 316L (X2CrNiMo 17-13-2) Stainless Steel

    NASA Astrophysics Data System (ADS)

    Muhammad, F.; Ahmad, A.; Farooq, A.; Haider, W.

    2016-08-01

    In the present research work, corrosion behavior of post-weld heat-treated (PWHT) AISI 316L (X2CrNiMo 17-13-2) specimens joined by gas metal arc welding is compared with as-welded samples by using potentiodynamic polarization technique. Welded samples were PWHT at 1323 K for 480 s and quenched. Mechanical properties, corrosion behavior and microstructures of as-welded and PWHT specimens were investigated. Microstructural studies have shown grain size refinement after PWHT. Ultimate tensile strength and yield strength were found maximum for PWHT samples. Bend test have shown that PWHT imparted ductility in welded sample. Fractographic analysis has evidenced ductile behavior for samples. Potentiodynamic polarization test was carried out in a solution composed of 1 M H2SO4 and 1 N NaCl. Corrosion rate of weld region was 127.6 mpy, but after PWHT, it was decreased to 13.12 mpy.

  13. Coexistence of superconductivity and a charge density wave in LaPt2(Si1-x Ge x )2 (0 ⩽ x ⩽ 0.5).

    PubMed

    Gupta, Ritu; Paramanik, U B; Ramakrishnan, S; Rajeev, K P; Hossain, Z

    2016-05-18

    Interplay between a charge density wave (CDW) and superconductivity in LaPt2(Si1-x Ge x )2 has been studied by electrical transport and magnetic measurements. LaPt2Si2 crystallizes in CaBe2Ge2 type structure which shows a first order structural phase transition from tetragonal to orthorhombic accompanied by a CDW transition at 112 K and superconducting transition at around 1.22 K as confirmed by temperature dependence of resistivity and magnetic measurements. For 2[Formula: see text] doping of germanium, while the CDW temperature T CDW decreases, the superconducting transition temperature T C shows an increase. T CDW increases for 5[Formula: see text] doping of germanium and the superconducting transition decreases. These findings demonstrate the competing nature of a CDW and superconductivity.

  14. Cumberland and Pittsburgh 1/sup 0/ x 2/sup 0/ NTMS areas Maryland, Pennsylvania, Virginia, and West Virginia: data report (abbreviated). National uranium resource evaluation program, hydrogeochemical and stream sediment reconnaissance

    SciTech Connect

    Fay, W.M.

    1981-07-01

    This report summarizes results of ground water, surface water, and stream sediment reconnaissance in the National Topographic Map Series (NTMS) Cumberland and Pittsburgh 1/sup 0/ x 2/sup 0/ NTMS quadrangles. Surface sediment samples were collected at 1042 sites in the Cumberland quadrangle and 342 sites in the Pittsburgh quadrangle. Ground water samples were collected at 1240 sites in the Cumberland quadrangle and 467 sites in the Pittsburgh quadrangle. Neutron activation analysis results are given for uranium and 16 other elements in sediments, for uranium and 8 other elements in ground water, and for uranium and 9 other elements in surface water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps.

  15. Field-induced pinning effect of Nd(Ba 1- xNd x) 2Cu 3O 7-δ single crystals grown by the traveling-solvent floating-zone method

    NASA Astrophysics Data System (ADS)

    Egi, T.; Wen, J. G.; Kuroda, K.; Mori, H.; Unoki, H.; Koshizuka, N.

    1996-02-01

    We have studied the superconducting properties of Nd(Ba 1- xNd x) 2Cu 3O 7-δ (Nd123, x ≈ 0.1) single crystals grown by the traveling-solvent floating-zone method under 0.1% O 2 in Ar atmosphere. The enhancement of the magnetization with increasing field is observed in the hysteresis ( M- H) loop in fields both parallel and perpendicular to the c-axis of the Nd123 single crystals as well as in the bulk crystals prepared by the oxygen-controlled-melt-growth (OCMG) method. The composition variation of Ba/Nd is observed in the matrix of Nd123 crystals by an analytical TEM equipped with a cold field-emission gun. It turns out that the enhancement is due to the field-induced pinning effect ascribed to the weak superconducting NdBa substitution regions in the Nd123 matrix.

  16. Rotational level-dependent collisional broadening and line shift of the A2Sigma(+)-X2Pi (1,0) band of OH in hydrogen-air combustion gases

    NASA Technical Reports Server (NTRS)

    Kessler, W. J.; Allen, M. G.; Davis, S. J.

    1993-01-01

    Measurements of the collisional broadening and line shift of the (1,0) band of the A2Sigma(+)-X2Pi system of OH are reported in atmospheric pressure hydrogen-air combustion gases. The measurements were made using a single-mode, narrow linewidth, frequency-doubled ring dye laser operating near 283 nm. The OH was generated in the combustion gases of a flat flame H2-air burner. Collisional broadening parameters for equilibrium mixtures of H2, O2, H2O, and N2 were obtained spanning a range of fuel/air equivalence ratios from 0.6 to 1.6 and temperatures from 1500 to 2050 K. Measurements were obtained spanning rotational quantum numbers from 4.5 to 16.5. The collision induced frequency shift was determined to be 0.1 that of the collisional broadening.

  17. Coexistence of superconductivity and a charge density wave in LaPt2(Si1-x Ge x )2 (0 ⩽ x ⩽ 0.5).

    PubMed

    Gupta, Ritu; Paramanik, U B; Ramakrishnan, S; Rajeev, K P; Hossain, Z

    2016-05-18

    Interplay between a charge density wave (CDW) and superconductivity in LaPt2(Si1-x Ge x )2 has been studied by electrical transport and magnetic measurements. LaPt2Si2 crystallizes in CaBe2Ge2 type structure which shows a first order structural phase transition from tetragonal to orthorhombic accompanied by a CDW transition at 112 K and superconducting transition at around 1.22 K as confirmed by temperature dependence of resistivity and magnetic measurements. For 2[Formula: see text] doping of germanium, while the CDW temperature T CDW decreases, the superconducting transition temperature T C shows an increase. T CDW increases for 5[Formula: see text] doping of germanium and the superconducting transition decreases. These findings demonstrate the competing nature of a CDW and superconductivity. PMID:27094445

  18. Effect of Post-Weld Heat Treatment on Mechanical and Electrochemical Properties of Gas Metal Arc-Welded 316L (X2CrNiMo 17-13-2) Stainless Steel

    NASA Astrophysics Data System (ADS)

    Muhammad, F.; Ahmad, A.; Farooq, A.; Haider, W.

    2016-10-01

    In the present research work, corrosion behavior of post-weld heat-treated (PWHT) AISI 316L (X2CrNiMo 17-13-2) specimens joined by gas metal arc welding is compared with as-welded samples by using potentiodynamic polarization technique. Welded samples were PWHT at 1323 K for 480 s and quenched. Mechanical properties, corrosion behavior and microstructures of as-welded and PWHT specimens were investigated. Microstructural studies have shown grain size refinement after PWHT. Ultimate tensile strength and yield strength were found maximum for PWHT samples. Bend test have shown that PWHT imparted ductility in welded sample. Fractographic analysis has evidenced ductile behavior for samples. Potentiodynamic polarization test was carried out in a solution composed of 1 M H2SO4 and 1 N NaCl. Corrosion rate of weld region was 127.6 mpy, but after PWHT, it was decreased to 13.12 mpy.

  19. A crossed molecular beam and ab initio investigation of the exclusive methyl loss pathway in the gas phase reaction of boron monoxide (BO; X2Σ+) with dimethylacetylene (CH3CCCH3; X1A(1g)).

    PubMed

    Kaiser, Ralf I; Maity, Surajit; Dangi, Beni B; Su, Yuan-Siang; Sun, B J; Chang, Agnes H H

    2014-01-21

    The crossed molecular beam reaction of boron monoxide ((11)BO; X(2)Σ(+)) with dimethylacetylene (CH3CCCH3; X(1)A(1g)) was investigated at a collision energy of 23.9 ± 1.5 kJ mol(-1). The scattering dynamics were suggested to be indirect (complex forming reaction) and were initiated by the addition of (11)BO(X(2)Σ(+)) with the radical center located at the boron atom to the π electron density at the acetylenic carbon-carbon triple bond without entrance barrier leading to cis-trans(11)BOC4H6 doublet radical intermediates. cis-(11)BOC4H6 underwent cis-trans isomerization followed by unimolecular decomposition via a methyl group (CH3) loss forming 1-propynyl boron monoxide (CH3CC(11)BO) in an overall exoergic reaction (experimental: -91 ± 22 kJ mol(-1); theoretical: -105 ± 9 kJ mol(-1); NIST: -104 ± 12 kJ mol(-1)) via a tight exit transition state; trans-(11)BOC4H6 was found to lose a methyl group instantaneously. Neither atomic nor molecular hydrogen loss pathways were detectable. The experimental finding of an exclusive methyl loss pathway gains full support from our computational study predicting a methyl group versus atomic hydrogen loss branching ratio of 99.99% to 0.01% forming 1-propynyl boron monoxide (CH3CC(11)BO) and 1-methyl-propadienyl boron monoxide (CH3((11)BO)CCCH2), respectively. PMID:24281672

  20. Synthesis, crystal structure and characterization of new 12H hexagonal perovskite-related oxides Ba 6M2Na 2X2O 17 ( M=Ru, Nb, Ta, Sb; X=V, Cr, Mn, P, As)

    NASA Astrophysics Data System (ADS)

    Quarez, Eric; Abraham, Francis; Mentré, Olivier

    2003-11-01

    The new Ba 6Ru 2Na 2X2O 17 ( X=V, Mn) compounds have been prepared by electrosynthesis in molten NaOH and their crystal structures have been refined from single crystals X-ray diffraction, space group P6 3/ mmc, Z=2, for X=V: a =5.8506(1) Å, c =29.6241(4) Å, R1=4.76%, for X=Mn : a =5.8323(1) Å, c =29.5299(3) Å, R1=3.48%. The crystal structure is a 12H-type perovskite with a ( c' cchcc) 2 stacking sequence of [BaO 3] c, [BaO 3] h and [BaO 2] c' layers. The tridimensional edifice is formed by blocks of Ru 2O 9 dimers that share corners with NaO 6 octahedra. These blocks sandwich double sheets of X5+O 4 tetrahedra. Several isotypic Ba 6M5+2Na 2X5+2O 17 materials ( X=V, Cr, Mn, P, As) and ( M=Ru, Nb, Ta, Sb) have been prepared by solid state reaction and characterized by Rietveld analysis. The magnetic and electric properties have been investigated and show besides the Ru 5+2O 9 typical intradimer antiferromagnetic couplings, discrepancies of both χ and ρ versus T at 50 and 100 K for Ba 6Ru 2Na 2X2O 17 ( X=V, As). In this work, a review of the identified Ru-hexagonal perovskite materials is also reported in order to overview the wide variety of possibilities in the field of new compounds synthesis.

  1. Ternary lanthanum sulfide selenides {alpha}-LaS{sub 2-x}Se{sub x} (0<x<2) with mixed dichalcogenide anions X{sub 2}{sup 2-} (X=S, Se)

    SciTech Connect

    Bartsch, Christian; Doert, Thomas

    2012-01-15

    Mixed lanthanum sulfide selenides LaS{sub 2-x}Se{sub x} (0<x<2) were obtained by metathesis reactions starting from anhydrous lanthanum chloride and alkali metal polychalcogenides. The LaS{sub 2-x}Se{sub x} compounds crystallize in space group P2{sub 1}/a, no. 14, and adopt the {alpha}-LnS{sub 2} (Ln=Y, La-Lu) structure type with a pronounced site preference for the chalcogen atoms. The mixed chalcogenides form a complete miscible series with lattice parameters a=820-849 pm, b=413-425 pm and c=822-857 pm ({beta} Almost-Equal-To 90 Degree-Sign) following Vegard's rule. Raman signals indicate the presence of mixed X{sub 2}{sup 2-} dianions, a species rarely evidenced in literature, besides the well known anions S{sub 2}{sup 2-} and Se{sub 2}{sup 2-}. The band gaps of the LaS{sub 2-x}Se{sub x} compounds, determined by optical spectroscopy, decrease nearly linearly with increasing amount of selenium. - Graphical abstract: Raman spectra and site occupancies in the structures of selected lanthanum sulfide selenides. Highlights: Black-Right-Pointing-Pointer Vegard series of mixed lanthanum sulfide selenides LaS{sub 2-x}Se{sub x} (0<x<2). Black-Right-Pointing-Pointer Pronounced site ordering of chalcogen positions. Black-Right-Pointing-Pointer Optical band gaps decrease with Se content. Black-Right-Pointing-Pointer Raman measurements evidence mixed X{sub 2}{sup 2-} dimeric anions.

  2. Far-wing excitation study of the reactions in the Hg-H2 collisional quasimolecules. II. Rovibrational distributions of HgH, HgD (X 2Sigma + ) formed from Hg-H2, D2, HD

    NASA Astrophysics Data System (ADS)

    Ohmori, K.; Takahashi, T.; Chiba, H.; Saito, K.; Nakamura, T.; Okunishi, M.; Ueda, K.; Sato, Y.

    1996-11-01

    We have applied the laser-pump/probe and double-beam absorption/dispersion approaches to the far wings of the Hg 3P1-1S0 resonance line broadened by collisions with H2, D2, and HD. Absolute reduced absorption coefficients of the Hg-D2 quasimolecules have been determined as a function of the wave-number shift Δ from the resonance-line center both in the red and blue wings. The nascent rotational distributions have been determined for the v=0 and 1 levels of HgH (X 2Σ+) and the v=0 level of HgD (X 2Σ+) formed from the Hg*(3P1)-H2, D2, and HD collisional-quasimolecular states à and B˜ attained by the red- and blue-wing excitation, respectively. Both of the intermediate states à and B˜ give quite similar rotational distributions peaking around N≂18 for HgH and N≂25 for HgD insensitive to the excitation-wave-number shift Δ. However, a small difference is found: the red-wing excitation gives larger populations in the low-N levels than the blue-wing one. The departing atom isotope effect is observed in these low-N populations of HgD from Hg-D2 and Hg-HD. The absolute ratio of the nascent yields of v=1 to 0 has been measured to be 0.3, being nearly constant against Δ in both the red and blue wings. These observations indicate that HgH is formed predominantly from a bent H-Hg-H configuration on both the pathways via the à and B˜ states. The different type of transition state, however, may be encountered on the pathways producing the minor components in the low-N levels.

  3. Influences of the substituents on the M-M bonding in Cp4Al4 and Cp2M2X2 (M = B, Al, Ga; Cp = C5H5, X = halogen).

    PubMed

    Lu, Feifei; Li, Xiaoyan; Sun, Zheng; Zeng, Yanli; Meng, Lingpeng

    2015-08-21

    Although the geometries of CpAl4 (Cp* = C5Me5) and Cp4Al4 (Cp = C5H5) are similar, CpAl4 is more stable than Cp4Al4. CpAl2I2 is the first complex involving an Al(ii)-Al(ii) bond to be supported by Cp-type ligands. In this work, the stability of CpAl4 and Cp4Al4 (Cp = C5H5), the nature of M-M bonding in Cp2M2X2 (M = B, Al, and Ga), and the influences of the X atom on the M-M bonds have been analyzed and compared within the framework of the atoms in molecules (AIM) theory, electron localization function (ELF), energy decomposition analysis (EDA), and natural bond orbital (NBO) analysis. The calculated results show that CpAl4 is more stable than Cp4Al4 because of HH interactions between the methyl groups on the same and different Cp rings and not because of the Al-Al bonds. In Cp2M2X2, the B-B bond is stronger than the Al-Al and Ga-Ga bonds. The B-B bond is most consistent with covalent bonding, whereas the Al-Al and Ga-Ga bonds are more consistent with metallic bonding. The strengths of the B-B bond increase in the sequence X = F, Cl, Br, and I, whereas the Al-Al and Ga-Ga bonds decrease in the sequence X = F, Cl, Br, and I. The different change tendencies arise from the different M-M bonds and the orbital interactions between atoms X and M.

  4. A crossed molecular beam and ab initio investigation of the exclusive methyl loss pathway in the gas phase reaction of boron monoxide (BO; X2Σ+) with dimethylacetylene (CH3CCCH3; X1A(1g)).

    PubMed

    Kaiser, Ralf I; Maity, Surajit; Dangi, Beni B; Su, Yuan-Siang; Sun, B J; Chang, Agnes H H

    2014-01-21

    The crossed molecular beam reaction of boron monoxide ((11)BO; X(2)Σ(+)) with dimethylacetylene (CH3CCCH3; X(1)A(1g)) was investigated at a collision energy of 23.9 ± 1.5 kJ mol(-1). The scattering dynamics were suggested to be indirect (complex forming reaction) and were initiated by the addition of (11)BO(X(2)Σ(+)) with the radical center located at the boron atom to the π electron density at the acetylenic carbon-carbon triple bond without entrance barrier leading to cis-trans(11)BOC4H6 doublet radical intermediates. cis-(11)BOC4H6 underwent cis-trans isomerization followed by unimolecular decomposition via a methyl group (CH3) loss forming 1-propynyl boron monoxide (CH3CC(11)BO) in an overall exoergic reaction (experimental: -91 ± 22 kJ mol(-1); theoretical: -105 ± 9 kJ mol(-1); NIST: -104 ± 12 kJ mol(-1)) via a tight exit transition state; trans-(11)BOC4H6 was found to lose a methyl group instantaneously. Neither atomic nor molecular hydrogen loss pathways were detectable. The experimental finding of an exclusive methyl loss pathway gains full support from our computational study predicting a methyl group versus atomic hydrogen loss branching ratio of 99.99% to 0.01% forming 1-propynyl boron monoxide (CH3CC(11)BO) and 1-methyl-propadienyl boron monoxide (CH3((11)BO)CCCH2), respectively.

  5. Future Avionics for X2K

    NASA Technical Reports Server (NTRS)

    Karmon, D.; Chau, S.

    1999-01-01

    The JPL X2000 program is for the delivery of advanced avionics systems, cutting edge technologies, and avionics components to spacecraft/orbiter, micro/nano-spacecraft, and in-situ missions. The objective is to develop and deliver avionics systems that will serve a multitude of future missions over the next 12 to 15 years.

  6. Agreement among 2 x 2 Agreement Indices.

    ERIC Educational Resources Information Center

    Conger, Anthony J.; Ward, David G.

    1984-01-01

    Sixteen measures of reliability for two-category nominal scales are compared. Upon correcting for chance agreement, there are only five distinct indices: Fleiss's modification of A-sub-1, the phi coefficient, Cohen's kappa, and two intraclass coefficients. Recommendations for choosing an agreement index are made based on definitions, magnitude,…

  7. Antihydrogen production

    SciTech Connect

    Rizzini, Evandro Lodi; Venturelli, Luca; Zurlo, Nicola

    2008-08-08

    Antihydrogen production in ATHENA is analyzed more carefully. The most important peculiarities of the different experimental situations are discussed. The protonium production via the first matter-antimatter chemical reaction is commented too.

  8. Docosahexanoic acid antagonizes TNF-α-induced necroptosis by attenuating oxidative stress, ceramide production, lysosomal dysfunction, and autophagic features

    PubMed Central

    Pacheco, Fabio J.; Almaguel, Frankis G.; Evans, Whitney; Rios-Colon, Leslimar; Filippov, Valery; Leoh, Lai S.; Rook-Arena, Elizabeth; Mediavilla-Varela, Melanie; De Leon, Marino

    2014-01-01

    Objective It was previously reported that docosahexanoic acid (DHA) reduces TNF-α-induced necrosis in L929 cells. However, the mechanisms underlying this reduction have not been investigated. The present study was designed to investigate cellular and biochemical mechanisms underlying the attenuation of TNF-α-induced necroptosis by DHA in L929 cells. Methods L929 cells were pre-treated with DHA prior to exposure to TNF-α, zVAD, or Necrostatin-1 (Nec-1). Cell death and survival were assessed by MTT and caspase activity assays, and microscopic visualization. Reactive oxygen species (ROS) were measured by flow cytometry. C16- and C18-ceramide were measured by mass spectrometry. Lysosomal membrane permeabilization (LMP) was evaluated by fluorescence microscopy and flow cytometry using Acridine Orange. Cathepsin L activation was evaluated by immunoblotting and fluorescence microscopy. Autophagy was assessed by immunoblotting of LC3-II and Beclin. Results Exposure of L929 cells to TNF-α alone for 24 h induced necroptosis, as evidenced by inhibition of cell death by Nec-1, absence of caspase-3 activity and lamin B cleavage, and morphological analysis. DHA attenuated multiple biochemical events associated with TNF-α-induced necroptosis, including ROS generation, ceramide production, lysosomal dysfunction, cathepsin L activation, and autophagic features. DHA also attenuated zVAD-induced necroptosis but did not attenuate the enhanced apoptosis and necrosis induced by combination of TNF-α with Actinomycin D or zVAD, respectively, suggesting that its protective effects might be limited by the strength of the cell death insult induced by TNF-α. Conclusions DHA effectively attenuates TNF-α-induced necroptosis and autophagy, most likely via its ability to inhibit TNF-α-induced sphingolipid metabolism and oxidative stress. These results highlight the role of this Omega-3 fatty acid in antagonizing inflammatory cell death. PMID:25095742

  9. Rovibrationally selected ion-molecule collision study using the molecular beam vacuum ultraviolet laser pulsed field ionization-photoion method: Charge transfer reaction of N2+(X 2Σg+; v+ = 0-2; N+ = 0-9) + Ar

    NASA Astrophysics Data System (ADS)

    Chang, Yih Chung; Xu, Yuntao; Lu, Zhou; Xu, Hong; Ng, C. Y.

    2012-09-01

    We have developed an ion-molecule reaction apparatus for state-selected absolute total cross section measurements by implementing a high-resolution molecular beam vacuum ultraviolet (VUV) laser pulsed field ionization-photoion (PFI-PI) ion source to a double-quadrupole double-octopole ion-guide mass spectrometer. Using the total cross section measurement of the state-selected N2+(v+, N+) + Ar charge transfer (CT) reaction as an example, we describe in detail the design of the VUV laser PFI-PI ion source used, which has made possible the preparation of reactant N2+(X 2Σg+, v+ = 0-2, N+ = 0-9) PFI-PIs with high quantum state purity, high intensity, and high kinetic energy resolution. The PFI-PIs and prompt ions produced in the ion source are shown to have different kinetic energies, allowing the clean rejection of prompt ions from the PFI-PI beam by applying a retarding potential barrier upstream of the PFI-PI source. By optimizing the width and amplitude of the pulsed electric fields employed to the VUV-PFI-PI source, we show that the reactant N2+ PFI-PI beam can be formed with a laboratory kinetic energy resolution of ΔElab = ± 50 meV. As a result, the total cross section measurement can be conducted at center-of-mass kinetic energies (Ecm's) down to thermal energies. Absolute total rovibrationally selected cross sections σ(v+ = 0-2, N+ = 0-9) for the N2+(X 2Σg+; v+ = 0-2, N+ = 0-9) + Ar CT reaction have been measured in the Ecm range of 0.04-10.0 eV, revealing strong vibrational enhancements and Ecm-dependencies of σ(v+ = 0-2, N+ = 0-9). The thermochemical threshold at Ecm = 0.179 eV for the formation of Ar+ from N2+(X; v+ = 0, N+) + Ar was observed by the measured σ(v+ = 0), confirming the narrow ΔEcm spread achieved in the present study. The σ(v+ = 0-2; N+) values obtained here are compared with previous experimental and theoretical results. The theoretical predictions calculated based on the Landau-Zener-Stückelberg formulism are found to be in fair

  10. Ab initio studies of the interaction potential for the Xe-NO(X2Π) van der Waals complex: bound states and fully quantum and quasi-classical scattering.

    PubMed

    Kłos, J; Aoiz, F J; Menéndez, M; Brouard, M; Chadwick, H; Eyles, C J

    2012-07-01

    Adiabatic potential energy surfaces for the ground electronic state of the Xe⋅⋅⋅NO(X(2)Π) van der Waals complex have been calculated using the spin-restricted coupled cluster method with single, double, and non-iterative triple excitations (RCCSD(T)). The scalar relativistic effects present in the Xe atom were included by an effective core potential and we extended the basis with bond functions to improve the description of the dispersion interaction. It has been found that the global minimum on the A(') adiabatic surface occurs at a T-shaped geometry with γ(e) = 94° and R(e) = 7.46 a(0), and with well depth of D(e) = 148.68 cm(-1). There is also an additional local minimum for the collinear geometry Xe-NO with a well depth of 104.5 cm(-1). The adiabat of A('') symmetry exhibits a single minimum at a distance R(e) = 7.68 a(0) and has a skewed geometry with γ(e) = 64° and a well depth of 148.23 cm(-1). Several C(nl) van der Waals dispersion coefficients are also estimated, of which C(6, 0) and C(6, 2) are in a reasonable agreement with previous theoretical results obtained by Nielson et al. [J. Chem. Phys. 64, 2055 (1976)]. The new potential energy surfaces were used to calculate bound states of the complex for total angular momentum quantum numbers up to J = 7/2. The ground state energy of Xe⋅⋅⋅NO(X(2)Π) is D(0) = 117 cm(-1), which matches the experimental value very accurately (within 3.3%). Scattering calculations of integral and differential cross sections have also been performed using fully quantum close coupling calculations and quasi-classical trajectory method at a collision energy of 63 meV. These calculations reveal the important role played by L-type rainbows in the scattering dynamics of the heavier Rg-NO(X) systems.

  11. Analysis of the Rotationally Resolved, Non-Degenerate (a''_1) and Degenerate (e') Vibronic Bands in the tilde{A}^2E'' ← tilde{X}^2A'_2 Transition of NO_3.

    NASA Astrophysics Data System (ADS)

    Tran, Henry; Miller, Terry A.

    2016-06-01

    The magnitude of the Jahn-Teller (JT) effect in NO_3 has been the subject of considerable research in our group and other groups around the world. The rotational contour of the 4^1_0 vibronic band was first described by Hirota and coworkers using an oblate symmetric top. Near-infrared band of the nitrate radical NO_3 observed by diode laser spectroscopy. J. Chem. Phys., 107:2829, 1997.} Deev et al. argued that an asymmetric top was required to describe the 2^1_0 band, although their spectrum was not completely rotationally resolved. These discrepancies suggest that a rotational analysis will provide considerable experimental information on the geometry of NO_3. Our group has collected high-resolution, rotationally resolved spectra of the vibronic tilde{A}^2E'' ← tilde{X}^2A'_2 transitions. We have completed analysis of the 3^1_0 and 3^1_04^1_0 parallel bands with a_1'' symmetry by using an oblate symmetric top with spin-rotation and centrifugal distortions. Several other parallel bands are now also reasonably understood. This analysis is consistent with a D3h geometry for NO_3. In order to analyze the perpendicular bands with e' symmetry, we have adapted the oblate symmetric top Hamiltonian from the previous analysis to include spin-orbit coupling, coriolis coupling, and Watson Terms (JT distortions) that allow the oblate symmetric top Hamiltonian to transition continuously to the distorted limit of C2v symmetry. Preliminary analysis of the 2^1_0 and 2^1_04^2_0 bands has shown generally good agreement between model and experimental spectra. Our results indicate only modest JT distortions, although we do find evidence of multiple perturbations between these bands and high vibrational levels of the tilde{X} state. We will present our adapted Hamiltonian and the analysis of the 3^1_0, 3^1_04^1_0, 2^1_0, and 2^1_04^2_0 bands. E. Hirota, T. Ishiwata, K. Kawaguchi, M. Fujitake, N. Ohashi, and I. Tanaka. Near-infrared band of the nitrate radical NO_3 observed by diode

  12. Ab initio studies of the interaction potential for the Xe-NO(X2Π) van der Waals complex: bound states and fully quantum and quasi-classical scattering.

    PubMed

    Kłos, J; Aoiz, F J; Menéndez, M; Brouard, M; Chadwick, H; Eyles, C J

    2012-07-01

    Adiabatic potential energy surfaces for the ground electronic state of the Xe⋅⋅⋅NO(X(2)Π) van der Waals complex have been calculated using the spin-restricted coupled cluster method with single, double, and non-iterative triple excitations (RCCSD(T)). The scalar relativistic effects present in the Xe atom were included by an effective core potential and we extended the basis with bond functions to improve the description of the dispersion interaction. It has been found that the global minimum on the A(') adiabatic surface occurs at a T-shaped geometry with γ(e) = 94° and R(e) = 7.46 a(0), and with well depth of D(e) = 148.68 cm(-1). There is also an additional local minimum for the collinear geometry Xe-NO with a well depth of 104.5 cm(-1). The adiabat of A('') symmetry exhibits a single minimum at a distance R(e) = 7.68 a(0) and has a skewed geometry with γ(e) = 64° and a well depth of 148.23 cm(-1). Several C(nl) van der Waals dispersion coefficients are also estimated, of which C(6, 0) and C(6, 2) are in a reasonable agreement with previous theoretical results obtained by Nielson et al. [J. Chem. Phys. 64, 2055 (1976)]. The new potential energy surfaces were used to calculate bound states of the complex for total angular momentum quantum numbers up to J = 7/2. The ground state energy of Xe⋅⋅⋅NO(X(2)Π) is D(0) = 117 cm(-1), which matches the experimental value very accurately (within 3.3%). Scattering calculations of integral and differential cross sections have also been performed using fully quantum close coupling calculations and quasi-classical trajectory method at a collision energy of 63 meV. These calculations reveal the important role played by L-type rainbows in the scattering dynamics of the heavier Rg-NO(X) systems. PMID:22779653

  13. On integrable matrix product operators with bond dimension D = 4

    NASA Astrophysics Data System (ADS)

    Katsura, Hosho

    2015-01-01

    We construct and study a two-parameter family of matrix product operators of bond dimension D = 4. The operators M(x, y) act on ({\\Bbb{C}}_2)\\otimes N , i.e. the space of states of a spin-1/2 chain of length N. For the particular values of the parameters: x = 1/3 and y=1/\\sqrt{3} , the operator turns out to be proportional to the square root of the reduced density matrix of the valence-bond-solid state on a hexagonal ladder. We show that M(x, y) has several interesting properties when (x, y) lies on the unit circle centered at the origin: x2 + y2 = 1. In this case, we find that M(x, y) commutes with the Hamiltonian and all the conserved charges of the isotropic spin-1/2 Heisenberg chain. Moreover, M(x1, y1) and M(x2, y2) are mutually commuting if x^2i + y^2_i=1 for both i = 1 and 2. These remarkable properties of M(x, y) are proved as a consequence of the Yang-Baxter equation.

  14. Production facilities

    SciTech Connect

    Not Available

    1989-01-01

    This book presents a cross section of different solutions to the many unique production problems operators face. Sections address benefit vs. cost options for production facility designs, oil and gas separation processes and equipment, oil treating and desalting systems, and water treating methods and equipment. Papers were selected to give an overall view of factors involved in optimizing the design of cost-effective production facilities.

  15. Absolute Integral Cross Sections for the State-selected Ion-Molecule Reaction N2+(X2Σg+ v+ = 0-2) + C2H2 in the Collision Energy Range of 0.03-10.00 eV

    NASA Astrophysics Data System (ADS)

    Xu, Yuntao; Xiong, Bo; Chung Chang, Yih; Ng, C. Y.

    2016-08-01

    Using the vacuum ultraviolet laser pulsed field ionization-photoion source, together with the double-quadrupole-double-octopole mass spectrometer developed in our laboratory, we have investigated the state-selected ion-molecule reaction {{{{N}}}2}+({X}2{{{{Σ }}}{{g}}}+; v + = 0-2, N+ = 0-9) + C2H2, achieving high internal-state selectivity and high kinetic energy resolution for reactant {{{{N}}}2}+ ions. The charge transfer (CT) and hydrogen-atom transfer (HT) channels, which lead to the respective formation of product {{{C}}}2{{{{H}}}2}+ and N2H+ ions, are observed. The vibrationally selected absolute integral cross sections for the CT [σ CT(v +)] and HT [[σ HT(v +)] channels obtained in the center-of-mass collision energy (E cm) range of 0.03-10.00 eV reveal opposite E cm dependences. The σ CT(v +) is found to increase as E cm is decreased, and is consistent with the long-range exothermic CT mechanism, whereas the E cm enhancement observed for the σ HT(v +) suggests effective coupling of kinetic energy to internal energy, enhancing the formation of N2H+. The σ HT(v +) curve exhibits a step at E cm = 0.70-1.00 eV, suggesting the involvement of the excited {{{C}}}2{{{{H}}}2}+({A}2{{{{Σ }}}{{g}}}+) state in the HT reaction. Contrary to the strong E cm dependences for σ CT(v +) and σ HT(v +), the effect of vibrational excitation of {{{{N}}}2}+ on both the CT and HT channels is marginal. The branching ratios and cross sections for the CT and HT channels determined in the present study are useful for modeling the atmospheric compositions of Saturn's largest moon, Titan. These cross sections and branching ratios are also valuable for benchmarking theoretical calculations on chemical dynamics of the titled reaction.

  16. Absolute Integral Cross Sections for the State-selected Ion–Molecule Reaction N2+(X2Σg+ v+ = 0–2) + C2H2 in the Collision Energy Range of 0.03–10.00 eV

    NASA Astrophysics Data System (ADS)

    Xu, Yuntao; Xiong, Bo; Chung Chang, Yih; Ng, C. Y.

    2016-08-01

    Using the vacuum ultraviolet laser pulsed field ionization-photoion source, together with the double-quadrupole–double-octopole mass spectrometer developed in our laboratory, we have investigated the state-selected ion–molecule reaction {{{{N}}}2}+({X}2{{{{Σ }}}{{g}}}+; v + = 0–2, N+ = 0–9) + C2H2, achieving high internal-state selectivity and high kinetic energy resolution for reactant {{{{N}}}2}+ ions. The charge transfer (CT) and hydrogen-atom transfer (HT) channels, which lead to the respective formation of product {{{C}}}2{{{{H}}}2}+ and N2H+ ions, are observed. The vibrationally selected absolute integral cross sections for the CT [σ CT(v +)] and HT [[σ HT(v +)] channels obtained in the center-of-mass collision energy (E cm) range of 0.03–10.00 eV reveal opposite E cm dependences. The σ CT(v +) is found to increase as E cm is decreased, and is consistent with the long-range exothermic CT mechanism, whereas the E cm enhancement observed for the σ HT(v +) suggests effective coupling of kinetic energy to internal energy, enhancing the formation of N2H+. The σ HT(v +) curve exhibits a step at E cm = 0.70–1.00 eV, suggesting the involvement of the excited {{{C}}}2{{{{H}}}2}+({A}2{{{{Σ }}}{{g}}}+) state in the HT reaction. Contrary to the strong E cm dependences for σ CT(v +) and σ HT(v +), the effect of vibrational excitation of {{{{N}}}2}+ on both the CT and HT channels is marginal. The branching ratios and cross sections for the CT and HT channels determined in the present study are useful for modeling the atmospheric compositions of Saturn's largest moon, Titan. These cross sections and branching ratios are also valuable for benchmarking theoretical calculations on chemical dynamics of the titled reaction.

  17. COSMO-RS analysis on mixing properties obtained for the systems 1-butyl-X-methylpyridinium tetrafluoroborate [X = 2,3,4] and 1,ω-dibromoalkanes [ω = 1-6].

    PubMed

    Navas, Ana; Ortega, Juan; Palomar, José; Díaz, Carlos; Vreekamp, Remko

    2011-05-01

    A theoretical-experimental study for a set of 18 binary systems comprised of [bXmpy][BF(4)] (X=2-4) + 1,ω-Br(CH(2))(v)Br (v =ω=1-6) at a temperature of 298.15 K is presented. The solubility curves are determined for each binary system, establishing the intervals of measurement for the excess properties, H(E)(m) and V(E)(m). These properties are then determined for those systems that present a miscibility zone. Binary systems containing 1,ω-dibromoalkanes with ω=5,6 present reduced solubility intervals at the temperature of 298.15 K. However, the mixtures with 1,1-dibromomethane were totally miscible with the three isomers of 1-butyl-X-methylpyridinium tetrafluoroborate. Mixtures with dibromomethane present H(E)(m) <0, whereas H(E)(m) >0 for the other binary systems. Sigmoidal curves were observed for the V(E)(m) describing expansion and contraction processes for all the systems, except for the mixtures of [b2mpy][BF(4)] with the smaller dibromoalkanes, which present contraction effects. The COSMO-RS methodology was used to estimate the solubilities and the intermolecular interaction energies, giving an acceptable explanation of the behavioral structure of pure compounds and solutions. PMID:21437322

  18. New insights into the comprehension of the magnetic properties of dinuclear Mn(III) compounds with the general formula [{MnL(NN)}2(μ-O)(μ-n-RC6H4COO)2]X2.

    PubMed

    Escriche-Tur, Luis; Font-Bardia, Mercè; Albela, Belén; Corbella, Montserrat

    2016-07-19

    Five new dinuclear Mn(iii) compounds with benzoato derivative bridges [{Mn(bpy)L}2(μ-O)(μ-n-RC6H4COO)2]X2 (n-R = 3-MeO, 4-MeO and 4-tBu, X = NO3(-) and ClO4(-)) were synthesised and characterised. According to X-ray diffraction, the X anions tend to be coordinated to the Mn ions and may occupy the place of the monodentate ligand L. Two structural isomers that only differ in one of their monodentate ligands have been obtained with the 3-MeOC6H4COO(-) bridges. For all compounds, the Mn(iii) ions display elongated octahedra with a pronounced rhombic distortion. To quantify these distortions separately, the elongation and rhombicity parameters Δ and ρ have been defined. The magnetic study shows a good relationship between the distortion of the coordination polyhedra and the zero field splitting parameters (DMn and EMn). From the magnetic data of a powder sample, it is possible to determine the sign and magnitude of DMn for ferromagnetic systems or weak antiferromagnetic systems with DMn < 0. For this kind of dinuclear compound, the R group at the meta position, the rhombic distortion of the octahedra, and large torsion angles between the Jahn-Teller axes lead to ferromagnetic interactions.

  19. Energy-storage properties and electrocaloric effect of Pb(1-3x/2)LaxZr0.85Ti0.15O3 antiferroelectric thick films.

    PubMed

    Zhao, Ye; Hao, Xihong; Zhang, Qi

    2014-07-23

    Antiferroelectric (AFE) thick (1 μm) films of Pb(1-3x/2)LaxZr0.85Ti0.15O3 (PLZT) with x = 0.08, 0.10, 0.12, and 0.14 were deposited on LaNiO3/Si (100) substrates by a sol-gel method. The dielectric properties, energy-storage performance, electrocaloric effect, and leakage current behavior were investigated in detail. With increasing La content, dielectric constant and saturated polarizations of the thick films were gradually decreased. A maximum recoverable energy-storage density of 38 J/cm(3) and efficiency of 71% were achieved in the thick films with x = 0.12 at room temperature. A large reversible adiabatic temperature change of ΔT = 25.0 °C was presented in the thick films with x = 0.08 at 127 °C at 990 kV/cm. Moreover, all the samples had a lower leakage current density below 10(-6) A/cm(2) at room temperature. These results indicated that the PLZT AFE thick films could be a potential candidate for applications in high energy-storage density capacitors and cooling devices.

  20. Effect of La and Sr co-doping on electric and magnetic properties of multiferroic La0.1Bi0.9-xSrxFeO(3-x/2) ceramics

    NASA Astrophysics Data System (ADS)

    Guo, Feng; Wang, Shouyu; Liu, Weifang; Wang, Xu; Liu, Li; Li, Meng

    2015-09-01

    La0.1Bi0.9-xSrxFeO(3-x/2)(LBFSx0 ≤ x ≤ 0.8) ceramics were synthesized by solid-state reaction method, and their magnetic properties and conductive characteristics were investigated and discussed. It is found that La-doped BiFeO3 ceramic without Sr2+ doping is a rhombohedrally distorted perovskite structure, and with the increase of the Sr2+ concentration, the phase transits gradually from rhombohedral to pseudo cubic symmetry. Electrical and magnetic properties show strong dependence on Sr2+ dopant level. The measurement demonstrates that LBFSx with 30% Sr2+ dopant exhibits the lowest values of the leakage current, dielectric constant (ɛ) and dielectric loss (tan δ). And the highest value of saturation magnetization of about 4.5 emu/g is observed in 60% Sr-doped LBFSx. An abnormal enhancement of the conductivity was observed in LBFSx ceramics with x = 0.60 and 0.70, and their magnitude of conductivity is nearly six orders larger than that of pure LBFSx.

  1. New insights into the comprehension of the magnetic properties of dinuclear Mn(III) compounds with the general formula [{MnL(NN)}2(μ-O)(μ-n-RC6H4COO)2]X2.

    PubMed

    Escriche-Tur, Luis; Font-Bardia, Mercè; Albela, Belén; Corbella, Montserrat

    2016-07-19

    Five new dinuclear Mn(iii) compounds with benzoato derivative bridges [{Mn(bpy)L}2(μ-O)(μ-n-RC6H4COO)2]X2 (n-R = 3-MeO, 4-MeO and 4-tBu, X = NO3(-) and ClO4(-)) were synthesised and characterised. According to X-ray diffraction, the X anions tend to be coordinated to the Mn ions and may occupy the place of the monodentate ligand L. Two structural isomers that only differ in one of their monodentate ligands have been obtained with the 3-MeOC6H4COO(-) bridges. For all compounds, the Mn(iii) ions display elongated octahedra with a pronounced rhombic distortion. To quantify these distortions separately, the elongation and rhombicity parameters Δ and ρ have been defined. The magnetic study shows a good relationship between the distortion of the coordination polyhedra and the zero field splitting parameters (DMn and EMn). From the magnetic data of a powder sample, it is possible to determine the sign and magnitude of DMn for ferromagnetic systems or weak antiferromagnetic systems with DMn < 0. For this kind of dinuclear compound, the R group at the meta position, the rhombic distortion of the octahedra, and large torsion angles between the Jahn-Teller axes lead to ferromagnetic interactions. PMID:27295557

  2. Molten salt synthesis of a mixed-valent lanthanide(III/IV) oxychloride with an unprecedented Sillen X(2)(4) structure: Ce1.3Nd0.7O3Cl.

    PubMed

    Vigier, Jean-François; Renard, Catherine; Henry, Natacha; Laplace, Annabelle; Abraham, Francis

    2012-04-01

    A new cerium neodymium oxychloride, Ce1.3Nd0.7O3Cl, has been synthesized by precipitation in a LiCl–CaCl2 molten salt by humid argon sparging. Chemical and structure characterization have been undertaken by powder X-ray diffraction, scanning electron microscopy, high-temperature X-ray diffraction, thermogravimetric analysis, and X-ray photoelectron scattering. This oxychloride crystallizes in space group P4/nmm, a = 3.9848(3) Å and c = 12.467(2) Å, in a new Sillen-type phase represented by the symbol X(2)(4) where “quadruple” fluorite-type layers [M4O6], containing Ce(IV) in “inner” sublayers and both CeIII and NdIII in “outer” sublayers, alternate with double-halide ion sheets. The structure is also described as a stacking of LnOCl and fluorite-type blocks and constitutes the term n = 2 of a possible series (MO2)n(NdOCl)2.

  3. Incommensurate modulation and thermal expansion of Sr3B(2 + x)Si(1 - x)O(8 - x/2) solid solutions.

    PubMed

    Volkov, Sergey; Bubnova, Rimma; Bolotina, Nadezhda; Krzhizhanovskaya, Maria; Belousova, Olga; Filatov, Stanislav

    2015-10-01

    Crystal structures of Sr3B(2 + x)Si(1 - x)O(8 - x/2) solid solutions with nominal compositions x = 0.28, 0.53, 0.78 in the Sr3B2SiO8-Sr2B2O5 section of the SrO-B2O3-SiO2 system are refined using single-crystal X-ray diffraction data. Incommensurate structure modulations are mainly associated with various orientations of corner-sharing (B,Si)-polyhedra. Preference is given to the (3 + 2)-dimensional symmetry group Pnma(0βγ)000(0βγ)000 for a single crystal compared with an alternate model of a twin formed by monoclinic components, each of them corresponding to the (3 + 1)-dimensional symmetry group P2(1)/n(0βγ). Single-phase polycrystalline samples of solid solutions are investigated by high-temperature X-ray powder diffraction in air. Orientation preferences of the BO3 units lead to a strong anisotropy of thermal expansion. Negative expansion is observed along the a axis over the temperature range 303-753 K. Anisotropy decreases both on heating and decreasing of the boron content. PMID:26428398

  4. COSMO-RS analysis on mixing properties obtained for the systems 1-butyl-X-methylpyridinium tetrafluoroborate [X = 2,3,4] and 1,ω-dibromoalkanes [ω = 1-6].

    PubMed

    Navas, Ana; Ortega, Juan; Palomar, José; Díaz, Carlos; Vreekamp, Remko

    2011-05-01

    A theoretical-experimental study for a set of 18 binary systems comprised of [bXmpy][BF(4)] (X=2-4) + 1,ω-Br(CH(2))(v)Br (v =ω=1-6) at a temperature of 298.15 K is presented. The solubility curves are determined for each binary system, establishing the intervals of measurement for the excess properties, H(E)(m) and V(E)(m). These properties are then determined for those systems that present a miscibility zone. Binary systems containing 1,ω-dibromoalkanes with ω=5,6 present reduced solubility intervals at the temperature of 298.15 K. However, the mixtures with 1,1-dibromomethane were totally miscible with the three isomers of 1-butyl-X-methylpyridinium tetrafluoroborate. Mixtures with dibromomethane present H(E)(m) <0, whereas H(E)(m) >0 for the other binary systems. Sigmoidal curves were observed for the V(E)(m) describing expansion and contraction processes for all the systems, except for the mixtures of [b2mpy][BF(4)] with the smaller dibromoalkanes, which present contraction effects. The COSMO-RS methodology was used to estimate the solubilities and the intermolecular interaction energies, giving an acceptable explanation of the behavioral structure of pure compounds and solutions.

  5. Pseudo Jahn-Teller origin of instability of planar configurations of hexa-heterocycles. Application to compounds with 1,2- and 1,4-C4X2 skeletons (X = O, S, Se, Te)

    NASA Astrophysics Data System (ADS)

    Ilkhani, Ali R.; Hermoso, Willian; Bersuker, Isaac B.

    2015-10-01

    The driving force of symmetry breaking in planar molecular-ring systems in nondegenerate states is the pseudo Jahn-Teller effect (PJTE), and the knowledge of the mechanism of the latter allows one to manipulate the molecular properties, in particular, by restoring the planar configuration. We explore the PJTE induced structural nonplanarity in a series of 12 hexa-heterocycles with a C4X2 skeleton, 1,2- and 1,4-dichalcogenins with X = O, S, Se, Te, and a variety of ligands (H, F, Cl, Br). All the structures are optimized in both distorted equilibrium and unstable planar configurations, and the vibrational frequencies of the latter are evaluated. Then the energy profiles of the ground and several excited states in the planar configuration along the coordinate of instability are calculated, the excited states producing the instability of the ground state via the PJTE are revealed, and the vibronic coupling constants are estimated by means of fitting the solutions of the secular equations to the corresponding energy profiles.

  6. Nd2±xZr2∓xO7±x/2 (-0.2≤x≤0.4) complex oxides: Effect of anion disorder on ionic conductivity

    NASA Astrophysics Data System (ADS)

    Anithakumari, P.; Grover, V.; Tyagi, A. K.

    2016-05-01

    In the present work, a series of Nd2±xZr2∓xO7±x/2 (-0.2≤x≤0.4) was prepared by self assisted gel-combution method followed by high temperature sintering at 1673 K. Thorough structural characterizations were done by X-ray diffraction and Raman spectroscopic techniques. The nominal compositions Nd1.6Zr2.4O7.2 and Nd1.8Zr2.2O7.1 were found to possess single-phasic pyrochlore structure whereas Nd2.0Zr2.0O7 and Nd2.2Zr1.8O6.9 consisted of a pyrochlore phase and a small amount of hexagonal Nd2O3 as an impurity phase. Electrical behavior of the samples was examined by AC impedance analysis. Even though the activation energies of all the samples are not very different, a high pre-exponential factor for the Nd1.6Zr2.4O7.2 composition resulted in high ionic conductivity (3.37 × 10-3 Scm-1 at 773 K). This high ionic conductivity value makes it a superior candidate as an electrolyte material for SOFC applications.

  7. Study on the A2Π3/2u, B2Δ3/2u, and X2Π3/2g states of including its isotopologues

    NASA Astrophysics Data System (ADS)

    Wu, Ling; You, Su-Ping; Shao, Xu-Ping; Chen, Gang-Jin; Ding, Ning; Wang, You-Mei; Yang, Xiao-Hua

    2015-08-01

    Adopting the experimentally available vibrational constants in a recent analysis of the strong perturbation between the A2Π3/2u and B2Δ3/2u states of in the A-X band system [Gharaibeh et al. 2012 J. Chem. Phys. 137 194317], an unambiguous vibrational assignment of the bands reported previously is carried out. The equilibrium rotational constants Be and αe of the X2Π3/2g and A2Π3/2u states for and 35Cl37Cl+ and those of the B2Δ3/2u state for are obtained by fitting the experimental values of Bυ. In addition, the values of Be and αe of these three states for the minor isotopologues 35Cl37Cl+ and are predicted by employing the isotopic effect. The values of equilibrium internuclear distance Re of the three states for the three isotopologues are calculated as well. Project supported by the Natural Science Foundation of Zhejiang Province, China (Grant Nos. Y6110524 and Y1111085), the Scientific Research Foundation of the Department of Education of Zhejiang Province, China (Grant No. Y201430970), the National Nature Science Foundation of China (Grant No. 11247007), and the QingLan Project of Jiangsu Province, China.

  8. Crossed-beam reaction of carbon atoms with sulfur containing molecules. I. Chemical dynamics of thioformyl (HCS X2A') formation from reaction of C(3Pj) with hydrogen sulfide, H2S(X1A1)

    NASA Astrophysics Data System (ADS)

    Kaiser, R. I.; Ochsenfeld, C.; Head-Gordon, M.; Lee, Y. T.

    1999-02-01

    The reaction between ground state carbon atoms, C(3Pj), and hydrogen sulfide, H2S(X1A1), was studied at four average collision energies between 16.7 and 42.8 kJ mol-1 using the crossed molecular beam technique. The reaction dynamics were deducted from time-of-flight spectra and from laboratory angular distributions combined with ab initio calculations. These data suggest that the reaction proceeds through an addition of C(3Pj) to the sulfur atom to form a triplet CSH2 van der Waals complex. Successive H atom migration on the triplet or singlet surface forms a thiohydroxycarbene intermediate, HCSH, which decomposes through a tight exit transition state to HCS(X2A')+H(2S1/2). At lower collision energies, a weak L-L' coupling leads to isotropic center-of-mass angular distributions. As the collision energy rises, the angular distributions show increasing forward scattering thereby documenting that the reaction goes through an osculating HCSH complex. Identification of the HCS isomer under single collision conditions is a potential one-step pathway by which to form organo-sulfur molecules in interstellar environments during the collision of the comet Shoemaker-Levy 9 with Jupiter, and in combustion flames of sulfur containing fuels.

  9. Ethanol Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book chapter reviews the current process technologies for fuel ethanol production. In the US, almost all commercial fuel ethanol is produced from corn whereas cane sugar is used almost exclusively in Brazil. In Europe, two major types of feedstock considered for fuel ethanol production are be...

  10. Agricultural Production.

    ERIC Educational Resources Information Center

    Lehigh County Area Vocational-Technical School, Schnecksville, PA.

    This brochure describes the philosophy and scope of a secondary-level course in agricultural production. Addressed in the individual units of the course are the following topics: careers in agriculture and agribusiness, animal science and livestock production, agronomy, agricultural mechanics, supervised occupational experience programs, and the…

  11. Hydrogen Production

    SciTech Connect

    2014-09-01

    This 2-page fact sheet provides a brief introduction to hydrogen production technologies. Intended for a non-technical audience, it explains how different resources and processes can be used to produce hydrogen. It includes an overview of research goals as well as “quick facts” about hydrogen energy resources and production technologies.

  12. Household Products

    MedlinePlus

    ... Paint thinners, strippers and removers Pesticides Grease and rust removers Motor oil and fuel additives Arts and craft supplies Toxic substances in these products can cause harm if inhaled, swallowed, or absorbed through the ...

  13. MRCI study of spectroscopic and molecular properties of X2Πg, a 4Πu, A2Πu, b 4 ? , D2Δg and B2 ? electronic states of ? ion

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoniu; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2011-06-01

    The potential energy curves (PECs) of six low-lying electronic states (X2Πg, a 4Πu, A2Πu, b 4 ? , D2Δg and B2 ? ) of ? ion were studied by the ab initio quantum chemical method. The calculations were carried out with the full valence complete active space self-consistent field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in combination with large correlation-consistent basis sets. Effects on the PECs of the core-valence correlation and relativistic corrections are taken into account. The way to consider the relativistic correction is to use the second-order Douglas-Kroll Hamiltonian (DKH2) approximation. The core-valence correlation correction is carried out with the cc-pCVQZ basis set, and the relativistic correction is performed at the level of cc-pVQZ basis set. To obtain more reliable results, the PECs determined by the MRCI calculations are also corrected for size-extensivity errors by means of the Davidson modification (MRCI + Q). These PECs are extrapolated to the complete basis set (CBS) limit by the two-point total-energy extrapolation scheme. With these PECs, the spectroscopic parameters (Te , De , D 0, Re , ωe , ωexe , αe and Be ) are determined and compared with those reported in the literature. The conclusion can be reached that the effect on the spectroscopic parameters of the core-valence correlation correction is larger than that of the relativistic correction. With the PECs obtained by the MRCI + Q/CV+DK+56 calculations, the vibrational levels and inertial rotation constants of the first 26 vibrational states are determined for these electronic states of non-rotating ? ion. Comparison with the experimental data shows that the present spectroscopic parameters and molecular constants are accurate.

  14. Combined crossed molecular beam and ab initio investigation of the reaction of boron monoxide (BO; X(2)Σ(+)) with 1,3-butadiene (CH2CHCHCH2; X(1)Ag) and its deuterated counterparts.

    PubMed

    Maity, Surajit; Dangi, Beni B; Parker, Dorian S N; Kaiser, Ralf I; Lin, Hong-Mao; E, Hai-Ping; Sun, Bing-Jian; Chang, A H H

    2015-02-19

    The reactions of the boron monoxide ((11)BO; X(2)Σ(+)) radical with 1,3-butadiene (CH2CHCHCH2; X(1)Ag) and its partially deuterated counterparts, 1,3-butadiene-d2 (CH2CDCDCH2; X(1)Ag) and 1,3-butadiene-d4 (CD2CHCHCD2; X(1)Ag), were investigated under single collision conditions exploiting a crossed molecular beams machine. The experimental data were combined with the state-of-the-art ab initio electronic structure calculations and statistical RRKM calculations to investigate the underlying chemical reaction dynamics and reaction mechanisms computationally. Our investigations revealed that the reaction followed indirect scattering dynamics through the formation of (11)BOC4H6 doublet radical intermediates via the barrierless addition of the (11)BO radical to the terminal carbon atom (C1/C4) and/or the central carbon atom (C2/C3) of 1,3-butadiene. The resulting long-lived (11)BOC4H6 intermediate(s) underwent isomerization and/or unimolecular decomposition involving eventually at least two distinct atomic hydrogen loss pathways to 1,3-butadienyl-1-oxoboranes (CH2CHCHCH(11)BO) and 1,3-butadienyl-2-oxoboranes (CH2C ((11)BO)CHCH2) in overall exoergic reactions via tight exit transition states. Utilizing partially deuterated 1,3-butadiene-d2 and -d4, we revealed that the hydrogen loss from the methylene moiety (CH2) dominated with 70 ± 10% compared to an atomic hydrogen loss from the methylidyne group (CH) of only 30 ± 10%; these data agree nicely with the theoretically predicted branching ratio of 80% versus 19%. PMID:25626151

  15. Combined crossed molecular beam and ab initio investigation of the multichannel reaction of boron monoxide (BO; X2Σ+) with Propylene (CH3CHCH2; X1A'): competing atomic hydrogen and methyl loss pathways.

    PubMed

    Maity, Surajit; Dangi, Beni B; Parker, Dorian S N; Kaiser, Ralf I; An, Yi; Sun, Bing-Jian; Chang, A H H

    2014-10-16

    The reaction dynamics of boron monoxide ((11)BO; X(2)Σ(+)) with propylene (CH(3)CHCH(2); X(1)A') were investigated under single collision conditions at a collision energy of 22.5 ± 1.3 kJ mol(-1). The crossed molecular beam investigation combined with ab initio electronic structure and statistical (RRKM) calculations reveals that the reaction follows indirect scattering dynamics and proceeds via the barrierless addition of boron monoxide radical with its radical center located at the boron atom. This addition takes place to either the terminal carbon atom (C1) and/or the central carbon atom (C2) of propylene reactant forming (11)BOC(3)H(6) intermediate(s). The long-lived (11)BOC(3)H(6) doublet intermediate(s) underwent unimolecular decomposition involving at least three competing reaction mechanisms via an atomic hydrogen loss from the vinyl group, an atomic hydrogen loss from the methyl group, and a methyl group elimination to form cis-/trans-1-propenyl-oxo-borane (CH(3)CHCH(11)BO), 3-propenyl-oxo-borane (CH(2)CHCH(2)(11)BO), and ethenyl-oxo-borane (CH(2)CH(11)BO), respectively. Utilizing partially deuterated propylene (CD(3)CHCH(2) and CH(3)CDCD(2)), we reveal that the loss of a vinyl hydrogen atom is the dominant hydrogen elimination pathway (85 ± 10%) forming cis-/trans-1-propenyl-oxo-borane, compared to the loss of a methyl hydrogen atom (15 ± 10%) leading to 3-propenyl-oxo-borane. The branching ratios for an atomic hydrogen loss from the vinyl group, an atomic hydrogen loss from the methyl group, and a methyl group loss are experimentally derived to be 26 ± 8%:5 ± 3%:69 ± 15%, respectively; these data correlate nicely with the branching ratios calculated via RRKM theory of 19%:5%:75%, respectively. PMID:25238644

  16. Study of the formation of the apatite-type phases La9.33+x(SiO4)6O2+3x/2 synthesized from a lanthanum oxycarbonate La2O2CO3

    NASA Astrophysics Data System (ADS)

    Pons, A.; Jouin, J.; Béchade, E.; Julien, I.; Masson, O.; Geffroy, P. M.; Mayet, R.; Thomas, P.; Fukuda, K.; Kagomiya, I.

    2014-12-01

    Lanthanum silicated apatites with nominal composition La9.33+x(SiO4)6O2+3x/2 (-0.2 < x < 0.27) have been successfully synthesized by solid state reaction using a new reagent La2O2CO3 and amorphous SiO2 precursors. The formation mechanism of La2O2CO3 reagent, which cannot be purchased, has been followed by in-situ temperature depend XRD of La2O3 under CO2 atmosphere. The stability of this reagent during the synthesis step allowed to limit the formation of secondary phase La2Si2O7 and made the weighting of the reagent easier. High purity powders could be synthesized at the temperature of 1400 °C. Dense pellets (more than 98.5%) were obtained by isostatic pressing of powders calcined at 1200 °C and then sintered at 1550 °C. Traces of La2SiO5 secondary phase present in synthesized powder disappeared after densification and pure oxyapatite materials were obtained for all the compositions. Electrical measurements confirmed that conductivity behaviors of the sintered pellets were dependent to the oxygen over-stoichiometry. Indeed, a relatively high conductivity of 1 × 10-2 S cm-1 was exhibited at 800 °C for the nominal composition La9.60(SiO4)6O2.405 with low activation energy around 0.79 eV. The ionic conductivity properties were comparable with that of the earlier obtained materials.

  17. Combined crossed molecular beam and ab initio investigation of the multichannel reaction of boron monoxide (BO; X2Σ+) with Propylene (CH3CHCH2; X1A'): competing atomic hydrogen and methyl loss pathways.

    PubMed

    Maity, Surajit; Dangi, Beni B; Parker, Dorian S N; Kaiser, Ralf I; An, Yi; Sun, Bing-Jian; Chang, A H H

    2014-10-16

    The reaction dynamics of boron monoxide ((11)BO; X(2)Σ(+)) with propylene (CH(3)CHCH(2); X(1)A') were investigated under single collision conditions at a collision energy of 22.5 ± 1.3 kJ mol(-1). The crossed molecular beam investigation combined with ab initio electronic structure and statistical (RRKM) calculations reveals that the reaction follows indirect scattering dynamics and proceeds via the barrierless addition of boron monoxide radical with its radical center located at the boron atom. This addition takes place to either the terminal carbon atom (C1) and/or the central carbon atom (C2) of propylene reactant forming (11)BOC(3)H(6) intermediate(s). The long-lived (11)BOC(3)H(6) doublet intermediate(s) underwent unimolecular decomposition involving at least three competing reaction mechanisms via an atomic hydrogen loss from the vinyl group, an atomic hydrogen loss from the methyl group, and a methyl group elimination to form cis-/trans-1-propenyl-oxo-borane (CH(3)CHCH(11)BO), 3-propenyl-oxo-borane (CH(2)CHCH(2)(11)BO), and ethenyl-oxo-borane (CH(2)CH(11)BO), respectively. Utilizing partially deuterated propylene (CD(3)CHCH(2) and CH(3)CDCD(2)), we reveal that the loss of a vinyl hydrogen atom is the dominant hydrogen elimination pathway (85 ± 10%) forming cis-/trans-1-propenyl-oxo-borane, compared to the loss of a methyl hydrogen atom (15 ± 10%) leading to 3-propenyl-oxo-borane. The branching ratios for an atomic hydrogen loss from the vinyl group, an atomic hydrogen loss from the methyl group, and a methyl group loss are experimentally derived to be 26 ± 8%:5 ± 3%:69 ± 15%, respectively; these data correlate nicely with the branching ratios calculated via RRKM theory of 19%:5%:75%, respectively.

  18. Identification of mixed bromidochloridotellurate anions in disordered crystal structures of (bdmim)2[TeX2Y4] (X, Y=Br, Cl; bdmim=1-butyl-2,3-dimethylimidazolium) by combined application of Raman spectroscopy and solid-state DFT calculations.

    PubMed

    Närhi, Sari M; Kutuniva, Johanna; Lajunen, Marja K; Lahtinen, Manu K; Tuononen, Heikki M; Karttunen, Antti J; Oilunkaniemi, Raija; Laitinen, Risto S

    2014-01-01

    The discrete mixed [TeBrxCl6-x](2-) anions in their disordered crystal structures have been identified by using the phases prepared by the reaction of 1-butyl-2,3-dimethylimidazolium halogenides (bdmim)X with tellurium tetrahalogenides TeX4 (X=Cl, Br) as examples. Homoleptic (bdmim)2[TeX6] [X=Cl (1), Br (2)] and mixed (bdmim)2[TeBr2Cl4] (3), and (bdmim)2[TeBr4Cl2] (4) are formed depending on the choice of the reagents, and their crystal structures have been determined by single-crystal X-ray diffraction. The coordination environments of tellurium in all hexahalogenidotellurates are almost octahedral. Because of the crystallographic disorder, the mixed [TeBr2Cl4](2-) and [TeBr4Cl2](2-) anions in 3 and 4 cannot be identified in their crystal structures. Pawley refinement of the X-ray powder diffraction patterns of 1-4 indicates the presence of single phases in all four products. The solid state Raman spectra of 1-4 were assigned with help of DFT calculations that were performed both for the discrete anions in vacuum and for the complete crystal structures employing periodic boundary conditions. The fundamental vibrations of the homoleptic [TeX6](2-) (X=Cl, Br) anions could be well reproduced by the solid-state DFT computations and enabled a complete assignment of the Raman spectra. While the presence of cis-isomers in both [TeBr2Cl4](2-) and [TeBr4Cl2](2-) could be inferred by the computed fundamental vibrations, that of trans-isomers among the reaction products is, however, also possible. The pathway of the formation of [TeX4Y2](2-) isomers from TeX4 and Y(-) (X, Y=Cl, Br) was also explored by DFT calculations both in vacuum and in solution and indicated that both reactions afforded 80 mol% of cis-isomers and 20 mol% of trans-isomers.

  19. Production of Reactive Oxygen Species, Alteration of Cytosolic Ascorbate Peroxidase, and Impairment of Mitochondrial Metabolism Are Early Events in Heat Shock-Induced Programmed Cell Death in Tobacco Bright-Yellow 2 Cells1

    PubMed Central

    Vacca, Rosa Anna; de Pinto, Maria Concetta; Valenti, Daniela; Passarella, Salvatore; Marra, Ersilia; De Gara, Laura

    2004-01-01

    To gain some insight into the mechanisms by which plant cells die as a result of abiotic stress, we exposed tobacco (Nicotiana tabacum) Bright-Yellow 2 cells to heat shock and investigated cell survival as a function of time after heat shock induction. Heat treatment at 55°C triggered processes leading to programmed cell death (PCD) that was complete after 72 h. In the early phase, cells undergoing PCD showed an immediate burst in hydrogen peroxide (H2O2) and superoxide (O2·-) anion production. Consistently, death was prevented by the antioxidants ascorbate (ASC) and superoxide dismutase (SOD). Actinomycin D and cycloheximide, inhibitors of transcription and translation, respectively, also prevented cell death, but with a lower efficiency. Induction of PCD resulted in gradual oxidation of endogenous ASC; this was accompanied by a decrease in both the amount and the specific activity of the cytosolic ASC peroxidase (cAPX). A reduction in cAPX gene expression was also found in the late PCD phase. Moreover, changes of cAPX kinetic properties were found in PCD cells. Production of ROS in PCD cells was accompanied by early inhibition of glucose (Glc) oxidation, with a strong impairment of mitochondrial function as shown by an increase in cellular NAD(P)H fluorescence, and by failure of mitochondria isolated from cells undergoing PCD to generate membrane potential and to oxidize succinate in a manner controlled by ADP. Thus, we propose that in the early phase of tobacco Bright-Yellow 2 cell PCD, ROS production occurs, perhaps because of damage of the cell antioxidant system, with impairment of the mitochondrial oxidative phosphorylation. PMID:15020761

  20. Changes in plasma steroid levels during oocyte development in Indian shad, Tenualosa ilisha (Hamilton, 1822): role of gonadotropins on in vitro steroid production and development of oocyte maturational competence.

    PubMed

    Pramanick, Kousik; Kundu, Sourav; Paul, Sudipta; Mallick, Buddhadev; Moulik, Sujata Roy; Pal, Puja; Mukherjee, Dilip

    2013-10-01

    Circanual variations in plasma testosterone (T), 17-estradiol (E2), and 17,20-dihydroxy-4-pregnen-3-one (17,20-P) levels and ovarian steroid synthetic potential of Tenualosa ilisha of river Hooghly, West Bengal, India were examined. This fish exhibited bi-annual spawning; one during April-May and another during August-September. Coinciding with the GSI values, present study recorded a decline in plasma T and E2 levels from October, reaching their lowest values in January followed by a rapid rise in March when the ovary contained mostly vitellogenic follicles and remained high up to April (postvitellogenic stage). Plasma 17,20β-P level was detected in March and reached peak value in April during oocyte maturation. After spawning, all the steroid levels declined to reach lowest values in June. From June onwards, T and E2 levels again increased for the next cycle and peaked at the end of vitellogenesis. Plasma 17,20β-P was reappeared in August and reached maximum in September during oocyte maturation and spawning. Of the two gonadotropins tested, in vitro production of both T and E2 by the vitellogenic and postvitellogenic follicles was regulated by FSH and LH respectively. Production of 17,20-P by the post-vitellogenic follicles was regulated by LH only. Acquisition of in vitro oocyte maturational competence (OMC) was developed by the addition of HCG in culture medium. Treatment of a 3β-HSD inhibitor blocked LH-induced steroid production, but not development of OMC. Both Cycloheximide and actinomycin D inhibited LH-induced development of OMC, indicating the requirement of de novo protein synthesis for this process. PMID:24012178

  1. Sin(x)**2 + cos(x)**2 = 1. [programming identities using comparative combinatorial substitutions

    NASA Technical Reports Server (NTRS)

    Stoutemyer, D. R.

    1977-01-01

    Attempts to achieve tasteful automatic employment of the identities sin sq x + cos sq x = 1 and cos sq h x -sin sq h x = 1 in a manner which truly minimizes the complexity of the resulting expression are described. The disappointments of trigonometric reduction, trigonometric expansion, pattern matching, Poisson series, and Demoivre's theorem are related. The advantages of using the method of comparative combinatorial substitutions are illustrated.

  2. Cordless Products

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Apollo-era technology spurred the development of cordless products that we take for granted everyday. In the 1960s, NASA asked Black Decker to develop a special drill that would be powerful enough to cut through hard layers of the lunar surface and be lightweight, compact, and operate under its own power source, allowing Apollo astronauts to collect lunar samples further away from the Lunar Experiment Module. In response, Black Decker developed a computer program that analyzed and optimized drill motor operations. From their analysis, engineers were able to design a motor that was powerful yet required minimal battery power to operate. Since those first days of cordless products, Black Decker has continued to refine this technology and they now sell their rechargeable products worldwide (i.e. the Dustbuster, cordless tools for home and industrial use, and medical tools.)

  3. Bottom production

    SciTech Connect

    Baines, J.; Baranov, S.P.; Bartalini, P.; Bay, A.; Bouhova, E.; Cacciari, M.; Caner, A.; Coadou, Y.; Corti, G.; Damet, J.; Dell-Orso, R.; De Mello Neto, J.R.T.; Domenech, J.L.; Drollinger, V.; Eerola, P.; Ellis, N.; Epp, B.; Frixione, S.; Gadomski, S.; Gavrilenko, I.; Gennai, S.; George, S.; Ghete, V.M.; Guy, L.; Hasegawa, Y.; Iengo, P.; Jacholkowska, A.; Jones, R.; Kharchilava, A.; Kneringer, E.; Koppenburg, P.; Korsmo, H.; Kramer, M.; Labanca, N.; Lehto, M.; Maltoni, F.; Mangano, M.L.; Mele, S.; Nairz, A.M.; Nakada, T.; Nikitin, N.; Nisati, A.; Norrbin, E.; Palla, F.; Rizatdinova, F.; Robins, S.; Rousseau, D.; Sanchis-Lozano, M.A.; Shapiro, M.; Sherwood, P.; Smirnova, L.; Smizanska, M.; Starodumov, A.; Stepanov, N.; Vogt, R.

    2000-03-15

    In the context of the LHC experiments, the physics of bottom flavoured hadrons enters in different contexts. It can be used for QCD tests, it affects the possibilities of B decays studies, and it is an important source of background for several processes of interest. The physics of b production at hadron colliders has a rather long story, dating back to its first observation in the UA1 experiment. Subsequently, b production has been studied at the Tevatron. Besides the transverse momentum spectrum of a single b, it has also become possible, in recent time, to study correlations in the production characteristics of the b and the b. At the LHC new opportunities will be offered by the high statistics and the high energy reach. One expects to be able to study the transverse momentum spectrum at higher transverse momenta, and also to exploit the large statistics to perform more accurate studies of correlations.

  4. Using mini-rockwool blocks as growing media for limited-cluster tomato production.

    PubMed

    Logendra, L S; Gianfagna, T J; Janes, H W

    2001-01-01

    Rockwool is an excellent growing medium for the hydroponic production of tomato; however, the standard size rockwool blocks [4 x 4 x 2.5 inches (10 x 10 x 6.3 cm) or 3 x 3 x 2.5 inches (7.5 x 7.5 x 6.3 cm)] are expensive. The following experiments were conducted with less expensive minirock wool blocks (MRBs), on rayon polyester material (RPM) as a bench top liner, to reduce the production cost of tomatoes (Lycopersicon esculentum) grown in a limited-cluster, ebb and flood hydroponic cultivation system. Fruit yield for single-cluster plants growing in MRBs [2 x 2 x 1.6 inches (5 x 5 x 4 cm) and 1.6 x 1.6 x 1.6 inches (4 x 4 x 4 cm)] was not significantly different from plants grown in larger sized blocks (3 x 3 x 2.5 inches). When the bench top was lined with RPM, roots penetrated the RPM, and an extensive root mat developed between the RPM and the bench top. The fruit yield from plants on RPM was significantly increased compared to plants without RPM due to increases in fruit size and fruit number. RPM also significantly reduced the incidence of blossom-end rot. In a second experiment, single- and double-cluster plants were grown on RPM. Fruit yield for double-cluster plants was 40% greater than for single-cluster plants due to an increase in fruit number, although the fruit were smaller in size. As in the first experiment, fruit yield for all plants grown in MRBs was not significantly different from plants grown in the larger sized blocks. MRBs and a RPM bench liner are an effective combination in the production of limited-cluster hydroponic tomatoes.

  5. Using mini-rockwool blocks as growing media for limited-cluster tomato production

    NASA Technical Reports Server (NTRS)

    Logendra, L. S.; Gianfagna, T. J.; Janes, H. W.

    2001-01-01

    Rockwool is an excellent growing medium for the hydroponic production of tomato; however, the standard size rockwool blocks [4 x 4 x 2.5 inches (10 x 10 x 6.3 cm) or 3 x 3 x 2.5 inches (7.5 x 7.5 x 6.3 cm)] are expensive. The following experiments were conducted with less expensive minirock wool blocks (MRBs), on rayon polyester material (RPM) as a bench top liner, to reduce the production cost of tomatoes (Lycopersicon esculentum) grown in a limited-cluster, ebb and flood hydroponic cultivation system. Fruit yield for single-cluster plants growing in MRBs [2 x 2 x 1.6 inches (5 x 5 x 4 cm) and 1.6 x 1.6 x 1.6 inches (4 x 4 x 4 cm)] was not significantly different from plants grown in larger sized blocks (3 x 3 x 2.5 inches). When the bench top was lined with RPM, roots penetrated the RPM, and an extensive root mat developed between the RPM and the bench top. The fruit yield from plants on RPM was significantly increased compared to plants without RPM due to increases in fruit size and fruit number. RPM also significantly reduced the incidence of blossom-end rot. In a second experiment, single- and double-cluster plants were grown on RPM. Fruit yield for double-cluster plants was 40% greater than for single-cluster plants due to an increase in fruit number, although the fruit were smaller in size. As in the first experiment, fruit yield for all plants grown in MRBs was not significantly different from plants grown in the larger sized blocks. MRBs and a RPM bench liner are an effective combination in the production of limited-cluster hydroponic tomatoes.

  6. THE 2011 FEBRUARY 15 X2 FLARE, RIBBONS, CORONAL FRONT, AND MASS EJECTION: INTERPRETING THE THREE-DIMENSIONAL VIEWS FROM THE SOLAR DYNAMICS OBSERVATORY AND STEREO GUIDED BY MAGNETOHYDRODYNAMIC FLUX-ROPE MODELING

    SciTech Connect

    Schrijver, Carolus J.; Title, Alan M.; Aulanier, Guillaume; Pariat, Etienne; Delannee, Cecile E-mail: title@lmsal.com E-mail: etienne.pariat@obspm.fr

    2011-09-10

    The 2011 February 15 X2.2 flare and associated Earth-directed halo coronal mass ejection were observed in unprecedented detail with high resolution in spatial, temporal, and thermal dimensions by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory, as well as by instruments on the two STEREO spacecraft, then at near-quadrature relative to the Sun-Earth line. These observations enable us to see expanding loops from a flux-rope-like structure over the shearing polarity-inversion line between the central {delta}-spot groups of AR 11158, developing a propagating coronal front ('EIT wave'), and eventually forming the coronal mass ejection moving into the inner heliosphere. The observations support the interpretation that all of these features, including the 'EIT wave', are signatures of an expanding volume traced by loops (much larger than the flux rope only), surrounded by a moving front rather than predominantly wave-like perturbations; this interpretation is supported by previously published MHD models for active-region and global scales. The lateral expansion of the eruption is limited to the local helmet-streamer structure and halts at the edges of a large-scale domain of connectivity (in the process exciting loop oscillations at the edge of the southern polar coronal hole). The AIA observations reveal that plasma warming occurs within the expansion front as it propagates over quiet Sun areas. This warming causes dimming in the 171 A (Fe IX and Fe X) channel and brightening in the 193 and 211 A (Fe XII-XIV) channels along the entire front, while there is weak 131 A (Fe VIII and Fe XXI) emission in some directions. An analysis of the AIA response functions shows that sections of the front running over the quiet Sun are consistent with adiabatic warming; other sections may require additional heating which MHD modeling suggests could be caused by Joule dissipation. Although for the events studied here the effects of volumetric expansion are much

  7. Correlated ab initio investigations on the intermolecular and intramolecular potential energy surfaces in the ground electronic state of the O2-(X2Πg)-HF(X1Σ+) complex

    NASA Astrophysics Data System (ADS)

    Fawzy, Wafaa M.; Elsayed, Mahmoud; Zhang, Yuchen

    2013-01-01

    This work reports the first highly correlated ab initio study of the intermolecular and intramolecular potential energy surfaces in the ground electronic state of the O_2^ - (X{}^2Π _g) - HF(X{}^1Σ^+) complex. Accurate electronic structure calculations were performed using the coupled cluster method including single and double excitations with addition of the perturbative triples correction [CCSD(T)] with the Dunning's correlation consistent basis sets aug-cc-pVnZ, n = 2-5. Also, the explicitly correlated CCSD(T)-F12a level of theory was employed with the AVnZ basis as well as the Peterson and co-workers VnZ-F12 basis sets with n = 2 and 3. Results of all levels of calculations predicted two equivalent minimum energy structures of planar geometry and Cs symmetry along the A″ surface of the complex, whereas the A' surface is repulsive. Values of the geometrical parameters and the counterpoise corrected dissociation energies (Cp-De) that were calculated using the CCSD(T)-F12a/VnZ-F12 level of theory are in excellent agreement with those obtained from the CCSD(T)/aug-cc-pV5Z calculations. The minimum energy structure is characterized by a very short hydrogen bond of length of 1.328 Å, with elongation of the HF bond distance in the complex by 0.133 Å, and De value of 32.313 Kcal/mol. Mulliken atomic charges showed that 65% of the negative charge is localized on the hydrogen bonded end of the superoxide radical and the HF unit becomes considerably polarized in the complex. These results suggest that the hydrogen bond is an incipient ionic bond. Exploration of the potential energy surface confirmed the identified minimum and provided support for vibrationally induced intramolecular proton transfer within the complex. The T-shaped geometry that possesses C2v symmetry presents a saddle point on the top of the barrier to the in-plane bending of the hydrogen above and below the axis that connects centers of masses of the monomers. The height of this barrier is 7

  8. A new, definitive analysis of a very old spectrum: the highly perturbed A2Πu-X2Πg band system of the chlorine cation (Cl2+).

    PubMed

    Gharaibeh, Mohammed A; Clouthier, Dennis J; Kalemos, Apostolos; Lefebvre-Brion, Hélène; Field, Robert W

    2012-11-21

    The laser-induced fluorescence spectrum of jet-cooled chlorine cation has been recorded in the 500-312 nm region with high sensitivity and rigorous vibrational and spin-orbit cooling. More than 80 bands of the highly vibrationally perturbed A (2)Π(u)-X (2)Π(g) electronic transition have been detected and shown to originate from the Ω = 3/2 spin-orbit component of v = 0 of the ground state. The spectrum extends some 3700 cm(-1) to the red of any previously published report and the 0-0 band has been identified for the first time. The bands have regular rotational structure but exhibit irregular vibrational intervals and isotope splittings. Our ab initio studies show that the perturbations are due to a ΔΩ = 0 spin-orbit interaction between the A(2)Π(3/2u) and B(2)Δ(3/2u) states which have an avoided crossing at ~2.5 Å, which corresponds to v ≈ 4 of the A state. The nonadiabatic coupled equations have been solved for this two-state interaction after constructing the diabatic potentials including only the diagonal (ΔΛ = 0) spin-orbit coupling, yielding low-lying vibrational energy levels, isotope splittings, and rotational constants in good agreement with experiment. The calculations show that many of the observed bands are actually transitions to predominantly B state vibrational levels, which borrow oscillator strength from the A-X transition through spin-orbit mixing. Starting from the coupled equations solutions, we have fitted the experimental data using an effective Hamiltonian matrix that includes the vibrational energy levels of the A and B states and a single electronic spin-orbit coupling term H(SO)(AB) which has a value of 240 cm(-1). Transitions up to v' = 32 in both states have been satisfactorily fitted for all three chlorine isotopologues, providing a quantitative description of the perturbations. Transitions to higher levels are complicated by interactions with other electronic states.

  9. The Third Dimension of a More O'Ferrall-Jencks Diagram for Hydrogen Atom Transfer in the Isoelectronic Hydrogen Exchange Reactions of (PhX)(2)H(•) with X = O, NH, and CH(2).

    PubMed

    Cembran, Alessandro; Provorse, Makenzie R; Wang, Changwei; Wu, Wei; Gao, Jiali

    2012-11-13

    A critical element in theoretical characterization of the mechanism of proton-coupled electron transfer (PCET) reactions, including hydrogen atom transfer (HAT), is the formulation of the electron and proton localized diabatic states, based on which a More O'Ferrall-Jencks diagram can be represented to determine the step-wise and concerted nature of the reaction. Although the More O'Ferrall-Jencks diabatic states have often been used empirically to develop theoretical models for PCET reactions, the potential energy surfaces for these states have never been determined directly based on first principles calculations using electronic structure theory. The difficulty is due to a lack of practical method to constrain electron and proton localized diabatic states in wave function or density functional theory calculations. Employing a multistate density functional theory (MSDFT), in which the electron and proton localized diabatic configurations are constructed through block-localization of Kohn-Sham orbitals, we show that distinction between concerted proton-electron transfer (CPET) and HAT, which are not distinguishable experimentally from phenomenological kinetic data, can be made by examining the third dimension of a More O'Ferrall-Jencks diagram that includes both the ground and excited state potential surfaces. In addition, we formulate a pair of effective two-state valence bond models to represent the CPET and HAT mechanisms. We found that the lower energy of the CPET and HAT effective diabatic states at the intersection point can be used as an energetic criterion to distinguish the two mechanisms. In the isoelectronic series of hydrogen exchange reaction in (PhX)(2)H(•), where X = O, NH, and CH(2), there is a continuous transition from a CPET mechanism for the phenoxy radical-phenol pair to a HAT process for benzyl radical and toluene, while the reaction between PhNH(2) and PhNH(•) has a mechanism intermediate of CPET and HAT. The electronically nonadiabatic

  10. High-Resolution Pfi-Zeke Photoelectron Spectroscopy of Cl_2: the Ground (X^+ ^2π{g}) and First Excited (A^+ ^2π{u}) Electronic States of Cl_2^+

    NASA Astrophysics Data System (ADS)

    Mollet, Sandro; Merkt, Frederic

    2012-06-01

    Recently, two studies have been devoted to the low-lying electronic states of Cl_2^+, one by PFI-ZEKE photoelectron (PE) spectroscopy of the {X}^+←{X} transition and one by laser-induced-fluorescence spectroscopy of the {A}^+→{X}^+ band system. To complement the information available on the X^+ and A^+ electronic states of Cl_2^+, we have recorded partially rotationally resolved single-photon PFI-ZEKE PE spectra of the {X}^+ ^2π{g,i}←{X} ^1Σg^+ and {A}^+ ^2π{u,i}←{X} ^1Σg^+ (i=3/2, 1/2) photoionizing transitions of Cl_2 in the wavenumber ranges 92 500-96 500 {cm}-1 and 106 750-115 500 {cm}-1. These regions correspond to transitions to low-lying vibrational levels of the X^+ state with v^+=0-5 and to transitions to vibrational levels of the X^+ state with v^+=25-45 and vibrational levels of the A^+ state with v^+≤ 7. The analysis of the rotational structure and the isotopic shifts of these spectra has enabled the derivation of an improved value of the first adiabatic ionization energy (92 647.7±0.3 {cm}-1 for 35Cl_2). In combination with measurements of ion-pair states with n≈ 1800 new values for the dissociation energies D_0 of Cl_2 and Cl_2^+ could also be derived. The potential energy function of the X^+ state of Cl_2^+ was determined in a least-squares fitting procedure. Spin-orbit splittings were derived for many vibrational levels of the X^+ and A^+ states. Combining our results with other resultsb, several low-lying vibrational levels of the upper spin-orbit component of the A^+ state could be assigned for the first time. The PFI-ZEKE PE spectra also contain a series of as yet unassigned lines and reveal numerous perturbations. J. Li, Y. Hao, J. Yang, C. Zhou, and Y. Mo}, J. Chem. Phys. 127, 104307 (2007). M. A. Gharaibeh, and D. J. Clouthier, 66th Int. Symposium on Molecular Spectroscopy, Book of Abstracts, p. 169 (2011). S. Mollet, and F. Merkt, Phys. Rev. A 82, 032510 (2010). R. P. Tuckett, and S. D. Peyerimhoff, Chem. Phys. 83, 203 (1984

  11. Formation of the 2,3-Dimethyl-1-silacycloprop-2-enylidene Molecule via the Crossed Beam Reaction of the Silylidyne Radical (SiH; X(2)Π) with Dimethylacetylene (CH3CCCH3; X(1)A1g).

    PubMed

    Yang, Tao; Thomas, Aaron M; Dangi, Beni B; Kaiser, Ralf I; Wu, Mei-Hung; Sun, Bing-Jian; Chang, Agnes H H

    2016-09-22

    We carried out crossed molecular beam experiments and electronic structure calculations to unravel the chemical dynamics of the reaction of the silylidyne(-d1) radical (SiH/SiD; X(2)Π) with dimethylacetylene (CH3CCCH3; X(1)A1g). The chemical dynamics were indirect and initiated by the barrierless addition of the silylidyne radical to both carbon atoms of dimethylacetylene forming a cyclic collision complex 2,3-dimethyl-1-silacyclopropenyl. This complex underwent unimolecular decomposition by atomic hydrogen loss from the silicon atom via a loose exit transition state to form the novel 2,3-dimethyl-1-silacycloprop-2-enylidene isomer in an overall exoergic reaction (experimentally: -29 ± 21 kJ mol(-1); computationally: -10 ± 8 kJ mol(-1)). An evaluation of the scattering dynamics of silylidyne with alkynes indicates that in each system, the silylidyne radical adds barrierlessly to one or to both carbon atoms of the acetylene moiety, yielding an acyclic or a cyclic collision complex, which can also be accessed via cyclization of the acyclic structures. The cyclic intermediate portrays the central decomposing complex, which fragments via hydrogen loss almost perpendicularly to the rotational plane of the decomposing complex exclusively from the silylidyne moiety via a loose exit transition state in overall weakly exoergic reaction leading to ((di)methyl-substituted) 1-silacycloprop-2-enylidenes (-1 to -13 kJ mol(-1) computationally; -12 ± 11 to -29 ± 21 kJ mol(-1) experimentally). Most strikingly, the reaction dynamics of the silylidyne radical with alkynes are very different from those of C1-C4 alkanes and C2-C4 alkenes, which do not react with the silylidyne radical at the collision energies under our crossed molecular beam apparatus, due to either excessive entrance barriers to reaction (alkanes) or overall highly endoergic reaction processes (alkenes). Nevertheless, molecules carrying carbon-carbon double bonds could react, if the carbon-carbon double bond is

  12. A new, definitive analysis of a very old spectrum: The highly perturbed A2Πu-X 2Πg band system of the chlorine cation (Cl_2^ +)

    NASA Astrophysics Data System (ADS)

    Gharaibeh, Mohammed A.; Clouthier, Dennis J.; Kalemos, Apostolos; Lefebvre-Brion, Hélène; Field, Robert W.

    2012-11-01

    The laser-induced fluorescence spectrum of jet-cooled chlorine cation has been recorded in the 500-312 nm region with high sensitivity and rigorous vibrational and spin-orbit cooling. More than 80 bands of the highly vibrationally perturbed A 2Πu-X 2Πg electronic transition have been detected and shown to originate from the Ω = 3/2 spin-orbit component of v = 0 of the ground state. The spectrum extends some 3700 cm-1 to the red of any previously published report and the 0-0 band has been identified for the first time. The bands have regular rotational structure but exhibit irregular vibrational intervals and isotope splittings. Our ab initio studies show that the perturbations are due to a ΔΩ = 0 spin-orbit interaction between the A2Π3/2u and B2Δ 3/2u states which have an avoided crossing at ˜2.5 Å, which corresponds to v ≈ 4 of the A state. The nonadiabatic coupled equations have been solved for this two-state interaction after constructing the diabatic potentials including only the diagonal (ΔΛ = 0) spin-orbit coupling, yielding low-lying vibrational energy levels, isotope splittings, and rotational constants in good agreement with experiment. The calculations show that many of the observed bands are actually transitions to predominantly B state vibrational levels, which borrow oscillator strength from the A-X transition through spin-orbit mixing. Starting from the coupled equations solutions, we have fitted the experimental data using an effective Hamiltonian matrix that includes the vibrational energy levels of the A and B states and a single electronic spin-orbit coupling term H_{SO}^{AB} which has a value of 240 cm-1. Transitions up to v' = 32 in both states have been satisfactorily fitted for all three chlorine isotopologues, providing a quantitative description of the perturbations. Transitions to higher levels are complicated by interactions with other electronic states.

  13. Formation of the 2,3-Dimethyl-1-silacycloprop-2-enylidene Molecule via the Crossed Beam Reaction of the Silylidyne Radical (SiH; X(2)Π) with Dimethylacetylene (CH3CCCH3; X(1)A1g).

    PubMed

    Yang, Tao; Thomas, Aaron M; Dangi, Beni B; Kaiser, Ralf I; Wu, Mei-Hung; Sun, Bing-Jian; Chang, Agnes H H

    2016-09-22

    We carried out crossed molecular beam experiments and electronic structure calculations to unravel the chemical dynamics of the reaction of the silylidyne(-d1) radical (SiH/SiD; X(2)Π) with dimethylacetylene (CH3CCCH3; X(1)A1g). The chemical dynamics were indirect and initiated by the barrierless addition of the silylidyne radical to both carbon atoms of dimethylacetylene forming a cyclic collision complex 2,3-dimethyl-1-silacyclopropenyl. This complex underwent unimolecular decomposition by atomic hydrogen loss from the silicon atom via a loose exit transition state to form the novel 2,3-dimethyl-1-silacycloprop-2-enylidene isomer in an overall exoergic reaction (experimentally: -29 ± 21 kJ mol(-1); computationally: -10 ± 8 kJ mol(-1)). An evaluation of the scattering dynamics of silylidyne with alkynes indicates that in each system, the silylidyne radical adds barrierlessly to one or to both carbon atoms of the acetylene moiety, yielding an acyclic or a cyclic collision complex, which can also be accessed via cyclization of the acyclic structures. The cyclic intermediate portrays the central decomposing complex, which fragments via hydrogen loss almost perpendicularly to the rotational plane of the decomposing complex exclusively from the silylidyne moiety via a loose exit transition state in overall weakly exoergic reaction leading to ((di)methyl-substituted) 1-silacycloprop-2-enylidenes (-1 to -13 kJ mol(-1) computationally; -12 ± 11 to -29 ± 21 kJ mol(-1) experimentally). Most strikingly, the reaction dynamics of the silylidyne radical with alkynes are very different from those of C1-C4 alkanes and C2-C4 alkenes, which do not react with the silylidyne radical at the collision energies under our crossed molecular beam apparatus, due to either excessive entrance barriers to reaction (alkanes) or overall highly endoergic reaction processes (alkenes). Nevertheless, molecules carrying carbon-carbon double bonds could react, if the carbon-carbon double bond is

  14. Television Production.

    ERIC Educational Resources Information Center

    El Monte Union High School District, Rosemead, CA.

    An overview of the Rosemead High School (California) student-operated educational television system (KRHS) is presented, starting with its inception in 1964. Briefly described are the development of KRHS into a closed-circuit production facility with editing capabilities; awards that KRHS programs have won; places that KRHS student crews have…

  15. Television Production.

    ERIC Educational Resources Information Center

    Hird, John R.; Balzarini, Steven

    This document is a course of study to provide high school students with an introduction to television production skills and techniques and to provide a framework for developing critical television viewing skills. The nine units of the course introduce students to storyboards, camera operations, lighting, audio, video recording, graphics,…

  16. Transplant production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For field pepper (Capsicum spp.) production, plants can be established from direct seed or transplants depending on the location and cultural practices for the specific pepper type grown. Direct seeding can result in slow, variable, and reduced plant stands due to variations in soil temperature, wat...

  17. Secondary Products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In spite of their name, "secondary" products are essential for plant survival. They are required for basic cell functions as well as communicating the plant's presence to the surrounding environment and defense against pests as defined in the broad sense (i.e., diseases, nematodes, insects and plan...

  18. Novolak Production

    NASA Astrophysics Data System (ADS)

    Aiba, Hiroshi

    Novolak resins are produced by reacting formaldehyde (30-55% concentration) with phenol under acidic conditions, with oxalic acid as the preferred catalyst and in special conditions, sulfuric acid. Depending on the batch size, all raw material components can be introduced into the reactor, or when there is an increase in the batch size as well as in the reactor volume, the reaction exotherm is controlled by a gradual addition of formaldehyde. Modern novolak production facilities are automated and programmed for reduced operational cost. A flow diagram of a general production line for the manufacture of novolak is shown. Recovery of the novolak is accomplished by the removal of water and devolatilization of crude novolak to molten, low-free phenol novolak resin which can be isolated as flake or pastille or dissolved in appropriate solvents. Novolak is stored either in a solid flake or pastille form or in solution. Most production is conducted under atmospheric conditions, but there are some recent, novel activities such as pressure in a hermetically-closed reactor reaching 0.1-10 MPa by using the heat of reaction without reflux to shorten reaction time, accelerating dehydration time by flash distillation, and providing economic benefit in the cost of novolak production.

  19. New Products.

    ERIC Educational Resources Information Center

    TechTrends, 1992

    1992-01-01

    Reviews new educational technology products, including a microcomputer-based tutoring system, laser barcode reader, video/data projectors, CD-ROM for notebook computers, a system to increase a printer's power, data cartridge storage shell, knowledge-based decision tool, video illustrator, interactive videodiscs, surge protectors, scanner system,…

  20. Tequila production.

    PubMed

    Cedeño, M

    1995-01-01

    Tequila is obtained from the distillation of fermented juice of agave plant, Agave tequilana, to which up to 49% (w/v) of an adjunct sugar, mainly from cane or corn, could be added. Agave plants require from 8 to 12 years to mature and during all this time cleaning, pest control, and slacken of land are required to produce an initial raw material with the appropriate chemical composition for tequila production. Production process comprises four steps: cooking to hydrolyze inulin into fructose, milling to extract the sugars, fermentation with a strain of Saccharomyces cerevisiae to convert the sugars into ethanol and organoleptic compounds, and, finally, a two-step distillation process. Maturation, if needed, is carried out in white oak barrels to obtain rested or aged tequila in 2 or 12 months, respectively.

  1. Oil Production

    1989-07-01

    A horizontal and slanted well model was developed and incorporated into BOAST, a black oil simulator, to predict the potential production rates for such wells. The HORIZONTAL/SLANTED WELL MODEL can be used to calculate the productivity index, based on the length and location of the wellbore within the block, for each reservoir grid block penetrated by the horizontal/slanted wellbore. The well model can be run under either pressure or rate constraints in which wellbore pressuresmore » can be calculated as an option of infinite-conductivity. The model can simulate the performance of multiple horizontal/slanted wells in any geometric combination within reservoirs.« less

  2. Ether production

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1991-05-14

    This patent describes a multistage process for etherifying a mixed C{sub 4} + olefinic hydrocarbon feedstock containing isoalkene. It comprises: contacting the olefinic feedstock and aliphatic alcohol in a first reaction stage under partial etherification conditions with a regenerable inorganic metal oxide acid solid catalyst to convert a major amount of the isoalkene to C{sub 5} + tertiary-alkyl ether; recovering a reactant effluent from the first stage containing ether product, unreacted alcohol and unreacted olefin including isoalkene; charging the first stage effluent to a second stage catalytic distillation column containing solid acid resin etherification catalyst in a plurality of fixed bed catalysis-distillation zones to complete substantially full etherification of isoalkene; recovering C{sub 5} + ether as a liquid from the catalytic distillation column; regenerating the first stage catalyst to remove feedstock impurity and coke and to acid activity; and continuing ether production with regenerated catalyst.

  3. Petroleum products

    SciTech Connect

    Not Available

    1987-01-01

    This book is the first of three volumes devoted to petroleum products and lubricants. This volume begins with standard D 56 and contains all petroleum standards up to D 1947. It contains specifications and test methods for fuels, solvents, burner fuel oils, lubricating oils, cutting oils, lubricating greases, fluids measurement and sampling, liquified petroleum gases, light hydrocarbons, plant spray oils, sulfonates, crude petroleum, petrolatam, and wax.

  4. Product separator

    DOEpatents

    Welsh, Robert A.; Deurbrouck, Albert W.

    1976-01-20

    A secondary light sensitive photoelectric product separator for use with a primary product separator that concentrates a material so that it is visually distinguishable from adjacent materials. The concentrate separation is accomplished first by feeding the material onto a vibratory inclined surface with a liquid flow, such as a wet concentrating table. Vibrations generally perpendicular to the stream direction of flow cause the concentrate to separate from its mixture according to its color. When the concentrate and its surrounding stream reach the recovery end of the table, a detecting device notes the line of color demarcation and triggers a signal if it differs from a normal condition. If no difference is noted nothing moves on the second separator. However, if a difference is detected in the constant monitoring of the color line's location, a product splitter and recovery unit normally positioned near the color line at the recovery end, moves to a new position. In this manner the selected separated concentrate is recovered at a maximum rate regardless of variations in the flow stream or other conditions present.

  5. The A{sub 1-x}UNbO{sub 6-x/2} compounds (x=0, A=Li, Na, K, Cs and x=0.5, A=Rb, Cs): from layered to tunneled structure

    SciTech Connect

    Surble, S.; Obbade, S. . E-mail: said.obbade@ensc-lille.fr; Saad, S.; Yagoubi, S.; Dion, C.; Abraham, F.

    2006-10-15

    Attempts to prepare alkaline metal uranyl niobates of composition A{sub 1-x}UNbO{sub 6-x/2} by high-temperature solid-state reactions of A{sub 2}CO{sub 3}, U{sub 3}O{sub 8} and Nb{sub 2}O{sub 5} led to pure compounds for x=0 and A=Li (1), Na (2), K (3), Cs (4) and for x=0.5 and A=Rb (5), Cs (6). Single crystals were grown for 1, 3, 4, 5, 6 and for the mixed Na{sub 0.92}Cs{sub 0.08}UNbO{sub 6} (7) compound. Crystallographic data: 1, monoclinic, P2{sub 1}/c, a=10.3091(11), b=6.4414(10), c=7.5602(5)A, {beta}=100.65(1), Z=4, R{sub 1}=0.054 (wR{sub 2}=0.107); 3, 5 and 7 orthorhombic, Pnma, Z=8, with a=10.307(2), 10.272(4) and 10.432(3)A, b=7.588(1), 7.628(3) and 7.681(2)A, c=13.403(2), 13.451(5) and 13.853(4)A, R{sub 1}=0.023, 0.046 and 0.036 (wR{sub 2}=0.058, 0.0106 and 0.088) for 3, 5 and 7, respectively; 6, orthorhombic, Cmcm, Z=8, and a=13.952(3), b=10.607(2)A, c=7.748(2)A, R{sub 1}=0.044 (wR{sub 2}=0.117). The crystal structure of 1 is characterized by {sub {approx}}{sup 2}[UNbO{sub 6}]{sup -} layers of uranophane sheet anion topology parallel to the (100) plane. These layers are formed by the association by edge-sharing of {sub {approx}}{sup 1}[UO{sub 5}]{sup 4-} chains of edge-shared UO{sub 7} pentagonal bipyramids and {sub {approx}}{sup 1}[NbO{sub 4}]{sup 3-} chains of corner-shared NbO{sub 5} square pyramids alternating along the [010] direction. The Li{sup +} ions are located between two consecutive layers and hold them together; the Li{sup +} ions and two layers constitute a neutral ''sandwich'' {l_brace}(UNbO{sub 6}){sup -}-(Li){sub 2}{sup 2+}-(UNbO{sub 6}){sup -}{r_brace}. In this unusual structure, the neutral sandwiches are stacked one above another with no formal chemical bonds between the neutral sandwiches. The homeotypic compounds 3, 5, 6, 7 have open-framework structures built from the association by edge-sharing in two directions of parallel {sub {approx}}{sup 1}[UO{sub 5}]{sup 4-} chains of edge-shared UO{sub 7} pentagonal bipyramids and {sub

  6. The X+ 2Πg, A+ 2Πu, B+ 2Δu, and a^+ ^4Σ u^- electronic states of Cl_2^+ studied by high-resolution photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Mollet, Sandro; Merkt, Frédéric

    2013-07-01

    Partially rotationally resolved pulsed-field-ionization zero-kinetic-energy photoelectron spectra of the three isotopomers (35Cl2, 35Cl37Cl, and 37Cl2) of Cl2 have been recorded in the wavenumber ranges 92 500-96 500 cm-1, corresponding to transitions to the low vibrational levels of the X+ 2Πg (Ω = 3/2, 1/2) ground state of Cl_2^+, and 106 750-115 500 cm-1, where the a^+ ^4Σ _u^-leftarrow X ^1Σ _g^+, A^+ ^2Π _uleftarrow X ^1Σ _g^+, and B^+ ^2Δ _uleftarrow X ^1Σ _g^+ band systems overlap with transitions to high vibrational levels (v+ > 25) of the X+ state. The observation of Franck-Condon-forbidden transitions to vibrational levels of the X+ state of the cation with v+ ⩾ 25 is rationalized by a mechanism involving vertical excitation of predissociative Rydberg states of mixed singlet-triplet character with an A+ ion core which are coupled to Rydberg states converging to high-v+ levels of the X+ state. The same mechanism is proposed to also be responsible for the observation of Cl+ - Cl- ion pairs and quartet states in the photoionization of Cl2. The potential energy function of the X+ state of Cl_2^+ was determined in a direct fit to the experimental data. Transitions to vibrational levels of the A+ 2Πu, 3/2 and B+ 2Δu, 3/2 states of Cl_2^+ could be identified using the results of a recent analysis of the strong perturbation between the A+ 2Πu, 3/2 and B+ 2Δu, 3/2 states of Cl_2^+ observed in the A+ - X+ band system [Gharaibeh et al., J. Chem. Phys. 137, 194317 (2012)], 10.1063/1.4765334, and transitions to several vibrational levels of the upper spin-orbit component (2Πu, 1/2) of the A+ state were detected in the photoelectron spectrum of Cl_2^+. The a^+ ^4Σ _u^-leftarrow X ^1Σ _g^+ photoelectron band system, which is nominally forbidden by single-photon ionization from the ground state was also observed for the first time and its vibrational and spin-orbit structures were analyzed. The ^4Σ _u^- state is split into two spin-orbit components with

  7. Metallized Products

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Since the early 1960's, virtually all NASA spacecraft have used metallized films for a variety of purposes, principally thermal radiation insulation. King Seeley manufactures a broad line of industrial and consumer oriented metallized film, fabric, paper and foam in single layer sheets and multi-layer laminates. A few examples, commercialized by MPI Outdoor Safety Products, are the three ounce Thermos Emergency Blanket which reflects and retains up to 80 percent of the user's body heat helping prevent post accident shock or keeping a person warm for hours under emergency cold weather conditions.

  8. NULLJOB product

    SciTech Connect

    Hughart, N.; Ritchie, D.

    1987-05-01

    The ever increasing demand for more CPU cycles for data analysis on our Central VAX Cluster led us to investigate new ways to utilize more fully the resources that were available. A review of the experiment and software development VAX systems on site revealed many unused computing cycles. Furthermore, these systems were all connected by DECnet which would allow easy file transfer and remote batch job submission. A product was developed to allow jobs to be submitted on the Central VAX Cluster but actually to be run on one of the remote systems. The processing of the jobs was arranged, to the greatest extent possible, to be transparent to the user and to have minimal impact on both the Central VAX Cluster and remote systems.

  9. Software Products

    NASA Technical Reports Server (NTRS)

    1993-01-01

    MAST is a decision support system to help in the management of dairy herds. Data is collected on dairy herds around the country and processed at regional centers. One center is Cornell University, where Dr. Lawrence Jones and his team developed MAST. The system draws conclusions from the data and summarizes it graphically. CLIPS, which is embedded in MAST, gives the system the ability to make decisions without user interaction. With this technique, dairy managers can identify herd problems quickly, resulting in improved animal health and higher milk quality. CLIPS (C Language Integrated Production System) was developed by NASA's Johnson Space Center. It is a shell for developing expert systems designed to permit research, development and delivery on conventional computers.

  10. Reactions of the bis(dialkylphosphino)methane complexes Pd2X2(μ-R2PCH2PR2)2 (X = halogen, R = Me or Et) with H2S, S8, COS, and CS2; detection of reaction intermediates.

    PubMed

    Pamplin, Craig B; Rettig, Steven J; Patrick, Brian O; James, Brian R

    2011-09-01

    The Pd(2)X(2)(dmpm)(2) complexes [X = Cl (1a), Br (1b), I (1c); dmpm = bis(dimethylphosphino)methane. In all the dipalladium complexes mentioned in this paper, the dmpm, depm, and dppm ligands (unless stated otherwise) are bridging, but for convenience the μ-symbol is omitted.] react with H(2)S to yield H(2) and the bridged-sulfido complexes Pd(2)X(2)(μ-S)(dmpm)(2) (2a-c), of which 2a and 2b are structurally characterized. With 1a, two rapid reversible equilibria are observed by NMR spectroscopy below -30 °C, and two reaction intermediates are detected; both are likely hydrido(mercapto) species. Reaction of 1a with 1 equiv of elemental sulfur also yields 2a. The reaction of 1a with COS results in the initial formation of Pd(2)Cl(2)(μ-COS)(dmpm)(2) (3) that undergoes decarbonylation to yield 2a and Pd(2)Cl(2)(μ-CO)(dmpm)(2) (4), which is also formed via reversible insertion of the CO into the Pd-Pd bond of 1a. The solid-state molecular structure of the previously reported complex Pd(2)Cl(2)(μ-CS(2))(dmpm)(2) (5), together with solution NMR data for 3 and 5, reveal that the bridging heterocumulene ligands coordinate in an η(2)-C,S fashion. Analogous findings were made for the corresponding Pd(2)X(2)(depm)(2) complexes [X = Cl (1a'), Br (1b'), I (1c'); depm = bis(diethylphosphino)methane], although no μ-COS species was detected. The Pd(2)X(2)(μ-S)(depm)(2) complex was structurally characterized. Differences in the chemistry of the previously studied, corresponding dppm systems (dppm = bis(diphenylphosphino)methane) are discussed.

  11. Electro-optical 1 x 2, 1 x N and N x N fiber-optic and free-space switching over 1.55 to 3.0 μm using a Ge-Ge(2)Sb(2)Te(5)-Ge prism structure.

    PubMed

    Hendrickson, Joshua; Soref, Richard; Sweet, Julian; Majumdar, Arka

    2015-01-12

    New device designs are proposed and theoretical simulations are performed on electro-optical routing switches in which light beams enter and exit the device either from free space or from lensed fibers. The active medium is a ~100 nm layer of phase change material (Ge(2)Sb(2)Te(5) or GeTe) that is electrically "triggered" to change its phase, giving "self-holding" behavior in each of two phases. Electrical current is supplied to that film by a pair of transparent highly doped conducting Ge prisms on both sides of the layer. For S-polarized light incident at ~80° on the film, a three-layer Fabry-Perot analysis, including dielectric loss, predicts good 1 x 2 and 2 x 2 switch performance at infrared wavelengths of 1.55, 2.1 and 3.0 μm, although the performance at 1.55 μm is degraded by material loss and prism mismatch. Proposals for in-plane and volumetric 1 x 4 and 4 x 4 switches are also presented. An unpolarized 1 x 2 switch projects good performance at mid infrared.

  12. Electro-optical 1 x 2, 1 x N and N x N fiber-optic and free-space switching over 1.55 to 3.0 μm using a Ge-Ge(2)Sb(2)Te(5)-Ge prism structure.

    PubMed

    Hendrickson, Joshua; Soref, Richard; Sweet, Julian; Majumdar, Arka

    2015-01-12

    New device designs are proposed and theoretical simulations are performed on electro-optical routing switches in which light beams enter and exit the device either from free space or from lensed fibers. The active medium is a ~100 nm layer of phase change material (Ge(2)Sb(2)Te(5) or GeTe) that is electrically "triggered" to change its phase, giving "self-holding" behavior in each of two phases. Electrical current is supplied to that film by a pair of transparent highly doped conducting Ge prisms on both sides of the layer. For S-polarized light incident at ~80° on the film, a three-layer Fabry-Perot analysis, including dielectric loss, predicts good 1 x 2 and 2 x 2 switch performance at infrared wavelengths of 1.55, 2.1 and 3.0 μm, although the performance at 1.55 μm is degraded by material loss and prism mismatch. Proposals for in-plane and volumetric 1 x 4 and 4 x 4 switches are also presented. An unpolarized 1 x 2 switch projects good performance at mid infrared. PMID:25835655

  13. Production Density Diffusion Equation Propagation and Production

    NASA Astrophysics Data System (ADS)

    Shirai, Kenji; Amano, Yoshinori

    When we call the production flow to transition elements in the next step in the process of product manufactured one, the production flow is considered to be displaced in the direction of the unit production density. Density and production, as captured from different perspectives, also said production costs per unit of production. However, it is assumed that contributed to the production cost of manufacturing 100 percent. They may not correspond to the physical propagation conditions after each step of the production density, the equations governing the manufacturing process, which is intended to be represented by a single diffusion equation. We can also apply the concept of energy levels in statistical mechanics, production density function, in other words, in statistical mechanics “place” that if you use the world of manufacturing and production term. If the free energy in this production (potential) that are consuming the substance is nothing but the entropy production. That is, productivity is defined as the entropy production has to be. Normally, when we increase the number of production units, the product nears completion at year-end number of units completed and will aim to be delivered to the contractor from the turnover order. However, if you stop at any number of units, that will increase production density over time. Thus, the diffusion does not proceed from that would be irreversible. In other words, the congestion will occur in production. This fact and to report the results of analysis based on real data.

  14. The Conterminous United States Mineral Assessment Program; background information to accompany folio of geologic, geochemical, geophysical, and mineral resource maps of the Ajo and Lukeville 1 degree x 2 degrees quadrangles, Arizona

    USGS Publications Warehouse

    Gray, Floyd; Tosdal, R.M.; Peterson, J.A.; Cox, D.P.; Miller, R.J.; Klein, D.P.; Theobald, P.K.; Haxel, G.B.; Grubensky, M.J.; Raines, G.L.; Barton, H.N.; Singer, D.A.; Eppinger, R.G.

    1992-01-01

    Encompassing about 21,000 km 2 in southwestern Arizona, the Ajo and Lukeville 1 ? by 2 ? quadrangles have been the subject of mineral resource investigations utilizing field and laboratory studies in the disciplines of geology, geochemistry, geophysics, and Landsat imagery. The results of these studies are published as a folio of maps, figures, and tables, with accompanying discussions. Past mineral production has been limited to copper from the Ajo Mining District. In addition to copper, the quadrangles contain potentially significant resources of gold and silver; a few other commodities, including molybdenum and evaporites, may also exist in the area as appreciable resources. This circular provides background information on the mineral deposits and on the investigations and integrates the information presented in the folio. The bibliography cites references to the geology, geochemistry, geophysics, and mineral deposits of the two quadrangles.

  15. Role of glucocorticoids in increased muscle glutamine production in starvation

    NASA Technical Reports Server (NTRS)

    Tischler, Marc E.; Henriksen, Erik J.; Cook, Paul H.

    1988-01-01

    The role of glucocorticoids in the synthesis of muscle glutamine during starvation was investigated in adrenalectomized fasted rats injected with cortisol (1 mg/100 g body weight). It was found that administration of cortisol in vivo increased (compared to nontreated starved adrenalectomized controls) the glutamine/glutamate ratio and the activity of glutamine synthetase in the diaphragm and the extensor digitorum muscles, and that these effects were abolished by prior treatment with actinomycin D or proflavine. The results obtained in in vitro experiments, using fresh-frozen soleus, extensor digitorum longus, and diaphragm muscle preparations, supported the in vivo indications of the cortisol-enhanced glutamine synthesis and protein turnover in starved adrenalectomized animals.

  16. Investigation of substitution effects and the phase transition in type-I clathrates Rb{sub x}Cs{sub 8-x}Sn{sub 44}square{sub 2} (1.3<=x<=2.1) using single-crystal X-ray diffraction, Raman spectroscopy, heat capacity and electrical resistivity measurements

    SciTech Connect

    Kaltzoglou, Andreas; Faessler, Thomas F.; Gold, Christian; Scheidt, Ernst-Wilhelm; Scherer, Wolfgang; Kume, Tetsuji; Shimizu, Hiroyasu

    2009-10-15

    The substitution of cations in Rb{sub x}Cs{sub 8-x}Sn{sub 44}square{sub 2}(1.3<=x<=2.1) is reported. The compounds crystallize at room temperature in the space group la3-bard adopting the type-I clathrate 2x2x2 superstructure with partly ordered framework vacancies (square), whereas at higher temperatures they transform to the primitive, more disordered modification (space group Pm3-barn). The guest atom distributions in the Sn cages on the Rb: Cs ratios is studied by means of single-crystal X-ray diffraction for Rb{sub 2.1(1)}Cs{sub 5.8(1)}Sn{sub 44} at T=293 K (1), Rb{sub 1.42(8)}Cs{sub 6.58(8)}Sn{sub 44} at T=293 K (2a), Rb{sub 1.46(5)}Cs{sub 6.54(5)}Sn{sub 44} at T=373 K (2b) and Rb{sub 1.32(8)}Cs{sub 6.68(8)}Sn{sub 44} at T=293 K (3). The structural order-disorder phase transition influences the electrical resistivity. The hysteresis observed for the electrical resistivity in combination with the symmetric shape of the specific heat anomaly suggests that the transformation is of first-order type and is characterized by an entropy change of about 2.5 J mol{sup -1} K{sup -1}. The Raman spectrum for the low-temperature modification of 2 is also reported. - Graphical Abstract: The effects of substitution of cations in the type-I clathrates Rb{sub x}Cs{sub 8-x}Sn{sub 44} (1.3<=x<=2.1) are reported. The distribution of the guests in the Sn cages under different reaction stoichiometries and annealing times is studied by X-ray diffraction. A structural phase transition in Rb{sub 1.4}Cs{sub 6.6}Sn{sub 44} at 333-363 K affects significantly the electrical resistivity and heat capacity.

  17. Insight into inhibition of the human amyloid beta protein precursor (APP: PDB ID ) using (E)-N-(pyridin-2-ylmethylene)arylamine (LR) models: structure elucidation of a family of ZnX2-LR complexes.

    PubMed

    Basu Baul, Tushar S; Kundu, Sajal; Singh, Palwinder; Shaveta; Guedes da Silva, M Fátima C

    2015-02-01

    The amyloid beta precursor protein (APP) and its neurotoxic cleavage product amyloid beta (Aβ) are a cause of Alzheimer's disease and appear essential for neuronal development and cell homeostasis. Proteolytic processing of APP is influenced by metal ions and protein ligands, however the structural and functional mechanism of APP regulation is not known so far. In this context, molecular modeling studies were performed to understand the molecular behavior of (E)-N-(pyridin-2-ylmethylene)arylamines (LR) with an E2 domain of the APP in its complex with zinc (APP; PDB ID: ). Docking results indeed confirmed that the LR interacts with Zn in the binding site of the protein between two α-helical chains. In view of these findings, LR was further investigated for complexation reactions with Zn(2+) in order to establish the structural models in solution and in the solid state. Five new Zn(2+) complexes of compositions viz. [Zn(Br)2(L2-Me)] (), [Zn(Br)2(L2-OMe)] (), [Zn(i)2(L2-OMe)] (), [Zn(NO3)2(L2-OMe)(H2O)] () and [Zn(L4-Me)2(H2O)2](NO3)2 () were synthesized and their structures were ascertained by microanalysis, IR and (1)H NMR spectroscopy, and single-crystal X-ray diffraction. The zinc atom in complex exhibits a distorted tetrahedral geometry while the crystal structures of complexes and show distorted square pyramidal geometries. The zinc cation in and has an octahedral coordination environment, but in the zinc coordination geometry is less distorted. The Zn(ii) cations take part in one ( and ) or two () 5-membered metallacycles imposed by the NN or NNO chelation modes of LR. The significant intermolecular ππ interactions are also discussed.

  18. Biological production of products from waste gases

    DOEpatents

    Gaddy, James L.

    2002-01-22

    A method and apparatus are designed for converting waste gases from industrial processes such as oil refining, and carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various products, such as organic acids, alcohols, hydrogen, single cell protein, and salts of organic acids by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified.

  19. Isomerization of the hydride complexes [HFe2(SR)2(PR3)x(CO)6–x]+ (x = 2, 3, 4) relevant to the active site models for the [FeFe]-hydrogenases†

    PubMed Central

    Barton, Bryan E.; Zampella, Giuseppe; Justice, Aaron K.; Wilson, Scott R.

    2012-01-01

    The stepwise formation of bridging (μ-) hydrides of diiron dithiolates is discussed with attention on the pathway for protonation and subsequent isomerizations. Our evidence is consistent with protonations occurring at a single Fe center, followed by isomerization to a series of μ-hydrides. Protonation of Fe2(edt)(CO)4(dppv) (1) gave a single μ-hydride with dppv spanning apical and basal sites, which isomerized at higher temperatures to place the dppv into a dibasal position. Protonation of Fe2(pdt)(CO)4(dppv) (2) followed an isomerization pathway similar to that for [1H]+, except that a pair of isomeric terminal hydrides were observed initially, resulting from protonation at the Fe(CO)3 or Fe(CO)(dppv) site. The first observable product from low temperature protonation of the tris-phosphine Fe2(edt)(CO)3(PMe3)(dppv) (3) was a single μ-hydride wherein PMe3 is apical and the dppv ligand spans apical and basal sites. Upon warming, this isomer converted fully but in a stepwise manner to a mixture of three other isomeric hydrides. Protonation of Fe2(pdt)(CO)3(PMe3)(dppv) (4) proceeded similarly to the edt analogue 3, however a terminal hydride was observed, albeit only briefly and at very low temperatures (−90 °C). Low-temperature protonation of the bis-chelates Fe2(xdt)(CO)2(dppv)2 produced exclusively the terminal hydrides [HFe2(xdt)(μ-CO)(CO)(dppv)2]+ (xdt = edt and pdt), which subsequently isomerized to a pair of μ-hydrides. At room temperature these (dppv)2 derivatives convert to an equilibrium of two isomers, one C2-symmetric and the other Cs-symmetric. The stability of the terminal hydrides correlates with the (C2-isomer)/(Cs-isomer) equilibrium ratio, which reflects the size of the dithiolate. The isomerization was found to be unaffected by the presence of excess acid, by solvent polarity, and the presence of D2O. This isomerization mechanism is proposed to be intramolecular, involving a 120° rotation of the HFeL3 subunit to an unobserved terminal

  20. CD-ROM Catalog Production Products.

    ERIC Educational Resources Information Center

    Bills, Linda; Helgerson, Linda

    1989-01-01

    Compares database characteristics, access, display, editing, new records, hard copy products, hardware, and price of CD-ROM catalog production products from seven vendors: Gaylord Information Systems; General Research Corporation; The Library Corporation; OCLC; Solinet; Utlas; and the Western Library Network. (MES)