Facile synthesis of PdAgTe nanowires with superior electrocatalytic activity

NASA Astrophysics Data System (ADS)

Hong, Wei; Wang, Jin; Wang, Erkang

2014-12-01

In this work, ultrathin Te nanowires (NWs) with high-aspect-ratio are prepared by a simple hydrothermal method. By using Te NWs as the sacrificial template, we demonstrate a facile and efficient method for the synthesis of PdAgTe NWs with high-quality through the partly galvanic replacement between Te NWs and the corresponding noble metal salts precursors in an aqueous solution. The compositions of PdAgTe NWs can be tuned by simply altering the concentration of the precursors. After cyclic voltammetry treatment, multi-component PdAgTe NW with a highly active and stable surface can be obtained. The structure and composition of the as-prepared nanomaterials are analyzed by transmission electron microscope, X-ray diffraction, energy dispersive X-ray spectroscopy, inductively coupled plasma-mass spectroscopy and X-ray photoelectron spectroscopy. Electrochemical catalytic measurement results prove that the as synthesized PdAgTe NWs present superior catalytic activity toward ethanol electrooxidation in alkaline solution than the commercial Pd/C catalyst, which making them can be used as effective catalysts for the direct ethanol fuel cells.

Photometry of symbiotic stars. XI. EG And, Z And, BF Cyg, CH Cyg, CI Cyg, V1329 Cyg, TX CVn, AG Dra, RW Hya, AR Pav, AG Peg, AX Per, QW Sge, IV Vir and the LMXB V934 Her

NASA Astrophysics Data System (ADS)

Skopal, A.; Pribulla, T.; Vaňko, M.; Velič, Z.; Semkov, E.; Wolf, M.; Jones, A.

2004-02-01

We present new photometric observations of EG And, Z And, BF Cyg, CH Cyg, CI Cyg, V1329 Cyg, TX CVn, AG Dra, RW Hya, AG Peg, AX Per, IV Vir and the peculiar M giant V934 Her, which were made in the standard Johnson UBV(R) system. QW Sge was measured in the Kron-Cousin B, V, RC, IC system and for AR Pav we present its new visual estimates. The current issue gathers observations of these objects to December 2003. The main results can be summarized as follows: EG And: The primary minimum in the U light curve (LC) occurred at the end of 2002. A 0.2 -- 0.3 mag brightening in U was detected in the autumn of 2003. Z And: At around August 2002 we detected for the first time a minimum, which is due to eclipse of the active object by the red giant. Measurements from 2003.3 are close to those of a quiescent phase. BF Cyg: In February 2003 a short-term flare developed in the LC. A difference in the depth of recent minima was detected. CH Cyg: This star was in a quiescent phase at a rather bright state. A shallow minimum occurred at ˜ JD 2 452 730, close to the position of the inferior conjunction of the giant in the inner binary of the triple-star model of CH Cyg. CI Cyg: Our observations cover the descending branch of a broad minimum. TX CVn: At/around the beginning of 2003 the star entered a bright stage containing a minimum at ˜ JD 2 452 660. AG Dra: New observations revealed two eruptions, which peaked in October 2002 and 2003 at ˜ 9.3 in U. AR Pav: Our new visual estimates showed a transient disappearance of a wave-like modulation in the star's brightness between the minima at epochs E = 66 and E = 68 and its reappearance. AG Peg: Our measurements from the end of 2001 showed rather complex profile of the LC. RW Hya: Observations follow behaviour of the wave-like variability of quiet symbiotics. AX Per: In May 2003 a 0.5 mag flare was detected following a rapid decrease of the light to a minimum. QW Sge: CCD observations in B, V, RC, IC bands cover a period from 1994

Photometry of symbiotic stars. X. EG And, Z And, BF Cyg, CH Cyg, V1329 Cyg, AG Dra, RW Hya, AX Per and IV Vir

NASA Astrophysics Data System (ADS)

Skopal, A.; Vanko, M.; Pribulla, T.; Wolf, M.; Semkov, E.; Jones, A.

2002-04-01

We present new photometric observations of EG And, Z And, BF Cyg, CH Cyg, V1329 Cyg, AG Dra, RW Hya, AX Per and IV Vir made in the standard Johnson UBVR system. The current issue summarizes observations of these objects to 2001 December. The main results can be summarized as follows: EG And: A periodic double-wave variation in all bands as a function of the orbital phase was confirmed. A maximum of the light changes was observed in U (Delta U ~ 0.5 mag). Z And: Our observations cover an active phase, which peaked around 8.4 in U at the beginning of 2000 December. Consequently, a gradual decrease in the star's brightness has been observed. BF Cyg: A periodic wave-like variation in the optical continuum reflects a quiescent phase of this star. A complex light curve (LC) profile was observed. CH Cyg: The recent episode of activity ended in Spring 2000. We determined the position of an eclipse in the outer binary at JD 2451426 +/- 3. Recent observations indicate a slow increase in the star's brightness. V1329 Cyg: Observations were made around a maximum at 2001.2. AG Dra: Our measurements from the Autumn of 2001 revealed a new eruption, which peaked at ~JD 2452217. RW Hya: The light minimum in our mean visual LC precedes the time of the spectroscopic conjunction of the giant in the binary. AX Per: A periodic wave-like variation was observed. Our recent observations revealed a secondary minimum at the orbital phase 0.5, seen best in the V and B bands. IV Vir: The LC displays a double-wave throughout the orbital cycle.

Improved performance of inkjet-printed Ag source/drain electrodes for organic thin-film transistors by overcoming the coffee ring effects

NASA Astrophysics Data System (ADS)

Liu, Cheng-Fang; Lin, Yan; Lai, Wen-Yong; Huang, Wei

2017-11-01

Inkjet printing is a promising technology for the scalable fabrication of organic electronics because of the material conservation and facile patterning as compared with other solution processing techniques. In this study, we have systematically investigated the cross-sectional profile control of silver (Ag) electrode via inkjet printing. A facile methodology for achieving inkjet-printed Ag source/drain with improved profiles is developed. It is demonstrated that the printing conditions such as substrate temperature, drop spacing and printing layers affect the magnitude of the droplet deposition and the rate of evaporation, which can be optimized to greatly reduce the coffee ring effects for improving the inkjet-printed electrode profiles. Ag source/drain electrodes with uniform profiles were successfully inkjet-printed and incorporated into organic thin-film transistors (OTFTs). The resulting devices showed superior electrical performance than those without special treatments. It is noted to mention that the strategy for modulating the inkjet-printed Ag electrodes in this work does not demand the ink formulation or complicated steps, which is beneficial for scaling up the printing techniques for potential large-area/mass manufacturing.

ChIP-chip versus ChIP-seq: Lessons for experimental design and data analysis

PubMed Central

2011-01-01

Background Chromatin immunoprecipitation (ChIP) followed by microarray hybridization (ChIP-chip) or high-throughput sequencing (ChIP-seq) allows genome-wide discovery of protein-DNA interactions such as transcription factor bindings and histone modifications. Previous reports only compared a small number of profiles, and little has been done to compare histone modification profiles generated by the two technologies or to assess the impact of input DNA libraries in ChIP-seq analysis. Here, we performed a systematic analysis of a modENCODE dataset consisting of 31 pairs of ChIP-chip/ChIP-seq profiles of the coactivator CBP, RNA polymerase II (RNA PolII), and six histone modifications across four developmental stages of Drosophila melanogaster. Results Both technologies produce highly reproducible profiles within each platform, ChIP-seq generally produces profiles with a better signal-to-noise ratio, and allows detection of more peaks and narrower peaks. The set of peaks identified by the two technologies can be significantly different, but the extent to which they differ varies depending on the factor and the analysis algorithm. Importantly, we found that there is a significant variation among multiple sequencing profiles of input DNA libraries and that this variation most likely arises from both differences in experimental condition and sequencing depth. We further show that using an inappropriate input DNA profile can impact the average signal profiles around genomic features and peak calling results, highlighting the importance of having high quality input DNA data for normalization in ChIP-seq analysis. Conclusions Our findings highlight the biases present in each of the platforms, show the variability that can arise from both technology and analysis methods, and emphasize the importance of obtaining high quality and deeply sequenced input DNA libraries for ChIP-seq analysis. PMID:21356108

Facile one-pot synthesis of flower-like AgCl microstructures and enhancing of visible light photocatalysis

PubMed Central

2013-01-01

Flower-like AgCl microstructures with enhanced visible light-driven photocatalysis are synthesized by a facile one-pot hydrothermal process for the first time. The evolution process of AgCl from dendritic structures to flower-like octagonal microstructures is investigated quantitatively. Furthermore, the flower-like AgCl microstructures exhibit enhanced ability of visible light-assisted photocatalytic degradation of methyl orange. The enhanced photocatalytic activity of the flower-like AgCl microstructure is attributed to its three-dimensional hierarchical structure exposing with [100] facets. This work provides a fresh view into the insight of electrochemical process and the application area of visible light photocatalysts. PMID:24153176

Gene expression profiles associated with depression in patients with chronic hepatitis C (CH-C)

PubMed Central

Birerdinc, Aybike; Afendy, Arian; Stepanova, Maria; Younossi, Issah; Baranova, Ancha; Younossi, Zobair M

2012-01-01

The standard treatment for CH-C, pegylated interferon-α and ribavirin (PEG-IFN + RBV), is associated with depression. Recent studies have proposed a new role for cytokines in the pathogenesis of depression. We aimed to assess differential gene expression related to depression in CH-C patients treated with PEG-IFN + RBV. We included 67 CH-C patients being treated with PEG-IFN+RBV. Of the entire study cohort, 22% had pre-existing depression, while another 37% developed new depression in course of the treatment. Pretreatment blood samples were collected into PAXgene™ RNA tubes, the RNAs extracted from peripheral blood mononuclear cells (PBMCs) were used for one step RT-PCR to profile 160 mRNAs. Differentially expressed genes were separated into up- and down-regulated genes according to presence or absence of depression at baseline (pre-existing depression) or following the initiation of treatment (treatment-related depression). The mRNA expression profile associated with any depression and with treatment-related depression included four and six genes, respectively. Our data demonstrate a significant down-regulation of TGF-β1 and the shift of Th1-Th2 cytokine balance in the depression associated with IFN-based treatment of HCV infection. We propose that TGF-β1 plays an important role in the imbalance of Th1/Th2 in patients with CH-C and depression. With further validation, TGF-β1 and other components of Th1/Th2 regulation pathway may provide a future marker for CH-C patients predisposed to depression. PMID:23139898

Gene expression profiles associated with depression in patients with chronic hepatitis C (CH-C).

PubMed

Birerdinc, Aybike; Afendy, Arian; Stepanova, Maria; Younossi, Issah; Baranova, Ancha; Younossi, Zobair M

2012-09-01

The standard treatment for CH-C, pegylated interferon-α and ribavirin (PEG-IFN + RBV), is associated with depression. Recent studies have proposed a new role for cytokines in the pathogenesis of depression. We aimed to assess differential gene expression related to depression in CH-C patients treated with PEG-IFN + RBV. We included 67 CH-C patients being treated with PEG-IFN+RBV. Of the entire study cohort, 22% had pre-existing depression, while another 37% developed new depression in course of the treatment. Pretreatment blood samples were collected into PAXgene™ RNA tubes, the RNAs extracted from peripheral blood mononuclear cells (PBMCs) were used for one step RT-PCR to profile 160 mRNAs. Differentially expressed genes were separated into up- and down-regulated genes according to presence or absence of depression at baseline (pre-existing depression) or following the initiation of treatment (treatment-related depression). The mRNA expression profile associated with any depression and with treatment-related depression included four and six genes, respectively. Our data demonstrate a significant down-regulation of TGF-β1 and the shift of Th1-Th2 cytokine balance in the depression associated with IFN-based treatment of HCV infection. We propose that TGF-β1 plays an important role in the imbalance of Th1/Th2 in patients with CH-C and depression. With further validation, TGF-β1 and other components of Th1/Th2 regulation pathway may provide a future marker for CH-C patients predisposed to depression.

Ag{sub 2}O/Ag{sub 3}VO{sub 4}/Ag{sub 4}V{sub 2}O{sub 7} heterogeneous photocatalyst prepared by a facile hydrothermal synthesis with enhanced photocatalytic performance under visible light irradiation

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

Ran, Rong; McEvoy, Joanne Gamage; Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, Ontario, K1N 6N5

Highlights: • The photocatalyst was hydrothermally prepared by adjusting the ratio of Ag to V. • Multi-phase Ag{sub 2}O/Ag{sub 3}VO{sub 4}/Ag{sub 4}V{sub 2}O{sub 7} obtained exhibited multi-morphological features. • The photocatalyst exhibited strong visible light driven photoactivity towards RhB. - Abstract: A novel Ag{sub 2}O/Ag{sub 3}VO{sub 4}/Ag{sub 4}V{sub 2}O{sub 7} photocatalyst was synthesized by adjusting the molar ratio of silver–vanadium (Ag–V) in a facile hydrothermal method to obtain multi-phase Ag{sub 2}O/Ag{sub 3}VO{sub 4}/Ag{sub 4}V{sub 2}O{sub 7} photocatalyst. The photocatalytic activity of the prepared samples was quantified by the degradation of Rhodamine B (RhB) model organic pollutant under visible light irradiation.more » Compared to pure Ag{sub 3}VO{sub 4}, Ag{sub 4}V{sub 2}O{sub 7} and P25 TiO{sub 2}, respectively, the as-synthesized multi-phase Ag{sub 2}O/Ag{sub 3}VO{sub 4}/Ag{sub 4}V{sub 2}O{sub 7} powders gave rise to a significantly higher photocatalytic activity, achieving up to 99% degradation of RhB in 2 h under visible light. This enhanced photocatalytic performance was attributed to the effect of the multi-phase Ag{sub 2}O/Ag{sub 3}VO{sub 4}/Ag{sub 4}V{sub 2}O{sub 7} photocatalyst and the surface plasmon resonance (SPR) of the incorporated metallic silver (Ag{sup 0}) nanoparticles (NPs) generated during the photocatalysis, as evidenced by post-use characterization, resulting in improved visible light absorption and electron-hole (e{sup −}-h{sup +}) separation. A mechanism was proposed for the photocatalytic degradation of RhB on the surface of Ag{sub 2}O/Ag{sub 3}VO{sub 4}/Ag{sub 4}V{sub 2}O{sub 7}.« less

Facile solvothermal synthesis of cube-like Ag@AgCl: a highly efficient visible light photocatalyst

NASA Astrophysics Data System (ADS)

Han, Lei; Wang, Ping; Zhu, Chengzhou; Zhai, Yueming; Dong, Shaojun

2011-07-01

In this paper, a stable and highly efficient plasmonic photocatalyst, Ag@AgCl, with cube-like morphology, has been successfully prepared via a simple hydrothermal method. Using methylene dichloride as chlorine source in the synthesis can efficiently control the morphology of Ag@AgCl, due to the low release rate of chloride ions. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra were used to characterize the obtained product. The photocatalytic activity of the obtained product was evaluated by the photodegradation of methyl orange (MO) under visible light irradiation, and it was found, interestingly, that Ag@AgCl exhibits high visible light photocatalytic activity and good stability.In this paper, a stable and highly efficient plasmonic photocatalyst, Ag@AgCl, with cube-like morphology, has been successfully prepared via a simple hydrothermal method. Using methylene dichloride as chlorine source in the synthesis can efficiently control the morphology of Ag@AgCl, due to the low release rate of chloride ions. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra were used to characterize the obtained product. The photocatalytic activity of the obtained product was evaluated by the photodegradation of methyl orange (MO) under visible light irradiation, and it was found, interestingly, that Ag@AgCl exhibits high visible light photocatalytic activity and good stability. Electronic supplementary information (ESI) available: SEM images of the AgCl samples synthesized by changing the addition amount of PVP and AgNO3. See DOI: 10.1039/c1nr10247h

Harmonisation and diagnostics of MIPAS ESA CH4 and N2O profiles using data assimilation

NASA Astrophysics Data System (ADS)

Errera, Quentin; Ceccherini, Simone; Christophe, Yves; Chabrillat, Simon; Hegglin, Michaela I.; Lambert, Alyn; Ménard, Richard; Raspollini, Piera; Skachko, Sergey; van Weele, Michiel; Walker, Kaley A.

2016-12-01

This paper discusses assimilation experiments of methane (CH4) and nitrous oxide (N2O) profiles retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Here we focus on data versions 6 and 7 provided by the ESA processor. These data sets have been assimilated by the Belgian Assimilation System for Chemical ObsErvations (BASCOE). The CH4 and N2O retrieved profiles can oscillate, especially in the tropical lower stratosphere. Using the averaging kernels of the observations and a background error covariance matrix, which has previously been calibrated, allows the system to partly remedy this issue and provide assimilated fields that are more regular vertically. In general, there is a good agreement between the BASCOE analyses and independent observations from ACE-FTS (CH4 and N2O) and MLS (N2O), demonstrating the general good quality of CH4 and N2O retrievals provided by MIPAS ESA. Nevertheless, this study also identifies two issues in these data sets. First, time series of the observations show unexpected discontinuities due to an abrupt change in the gain of MIPAS band B, generally occurring after the instrument decontamination. Since the calibration is performed weekly, the abrupt change in the gain affects the measurements until the subsequent calibration is performed. Second, the correlations between BASCOE analyses and independent observations are poor in the lower stratosphere, especially in the tropics, probably due to the presence of outliers in the assimilated data. In this region, we recommend using MIPAS CH4 and N2O retrievals with caution.

Facile one-step synthesis of Ag@Fe3O4 core-shell nanospheres for reproducible SERS substrates

NASA Astrophysics Data System (ADS)

Sun, Lijuan; He, Jiang; An, Songsong; Zhang, Junwei; Ren, Dong

2013-08-01

A facile approach has been developed to synthesize Ag@Fe3O4 core-shell nanospheres, in which the Ag nanoparticle core was well wrapped by a permeable Fe3O4 shell. An in situ reduction of AgNO3 and Fe(NO3)3 was the basis of this one-step method with ethylene glycol as the reducing agent. The as-obtained Ag@Fe3O4 nanospheres were a highly efficient surface-enhanced Raman scattering (SERS) substrate; high reproducibility, stability, and reusability were obtained by employing 4-aminothiophenol (4-ATP) and rhodamine 6G (R6G) as the Raman probe molecules. It was revealed that the SERS signals of 4-ATP and R6G on the Ag@Fe3O4 nanospheres were much stronger than those on the pure Ag nanoparticles, demonstrating that the magnetic enrichment procedures can improve SERS detection sensitivity efficiently. A highly efficient and recyclable SERS substrate was produced by the new model system that has potential applications in chemical and biomolecular assays.

Seasonality and interannual variability of CH4 fluxes from the eastern Amazon Basin inferred from atmospheric mole fraction profiles.

PubMed

Basso, Luana S; Gatti, Luciana V; Gloor, Manuel; Miller, John B; Domingues, Lucas G; Correia, Caio S C; Borges, Viviane F

2016-01-16

The Amazon Basin is an important region for global CH 4 emissions. It hosts the largest area of humid tropical forests, and around 20% of this area is seasonally flooded. In a warming climate it is possible that CH 4 emissions from the Amazon will increase both as a result of increased temperatures and precipitation. To examine if there are indications of first signs of such changes we present here a 13 year (2000-2013) record of regularly measured vertical CH 4 mole fraction profiles above the eastern Brazilian Amazon, sensitive to fluxes from the region upwind of Santarém (SAN), between SAN and the Atlantic coast. Using a simple mass balance approach, we find substantial CH 4 emissions with an annual average flux of 52.8 ± 6.8 mg CH 4 m -2  d -1 over an area of approximately 1 × 10 6  km 2 . Fluxes are highest in two periods of the year: in the beginning of the wet season and during the dry season. Using a CO:CH 4 emission factor estimated from the profile data, we estimated a contribution of biomass burning of around 15% to the total flux in the dry season, indicating that biogenic emissions dominate the CH 4 flux. This 13 year record shows that CH 4 emissions upwind of SAN varied over the years, with highest emissions in 2008 (around 25% higher than in 2007), mainly during the wet season, representing 19% of the observed global increase in this year.

Seasonality and interannual variability of CH4 fluxes from the eastern Amazon Basin inferred from atmospheric mole fraction profiles

PubMed Central

Gatti, Luciana V.; Gloor, Manuel; Miller, John B.; Domingues, Lucas G.; Correia, Caio S. C.; Borges, Viviane F.

2016-01-01

Abstract The Amazon Basin is an important region for global CH4 emissions. It hosts the largest area of humid tropical forests, and around 20% of this area is seasonally flooded. In a warming climate it is possible that CH4 emissions from the Amazon will increase both as a result of increased temperatures and precipitation. To examine if there are indications of first signs of such changes we present here a 13 year (2000–2013) record of regularly measured vertical CH4 mole fraction profiles above the eastern Brazilian Amazon, sensitive to fluxes from the region upwind of Santarém (SAN), between SAN and the Atlantic coast. Using a simple mass balance approach, we find substantial CH4 emissions with an annual average flux of 52.8 ± 6.8 mg CH4 m−2 d−1 over an area of approximately 1 × 106 km2. Fluxes are highest in two periods of the year: in the beginning of the wet season and during the dry season. Using a CO:CH4 emission factor estimated from the profile data, we estimated a contribution of biomass burning of around 15% to the total flux in the dry season, indicating that biogenic emissions dominate the CH4 flux. This 13 year record shows that CH4 emissions upwind of SAN varied over the years, with highest emissions in 2008 (around 25% higher than in 2007), mainly during the wet season, representing 19% of the observed global increase in this year. PMID:27642546

ChIP-seq and ChIP-exo profiling of Pol II, H2A.Z, and H3K4me3 in human K562 cells.

PubMed

Mchaourab, Zenab F; Perreault, Andrea A; Venters, Bryan J

2018-03-06

The human K562 chronic myeloid leukemia cell line has long served as an experimental paradigm for functional genomic studies. To systematically and functionally annotate the human genome, the ENCODE consortium generated hundreds of functional genomic data sets, such as chromatin immunoprecipitation coupled to sequencing (ChIP-seq). While ChIP-seq analyses have provided tremendous insights into gene regulation, spatiotemporal insights were limited by a resolution of several hundred base pairs. ChIP-exonuclease (ChIP-exo) is a refined version of ChIP-seq that overcomes this limitation by providing higher precision mapping of protein-DNA interactions. To study the interplay of transcription initiation and chromatin, we profiled the genome-wide locations for RNA polymerase II (Pol II), the histone variant H2A.Z, and the histone modification H3K4me3 using ChIP-seq and ChIP-exo. In this Data Descriptor, we present detailed information on parallel experimental design, data generation, quality control analysis, and data validation. We discuss how these data lay the foundation for future analysis to understand the relationship between the occupancy of Pol II and nucleosome positions at near base pair resolution.

Facile One-Step Sonochemical Synthesis and Photocatalytic Properties of Graphene/Ag3PO4 Quantum Dots Composites

NASA Astrophysics Data System (ADS)

Reheman, Abulajiang; Tursun, Yalkunjan; Dilinuer, Talifu; Halidan, Maimaiti; Kadeer, Kuerbangnisha; Abulizi, Abulikemu

2018-03-01

In this study, a novel graphene/Ag3PO4 quantum dot (rGO/Ag3PO4 QD) composite was successfully synthesized via a facile one-step photo-ultrasonic-assisted reduction method for the first time. The composites were analyzed by various techniques. According to the obtained results, Ag3PO4 QDs with a size of 1-4 nm were uniformly dispersed on rGO nanosheets to form rGO/Ag3PO4 QD composites. The photocatalytic activity of rGO/Ag3PO4 QD composites was evaluated by the decomposition of methylene blue (MB). Meanwhile, effects of the surfactant dosage and the amount of rGO on the photocatalytic activity were also investigated. It was found that rGO/Ag3PO4 QDs (WrGO:Wcomposite = 2.3%) composite exhibited better photocatalytic activity and stability with degrading 97.5% of MB within 5 min. The improved photocatalytic activities and stabilities were majorly related to the synergistic effect between Ag3PO4 QDs and rGO with high specific surface area, which gave rise to efficient interfacial transfer of photogenerated electrons and holes on both materials. Moreover, possible formation and photocatalytic mechanisms of rGO/Ag3PO4 QDs were proposed. The obtained rGO/Ag3PO4 QDs photocatalysts would have great potentials in sewage treatment and water splitting.

Sequential ChIP Protocol for Profiling Bivalent Epigenetic Modifications (ReChIP).

PubMed

Desvoyes, Bénédicte; Sequeira-Mendes, Joana; Vergara, Zaida; Madeira, Sofia; Gutierrez, Crisanto

2018-01-01

Identification of chromatin modifications, e.g., histone acetylation and methylation, among others, is widely carried out by using a chromatin immunoprecipitation (ChIP) strategy. The information obtained with these procedures is useful to gain an overall picture of modifications present in all cells of the population under study. It also serves as a basis to figure out the mechanisms of chromatin organization and gene regulation at the population level. However, the ultimate goal is to understand gene regulation at the level of single chromatin fibers. This requires the identification of chromatin modifications that occur at a given genomic location and within the same chromatin fiber. This is achieved by following a sequential ChIP strategy using two antibodies to distinguish different chromatin modifications. Here, we describe a sequential ChIP protocol (Re-ChIP), paying special attention to the controls needed and the required steps to obtain meaningful and reproducible results. The protocol is developed for young Arabidopsis seedlings but could be adapted to other plant materials.

Negligible shift of 3Ag- potential in longer-chain carotenoids as revealed by a single persistent peak of 3Ag-→1Ag- stimulated emission followed by 3Ag-←1Ag- transient-absorption

NASA Astrophysics Data System (ADS)

Li, Chunyong; Miki, Takeshi; Kakitani, Yoshinori; Koyama, Yasushi; Nagae, Hiroyoshi

2007-12-01

Upon excitation of lycopene, anhydrorhodovibrin or spirilloxanthin to the 1Bu+(0) state, stimulated emission followed by transient-absorption was observed as a single peak with the 3Ag-(0) energy that had been determined by measurement of resonance-Raman excitation profiles. This observation was explained in terms of negligible shift of the 3Ag- potential, in reference to the 1Ag- potential, where only the 3Ag-(υ)→1Ag-(υ) emission and the 3Ag-(υ)←1Ag-(υ) absorption become allowed during the vibrational relaxation of υ = 2 → 1 → 0, starting from the 3Ag-(2) level generated by diabatic internal conversion from the 1Bu+(0) level, in anhydrorhodovibrin, for example.

Longitudinal profiles of highly sensitive hepatitis B surface antigen levels: re-evaluation of HBsAg seroclearance.

PubMed

Seto, Wai-Kay; Tanaka, Yasuhito; Wong, Danny K-H; Shinkai, Noboru; Cheung, Ka-Shing; Liu, Kevin S-H; Fung, James; Lai, Ching-Lung; Yuen, Man-Fung

2016-05-01

Serologic profiles after hepatitis B surface antigen (HBsAg) seroclearance in chronic hepatitis B (CHB) have not been well-studied. We employed a highly sensitive HBsAg (hs-HBsAg) assay (lower detection limit 0.5 mIU/ml), 100 times more sensitive than conventional HBsAg measurements. CHB patients achieving HBsAg seroclearance defined by conventional assays were followed up for serum hs-HBsAg, HBV DNA and antibody to HBsAg (anti-HBs) levels at 0 months, 6-12 months and 3-5 years after HBsAg seroclearance. Factors associated with hs-HBsAg detectability were determined. One hundred and nine patients were recruited; 94 (86.2%) were followed up to years 3-5; and 25 patients (22.9%) were on nucleoside analogue therapy for a median duration of 6.0 (range 1.5-12.7) years before HBsAg seroclearance. Detectable hs-HBsAg was noted in 88 (80.7%), 60 (55.0%) and 20 (21.3%) patients at 0 months, 6-12 months and 3-5 years respectively. At years 3-5, genotype B patients, when compared to genotype C patients, had a higher anti-HBs positive rate (63.2% and 41.1% respectively, P = 0.036). Serum anti-HBs positivity, when compared to persistent anti-HBs negativity, was associated with a lower rate of hs-HBsAg detection (7.4% and 40% respectively, P < 0.001). Multivariate analysis showed anti-HBs negativity at years 3-5 to be independently associated with persistently positive hs-HBsAg (P = 0.007, odds ratio 7.1, 95% confidence interval 1.7-29.3). Serum hs-HBsAg could detect HBsAg presence in a substantial proportion of CHB after HBsAg seroclearance defined by conventional assays, especially among anti-HBs negative individuals. Serum hs-HBsAg could potentially assist differentiating HBsAg-negative CHB from individuals with only past HBV exposure without carrier state. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

World Energy Data System (WENDS). Volume X. Nuclear facility profiles, PO--ZA. [Brief tabulated information

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

Not Available

1979-06-01

In this compendium each profile of a nuclear facility is a capsule summary of pertinent facts regarding that particular installation. The facilities described include the entire fuel cycle in the broadest sense, encompassing resource recovery through waste management. Power plants and all US facilities have been excluded. To facilitate comparison the profiles have been recorded in a standard format. Because of the breadth of the undertaking some data fields do not apply to the establishment under discussion and accordingly are blank. The set of nuclear facility profiles occupies four volumes; the profiles are ordered by country name, and then bymore » facility code. Each nuclear facility profile volume contains two complete indexes to the information. The first index aggregates the facilities alphabetically by country. It is further organized by category of facility, and then by the four-character facility code. It provides a quick summary of the nuclear energy capability or interest in each country and also an identifier, the facility code, which can be used to access the information contained in the profile.« less

Fluxes of CO2, CH4 and N2O at two European beech forests: linking soil gas production profiles with soil and stem fluxes

NASA Astrophysics Data System (ADS)

Maier, Martin; Machacova, Katerina; Halaburt, Ellen; Haddad, Sally; Urban, Otmar; Lang, Friederike

2016-04-01

Soil and plant surfaces are known to exchange greenhouse gases with the atmosphere. Some gases like nitrous oxide (N2O) and methane (CH4) can be produced and re-consumed in different soil depths and soil compartments, so that elevated concentrations of CH4 or N2O in the soil do not necessarily mean a net efflux from the soil into the atmosphere. Soil aeration, and thus the oxygen status can underlay a large spatial variability within the soil on the plot and profile scale, but also within soil aggregates. Thus, conditions suitable for production and consumption of CH4 and N2O can vary on different scales in the soil. Plant surfaces can also emit or take up CH4 and N2O, and these fluxes can significantly contribute to the net ecosystem exchange. Since roots usually have large intercellular spaces or aerenchyma they may represent preferential transport ways for soil gases, linking possibly elevated soil gas concentrations in the subsoil in a "shortcut" to the atmosphere. We tested the hypothesis that the spatial variability of the soil-atmosphere fluxes of CO2, CH4 and N2O is caused by the heterogeneity in soil properties. Therefore, we measured soil-atmosphere gas fluxes, soil gas concentrations and soil diffusivity profiles and did a small scale field assessment of soil profiles on the measurments plots. We further tried to link vertical profiles of soil gas concentrations and diffusivity to derive the production and consumption profiles, and to link these profiles to the stem-atmosphere flux rates of individual trees. Measurements were conducted in two mountain beech forests with different geographical and climatic conditions (White Carpathians, Czech Republic; Black Forest, Germany). Gas fluxes at stem and soil levels were measured simultaneously using static chamber systems and chromatographic and continuous laser analyses. Monitoring simultaneously vertical soil gas profiles allowed to assess the within-soil gas fluxes, and thus to localize the production and

BloodChIP: a database of comparative genome-wide transcription factor binding profiles in human blood cells.

PubMed

Chacon, Diego; Beck, Dominik; Perera, Dilmi; Wong, Jason W H; Pimanda, John E

2014-01-01

The BloodChIP database (http://www.med.unsw.edu.au/CRCWeb.nsf/page/BloodChIP) supports exploration and visualization of combinatorial transcription factor (TF) binding at a particular locus in human CD34-positive and other normal and leukaemic cells or retrieval of target gene sets for user-defined combinations of TFs across one or more cell types. Increasing numbers of genome-wide TF binding profiles are being added to public repositories, and this trend is likely to continue. For the power of these data sets to be fully harnessed by experimental scientists, there is a need for these data to be placed in context and easily accessible for downstream applications. To this end, we have built a user-friendly database that has at its core the genome-wide binding profiles of seven key haematopoietic TFs in human stem/progenitor cells. These binding profiles are compared with binding profiles in normal differentiated and leukaemic cells. We have integrated these TF binding profiles with chromatin marks and expression data in normal and leukaemic cell fractions. All queries can be exported into external sites to construct TF-gene and protein-protein networks and to evaluate the association of genes with cellular processes and tissue expression.

AgHalo: A Facile Fluorogenic Sensor to Detect Drug-Induced Proteome Stress.

PubMed

Liu, Yu; Fares, Matthew; Dunham, Noah P; Gao, Zi; Miao, Kun; Jiang, Xueyuan; Bollinger, Samuel S; Boal, Amie K; Zhang, Xin

2017-07-17

Drug-induced proteome stress that involves protein aggregation may cause adverse effects and undermine the safety profile of a drug. Safety of drugs is regularly evaluated using cytotoxicity assays that measure cell death. However, these assays provide limited insights into the presence of proteome stress in live cells. A fluorogenic protein sensor is reported to detect drug-induced proteome stress prior to cell death. An aggregation prone Halo-tag mutant (AgHalo) was evolved to sense proteome stress through its aggregation. Detection of such conformational changes was enabled by a fluorogenic ligand that fluoresces upon AgHalo forming soluble aggregates. Using 5 common anticancer drugs, we exemplified detection of differential proteome stress before any cell death was observed. Thus, this sensor can be used to evaluate drug safety in a regime that the current cytotoxicity assays cannot cover and be generally applied to detect proteome stress induced by other toxins. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facile synthesis of dispersed Ag nanoparticles on chitosan-TiO2 composites as recyclable nanocatalysts for 4-nitrophenol reduction

NASA Astrophysics Data System (ADS)

Xiao, Gang; Zhao, Yilin; Li, Linghui; Pratt, Jonathan O.; Su, Haijia; Tan, Tianwei

2018-04-01

This paper presents a facile, rapid, and controllable procedure for the recovery of trace Ag+ ions and in situ assembly of well dispersed Ag nanoparticles on chitosan-TiO2 composites through bioaffinity adsorption followed by photocatalytic reduction. The prepared Ag nanoparticles are proven to be efficient and recyclable nanocatalysts for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. Well dispersed quasi-spherical Ag NPs are synthesized in 20 min in the designed inner-irradiated photocatalytic system under a wide range of Ag+ concentrations (50-200 mg l-1), temperatures (10 °C-25 °C) conditions, and UV or visible light irradiation. The synthesized Ag NPs can catalyze the reduction of 4-nitrophenol by NaBH4 at 100% conversion in 120 min and preserve the catalytic activity in five successive cycles. This procedure for trace Ag+ ions recovery and Ag NPs assembly has the potential to be scaled up for the mass production of recyclable Ag nanocatalysts. The present work provides a green and efficient procedure for the conversion of hazardous 4-nitrophenol to industrially important 4-aminophenol and also sheds a light on designing scaled-up procedures for treating high volumes of wastewater with dilute heavy metals to produce recyclable metallic nanocatalysts in aqueous systems.

Facile and eco-friendly fabrication of AgNPs coated silk for antibacterial and antioxidant textiles using honeysuckle extract.

PubMed

Zhou, Yuyang; Tang, Ren-Cheng

2018-01-01

Recently, there is a growing trend towards the functionalization of silk through nanotechnology for the prevention of fiber damage from microbial attack and the enhancement of hygienic aspects. Considering sustainable development and environmental protection, the eco-friendly fabrication of silver nanoparticles (AgNPs)-modified silk using natural extracts has currently become a hot research area. This study presents a facile strategy for the fabrication of colorful and multifunctional silk fabric using biogenic AgNPs prepared by honeysuckle extract as natural reductant and stabilizing agents. The influences of pH and reactant concentrations on the AgNPs synthesis were investigated. The color characteristics and functionalities of AgNPs treated silk were evaluated. The results revealed that the particle size of AgNPs decreased with increasing pH. The diameter of AgNPs decreased with increasing amount of honeysuckle extract and reducing amount of silver nitrate. The transmission electron microscopy image showed that the AgNPs were spherical in shape with a narrow size distribution. The treated silk showed excellent antibacterial activities against E. coli and S. aureus, and certain antioxidant activity. Both of the antibacterial and antioxidant activities were well maintained even after 30 washing cycles. This work provides a sustainable and eco-friendly approach to the fabrication of AgNPs coated silk for colorful and long-term multifunctional textiles using honeysuckle extract. Copyright © 2017 Elsevier B.V. All rights reserved.

Facile fabrication of high-quality Ag/PS coaxial nanocables based on the mixed mode of soft/hard templates

PubMed Central

Wan, Mimi; Zhao, Wenbo; Peng, Fang; Wang, Qi; Xu, Ping; Mao, Chun; Shen, Jian

2016-01-01

A new kind of high-quality Ag/PS coaxial nanocables can be facilely synthesized by using soft/hard templates method. In order to effectively introduce Ag sources into porous polystyrene (PS) nanotubes which were trapped in porous anodic aluminum oxide (AAO) hard template, Pluronic F127 (F127) was used as guiding agent, soft template and reductant. Meanwhile, ethylene glycol solution was also used as solvent and co-reducing agent to assist in the formation of silver nanowires. The influences of concentration of F127 and reducing reaction time on the formation of Ag/PS coaxial nanocables were discussed. Results indicated that the high-quality Ag/PS coaxial nanocables can be obtained by the mixed mode of soft/hard templates under optimized conditions. This strategy is expected to be extended to design more metal/polymer coaxial nanocables for the benefit of creation of complex and functional nanoarchitectures and components. PMID:27477888

Facile fabrication of high-quality Ag/PS coaxial nanocables based on the mixed mode of soft/hard templates

NASA Astrophysics Data System (ADS)

Wan, Mimi; Zhao, Wenbo; Peng, Fang; Wang, Qi; Xu, Ping; Mao, Chun; Shen, Jian

2016-08-01

A new kind of high-quality Ag/PS coaxial nanocables can be facilely synthesized by using soft/hard templates method. In order to effectively introduce Ag sources into porous polystyrene (PS) nanotubes which were trapped in porous anodic aluminum oxide (AAO) hard template, Pluronic F127 (F127) was used as guiding agent, soft template and reductant. Meanwhile, ethylene glycol solution was also used as solvent and co-reducing agent to assist in the formation of silver nanowires. The influences of concentration of F127 and reducing reaction time on the formation of Ag/PS coaxial nanocables were discussed. Results indicated that the high-quality Ag/PS coaxial nanocables can be obtained by the mixed mode of soft/hard templates under optimized conditions. This strategy is expected to be extended to design more metal/polymer coaxial nanocables for the benefit of creation of complex and functional nanoarchitectures and components.

Altered Baseline and Nicotine-Mediated Behavioral and Cholinergic Profiles in ChAT-Cre Mouse Lines.

PubMed

Chen, Edison; Lallai, Valeria; Sherafat, Yasmine; Grimes, Nickolas P; Pushkin, Anna N; Fowler, J P; Fowler, Christie D

2018-02-28

baseline and/or nicotine-mediated behavioral profiles were discovered in transgenic mice from the ChAT (BAC) -Cre and ChAT (IRES) -Cre lines. Given that these cre-expressing mice have become increasingly used by the scientific community, either independently with chemicogenetic and optogenetic viral vectors or crossed with other transgenic lines, the current studies highlight important considerations for the interpretation of data from previous and future experimental investigations. Moreover, the current findings detail the behavioral effects of either increased or decreased baseline cholinergic signaling mechanisms on locomotor, anxiety, learning/memory, and intravenous nicotine self-administration behaviors. Copyright © 2018 the authors 0270-6474/18/382177-12$15.00/0.

Experimental and theoretical study on activation of the C-H bond in pyridine by [M(m)]- (M = Cu, Ag, Au, m = 1-3).

PubMed

Liu, Xiao-Jing; Hamilton, I P; Han, Ke-Li; Tang, Zi-Chao

2010-09-21

Activation of the C-H bond of pyridine by [M(m)](-) (M = Cu, Ag, Au, m = 1-3) is investigated by experiment and theory. Complexes of coinage metal clusters and the pyridyl group, [M(m)-C(5)H(4)N](-), are produced from reactions between metal clusters formed by laser ablation of coinage metal samples and pyridine molecules seeded in argon carrier gas. We examine the structure and formation mechanism of these pyridyl-coinage metal complexes. Our study shows that C(5)H(4)N bonds to the metal clusters through a M-C sigma bond and [M(m)-C(5)H(4)N](-) is produced via a stepwise mechanism. The first step is a direct insertion reaction between [M(m)](-) and C(5)H(5)N with activation of the C-H bond to yield the intermediate [HM(m)-C(5)H(4)N](-). The second step is H atom abstraction by a neutral metal atom to yield [M(m)-C(5)H(4)N](-).

Initial Effects of NO x on Idodine and Methyl Iodine Loading of AgZ and Aerogels

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

Bruffey, Stephanie H.; Jubin, Robert Thomas

2015-03-31

This initial evaluation provides insight into the effect of NO on the adsorption of both I 2 and CH 3I onto reduced silver-exchanged mordenite (Ag 0Z). It was determined that adsorption of CH 3I onto Ag 0Z occurs at approximately 50% of the rate of I 2 adsorption onto Ag 0Z, although total iodine capacities are comparable. Addition of 1% NO to the simulated off-gas stream results in very similar loading behaviors and iodine capacities for both iodine species. This is most likely an effect of CH 3I oxidation to I 2 by NO prior to contact with the sorbentmore » bed. Completion of tests including NO 2 in the simulated off-gas stream was delayed due to vendor NO 2 production schedules. A statistically designed test matrix is partially completed, and upon conclusion of the suggested experiments, the effects of temperature, NO, NO 2, and water vapor on the sorption of CH 3I and I 2 onto Ag 0Z will be able to be statistically resolved. This work represents progress towards that aim.« less

Aligning Ag Nanowires by a Facile Bioinspired Directional Liquid Transfer: Toward Anisotropic Flexible Conductive Electrodes.

PubMed

Meng, Lili; Bian, Ruixin; Guo, Cheng; Xu, Bojie; Liu, Huan; Jiang, Lei

2018-06-01

Recent years have witnessed the booming development of transparent flexible electrodes (TFEs) for their applications in electronics and optoelectronic devices. Various strategies have thus been developed for preparing TFEs with higher flexibility and conductivity. However, little work has focused on TFEs with anisotropic conductivity. Here, a facile strategy of directional liquid transfer is proposed, guided by a conical fibers array (CFA), based on which silver nanowires (AgNWs) are aligned on a soft poly(ethylene terephthalate) substrate in large scale. After further coating a second thin layer of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), a TFE with notable anisotropic conductivity and excellent optical transmittance of 95.2% is prepared. It is proposed that the CFA enables fine control over the receding of the three-phase contact line during the dewetting process, where AgNWs are guided and aligned by the as-generated directional stress. Moreover, anisotropic electrochemical deposition is enabled where the Cu nanoparticles deposit only on the oriented AgNWs, leading to a surface with anisotropic wetting behavior. Importantly, the approach enables alignment of AgNWs via multiple directions at one step. It is envisioned that the as-developed approach will provide an optional approach for simple and low-cost preparation of TFE with various functions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Templated-synthesis of hierarchical Ag-AgBr hollow cubes with enhanced visible-light-responsive photocatalytic activity

NASA Astrophysics Data System (ADS)

Kong, Chuncai; Ma, Bo; Liu, Ke; Pu, Fangzhao; Yang, Zhimao; Yang, Sen

2018-06-01

A facile Cu2O-templated approach is demonstrated for the synthesis of hierarchical Ag-AgBr hollow nanucubes. The structural and morphological characterizations show that the as-prepared hollow Ag-AgBr nanocubes consist of dense nanotips, which exhibited an excellent photocatalytic activity under visible light due to the strong surface plasmon resonance (SPR) of Ag nanosturctures and the synergistic effect between Ag and AgBr. The photodegradation ability was evaluated by the degradation of the methyl orange (MO) dye under visible-light irradiation, showing that more than 90% of the MO could be decomposed in 20 min.

Palladium-catalyzed C-H functionalization of acyldiazomethane and tandem cross-coupling reactions.

PubMed

Ye, Fei; Qu, Shuanglin; Zhou, Lei; Peng, Cheng; Wang, Chengpeng; Cheng, Jiajia; Hossain, Mohammad Lokman; Liu, Yizhou; Zhang, Yan; Wang, Zhi-Xiang; Wang, Jianbo

2015-04-08

Palladium-catalyzed C-H functionalization of acyldiazomethanes with aryl iodides has been developed. This reaction is featured by the retention of the diazo functionality in the transformation, thus constituting a novel method for the introduction of diazo functionality to organic molecules. Consistent with the experimental results, the density functional theory (DFT) calculation indicates that the formation of Pd-carbene species in the catalytic cycle through dinitrogen extrusion from the palladium ethyl diazoacetate (Pd-EDA) complex is less favorable. The reaction instead proceeds through Ag2CO3 assisted deprotonation and subsequently reductive elimination to afford the products with diazo functionality remained. This C-H functionalization transformation can be further combined with the recently evolved palladium-catalyzed cross-coupling reaction of diazo compounds with aryl iodides to develop a tandem coupling process for the synthesis of α,α-diaryl esters. DFT calculation supports the involvement of Pd-carbene as reactive intermediate in the catalytic cycle, which goes through facile carbene migratory insertion with a low energy barrier (3.8 kcal/mol).

Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

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

Singh, Anamika; Dutta, Dimple P., E-mail: dimpled@barc.gov.in; Ballal, A.

Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed thatmore » inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.« less

Control and performance of the AGS and AGS Booster Main Magnet Power Supplies

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

Reece, R.K.; Casella, R.; Culwick, B.

1993-06-01

Techniques for precision control of the main magnet power supplies for the AGS and AGS Booster synchrotron will be discussed. Both synchrotrons are designed to operate in a Pulse-to-Pulse Modulation (PPM) environment with a Supercycle Generator defining and distributing global timing events for the AGS Facility. Details of modelling, real-time feedback and feedforward systems, generation and distribution of real time field data, operational parameters and an overview of performance for both machines are included.

Control and performance of the AGS and AGS Booster Main Magnet Power Supplies

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

Reece, R.K.; Casella, R.; Culwick, B.

1993-01-01

Techniques for precision control of the main magnet power supplies for the AGS and AGS Booster synchrotron will be discussed. Both synchrotrons are designed to operate in a Pulse-to-Pulse Modulation (PPM) environment with a Supercycle Generator defining and distributing global timing events for the AGS Facility. Details of modelling, real-time feedback and feedforward systems, generation and distribution of real time field data, operational parameters and an overview of performance for both machines are included.

Enhanced photocatalytic performance of RGO/Ag nanocomposites produced via a facile microwave irradiation for the degradation of Rhodamine B in aqueous solution

NASA Astrophysics Data System (ADS)

Divya, K. S.; Chandran, Akash; Reethu, V. N.; Mathew, Suresh

2018-06-01

A series of RGO/Ag nanocomposites with different weight addition ratios of graphene oxide (GO) have been successfully prepared in situ through the simultaneous reduction of GO and AgNO3 via a facile microwave irradiation. X-ray diffraction analysis, Fourier Transform Infrared Spectroscopy, UV-vis diffuse reflectance spectra, Scanning electron microscopy, Photoluminescence spectra, Raman spectra, Atomic Force Microscopy, X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy are employed to determine the properties of the samples. It is found that RGO/Ag nanocomposites with a proper weight addition ratios of GO exhibit higher photocatalytic activity toward liquid phase photodegradation of Rhodamine B under visible light irradiation. The improved photoactivity of RGO/Ag nanocomposites can be ascribed to the integrative synergestic effect of enhanced adsorption capacity, the prolonged lifetime of photogenerated electron-hole pairs and effective interfacial hybridization between RGO and Ag nanoparticles. This study also shows that graphene sheets act as electronic conductive channels to efficiently separate charge carriers from Ag nanoparticles.

Efficacy of intranasal LaAg vaccine against Leishmania amazonensis infection in partially resistant C57Bl/6 mice.

PubMed

Pratti, Juliana Elena Silveira; Ramos, Tadeu Diniz; Pereira, Joyce Carvalho; da Fonseca-Martins, Alessandra Marcia; Maciel-Oliveira, Diogo; Oliveira-Silva, Gabriel; de Mello, Mirian França; Chaves, Suzana Passos; Gomes, Daniel Claudio Oliveira; Diaz, Bruno Lourenço; Rossi-Bergmann, Bartira; de Matos Guedes, Herbert Leonel

2016-10-06

We have previously demonstrated that intranasal vaccination of highly susceptible BALB/c mice with whole Leishmania amazonensis antigens (LaAg) leads to protection against murine cutaneous leishmaniasis. Here, we evaluate the response of partially resistant C57BL/6 mice to vaccination as a more representative experimental model of human cutaneous leishmaniasis. C57BL/6 mice from different animal facilities were infected with L. amazonensis (Josefa strain) to establish the profile of infection. Intranasal vaccination was performed before the infection challenge with two doses of 10 μg of LaAg alone or associated with the adjuvant ADDAVAX® by instillation in the nostrils. The lesion progression was measured with a dial caliper and the parasite load by limited dilution assay in the acute and chronic phases of infection. Cytokines were quantified by ELISA in the homogenates of infected footpads. C57BL/6 mice from different animal facilities presented the same L. amazonensis infection profile, displaying a progressive acute phase followed by a controlled chronic phase. Parasites cultured in M199 and Schneider's media were equally infective. Intranasal vaccination with LaAg led to milder acute and chronic phases of the disease. The mechanism of protection was associated with increased production of IFN-gamma in the infected tissue as measured in the acute phase. Association with the ADDAVAX® adjuvant did not improve the efficacy of intranasal LaAg vaccination. Rather, ADDAVAX® reduced vaccination efficacy. This study demonstrates that the efficacy of adjuvant-free intranasal vaccination with LaAg is extendable to the more resistant C57Bl/6 mouse model of infection with L. amazonensis, and is thus not exclusive to the susceptible BALB/c model. These results imply that mucosal immunomodulation by LaAg leads to peripheral protection irrespective of the genetic background of the host.

Helicopter Flying Qualities Characteristics-CH-46E. Volume 1

DTIC Science & Technology

1983-10-03

STABILITY 54 6.0 CONTROL SENSITIVITY 61 . ° i CONTENTS (continued) Page 7.0 TIME HISTORY DATA 65 7.1 GENERAL 65 7.2 DYNAMIC STABILITY 65 7.3 CONTROL...The CH-46E meets these requirements by comfortable margins at the conditions tested. 61 NADC-81118-60 Volume 1 CH-46E (FRB, CONTROL IESPON!SE CH-46E...0 4.- ip L% t ,. _ 5" * ,.4 ••t, EFIGURE 7-5 I 7 ----- 1 FIU- - IA2 NADC-81118-6 Volume I-- .4 . > b in Zh. JI - ag4A 19-- O e t’ c 4 a I,- t

Facile O-atom insertion into CC and CH bonds by a trinuclear copper complex designed to harness a singlet oxene

PubMed Central

Chen, Peter P.-Y.; Yang, Richard B.-G.; Lee, Jason C.-M.; Chan, Sunney I.

2007-01-01

Two trinuclear copper [CuICuICuI(L)]1+ complexes have been prepared with the multidentate ligands (L) 3,3′-(1,4-diazepane-1,4-diyl)bis(1-((2-(dimethylamino)ethyl)(methyl)amino)propan-2-ol) (7-Me) and (3,3′-(1,4-diazepane-1,4-diyl)bis(1-((2-(diethylamino) ethyl)(ethyl) amino)propan-2-ol) (7-Et) as models for the active site of the particulate methane monooxygenase (pMMO). The ligands were designed to form the proper spatial and electronic geometry to harness a “singlet oxene,” according to the mechanism previously suggested by our laboratory. Consistent with the design strategy, both [CuICuICuI(L)]1+ reacted with dioxygen to form a putative bis(μ3-oxo)CuIICuIICuIII species, capable of facile O-atom insertion across the central CC bond of benzil and 2,3-butanedione at ambient temperature and pressure. These complexes also catalyze facile O-atom transfer to the CH bond of CH3CN to form glycolonitrile. These results, together with our recent biochemical studies on pMMO, provide support for our hypothesis that the hydroxylation site of pMMO contains a trinuclear copper cluster that mediates CH bond activation by a singlet oxene mechanism. PMID:17804786

Facile synthesis of Ag/ZnO heterostructures assisted by UV irradiation: Highly photocatalytic property and enhanced photostability

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

Yang, Zhongmei, E-mail: kalimodor@163.com; Zhang, Ping; Ding, Yanhuai

2011-10-15

Highlights: {yields} Fabrication of Ag/ZnO heterostructure between the two incompatible phases is realized under UV irradiation in the absence of surfactant. {yields} The synthetic method is facile, low cost, and low carbon, which depends on the photogenerated electrons produced by ZnO under UV light. {yields} Photocatalytic property of the as-synthesized samples is 3.0 times as good as the pure ZnO synthesized under the same condition or the commercial TiO{sub 2} (Degussa, P-25). {yields} The heterostructures exhibit good durability without significant change in the activity even after the third cycle compared to the pure ZnO. -- Abstract: We report a newmore » method to synthesize Ag/ZnO heterostructures assisted by UV irradiation. The formation of Ag/ZnO heterostructures depends on photogenerated electrons produced by ZnO under UV light to reduce high valence silver. Functional property of the Ag/ZnO heterostructures is evaluated by photodegradation of methylene blue (MB) under UV illumination. Results of photodegradation tests reveal that the optimal photocatalytic activity of as-syntheszied samples is about 1.5 times higher than the pure ZnO synthesized in the same condition or commercial TiO{sub 2} (P-25), showing the advantage of the unique structure in the Ag/ZnO heterostructure. Besides, due to the reduced activation of surface oxygen atom, photocatalytic activity of the photocatalysts has no evident decrease even after three recycles.« less

Green and facile synthesis of fibrous Ag/cotton composites and their catalytic properties for 4-nitrophenol reduction

NASA Astrophysics Data System (ADS)

Li, Ziyu; Jia, Zhigang; Ni, Tao; Li, Shengbiao

2017-12-01

Natural cotton, featuring abundant oxygen-containing functional groups, has been utilized as a reductant to synthesize Ag nanoparticles on its surface. Through the facile and environment-friendly reduction process, the fibrous Ag/cotton composite (FAC) was conveniently synthesized. Various characterization techniques including XRD, XPS, TEM, SEM, EDS and FT-IR had been utilized to study the material microstructure and surface properties. The resulting FAC exhibited favorable activity on the catalytic reduction of 4-nitrophenol with high reaction rate. Moreover, the fibrous Ag/cotton composites were capable to form a desirable catalytic mat for catalyzing and simultaneous product separation. Reactants passing through the mat could be catalytically transformed to product, which is of great significance for water treatment. Such catalyst (FAC) was thus expected to have the potential as a highly efficient, cost-effective and eco-friendly catalyst for industrial applications. More importantly, this newly developed synthetic methodology could serve as a general tool to design and synthesize other metal/biomass composites catalysts for a wider range of catalytic applications.

Problem Severity Profiles of Substance Abusing Women in Therapeutic Treatment Facilities

ERIC Educational Resources Information Center

Isralowitz, Richard; Reznik, Alexander

2009-01-01

This article aims to examine specific substance use profiles among former Soviet Union (FSU) immigrant and native-born women in Israeli therapeutic treatment facilities. Individuals were sampled at drug treatment facilities and assessed using the Addiction Severity Index. ASI scores suggest differences between the two groups. Among the findings…

An Electronic Pressure Profile Display system for aeronautic test facilities

NASA Technical Reports Server (NTRS)

Woike, Mark R.

1990-01-01

The NASA Lewis Research Center has installed an Electronic Pressure Profile Display system. This system provides for the real-time display of pressure readings on high resolution graphics monitors. The Electronic Pressure Profile Display system will replace manometer banks currently used in aeronautic test facilities. The Electronic Pressure Profile Display system consists of an industrial type Digital Pressure Transmitter (DPI) unit which interfaces with a host computer. The host computer collects the pressure data from the DPI unit, converts it into engineering units, and displays the readings on a high resolution graphics monitor in bar graph format. Software was developed to accomplish the above tasks and also draw facility diagrams as background information on the displays. Data transfer between host computer and DPT unit is done with serial communications. Up to 64 channels are displayed with one second update time. This paper describes the system configuration, its features, and its advantages over existing systems.

An electronic pressure profile display system for aeronautic test facilities

NASA Technical Reports Server (NTRS)

Woike, Mark R.

1990-01-01

The NASA Lewis Research Center has installed an Electronic Pressure Profile Display system. This system provides for the real-time display of pressure readings on high resolution graphics monitors. The Electronic Pressure Profile Display system will replace manometer banks currently used in aeronautic test facilities. The Electronic Pressure Profile Display system consists of an industrial type Digital Pressure Transmitter (DPT) unit which interfaces with a host computer. The host computer collects the pressure data from the DPT unit, converts it into engineering units, and displays the readings on a high resolution graphics monitor in bar graph format. Software was developed to accomplish the above tasks and also draw facility diagrams as background information on the displays. Data transfer between host computer and DPT unit is done with serial communications. Up to 64 channels are displayed with one second update time. This paper describes the system configuration, its features, and its advantages over existing systems.

Neutron Depth Profiling: Overview and Description of NIST Facilities

PubMed Central

Downing, R. G.; Lamaze, G. P.; Langland, J. K.; Hwang, S. T.

1993-01-01

The Cold Neutron Depth Profiling (CNDP) instrument at the NIST Cold Neutron Research Facility (CNRF) is now operational. The neutron beam originates from a 16 L D2O ice cold source and passes through a filter of 135 mm of single crystal sapphire. The neutron energy spectrum may be described by a 65 K Maxwellian distribution. The sample chamber configuration allows for remote controlled scanning of 150 × 150 mm sample areas including the varying of both sample and detector angle. The improved sensitivity over the current thermal depth profiling instrument has permitted the first nondestructive measurements of 17O profiles. This paper describes the CNDP instrument, illustrates the neutron depth profiling (NDP) technique with examples, and gives a separate bibliography of NDP publications. PMID:28053461

Replacing Ag(TS)SCH(2)-R with Ag(TS)O(2)C-R in EGaIn-based tunneling junctions does not significantly change rates of charge transport.

PubMed

Liao, Kung-Ching; Yoon, Hyo Jae; Bowers, Carleen M; Simeone, Felice C; Whitesides, George M

2014-04-07

This paper compares rates of charge transport by tunneling across junctions with the structures Ag(TS) X(CH2 )2n CH3  //Ga2 O3  /EGaIn (n=1-8 and X= SCH2  and O2 C); here Ag(TS) is template-stripped silver, and EGaIn is the eutectic alloy of gallium and indium. Its objective was to compare the tunneling decay coefficient (β, Å(-1) ) and the injection current (J0 , A cm(-2) ) of the junctions comprising SAMs of n-alkanethiolates and n-alkanoates. Replacing Ag(TS) SCH2 -R with Ag(TS) O2 C-R (R=alkyl chains) had no significant influence on J0 (ca. 3×10(3)  A cm(-2) ) or β (0.75-0.79 Å(-1) )-an indication that such changes (both structural and electronic) in the Ag(TS) XR interface do not influence the rate of charge transport. A comparison of junctions comprising oligo(phenylene)carboxylates and n-alkanoates showed, as expected, that β for aliphatic (0.79 Å(-1) ) and aromatic (0.60 Å(-1) ) SAMs differed significantly. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ChIP-chip.

PubMed

Kim, Tae Hoon; Dekker, Job

2018-05-01

ChIP-chip can be used to analyze protein-DNA interactions in a region-wide and genome-wide manner. DNA microarrays contain PCR products or oligonucleotide probes that are designed to represent genomic sequences. Identification of genomic sites that interact with a specific protein is based on competitive hybridization of the ChIP-enriched DNA and the input DNA to DNA microarrays. The ChIP-chip protocol can be divided into two main sections: Amplification of ChIP DNA and hybridization of ChIP DNA to arrays. A large amount of DNA is required to hybridize to DNA arrays, and hybridization to a set of multiple commercial arrays that represent the entire human genome requires two rounds of PCR amplifications. The relative hybridization intensity of ChIP DNA and that of the input DNA is used to determine whether the probe sequence is a potential site of protein-DNA interaction. Resolution of actual genomic sites bound by the protein is dependent on the size of the chromatin and on the genomic distance between the probes on the array. As with expression profiling using gene chips, ChIP-chip experiments require multiple replicates for reliable statistical measure of protein-DNA interactions. © 2018 Cold Spring Harbor Laboratory Press.

Comparison of the GOSAT TANSO-FTS TIR CH volume mixing ratio vertical profiles with those measured by ACE-FTS, ESA MIPAS, IMK-IAA MIPAS, and 16 NDACC stations

NASA Astrophysics Data System (ADS)

Olsen, Kevin S.; Strong, Kimberly; Walker, Kaley A.; Boone, Chris D.; Raspollini, Piera; Plieninger, Johannes; Bader, Whitney; Conway, Stephanie; Grutter, Michel; Hannigan, James W.; Hase, Frank; Jones, Nicholas; de Mazière, Martine; Notholt, Justus; Schneider, Matthias; Smale, Dan; Sussmann, Ralf; Saitoh, Naoko

2017-10-01

The primary instrument on the Greenhouse gases Observing SATellite (GOSAT) is the Thermal And Near infrared Sensor for carbon Observations (TANSO) Fourier transform spectrometer (FTS). TANSO-FTS uses three short-wave infrared (SWIR) bands to retrieve total columns of CO2 and CH4 along its optical line of sight and one thermal infrared (TIR) channel to retrieve vertical profiles of CO2 and CH4 volume mixing ratios (VMRs) in the troposphere. We examine version 1 of the TANSO-FTS TIR CH4 product by comparing co-located CH4 VMR vertical profiles from two other remote-sensing FTS systems: the Canadian Space Agency's Atmospheric Chemistry Experiment FTS (ACE-FTS) on SCISAT (version 3.5) and the European Space Agency's Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat (ESA ML2PP version 6 and IMK-IAA reduced-resolution version V5R_CH4_224/225), as well as 16 ground stations with the Network for the Detection of Atmospheric Composition Change (NDACC). This work follows an initial inter-comparison study over the Arctic, which incorporated a ground-based FTS at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Canada, and focuses on tropospheric and lower-stratospheric measurements made at middle and tropical latitudes between 2009 and 2013 (mid-2012 for MIPAS). For comparison, vertical profiles from all instruments are interpolated onto a common pressure grid, and smoothing is applied to ACE-FTS, MIPAS, and NDACC vertical profiles. Smoothing is needed to account for differences between the vertical resolution of each instrument and differences in the dependence on a priori profiles. The smoothing operators use the TANSO-FTS a priori and averaging kernels in all cases. We present zonally averaged mean CH4 differences between each instrument and TANSO-FTS with and without smoothing, and we examine their information content, their sensitive altitude range, their correlation, their a priori dependence, and the variability within

Spatial distribution of CH3 and CH2 radicals in a methane rf discharge

NASA Astrophysics Data System (ADS)

Sugai, H.; Kojima, H.; Ishida, A.; Toyoda, H.

1990-06-01

Spatial distributions of neutral radicals CH3 and CH2 in a capacitively coupled rf glow discharge of methane were measured by threshold ionization mass spectrometry. A strong asymmetry of the density profile was found for the CH2 radical in the high-pressure (˜100 mTorr) discharge. In addition, comprehensive measurements of electron energy distribution, ionic composition, and radical sticking coefficient were made to use as inputs to theoretical modeling of radicals in the methane plasma. The model predictions agree substantially with the measured radical distributions.

Hospitality and Facility Care Services. Ohio's Competency Analysis Profile.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. Vocational Instructional Materials Lab.

Developed through a modified DACUM (Developing a Curriculum) process involving business, industry, labor, and community agency representatives in Ohio, this document is a comprehensive and verified employer competency profile for hospitality and facility care occupations. The list contains units (with and without subunits), competencies, and…

Facile synthesis of hierarchical Ag3PO4/TiO2 nanofiber heterostructures with highly enhanced visible light photocatalytic properties

NASA Astrophysics Data System (ADS)

Xie, Jinlei; Yang, Yefeng; He, Haiping; Cheng, Ding; Mao, Minmin; Jiang, Qinxu; Song, Lixin; Xiong, Jie

2015-11-01

Heterostructured semiconductor nanostructures have provoked great interest in the areas of energy, environment and catalysis. Herein, we report a novel hierarchical Ag3PO4/TiO2 heterostructure consisting of nearly spherical Ag3PO4 particles firmly coupled on the surface of TiO2 nanofibers (NFs). The construction of Ag3PO4/TiO2 heterostructure with tailored morphologies, compositions and optical properties was simply achieved via a facile and green synthetic strategy involving the electrospinning and solution-based processes. Owing to the synergetic effects of the components, the resulting hybrid heterostructures exhibited much improved visible light photocatalytic performance, which could degrade the RhB dye completely in 7.5 min. In addition, the coupling of Ag3PO4 particles with UV-light-sensitive TiO2 NFs enabled full utilization of solar energy and less consumption of noble metals, significantly appealing for their practical use in new energy sources and environmental issues. The developed synthetic strategy was considered to be applicable for the rational design and construction of other heterostructured catalysts.

Experimental and Computational Study fo CH, CH*, and OH* in an Axisymmetric Laminar Diffusion Flame

NASA Technical Reports Server (NTRS)

Walsh, K. T.

1998-01-01

In this study, we extend the results of previous combined numerical and experimental investigations of an axisymmetric laminar diffusion flame in which difference Raman spectroscopy, laser-induced fluorescence (LIF), and a multidimensional flame model were used to generate profiles of the temperature and major and minor species. A procedure is outlined by which the number densities of ground-state CH (X(sup 2)II) excited-state CH (A(sup 2)Delta, denoted CH*), and excited-state OH (A(sup 2)Sigma, denoted OH*) are measured and modeled. CH* and OH* number densities are deconvoluted from line-of-sight flame-emission measurements. Ground-state CH is measured using linear LIF. The computations are done with GRI Mech 2.11 as well as an alternate hydrocarbon mechanism. In both cases, additional reactions for the production and consumption of CH* and OH* are added from recent kinetic studies. Collisional quenching and spontaneous emission are responsible for the de-excitation of the excited-state radicals. As with our previous investigations, GRI Mech 2.11 continues to produce very good agreement with the overall flame length observed in the experiments, while significantly under predicting the flame lift-off height. The alternate kinetic scheme is much more accurate in predicting lift-off height but overpredicts the over-all flame length. Ground-state CH profiles predicted with GRI Mech 2.11 are in excellent agreement with the corresponding measurements, regarding both spatial distribution and absolute concentration (measured at 4 ppm) of the CH radical. Calculations of the excited-state species show reasonable agreement with the measurements as far as spatial distribution and overall characteristics are concerned. For OH*, the measured peak mole fraction, 1.3 x 10(exp -8), compared well with computed peaks, while the measured peak level for CH*, 2 x 10(exp -9), was severely underpredicted by both kinetic schemes, indicating that the formation and destruction kinetics

Reduction of Ag{sup I}, Au{sup III}, Cu{sup II}, and Hg{sup II} by Fe{sup II}/Fe{sup III} hydroxysulfate green rust.

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

O'Loughlin, E. J.; Kelly, S. D.; Kemner, K. M.

Green rusts are mixed Fe{sup II}/Fe{sup III} hydroxides that are found in many suboxic environments where they are believed to play a central role in the biogeochemical cycling of iron. X-ray absorption fine structure analysis of hydroxysulfate green rust suspensions spiked with aqueous solutions of AgCH{sub 3}COO, AuCl{sub n}(OH){sub 4-n}, CuCl{sub 2}, or HgCl{sub 2} showed that Ag{sup I}, Au{sup III}, Cu{sup II}, and Hg{sup II} were readily reduced to Ag{sup 0}, Au{sup 0}, Cu{sup 0}, and Hg{sup 0}. Imaging of the resulting solids from the Ag{sup I}-, Au{sup III}-, and Cu{sup II}-amended green rust suspensions by transmission electron microscopymore » indicated the formation of submicron-sized particles of Ag{sup 0}, Au{sup 0}, and Cu{sup 0}. The facile reduction of Ag{sup I}, Au{sup III}, Cu{sup II}, and Hg{sup II} to Ag{sup 0}, Au{sup 0}, Cu{sup 0}, and Hg{sup 0}, respectively, by green rust suggests that the presence of green rusts in suboxic soils and sediments can have a significant impact on the biogeochemistry of silver, gold, copper, and mercury, particularly with respect to their mobility.« less

Enhanced Visible Light Photocatalytic Degradation of Organic Pollutants over Flower-Like Bi₂O₂CO₃ Dotted with Ag@AgBr.

PubMed

Lin, Shuanglong; Wang, Miao; Liu, Li; Liang, Yinghua; Cui, Wenquan; Zhang, Zisheng; Yun, Nan

2016-10-31

A facile and feasible oil-in-water self-assembly approach was developed to synthesize flower-like Ag@AgBr/Bi₂O₂CO₃ micro-composites. The photocatalytic activities of the samples were evaluated through methylene blue degradation under visible light irradiation. Compared to Bi₂O₂CO₃, flower-like Ag@AgBr/Bi₂O₂CO₃ micro-composites show enhanced photocatalytic activities. In addition, results indicate that both the physicochemical properties and associated photocatalytic activities of Ag@AgBr/Bi₂O₂CO₃ composites are shown to be dependent on the loading quantity of Ag@AgBr. The highest photocatalytic performance was achieved at 7 wt % Ag@AgBr, degrading 95.18% methylene blue (MB) after 20 min of irradiation, which is over 1.52 and 3.56 times more efficient than that of pure Ag@AgBr and pure Bi₂O₂CO₃, respectively. Bisphenol A (BPA) was also degraded to further demonstrate the degradation ability of Ag@AgBr/Bi₂O₂CO₃. A photocatalytic mechanism for the degradation of organic compounds over Ag@AgBr/Bi₂O₂CO₃ was proposed. Results from this study illustrate an entirely new approach to fabricate semiconductor composites containing Ag@AgX/bismuth (X = a halogen).

Two-wavelength single laser CH and CH(4) imaging in a lifted turbulent diffusion flame.

PubMed

Namazian, M; Schmitt, R L; Long, M B

1988-09-01

A new technique has been developed which allows simultaneous 2-D mapping of CH and CH 4 in a turbulent methane flame. A flashlamp-pumped dye laser using two back mirrors produces output at 431.5 and 444 nm simultaneously. The 431.5-nm line is used to excite the (0, 0) band of the A(2)Delta-X(2)Pi system of CH, and the fluorescence of the (0, 1) transition is observed at 489 nm. Coincidentally, the spontaneous Raman scattering from CH(4) also occurs near 489 nm for a 431.5-nm excitation. To separate the CH(4) and CH contributions, the 444-nm line is used to produce a spontaneous Raman signal from CH(4) that is spectrally separated from the CH fluorescence. Subtraction of the signals generated by the 431.5- and 444-nm wavelength beams yields separate measurements of CH(4) and CH. Raman-scattered light records the instantaneous distribution of the fuel, and simultaneously the CH fluorescence indicates the location of the flame zone. The resulting composite images provide important insight on the interrelationship between fuel-air mixing and subsequent combustion.M. Namazian is with Altex Technologies Corporation, 109 Via De Tesoros, Los Gatos, California 95030; R. L. Schmitt is with Sandia National Laboratories, Combustion Research Facility, Livermore, California 94550; and M. B. Long is with Yale University, Department of Mechanical Engineering, New Haven, Connecticut 06520.

CH_{4} production in the deep soil as a source of stem CH_{4} emission in Fagus sylvatica}

NASA Astrophysics Data System (ADS)

Maier, Martin; Machacova, Katerina; Urban, Otmar; Lang, Friederike

2017-04-01

Predicting greenhouse gas (GHG) fluxes on a global scale requires understanding fluxes on the local scale. Understanding GHG processes in soil-plant-atmosphere systems is essential to understand and mitigate GHG fluxes on the local scale. Forests are known to act as carbon sink. Yet, trees at waterlogged sites are known to emit large amounts of CH4, what can offset the positive GHG balance due the CO2 that is sequestered as wood. Generally, upland trees like European beech (Fagus sylvatica L.) are assumed not to emit CH4, and the upland forest soils are regarded as CH4 sinks. Soil-atmosphere fluxes and stem-atmosphere fluxes of CH4 were studied together with soil gas profiles at two upland beech forest sites in Germany and Czech Republic. Soil was a net CH4 sink at both sites. While most trees showed no or low emissions, one beech tree had exorbitant CH4 emissions that were higher than the CH4 sink capacity of the soil. A soil survey showed strong redoximorphic color patterns in the soil adjacent to this tree. Although the soil around the tree was taking up CH4, the soil gas profiles around this tree showed CH4 production at a soil depth >0.3 m. We interpret the coincidence of the production of CH4 in the deep soil below the beech with the large stem emissions as strong hint that there is a transport link between the soil and stem. We think that the root system represents a preferential transport system for CH4 despite the fact that beech roots usually do not have a special gas transport tissue. The observed CH4 stem emissions represent an important CH4 flux in this ecosystem, and, thus, should be considered in future research. Acknowledgement This research was supported by the Czech Academy of Sciences and the German Academic Exchange Service within the project "Methane (CH4) and nitrous oxide (N2O) emissions from Fagus sylvatica trees" (DAAD-15-03), the Czech Science Foundation (17-18112Y), National Programme for Sustainability I (LO1415) and project DFG (MA 5826

The Drivers of the CH4 Seasonal Cycle in the Arctic and What Long-Term Observations of CH4 Imply About Trends in Arctic CH4 Fluxes

NASA Astrophysics Data System (ADS)

Sweeney, C.; Karion, A.; Bruhwiler, L.; Miller, J. B.; Wofsy, S. C.; Miller, C. E.; Chang, R. Y.; Dlugokencky, E. J.; Daube, B.; Pittman, J. V.; Dinardo, S. J.

2012-12-01

The large seasonal change in the atmospheric column for CH4 in the Arctic is driven by two dominant processes: transport of CH4 from low latitudes and surface emissions throughout the Arctic region. The NOAA ESRL Carbon Cycle Group Aircraft Program along with the NASA funded Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) have initiated an effort to better understand the factors controlling the seasonal changes in the mole fraction of CH4 in the Arctic with a multi-scale aircraft observing network in Alaska. The backbone of this network is multi-species flask sampling from 500 to 8000 masl that has been conducted every two weeks for the last 10 years over Poker Flat, AK. In addition regular profiles at the interior Alaska site at Poker Flat, NOAA has teamed up with the United States Coast Guard to make profiling flights with continuous observations of CO2, CO, CH4 and Ozone between Kodiak and Barrow every 2 weeks. More recently, CARVE has significantly added to this observational network with targeted flights focused on exploring the variability of CO2, CH4 and CO in the boundary layer both in the interior and the North Slope regions of Alaska. Taken together with the profiling of HIAPER Pole-to-Pole Observations (HIPPO), ground sites at Barrow and a new CARVE interior Alaska surface site just north of Fairbanks, AK, we now have the ability to investigate the full evolution of the seasonal cycle in the Arctic using both the multi-scale sampling offered by the different aircraft platforms as well as the multi-species sampling offered by in-situ and flask sampling. The flasks also provide a valuable tie-point between different platforms so that spatial and temporal gradients can be properly interpreted. In the context of the seasonal cycle observed by the aircraft platforms we will look at long term ground observations over the last 20 years to assess changes in Arctic CH4 emissions which have occurred as a result of 0.6C/decade changes in mean surface

iTAR: a web server for identifying target genes of transcription factors using ChIP-seq or ChIP-chip data.

PubMed

Yang, Chia-Chun; Andrews, Erik H; Chen, Min-Hsuan; Wang, Wan-Yu; Chen, Jeremy J W; Gerstein, Mark; Liu, Chun-Chi; Cheng, Chao

2016-08-12

Chromatin immunoprecipitation followed by massively parallel DNA sequencing (ChIP-seq) or microarray hybridization (ChIP-chip) has been widely used to determine the genomic occupation of transcription factors (TFs). We have previously developed a probabilistic method, called TIP (Target Identification from Profiles), to identify TF target genes using ChIP-seq/ChIP-chip data. To achieve high specificity, TIP applies a conservative method to estimate significance of target genes, with the trade-off being a relatively low sensitivity of target gene identification compared to other methods. Additionally, TIP's output does not render binding-peak locations or intensity, information highly useful for visualization and general experimental biological use, while the variability of ChIP-seq/ChIP-chip file formats has made input into TIP more difficult than desired. To improve upon these facets, here we present are fined TIP with key extensions. First, it implements a Gaussian mixture model for p-value estimation, increasing target gene identification sensitivity and more accurately capturing the shape of TF binding profile distributions. Second, it enables the incorporation of TF binding-peak data by identifying their locations in significant target gene promoter regions and quantifies their strengths. Finally, for full ease of implementation we have incorporated it into a web server ( http://syslab3.nchu.edu.tw/iTAR/ ) that enables flexibility of input file format, can be used across multiple species and genome assembly versions, and is freely available for public use. The web server additionally performs GO enrichment analysis for the identified target genes to reveal the potential function of the corresponding TF. The iTAR web server provides a user-friendly interface and supports target gene identification in seven species, ranging from yeast to human. To facilitate investigating the quality of ChIP-seq/ChIP-chip data, the web server generates the chart of the

Subsoil methanogenesis as source of stem CH4 emission in upland forest trees: preferential CH4 transport via the root system?

NASA Astrophysics Data System (ADS)

Maier, M.; Machacova, K.; Urban, O.; Friederike, L.

2016-12-01

Quantifying and understanding green house gas fluxes in natural soil-plant-atmosphere systems are crucial to predicting global climate change. Wetland species or trees at waterlogged sites are known to emit large amounts of CH4. Yet upland forest soils are regarded as CH4 sinks and tree species like upland European beech (Fagus sylvatica, L.) are assumed not to emit CH4. We studied the soil-atmosphere and stem-atmosphere fluxes of CH4, and soil gas profiles at two upland beech forest sites in Central Europe. Soil was a net CH4 sink at both. Unusually there was one beech tree with substantial CH4 emissions that were higher than the CH4 sink of the soil. The soil gas profile at this tree indicated CH4 production at a soil depth >0.3 m, despite the net uptake of CH4 observed at the soil surface adjacent to the tree. Field soil assessment showed strong redoximorphic color patterns in the adjacent soil. We think that there is a transport link between the soil and stem via the root system representing a preferential transport mechanism for CH4 despite the fact that beech roots usually do not bear aerenchyma. The gas transport process , either via dissolved CH4 in the xylem water or in the root gas phase, is not yet clear. The observed CH4 stem emissions represent an important CH4flux in this ecosystem, und thus should be considered in future research. AcknowledgementThis research was financially supported by the Czech Academy of Sciences and the German Academic Exchange Service within the project "Methane (CH4) and nitrous oxide (N2O) emissions from Fagus sylvatica trees" (DAAD-15-03), National Programme for Sustainability I (LO1415) and project DFG (MA 5826/2-1). We would like to thank Marek Jakubik, Katerina Svobodova, Sinikka Paulus, Ellen Halaburt and Sally Haddad for technical support.

Facile Synthesis of Efficient Antibacterial Agent as CoFe₂O₄/Ag Composite Material Against Both Gram-Negative Escherichia coli and Gram-Positive Bacillus subtilis Bacteria.

PubMed

Gankhuyag, Sukhbayar; Lee, Kyoung; Bae, Dong Sik

2018-09-01

We have suggested that a facile synthesis of CoFe2O4/Ag composite material as an antibacterial agent for substitution of a chlorination agent for microbial infected wastewater treatment. The CoFe2O4/Ag was synthesized by an impregnation method in assistance with trisodium citrate as a reducing agent. The as-prepared uncalcined CoFe2O4 (CFG), calcined CoFe2O4 (CFG600), and calcined CoFe2O4/Ag (CFG600/Ag) composites were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray (EDX) techniques. Antibacterial activities were also determined in liquid culture by measuring the minimum inhibitory concentrations (MIC) against Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis (B. subtilis) bacteria in vitro. Results showed that CFG600/Ag composites had an excellent antibacterial activity in comparison with CFG and CFG600 composites. The CFG600/Ag composites have completely inhibited the growth of both E. coli and B. subtilis bacteria from concentrations of more than 0.25 mg/ml. Furthermore, the FE-SEM study demonstrated the physical damage of bacteria when treated with CFG600/Ag composite material at a concentration of 0.10 mg/ml.

Analysis of Protein-DNA Interaction by Chromatin Immunoprecipitation and DNA Tiling Microarray (ChIP-on-chip).

PubMed

Gao, Hui; Zhao, Chunyan

2018-01-01

Chromatin immunoprecipitation (ChIP) has become the most effective and widely used tool to study the interactions between specific proteins or modified forms of proteins and a genomic DNA region. Combined with genome-wide profiling technologies, such as microarray hybridization (ChIP-on-chip) or massively parallel sequencing (ChIP-seq), ChIP could provide a genome-wide mapping of in vivo protein-DNA interactions in various organisms. Here, we describe a protocol of ChIP-on-chip that uses tiling microarray to obtain a genome-wide profiling of ChIPed DNA.

A research on shape-controllable synthesis of Ag3PO4/AgBr and its degradation of ciprofloxacin.

PubMed

Chen, Jingran; Yang, Xingyu; Zhu, Chenyu; Xie, Xin; Lin, Cuiping; Zhao, Yalei; Yan, Qishe

2018-03-01

Antibiotic ciprofloxacin is one of the commonly used broad spectrum fluoroquinolone human and veterinary drugs. Because of the overuse of human beings, the presence of ciprofloxacin has been detected in a variety of environmental matrices. To solve this problem, a facile, environmentally-friendly Ag 3 PO 4 /AgBr composite photocatalyst was synthesized by a simple precipitation method at room temperature in the presence of cetyltrimethyl ammonium bromide (CTAB). CTAB was served as surfactant and the source of bromide ions. The as-prepared Ag 3 PO 4 /AgBr microspheres were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). The results revealed that the Ag 3 PO 4 /AgBr sample (synthesized with CTAB, 0.8 g) exhibited the highest photocatalytic activity to the photodegradation rate of 96.36%. Moreover, mechanism detection experiment indicated that h + was the major active species in the degradation process. So the enhanced photocatalytic activity of Ag 3 PO 4 /AgBr composites is attributed to its excellent separation of photogenerated electron-hole pairs through Ag 3 PO 4 /AgBr heterojunction. Also, Ag 3 PO 4 /AgBr heterojunction has a lower band gap compared to pure Ag 3 PO 4 and pure AgBr, so higher efficiency of light harvesting is equipped.

Substrate-Mediated C-C and C-H Coupling after Dehalogenation.

PubMed

Kong, Huihui; Yang, Sha; Gao, Hongying; Timmer, Alexander; Hill, Jonathan P; Díaz Arado, Oscar; Mönig, Harry; Huang, Xinyan; Tang, Qin; Ji, Qingmin; Liu, Wei; Fuchs, Harald

2017-03-15

Intermolecular C-C coupling after cleavage of C-X (mostly, X = Br or I) bonds has been extensively studied for facilitating the synthesis of polymeric nanostructures. However, the accidental appearance of C-H coupling at the terminal carbon atoms would limit the successive extension of covalent polymers. To our knowledge, the selective C-H coupling after dehalogenation has not so far been reported, which may illuminate another interesting field of chemical synthesis on surfaces besides in situ fabrication of polymers, i.e., synthesis of novel organic molecules. By combining STM imaging, XPS analysis, and DFT calculations, we have achieved predominant C-C coupling on Au(111) and more interestingly selective C-H coupling on Ag(111), which in turn leads to selective synthesis of polymeric chains or new organic molecules.

Introducing ionic and/or hydrogen bonds into the SAM//Ga2O3 top-interface of Ag(TS)/S(CH2)nT//Ga2O3/EGaIn junctions.

PubMed

Bowers, Carleen M; Liao, Kung-Ching; Yoon, Hyo Jae; Rappoport, Dmitrij; Baghbanzadeh, Mostafa; Simeone, Felice C; Whitesides, George M

2014-06-11

Junctions with the structure Ag(TS)/S(CH2)nT//Ga2O3/EGaIn (where S(CH2)nT is a self-assembled monolayer, SAM, of n-alkanethiolate bearing a terminal functional group T) make it possible to examine the response of rates of charge transport by tunneling to changes in the strength of the interaction between T and Ga2O3. Introducing a series of Lewis acidic/basic functional groups (T = -OH, -SH, -CO2H, -CONH2, and -PO3H) at the terminus of the SAM gave values for the tunneling current density, J(V) in A/cm(2), that were indistinguishable (i.e., differed by less than a factor of 3) from the values observed with n-alkanethiolates of equivalent length. The insensitivity of the rate of tunneling to changes in the terminal functional group implies that replacing weak van der Waals contact interactions with stronger hydrogen- or ionic bonds at the T//Ga2O3 interface does not change the shape (i.e., the height or width) of the tunneling barrier enough to affect rates of charge transport. A comparison of the injection current, J0, for T = -CO2H, and T = -CH2CH3--two groups having similar extended lengths (in Å, or in numbers of non-hydrogen atoms)--suggests that both groups make indistinguishable contributions to the height of the tunneling barrier.

Synthesis of β-AgVO3 nanowires decorated with Ag2CrO4, with improved visible light photocatalytic performance

NASA Astrophysics Data System (ADS)

Ouyang, Qi; Li, Zhonghua; Liu, Jiawen

2018-05-01

Silver chromate‑silver vanadate (Ag2CrO4/β-AgVO3) heterojunction composites are synthesized through a facile precipitation process. The Ag2CrO4/β-AgVO3 hybrids obtained exhibit better photocatalytic activity in degradation of RhB than both pure Ag2CrO4 and β-AgVO3 under visible light irradiation. The 20 wt% Ag2CrO4/β-AgVO3 heterojunction possesses the best photocatalytic ability for degrading RhB: 24.4 times that of pristine β-AgVO3 nanowires and 3.2 times that of individual Ag2CrO4 particles. The phase of the nanocomposites was analyzed using x-ray diffraction as well as x-ray photoelectron spectroscopy. Their morphology was observed via scanning electron microscopy and transmission electron microscopy. The improvement in photocatalytic performance is chiefly ascribed to the synergies between Ag2CrO4/β-AgVO3 heterostructure, which can enhance the light absorbance ability and also accelerate the separation and transfer of photoinduced electrons and holes under visible light irradiation; this is also confirmed by UV–vis diffuse reflection spectrometry and fluorescence emission spectra.

Photolysis of CH{sub 3}CHO at 248 nm: Evidence of triple fragmentation from primary quantum yield of CH{sub 3} and HCO radicals and H atoms

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

Morajkar, Pranay; Schoemaecker, Coralie; Fittschen, Christa, E-mail: christa.fittschen@univ-lille1.fr

2014-06-07

Radical quantum yields have been measured following the 248 nm photolysis of acetaldehyde, CH{sub 3}CHO. HCO radical and H atom yields have been quantified by time resolved continuous wave Cavity Ring Down Spectroscopy in the near infrared following their conversion to HO{sub 2} radicals by reaction with O{sub 2}. The CH{sub 3} radical yield has been determined using the same technique following their conversion into CH{sub 3}O{sub 2}. Absolute yields have been deduced for HCO radicals and H atoms through fitting of time resolved HO{sub 2} profiles, obtained under various O{sub 2} concentrations, to a complex model, while the CH{submore » 3} yield has been determined relative to the CH{sub 3} yield from 248 nm photolysis of CH{sub 3}I. Time resolved HO{sub 2} profiles under very low O{sub 2} concentrations suggest that another unknown HO{sub 2} forming reaction path exists in this reaction system besides the conversion of HCO radicals and H atoms by reaction with O{sub 2}. HO{sub 2} profiles can be well reproduced under a large range of experimental conditions with the following quantum yields: CH{sub 3}CHO + hν{sub 248nm} → CH{sub 3}CHO{sup *}, CH{sub 3}CHO{sup *} → CH{sub 3} + HCO ϕ{sub 1a} = 0.125 ± 0.03, CH{sub 3}CHO{sup *} → CH{sub 3} + H + CO ϕ{sub 1e} = 0.205 ± 0.04, CH{sub 3}CHO{sup *}→{sup o{sub 2}}CH{sub 3}CO + HO{sub 2} ϕ{sub 1f} = 0.07 ± 0.01. The CH{sub 3}O{sub 2} quantum yield has been determined in separate experiments as ϕ{sub CH{sub 3}} = 0.33 ± 0.03 and is in excellent agreement with the CH{sub 3} yields derived from the HO{sub 2} measurements considering that the triple fragmentation (R1e) is an important reaction path in the 248 nm photolysis of CH{sub 3}CHO. From arithmetic considerations taking into account the HO{sub 2} and CH{sub 3} measurements we deduce a remaining quantum yield for the molecular pathway: CH{sub 3}CHO{sup *} → CH{sub 4} + CO ϕ{sub 1b} = 0.6. All experiments

Facile fabrication of Ag3VO4/attapulgite composites for highly efficient visible light-driven photodegradation towards organic dyes and tetracycline hydrochloride

NASA Astrophysics Data System (ADS)

Luo, Yuting; Luo, Jie; Duan, Guorong; Liu, Xiaoheng

2017-12-01

An efficient one-dimensional attapulgite (ATP)-based photocatalyst, Ag3VO4/ATP nanocomposite, was fabricated by a facile deposition precipitation method with well-dispersed Ag3VO4 nanoparticles anchored on the surface of natural ATP fibers. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and UV-visible diffused reflectance spectroscopy (UV-vis DRS) were employed to investigate the morphologies, structure, and optical property of the prepared photocatalysts. The photocatalytic experiments indicated that the Ag3VO4/ATP nanocomposites exhibited enhanced visible light-driven photocatalytic activity towards the degradation of rhodamine B (RhB), methyl orange (MO), and tetracycline hydrochloride (TCH), of which the 20 wt% Ag3VO4/ATP sample showed superb photocatalytic performance. As demonstrated by N2 adsorption-desorption, photocurrent measurements, electrochemical impedance spectroscopy (EIS), and photoluminescence (PL) spectra analyses, the improved photocatalytic activity arose from the enlarged surface area, the facilitated charge transfer, and the suppressed recombination of photogenerated charge carriers in Ag3VO4/ATP system. Furthermore, radical scavengers trapping experiments and recycling tests were also conducted. This work gives a new insight into fabrication of highly efficient, stable, and cost-effective visible light-driven photocatalyst for practical application in wastewater treatment and environmental remediation.

Multiplexed ChIP-Seq Using Direct Nucleosome Barcoding: A Tool for High-Throughput Chromatin Analysis.

PubMed

Chabbert, Christophe D; Adjalley, Sophie H; Steinmetz, Lars M; Pelechano, Vicent

2018-01-01

Chromatin immunoprecipitation followed by sequencing (ChIP-Seq) or microarray hybridization (ChIP-on-chip) are standard methods for the study of transcription factor binding sites and histone chemical modifications. However, these approaches only allow profiling of a single factor or protein modification at a time.In this chapter, we present Bar-ChIP, a higher throughput version of ChIP-Seq that relies on the direct ligation of molecular barcodes to chromatin fragments. Bar-ChIP enables the concurrent profiling of multiple DNA-protein interactions and is therefore amenable to experimental scale-up, without the need for any robotic instrumentation.

Preparation of AgInS2 quantum dot/In2S3 co-sensitized photoelectrodes by a facile aqueous-phase synthesis route and their photovoltaic performance

NASA Astrophysics Data System (ADS)

Wang, Yuanqiang; Zhang, Qinghong; Li, Yaogang; Wang, Hongzhi

2015-03-01

In an aqueous-phase system, AgInS2 quantum dot (QD) sensitized TiO2 photoanodes were prepared in situ by the reaction of β-In2S3 nanocrystals and as-prepared TiO2/Ag2S-QD electrodes, followed by a covering process with a ZnS passivation layer. A facile successive ionic layer adsorption and reaction (SILAR) method was adopted to obtain TiO2/Ag2S-QD electrodes. β-In2S3 nanocrystals synthesized by the chemical bath deposition (CBD) process serve as the reactant of AgInS2 as well as a buffer layer between the interfaces of TiO2 and AgInS2-QDs. A polysulfide electrolyte and a Pt-coated FTO glass count electrode were used to test the photovoltaic performance of the constructed devices. The characteristics of the sensitized photoelectrodes were studied in more detail by electron microscopy, X-ray techniques, and optical and photoelectric performance measurements. AgInS2 is the main photo-sensitizer for TiO2/AgInS2-QD/In2S3 electrodes and excess In2S3 appears on the surface of the electrodes. Based on the optimal Ag2S SILAR cycle, the best photovoltaic performance of the prepared TiO2/AgInS2-QD/In2S3 electrode with the short-circuit photocurrent density (Jsc) of 7.87 mA cm-2 and power conversion efficiency (η) of 0.70% under full one-sun illumination was achieved.In an aqueous-phase system, AgInS2 quantum dot (QD) sensitized TiO2 photoanodes were prepared in situ by the reaction of β-In2S3 nanocrystals and as-prepared TiO2/Ag2S-QD electrodes, followed by a covering process with a ZnS passivation layer. A facile successive ionic layer adsorption and reaction (SILAR) method was adopted to obtain TiO2/Ag2S-QD electrodes. β-In2S3 nanocrystals synthesized by the chemical bath deposition (CBD) process serve as the reactant of AgInS2 as well as a buffer layer between the interfaces of TiO2 and AgInS2-QDs. A polysulfide electrolyte and a Pt-coated FTO glass count electrode were used to test the photovoltaic performance of the constructed devices. The characteristics of the

Accelerator Facilities for Radiation Research

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.

1999-01-01

HSRP Goals in Accelerator Use and Development are: 1.Need for ground-based heavy ion and proton facility to understand space radiation effects discussed most recently by NAS/NRC Report (1996). 2. Strategic Program Goals in facility usage and development: -(1) operation of AGS for approximately 600 beam hours/year; (2) operation of Loma Linda University (LLU) proton facility for approximately 400 beam hours/year; (3) construction of BAF facility; and (4) collaborative research at HIMAC in Japan and with other existing or potential international facilities. 3. MOA with LLU has been established to provide proton beams with energies of 40-250 important for trapped protons and solar proton events. 4. Limited number of beam hours available at Brookhaven National Laboratory's (BNL) Alternating Gradient Synchrotron (AGS).

Facile synthesis of hollow dendritic Ag/Pt alloy nanoparticles for enhanced methanol oxidation efficiency.

PubMed

Sui, Ning; Wang, Ke; Shan, Xinyao; Bai, Qiang; Wang, Lina; Xiao, Hailian; Liu, Manhong; Colvin, Vicki L; Yu, William W

2017-11-14

Hollow dendritic Ag/Pt alloy nanoparticles were synthesized by a double template method: Ag nanoparticles as the hard template to obtain hollow spheres by a galvanic replacement reaction between PtCl 6 2- and metallic Ag and surfactant micelles (Brij58) as the soft template to generate porous dendrites. The formation of a Ag/Pt alloy phase was confirmed by XRD and HRTEM. Elemental mapping and line scanning revealed the formation of the hollow architecture. We studied the effects of the Ag/Pt ratio, surfactant and reaction temperature on the morphology. In addition, we explored the formation process of hollow dendritic Ag/Pt nanoparticles by tracking the morphologies of the nanostructures formed at different stages. In order to improve the electrocatalytic property, we controlled the size of the nanoparticles and the thickness of the shell by adjusting the amount of the precursor. We found that these Ag/Pt alloy nanoparticles exhibited high activity (440 mA mg -1 ) and stability as an electrocatalyst for catalyzing methanol oxidation.

(Phosphinoalkyl)silanes. 4.(1) Hydrozirconation as a Non-Photochemical Route to (Phosphinopropyl)silanes: Facile Assembly of the Bis(3-(diphenylphosphino)propyl)silyl ("biPSi") Ligand Framework. Access to the Related Poly(3-(dimethylsilyl)propyl)phosphines R(n)()P(CH(2)CH(2)CH(2)SiMe(2)H)(3)(-)(n)() (n = 1, R = Ph; n = 0).

PubMed

Zhou, Xiaobing; Stobart, Stephen R.; Gossage, Robert A.

1997-08-13

Treatment of SiEt(3)(CH=CH(2)) with ZrCp(2)HCl (Schwartz's reagent) followed by reaction with PPh(2)Cl provides a high-yield (75%) route to Ph(2)PCH(2)CH(2)SiEt(3), and accordingly hydrozirconation of CH(2)=CHCH(2)SiHMe(2) affords the intermediate ZrCp(2)(CH(2)CH(2)CH(2)SiHMe(2))Cl (2). The latter, which is very sensitive to hydrolysis and reacts with HCl forming SiHMe(2)Pr(n)() and with NBS or I(2) affording SiHMe(2)CH(2)CH(2)CH(2)X (X = Br (3), I (4)), behaves similarly with PPh(2)Cl, PPhCl(2), or PBr(3) undergoing cleavage to the known Ph(2)PCH(2)CH(2)CH(2)SiMe(2)H (i.e. chelH, A) and the novel bis- and tris(silylpropyl)phosphines PhP(CH(2)CH(2)CH(2)SiMe(2)H)(2) (5) and P(CH(2)CH(2)CH(2)SiMe(2)H)(3) (6), respectively, with concomitant formation of ZrCp(2)Cl(2). Corresponding hydroboration of allylsilanes is facile, but subsequent phosphine halide cleavage yields (phosphinoalkyl)silanes only as constituents of intractable mixtures. Hydrozirconation followed by phosphination with PPh(2)Cl also converts SiHMe(CH(2)CH=CH(2))(2) to SiHMe(CH(2)CH(2)CH(2)PPh(2))(2) (i.e. biPSiH, B) together with a propyl analogue Ph(2)PCH(2)CH(2)CH(2)SiMe(Pr(n)())H (7) of A (ca. 2:1 ratio), as well as SiH(CH(2)CH=CH(2))(3) to a mixture (ca. 5:2:1 ratio) of SiH(CH(2)CH(2)CH(2)PPh(2))(3) (i.e. triPSiH, C), a new analogue SiH(Pr(n)())(CH(2)CH(2)CH(2)PPh(2))(2) (8) of B, and a further analogue Ph(2)PCH(2)CH(2)CH(2)SiHPr(n)()(2) (9) of A. A further analogue SiH(2)(CH(2)CH(2)CH(2)PPh(2))(2) (10) of biPSiH (B) is obtained similarly starting from SiH(2)(CH(2)CH=CH(2))(2). Steric control of silylalkyl cleavage from 2 is indicated by the fact that, like PPh(2)Cl (which forms B), two further biPSiH analogues SiH(Me)[CH(2)CH(2)CH(2)P(n-hex)(2)](2) (11) and SiH(Me)(CH(2)CH(2)CH(2)PPhBz)(2) (12) were obtained using P(n-hex)(2)Cl (i.e. n-hex = CH(3)(CH(2))(4)CH(2)-) or PPhBzCl (i.e. Bz = -CH(2)C(6)H(5)), respectively, whereas neither PPr(i)(2)Cl nor PBu(t)(2)Cl led to (phosphinoalkyl)silane formation

Charge transfer photodissociation of phenol on Ag(111)

NASA Astrophysics Data System (ADS)

Lee, Junseok; Ryu, Sunmin; Ku, Jong Seok; Kim, Seong Keun

2001-12-01

The photochemistry of phenol on Ag(111) has been investigated by post-irradiation temperature programmed desorption (TPD). Ultraviolet (UV) irradiation at 355 and 266 nm was found to affect only the chemisorption layer in direct contact with the metal surface, while leaving the multilayer virtually intact. The main photoinduced reaction was found to be photodissociation of the O-H bond of phenol. Two new peaks were observed at the mass of phenol in the post-irradiation TPD spectrum at 335 K and 455 K. These peaks were assigned to the recombinative desorption of phenoxy with the hydrogen from O-H bond photodissociation and from thermal C-H bond fission, respectively. The photodissociation cross section was measured at different wavelengths and coverages. A charge transfer type photodissociation mechanism was proposed, where hot electrons generated in the substrate by UV photons attach to the affinity level of the adsorbed phenol. The transition to the transient anionic potential then leads to facile dissociation of O-H bond. The affinity level of phenol has been estimated to lie at 3.2-3.5 eV above the Fermi level for the 1 ML case.

Integrating AgI/AgBr biphasic heterostructures encased by few layer h-BN with enhanced catalytic activity and stability.

PubMed

Wu, Wen; Lv, Xiaomeng; Wang, Jiaxi; Xie, Jimin

2017-06-15

Using freshly prepared water-soluble KBr crystal as facile, low-cost sacrificial template, AgBr nanocubes were synthesized through one-pot precipitation method, then navy bean shaped AgI/AgBr biphasic heterostructures were synthesized through anion-exchange reaction and encased within few-layer h-BN to obtain final product. The obtained heterostructured AgI/AgBr/h-BN composite without plasmonic noble metal nanoparticles was used as stable and high active photocatalyst for dye degradation under visible light irradiation, comparing both with self-prepared normal AgBr, AgBr cubes, AgI/AgBr navy beans and other related catalysts reported in the literature. The significant boosting of activity was attributed to the formation of AgI/AgBr interface and the coupling of few-layer h-BN, the latter of which not only effectively suppresses the reduction of silver ions but greatly enhance the charge separation. Furthermore, it was suggested that the photogenerated holes and superoxide radical were the main active species according to photoelectron chemical measurements, electron spin resonance spin-trap analysis and radical trapping experiments. Finally, the possible mechanism of enhanced photocatalytic activity and stability was discussed and proposed. The work demonstrates that engineering Ag-based semiconductor coupling with h-BN would profit the design strategy for low-cost, solar-driven photocatalysts. Copyright © 2017 Elsevier Inc. All rights reserved.

Ag[Fe(CO)5]2(+) : a bare silver complex with Fe(CO)5 as a ligand.

PubMed

Malinowski, Przemysław J; Krossing, Ingo

2014-12-01

Attempts to prepare Fe(CO)5 (+) from Ag[Al(OR(F) )4 ] (R(F) =C(CF3 )3 ) and Fe(CO)5 in CH2 Cl2 yielded the first complex of a neutral metal carbonyl bound to a simple metal cation. The Ag[Fe(CO)5 ]2 (+) cation consists of two Fe(CO)5 molecules coordinating Ag(+) in an almost linear fashion. The ν(CO) modes are blue-shifted compared to Fe(CO)5 , with one band above 2143 cm(-1) indicating that back-bonding is heavily decreased in the Ag[Fe(CO)5 ]2 (+) cation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Singlet internal conversion processes in the order of 1Bu+→3Ag-→1Bu-→2Ag-→1Ag- in all- trans-spheroidene and lycopene as revealed by subpicosecond time-resolved Raman spectroscopy

NASA Astrophysics Data System (ADS)

Rondonuwu, Ferdy S.; Kakitani, Yoshinori; Tamura, Hiroshi; Koyama, Yasushi

2006-09-01

Key Raman lines ascribable to the 1Bu+, 3Ag-, 1Bu- and 2Ag- states were identified in the subpicosecond time-resolved Raman spectra of spheroidene and lycopene having 10 and 11 conjugated double bonds, respectively. The sequential rise-and-decay of the key Raman lines showed the internal conversion processes of 1Bu+→3Ag-→1Bu-→2Ag-→1Ag- (ground). The time constant in each step of internal conversion reflects the energy gap between the relevant states that had been determined by measurement of resonance - Raman excitation profiles [K. Furuichi, T. Sashima, Y. Koyama, Chem. Phys. Lett. 356 (2002) 547].

Gene Profiling Characteristics of Radioadaptive Response in AG01522 Normal Human Fibroblasts

PubMed Central

Hou, Jue; Wang, Fan; Kong, Peizhong; Yu, Peter K. N.; Wang, Hongzhi; Han, Wei

2015-01-01

Radioadaptive response (RAR) in mammalian cells refers to the phenomenon where a low-dose ionizing irradiation alters the gene expression profiles, and protects the cells from the detrimental effects of a subsequent high dose exposure. Despite the completion of numerous experimental studies on RAR, the underlying mechanism has remained unclear. In this study, we aimed to have a comprehensive investigation on the RAR induced in the AG01522 human fibroblasts first exposed to 5 cGy (priming dose) and then followed by 2 Gy (challenge dose) of X-ray through comparisons to those cells that had only received a single 2 Gy dose. We studied how the priming dose affected the expression of gene transcripts, and to identify transcripts or pathways that were associated with the reduced chromosomal damages (in terms of the number of micronuclei) after application of the challenging dose. Through the mRNA and microRNA microarray analyses, the transcriptome alteration in AG01522 cells was examined, and the significantly altered genes were identified for different irradiation procedures using bioinformatics approaches. We observed that a low-dose X-ray exposure produced an alert, triggering and altering cellular responses to defend against subsequent high dose-induced damages, and accelerating the cell repair process. Moreover, the p53 signaling pathway was found to play critial roles in regulating DNA damage responses at the early stage after application of the challenging dose, particularly in the RAR group. Furthermore, microRNA analyses also revealed that cell communication and intercellular signaling transduction played important roles after low-dose irradiation. We conclude that RAR benefits from the alarm mechanisms triggered by a low-dose priming radation dose. PMID:25886619

Improvement of BCG protective efficacy with a novel chimpanzee adenovirus and a modified vaccinia Ankara virus both expressing Ag85A.

PubMed

Stylianou, E; Griffiths, K L; Poyntz, H C; Harrington-Kandt, R; Dicks, M D; Stockdale, L; Betts, G; McShane, H

2015-11-27

A replication-deficient chimpanzee adenovirus expressing Ag85A (ChAdOx1.85A) was assessed, both alone and in combination with modified vaccinia Ankara also expressing Ag85A (MVA85A), for its immunogenicity and protective efficacy against a Mycobacterium tuberculosis (M.tb) challenge in mice. Naïve and BCG-primed mice were vaccinated or boosted with ChAdOx1.85A and MVA85A in different combinations. Although intranasally administered ChAdOx1.85A induced strong immune responses in the lungs, it failed to consistently protect against aerosol M.tb challenge. In contrast, ChAdOx1.85A followed by MVA85A administered either mucosally or systemically, induced strong immune responses and was able to improve the protective efficacy of BCG. This vaccination regime has consistently shown superior protection over BCG alone and should be evaluated further. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Enhanced Visible Light Photocatalytic Degradation of Organic Pollutants over Flower-Like Bi2O2CO3 Dotted with Ag@AgBr

PubMed Central

Lin, Shuanglong; Wang, Miao; Liu, Li; Liang, Yinghua; Cui, Wenquan; Zhang, Zisheng; Yun, Nan

2016-01-01

A facile and feasible oil-in-water self-assembly approach was developed to synthesize flower-like Ag@AgBr/Bi2O2CO3 micro-composites. The photocatalytic activities of the samples were evaluated through methylene blue degradation under visible light irradiation. Compared to Bi2O2CO3, flower-like Ag@AgBr/Bi2O2CO3 micro-composites show enhanced photocatalytic activities. In addition, results indicate that both the physicochemical properties and associated photocatalytic activities of Ag@AgBr/Bi2O2CO3 composites are shown to be dependent on the loading quantity of Ag@AgBr. The highest photocatalytic performance was achieved at 7 wt % Ag@AgBr, degrading 95.18% methylene blue (MB) after 20 min of irradiation, which is over 1.52 and 3.56 times more efficient than that of pure Ag@AgBr and pure Bi2O2CO3, respectively. Bisphenol A (BPA) was also degraded to further demonstrate the degradation ability of Ag@AgBr/Bi2O2CO3. A photocatalytic mechanism for the degradation of organic compounds over Ag@AgBr/Bi2O2CO3 was proposed. Results from this study illustrate an entirely new approach to fabricate semiconductor composites containing Ag@AgX/bismuth (X = a halogen). PMID:28774002

Oblique view of Facility No. S362 showing the profile of ...

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

Oblique view of Facility No. S362 showing the profile of the ramp. Note the mooring cleat fixed to the top edge of the curb at left - U.S. Naval Base, Pearl Harbor, Seaplane Ramps - World War II Type, Southwest and west shore of Ford Island, near Wasp Boulevard, Pearl City, Honolulu County, HI

Lidar sprectroscopy instrument (LISSI): An infrastructure facility for chemical aerosol profiling at the University of Hertfordshire

NASA Astrophysics Data System (ADS)

Tesche, Matthias; Tatarov, Boyan; Noh, Youngmin; Müller, Detlef

2018-04-01

The lidar development at the University of Hertfordshire explores the feasibility of using Raman backscattering for chemical aerosol profiling. This paper provides an overview of the new facility. A high-power Nd:YAG/OPO setup is used to excite Raman backscattering at a wide range of wavelengths. The receiver combines a spectrometer with a 32-channel detector or an ICCD camera to resolve Raman signals of various chemical compounds. The new facility will open new avenues for chemical profiling of aerosol pollution from measurements of Raman scattering by selected chemical compounds, provide data that allow to close the gap between optical and microphysical aerosol profiling with lidar and enables connecting lidar measurements to parameters used in atmospheric modelling.

Performance testing of a prototype Pd-Ag diffuser

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

Morgan, G. A.; Hodge, B. J.

The fusion fuel cycle has gained significant attention over the last decade as interest in fusion programs has increased. One of the critical components of the fusion process is the tritium fuel cycle. The tritium fuel cycle is designed to supply and recycle process tritium at a specific throughput rate. One of the most important processes within the tritium fuel cycle is the clean-up of the of the process tritium. This step will initially separate the hydrogen isotopes (H2, D2, and T2) from the rest of the process gas using Pd-Ag diffusers or permeators. The Pd-Ag diffuser is an integralmore » component for any tritium purification system; whether part of the United States’ defense mission or fusion programs. Domestic manufacturers of Pd-Ag diffusers are extremely limited and only a few manufacturers exist. Johnson-Matthey (JM) Pd-Ag diffusers (permeators) have previously been evaluated for the separation of hydrogen isotopes from non-hydrogen gas species in the process. JM is no longer manufacturing Pd-Ag diffusers and a replacement vendor needs to be identified to support future needs. A prototype Pd-Ag diffuser has been manufactured by Power and Energy, and is considered a potential replacement for the JM diffuser for tritium service. New diffuser designs for a tritium facility for any fusion energy applications must be characterized by evaluating their operating envelope prior to installation in a tritium processing facility. The prototype Pd-Ag diffuser was characterized to determine the overall performance as a function of the permeation of hydrogen through the membrane. The tests described in this report consider the effects of feed gas compositions, feed flow rates, pump configuration and internal tube pressure on the permeation of H2 through the Pd-Ag tubes.« less

Arpeggio: harmonic compression of ChIP-seq data reveals protein-chromatin interaction signatures

PubMed Central

Stanton, Kelly Patrick; Parisi, Fabio; Strino, Francesco; Rabin, Neta; Asp, Patrik; Kluger, Yuval

2013-01-01

Researchers generating new genome-wide data in an exploratory sequencing study can gain biological insights by comparing their data with well-annotated data sets possessing similar genomic patterns. Data compression techniques are needed for efficient comparisons of a new genomic experiment with large repositories of publicly available profiles. Furthermore, data representations that allow comparisons of genomic signals from different platforms and across species enhance our ability to leverage these large repositories. Here, we present a signal processing approach that characterizes protein–chromatin interaction patterns at length scales of several kilobases. This allows us to efficiently compare numerous chromatin-immunoprecipitation sequencing (ChIP-seq) data sets consisting of many types of DNA-binding proteins collected from a variety of cells, conditions and organisms. Importantly, these interaction patterns broadly reflect the biological properties of the binding events. To generate these profiles, termed Arpeggio profiles, we applied harmonic deconvolution techniques to the autocorrelation profiles of the ChIP-seq signals. We used 806 publicly available ChIP-seq experiments and showed that Arpeggio profiles with similar spectral densities shared biological properties. Arpeggio profiles of ChIP-seq data sets revealed characteristics that are not easily detected by standard peak finders. They also allowed us to relate sequencing data sets from different genomes, experimental platforms and protocols. Arpeggio is freely available at http://sourceforge.net/p/arpeggio/wiki/Home/. PMID:23873955

Arpeggio: harmonic compression of ChIP-seq data reveals protein-chromatin interaction signatures.

PubMed

Stanton, Kelly Patrick; Parisi, Fabio; Strino, Francesco; Rabin, Neta; Asp, Patrik; Kluger, Yuval

2013-09-01

Researchers generating new genome-wide data in an exploratory sequencing study can gain biological insights by comparing their data with well-annotated data sets possessing similar genomic patterns. Data compression techniques are needed for efficient comparisons of a new genomic experiment with large repositories of publicly available profiles. Furthermore, data representations that allow comparisons of genomic signals from different platforms and across species enhance our ability to leverage these large repositories. Here, we present a signal processing approach that characterizes protein-chromatin interaction patterns at length scales of several kilobases. This allows us to efficiently compare numerous chromatin-immunoprecipitation sequencing (ChIP-seq) data sets consisting of many types of DNA-binding proteins collected from a variety of cells, conditions and organisms. Importantly, these interaction patterns broadly reflect the biological properties of the binding events. To generate these profiles, termed Arpeggio profiles, we applied harmonic deconvolution techniques to the autocorrelation profiles of the ChIP-seq signals. We used 806 publicly available ChIP-seq experiments and showed that Arpeggio profiles with similar spectral densities shared biological properties. Arpeggio profiles of ChIP-seq data sets revealed characteristics that are not easily detected by standard peak finders. They also allowed us to relate sequencing data sets from different genomes, experimental platforms and protocols. Arpeggio is freely available at http://sourceforge.net/p/arpeggio/wiki/Home/.

Template-free synthesis of cube-like Ag/AgCl nanostructures via a direct-precipitation protocol: highly efficient sunlight-driven plasmonic photocatalysts.

PubMed

Zhu, Mingshan; Chen, Penglei; Ma, Wanhong; Lei, Bin; Liu, Minghua

2012-11-01

In this paper, we report that cube-like Ag/AgCl nanostructures could be facilely fabricated in a one-pot manner through a direct-precipitation protocol under ambient conditions, wherein no additional issues such as external energy (e.g., high temperature or high pressure), surfactants, or reducing agents are required. In terms of using sodium chloride (NaCl) as chlorine source and silver acetate (CH₃COOAg) as silver source, it is disclosed that simply by adding an aqueous solution of NaCl into an aqueous solution of CH₃COOAg, Ag/AgCl nanostructures with a cube-like geometry, could be successfully formulated. We show that thus-formulated cube-like Ag/AgCl nanospecies could be used as high-performance yet durable visible-light-driven or sunlight-driven plasmonic photocatalysts for the photodegradation of methyl orange (MO) and 4-chlorophenol (4-CP) pollutants. Compared with the commercially available P25-TiO₂, and the Ag/AgCl nanospheres previously fabricated via a surfactant-assisted method, our current cube-like Ag/AgCl nanostructures could exhibit much higher photocatalytic performance. Our template free protocol might open up new and varied opportunities for an easy synthesis of cube-like Ag/AgCl-based high-performance sunlight-driven plasmonic photocatalysts for organic pollutant elimination.

Comparisons of the error budgets associated with ground-based FTIR measurements of atmospheric CH4 profiles at Île de la Réunion and Jungfraujoch.

NASA Astrophysics Data System (ADS)

Vanhaelewyn, Gauthier; Duchatelet, Pierre; Vigouroux, Corinne; Dils, Bart; Kumps, Nicolas; Hermans, Christian; Demoulin, Philippe; Mahieu, Emmanuel; Sussmann, Ralf; de Mazière, Martine

2010-05-01

The Fourier Transform Infra Red (FTIR) remote measurements of atmospheric constituents at the observatories at Saint-Denis (20.90°S, 55.48°E, 50 m a.s.l., Île de la Réunion) and Jungfraujoch (46.55°N, 7.98°E, 3580 m a.s.l., Switzerland) are affiliated to the Network for the Detection of Atmospheric Composition Change (NDACC). The European NDACC FTIR data for CH4 were improved and homogenized among the stations in the EU project HYMN. One important application of these data is their use for the validation of satellite products, like the validation of SCIAMACHY or IASI CH4 columns. Therefore, it is very important that errors and uncertainties associated to the ground-based FTIR CH4 data are well characterized. In this poster we present a comparison of errors on retrieved vertical concentration profiles of CH4 between Saint-Denis and Jungfraujoch. At both stations, we have used the same retrieval algorithm, namely SFIT2 v3.92 developed jointly at the NASA Langley Research Center, the National Center for Atmospheric Research (NCAR) and the National Institute of Water and Atmosphere Research (NIWA) at Lauder, New Zealand, and error evaluation tools developed at the Belgian Institute for Space Aeronomy (BIRA-IASB). The error components investigated in this study are: smoothing, noise, temperature, instrumental line shape (ILS) (in particular the modulation amplitude and phase), spectroscopy (in particular the pressure broadening and intensity), interfering species and solar zenith angle (SZA) error. We will determine if the characteristics of the sites in terms of altitude, geographic locations and atmospheric conditions produce significant differences in the error budgets for the retrieved CH4 vertical profiles

Copper-Catalyzed, Directing Group-Assisted Fluorination of Arene and Heteroarene C-H Bonds

PubMed Central

Truong, Thanh; Klimovica, Kristine; Daugulis, Olafs

2013-01-01

We have developed a method for direct, copper-catalyzed, auxiliary-assisted fluorination of β-sp2 C-H bonds of benzoic acid derivatives and γ-sp2 C-H bonds of α,α-disubstituted benzylamine derivatives. The reaction employs CuI catalyst, AgF fluoride source, and DMF, pyridine, or DMPU solvent at moderately elevated temperatures. Selective mono- or difluorination can be achieved by simply changing reaction conditions. The method shows excellent functional group tolerance and provides a straightforward way for the preparation of ortho-fluorinated benzoic acids. PMID:23758609

Tree CH4 fluxes in forestry drained peatland in southern Finland

NASA Astrophysics Data System (ADS)

Haikarainen, Iikka; Putkinen, Anuliina; Pyykkö, Petteri; Halmeenmäki, Elisa; Pihlatie, Mari

2017-04-01

Methane (CH4) is among the most important greenhouse gases and its atmospheric concentration is increasing. Boreal forests are commonly considered a net sink of atmospheric CH4 due to CH4 consuming bacteria in aerated soil layers. Recent studies have, however, demonstrated that trees are capable of emitting CH4 from their stems and shoots by transporting anaerobically produced CH4 from deeper soil layers to the atmosphere. Furthermore, trees may act as independent sources of CH4. We have measured tree stem CH4 exchange of boreal tree species at Lettosuo, a nutrient rich peatland forest in Tammela, southern Finland (60˚ 38' N, 23˚ 57' E), using the static chamber technique. Three species, downy birch (Betula pubescens), Norway spruce (Picea abies) and Scots pine (Pinus sylvestris), were selected under investigation as they represent common boreal tree species. Fluxes of CH4 were measured during 7.6.2016 - 17.10.2016 from in total 25 sample trees growing on two different plots: a treatment plot where all the pines were removed to raise the water table level (WTL) and a control plot. Three birches from the treatment plot were selected to measure CH4 flux variation within vertical profile of the trees. Characterization of microbial communities, quantification of methanogenic and methanotrophic functional genes, and measurements of potential CH4 production and consumption from peat profile and forest floor moss samples were also carried out to obtain insight to the CH4 flux dynamics at the studied sites. The pine removal treatment did not markedly change the average WTL, but it made the WTL more variable with frequently 10-15 cm closer to soil surface compared to the WTL on the control plot. We found small and variable CH4 emissions from the stems of trees on both of the plots, while occasional consumption of CH4 was also present. Generally the CH4 emissions were higher and more dominant at the treatment plot compared to the control plot, and the fluxes were

One-pot synthesis of ternary Ag₂CO₃/Ag/AgCl photocatalyst in natural geothermal water with enhanced photocatalytic activity under visible light irradiation.

PubMed

Yao, Xiaxi; Liu, Xiaoheng

2014-09-15

Geothermal water is a clean, cheap and renewable resource and it is widely distributed all over the world. In this work, ternary Ag2CO3/Ag/AgCl photocatalyst has been successfully synthesized via a one-pot precipitation method in natural geothermal water at room temperature, wherein the geothermal water serves as the source of chlorine and carbonate. The results suggest that the Ag/AgCl nanoparticles are anchored on the surface of Ag2CO3 and Ag2CO3/Ag/AgCl composite shows strong absorption ability in the visible light region. The evaluation of the photocatalytic activity indicates that the as-synthesized Ag2CO3/Ag/AgCl photocatalyst exhibits higher photocatalytic performance for the degradation of methylene blue (MB) aqueous solution under visible light irradiation than one-component (Ag2CO3), two-component (Ag/AgCl, Ag2CO3/AgCl) and the mechanical mixture of Ag2CO3 and Ag/AgCl. The trapping experiments confirmed that holes (h(+)) and (•)O2(-) were the two main active species in the photocatalytic process. Finally, a possible Z-scheme photocatalytic mechanism of the charge transfer was proposed for the enhanced photocatalytic performance. This work may open up new insights into the application of cheap geothermal water resources in the word and provide new opportunities for facile fabrication of Ag/AgCl-based photocatalysts. Copyright © 2014 Elsevier B.V. All rights reserved.

Infrared extinction and microwave absorption properties of hybrid Fe3O4@SiO2@Ag nanospheres synthesized via a facile seed-mediated growth route.

PubMed

Chen, Yongpeng; Li, Shichuan; Wei, Xuebin; Tang, Runze; Zhou, Zunning

2018-06-21

Fe3O4@SiO2@Ag ternary hybrid nanoparticles were synthesized via a facile seed-mediated growth route. X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) measurements were used to characterize the as-prepared product. The results indicated that the nanoparticles exhibited excellent magnetic properties and an extremely dense structure with Ag layer thicknesses of 30 nm, 40 nm, and 50 nm. Furthermore, the microwave shielding effectiveness exceeded 20 dB over almost the entire frequency range (2-18 GHz), and the effectiveness obviously improved as the thickness of the Ag layer increased. In addition, the IR extinction coefficient of the nanoparticles was calculated by a finite-difference time-domain (FDTD) method, which showed that the nanoparticles can inherit the extinction performance of pure silver when the Ag shell thickness was 30 nm. Specifically, after assembling into chains, the peak position of the IR extinction curves displayed a significant redshift and an intensity increase as the number of nanoparticles increased in the chain, which dramatically promoted the IR extinction capability. As a result, the Fe3O4@SiO2@Ag nanoparticles are expected to be used as a new multispectral interference material. © 2018 IOP Publishing Ltd.

AGS vertical beta function measurements for Run 15

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

Harper, C.; Ahrens, L.; Huang, H.

2016-10-07

One key parameter for running the AGS efficiently is by maintaining a low emittance. To measure emittance, one needs to measure the beta function throughout the cycle. This can be done by measuring the beta function at the ionization profile monitors (IPM) in the AGS. This tech note delves into the motivation, the measurement, and some strides that were made throughout Run15.

Facile synthesis of Ag@ZIF-8 core-shell heterostructure nanowires for improved antibacterial activities

NASA Astrophysics Data System (ADS)

Guo, Yu-Feng; Fang, Wei-Jun; Fu, Jie-Ru; Wu, Yun; Zheng, Jun; Gao, Gui-Qi; Chen, Cheng; Yan, Rui-Wen; Huang, Shou-Guo; Wang, Chun-Chang

2018-03-01

Compared with pure MOFs, core-shell heterostructures of noble-metal@MOFs have attracted tremendous interest due to their unique structure and extensive applications. In the present study, we have successfully synthesized well-defined core-shell Ag@ZIF-8 nanowires. The products growth process has been investigated by examining the products obtained at different intervals and the thickness of ZIF-8 shell ranging from 30 to 100 nm can be technically obtained by tuning the quantity of Ag nanowires. Ag@ZIF-8 has been proven to possess large specific surfaces and high thermal stability. Additionally, the antibacterial activity of Ag@ZIF-8 is further tested against Bacillus subtilis and Escherichia coli BL21. The results reveal that Ag@ZIF-8 core-shell heterostructure nanowires have effective activities against the two types of bacterial strains.

Facile low-temperature one-step synthesis of pomelo peel biochar under air atmosphere and its adsorption behaviors for Ag(I) and Pb(II).

PubMed

Zhao, Tuo; Yao, Ying; Li, Danrong; Wu, Feng; Zhang, Cunzhong; Gao, Bin

2018-05-29

This study prepared a novel low-cost surface functionalized carbon adsorbent (PPC) from biomass waste (pomelo peel) through a facile low-temperature (250 °C) one-step method under regular air atmosphere. The adsorption performance and mechanism of the carbon material for Ag(I) and Pb(II) were investigated by a range of sorption experiments and characterizations including SEM, EDX, XRD and FTIR. Sorption experimental results suggested that PPC had high adsorption capacities of 137.4 and 88.7 mg/g for Ag(I) and Pb(II), respectively, with adsorbent dosage of 2 g/L at unadjusted solution pH and room temperature (23 ± 1 °C). The characterization results indicated high-efficiency removal of the heavy metals by PPC was attributed to the strong chemical adsorption involving that Ag(I) ions were reduced as metallic Ag particles by oxygenic functional groups and Pb(II) ions were precipitated as Pb 5 (PO 4 ) 3 OH crystals by phosphorous functional groups on the carbon surfaces. This study provides the possibility of synthesis high-efficient adsorbent using economic and environmental-friendly approach with low energy consumption. Copyright © 2018 Elsevier B.V. All rights reserved.

Formation and properties of hyaluronan/nano Ag and hyaluronan-lecithin/nano Ag films.

PubMed

Khachatryan, Gohar; Khachatryan, Karen; Grzyb, Jacek; Fiedorowicz, Maciej

2016-10-20

A facile and environmentally friendly method of the preparation of silver nanoparticles embedded in hyaluronan (Hyal/Ag) and hyaluronan-lecithin (Hyal-L/Ag) matrix was developed. Thin, elastic foils were prepared from gels by an in situ synthesis of Ag in an aqueous solution of sodium hyaluronate (Hyal), using aq. d-(+)-xylose solution as a reducing agent. The gels were applied to a clean, smooth, defatted Teflon surface and left for drying in the air. The dry foils were stored in a closed container. UV-vis spectroscopy, transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectra confirmed formation of about 10nm ball-shaped Ag nanoparticles situated within the polysaccharide template. Thermal properties of the composites were characterized involving differential scanning calorimetry (DSC) and thermogravimetric (TGA) analyses, whereas molecular weights of polysaccharide chains of the matrix were estimated with the size exclusion chromatography coupled with multiangle laser light scattering and refractometric detectors (HPSEC-MALLS-RI). An increase in the molecular weight of the hyaluronate after generation of Ag nanoparticles was observed. The foils showed specific properties. The study confirmed that silver nanoparticles can be successfully prepared with environmentally friendly method, using hyaluronan as a stabilizing template. Hyaluronan and hyaluronan-lecithin matrices provide nanocrystals uniform in size and shape. The composites demonstrated a bacteriostatic activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Novel ternary g-C3N4/Ag3VO4/AgBr nanocomposites with excellent visible-light-driven photocatalytic performance for environmental applications

NASA Astrophysics Data System (ADS)

Barzegar, Javid; Habibi-Yangjeh, Aziz; Akhundi, Anise; Vadivel, S.

2018-04-01

Novel visible-light-induced photocatalysts were fabricated by integration of Ag3VO4 and AgBr semiconductors with graphitic carbon nitride (g-C3N4) through a facile refluxing method. The fabricated photocatalysts were extensively characterized by XRD, EDX, SEM, TEM, FT-IR, UV-vis DRS, BET, TGA, and PL instruments. The photocatalytic performance of these samples was studied by degradations of three dye contaminants under visible-light exposure. Among the ternary photocatalysts, the g-C3N4/Ag3VO4/AgBr (10%) nanocomposite displayed the maximum activity for RhB degradation with rate constant of 1366.6 × 10-4 min-1, which is 116, 7.23, and 38.5 times as high as those of the g-C3N4, g-C3N4/AgBr (10%), and g-C3N4/Ag3VO4 (30%) photocatalysts, respectively. The effects of synthesis time and calcination temperature were also investigated and discussed. Furthermore, according to the trapping experiments, it was found that superoxide anion radicals were the predominant reactive species in this system. Finally, the ternary photocatalyst displayed superlative activity in removal of the contaminants under visible-light exposure, displaying great potential of this ternary photocatalyst for environmental remediation, because of a facile synthesis route and outstanding photocatalytic performance.

An in-situ synthesis of Ag/AgCl/TiO2/hierarchical porous magnesian material and its photocatalytic performance

PubMed Central

Yang, Lu; Wang, Fazhou; Shu, Chang; Liu, Peng; Zhang, Wenqin; Hu, Shuguang

2016-01-01

The absorption ability and photocatalytic activity of photocatalytic materials play important roles in improving the pollutants removal effects. Herein, we reported a new kind of photocatalytic material, which was synthesized by simultaneously designing hierarchical porous magnesian (PM) substrate and TiO2 catalyst modification. Particularly, PM substrate could be facilely prepared by controlling its crystal phase (Phase 5, Mg3Cl(OH)5·4H2O), while Ag/AgCl particles modification of TiO2 could be achieved by in situ ion exchange between Ag+ and above crystal Phase. Physiochemical analysis shows that Ag/AgCl/TiO2/PM material has higher visible and ultraviolet light absorption response, and excellent gas absorption performance compared to other controls. These suggested that Ag/AgCl/TiO2/PM material could produce more efficient photocatalytic effects. Its photocatalytic reaction rate was 5.21 and 30.57 times higher than that of TiO2/PM and TiO2/imporous magnesian substrate, respectively. Thus, this material and its intergration synthesis method could provide a novel strategy for high-efficiency application and modification of TiO2 photocatalyst in engineering filed. PMID:26883972

Facile fabrication of Ag nanowires for capacitive flexible pressure sensors by liquid polyol reduction method

NASA Astrophysics Data System (ADS)

Wei, Xiongbang; Quan, Yong; Zeng, Hongjuan; Huang, Wen; Li, Weizhi; Liao, Jiaxuan; Chen, Zhi

2018-01-01

The Ag nanowires (AgNWs) were prepared by improved liquid polyol reduction method, and the AgNWs were successfully applied to the capacitive flexible pressure sensors. Firstly, the one-dimensional radial growth conditions of AgNWs were optimized from four aspects of the molecular weight of the protective agent polyvinyl pyrrolidone (PVP), the molar ratio of AgNO3 and PVP, the anion concentration of the metal salt and the reaction temperature. The effect of polymerization degree of protective agent on one-dimensional radial growth of AgNWs was investigated by using three kinds of protective agents PVP-K-30, PVP-K-60 and PVP-K-90. Three different AgNO3 and PVP molar ratios of 1:1, 1:3 and 1:9 were designed, and the effects of PVP adsorption capacity on one-dimensional radial growth of AgNWs were investigated. Three concentrations of 0 mM NaCl, 16 mM NaCl and 32 mM NaCl were designed to study the effects of anion concentration of the metal salt on the nucleation and etching of silver nanoparticles. The effects of reaction temperature on the growth of AgNWs were studied at three different temperatures of 140 °C, 160 °C and 180 °C, and appropriate temperature design was proposed. In this experiment, the products of AgNWs prepared under various conditions were analyzed by UV-vis Spectrum and SEM, and the experimental conditions were optimized from the synthesis mechanism and reaction conditions.

ChIP-seq: advantages and challenges of a maturing technology.

PubMed

Park, Peter J

2009-10-01

Chromatin immunoprecipitation followed by sequencing (ChIP-seq) is a technique for genome-wide profiling of DNA-binding proteins, histone modifications or nucleosomes. Owing to the tremendous progress in next-generation sequencing technology, ChIP-seq offers higher resolution, less noise and greater coverage than its array-based predecessor ChIP-chip. With the decreasing cost of sequencing, ChIP-seq has become an indispensable tool for studying gene regulation and epigenetic mechanisms. In this Review, I describe the benefits and challenges in harnessing this technique with an emphasis on issues related to experimental design and data analysis. ChIP-seq experiments generate large quantities of data, and effective computational analysis will be crucial for uncovering biological mechanisms.

Degradation of microcystin-LR by highly efficient AgBr/Ag3PO4/TiO2 heterojunction photocatalyst under simulated solar light irradiation

NASA Astrophysics Data System (ADS)

Wang, Xin; Utsumi, Motoo; Yang, Yingnan; Li, Dawei; Zhao, Yingxin; Zhang, Zhenya; Feng, Chuanping; Sugiura, Norio; Cheng, Jay Jiayang

2015-01-01

A novel photocatalyst AgBr/Ag3PO4/TiO2 was developed by a simple facile in situ deposition method and used for degradation of mirocystin-LR. TiO2 (P25) as a cost effective chemical was used to improve the stability of AgBr/Ag3PO4 under simulated solar light irradiation. The photocatalytic activity tests for this heterojunction were conducted under simulated solar light irradiation using methyl orange as targeted pollutant. The results indicated that the optimal Ag to Ti molar ratio for the photocatalytic activity of the resulting heterojunction AgBr/Ag3PO4/TiO2 was 1.5 (named as 1.5 BrPTi), which possessed higher photocatalytic capacity than AgBr/Ag3PO4. The 1.5 BrPTi heterojunction was also more stable than AgBr/Ag3PO4 in photocatalysis. This highly efficient and relatively stable photocatalyst was further tested for degradation of the hepatotoxin microcystin-LR (MC-LR). The results suggested that MC-LR was much more easily degraded by 1.5 BrPTi than by AgBr/Ag3PO4. The quenching effects of different scavengers proved that reactive h+ and •OH played important roles for MC-LR degradation.

Synergistic influence of polyoxometalate surface corona towards enhancing the antibacterial performance of tyrosine-capped Ag nanoparticles

NASA Astrophysics Data System (ADS)

Daima, Hemant K.; Selvakannan, P. R.; Kandjani, Ahmad E.; Shukla, Ravi; Bhargava, Suresh K.; Bansal, Vipul

2013-12-01

with AgNPs, the surface corona of POMs enhances the physical damage to the bacterial cells due to synergistic antibacterial action of AgNPs and POMs, and the ability of tyrosine-reduced AgNPs (AgNPsY) to act as an excellent carrier and stabiliser for the POMs. The further extension of this study towards Gram positive bacterium Staphylococcus albus showed a similar toxicity pattern, whereas these nanomaterials were found to be biocompatible for PC3 epithelial mammalian cells, suggesting the potential of these materials towards specific antimicrobial targeting for topical wound healing applications. The outcomes of this work show that facile tailorability of nanostructured surfaces may play a considerable role in controlling the biological activities of different nanomaterials. Electronic supplementary information (ESI) available: XRD analysis (Fig. S1); cytotoxicity profile (Fig. S2) and optical images of human PC3 cells (Fig. S3) treated with nanomaterials; FTIR vibrational modes arising from different materials (Table S1); and relative concentrations of Ag and POMs present in modified AgNPs used for biological studies (Table S2). See DOI: 10.1039/c3nr03806h

Synergistic Heterobimetallic Manifold for Expedient Manganese(I)-Catalyzed C-H Cyanation.

PubMed

Liu, Weiping; Richter, Sven C; Mei, Ruhuai; Feldt, Milica; Ackermann, Lutz

2016-12-12

The manganese-catalyzed cyanation of inert C-H bonds was achieved within a heterobimetallic catalysis regime. The manganese(I) catalysis proved widely applicable and enabled C-H cyanations on indoles, pyrroles and thiophenes by facile C-H manganesation. The robustness of the manganese catalyst set the stage for the racemization-free C-H cyanation of amino acids with excellent levels of positional and chemo selectivity by the new cyanating agent NCFS. Experimental and computational mechanistic studies provided strong support for a synergistic heterobimetallic activation mode, facilitating the key C-C formation. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facile synthesis of microporous SiO2/triangular Ag composite nanostructures for photocatalysis

NASA Astrophysics Data System (ADS)

Sirohi, Sidhharth; Singh, Anandpreet; Dagar, Chakit; Saini, Gajender; Pani, Balaram; Nain, Ratyakshi

2017-11-01

In this article, we present a novel fabrication of microporous SiO2/triangular Ag nanoparticles for dye (methylene blue) adsorption and plasmon-mediated degradation. Microporous SiO2 nanoparticles with pore size <2 nm were synthesized using cetyltrimethylammonium bromide as a structure-directing agent and functionalized with APTMS ((3-aminopropyl) trimethoxysilane) to introduce amine groups. Amine-functionalized microporous silica was used for adsorption of triangular silver (Ag) nanoparticles. The synthesized microporous SiO2 nanostructures were investigated for adsorption of different dyes including methylene blue, congo red, direct green 26 and curcumin crystalline. Amine-functionalized microporous SiO2/triangular Ag nanostructures were used for plasmon-mediated photocatalysis of methylene blue. The experimental results revealed that the large surface area of microporous silica facilitated adsorption of dye. Triangular Ag nanoparticles, due to their better charge carrier generation and enhanced surface plasmon resonance, further enhanced the photocatalysis performance.

Synthesis and characterization of novel plasmonic Ag/AgX-CNTs (X = Cl, Br, I) nanocomposite photocatalysts and synergetic degradation of organic pollutant under visible light.

PubMed

Shi, Huixian; Chen, Jiangyao; Li, Guiying; Nie, Xin; Zhao, Huijun; Wong, Po-Keung; An, Taicheng

2013-08-14

A series of novel well-defined Ag/AgX (X = Cl, Br, I) loaded carbon nanotubes (CNTs) composite photocatalysts (Ag/AgX-CNTs) were fabricated for the first time via a facile ultrasonic assistant deposition-precipitation method at the room temperature (25 ± 1 °C). X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption analysis, scanning electron microscopy, and ultraviolet-visible light absorption spectra analysis were used to characterize the structure, morphology, and optical properties of the as-prepared photocatalysts. Results confirmed the existence of the direct interfacial contact between Ag/AgX nanoparticles and CNTs, and Ag/AgX-CNTs nanocomposites exhibit superior absorbance in the visible light (VL) region owing to the surface plasmon resonance (SPR) of Ag nanoparticles. The fabricated composite photocatalysts were employed to remove 2,4,6-tribromophenol (TBP) in aqueous phase. A remarkably enhanced VL photocatalytic degradation efficiency of Ag/AgX-CNTs nanocomposites was observed when compared to that of pure AgX or CNTs. The photocatalytic activity enhancement of Ag/AgX-CNTs was due to the effective electron transfer from photoexcited AgX and plasmon-excited Ag(0) nanoparticles to CNTs. This can effectively decrease the recombination of electron-hole pairs, lead to a prolonged lifetime of the photoholes that promotes the degradation efficiency.

Facile synthesis of porous bimetallic alloyed PdAg nanoflowers supported on reduced graphene oxide for simultaneous detection of ascorbic acid, dopamine, and uric acid.

PubMed

Chen, Li-Xian; Zheng, Jie-Ning; Wang, Ai-Jun; Wu, Lan-Ju; Chen, Jian-Rong; Feng, Jiu-Ju

2015-05-07

Porous bimetallic alloyed palladium silver (PdAg) nanoflowers supported on reduced graphene oxide (PdAg NFs/rGO) were prepared via a facile and simple in situ reduction process, with the assistance of cetyltrimethylammonium bromide as a structure directing agent. The as-prepared nanocomposite modified glassy carbon electrode (PdAg NFs/rGO/GCE) showed enhanced catalytic currents and enlarged peak potential separations for the oxidation of ascorbic acid (AA), dopamine (DA), and uric acid (UA) as compared to those of PdAg/GCE, rGO/GCE, commercial Pd/C/GCE, and bare GCE. The as-developed sensor can selectively detect AA, DA, and UA with a good anti-interference ability, wide concentration ranges of 1.0 μM-2.1 mM, 0.4-96.0 μM, and 1.0-150.0 μM, respectively, together with low detection limits of 0.057, 0.048, and 0.081 μM (S/N = 3), respectively. For simultaneous detection of AA, DA, and UA, the linear current-concentration responses were observed from 1.0 μM-4.1 mM, 0.05-112.0 μM, and 3.0-186.0 μM, with the detection limits of 0.185, 0.017, and 0.654 μM (S/N = 3), respectively.

H α and H β Raman scattering line profiles of the symbiotic star AG Pegasi

NASA Astrophysics Data System (ADS)

Lee, Seong-Jae; Hyung, Siek

2018-04-01

The H α and H β line profiles of the symbiotic star AG Pegasi, observed in 1998 September (phase ϕ = 10.24), display top narrow double Gaussian components and bottom broad components (FWHM = 200-400 km s-1). The photoionization model indicates that the ionized zone, responsible for the hydrogen Balmer and Lyman lines, is radiation-bounded, with a hydrogen gas number density of nH ˜ 109.85 cm-3 and a gas temperature of Te = 12 000-15 000 K. We have carried out Monte Carlo simulations to fit the Raman scattering broad wings, assuming that the hydrogen Ly β and Ly γ lines emitted within the radiation-bounded H II zone around a white dwarf have the same double Gaussian line profile shape as the hydrogen Balmer lines. The simulation shows that the scattering H I zones are attached to (or located just outside) the inner H II shells. The best fit to the observed broad H I line profiles indicates that the column density of the scattering neutral zone is NH ≃ 3-5 × 1019 cm-2. We have examined whether the geometrical structure responsible for the observed H α and H β line profiles is a bipolar conical shell structure, consisting of the radiation-bounded ionized zone and the outer material bounded neutral zone. The expanding bipolar structure might be two opposite regions of the common envelope or the outer shell of the Roche lobe around the hot white dwarf, formed through the mass inflows from the giant star and pushed out by the fast winds from the hot white dwarf.

Instability growth seeded by oxygen in CH shells on the National Ignition Facility

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

Haan, S. W., E-mail: haan1@llnl.gov; Johnson, M. A.; Stadermann, M.

Fusion targets imploded on the National Ignition Facility are subject to hydrodynamic instabilities. These have generally been assumed to be seeded primarily by surface roughness, as existing work had suggested that internal inhomogeneity was small enough not to contribute significantly. New simulations presented here examine this in more detail, and consider modulations in internal oxygen content in CH plastic ablators. The oxygen is configured in a way motivated by measurement of oxygen in the shells. We find that plausible oxygen nonuniformity, motivated by target characterization experiments, seeds instability growth that is 3–5× bigger than expected from surface roughness. Pertinent existingmore » capsule characterization is discussed, which suggests the presence of internal modulations that could be oxygen at levels large enough to be the dominant seed for hydrodynamic instability growth. Oxygen-seeded growth is smaller for implosions driven by high-foot pulse shapes, consistent with the performance improvement seen with these pulse shapes. Growth is somewhat smaller for planned future pulse shapes that were optimized to minimize growth of surface ripples. A possible modified specification for oxygen modulations is discussed, which is about 1/5 of the current requirement.« less

Morbidity profile of elderly outpatients attending selected sub-district Siddha health facilities in Tamil Nadu, India

PubMed Central

Selvaraj, Kalaiselvi; Srinivasan, Manikandan; Duraisamy, Venkatachalam; Ramaswamy, Gomathi; Venugopal, Vinayagamurthy; Chinnakali, Palanivel

2016-01-01

Background: Recently, under National Health Mission alternate systems of Medicine are mainstreamed in public health care system. Effective action plan generation, logistic arrangement and roll out of these alternate systems of Medicine needs understanding on profile of morbidities among attendees who come to these facilities. Objectives: This study was planned to report profile of morbidities, age and sex differentials in specific morbidities among geriatric attendees in secondary level siddha health facilities. Materials and Methods: A facility based cross sectional study was conducted among elderly person (60 years and above) attending Siddha outpatient department (OPD) from two of the randomly selected sub district level siddha facilities in Erode district, Tamil Nadu, India. Information on socio-demographic variables like age, gender, education and clinical profile (diagnosis) were collected from records already maintained in the siddha OPD. Morbidities were summarized in terms of proportions based on age and gender. Age and sex specific differentials on specific morbidities were compared using ‘z’ test. Results: Of 2710 patients who visited these two siddha facilities during the reference period, 763 (28.1%) patients were elderly. Arthritis (45.2%), neuritis (8.8%), diabetes (6.6%), bronchial asthma (5.2%), hemiplegia (3.7%) were the top five morbidities diagnosed and treated among elderly attending the siddha OPD. There was a predilection towards elderly male for morbidities such as bronchial asthma and hemiplegia compared to elderly female. Similarly, higher proportions of lumbar spondylosis, hypertension and fungal skin diseases were reported among aged 80 years or more compared to elderly aged 60-79 years. Conclusion: Elderly constitute more than one fourth of outpatients load from siddha health facilities. Degenerative diseases like arthritis and non-communicable diseases were the common morbidities in this age group. Geriatric clinics and mobile

Degraded Land Restoration in Reinstating CH4 Sink

PubMed Central

Singh, Jay Shankar; Gupta, Vijai K.

2016-01-01

Methane (CH4), a potent greenhouse gas, contributes about one third to the global green house gas emissions. CH4-assimilating microbes (mostly methanotrophs) in upland soils play very crucial role in mitigating the CH4 release into the atmosphere. Agricultural, environmental, and climatic shifts can alter CH4 sink profiles of soils, likely through shifts in CH4-assimilating microbial community structure and function. Landuse change, as forest and grassland ecosystems altered to agro-ecosystems, has already attenuated the soil CH4 sink potential, and are expected to be continued in the future. We hypothesized that variations in CH4 uptake rates in soils under different landuse practices could be an indicative of alterations in the abundance and/or type of methanotrophic communities in such soils. However, only a few studies have addressed to number and methanotrophs diversity and their correlation with the CH4 sink potential in soils of rehabilitated/restored lands. We focus on landuse practices that can potentially mitigate CH4 gas emissions, the most prominent of which are improved cropland, grazing land management, use of bio-fertilizers, and restoration of degraded lands. In this perspective paper, it is proposed that restoration of degraded lands can contribute considerably to improved soil CH4 sink strength by retrieving/conserving abundance and assortment of efficient methanotrophic communities. We believe that this report can assist in identifying future experimental directions to the relationships between landuse changes, methane-assimilating microbial communities and soil CH4 sinks. The exploitation of microbial communities other than methanotrophs can contribute significantly to the global CH4 sink potential and can add value in mitigating the CH4 problems. PMID:27379053

Degraded Land Restoration in Reinstating CH4 Sink.

PubMed

Singh, Jay Shankar; Gupta, Vijai K

2016-01-01

Methane (CH4), a potent greenhouse gas, contributes about one third to the global green house gas emissions. CH4-assimilating microbes (mostly methanotrophs) in upland soils play very crucial role in mitigating the CH4 release into the atmosphere. Agricultural, environmental, and climatic shifts can alter CH4 sink profiles of soils, likely through shifts in CH4-assimilating microbial community structure and function. Landuse change, as forest and grassland ecosystems altered to agro-ecosystems, has already attenuated the soil CH4 sink potential, and are expected to be continued in the future. We hypothesized that variations in CH4 uptake rates in soils under different landuse practices could be an indicative of alterations in the abundance and/or type of methanotrophic communities in such soils. However, only a few studies have addressed to number and methanotrophs diversity and their correlation with the CH4 sink potential in soils of rehabilitated/restored lands. We focus on landuse practices that can potentially mitigate CH4 gas emissions, the most prominent of which are improved cropland, grazing land management, use of bio-fertilizers, and restoration of degraded lands. In this perspective paper, it is proposed that restoration of degraded lands can contribute considerably to improved soil CH4 sink strength by retrieving/conserving abundance and assortment of efficient methanotrophic communities. We believe that this report can assist in identifying future experimental directions to the relationships between landuse changes, methane-assimilating microbial communities and soil CH4 sinks. The exploitation of microbial communities other than methanotrophs can contribute significantly to the global CH4 sink potential and can add value in mitigating the CH4 problems.

First principles study of the Ag nanoclusters adsorption effect on the photocatalytic properties of AgBr(1 1 0) surface

NASA Astrophysics Data System (ADS)

Chi, Yuhua; Zhao, Lianming; Li, Xue; Zhu, Houyu; Guo, Wenyue

2018-05-01

The electronic structures and photocatalytic performance of Agn/AgBr(1 1 0)(n = 7-13) are studied using density functional theory (DFT). The adsorption of Agn (n = 7-13) nanoclusters on AgBr(1 1 0) surface induces a new metal-induced gap band (MIGB) located between the valence band (VB) and the conduction band (CB), the variety of the electronic characters of AgBr(1 1 0) favor the visible and infrared light absorption, which improves the sunlight utilization. The dominant localization of the photo-excited electrons on the Agn clusters of Agn/AgBr(1 1 0)(n = 7-13) facilitates the oxidation-reduction reactions occurring on the surface and also effectively reduces the photolysis of AgBr under the sunlight irradiation. The overpotentials of the CB and VB edges indicate that photocatalytic conversion of CO2 with H2O to methanol is possible on AgBr(1 1 0) deposited with the Agn nanoclusters, which has been realized experimentally (An et al., 2012). The substantial strengthening of visible and infrared light absorption and the free energy profiles for the conversion of CO2 with H2O to methanol indicate that Ag13/AgBr(1 1 0) surface can be expected to be the excellent photocatalysts.

Ripening and storage conditions of Chétoui and Arbequina olives: Part I. Effect on olive oils volatiles profile.

PubMed

Hachicha Hbaieb, Rim; Kotti, Faten; Gargouri, Mohamed; Msallem, Monji; Vichi, Stefania

2016-07-15

The distinctive aroma of virgin olive oil is mainly attributed to its volatile profile including components responsible for positive attributes and others for sensory defects resulting from chemical oxidation and exogenous enzymes. For this reason, the evolution of volatile compounds from Chétoui and Arbequina virgin olive oils during olive ripening and storage (at 4 and 25 °C during 4 weeks) was investigated. The profile of volatile phenols during olive storage was also studied. Quantitative differences in the volatile compounds during olive storage at 4 and 25 °C according to olive cultivar was determined. Concerning the volatile phenols, the Arbequina olives were the most affected by high storage temperature, as the formation of these compounds, especially 4-ethyl and 4-vinyl derivatives of phenol and guaiacol were more noticeable in Arbequina oils extracted from stored fruits at 25 °C. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electromigration and morphological changes in Ag nanostructures

NASA Astrophysics Data System (ADS)

Chatterjee, A.; Bai, T.; Edler, F.; Tegenkamp, C.; Weide-Zaage, K.; Pfnür, H.

2018-02-01

Electromigration (EM) as a structuring tool was investigated in Ag nanowires (width 300 nm, thickness 25 nm) and partly in notched and bow-tie Ag structures on a Si(1 0 0) substrate in ultra-high vacuum using a four-tip scanning tunneling microscope in combination with a scanning electron microscope. From simulations of Ag nanowires we got estimates of temperature profiles, current density profiles, EM and thermal migration (TM) mass flux distributions within the nanowire induced by critical current densities of 108 A cm-2. At room temperature, the electron wind force at these current densities by far dominates over thermal diffusion, and is responsible for formation of voids at the cathode and hillocks at the anode side. For current densities that exceed the critical current densities necessary for EM, a new type of wire-like structure formation was found both at room temperature and at 100 K for notched and bow-tie structures. This suggests that the simultaneous action of EM and TM is structure forming, but with a very small influence of TM at low temperature.

A measurement system for the atmospheric trace gases CH4 and CO

NASA Technical Reports Server (NTRS)

Condon, E. P.

1977-01-01

A system for measuring ambient clean air levels of the atmospheric trace gases methane and carbon monoxide is described. The analytical method consists of a gas chromatographic technique that incorporates sample preconcentration with catalytic conversion of CO to CH4 and subsequent flame ionization detection of these gases. The system has sufficient sensitivity and repeatability to make the precise measurements required to establish concentration profiles for CO and CH4 in the planetary boundary layer. A discussion of the bottle sampling program being conducted to obtain the samples for the concentration profiles is also presented.

Facile NOx interconversion over preoxidized Ag(111)

NASA Astrophysics Data System (ADS)

Klacar, S.; Martin, N. M.; Gustafson, J.; Blomberg, S.; Liu, Z.; Axnanda, S.; Chang, R.; Lundgren, E.; Grönbeck, H.

2013-11-01

X-ray photoelectron spectroscopy and density functional theory calculations are used to investigate NO adsorption at low (100 K) and room temperature (RT) over preoxidized Ag(111). At 100 K, the data indicates presence of NO and N2O2, with little or no nitrite/nitrate formation. This is consistent with the calculated surface core level shifts and the pronounced barrier for nitrite formation. At RT, the recorded spectra indicate a complex interconversion between adsorbed species with an initial formation of a p(4 × 4) nitrate overlayer. With increasing NO pressure, the experimental results are best rationalized by partial nitrate decomposition into nitrites and subsequent NO physisorption, which leads to the formation of N2O3-like species.

Desorption of oxygen from alloyed Ag/Pt(111)

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

Jankowski, Maciej; Wormeester, Herbert, E-mail: h.wormeester@utwente.nl; Zandvliet, Harold J. W.

2014-06-21

We have investigated the interaction of oxygen with the Ag/Pt(111) surface alloy by thermal desorption spectroscopy (TDS). The surface alloy was formed during the deposition of sub-monolayer amounts of silver on Pt(111) at 800 K and subsequent cooling to 300 K. The low-temperature phase of the surface alloy is composed of nanometer-sized silver rich stripes, embedded within platinum-rich domains, which were characterized with spot profile analysis low energy electron diffraction. The TDS measurements show that oxygen adsorption is blocked on Ag sites: the saturation coverage of oxygen decreases with increasing Ag coverage. Also, the activation energy for desorption (E{sub des})more » decreases with Ag coverage. The analysis of the desorption spectra from clean Pt(111) shows a linear decay of E{sub des} with oxygen coverage, which indicates repulsive interactions between the adsorbed oxygen atoms. In contrast, adsorption on alloyed Ag/Pt(111) leads to an attractive interaction between adsorbed oxygen atoms.« less

Analysis of Ozone And CO2 Profiles Measured At A Diary Facility

NASA Astrophysics Data System (ADS)

Ogunjemiyo, S. O.; Hasson, A. S.; Ashkan, S.; Steele, J.; Shelton, T.

2015-12-01

Ozone and carbon dioxide are both greenhouse gasses in the planetary boundary layer. Ozone is a harmful secondary pollutant in the troposphere produced mostly during the day when there is a photochemical reaction in which primary pollutant precursors such as nitrous oxide (NOx) or volatile organic compounds (VOC's) mix with sunlight. As with most pollutants in the lower troposphere, both ozone and carbon dioxide vary in spatial and temporal scale depending on sources of pollution, environmental conditions and the boundary layer dynamics. Among the several factors that influence ozone variation, the seasonal changes in meteorological parameters and availability of ozone precursors are crucial because they control ozone formation and decay. Understanding how the difference in emission sources affect vertical transport of ozone and carbon dioxide is considered crucial to the improvement of their regional inventory sources. The purpose of this study is to characterize vertical transport of ozone and carbon at a diary facility. The study was conducted in the summer of 2011 and 2012 at a commercial dairy facility in Central California and involved profile measurements of ozone and CO2 using electrochemical ozonesondes, meteorological sondes and CO2 probe tethered to a 9 cubic meters helium balloon. On each day of the data collection, multiple balloon launches were made over a period representing different stages of the boundary layer development. The results show ozone and CO2 profiles display different characteristics. Regardless of the time of the day, the CO2 concentration decreases with height with a sharp gradient near the surface that is strengthened by a stable atmospheric condition, a feature suggesting the surface as the source. On the other hand, ozone profiles show greater link to the evolution of the lower boundary layer. Ozone profiles display unique features indicating ozone destruction near the surface. This unusual near the surface, observed even in the

Enhancement of Ag nanoparticles concentration by prior ion implantation

NASA Astrophysics Data System (ADS)

Mu, Xiaoyu; Wang, Jun; Liu, Changlong

2017-09-01

Thermally grown SiO2 layer on Si substrates were singly or sequentially implanted with Zn or Cu and Ag ions at the same fluence of 2 × 1016/cm2. The profiles of implanted species, structure, and spatial distribution of the formed nanoparticles (NPs) have been characterized by the cross-sectional transmission electron microscope (XTEM) and Rutherford backscattering spectrometry (RBS). It is found that pre-implantation of Zn or Cu ions could suppress the self sputtering of Ag atoms during post Ag ion implantation, which gives rise to fabrication of Ag NPs with a high density. Moreover, it has also been demonstrated that the suppressing effect strongly depends on the applied energy and mobility of pre-implanted ions. The possible mechanism for the enhanced Ag NPs concentration has been discussed in combination with SRIM simulations. Both vacancy-like defects acting as the increased nucleation sites for Ag NPs and a high diffusivity of prior implanted ions in SiO2 play key roles in enhancing the deposition of Ag implants.

MICROWAVE SPECTRA AND GEOMETRIES OF C2H_{2\\cdots AgI} and C2H_{4\\cdots AgI}

NASA Astrophysics Data System (ADS)

Stephens, Susanna L.; Tew, David Peter; Walker, Nick; Legon, Anthony

2015-06-01

A chirped-pulse Fourier transform microwave spectrometer has been used to measure the microwave spectra of both C2H_{2\\cdots AgI} and C2H_{4\\cdots AgI}. These complexes are generated via laser ablation at 532 nm of a silver surface in the presence of CF3I and either C2H_{2} or C2H_{4} and argon and are stabilized by a supersonic expansion. Rotational (A0, B0, C0) and centrifugal distortion constants (ΔJ and ΔJK) of each molecule have been determined as well the nuclear electric quadrupole coupling constants the iodine atom (χaa(I) and χbb-χcc(I)). The spectrum of each molecule is consistent with a C2v structure in which the metal atom interacts with the π-orbital of the ethene or ethyne molecule. Isotopic substitutions of atoms within the C2H_{2} or C2H_{4} subunits are in progress and in conjunction with high level ab initio calculations will allow for accurate determination of the geometry of each molecule. These to complexes are put in the context of the recently studied H2S\\cdots AgI, OC\\cdotsAgI, H3N\\cdots AgI and (CH3)_{3N\\cdots AgI}. S.Z. Riaz, S.L. Stephens, W. Mizukami, D.P. Tew, N.R. Walker, A.C. Legon, Chem. Phys. Let., 531, 1-12 (2012) S.L. Stephens, W. Mizukami, D.P. Tew, N.R. Walker, A.C. Legon, J. Chem. Phys., 136(6), 064306 (2012) D.M. Bittner, D.P. Zaleski, S.L. Stephens, N.R. Walker, A.C. Legon, Study in progress.

cChIP-seq: a robust small-scale method for investigation of histone modifications.

PubMed

Valensisi, Cristina; Liao, Jo Ling; Andrus, Colin; Battle, Stephanie L; Hawkins, R David

2015-12-21

ChIP-seq is highly utilized for mapping histone modifications that are informative about gene regulation and genome annotations. For example, applying ChIP-seq to histone modifications such as H3K4me1 has facilitated generating epigenomic maps of putative enhancers. This powerful technology, however, is limited in its application by the large number of cells required. ChIP-seq involves extensive manipulation of sample material and multiple reactions with limited quality control at each step, therefore, scaling down the number of cells required has proven challenging. Recently, several methods have been proposed to overcome this limit but most of these methods require extensive optimization to tailor the protocol to the specific antibody used or number of cells being profiled. Here we describe a robust, yet facile method, which we named carrier ChIP-seq (cChIP-seq), for use on limited cell amounts. cChIP-seq employs a DNA-free histone carrier in order to maintain the working ChIP reaction scale, removing the need to tailor reactions to specific amounts of cells or histone modifications to be assayed. We have applied our method to three different histone modifications, H3K4me3, H3K4me1 and H3K27me3 in the K562 cell line, and H3K4me1 in H1 hESCs. We successfully obtained epigenomic maps for these histone modifications starting with as few as 10,000 cells. We compared cChIP-seq data to data generated as part of the ENCODE project. ENCODE data are the reference standard in the field and have been generated starting from tens of million of cells. Our results show that cChIP-seq successfully recapitulates bulk data. Furthermore, we showed that the differences observed between small-scale ChIP-seq data and ENCODE data are largely to be due to lab-to-lab variability rather than operating on a reduced scale. Data generated using cChIP-seq are equivalent to reference epigenomic maps from three orders of magnitude more cells. Our method offers a robust and straightforward

Synthesis and immobilization of Ag(0) nanoparticles on diazonium modified electrodes: SECM and cyclic voltammetry studies of the modified interfaces.

PubMed

Noël, Jean-Marc; Zigah, Dodzi; Simonet, Jacques; Hapiot, Philippe

2010-05-18

A versatile method was used to prepare modified surfaces on which metallic silver nanoparticles are immobilized on an organic layer. The preparation method takes advantage, on one hand, of the activated reactivity of some alkyl halides with Ag-Pd alloys to produce metallic silver nanoparticles and, on the other hand, of the facile production of an anchoring polyphenyl acetate layer by the electrografting of substituted diazonium salts on carbon surfaces. Transport properties inside such modified layers were investigated by cyclic voltammetry, scanning electrochemical microscopy (SECM) in feedback mode, and conducting AFM imaging for characterizing the presence and nature of the conducting pathways. The modification of the blocking properties of the surface (or its conductivity) was found to vary to a large extent on the solvents used for surface examination (H(2)O, CH(2)Cl(2), and DMF).

Predicting kinetic nanocrystal shapes through multi-scale theory and simulation: Polyvinylpyrrolidone-mediated growth of Ag nanocrystals

NASA Astrophysics Data System (ADS)

Balankura, Tonnam; Qi, Xin; Zhou, Ya; Fichthorn, Kristen A.

2016-10-01

In the shape-controlled synthesis of colloidal Ag nanocrystals, structure-directing agents, particularly polyvinylpyrrolidone (PVP), are known to be a key additive in making nanostructures with well-defined shapes. Although many Ag nanocrystals have been successfully synthesized using PVP, the mechanism by which PVP actuates shape control remains elusive. Here, we present a multi-scale theoretical framework for kinetic Wulff shape predictions that accounts for the chemical environment, which we used to probe the kinetic influence of the adsorbed PVP film. Within this framework, we use umbrella-sampling molecular dynamics simulations to calculate the potential of mean force and diffusion coefficient profiles of Ag atom deposition onto Ag(100) and Ag(111) in ethylene glycol solution with surface-adsorbed PVP. We use these profiles to calculate the mean-first passage times and implement extensive Brownian dynamics simulations, which allows the kinetic effects to be quantitatively evaluated. Our results show that PVP films can regulate the flux of Ag atoms to be greater towards Ag(111) than Ag(100). PVP's preferential binding towards Ag(100) over Ag(111) gives PVP its flux-regulating capabilities through the lower free-energy barrier of Ag atoms to cross the lower-density PVP film on Ag(111) and enhanced Ag trapping by the extended PVP film on Ag(111). Under kinetic control, {100}-faceted nanocrystals will be formed when the Ag flux is greater towards Ag(111). The predicted kinetic Wulff shapes are in agreement with the analogous experimental system.

FunChIP: an R/Bioconductor package for functional classification of ChIP-seq shapes.

PubMed

Parodi, Alice C L; Sangalli, Laura M; Vantini, Simone; Amati, Bruno; Secchi, Piercesare; Morelli, Marco J

2017-08-15

Chromatin Immunoprecipitation followed by sequencing (ChIP-seq) generates local accumulations of sequencing reads on the genome ("peaks"), which correspond to specific protein-DNA interactions or chromatin modifications. Peaks are detected by considering their total area above a background signal, usually neglecting their shapes, which instead may convey additional biological information. We present FunChIP, an R/Bioconductor package for clustering peaks according to a functional representation of their shapes: after approximating their profiles with cubic B-splines, FunChIP minimizes their functional distance and classifies the peaks applying a k-mean alignment and clustering algorithm. The whole pipeline is user-friendly and provides visualization functions for a quick inspection of the results. An application to the transcription factor Myc in 3T9 murine fibroblasts shows that clusters of peaks with different shapes are associated with different genomic locations and different transcriptional regulatory activity. The package is implemented in R and is available under Artistic Licence 2.0 from the Bioconductor website (http://bioconductor.org/packages/FunChIP). marco.morelli@iit.it. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

In-situ spectro-microscopy on organic films: Mn-Phthalocyanine on Ag(100)

NASA Astrophysics Data System (ADS)

Al-Mahboob, Abdullah; Sadowski, Jerzy T.; Vescovo, Elio

2013-03-01

Metal phthalocyanines are attracting significant attention, owing to their potential for applications in chemical sensors, solar cells and organic magnets. As the electronic properties of molecular films are determined by their crystallinity and molecular packing, the optimization of film quality is important for improving the performance of organic devices. Here, we present the results of in situ low-energy electron microscopy / photoemission electron microscopy (LEEM/PEEM) studies of incorporation-limited growth of manganese-phthalocyanine (MnPc) on Ag(100) surfaces. MnPc thin films were grown on both, bulk Ag(100) surface and thin Ag(100)/Fe(100) films, where substrate spin-polarized electronic states can be modified through tuning the thickness of the Ag film. We also discuss the electronic structure and magnetic ordering in MnPc thin films, investigated by angle- and spin-resolved photoemission spectroscopy. Research carried out at the Center for Functional Nanomaterials and National Synchrotron Light Source, Brookhaven National Laboratory, which are supported by the U.S. Dept. of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.

New and improved CH implosions at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Hinkel, D. E.; Doeppner, T.; Kritcher, A. L.; Ralph, J. E.; Jarrott, L. C.; Albert, F.; Benedetti, L. R.; Field, J. E.; Goyon, C. S.; Hohenberger, M.; Izumi, N.; Milovich, J. L.; Bachmann, B.; Casey, D. T.; Yeamans, C. B.; Callahan, D. A.; Hurricane, O. A.

2017-10-01

Improvements to the hohlraum for CH implosions have resulted in near-record hot spot pressures, 225 Gbar. Implosion symmetry and laser energy coupling are improved by using a hohlraum that, compared to the previous high gas-fill hohlraum, is longer, larger, at lower gas fill density, and is fielded at zero wavelength separation to minimize cross-beam energy transfer. With a capsule at 90% of its original size in this hohlraum, implosion symmetry changes from oblate to prolate, at 33% cone fraction. Simulations highlight improved inner beam propagation as the cause of this symmetry change. These implosions have produced the highest yield for CH ablators at modest power and energy, i.e., 360 TW and 1.4 MJ. Upcoming experiments focus on continued improvement in shape as well as an increase in implosion velocity. Further, results and future plans on an increase in capsule size to improve margin will also be presented. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Parallel factor ChIP provides essential internal control for quantitative differential ChIP-seq.

PubMed

Guertin, Michael J; Cullen, Amy E; Markowetz, Florian; Holding, Andrew N

2018-04-17

A key challenge in quantitative ChIP combined with high-throughput sequencing (ChIP-seq) is the normalization of data in the presence of genome-wide changes in occupancy. Analysis-based normalization methods were developed for transcriptomic data and these are dependent on the underlying assumption that total transcription does not change between conditions. For genome-wide changes in transcription factor (TF) binding, these assumptions do not hold true. The challenges in normalization are confounded by experimental variability during sample preparation, processing and recovery. We present a novel normalization strategy utilizing an internal standard of unchanged peaks for reference. Our method can be readily applied to monitor genome-wide changes by ChIP-seq that are otherwise lost or misrepresented through analytical normalization. We compare our approach to normalization by total read depth and two alternative methods that utilize external experimental controls to study TF binding. We successfully resolve the key challenges in quantitative ChIP-seq analysis and demonstrate its application by monitoring the loss of Estrogen Receptor-alpha (ER) binding upon fulvestrant treatment, ER binding in response to estrodiol, ER mediated change in H4K12 acetylation and profiling ER binding in patient-derived xenographs. This is supported by an adaptable pipeline to normalize and quantify differential TF binding genome-wide and generate metrics for differential binding at individual sites.

Stratospheric N2O5, CH4, and N2O profiles from IR solar occultation spectra

NASA Technical Reports Server (NTRS)

Camy-Peyret, C.; Flaud, J.-M.; Perrin, A.; Rinsland, C. P.; Goldman, A.; Murcray, F. J.

1993-01-01

Stratospheric volume mixing ratio profiles of N2O5, CH4, and N2O have been retrieved from a set of 0.052/cm resolution (FWHM) solar occultation spectra recorded at sunrise during a balloon flight from Aire sur l'Adour, France (44 N latitude) on 12 October 1990. The N2O5 results have been derived from measurements of the integrated absorption by the 1246/cm band. Assuming a total intensity of 4.32 x 10 exp -17 cm/molecule/sq cm independent of temperature, the retrieved N2O5 volume mixing ratios in ppbv, interpolated to 2 km height spacings, are 1.64 +/- 0.49 at 37.5 km, 1.92 +/- 0.56 at 35.5 km, 2.06 +/- 0.47 at 33.5 km, 1.95 +/- 0.42 at 31.5 km, 1.60 +/- 0.33 at 29.5 km, 1.26 +/- 0.28 at 27.5 km, and 0.85 +/- 0.20 at 25.5 km. Error bars indicate the estimated 1-sigma uncertainty including the error in the total band intensity. The retrieved profiles are compared with previous measurements and photochemical model results.

Pt–Ag cubic nanocages with wall thickness less than 2 nm and their enhanced catalytic activity toward oxygen reduction

DOE PAGES

Sun, Xiaojun; Yang, Xuan; Zhang, Yun; ...

2017-09-08

We report a facile synthesis of Pt–Ag nanocages with walls thinner than 2 nm by depositing a few atomic layers of Pt as conformal shells on Ag nanocubes and then selectively removing the Ag templateviawet etching.

Pt–Ag cubic nanocages with wall thickness less than 2 nm and their enhanced catalytic activity toward oxygen reduction

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

Sun, Xiaojun; Yang, Xuan; Zhang, Yun

We report a facile synthesis of Pt–Ag nanocages with walls thinner than 2 nm by depositing a few atomic layers of Pt as conformal shells on Ag nanocubes and then selectively removing the Ag templateviawet etching.

C-H carbonylation: In situ acyl triflates ace it

NASA Astrophysics Data System (ADS)

Lee, Yong Ho; Morandi, Bill

2018-02-01

A simple palladium catalyst has mediated the facile formation of aroyl triflates -- an extremely reactive class of electrophiles. These intermediates, generated in situ, enable the Friedel-Crafts acylation of traditionally unreactive arenes, addressing a significant gap in C-H carbonylation methodology.

Simulations of laser-driven ion acceleration from a thin CH target

NASA Astrophysics Data System (ADS)

Park, Jaehong; Bulanov, Stepan; Ji, Qing; Steinke, Sven; Treffert, Franziska; Vay, Jean-Luc; Schenkel, Thomas; Esarey, Eric; Leemans, Wim; Vincenti, Henri

2017-10-01

2D and 3D computer simulations of laser driven ion acceleration from a thin CH foil using code WARP were performed. As the foil thickness varies from a few nm to μm, the simulations confirm that the acceleration mechanism transitions from the RPA (radiation pressure acceleration) to the TNSA (target normal sheath acceleration). In the TNSA regime, with the CH target thickness of 1 μ m and a pre-plasma ahead of the target, the simulations show the production of the collimated proton beam with the maximum energy of about 10 MeV. This agrees with the experimental results obtained at the BELLA laser facility (I 5 × 18 W / cm2 , λ = 800 nm). Furthermore, the maximum proton energy dependence on different setups of the initialization, i.e., different angles of the laser incidence from the target normal axis, different gradient scales and distributions of the pre-plasma, was explored. This work was supported by LDRD funding from LBNL, provided by the U.S. DOE under Contract No. DE-AC02-05CH11231, and used resources of the NERSC, a DOE office of Science User Facility supported by the U.S. DOE under Contract No. DE-AC02-05CH11231.

Space-Based Remote Imaging Spectroscopy of the Aliso Canyon CH4 Superemitter

NASA Technical Reports Server (NTRS)

Thompson, D. R.; Thorpe, A. K.; Frankenberg, C.; Green, R. O.; Duren, R.; Guanter, L.; Hollstein, A.; Middleton, E.; Ong, L.; Ungar, S.

2016-01-01

The Aliso Canyon gas storage facility near Porter Ranch, California, produced a large accidental CH4 release from October 2015 to February 2016. The Hyperion imaging spectrometer on board the EO-1 satellite successfully detected this event, achieving the first orbital attribution of CH4 to a single anthropogenic superemitter. Hyperion measured shortwave infrared signatures of CH4 near 2.3 microns at 0.01 micron spectral resolution and 30 meter spatial resolution. It detected the plume on three overpasses, mapping its magnitude and morphology. These orbital observations were consistent with measurements by airborne instruments. We evaluate Hyperion instrument performance, draw implications for future orbital instruments, and extrapolate the potential for a global survey of CH4 superemitters.

Hot Isostatic Pressing of Engineered Forms of I-AgZ

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

Jubin, Robert Thomas; Watkins, Thomas R.; Bruffey, Stephanie H.

Hot isostatic pressing (HIP) is being considered for direct conversion of 129I-bearing materials to a radiological waste form. The removal of volatile radioactive 129I from the off-gas of a nuclear fuel reprocessing facility will be necessary to comply with regulatory requirements regarding reprocessing facilities sited within the United States, and any iodine-containing media or solid sorbents generated by offgas abatement will require disposal. Zeolite minerals such as silver-exchanged mordenite (AgZ) have been studied as potential iodine sorbents and will contain 129I as chemisorbed AgI. Oak Ridge National Laboratory (ORNL) has conducted several recent studies on the HIP of both iodine-loadedmore » AgZ (I-AgZ) and other iodine-bearing zeolite minerals. The goal of these research efforts is to achieve a stable, highly leach resistant material that is reduced in volume as compared to bulk iodine-loaded I-AgZ. Through the use of HIP, it may be possible to achieve this with the addition of little or no additional materials (waste formers). Other goals for the process include that the waste form will be tolerant to high temperatures and pressures, not chemically hazardous, and that the process will result in minimal secondary waste generation. This document describes the preparation of 27 samples that are distinct from previous efforts in that they are prepared exclusively with an engineered form of AgZ that is manufactured using a binder. Iodine was incorporated solely by chemisorption. This base material is expected to be more representative of an operational system than were samples prepared previously with pure minerals.« less

BNL accelerator-based radiobiology facilities

NASA Technical Reports Server (NTRS)

Lowenstein, D. I.

2001-01-01

For the past several years, the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (USA) has provided ions of iron, silicon and gold, at energies from 600 MeV/nucleon to 10 GeV/nucleon, for the US National Aeronautics and Space Administration (NASA) radiobiology research program. NASA has recently funded the construction of a new dedicated ion facility, the Booster Applications Facility (BAF). The Booster synchrotron will supply ion beams ranging from protons to gold, in an energy range from 40-3000 MeV/nucleon with maximum beam intensities of 10(10) to 10(11) ions per pulse. The BAF Project will be described and the future AGS and BAF operation plans will be presented.

BNL accelerator-based radiobiology facilities.

PubMed

Lowenstein, D I

2001-01-01

For the past several years, the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (USA) has provided ions of iron, silicon and gold, at energies from 600 MeV/nucleon to 10 GeV/nucleon, for the US National Aeronautics and Space Administration (NASA) radiobiology research program. NASA has recently funded the construction of a new dedicated ion facility, the Booster Applications Facility (BAF). The Booster synchrotron will supply ion beams ranging from protons to gold, in an energy range from 40-3000 MeV/nucleon with maximum beam intensities of 10(10) to 10(11) ions per pulse. The BAF Project will be described and the future AGS and BAF operation plans will be presented.

CH-TRU Waste Content Codes (CH-TRUCON)

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

Washington TRU Solutions LLC

2007-08-15

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container.more » Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 of the CH-TRU Payload Appendices. For shipments to WIPP from Los Alamos National Laboratory (LANL), Nevada Test Site, and Rocky Flats Environmental Technology Site, a 20-day shipping period is applicable. Table 2B provides a summary of approved content codes and corresponding shipping categories for "Close-Proximity Shipments" (20-day shipping period). For shipments implementing the controls specified in the CH-TRAMPAC and Appendix 3.6 of the CH-TRU Payload Appendices, a 10-day shipping period is applicable. Table 2C provides a summary of approved content codes and corresponding shipping categories for "Controlled

CH-TRU Waste Content Codes (CH-TRUCON)

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

Washington TRU Solutions LLC

2007-06-15

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container.more » Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 of the CH-TRU Payload Appendices. For shipments to WIPP from Los Alamos National Laboratory (LANL), Nevada Test Site, and Rocky Flats Environmental Technology Site, a 20-day shipping period is applicable. Table 2B provides a summary of approved content codes and corresponding shipping categories for "Close-Proximity Shipments" (20-day shipping period). For shipments implementing the controls specified in the CH-TRAMPAC and Appendix 3.6 of the CH-TRU Payload Appendices, a 10-day shipping period is applicable. Table 2C provides a summary of approved content codes and corresponding shipping categories for "Controlled

CH-TRU Waste Content Codes (CH-TRUCON)

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

Washington TRU Solutions LLC

2007-09-20

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container.more » Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 of the CH-TRU Payload Appendices. For shipments to WIPP from Los Alamos National Laboratory (LANL), Nevada Test Site, and Rocky Flats Environmental Technology Site, a 20-day shipping period is applicable. Table 2B provides a summary of approved content codes and corresponding shipping categories for "Close-Proximity Shipments" (20-day shipping period). For shipments implementing the controls specified in the CH-TRAMPAC and Appendix 3.6 of the CH-TRU Payload Appendices, a 10-day shipping period is applicable. Table 2C provides a summary of approved content codes and corresponding shipping categories for "Controlled

CH-TRU Waste Content Codes (CH-TRUCON)

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

Washington TRU Solutions LLC

2006-06-20

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container.more » Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 of the CH-TRU Payload Appendices. For shipments to WIPP from Los Alamos National Laboratory (LANL), Nevada Test Site, and Rocky Flats Environmental Technology Site, a 20-day shipping period is applicable. Table 2B provides a summary of approved content codes and corresponding shipping categories for "Close-Proximity Shipments" (20-day shipping period). For shipments implementing the controls specified in the CH-TRAMPAC and Appendix 3.6 of the CH-TRU Payload Appendices, a 10-day shipping period is applicable. Table 2C provides a summary of approved content codes and corresponding shipping categories for "Controlled

CH-TRU Waste Content Codes (CH-TRUCON)

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

Washington TRU Solutions LLC

2006-01-18

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container.more » Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 of the CH-TRU Payload Appendices. For shipments to WIPP from Los Alamos National Laboratory (LANL), Nevada Test Site, and Rocky Flats Environmental Technology Site, a 20-day shipping period is applicable. Table 2B provides a summary of approved content codes and corresponding shipping categories for "Close-Proximity Shipments" (20-day shipping period). For shipments implementing the controls specified in the CH-TRAMPAC and Appendix 3.6 of the CH-TRU Payload Appendices, a 10-day shipping period is applicable. Table 2C provides a summary of approved content codes and corresponding shipping categories for "Controlled

CH-TRU Waste Content Codes (CH-TRUCON)

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

Washington TRU Solutions LLC

2006-08-15

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container.more » Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 of the CH-TRU Payload Appendices. For shipments to WIPP from Los Alamos National Laboratory (LANL), Nevada Test Site, and Rocky Flats Environmental Technology Site, a 20-day shipping period is applicable. Table 2B provides a summary of approved content codes and corresponding shipping categories for "Close-Proximity Shipments" (20-day shipping period). For shipments implementing the controls specified in the CH-TRAMPAC and Appendix 3.6 of the CH-TRU Payload Appendices, a 10-day shipping period is applicable. Table 2C provides a summary of approved content codes and corresponding shipping categories for "Controlled

CH-TRU Waste Content Codes (CH-TRUCON)

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

Washington TRU Solutions LLC

2006-12-20

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container.more » Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 of the CH-TRU Payload Appendices. For shipments to WIPP from Los Alamos National Laboratory (LANL), Nevada Test Site, and Rocky Flats Environmental Technology Site, a 20-day shipping period is applicable. Table 2B provides a summary of approved content codes and corresponding shipping categories for "Close-Proximity Shipments" (20-day shipping period). For shipments implementing the controls specified in the CH-TRAMPAC and Appendix 3.6 of the CH-TRU Payload Appendices, a 10-day shipping period is applicable. Table 2C provides a summary of approved content codes and corresponding shipping categories for "Controlled

CH-TRU Waste Content Codes (CH-TRUCON)

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

Washington TRU Solutions LLC

2007-02-15

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container.more » Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 of the CH-TRU Payload Appendices. For shipments to WIPP from Los Alamos National Laboratory (LANL), Nevada Test Site, and Rocky Flats Environmental Technology Site, a 20-day shipping period is applicable. Table 2B provides a summary of approved content codes and corresponding shipping categories for "Close-Proximity Shipments" (20-day shipping period). For shipments implementing the controls specified in the CH-TRAMPAC and Appendix 3.6 of the CH-TRU Payload Appendices, a 10-day shipping period is applicable. Table 2C provides a summary of approved content codes and corresponding shipping categories for "Controlled

CH-TRU Waste Content Codes (CH-TRUCON)

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

Washington TRU Solutions LLC

2006-09-15

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container.more » Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 of the CH-TRU Payload Appendices. For shipments to WIPP from Los Alamos National Laboratory (LANL), Nevada Test Site, and Rocky Flats Environmental Technology Site, a 20-day shipping period is applicable. Table 2B provides a summary of approved content codes and corresponding shipping categories for "Close-Proximity Shipments" (20-day shipping period). For shipments implementing the controls specified in the CH-TRAMPAC and Appendix 3.6 of the CH-TRU Payload Appendices, a 10-day shipping period is applicable. Table 2C provides a summary of approved content codes and corresponding shipping categories for "Controlled

Thermodynamic and hydrochemical controls on CH4 in a coal seam gas and overlying alluvial aquifer: new insights into CH4 origins

PubMed Central

Owen, D. Des. R.; Shouakar-Stash, O.; Morgenstern, U.; Aravena, R.

2016-01-01

Using a comprehensive data set (dissolved CH4, δ13C-CH4, δ2H-CH4, δ13C-DIC, δ37Cl, δ2H-H2O, δ18O-H2O, Na, K, Ca, Mg, HCO3, Cl, Br, SO4, NO3 and DO), in combination with a novel application of isometric log ratios, this study describes hydrochemical and thermodynamic controls on dissolved CH4 from a coal seam gas reservoir and an alluvial aquifer in the Condamine catchment, eastern Surat/north-western Clarence-Moreton basins, Australia. δ13C-CH4 data in the gas reservoir (−58‰ to −49‰) and shallow coal measures underlying the alluvium (−80‰ to −65‰) are distinct. CO2 reduction is the dominant methanogenic pathway in all aquifers, and it is controlled by SO4 concentrations and competition for reactants such as H2. At isolated, brackish sites in the shallow coal measures and alluvium, highly depleted δ2H-CH4 (<310‰) indicate acetoclastic methanogenesis where SO4 concentrations inhibit CO2 reduction. Evidence of CH4 migration from the deep gas reservoir (200–500 m) to the shallow coal measures (<200 m) or the alluvium was not observed. The study demonstrates the importance of understanding CH4 at different depth profiles within and between aquifers. Further research, including culturing studies of microbial consortia, will improve our understanding of the occurrence of CH4 within and between aquifers in these basins. PMID:27578542

Use of the Wilkinson catalyst for the ortho-C-H heteroarylation of aromatic amines: facile access to highly extended π-conjugated heteroacenes for organic semiconductors.

PubMed

Huang, Yumin; Wu, Di; Huang, Jingsheng; Guo, Qiang; Li, Juan; You, Jingsong

2014-11-03

An unprecedented catalytic system composed of the Wilkinson catalyst [Rh(PPh3)3Cl] and CF3COOH enabled the highly regioselective cross-coupling of aromatic amines with a variety of heteroarenes through dual C-H bond cleavage. This protocol provided a facile and rapid route from readily available substrates to (2-aminophenyl)heteroaryl compounds, which may be conveniently transformed into highly extended π-conjugated heteroacenes. The experimental studies and calculations showed that thianaphtheno[3,2-b]indoles have large HOMO-LUMO energy gaps and low-lying HOMO levels, and could therefore potentially be high-performance organic semiconductors. Herein we report the first use of a rhodium(I) catalyst for oxidative C-H/C-H coupling reactions. The current innovative catalyst system is much less expensive than [RhCp*Cl2]2/AgSbF6 and could open the door for the application of this approach to other types of C-H activation processes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two-Phase Eutectic Growth in Al-Cu and Al-Cu-Ag

NASA Astrophysics Data System (ADS)

Senninger, Oriane; Peters, Matthew; Voorhees, Peter W.

2018-02-01

The microstructure developed by two-phase lamellar eutectics (α ) -(θ {-Al}2{Cu}) in Al-Cu and Al-Cu-Ag alloys is analyzed. A model of two-phase eutectic growth in multicomponent alloys is used to determine the scaling law of the eutectic microstructure using the alloy thermophysical properties. The application of the model to these alloys shows that the addition of Ag to Al-Cu alloys does not significantly change the length scale of the microstructure, which is in agreement with previous experimental studies. This is explained by the combined phenomena of the decrease in interface energies with the addition of Ag and the superheating of the (α ) phase interface induced by the Ag composition profile.

METAL MEDIA FILTERS, AG-1 SECTION FI

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

Adamson, D.

One application of metal media filters is in various nuclear air cleaning processes including applications for protecting workers, the public and the environment from hazardous and radioactive particles. To support this application the development of the ASME AG-1 FI Standard on Metal Media has been under way for more than ten years. Development of the proposed section has required resolving several difficult issues associated with operating conditions (media velocity, pressure drop, etc.), qualification testing, and quality acceptance testing. Performance characteristics of metal media are dramatically different than the glass fiber media with respect to parameters like differential pressures, operating temperatures,more » media strength, etc. These differences make existing data for a glass fiber media inadequate for qualifying a metal media filter for AG-1. In the past much work has been conducted on metal media filters at facilities such as Lawrence Livermore National Laboratory (LLNL) and Savannah River National Laboratory (SRNL) to qualify the media as High Efficiency Particulate Air (HEPA) Filters. Particle retention testing has been conducted at Oak Ridge Filter Test Facility and at Air Techniques International (ATI) to prove that the metal media meets or exceeds the 99.97% particle retention required for a HEPA Filter. Even with his testing, data was lacking to complete an AG-1 FI Standard on metal media. With funding secured by Mississippi State University (MSU) from National Nuclear Security Administration (NNSA), a research test stand is being designed and fabricated at MSU's Institute for Clean Energy Technology (ICET) Facility to obtain qualification data on metal media. This in turn will support required data needed for the FI Standard. The paper will discuss in detail how the test stand at MSU will obtain the necessary data to complete the FI Standard.« less

Ch'ol nomenclature for soil classification in the ejido Oxolotán, Tacotalpa, Tabasco, México.

PubMed

Sánchez-Hernández, Rufo; Méndez-De la Cruz, Lucero; Palma-López, David J; Bautista-Zuñiga, Francisco

2018-05-30

The traditional ecological knowledge of land of the Ch'ol originary people from southeast Mexico forms part of their cultural identity; it is local and holistic and implies an integrated physical and spiritual worldview that contributes to improve their living conditions. We analyzed the nomenclature for soil classification used in the Mexican state of Tabasco by the Ch'ol farmers with the objective of contributing to the knowledge of the Maya soil classification. A map of the study area was generated from the digital database of parcels in the ejido Oxolotán in the municipality of Tacotalpa, to which a geopedological map was overlaid in order to obtain modeled topographic profiles (Zavala-Cruz et al., Ecosistemas y Recursos Agropecuarios 3:161-171, 2016). In each modeled profile, a soil profile was made and classified according to IUSS Working Group WRB (181, 2014) in order to generate a map of soil groups, which was used to survey the study area with the participation of 245 local Ch'ol farmers for establishing an ethnopedological soil classification (Ortiz et al.: 62, 1990). In addition, we organized a participatory workshop with 35 people to know details of the names of the soils and their indicators of fertility and workability, from which we selected 15 participants for field trips and description of soil profiles. The color, texture, and stoniness are attributes important in the Ch'ol nomenclature, although the names do not completely reflect the visible characteristic of the soil surface. On the other hand, the mere presence of stones is sufficient to name a land class, while according to IUSS Working Group WRB (181, 2014), a certain amount and distribution of stones in the soil profiles is necessary to be taken into consideration in the name. Perception of soil quality by local farmers considers the compaction or hardness of the cultivable soil layer, because of which black or sandy soils are perceived as better for cultivation of banana, or as secondary

A DFT-Elucidated Comparison of the Solution-Phase and SAM Electrochemical Properties of Short-Chain Mercaptoalkylferrocenes: Synthetic and Spectroscopic Aspects, and the Structure of Fc-CH2CH2-S-S-CH2CH2-Fc.

PubMed

Lewtak, Jan P; Landman, Marilé; Fernández, Israel; Swarts, Jannie C

2016-03-07

Facile synthetic procedures to synthesize a series of difficult-to-obtain mercaptoalkylferrocenes, namely, Fc(CH2)nSH, where n = 1 (1), 2 (2), 3 (3), or 4 (4) and Fc = Fe(η(5)-C5H5)(η(5)-C5H4), are reported. Dimerization of 1-4 to the corresponding disulfides 19-22 was observed in air. Dimer 20 (Z = 2) crystallized in the triclinic space group P1̅. Dimers 20-22 could be reduced back to the original Fc(CH2)nSH derivatives with LiAlH4 in refluxing tetrahydrofuran. Density functional theory (DFT) calculations showed that the highest occupied molecular orbital of 1-4 lies exclusively on the ferrocenyl group implying that the electrochemical oxidation observed at ca. -15 < Epa < 76 mV versus FcH/FcH(+) involves exclusively an Fe(II) to Fe(III) process. Further DFT calculations showed this one-electron oxidation is followed by proton loss on the thiol group to generate a radical, Fc(CH2)nS(•), with spin density mainly located on the sulfur. Rapid exothermic dimerization leads to the observed dimers, Fc(CH2)n-S-S-(CH 2)nFc. Reduction of the ferrocenium groups on the dimer occurs at potentials that still showed the ferrocenyl group ΔE = Epa,monomer - Epc,dimer ≤ 78 mV, indicating that the redox properties of the ferrocenyl group on the mercaptans are very similar to those of the dimer. (1)H NMR measurements showed that, like ferrocenyl oxidation, the resonance position of the sulfhydryl proton, SH, and others, are dependent on -(CH2)n- chain length. Self-assembled monolayers (SAMs) on gold were generated to investigate the electrochemical behavior of 1-4 in the absence of diffusion. Under these conditions, ΔE approached 0 mV for the longer chain derivatives at slow scan rates. The surface-bound ferrocenyl group of the metal-thioether, Fc(CH2)n -S-Au, is oxidized at approximately equal potentials as the equivalent CH2Cl2-dissolved ferrocenyl species 1-4. Surface coverage by the SAMs is dependent on alkyl chain length with the largest coverage obtained for 4, while

Prevalence of HBsAg, knowledge, and vaccination practice against viral hepatitis B infection among doctors and nurses in a secondary health care facility in Lagos state, South-western Nigeria.

PubMed

Abiola, Abdul-Hakeem Olatunji; Agunbiade, Adebukola Bola; Badmos, Kabir Bolarinwa; Lesi, Adenike Olufunmilayo; Lawal, Abdulrazzaq Oluwagbemiga; Alli, Quadri Olatunji

2016-01-01

Hepatitis B Virus, a highly infectious blood-borne virus poses a major threat to public health globally due to its high prevalence rate and grave consequence in causing liver cirrhosis and hepatocelullar carcinoma, the third cause of cancer death worldwide. The aim is determine the prevalence of HBsAg, knowledge, and vaccination practices against viral hepatitis B infection among doctors and nurses in a health care facility. Study design was a descriptive cross-sectional study among all the doctors and nurses in the health care facility. Data was collected using pre-tested, structured, self-administered questionnaire and blood samples were taken from respondents and tested using commercial enzyme-linked immunosorbent assay (ELIZA) test kit to determine prevalence of hepatitis B surface antigen after informed consent. Ethical approval was obtained from Health Research and Ethics Committee of the Lagos University Teaching Hospital. Responses of the respondents to the knowledge and vaccination practices against viral hepatitis B infection were scored and graded as poor (<50%), fair (50-74%) and good (≥75%). The study was carried out in January, 2014. A total of 134 out of the 143 recruited respondents participated in the study. Prevalence of HBsAg was 1.5%. Among the respondents, 56.7% had good knowledge and 94.8% reported poor practice of vaccination against viral hepatitis B infection. Mean knowledge and vaccination practices scores (%) were 72.54+7.60 and 29.44+14.37 respectively. Only 29% of the respondents did post vaccination testing for anti HBsAg. Prevalence of HBsAg was low. Knowledge of viral hepatitis B was fair, and practice of post hepatitis B vaccination testing was poor. It is therefore recommended that the state ministry of health should organise further health education programme, institute compulsory occupational hepatitis B vaccination programme and post vaccination anti-HBS testing to ensure adequate antibody level in this adult population.

Au 329–xAg x(SR) 84 Nanomolecules: Plasmonic Alloy Faradaurate-329

DOE PAGES

Kumara, Chanaka; Zuo, Xiaobing; Cullen, David A.; ...

2015-08-10

Though significant progress has been made to improve the monodispersity of larger (>10 nm) alloy metal nanoparticles, there still exists a significant variation in nanoparticle composition, ranging from ±1000s of atoms. Here in this paper, for the first time, we report the synthesis of atomically precise (±0 metal atom variation) Au 329–xAg x(SCH 2CH 2Ph) 84 alloy nanomolecules. The composition was determined using high resolution electrospray ionization mass spectrometry. In contrast to larger (>10 nm) Au–Ag nanoparticles, the surface plasmon resonance (SPR) peak does not show a major shift, but a minor ~10 nm red-shift, upon increasing silver content. Themore » intensity of the SPR peak also varies in an intriguing manner, where a dampening is observed with medium silver incorporation, and a significant sharpening is observed upon higher Ag content. The report outlines (a) an unprecedented advance in nanoparticle mass spectrometry of high mass at atomic precision; and (b) the unexpected optical behavior of Au–Ag alloys in the region where nascent SPR emerges; specifically, in this work, the SPR-like peak does not show a major ~100 nm blue-shift with Ag alloying of Au 329 nanomolecules, as shown to be common in larger nanoparticles.« less

Stratospheric N2O5, CH4, and N2O Profiles from IR Solar Occultation Spectra

NASA Technical Reports Server (NTRS)

Peyeret, C. Camy; Flaud, J.-M.; Perrin, A.; Rinsland, C. P.; Goldman, A.; Murcray, F. J.

1993-01-01

Stratospheric volume mixing ratio profiles of N2O5, CH4, and N2O have been retrieved from a set of 0.052/ cm resolution (FWHM) solar occultation spectra recorded at sunrise during a balloon flight from Aire sur I'Adour, France (44 deg N latitude) on 12 October 1990. The N2O5 results have been derived from measurements of the integrated absorption by the 1246/ cm band. Assuming a total intensity of 4.32 x 10(exp 17)cm(exp -1) molecule sq cm(exp -2) independent of temperature, the retrieved N2O5 volume mixing ratios in ppbv (parts per billion by volume, 10(exp -9)), interpolated to 2 km height spacings, are 1.64 +/- 0.49 at 37.5 km, 1.92 +/- 0.56 at 35.5 km, 2.06 +/- 0.47 at 33.5 km, 1.95 +/- 0.42 at 31.5 km, 1.60 +/- 0.33 at 29.5 km, 1.26 +/- 0.28 at 27.5 km, and 0.85 +/- 0.20 at 25.5 km. Error bars indicate the estimated I-sigma uncertainty including the error in the total band intensity (+/- 20% has been assumed). The retrieved profiles are compared with previous measurements and photochemical model results.

AgPO2F2 and Ag9(PO2F2)14: the first Ag(i) and Ag(i)/Ag(ii) difluorophosphates with complex crystal structures.

PubMed

Malinowski, Przemysław J; Kurzydłowski, Dominik; Grochala, Wojciech

2015-12-07

The reaction of AgF2 with P2O3F4 yields a mixed valence Ag(I)/Ag(II) difluorophosphate salt with AgAg(PO2F2)14 stoichiometry - the first Ag(ii)-PO2F2 system known. This highly moisture sensitive brown solid is thermally stable up to 120 °C, which points at further feasible extension of the chemistry of Ag(ii)-PO2F2 systems. The crystal structure shows a very complex bonding pattern, comprising of polymeric Ag(PO2F2)14(4-) anions and two types of Ag(I) cations. One particular Ag(II) site present in the crystal structure of Ag9(PO2F2)14 is the first known example of square pyramidal penta-coordinated Ag(ii) in an oxo-ligand environment. Ag(i)PO2F2 - the product of the thermal decomposition of Ag9(PO2F2)14 - has also been characterized by thermal analysis, IR spectroscopy and X-ray powder diffraction. It has a complicated crystal structure as well, which consists of infinite 1D [Ag(I)O4/2] chains which are linked to more complex 3D structures via OPO bridges. The PO2F2(-) anions bind to cations in both compounds as bidentate oxo-ligands. The terminal F atoms tend to point inside the van der Waals cavities in the crystal structure of both compounds. All important structural details of both title compounds were corroborated by DFT calculations.

Isotopic signatures of anthropogenic CH4 sources in Alberta, Canada

NASA Astrophysics Data System (ADS)

Lopez, M.; Sherwood, O. A.; Dlugokencky, E. J.; Kessler, R.; Giroux, L.; Worthy, D. E. J.

2017-09-01

A mobile system was used for continuous ambient measurements of stable CH4 isotopes (12CH4 and 13CH4) and ethane (C2H6). This system was used during a winter mobile campaign to investigate the CH4 isotopic signatures and the C2H6/CH4 ratios of the main anthropogenic sources of CH4 in the Canadian province of Alberta. Individual signatures were derived from δ13CH4 and C2H6 measurements in plumes arriving from identifiable single sources. Methane emissions from beef cattle feedlots (n = 2) and landfill (n = 1) had δ13CH4 signatures of -66.7 ± 2.4‰ and -55.3 ± 0.2‰, respectively. The CH4 emissions associated with the oil or gas industry had distinct δ13CH4 signatures, depending on the formation process. Emissions from oil storage tanks (n = 5) had δ13CH4 signatures ranging from -54.9 ± 2.9‰ to -60.6 ± 0.6‰ and non-detectable C2H6, characteristic of secondary microbial methanogenesis in oil-bearing reservoirs. In contrast, CH4 emissions associated with natural gas facilities (n = 8) had δ13CH4 signatures ranging from -41.7 ± 0.7‰ to -49.7 ± 0.7‰ and C2H6/CH4 molar ratios of 0.10 for raw natural gas to 0.04 for processed/refined natural gas, consistent with thermogenic origins. These isotopic signatures and C2H6/CH4 ratios have been used for source discrimination in the weekly atmospheric measurements of stable CH4 isotopes over a two-month winter period at the Lac La Biche (LLB) measurement station, located in Alberta, approximately 200 km northeast of Edmonton. The average signature of -59.5 ± 1.4‰ observed at LLB is likely associated with transport of air after passing over oil industry sources located south of the station.

Simultaneous measurement of stratospheric O3, H2O, CH4, and N2O profiles from infrared limb thermal emissions

NASA Technical Reports Server (NTRS)

Abbas, M. M.; Glenn, M. J.; Kunde, V. G.; Brasunas, J.; Conrath, B. J.; Maguire, W. C.; Herman, J. R.

1987-01-01

Thermal emission measurements of the earth's stratospheric limb were made with a cryogenically cooled high-resolution Michelson interferometer on a balloon flight launched from Palestine, TX, on Nov. 6, 1984. Infrared spectra for complete limb sequences were obtained over portions of the 700-1940/cm range with an unapodized spectral resolution of 0.03/cm for tangent heights varying from 13 to 39 km. The observed data from 1125 to 1425/cm have been analyzed for simultaneous measurement of O3, H2O, CH4, and N2O profiles. The analysis employs line-by-line and layer-by-layer radiative-transfer calculations, including curvature and refraction effects. The optimum use of geometric and spectral effects is made to obtain sharply peaked weighting functions. Contributions from stratospheric aerosol are included by measuring the light extinction within the window regions of the observed spectra. The retrieved constituent profiles are compared with measurements made with a variety of techniques by other groups. The comparison shows good agreement with the published data for all gases, indicating the capability of retrieving trace gas profiles from high-resolution thermal emission limb measurements.

Novel high-efficiency visible-light responsive Ag 4(GeO 4) photocatalyst

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

Zhu, Xianglin; Wang, Peng; Li, Mengmeng

A novel high-efficiency visible-light responsive Ag 4(GeO 4) photocatalyst was prepared by a facile hydrothermal method. The photocatalytic activity of as-prepared Ag 4(GeO 4) was evaluated by photodegradation of methylene blue (MB) dye and water splitting experiments. The photodegradation efficiency and oxygen production efficiency of Ag 4(GeO 4) were detected to be 2.9 and 1.9 times higher than those of Ag 2O. UVvis diffuse reflectance spectroscopy (DRS), photoluminescence experiment and photoelectric effect experiments prove that the good light response and high carrier separation efficiency facilitated by the internal electric field are the main reasons for Ag 4(GeO 4)'s excellent catalyticmore » activity. Radical-trapping experiments reveal that the photogenerated holes are the main active species. Lastly, first-principles theoretical calculations provide more insight into understanding the photocatalytic mechanism of the Ag 4(GeO 4) catalyst.« less

Novel high-efficiency visible-light responsive Ag 4(GeO 4) photocatalyst

DOE PAGES

Zhu, Xianglin; Wang, Peng; Li, Mengmeng; ...

2017-04-25

A novel high-efficiency visible-light responsive Ag 4(GeO 4) photocatalyst was prepared by a facile hydrothermal method. The photocatalytic activity of as-prepared Ag 4(GeO 4) was evaluated by photodegradation of methylene blue (MB) dye and water splitting experiments. The photodegradation efficiency and oxygen production efficiency of Ag 4(GeO 4) were detected to be 2.9 and 1.9 times higher than those of Ag 2O. UVvis diffuse reflectance spectroscopy (DRS), photoluminescence experiment and photoelectric effect experiments prove that the good light response and high carrier separation efficiency facilitated by the internal electric field are the main reasons for Ag 4(GeO 4)'s excellent catalyticmore » activity. Radical-trapping experiments reveal that the photogenerated holes are the main active species. Lastly, first-principles theoretical calculations provide more insight into understanding the photocatalytic mechanism of the Ag 4(GeO 4) catalyst.« less

Kinetics of OH- and Cl-initiated oxidation of CH2dbnd CHC(O)O(CH2)2CH3 and CH2dbnd CHCH2C(O)O(CH2)2CH3 and fate of the alkoxy radicals formed

NASA Astrophysics Data System (ADS)

Rivela, Cynthia; Blanco, María B.; Teruel, Mariano A.

2016-05-01

Rate coefficients of the reactions of OH and Cl radicals with vinyl and allyl butyrate were determined for the first time at 298 K and 1 atm using the relative method to be (in cm3 molecule-1 s-1): k1(OH + CH2dbnd CHC(O)O(CH2)2CH3) = (2.61 ± 0.31) × 10-11, k2(Cl + CH2dbnd CHC(O)O(CH2)2CH3) = (2.48 ± 0.89) × 10-10, k3(OH + CH2dbnd CHCH2C(O)O(CH2)2CH3) = (2.89 ± 0.31) × 10-11, and k4(Cl + CH2dbnd CHCH2C(O)O(CH2)2CH3) = (2.25 ± 0.96) × 10-10. Reactivity trends and atmospheric lifetimes of esters are presented. Additionally, a product study shown butyric acid and polifunctional products for the reactions of vinyl and allyl butyrate, respectively and general mechanism is proposed.

Global mapping of binding sites for Nrf2 identifies novel targets in cell survival response through ChIP-Seq profiling and network analysis

PubMed Central

Malhotra, Deepti; Portales-Casamar, Elodie; Singh, Anju; Srivastava, Siddhartha; Arenillas, David; Happel, Christine; Shyr, Casper; Wakabayashi, Nobunao; Kensler, Thomas W.; Wasserman, Wyeth W.; Biswal, Shyam

2010-01-01

The Nrf2 (nuclear factor E2 p45-related factor 2) transcription factor responds to diverse oxidative and electrophilic environmental stresses by circumventing repression by Keap1, translocating to the nucleus, and activating cytoprotective genes. Nrf2 responses provide protection against chemical carcinogenesis, chronic inflammation, neurodegeneration, emphysema, asthma and sepsis in murine models. Nrf2 regulates the expression of a plethora of genes that detoxify oxidants and electrophiles and repair or remove damaged macromolecules, such as through proteasomal processing. However, many direct targets of Nrf2 remain undefined. Here, mouse embryonic fibroblasts (MEF) with either constitutive nuclear accumulation (Keap1−/−) or depletion (Nrf2−/−) of Nrf2 were utilized to perform chromatin-immunoprecipitation with parallel sequencing (ChIP-Seq) and global transcription profiling. This unique Nrf2 ChIP-Seq dataset is highly enriched for Nrf2-binding motifs. Integrating ChIP-Seq and microarray analyses, we identified 645 basal and 654 inducible direct targets of Nrf2, with 244 genes at the intersection. Modulated pathways in stress response and cell proliferation distinguish the inducible and basal programs. Results were confirmed in an in vivo stress model of cigarette smoke-exposed mice. This study reveals global circuitry of the Nrf2 stress response emphasizing Nrf2 as a central node in cell survival response. PMID:20460467

Electroactive Au@Ag nanoparticles driven electrochemical sensor for endogenous H2S detection.

PubMed

Zhao, Yuan; Yang, Yaxin; Cui, Linyan; Zheng, Fangjie; Song, Qijun

2018-05-26

In this work, a novel and facile electrochemical sensor is reported for the highly selective and sensitive detection of dissolved hydrogen sulfide (H 2 S), attributing to the redox reaction between Au@Ag core-shell nanoparticles (Au@Ag NPs) and H 2 S. Electroactive Au@Ag NPs not only possess excellent conductivity, but exhibit great electrochemical reactivity at 0.26 V due to the electrochemical oxidation from Ag° to Ag + . In the presence of H 2 S, the Ag shell of Au@Ag NPs can be oxidized to Ag 2 S, resulting in the decrease of differential pulse voltammetry (DPV) peak at 0.26 V. The electrochemical sensor exhibits a wide linear response range from 0.1 nM to 500 nM. The limit of detection (LOD) for H 2 S is as low as 0.04 nM. The developed sensor shows significant prospects in the study of pathological processes related to the mechanism of H 2 S production. Copyright © 2018. Published by Elsevier B.V.

Perspective on the reactions between F- and CH3CH2F: the free energy landscape of the E2 and SN2 reaction channels.

PubMed

Ensing, Bernd; Klein, Michael L

2005-05-10

Recently, we computed the 3D free energy surface of the base-induced elimination reaction between F(-) and CH(3)CH(2)F by using a powerful technique within Car-Parrinello molecular dynamics simulation. Here, the set of three order parameters is expanded to six, which allows the study of the competing elimination and substitution reactions simultaneously. The power of the method is exemplified by the exploration of the six-dimensional free energy landscape, sampling, and mapping out the eight stable states as well as the connecting bottlenecks. The free energy profile and barrier along the E2 and S(N)2 reaction channels are refined by using umbrella sampling. The two mechanisms do not share a common "E2C-like" transition state. Comparison with the zero temperature profiles shows a particularly significant entropy contribution to the S(N)2 channel.

Perspective on the reactions between F– and CH3CH2F: The free energy landscape of the E2 and SN2 reaction channels

PubMed Central

Ensing, Bernd; Klein, Michael L.

2005-01-01

Recently, we computed the 3D free energy surface of the base-induced elimination reaction between F– and CH3CH2F by using a powerful technique within Car–Parrinello molecular dynamics simulation. Here, the set of three order parameters is expanded to six, which allows the study of the competing elimination and substitution reactions simultaneously. The power of the method is exemplified by the exploration of the six-dimensional free energy landscape, sampling, and mapping out the eight stable states as well as the connecting bottlenecks. The free energy profile and barrier along the E2 and SN2 reaction channels are refined by using umbrella sampling. The two mechanisms do not share a common “E2C-like” transition state. Comparison with the zero temperature profiles shows a particularly significant entropy contribution to the SN2 channel. PMID:15863622

Preparation of core-shell Ag@CeO2 nanocomposite by LSPR photothermal induced interface reaction

NASA Astrophysics Data System (ADS)

Zhong, H. X.; Wei, Y.; Yue, Y. Z.; Zhang, L. H.; Liu, Y.

2016-04-01

The core-shell structure of Ag@CeO2 was prepared by a novel and facile method, which was based on the photothermal effect of localized surface plasmon resonance (LSPR). Nanoparticles (NPs) of Ag were dispersed in a solution containing citric acid, ethylene glycol and cerium nitrate, then under irradiation, Ag NPs generated heat from LSPR and the heat-induced polymerization reaction in the interface between Ag and the sol resulted in cerium gel formation only on the surface of the Ag NPs. After calcination, Ag@CeO2 was successfully obtained, then Ag@CeO2/SiO2 was prepared by loading Ag@CeO2 on SiO2. The resultant catalyst exhibited favorable activity and stability for CO oxidation. The preparation method proposed here should be extendable to other composites with metallic cores and oxide shells in which the metallic nanoparticle possesses LSPR properties.

High Resolution CH4 Emissions and Dissolved CH4 Measurements Elucidate Surface Gas Exchange Processes in Toolik Lake, Arctic Alaska

NASA Astrophysics Data System (ADS)

Del Sontro, T.; Sollberger, S.; Kling, G. W.; Shaver, G. R.; Eugster, W.

2013-12-01

Approximately 14% of the Alaskan North Slope is covered in lakes of various sizes and depths. Diffusive carbon emissions (CH4 and CO2) from these lakes offset the tundra sink by ~20 %, but the offset would substantially increase if ebullitive CH4 emissions were also considered. Ultimately, arctic lake CH4 emissions are not insignificant in the global CH4 budget and their contribution is bound to increase due to impacts from climate change. Here we present high resolution CH4 emission data as measured via eddy covariance and a Los Gatos gas analyzer during the ice free period from Toolik Lake, a deep (20 m) Arctic lake located on the Alaskan North Slope, over the last few summers. Emissions are relatively low (< 25 mg CH4 m-2 d-1) with little variation over the summer. Diurnal variations regularly occur, however, with up to 3 times higher fluxes at night. Gas exchange is a relatively difficult process to estimate, but is normally done so as the product of the CH4 gradient across the air-water interface and the gas transfer velocity, k. Typically, k is determined based on the turbulence on the water side of the interface, which is most commonly approximated by wind speed; however, it has become increasingly apparent that this assumption does not remain valid across all water bodies. Dissolved CH4 profiles in Toolik revealed a subsurface peak in CH4 at the thermocline of up to 3 times as much CH4 as in the surface water. We hypothesize that convective mixing at night due to cooling surface waters brings the subsurface CH4 to the surface and causes the higher night fluxes. In addition to high resolution flux emission estimates, we also acquired high resolution data for dissolved CH4 in surface waters of Toolik Lake during the last two summers using a CH4 equilibrator system connected to a Los Gatos gas analyzer. Thus, having both the flux and the CH4 gradient across the air-water interface measured directly, we can calculate k and investigate the processes influencing

Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum) rind extract

NASA Astrophysics Data System (ADS)

Yang, Hui; Ren, Yan-yu; Wang, Tao; Wang, Chuang

Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV-Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism.

Univariate and multivariate molecular spectral analyses of lipid related molecular structural components in relation to nutrient profile in feed and food mixtures

NASA Astrophysics Data System (ADS)

Abeysekara, Saman; Damiran, Daalkhaijav; Yu, Peiqiang

2013-02-01

The objectives of this study were (i) to determine lipid related molecular structures components (functional groups) in feed combination of cereal grain (barley, Hordeum vulgare) and wheat (Triticum aestivum) based dried distillers grain solubles (wheat DDGSs) from bioethanol processing at five different combination ratios using univariate and multivariate molecular spectral analyses with infrared Fourier transform molecular spectroscopy, and (ii) to correlate lipid-related molecular-functional structure spectral profile to nutrient profiles. The spectral intensity of (i) CH3 asymmetric, CH2 asymmetric, CH3 symmetric and CH2 symmetric groups, (ii) unsaturation (Cdbnd C) group, and (iii) carbonyl ester (Cdbnd O) group were determined. Spectral differences of functional groups were detected by hierarchical cluster analysis (HCA) and principal components analysis (PCA). The results showed that the combination treatments significantly inflicted modifications (P < 0.05) in nutrient profile and lipid related molecular spectral intensity (CH2 asymmetric stretching peak height, CH2 symmetric stretching peak height, ratio of CH2 to CH3 symmetric stretching peak intensity, and carbonyl peak area). Ratio of CH2 to CH3 symmetric stretching peak intensity, and carbonyl peak significantly correlated with nutrient profiles. Both PCA and HCA differentiated lipid-related spectrum. In conclusion, the changes of lipid molecular structure spectral profiles through feed combination could be detected using molecular spectroscopy. These changes were associated with nutrient profiles and functionality.

Preparation of AgInS2 nanoparticles by a facile microwave heating technique; study of effective parameters, optical and photovoltaic characteristics

NASA Astrophysics Data System (ADS)

Tadjarodi, Azadeh; Cheshmekhavar, Amir Hossein; Imani, Mina

2012-12-01

In this work, AgInS2 (AIS) semiconductor nanoparticles were synthesized by an efficient and facile microwave heating technique using several sulfur sources and solvents in the different reaction times. The SEM images presented the particle morphology for all of the obtained products in the arranged reaction conditions. The particle size of 70 nm was obtained using thioacetamide (TAA), ethylene glycol (EG) as the sulfur source and solvent, respectively at the reaction time of 5 min. It was found that the change of the mentioned parameters lead to alter on the particle size of the resulting products. The average particle size was estimated using a microstructure measurement program and Minitab statistical software. The optical band gap energy of 1.96 eV for the synthesized AIS nanoparticles was determined by the diffuse reflectance spectroscopy (DRS). AgInS2/CdS/CuInSe2 heterojunction solar cell was constructed and photovoltaic parameters, i.e., open-circuit voltage (Voc), short-circuit current (Jsc) and fill factor (FF) were estimated by photocurrent-voltage (I-V) curve. The calculated fill factor of 30% and energy conversion efficiency of 1.58% revealed the capability of AIS nanoparticles to use in the solar cell devices.

Unimolecular reactivity of organotrifluoroborate anions, RBF3- , and their alkali metal cluster ions, M(RBF3 )2- (M = Na, K; R = CH3 , CH3 CH2 , CH3 (CH2 )3 , CH3 (CH2 )5 , c-C3 H5 , C6 H5 , C6 H5 CH2 , CH2 CHCH2 , CH2 CH, C6 H5 CO).

PubMed

Bathie, Fiona L B; Bowen, Chris J; Hutton, Craig A; O'Hair, Richard A J

2018-07-15

Potassium organotrifluoroborates (RBF 3 K) are important reagents used in organic synthesis. Although mass spectrometry is commonly used to confirm their molecular formulae, the gas-phase fragmentation reactions of organotrifluoroborates and their alkali metal cluster ions have not been previously reported. Negative-ion mode electrospray ionization (ESI) together with collision-induced dissociation (CID) using a triple quadrupole mass spectrometer were used to examine the fragmentation pathways for RBF 3 - (where R = CH 3 , CH 3 CH 2 , CH 3 (CH 2 ) 3 , CH 3 (CH 2 ) 5 , c-C 3 H 5 , C 6 H 5 , C 6 H 5 CH 2 , CH 2 CHCH 2 , CH 2 CH, C 6 H 5 CO) and M(RBF 3 ) 2 - (M = Na, K), while density functional theory (DFT) calculations at the M06/def2-TZVP level were used to examine the structures and energies associated with fragmentation reactions for R = Me and Ph. Upon CID, preferentially elimination of HF occurs for RBF 3 - ions for systems where R = an alkyl anion, whereas R - formation is favoured when R = a stabilized anion. At higher collision energies loss of F - and additional HF losses are sometimes observed. Upon CID of M(RBF 3 ) 2 - , formation of RBF 3 - is the preferred pathway with some fluoride transfer observed only when M = Na. The DFT-calculated relative thermochemistry for competing fragmentation pathways is consistent with the experiments. The main fragmentation pathways of RBF 3 - are HF elimination and/or R - loss. This contrasts with the fragmentation reactions of other organometallate anions, where reductive elimination, beta hydride transfer and bond homolysis are often observed. The presence of fluoride transfer upon CID of Na(RBF 3 ) 2 - but not K(RBF 3 ) 2 - is in agreement with the known fluoride affinities of Na + and K + and can be rationalized by Pearson's HSAB theory. Copyright © 2018 John Wiley & Sons, Ltd.

ChIPBase v2.0: decoding transcriptional regulatory networks of non-coding RNAs and protein-coding genes from ChIP-seq data.

PubMed

Zhou, Ke-Ren; Liu, Shun; Sun, Wen-Ju; Zheng, Ling-Ling; Zhou, Hui; Yang, Jian-Hua; Qu, Liang-Hu

2017-01-04

The abnormal transcriptional regulation of non-coding RNAs (ncRNAs) and protein-coding genes (PCGs) is contributed to various biological processes and linked with human diseases, but the underlying mechanisms remain elusive. In this study, we developed ChIPBase v2.0 (http://rna.sysu.edu.cn/chipbase/) to explore the transcriptional regulatory networks of ncRNAs and PCGs. ChIPBase v2.0 has been expanded with ∼10 200 curated ChIP-seq datasets, which represent about 20 times expansion when comparing to the previous released version. We identified thousands of binding motif matrices and their binding sites from ChIP-seq data of DNA-binding proteins and predicted millions of transcriptional regulatory relationships between transcription factors (TFs) and genes. We constructed 'Regulator' module to predict hundreds of TFs and histone modifications that were involved in or affected transcription of ncRNAs and PCGs. Moreover, we built a web-based tool, Co-Expression, to explore the co-expression patterns between DNA-binding proteins and various types of genes by integrating the gene expression profiles of ∼10 000 tumor samples and ∼9100 normal tissues and cell lines. ChIPBase also provides a ChIP-Function tool and a genome browser to predict functions of diverse genes and visualize various ChIP-seq data. This study will greatly expand our understanding of the transcriptional regulations of ncRNAs and PCGs. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Simulation study of 3-5 keV x-ray conversion efficiency from Ar K-shell vs. Ag L-shell targets on the National Ignition Facility laser

NASA Astrophysics Data System (ADS)

Kemp, G. E.; Colvin, J. D.; Fournier, K. B.; May, M. J.; Barrios, M. A.; Patel, M. V.; Scott, H. A.; Marinak, M. M.

2015-05-01

Tailored, high-flux, multi-keV x-ray sources are desirable for studying x-ray interactions with matter for various civilian, space and military applications. For this study, we focus on designing an efficient laser-driven non-local thermodynamic equilibrium 3-5 keV x-ray source from photon-energy-matched Ar K-shell and Ag L-shell targets at sub-critical densities (˜nc/10) to ensure supersonic, volumetric laser heating with minimal losses to kinetic energy, thermal x rays and laser-plasma instabilities. Using Hydra, a multi-dimensional, arbitrary Lagrangian-Eulerian, radiation-hydrodynamics code, we performed a parameter study by varying initial target density and laser parameters for each material using conditions readily achievable on the National Ignition Facility (NIF) laser. We employ a model, benchmarked against Kr data collected on the NIF, that uses flux-limited Lee-More thermal conductivity and multi-group implicit Monte-Carlo photonics with non-local thermodynamic equilibrium, detailed super-configuration accounting opacities from Cretin, an atomic-kinetics code. While the highest power laser configurations produced the largest x-ray yields, we report that the peak simulated laser to 3-5 keV x-ray conversion efficiencies of 17.7% and 36.4% for Ar and Ag, respectively, occurred at lower powers between ˜100-150 TW. For identical initial target densities and laser illumination, the Ag L-shell is observed to have ≳10× higher emissivity per ion per deposited laser energy than the Ar K-shell. Although such low-density Ag targets have not yet been demonstrated, simulations of targets fabricated using atomic layer deposition of Ag on silica aerogels (˜20% by atomic fraction) suggest similar performance to atomically pure metal foams and that either fabrication technique may be worth pursuing for an efficient 3-5 keV x-ray source on NIF.

ChIP-seq.

PubMed

Kim, Tae Hoon; Dekker, Job

2018-05-01

Owing to its digital nature, ChIP-seq has become the standard method for genome-wide ChIP analysis. Using next-generation sequencing platforms (notably the Illumina Genome Analyzer), millions of short sequence reads can be obtained. The densities of recovered ChIP sequence reads along the genome are used to determine the binding sites of the protein. Although a relatively small amount of ChIP DNA is required for ChIP-seq, the current sequencing platforms still require amplification of the ChIP DNA by ligation-mediated PCR (LM-PCR). This protocol, which involves linker ligation followed by size selection, is the standard ChIP-seq protocol using an Illumina Genome Analyzer. The size-selected ChIP DNA is amplified by LM-PCR and size-selected for the second time. The purified ChIP DNA is then loaded into the Genome Analyzer. The ChIP DNA can also be processed in parallel for ChIP-chip results. © 2018 Cold Spring Harbor Laboratory Press.

ChIP and ChIP-Related Techniques: Expanding the Fields of Application and Improving ChIP Performance.

PubMed

Visa, Neus; Jordán-Pla, Antonio

2018-01-01

Protein-DNA interactions in vivo can be detected and quantified by chromatin immunoprecipitation (ChIP). ChIP has been instrumental for the advancement of epigenetics and has set the groundwork for the development of a number of ChIP-related techniques that have provided valuable information about the organization and function of genomes. Here, we provide an introduction to ChIP and discuss the applications of ChIP in different research areas. We also review some of the strategies that have been devised to improve ChIP performance.

Sensory and Volatile Profiles of Monovarietal North Tunisian Extra Virgin Olive Oils from 'Chétoui' Cultivar.

PubMed

Essid, Faten; Sifi, Samira; Beltrán, Gabriel; Sánchez, Sebastián; Raïes, Aly

2016-07-01

The quality of olive oil is defined as a combination of characteristics that significantly determine its acceptance by consumers. This study was carried out to compare sensorial and chemical characteristics of sixty 'Chétoui' extra virgin olive oils (EVOOc) samples from six northern areas in Tunisia (Tebourba (EVOOT); Other regions (EVOON): Mornag, Sidi Amor, El Kef, Béjà and Jendouba). Trained panel taste detected ten sensory attributes. EVOOT and EVOON were defined by 'tomato' and 'grass/ leave notes, respectively. Twenty one volatile compounds from EVOOc were extracted and identified by Headspace Solid-Phase Microextraction followed by Gas Chromatography- Flame Ionization Detector. Principal component and cluster analysis of all studied parameters showed that EVOOT differed from EVOON. Sensory and volatile profiles of EVOOc revealed that the perception of different aromas, in monovarietal olive oil, was the result of synergic effect of oils' various components, whose composition was influenced by the geographical growing area.

Structure evolution of self-catalyzed grown Au, Ag and their alloy nanostructure

NASA Astrophysics Data System (ADS)

Zhu, Zhu; Chen, Feng; Xu, Chunxiang; Yang, Guangcan; Zhu, Ye; Luo, Zhaoxu

2017-12-01

Monitoring the nucleation and growth of nanomaterials is a key technique for material synthesis design and control. An efficient fabrication method can be realized deeply understanding the growth mechanisms. Here, noble metal nanostructures, gold (Au) nanoparticles, silver nanostructures (Ag nanoparticles/Ag nanowires) and gold-silver alloy nanoparticles were prepared in a facile method at room temperature. The growth processes of the Au nanoparticles, Ag nanowires and Au-Ag alloy nanoparticles can be monitored real-timely through the ultraviolet visible absorption (UV-vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM). It is found that the whole formation involved Digestive ripening and Ostwald ripening cooperative mechanism. Furthermore, the self-assembly growth is noticed in the oriented attachment of precursor Ag monomers into nanowires under the same synthetic conditions without external templates or rigorous conditions. This result can provide a platform to discover the underlying growth mechanism of wet-chemistry methods for metal nanostructure fabrication.

Tuning the SERS Response with Ag-Au Nanoparticle-Embedded Polymer Thin Film Substrates.

PubMed

Rao, V Kesava; Radhakrishnan, T P

2015-06-17

Development of facile routes to the fabrication of thin film substrates with tunable surface enhanced Raman scattering (SERS) efficiency and identification of the optimal conditions for maximizing the enhancement factor (EF) are significant in terms of both fundamental and application aspects of SERS. In the present work, polymer thin films with embedded bimetallic nanoparticles of Ag-Au are fabricated by a simple two-stage protocol. Ag nanoparticles are formed in the first stage, by the in situ reduction of silver nitrate by the poly(vinyl alcohol) (PVA) film through mild thermal annealing, without any additional reducing agent. In the second stage, aqueous solutions of chloroauric acid spread on the Ag-PVA thin film under ambient conditions, lead to the galvanic displacement of Ag by Au in situ inside the film, and the formation of Ag-Au particles. Evolution of the morphology of the bimetallic nanoparticles into hollow cage structures and the distribution of Au on the nanoparticles are revealed through electron microscopy and energy dispersive X-ray spectroscopy. The localized surface plasmon resonance (LSPR) extinction of the nanocomposite thin film evolves with the Ag-Au composition; theoretical simulation of the extinction spectra provides insight into the observed trends. The Ag-Au-PVA thin films are found to be efficient substrates for SERS. The EF follows the variation of the LSPR extinction vis-à-vis the excitation laser wavelength, but with an offset, and the maximum SERS effect is obtained at very low Au content; experiments with Rhodamine 6G showed EFs on the order of 10(8) and a limit of detection of 0.6 pmol. The present study describes a facile and simple fabrication of a nanocomposite thin film that can be conveniently deployed in SERS investigations, and the utility of the bimetallic system to tune and maximize the EF.

SiO2-Ag-SiO2 core/shell structure with a high density of Ag nanoparticles for CO oxidation catalysis.

PubMed

Feng, Xiaoqian; Li, Hongmo; Zhang, Qing; Zhang, Peng; Song, Xuefeng; Liu, Jing; Zhao, Liping; Gao, Lian

2016-11-11

SiO 2 -Ag-SiO 2 , a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsulated between a shallow SiO 2 surface layer and a SiO 2 submicrosphere substrate (∼200 nm), has been synthesized from [Formula: see text] and SiO 2 spheres by a facile one-pot hydrothermal method. The composite is proposed to result from the dynamic balance between the [Formula: see text] reduction and the dissolution-redeposition of SiO 2 in mild basic media. The synthetic mechanism and the roles of the reaction time, temperature, and the amount of ammonia in the formation of this unique structure are investigated and discussed. The composite structure shows superior catalytic performance in CO oxidation to the control Ag/SiO 2 structure prepared by impregnation. Pre-treatment by O 2 at 600 °C significantly improves the catalytic performance of the composite structure and preserves the nanocomposite structure well.

Hydroxylation of Benzene via C-H Activation Using Bimetallic CuAg@g-C3N4

EPA Science Inventory

A photoactive bimetallic CuAg@g-C3N4 catalyst system has been designed and synthesized by impregnating copper and silver nanoparticles over the graphitic carbon nitride surface. Its application has been demonstrated in the hydroxylation of benzene under visible light.

ChIPpeakAnno: a Bioconductor package to annotate ChIP-seq and ChIP-chip data

PubMed Central

2010-01-01

Background Chromatin immunoprecipitation (ChIP) followed by high-throughput sequencing (ChIP-seq) or ChIP followed by genome tiling array analysis (ChIP-chip) have become standard technologies for genome-wide identification of DNA-binding protein target sites. A number of algorithms have been developed in parallel that allow identification of binding sites from ChIP-seq or ChIP-chip datasets and subsequent visualization in the University of California Santa Cruz (UCSC) Genome Browser as custom annotation tracks. However, summarizing these tracks can be a daunting task, particularly if there are a large number of binding sites or the binding sites are distributed widely across the genome. Results We have developed ChIPpeakAnno as a Bioconductor package within the statistical programming environment R to facilitate batch annotation of enriched peaks identified from ChIP-seq, ChIP-chip, cap analysis of gene expression (CAGE) or any experiments resulting in a large number of enriched genomic regions. The binding sites annotated with ChIPpeakAnno can be viewed easily as a table, a pie chart or plotted in histogram form, i.e., the distribution of distances to the nearest genes for each set of peaks. In addition, we have implemented functionalities for determining the significance of overlap between replicates or binding sites among transcription factors within a complex, and for drawing Venn diagrams to visualize the extent of the overlap between replicates. Furthermore, the package includes functionalities to retrieve sequences flanking putative binding sites for PCR amplification, cloning, or motif discovery, and to identify Gene Ontology (GO) terms associated with adjacent genes. Conclusions ChIPpeakAnno enables batch annotation of the binding sites identified from ChIP-seq, ChIP-chip, CAGE or any technology that results in a large number of enriched genomic regions within the statistical programming environment R. Allowing users to pass their own annotation data such

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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

As-synthesis of nanostructure AgCl/Ag/MCM-41 composite

NASA Astrophysics Data System (ADS)

Sohrabnezhad, Sh.; Pourahmad, A.

2012-02-01

In this work, we present the simple synthetic route for silver chloride/silver nanoparticles (AgCl/Ag-NPs) using as-synthesis method. The structure, composition and optical properties of such material were investigated by transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray diffraction (XRD) and FTIR. Powder X-ray diffraction showed that when AgNO 3 content is below 0.1 wt.% in synthetic gel, the guest AgCl/Ag-NPs is formed on the silica channel wall, and lower exists in the crystalline state. When AgNO 3 content exceeds this value, AgCl/Ag nanoparticles can be observed in high crystalline state. The absorption at 327 nm ascribed to the characteristic absorption of the AgCl semiconductor. Ag nanoparticles have been shown to exist in the nanocomposite at 375 nm. When AgNO 3 content is above 0.1 wt.% in synthetic gel, spectra exhibited stronger absorption at 450-700 nm that was attributed to the surface plasmonic resonance of silver nanoparticles. The obtained AgCl/Ag/MCM-41 sample exhibit enhanced photocatalytic activity for the degradation of methylene blue under visible-light irradiation.

Photoelectric characteristics of CH3NH3PbI3/p-Si heterojunction

NASA Astrophysics Data System (ADS)

Yamei, Wu; Ruixia, Yang; Hanmin, Tian; Shuai, Chen

2016-05-01

Organic-inorganic hybrid perovskite CH3NH3PbI3 film is prepared on p-type silicon substrate using the one-step solution method to form a CH3NH3PbI3/p-Si heterojunction. The film morphology and structure are characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The photoelectric properties of the CH3NH3PbI3/p-Si heterojunction are studied by testing the current-voltage (I-V) with and without illumination and capacitance-voltage (C-V) characteristics. It turns out from the I-V curve without illumination that the CH3NH3PbI3/p-Si heterojunction has a rectifier feature with the rectification ratio over 70 at the bias of ±5 V. Also, there appears a photoelectric conversion phenomenon on this heterojunction with a short circuit current (Isc) of 0.16 μA and an open circuit voltage (Voc) of about 10 mV The high frequency C-V characteristic of the Ag/CH3NH3PbI3/p-Si heterojunction turns out to be similar to that of the metal-insulator-semiconductor (MIS) structure, and a parallel translation of the C-V curve along the forward voltage axis is found. This parallel translation means the existence of defects at the CH3NH3PbI3/p-Si interface and positive fixed charges in the CH3NH3PbI3 layer. The defects at the interface of the CH3NH3PbI3/p-Si heterojunction result in the dramatic decline of the Voc. Besides, the C-V test of CH3NH3PbI3 film shows a non-linear dielectric property and the dielectric value is about 4.64 as calculated. Project supported by the Hebei Province Natural Science Foundation of China (No. F2014202184) and the Tianjin Natural Science Foundation of China (No. 15JCZDJC37800).

Selenium carboxylic acids betaine; 3,3‧,3″-selenotris(propanoic acid) betaine, Se(CH2CH2COOH)2(CH2CH2COO)

NASA Astrophysics Data System (ADS)

Doudin, Khalid; Törnroos, Karl W.

2017-06-01

Attempts to prepare [Se(CH2CH2COOH)3]+Cl- from Se(CH2CH2COOH)2 and H2Cdbnd CHCOOH in concentrated hydrochloric acid, for the corresponding sulfonium salt, led exclusively to the Se-betaine, Se(CH2CH2COOH)2(CH2CH2COO). The Se-betaine crystallises in the space group P2l/c with the cell dimensions at 223 K, a = 5.5717(1), b = 24.6358(4), c = 8.4361(1) Å, β = 104.762(1)°, V = 1119.74(3) Å3, Z = 4, Dcalc = 1.763 Mgm- 3, μ = 3.364 Mm-1. The structure refined to RI = 0.0223 for 2801 reflections with Fo > 4σ(Fo). In the crystalline state the molecule is intermolecularly linked to neighbouring molecules by a number of hydrogen bonds; a very strong carboxylic-carboxylate bond with an O⋯O distance of 2.4435(16) Å, a medium strong carboxylic-carboxylate bond with an O⋯O distance of 2.6431(16) Å and several weak O⋯H(CH2) with O⋯C distances between 3.2 and 3.3 Å. In the carboxylic group involved in the very strong hydrogen bond the O⋯H bond is antiperiplanar to the Cdbnd O bond while the Osbnd H bond is periplanar to the Cdbnd O bond in the second carboxylic group. Based upon the Csbnd O bond lengths and the elongation of the Osbnd H bond involved in the strong hydrogen bond one may describe the compound as strongly linked units of Se(CH2CH2COOH)(CH2CH2COO)2 rather than Se(CH2CH2COOH)2(CH2CH2COO). The selenium atom forms two strong intramolecular 1,5-Se⋯O contacts, with a carboxylate oxygen atom, 2.9385(12) Å, and with a carboxylic oxygen atom, 2.8979(11) Å. To allow for these contacts the two organic fragments have been forced into the periplanar conformation. The molecule is only slightly asymmetric with regard to the Csbnd Sesbnd C bond angles but is very asymmetric with regard to the torsion angles.

Synthesis and crystallographic characterization of a mononuclear cobalt(III) complex possessing both thiol­ate and thio­ether donors: reactivity of an thiol­ate-bridged penta­nuclear Co2Ag3 complex with iodo­methane

PubMed Central

Fukuda, Yosuke; Yoshinari, Nobuto; Konno, Takumi

2017-01-01

Treatment of an S-bridged penta­nuclear AgI 3CoIII 2 complex, [Ag3{Co(L)}2]3+ [L 3– = N(CH2NHCH2CH2S−)3], in which two tris­(thiol­ate)-type mononuclear CoIII units ([Co(L)]) are bridged by three AgI ions through S atoms, with iodo­methane (CH3I) gave a new CoIII mononuclear complex, [Co(LMe2)]2+ [LMe2 − = N(CH2NHCH2CH2S−)(CH2NHCH2CH2SCH3)2], systematic name: {2-[(bis{[2-(methylsulfanyl)ethyl]aminomethyl}aminomethyl)amino]ethanethiolato}cobalt(III) bis(hexafluoridophosphate). This cationic complex was crystallized with PF6 − anions to form the title compound, [Co(LMe2)](PF6)2. In the [Co(LMe2)]2+ cation, two of three thiol­ate groups in [Co(L)] are methyl­ated while one thiol­ate group remains unreacted. Although a total of eight stereoisomers are possible for [Co(LMe2)]2+, only a pair of enanti­omers {ΛRR- and ΔSS-[Co(LMe2)]2+} are selectively formed. In the crystal, the complex cations and the PF­6 − anions are connected through weak N—H⋯F, C—H⋯F and C—H⋯S hydrogen bonds into a three-dimensional structure. Two F atoms in one PF6 anion are disordered over two sets of sites with refined occupancies of 0.61 (4) and 0.39 (4) and two F atoms in the other PF6 − anion are disordered over two sets of sites with occupancies of 0.5. PMID:28529774

Thermochemical properties of silver tellurides including empressite (AgTe) and phase diagrams for Ag-Te and Ag-Te-O

NASA Astrophysics Data System (ADS)

Voronin, Mikhail V.; Osadchii, Evgeniy G.; Brichkina, Ekaterina A.

2017-10-01

This study compiles original experimental and literature data on the thermodynamic properties (ΔfG°, S°, ΔfH°) of silver tellurides (α-Ag2Te, β-Ag2Te, Ag1.9Te, Ag5Te3, AgTe) obtained by the method of solid-state galvanic cell with the RbAg4I5 and AgI solid electrolytes. The thermodynamic data for empressite (AgTe, pure fraction from Empress Josephine Mine, Colorado USA) have been obtained for the first time by the electrochemical experiment with the virtual reaction Ag + Te = AgTe. The Ag-Te phase diagrams in the T - x and log fTe2 (gas) - 1/ T coordinates have been refined, and the ternary Ag-Te-O diagrams with Ag-Te-TeO2 (paratellurite) composition range have been calculated.

Univariate and multivariate molecular spectral analyses of lipid related molecular structural components in relation to nutrient profile in feed and food mixtures.

PubMed

Abeysekara, Saman; Damiran, Daalkhaijav; Yu, Peiqiang

2013-02-01

The objectives of this study were (i) to determine lipid related molecular structures components (functional groups) in feed combination of cereal grain (barley, Hordeum vulgare) and wheat (Triticum aestivum) based dried distillers grain solubles (wheat DDGSs) from bioethanol processing at five different combination ratios using univariate and multivariate molecular spectral analyses with infrared Fourier transform molecular spectroscopy, and (ii) to correlate lipid-related molecular-functional structure spectral profile to nutrient profiles. The spectral intensity of (i) CH(3) asymmetric, CH(2) asymmetric, CH(3) symmetric and CH(2) symmetric groups, (ii) unsaturation (CC) group, and (iii) carbonyl ester (CO) group were determined. Spectral differences of functional groups were detected by hierarchical cluster analysis (HCA) and principal components analysis (PCA). The results showed that the combination treatments significantly inflicted modifications (P<0.05) in nutrient profile and lipid related molecular spectral intensity (CH(2) asymmetric stretching peak height, CH(2) symmetric stretching peak height, ratio of CH(2) to CH(3) symmetric stretching peak intensity, and carbonyl peak area). Ratio of CH(2) to CH(3) symmetric stretching peak intensity, and carbonyl peak significantly correlated with nutrient profiles. Both PCA and HCA differentiated lipid-related spectrum. In conclusion, the changes of lipid molecular structure spectral profiles through feed combination could be detected using molecular spectroscopy. These changes were associated with nutrient profiles and functionality. Copyright © 2012 Elsevier B.V. All rights reserved.

Biopolymer mediated nanoparticles synthesized from Adenia hondala for enhanced tamoxifen drug delivery in breast cancer cell line

NASA Astrophysics Data System (ADS)

Varadharajaperumal, Pradeepa; Subramanian, Balakumar; Santhanam, Amutha

2017-09-01

Silver nanoparticles (AgNPs) are an important class of nanomaterials, which have used as antimicrobial and disinfectant agents due to their detrimental effect on target cells. In the present study it was explored to deliver a novel tamoxifen drug system that can be used in breast cancer treatment, based on chitosan coated silver nanoparticles on MCF-7 human breast cancer cells. AgNPs synthesized from Adenia hondala tuber extract were used to make the chitosan coated AgNPs (Ch-AgNPs), in which the drug tamoxifen was loaded on chitosan coated silver nanoparticles (Tam-Ch-AgNPs) to construct drug loaded nanoparticles as drug delivery system. The morphology and characteristics of the Ch-AgNPs were investigated by UV, FTIR, zeta potential and FESEM. Furthermore, the toxicity of AgNPs, Ch-AgNPs, Tam-Ch-AgNPs was evaluated through cell viability, lactate dehydrogenase leakage, reactive oxygen species generation, caspase-3, DNA laddering, and TUNEL assay in human breast cancer cells (MCF-7) and HBL-100 continuous cell line as a control. Treatment of cancer cells with various concentrations of AgNPs, Ch-AgNPs, Tam-Ch-AgNPs for 24 h revealed that Tam-Ch-AgNPs could inhibit cell viability and induce significant membrane leakage in a dose-dependent manner. Cells exposed to Tam-Ch-AgNPs showed increased reactive oxygen species and hydroxyl radical production when compared to AgNPs, Ch-AgNPs. Furthermore, the apoptotic effects of AgNPs, Ch-AgNPs, Tam-Ch-AgNPs were confirmed by activation of caspase-3 and DNA nuclear fragmentation. The present findings suggest that Tam-Ch-AgNPs could contribute to the development of a suitable anticancer drug delivery.

Profile of hepatitis B and C virus infection in prisoners in Lubuk Pakam correctional facilities

NASA Astrophysics Data System (ADS)

Rey, I.; Saragih, R. H.; Effendi-YS, R.; Sembiring, J.; Siregar, G. A.; Zain, L. H.

2018-03-01

Prisoners in correctional facilities are predisposed to chronic viral infections because of their high-risk behaviors or unsafe lifestyle. The economic and public health burden of chronic hepatitis B and C and its sequelae need to be addressed, such as by finding the risk factors and therefore reducing the spread of HCV and HBV infection in prisons. This study aimed to see the profile of Hepatitis B and C Virus Infection in prisoners in Lubuk Pakam Correctional Facilities. This cross-sectional study was in Lubuk Pakam Correctional Facilities in 2016. From 1114 prisoners in Lubuk Pakam correctional facility, we randomly examined 120 prisoners for HBV and HCV serology markers. From 120 prisoners, six prisoners were HBV positive, 21 prisoners were HCV positive and one prisoner positive for both HCV and HBV infection. The most common risk factors for prisoners getting HBV infection are tattoos and free sex (36.4% and 36.4%, respectively). The most common risk factors for HCV infection in prisoners are tattoos and free sex (40% and 35%, respectively).

Journey of the ALK-inhibitor CH5424802 to phase II clinical trial.

PubMed

Latif, Muhammad; Saeed, Aamer; Kim, Seong Hwan

2013-09-01

The anaplastic lymphoma kinase (ALK) receptor tyrosine kinase represents a potential therapeutic target. Specially, a variety of alterations in the ALK gene including mutations, overexpression, amplification, translocations and structural rearrangements, are involved in human cancer tumorigenesis. The second-generation ALK inhibitor CH5424802 (development code: AF802; Chugai Pharmaceutical, a subsidiary of Roche) achieves tumor regression with excellent tolerance and shows promising efficacy in patients with ALK-positive non-small cell lung cancer. CH5424802 shows good kinase selectivity, has a promising pharmacokinetics profile, and has strong antiproliferative activity in several ALK-driven tumor models. CH5424802 has also shown anti-tumor activity in mouse xenograft studies. Here, we summarize recent advances and the evidence that CH5424802 acts as an ALK inhibitor. We also discuss its potential for further development as an anticancer drug in clinical trials.

Promotional effects of chemisorbed oxygen and hydroxide in the activation of C-H and O-H bonds over transition metal surfaces

NASA Astrophysics Data System (ADS)

Hibbitts, David; Neurock, Matthew

2016-08-01

Electronegative coadsorbates such as atomic oxygen (O*) and hydroxide (OH*) can act as Brønsted bases when bound to Group 11 as well as particular Group 8-10 metal surfaces and aid in the activation of X-H bonds. First-principle density functional theory calculations were carried out to systematically explore the reactivity of the C-H bonds of methane and surface methyl intermediates as well as the O-H bond of methanol directly and with the assistance of coadsorbed O* and OH* intermediates over Group 11 (Cu, Ag, and Au) and Group 8-10 transition metal (Ru, Rh, Pd, Os, Ir, and Pt) surfaces. C-H as well as O-H bond activation over the metal proceeds via a classic oxidative addition type mechanism involving the insertion of the metal center into the C-H or O-H bond. O* and OH* assist C-H and O-H activation over particular Group 11 and Group 8-10 metal surfaces via a σ-bond metathesis type mechanism involving the oxidative addition of the C-H or O-H bond to the metal along with a reductive deprotonation of the acidic C-H and O-H bond over the M-O* or M-OH* site pair. The O*- and OH*-assisted C-H activation paths are energetically preferred over the direct metal catalyzed C-H scission for all Group 11 metals (Cu, Ag, and Au) with barriers that are 0.4-1.5 eV lower than those for the unassisted routes. The barriers for O*- and OH*-assisted C-H activation of CH4 on the Group 8-10 transition metals, however, are higher than those over the bare transition metal surfaces by as much as 1.4 eV. The C-H activation of adsorbed methyl species show very similar trends to those for CH4 despite the differences in structure between the weakly bound methane and the covalently adsorbed methyl intermediates. The activation of the O-H bond of methanol is significantly promoted by O* as well as OH* intermediates over both the Group 11 metals (Cu, Ag, and Au) as well as on all Group 8-10 metals studied (Ru, Rh, Pd, Os, Ir, and Pt). The O*- and OH*-assisted CH3O-H barriers are 0.6 to 2

Even-electron [M-H](+) ions generated by loss of AgH from argentinated peptides with N-terminal imine groups.

PubMed

Plaviak, Alexandra; Osburn, Sandra; Patterson, Khiry; van Stipdonk, Michael J

2016-01-15

Experiments were performed to probe the creation of apparent even-electron, [M-H](+) ions by CID of Ag-cationized peptides with N-terminal imine groups (Schiff bases). Imine-modified peptides were prepared using condensation reactions with aldehydes. Ag(+) -cationized precursors were generated by electrospray ionization (ESI). Tandem mass spectrometry (MS(n) ) and collision-induced dissociation (CID) were performed using a linear ion trap mass spectrometer. Loss of AgH from peptide [M + Ag](+) ions, at the MS/MS stage, creates closed-shell [M-H](+) ions from imine-modified peptides. Isotope labeling unambiguously identifies the imine C-H group as the source of H eliminated in AgH. Subsequent CID of the [M-H](+) ions generated sequence ions that are analogous to those produced from [M + H](+) ions of the imine-modified peptides. Experiments show (a) formation of novel even-electron peptide cations by CID and (b) the extent to which sequence ions (conventional b, a and y ions) are generated from peptides with fixed charge site and thus lacking a conventional mobile proton. Copyright © 2015 John Wiley & Sons, Ltd.

Laboratory Spectroscopy of CH(+) and Isotopic CH

NASA Technical Reports Server (NTRS)

Pearson, John C.; Drouin, Brian J.

2006-01-01

The A1II - X1(Epsilon) electronic band of the CH(+) ion has been used as a probe of the physical and dynamical conditions of the ISM for 65 years. In spite of being one of the first molecular species observed in the ISM and the very large number of subsequent observations with large derived column densities, the pure rotational spectra of CH+ has remained elusive in both the laboratory and in the ISM as well. We report the first laboratory measurement of the pure rotation of the CH(+) ion and discuss the detection of CH-13(+) in the ISM. Also reported are the somewhat unexpected chemical conditions that resulted in laboratory production.

libChEBI: an API for accessing the ChEBI database.

PubMed

Swainston, Neil; Hastings, Janna; Dekker, Adriano; Muthukrishnan, Venkatesh; May, John; Steinbeck, Christoph; Mendes, Pedro

2016-01-01

ChEBI is a database and ontology of chemical entities of biological interest. It is widely used as a source of identifiers to facilitate unambiguous reference to chemical entities within biological models, databases, ontologies and literature. ChEBI contains a wealth of chemical data, covering over 46,500 distinct chemical entities, and related data such as chemical formula, charge, molecular mass, structure, synonyms and links to external databases. Furthermore, ChEBI is an ontology, and thus provides meaningful links between chemical entities. Unlike many other resources, ChEBI is fully human-curated, providing a reliable, non-redundant collection of chemical entities and related data. While ChEBI is supported by a web service for programmatic access and a number of download files, it does not have an API library to facilitate the use of ChEBI and its data in cheminformatics software. To provide this missing functionality, libChEBI, a comprehensive API library for accessing ChEBI data, is introduced. libChEBI is available in Java, Python and MATLAB versions from http://github.com/libChEBI, and provides full programmatic access to all data held within the ChEBI database through a simple and documented API. libChEBI is reliant upon the (automated) download and regular update of flat files that are held locally. As such, libChEBI can be embedded in both on- and off-line software applications. libChEBI allows better support of ChEBI and its data in the development of new cheminformatics software. Covering three key programming languages, it allows for the entirety of the ChEBI database to be accessed easily and quickly through a simple API. All code is open access and freely available.

Surface-enhanced Raman scattering of a Ag/oligo(phenyleneethynylene)/Ag sandwich.

PubMed

Fletcher, Melissa; Alexson, D M; Prokes, Sharka; Glembocki, Orest; Vivoni, Alberto; Hosten, Charles

2011-02-01

α,ω-Dithiols are a useful class of compounds in molecular electronics because of their ability to easily adsorb to two metal surfaces, producing a molecular junction. We have prepared Ag nanosphere/oligo(phenyleneethynylene)/Ag sol (AgNS/OPE/Ag sol) and Ag nanowire/oligo(phenyleneethynylene)/Ag sol (AgNW/OPE/Ag sol) sandwiches to simulate the architecture of a molecular electronic device. This was achieved by self-assembly of OPE on the silver nanosurface, deprotection of the terminal sulfur, and deposition of Ag sol atop the monolayer. These sandwiches were then characterized by surface-enhanced Raman scattering (SERS) spectroscopy. The resulting spectra were compared to the bulk spectrum of the dimer and to the Ag nanosurface/OPE SERS spectra. The intensities of the SERS spectra in both systems exhibit a strong dependence on Ag deposition time and the results are also suggestive of intense interparticle coupling of the electromagnetic fields in both the AgNW/OPE/Ag and the AgNS/OPE/Ag systems. Three previously unobserved bands (1219, 1234, 2037 cm(-1)) arose in the SER spectra of the sandwiches and their presence is attributed to the strong enhancement of the electromagnetic field which is predicted from the COSMOL computational package. The 544 cm(-1) disulfide bond which is observed in the spectrum of solid OPE but is absent in the AgNS/OPE/Ag and AgNW/OPE/Ag spectra is indicative of chemisorption of OPE to the nanoparticles through oxidative dissociation of the disulfide bond. Copyright © 2010 Elsevier B.V. All rights reserved.

Cationic and Neutral Cp*M(NO)(κ2-Ph2PCH2CH2PPh2) Complexes of Molybdenum and Tungsten: Lewis-Acid-Induced Intramolecular C-H Activation.

PubMed

Handford, Rex C; Wakeham, Russell J; Patrick, Brian O; Legzdins, Peter

2017-03-20

Treatment of CH 2 Cl 2 solutions of Cp*M(NO)Cl 2 (Cp* = η 5 -C 5 (CH 3 ) 5 ; M = Mo, W) first with 2 equiv of AgSbF 6 in the presence of PhCN and then with 1 equiv of Ph 2 PCH 2 CH 2 PPh 2 affords the yellow-orange salts [Cp*M(NO)(PhCN)(κ 2 -Ph 2 PCH 2 CH 2 PPh 2 )](SbF 6 ) 2 in good yields (M = Mo, W). Reduction of [Cp*M(NO)(PhCN)(κ 2 -Ph 2 PCH 2 CH 2 PPh 2 )](SbF 6 ) 2 with 2 equiv of Cp 2 Co in C 6 H 6 at 80 °C produces the corresponding 18e neutral compounds, Cp*M(NO)(κ 2 -Ph 2 PCH 2 CH 2 PPh 2 ) which have been isolated as analytically pure orange-red solids. The addition of 1 equiv of the Lewis acid, Sc(OTf) 3 , to solutions of Cp*M(NO)(κ 2 -Ph 2 PCH 2 CH 2 PPh 2 ) at room temperature results in the immediate formation of thermally stable Cp*M(NO→Sc(OTf) 3 )(H)(κ 3 -(C 6 H 4 )PhPCH 2 CH 2 PPh 2 ) complexes in which one of the phenyl substituents of the Ph 2 PCH 2 CH 2 PPh 2 ligands has undergone intramolecular orthometalation. In a similar manner, addition of BF 3 produces the analogous Cp*M(NO→BF 3 )(H)(κ 3 -(C 6 H 4 )PhPCH 2 CH 2 PPh 2 ) complexes. In contrast, B(C 6 F 5 ) 3 forms the 1:1 Lewis acid-base adducts, Cp*M(NO→B(C 6 F 5 ) 3 )(κ 2 -Ph 2 PCH 2 CH 2 PPh 2 ) in CH 2 Cl 2 at room temperature. Upon warming to 80 °C, Cp*Mo(NO→B(C 6 F 5 ) 3 )(κ 2 -Ph 2 PCH 2 CH 2 PPh 2 ) converts cleanly to the orthometalated product Cp*Mo(NO→B(C 6 F 5 ) 3 )(H)(κ 3 -(C 6 H 4 )PhPCH 2 CH 2 PPh 2 ), but Cp*W(NO→B(C 6 F 5 ) 3 )(κ 2 -Ph 2 PCH 2 CH 2 PPh 2 ) generates a mixture of products whose identities remain to be ascertained. Attempts to extend this chemistry to include related Ph 2 PCH 2 PPh 2 compounds have had only limited success. All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses.

Intramolecular vibrational redistribution of CH 2I 2 dissolved in supercritical Xe

NASA Astrophysics Data System (ADS)

Sekiguchi, K.; Shimojima, A.; Kajimoto, O.

2003-03-01

Intramolecular vibrational energy redistribution (IVR) of CH 2I 2 in supercritical Xe has been studied. The first overtone of the C-H stretching mode was excited with a near infrared laser pulse and the transient UV absorption near 390 nm was monitored. Signals showed a rise and decay profile, which gave the IVR and VET (intermolecular vibrational energy transfer) rates, respectively. Solvent density dependence of each rate was obtained by tuning the pressure at a constant temperature. The IVR rate in supercritical Xe increased with increasing solvent density and asymptotically reached a limiting value. This result suggests that the IVR process of CH 2I 2 in condensed phase is a solvent-assisted process.

Welded-Ag-nanowires/FTO conducting film with high transmittance and its application in transparent supercapacitors

NASA Astrophysics Data System (ADS)

Qiao, Zhensong; Yang, Xiaopeng; Liu, Feng; Duan, Guangbin; Cao, Bingqiang

2017-03-01

Silver nanowires (AgNW) with a small diameter were synthesized by a facile and novel polyol reduction method. Ag nanowires ink was then spun on the surface of F-doped SnO2 (FTO) to form the AgNW/FTO conducting film. Welding treatment of the AgNW/FTO conducting film not only increased the optical transmittance from 71.9 % to 79.3 % at 550 nm and decreased the sheet resistance from 11.4 ohm sq-1 to 9.8 ohm sq-1, but also improved the adhesivity of AgNW network on FTO substrate. Furthermore, MnO2 nanosheets were directly deposited on welded-AgNW/FTO (wAF) substrate to prepare a transparent MnO2/weled-AgNW/FTO (MwAF) composite electrode. The MwAF electrode displayed excellent electrochemical performance, including high specific capacitance (375 F g-1 at 5 mV s-1) and superior cycle stability (173.3 % of the initial capacitance after 20000 GCD cycles).

Interdiffusion and stress development in single-crystalline Pd/Ag bilayers

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

Noah, Martin A., E-mail: m.noah@is.mpg.de; Flötotto, David; Wang, Zumin

Interdiffusion and stress evolution in single-crystalline Pd/single-crystalline Ag thin films were investigated by Auger electron spectroscopy sputter-depth profiling and in-situ X-ray diffraction, respectively. The concentration-dependent chemical diffusion coefficient, as well as the impurity diffusion coefficient of Ag in Pd could be determined in the low temperature range of 356 °C–455 °C. As a consequence of the similarity of the strong concentration-dependences of the intrinsic diffusion coefficients, the chemical diffusion coefficient varies only over three orders of magnitude over the whole composition range, despite the large difference of six orders of magnitude of the self-diffusion coefficients of Ag in Ag and Pd inmore » Pd. It is shown that the Darken-Manning treatment should be adopted for interpretation of the experimental data; the Nernst-Planck treatment yielded physically unreasonable results. Apart from the development of compressive thermal stress, the development of stress in both sublayers separately could be ascribed to compositional stress (tensile in the Ag sublayer and compressive in the Pd sublayer) and dominant relaxation processes, especially in the Ag sublayer. The effect of these internal stresses on the values determined for the diffusion coefficients is shown to be negligible.« less

Clinical, biochemical, virological and sonographic profile of incidentally detected asymptomatic HBsAg positive subjects, in Bangladesh.

PubMed

Ishaque, S M; Mahmuduzzaman, M; Rahman, M A; Uddoula, M S; Rahman, M Z; Khan, M R; Chowdhury, M S

2014-01-01

Chronic hepatitis B virus (HBV) is known to be the significant cause of Liver related morbidity and mortality, affecting 400 million people worldwide and a major public health problem in Bangladesh where carrier rates of HBV infection varies from 7.5 to 10%. In Bangladesh prevalence of asymptomatic HBV infection and incidentally detected HBsAg positive subjects were not well studied. The aim of this study is to evaluate the disease activity, replicative status of the virus and to find out the stages of chronic liver disease among incidentally detected asymptomatic HBsAg positive Bangladeshi subjects. Two hundred (200) incidentally detected healthy HBsAg positive subject were evaluated clinically, biochemically, serologically and ultrasonographically from January 2004 to June 2008. HBeAg was found positive in 17(8.5%), anti-HBe was positive in 174(87%), raised serum ALT (>45iu/L) in 45(22.5%), prothrombine time (PT) >3 sec of control in 33(16.5%). Ultrasonography showed coarse hepatic echotexture in 13(6.5%). Evidence of active viral replication and signs of chronic liver disease were observed among incidentally detected healthy HBsAg positive subjects. Such individuals should be followed up at regular interval to evaluate the replicative status of the virus and disease activity so that appropriate measures could be initiated in time.

Effect of carbon ion irradiation on Ag diffusion in SiC

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

Leng, Bin; Ko, Hyunseok; Gerczak, Tyler J.

Transport of Ag fission product through the silicon-carbide (SiC) diffusion barrier layer in TRISO fuel particles is of considerable interest given the application of this fuel type in high temperature gas-cooled reactor (HTGR) and other future reactor concepts. The reactor experiments indicate that radiation may play an important role in release of Ag; however so far the isolated effect of radiation on Ag diffusion has not been investigated in controlled laboratory experiments. In this study, we investigate the diffusion couples of Ag and polycrystalline 3C–SiC, as well as Ag and single crystalline 4H–SiC samples before and after irradiation with Cmore » 2+ ions. The diffusion couple samples were exposed to temperatures of 1500 °C, 1535 °C, and 1569 °C, and the ensuing diffusion profiles were analyzed by secondary ion mass spectrometry (SIMS). We found that diffusion coefficients calculated from these measurements indicate that Ag diffusion was greatly enhanced by carbon irradiation due to a combined effect of radiation damage on diffusion and the presence of grain boundaries in polycrystalline SiC samples.« less

Effect of carbon ion irradiation on Ag diffusion in SiC

DOE PAGES

Leng, Bin; Ko, Hyunseok; Gerczak, Tyler J.; ...

2015-11-14

Transport of Ag fission product through the silicon-carbide (SiC) diffusion barrier layer in TRISO fuel particles is of considerable interest given the application of this fuel type in high temperature gas-cooled reactor (HTGR) and other future reactor concepts. The reactor experiments indicate that radiation may play an important role in release of Ag; however so far the isolated effect of radiation on Ag diffusion has not been investigated in controlled laboratory experiments. In this study, we investigate the diffusion couples of Ag and polycrystalline 3C–SiC, as well as Ag and single crystalline 4H–SiC samples before and after irradiation with Cmore » 2+ ions. The diffusion couple samples were exposed to temperatures of 1500 °C, 1535 °C, and 1569 °C, and the ensuing diffusion profiles were analyzed by secondary ion mass spectrometry (SIMS). We found that diffusion coefficients calculated from these measurements indicate that Ag diffusion was greatly enhanced by carbon irradiation due to a combined effect of radiation damage on diffusion and the presence of grain boundaries in polycrystalline SiC samples.« less

Graphene-supported Ag-based core-shell nanoparticles for hydrogen generation in hydrolysis of ammonia borane and methylamine borane.

PubMed

Yang, Lan; Luo, Wei; Cheng, Gongzhen

2013-08-28

Well-dispersed magnetically recyclable core-shell Ag@M (M = Co, Ni, Fe) nanoparticles (NPs) supported on graphene have been synthesized via a facile in situ one-step procedure, using methylamine borane (MeAB) as a reducing agent under ambient condition. Their catalytic activity toward hydrolysis of ammonia borane (AB) were studied. Although the Ag@Fe/graphene NPs are almost inactive, the as-prepared Ag@Co/graphene NPs are the most reactive catalysts, followed by Ag@Ni/graphene NPs. Compared with AB and NaBH4, the as-synthesized Ag@Co/graphene catalysts which reduced by MeAB exert the highest catalytic activity. Additionally, the Ag@Co NPs supported on graphene exhibit higher catalytic activity than the catalysts with other conventional supports, such as the SiO2, carbon black, and γ-Al2O3. The as-synthesized Ag@Co/graphene NPs exert satisfied catalytic activity, with the turnover frequency (TOF) value of 102.4 (mol H2 min(-1) (mol Ag)(-1)), and the activation energy Ea value of 20.03 kJ/mol. Furthermore, the as-synthesized Ag@Co/graphene NPs show good recyclability and magnetically reusability for the hydrolytic dehydrogenation of AB and MeAB, which make the practical reusing application of the catalysts more convenient. Moreover, this simple synthetic method indicates that MeAB could be used as not only a potential hydrogen storage material but also an efficient reducing agent. It can be easily extended to facile preparation of other graphene supported metal NPs.

Impact of artifact removal on ChIP quality metrics in ChIP-seq and ChIP-exo data

PubMed Central

Carroll, Thomas S.; Liang, Ziwei; Salama, Rafik; Stark, Rory; de Santiago, Ines

2014-01-01

With the advent of ChIP-seq multiplexing technologies and the subsequent increase in ChIP-seq throughput, the development of working standards for the quality assessment of ChIP-seq studies has received significant attention. The ENCODE consortium's large scale analysis of transcription factor binding and epigenetic marks as well as concordant work on ChIP-seq by other laboratories has established a new generation of ChIP-seq quality control measures. The use of these metrics alongside common processing steps has however not been evaluated. In this study, we investigate the effects of blacklisting and removal of duplicated reads on established metrics of ChIP-seq quality and show that the interpretation of these metrics is highly dependent on the ChIP-seq preprocessing steps applied. Further to this we perform the first investigation of the use of these metrics for ChIP-exo data and make recommendations for the adaptation of the NSC statistic to allow for the assessment of ChIP-exo efficiency. PMID:24782889

The ChArMEx database

NASA Astrophysics Data System (ADS)

Ferré, Hélène; Descloitres, Jacques; Fleury, Laurence; Boichard, Jean-Luc; Brissebrat, Guillaume; Focsa, Loredana; Henriot, Nicolas; Mastrorillo, Laurence; Mière, Arnaud; Vermeulen, Anne

2013-04-01

(SEVIRI, TRIMM, PARASOL...) stored in the ICARE data archive using OpeNDAP protocole The website will soon propose new facilities. In particular, many in situ datasets will be homogenized and inserted in a relational database, in order to enable more accurate data selection and download of different datasets in a shared format. In order to meet the operational needs of the airborne and ground based observational teams during the ChArMEx 2012 pre-campaign and the 2013 experiment, a day-to-day quick look and report display website has been developed too: http://choc.sedoo.org. It offers a convenient way to browse weather conditions and chemical composition during the campaign periods.

Sonochemical synthesis of Ag nanoclusters: electrogenerated chemiluminescence determination of dopamine.

PubMed

Liu, Tao; Zhang, Lichun; Song, Hongjie; Wang, Zhonghui; Lv, Yi

2013-01-01

We report a facile one-pot sonochemical approach to preparing highly water-soluble Ag nanoclusters (NCs) using bovine serum albumin as a stabilizing agent and reducing agent in aqueous solution. Intensive electrogenerated chemiluminescence (ECL) was observed from the as-prepared Ag (NCs) and successfully applied for the ECL detection of dopamine with high sensitivity and a wide detection range. A possible ECL mechanism is proposed for the preparation of Ag NCs. With this method, the dopamine concentration was determined in the range of 8.3 × 10(-9) to 8.3 × 10(-7) mol/L without the obvious interference of uric acid, ascorbic acid and some other neurotransmitters, such as serotonin, epinephrine and norepinephrine, and the detection limit was 9.2 × 10(-10) mol/L at a signal/noise ratio of 3. Copyright © 2013 John Wiley & Sons, Ltd.

Electrically conductive nanostructured silver doped zinc oxide (Ag:ZnO) prepared by solution-immersion technique

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

Afaah, A. N., E-mail: afaahabdullah@yahoo.com; Asib, N. A. M., E-mail: amierahasib@yahoo.com; Aadila, A., E-mail: aadilaazizali@gmail.com

2016-07-06

p-type ZnO films have been fabricated on ZnO-seeded glass substrate, using AgNO{sub 3} as a source of silver dopant by facile solution-immersion. Cleaned glass substrate were seeded with ZnO by mist-atomisation, and next the seeded substrates were immersed in Ag:ZnO solution. The effects of Ag doping concentration on the Ag-doped ZnO have been investigated. The substrates were immersed in different concentrations of Ag dopant with variation of 0, 1, 3, 5 and 7 at. %. The surface morphology of the films was characterized by field emission scanning electron microscope (FESEM). In order to investigate the electrical properties, the films weremore » characterized by Current-Voltage (I-V) measurement. FESEM micrographs showed uniform distribution of nanostructured ZnO and Ag:ZnO. Besides, the electrical properties of Ag-doped ZnO were also dependent on the doping concentration. The I-V measurement result indicated the electrical properties of 1 at. % Ag:ZnO thin film owned highest electrical conductivity.« less

Optogenetic Stimulation of Arcuate Nucleus Kiss1 Neurons Reveals a Steroid-Dependent Glutamatergic Input to POMC and AgRP Neurons in Male Mice

PubMed Central

Nestor, Casey C; Qiu, Jian; Padilla, Stephanie L.; Zhang, Chunguang; Bosch, Martha A.; Fan, Wei; Aicher, Sue A.; Palmiter, Richard D.

2016-01-01

Kisspeptin (Kiss1) neurons are essential for reproduction, but their role in the control of energy balance and other homeostatic functions remains unclear. Proopiomelanocortin (POMC) and agouti-related peptide (AgRP) neurons, located in the arcuate nucleus (ARC) of the hypothalamus, integrate numerous excitatory and inhibitory inputs to ultimately regulate energy homeostasis. Given that POMC and AgRP neurons are contacted by Kiss1 neurons in the ARC (Kiss1ARC) and they express androgen receptors, Kiss1ARC neurons may mediate the orexigenic action of testosterone via POMC and/or AgRP neurons. Quantitative PCR analysis of pooled Kiss1ARC neurons revealed that mRNA levels for Kiss1 and vesicular glutamate transporter 2 were higher in castrated male mice compared with gonad-intact males. Single-cell RT-PCR analysis of yellow fluorescent protein (YFP) ARC neurons harvested from males injected with AAV1-EF1α-DIO-ChR2:YFP revealed that 100% and 88% expressed mRNAs for Kiss1 and vesicular glutamate transporter 2, respectively. Whole-cell, voltage-clamp recordings from nonfluorescent postsynaptic ARC neurons showed that low frequency photo-stimulation (0.5 Hz) of Kiss1-ChR2:YFP neurons elicited a fast glutamatergic inward current in POMC and AgRP neurons. Paired-pulse, photo-stimulation revealed paired-pulse depression, which is indicative of greater glutamate release, in the castrated male mice compared with gonad-intact male mice. Group I and group II metabotropic glutamate receptor agonists depolarized and hyperpolarized POMC and AgRP neurons, respectively, which was mimicked by high frequency photo-stimulation (20 Hz) of Kiss1ARC neurons. Therefore, POMC and AgRP neurons receive direct steroid- and frequency-dependent glutamatergic synaptic input from Kiss1ARC neurons in male mice, which may be a critical pathway for Kiss1 neurons to help coordinate energy homeostasis and reproduction. PMID:27093227

Facile preparation of dendritic Ag-Pd bimetallic nanostructures on the surface of Cu foil for application as a SERS-substrate

NASA Astrophysics Data System (ADS)

Yi, Zao; Tan, Xiulan; Niu, Gao; Xu, Xibin; Li, Xibo; Ye, Xin; Luo, Jiangshan; Luo, Binchi; Wu, Weidong; Tang, Yongjian; Yi, Yougen

2012-05-01

Dendritic Ag-Pd bimetallic nanostructures have been synthesized on the surface of Cu foil via a multi-stage galvanic replacement reaction (MGRR) of Ag dendrites in a Na2PdCl4 solution. After five stages of replacement reaction, one obtained structures with protruding Ag-Pd flakes; these will mature into many porous structures with a few Ag atoms that are left over dendrites. The dendritic Ag-Pd bimetallic nanostructures were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS). The morphology of the products strongly depended on the stage of galvanic replacement reaction and reaction temperature. The morphology and composition-dependent surface-enhanced Raman scattering (SERS) of the as-synthesized Ag-Pd bimetallic nanostructures were investigated. The effectiveness of these dendritic Ag-Pd bimetallic nanostructures on the surface of Cu foil as substrates toward SERS detection was evaluated by using rhodamine 6G (R6G) as a probe molecule. The results indicate that as-synthesized dendritic Ag-Pd bimetallic nanostructures are good candidates for SERS spectroscopy.

An approach for scalable production of silver (Ag) decorated WS2 nanosheets

NASA Astrophysics Data System (ADS)

Sumesh, C. K.; Kapatel, Sanni; Chaudhari, Arti

2018-05-01

In the Present study we report the synthesis of Ag nanoparticles (NPs) decorated WS2 nanosheets by sonochemical exfoliation followed by simple chemical reduction process at room temperature. The morphology and microstructure of the as-synthesized Ag-WS2 nanocomposite were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and optical absorption (UV-Vis.) spectroscopy. X-ray and TEM analysis shows the presence of Ag with significant peak over 38.08°, 44.22°, 64.37° and 77.33° at 2θ angle for (111), (200), (220) and (311) respectively. The Ag nanoparticles are randomly distributed throughout the surface of the WS2 nanosheets without undergoing further oxidation during the formation of composites. The formation of Ag-WS2 nanocomposites shows a clear blue shift in the absorption as we obtained the characteristics absorption valleys at 456, 536 and 631 nm from the UV Vis spectroscopy analysis compared to pure WS2 nanosheets. Henceforth a facile method for the Ag decoration on WS2 nanosheets was put forward and briefly discussed. The proposed synthesis method is very promising for the low cost and large-scale synthesis of other noble metal incorporation TMDC compounds.

Antimicrobial and anticancer activity of AgNPs coated with Alphonsea sclerocarpa extract.

PubMed

Doddapaneni, Suman Joshi D S; Amgoth, Chander; Kalle, Arunasree M; Suryadevara, Surya Narayana; Alapati, Krishna Satya

2018-03-01

The synthesis and characterization of an aggregate of AgNPs coated with plant extract (PE) from Alphonsea sclerocarpa and its significant antimicrobial activity and inhibition on K562 (blood cancer) cells have been appended in the article. Synthesis of aggregate [(AgNPs)-(PE)] has been followed by a facile eco-friendly approach without using any harmful chemicals. The morphology of an aggregate [(AgNPs)-(PE)] was confirmed by TEM and SEM microscopic characterizations. Properties like solid state, the presence of functional groups, and elemental composition have been characterized through the XRD, FTIR, and EDAX. The biocompatibility of synthesized aggregate of [(AgNPs)-(PE)] was confirmed by the MTT assay. An in vitro cell (HEK293)-based studies were performed for the biocompatibility tests and it is found that the aggregate [(AgNPs)-(PE)] is not harmful to normal/healthy cells. Even though A. sclerocarpa show the antimicrobial (antibacterial and antifungal) activity, it has been further enhanced with the developed aggregate of [(AgNPs)-(PE)]. Furthermore, it has been extended to examine the cellular inhibition on K562 cells and obtained > 75% cell inhibition for 24 h treated cells.

Spectroscopy of the low-frequency vibrational modes of CH3+ isotopologues

NASA Astrophysics Data System (ADS)

Asvany, Oskar; Thorwirth, Sven; Redlich, Britta; Schlemmer, Stephan

2018-05-01

The low-frequency stretching and bending vibrations of the isotopologues CH2D+,CD2H+ and CD3+ have been recorded at low temperature and low resolution. For this, a cryogenic 22-pole trapping machine coupled to an IR beamline of the FELIX free electron laser facility has been used. To record the overview spectra, the laser induced reactions CDm Hn+ + H2 → hν CDm-1 Hn+1+ +HD have been applied for these species. As this scheme is not applicable to CH3+, the latter has been tagged with He and subsequently dissociated by the IR beam. For the resulting CH3+ -He spectrum, broad features are observed below 1000 cm-1 possibly related to vibrational motions involving the He atom. The extracted vibrational band positions for all species are compared to results from high-level quantum-chemical calculations.

Louisiana SIP: LAC 33:III Ch 2132. Stage II Vapor Recovery Systems for Control of Vehicle Refuelling Emissions at Gasoline Dispensing Facilities; SIP effective 2011-08-04 (LAd34) and 2016-02-29 (LAd47) to 2017-09-27

EPA Pesticide Factsheets

Louisiana SIP: LAC 33:III Ch 2132. Stage II Vapor Recovery Systems for Control of Vehicle Refuelling Emissions at Gasoline Dispensing Facilities; SIP effective 2011-08-04 (LAd34) and 2016-02-29 (LAd47) to 2017-09-27

Nanoporous Ag prepared from the melt-spun Cu-Ag alloys

NASA Astrophysics Data System (ADS)

Li, Guijing; Song, Xiaoping; Sun, Zhanbo; Yang, Shengchun; Ding, Bingjun; Yang, Sen; Yang, Zhimao; Wang, Fei

2011-07-01

Nanoporous Ag ribbons with different morphology and porosity were achieved by the electrochemical corrosion of the melt-spun Cu-Ag alloys. The Cu-rich phase in the alloys was removed, resulting in the formation of the nanopores distributed across the whole ribbon. It is found that the structures, morphology and porosity of the nanoporous Ag ribbons were dependent on the microstructures of the parent alloys. The most of ligaments presented a rod-like shape due to the formation of pseudoeutectic microstructure in the melt-spun Cu 55Ag 45 and Cu 70Ag 30 alloys. For nanoporous Ag prepared from Cu 85Ag 15 alloys, the ligaments were camber-like because of the appearance of the divorced microstructures. Especially, a novel bamboo-grove-like structure could be observed at the cross-section of the nanoporous Ag ribbons. The experiment reveals that nanoporous Ag ribbons exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) effect, but a slight difference existed due to the discrepancy of their morphology.

Cs2AgBiBr6 single-crystal X-ray detectors with a low detection limit

NASA Astrophysics Data System (ADS)

Pan, Weicheng; Wu, Haodi; Luo, Jiajun; Deng, Zhenzhou; Ge, Cong; Chen, Chao; Jiang, Xiaowei; Yin, Wan-Jian; Niu, Guangda; Zhu, Lujun; Yin, Lixiao; Zhou, Ying; Xie, Qingguo; Ke, Xiaoxing; Sui, Manling; Tang, Jiang

2017-11-01

Sensitive X-ray detection is crucial for medical diagnosis, industrial inspection and scientific research. The recently described hybrid lead halide perovskites have demonstrated low-cost fabrication and outstanding performance for direct X-ray detection, but they all contain toxic Pb in a soluble form. Here, we report sensitive X-ray detectors using solution-processed double perovskite Cs2AgBiBr6 single crystals. Through thermal annealing and surface treatment, we largely eliminate Ag+/Bi3+ disordering and improve the crystal resistivity, resulting in a detector with a minimum detectable dose rate as low as 59.7 nGyair s-1, comparable to the latest record of 0.036 μGyair s-1 using CH3NH3PbBr3 single crystals. Suppressed ion migration in Cs2AgBiBr6 permits relatively large external bias, guaranteeing efficient charge collection without a substantial increase in noise current and thus enabling the low detection limit.

In situ solid-state fabrication of hybrid AgCl/AgI/AgIO3 with improved UV-to-visible photocatalytic performance.

PubMed

Xie, Jing; Cao, Yali; Jia, Dianzeng; Li, Yizhao; Wang, Kun; Xu, Hui

2017-09-28

The AgCl/AgI/AgIO 3 composites were synthesized through a one-pot room-temperature in situ solid-state approach with the feature of convenient and eco-friendly. The as-prepared composites exhibit superior photocatalytic performance than pure AgIO 3 for the degradation of methyl orange (MO) under both UV and visible light irradiation. The photodegradation rate toward MO of the AgCl/AgI/AgIO 3 photocatalyst can reach 100% after 12 min irradiation under UV light, or 85.4% after 50 min irradiation under visible light, being significantly higher than AgCl, AgI, AgIO 3 and AgI/AgIO 3 . In addition, the AgCl/AgI/AgIO 3 photocatalyst possesses strong photooxidation ability for the degradation of rhodamine B (RhB), methylene blue (MB), phenol, bisphenol A (BPA) and tetracycline hydrochloride under visible light irradiation. The reactive species capture experiments confirmed that the h + and •O 2- play an essential role during the photocatalytic process under UV light or visible light irradiation. The enhanced effect may be beneficial from the enhanced light adsorption in full spectrum and increased separation efficiency of photogenerated hole-electron pairs, which can be ascribed to the synergistic effect among AgCl, AgI and AgIO 3 nanoplates in AgCl/AgI/AgIO 3 composites.

Protective effect of ascorbic acid on netilmicin-induced lipid profile and peroxidation parameters in rabbit blood plasma.

PubMed

Devbhuti, Pritesh; Sikdar, Debasis; Saha, Achintya; Sengupta, Chandana

2011-01-01

A drug may cause alteration in blood-lipid profile and induce lipid peroxidation phenomena on administration in the body. Antioxidant may play beneficial role to control the negative alteration in lipid profile and lipid peroxidation. In view of this context, the present in vivo study was carried out to evaluate the role of ascorbic acid as antioxidant on netilmicin-induced alteration of blood lipid profile and peroxidation parameters. Rabbits were used as experimental animals and blood was collected to estimate blood-lipid profiles, such as total cholesterol (TCh), high density lipoprotein cholesterol (HDL-Ch), low density lipoprotein cholesterol (LDL-Ch), very low density lipoprotein cholesterol (VLDL-Ch), triglycerides (Tg), phospholipids (PL), and total lipids (TL), as well as peroxidation parameters, such as malondialdehyde (MDA), 4-hydroxy-2-nonenal (HNE), reduced glutathione (GSH) and nitric oxide (NO). The results revealed that netilmicin caused significant enhancement of MDA, HNE, TCh, LDL-Ch, VLDL-Ch, Tg levels and reduction in GSH, NO, HDL-Ch, PL, TL levels. On co-administration, ascorbic acid was found to be effective in reducing netilmicin-induced negative alterations of the above parameters.

DOSE PROFILE MODELING OF IDAHO NATIONAL LABORATORY’S ACTIVE NEUTRON INTERROGATION TEST FACILITY

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

D. L. Chichester; E. H. Seabury; J. M. Zabriskie

2009-06-01

A new research and development laboratory has been commissioned at Idaho National Laboratory for performing active neutron interrogation research and development. The facility is designed to provide radiation shielding for DT fusion (14.1 MeV) neutron generators (2 x 108 neutrons per second), DD fusion (2.5 MeV) neutron generators (up to 2 x 106 neutrons per second), and 252Cf spontaneous fission neutron sources (6.7 x 107 neutrons per second, 30 micrograms). Shielding at the laboratory is comprised of modular concrete shield blocks 0.76 m thick with tongue-in-groove features to prevent radiation streaming, arranged into one small and one large test vault.more » The larger vault is designed to allow operation of the DT generator and has walls 3.8 m tall, an entrance maze, and a fully integrated electrical interlock system; the smaller test vault is designed for 252Cf and DD neutron sources and has walls 1.9 m tall and a simple entrance maze. Both analytical calculations and numerical simulations were used in the design process for the building to assess the performance of the shielding walls and to ensure external dose rates are within required facility limits. Dose rate contour plots have been generated for the facility to visualize the effectiveness of the shield wall and entrance maze and to illustrate the spatial profile of the radiation dose field above the facility and the effects of skyshine around the vaults.« less

Inverse modelling of European CH4 emissions during 2006-2012 using different inverse models and reassessed atmospheric observations

NASA Astrophysics Data System (ADS)

Bergamaschi, Peter; Karstens, Ute; Manning, Alistair J.; Saunois, Marielle; Tsuruta, Aki; Berchet, Antoine; Vermeulen, Alexander T.; Arnold, Tim; Janssens-Maenhout, Greet; Hammer, Samuel; Levin, Ingeborg; Schmidt, Martina; Ramonet, Michel; Lopez, Morgan; Lavric, Jost; Aalto, Tuula; Chen, Huilin; Feist, Dietrich G.; Gerbig, Christoph; Haszpra, László; Hermansen, Ove; Manca, Giovanni; Moncrieff, John; Meinhardt, Frank; Necki, Jaroslaw; Galkowski, Michal; O'Doherty, Simon; Paramonova, Nina; Scheeren, Hubertus A.; Steinbacher, Martin; Dlugokencky, Ed

2018-01-01

We present inverse modelling (top down) estimates of European methane (CH4) emissions for 2006-2012 based on a new quality-controlled and harmonised in situ data set from 18 European atmospheric monitoring stations. We applied an ensemble of seven inverse models and performed four inversion experiments, investigating the impact of different sets of stations and the use of a priori information on emissions. The inverse models infer total CH4 emissions of 26.8 (20.2-29.7) Tg CH4 yr-1 (mean, 10th and 90th percentiles from all inversions) for the EU-28 for 2006-2012 from the four inversion experiments. For comparison, total anthropogenic CH4 emissions reported to UNFCCC (bottom up, based on statistical data and emissions factors) amount to only 21.3 Tg CH4 yr-1 (2006) to 18.8 Tg CH4 yr-1 (2012). A potential explanation for the higher range of top-down estimates compared to bottom-up inventories could be the contribution from natural sources, such as peatlands, wetlands, and wet soils. Based on seven different wetland inventories from the Wetland and Wetland CH4 Inter-comparison of Models Project (WETCHIMP), total wetland emissions of 4.3 (2.3-8.2) Tg CH4 yr-1 from the EU-28 are estimated. The hypothesis of significant natural emissions is supported by the finding that several inverse models yield significant seasonal cycles of derived CH4 emissions with maxima in summer, while anthropogenic CH4 emissions are assumed to have much lower seasonal variability. Taking into account the wetland emissions from the WETCHIMP ensemble, the top-down estimates are broadly consistent with the sum of anthropogenic and natural bottom-up inventories. However, the contribution of natural sources and their regional distribution remain rather uncertain. Furthermore, we investigate potential biases in the inverse models by comparison with regular aircraft profiles at four European sites and with vertical profiles obtained during the Infrastructure for Measurement of the European Carbon

Pd-catalyzed intramolecular oxidative C-H amination: synthesis of carbazoles.

PubMed

Youn, So Won; Bihn, Joon Hyung; Kim, Byung Seok

2011-07-15

A Pd-catalyzed oxidative C-H amination of N-Ts-2-arylanilines under ambient temperature using Oxone as an inexpensive, safe, and easy-to-handle oxidant has been developed. This process represents a green and practical method for the facile construction of carbazoles with a broad substrate scope and wide functional group tolerance. © 2011 American Chemical Society

Fabrication of Ag-Au bimetallic nanoparticles by laser-induced dewetting of bilayer films

NASA Astrophysics Data System (ADS)

Oh, Yoonseok; Lee, Jeeyoung; Lee, Myeongkyu

2018-03-01

We here show that Ag-Au bimetallic nanoparticles (NPs) can be produced by dewetting an Ag/Au bilayer film coated on glass using a nanosecond-pulsed laser beam. Elemental analysis revealed that the obtained bimetallic NPs are Ag-Au alloys, with two elements well mixed over the whole volume of the particle. The composition of the produced particles was controllable by changing the relative thickness of each layer. The localized surface plasmon resonance (LSPR) peak was red-shifted with an increasing Au content and the LSPR wavelength could be tuned from 415 to 525 nm by varying the alloy composition. A film area of several square centimeters could be transformed into Ag-Au NPs by a single laser pulse of 6 ns duration. This study provides a facile and scalable route to prepare bimetallic NPs for plasmonic and other applications.

On the Jupiter's ephemeris in the Ch'i-Yao Jang-Tsai-Chüch.

NASA Astrophysics Data System (ADS)

Niu, Weixing; Jiang, Xiaoyuan

Jupiter's ephemeris preserved in the Ch'i-Yao Jang-Tsai-Chüch is interpreted. Then the time and position coordinates of Jupiter's first stationary point, second stationary point, first visibility in the east and last visibility in the west, which recorded in the ephemeris are analysed. The accuracy of the ephemeris is also discussed. Finally, it is identified that the ephemeris has been used as an astrological handbook by Japanese astrologers in 973 - 1132.

AgCl/Ag3PO4: A stable Ag-Based nanocomposite photocatalyst with enhanced photocatalytic activity for the degradation of parabens.

PubMed

Guo, Jianhao; Shi, Huixian; Huang, Xiaobo; Shi, Huifang; An, Zhongfu

2018-04-01

An AgCl/Ag 3 PO 4 composite has been successfully fabricated by a simple desorption-precipitation method. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV/Vis), and photoluminescence (PL) have been used to study the structural and physicochemical characteristics of the AgCl/Ag 3 PO 4 composite. The photocatalytic activity of the AgCl/Ag 3 PO 4 composite has been tested by the degradation of parabens under visible-light irradiation. 100% of MPB was degraded within 40 min in the AgCl/Ag 3 PO 4 -visible light system. Moreover, the photocatalytic activity of AgCl/Ag 3 PO 4 remained at 94% of the original level after five runs, which was much higher than that of pure Ag 3 PO 4 (25%). The obtained results confirmed that the AgCl/Ag 3 PO 4 composite exhibited significantly higher photocatalytic performance and improved stability compared with bare Ag 3 PO 4 . The enhanced photocatalytic performance of the AgCl/Ag 3 PO 4 composite could be mainly attributed to highly efficient charge separation through a synergistic effect of AgCl, Ag 3 PO 4 , and in situ photo-reduced Ag nanoparticles. Trapping experiments confirmed h + and ·O 2 - to be the two main active species in the photocatalytic process. Finally, a possible photocatalytic mechanism for the charge-transfer process is proposed to account for the enhanced photocatalytic performance of the AgCl/Ag 3 PO 4 composite. Copyright © 2018 Elsevier Inc. All rights reserved.

Synthesis and ion transport characterization of hot-pressed Ag+ ion conducting glass-polymer electrolytes

NASA Astrophysics Data System (ADS)

Chandra, A.

2013-07-01

Synthesis and ion transport characterization of a new Ag+ ion conducting glass-polymer electrolyte (GPE) films: (1- x) PEO: x [0.8(0.75AgI:0.25AgCl):0.2(Ag2O:V2O5)], where 0 < x < 50 wt%, are reported. The composition: 70PEO: 30[0.8(0.75AgI:0.25AgCl):0.2(Ag2O:V2O5)] with conductivity ( σ) 7.7 × 10-7 Ω-1 cm-1 is identified as highest conducting composition referred to as the optimum conducting composition (OCC). Approximately two and half orders of conductivity enhancement have been achieved in OCC from that of the pure polymer poly(ethylene oxide). The glass-polymer complexation is confirmed by the XRD, FTIR, DSC and TGA techniques. The ion transport behavior has been reported on the basis of experimental measurements on some basic ionic parameters. A solid state polymeric battery has been fabricated by using GPE OCC as an electrolyte and their important cell parameters have been also calculated from the discharge profiles.

Room-temperature Pd-catalyzed C-H chlorination by weak coordination: one-pot synthesis of 2-chlorophenols with excellent regioselectivity.

PubMed

Sun, Xiuyun; Sun, Yonghui; Zhang, Chao; Rao, Yu

2014-02-07

A room-temperature Pd(II)-catalyzed regioselective chlorination reaction has been developed for a facile one-pot synthesis of a broad range of 2-chlorophenols. The reaction demonstrates an excellent regioselectivity and reactivity for C-H chlorination. This reaction represents one of the rare examples of mild C-H functionalization at ambient temperature.

Z-scheme Ag3PO4/POM/GO heterojunction with enhanced photocatalytic performance for degradation and water splitting.

PubMed

Liu, Guodong; Zhao, Xinfu; Zhang, Jian; Liu, Shaojie; Sha, Jingquan

2018-05-01

To develop solar light-driven photocatalysts with high activity and structural stability, Ag3PO4/POM/GO heterojunction has been successfully prepared by a facile method at room temperature. Ag3PO4/POM/GO shows remarkably enhanced activity and stability for photocatalytic degradation and H2 production from water-splitting under simulated solar light. The degradation rate of Ag3PO4/POM/GO is 1.8 times and 1.2 times those of Ag3PO4 and Ag3PO4/POMs, respectively. H2 production using Ag3PO4/POM/GO is 2.0 times that of Ag3PO4/GO. The enhanced photocatalytic performance of Ag3PO4/POM/GO is attributed to the increased surface area, electronegativity and structure stability. The Z-scheme system of Ag3PO4/POM/GO effectively promotes charge separation, resulting in enhanced photocatalytic performance under simulated solar light.

Tyrphostin AG17 inhibits adipocyte differentiation in vivo and in vitro.

PubMed

Camacho, Alberto; Segoviano-Ramírez, Juan Carlos; Sánchez-Garcia, Adriana; de Jesus Herrera-de la Rosa, Jose; García-Juarez, Jaime; Hernandez-Puente, Carlos Alberto; Calvo-Anguiano, Geovana; Maltos-Uro, Sergio Rodolfo; Olguin, Alejandra; Gojon-Romanillos, Gabriel; Gojon-Zorrilla, Gabriel; Ortiz-Lopez, Rocio

2018-05-29

Excessive subcutaneous adiposity in obesity is associated to positive white adipocyte tissue (WAT) differentiation (adipogenesis) and WAT expandability. Here, we hypothesized that supplementation with the insulin inhibitor and mitochondrial uncoupler, Tyrphostin (T-AG17), in vitro and in vivo inhibits adipogenesis and adipocyte hypertrophy. We used a 3T3-L1 proadipocyte cell line to identify the potential effect of T-AG17 on adipocyte differentiation and fat accumulation in vitro. We evaluated the safety of T-AG17 and its effects on physiological and molecular metabolic parameters including hormonal profile, glucose levels, adipogenesis and adipocyte hypertrophy in a diet-induced obesity model using C57BL/6 mice. We found that T-AG17 is effective in preventing adipogenesis and lipid synthesis in the 3T3-L1 cell line, as evidenced by a significant decrease in oil red staining (p < 0.05). In obese C57BL/6 mice, oral administration of T-AG17 (0.175 mg/kg for 2 weeks) lead to decreased fat accumulation and WAT hypertrophy. Further, T-AG17 induced adipocyte apoptosis by activating caspase-3. In the hepatocytes of obese mice, T-AG17 promoted an increase in the size of lipid inclusions, which was accompanied by glycogen accumulation. T-AG17 did not alter serum biochemistry, including glucose, insulin, leptin, free fatty acids, creatinine, and aspartate aminotransferase. T-AG17 promotes adipocyte apoptosis in vivo and is an effective modulator of adipocyte differentiation and WAT hypertrophy in vitro and in vivo. Therefore, T-AG17 may be useful as a pharmacological obesity treatment.

Facile fabrication of Ag dendrite-integrated anodic aluminum oxide membrane as effective three-dimensional SERS substrate

NASA Astrophysics Data System (ADS)

Zhang, Cong-yun; Lu, Ya; Zhao, Bin; Hao, Yao-wu; Liu, Ya-qing

2016-07-01

A novel surface enhanced Raman scattering (SERS)-active substrate has been successfully developed, where Ag-dendrites are assembled on the surface and embedded in the channels of anodic aluminum oxide (AAO) membrane, via electrodeposition in AgNO3/PVP aqueous system. Reaction conditions were systematically investigated to attain the best Raman enhancement. The growth mechanism of Ag dendritic nanostructures has been proposed. The Ag dendrite-integrated AAO membrane with unique hierarchical structures exhibits high SERS activity for detecting rhodamine 6G with a detection limit as low as 1 × 10-11 M. Furthermore, the three-dimensional (3D) substrates display a good reproducibility with the average intensity variations at the major Raman peak less than 12%. Most importantly, the 3D SERS substrates without any surface modification show an outstanding SERS response for the molecules with weak affinity for noble metal surfaces. The potential application for the detection of polycyclic aromatic hydrocarbons (PAHs) was evaluated with fluoranthene as Raman target molecule and a sensitive SERS detection with a limit down to 10-8 M was reached. The 3D SERS-active substrate shows promising potential for rapid detection of trace organic pollutants even weak affinity molecules in the environment.

The green synthesis of Ag/ZnO in montmorillonite with enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Sohrabnezhad, Sh.; Seifi, A.

2016-11-01

The Ag/ZnO-MMT nanocomposite was prepared using urtica dioica leaf extract. To improve the photocatalytic properties of ZnO-MMT nanocomposite, silver metal nanoparticles was deposited over nanocomposite. Zn(CH3COO)2, AgNO3 and Urtica dioica leaf extract were used as a zinc, silver precursor and reducing agent, respectively. The nanocomposite was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy (DRS). The powder X-ray diffraction showed that Ag/ZnO nanoparticles located on the surface MMT layers. The diffuse reflectance spectra of nanocomposite indicated a strong surface plasmon resonance (SPR) absorption band in the visible region, resulting from metallic Ag nanoparticles. TEM image demonstrated the presence of silver nanoparticles with an average size of 2-4 nm over both MMT and flower-shape ZnO. The photocatalytic activity of nanocomposite was studied for destructive reaction methylene blue dye under visible light. In addition, the effects of different parameters such as amount of nanocomposite, concentration of the dye and pH of the solution were studied. The results showed that modiffication of ZnO-MMT nanocomposite with silver nanoparticles increased the percentage of discoloration methylene blue (MB) from 38.95 to 91.95. MMT matrix showed an important role in the reduction of recombination of electron-hole in nanocomposite.

Simplifying the growth of hybrid single-crystals by using nanoparticle precursors: the case of AgI

NASA Astrophysics Data System (ADS)

Xu, Biao; Wang, Ruji; Wang, Xun

2012-03-01

We report the synthesis of a series of AAgmIn single-crystals within 24 h, at room temperature, utilizing AgI nanoparticles (NPs) as the precursor. The AgI NPs impart high reactivity under mild conditions and favor the growth kinetics. 0D, 1D and 2D iodoargentate crystals can be obtained. This work represents the first application of NPs in the field of organo-metal-halide crystals and will inspire the design of other AMmXn crystals.We report the synthesis of a series of AAgmIn single-crystals within 24 h, at room temperature, utilizing AgI nanoparticles (NPs) as the precursor. The AgI NPs impart high reactivity under mild conditions and favor the growth kinetics. 0D, 1D and 2D iodoargentate crystals can be obtained. This work represents the first application of NPs in the field of organo-metal-halide crystals and will inspire the design of other AMmXn crystals. Electronic supplementary information (ESI) available: XPS spectra of AgI NPs, schematic representation of the formation process of [Ag4I8]4- in 2, UV-Vis spectra of the DTMA-Ag-I clusters, analysis of force balance of a crystal at the interface between H2O and CH2Cl2 and crystal structure depiction of 1-4. CIF files of 1-4 are also provided. CCDC reference numbers 863848, 863849, 863850 and 863851. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2nr30139c

Rate constants for the reactions of OH with CH3Cl, CH2Cl2, CHCl3, and CH3Br

NASA Technical Reports Server (NTRS)

Hsu, K.-J.; Demore, W. B.

1994-01-01

Rate constants for the reactions of OH with CH3Cl, CH2Cl2, CHCl3, and CH3Br have been measured by a relative rate technique in which the reaction rate of each compound was compared to that of HFC-152a (CH3CHF2) and (for CH2Cl2) HFC-161 (CH3CH2F). Using absolute rate constants for HFC-152a and HFC-161, which we have determined relative to those for CH4, CH3CCl3, and C2H6, temperature dependent rate constants of both compounds were derived. The derived rate constant for CH3Br is in good agreement with recent absolute measurements. However, for the chloromethanes all the rate constants are lower at atmospheric temperatures than previously reported, especially for CH2Cl2 where the present rate constant is about a factor of 1.6 below the JPL 92-20 value. The new rate constant appears to resolve a discrepancy between the observed atmospheric concentrations and those calculated from the previous rate constant and estimated release rates.

Continuous-flow biosynthesis of Au-Ag bimetallic nanoparticles in a microreactor

NASA Astrophysics Data System (ADS)

Liu, Hongyu; Huang, Jiale; Sun, Daohua; Odoom-Wubah, Tareque; Li, Jun; Li, Qingbiao

2014-11-01

Herein, a microfluidic biosynthesis of Au-Ag bimetallic nanoparticle (NP) in a tubular microreactor, based on simultaneous reduction of HAuCl4 and AgNO3 precursors in the presence of Cacumen Platycladi ( C. Platycladi) extract was studied. The flow velocity profile was numerically analyzed with computational fluid dynamics. Au-Ag bimetallic NPs with Ag/Au molar ratios of 1:1 and 2:1 were synthesized, respectively. The alloy formation, morphology, structure, and size were investigated by UV-Vis spectra analysis, transmission electron microscopy (TEM), high resolution TEM, scanning TEM, and energy-dispersive X-ray analysis. In addition, the effects of volumetric flow rate, reaction temperature, and concentration of C. Platycladi extract and NaOH on the properties of the as-synthesized Au-Ag bimetallic NPs were investigated. The results indicated that these factors could not only affect the molar ratios of the two elements in the Au-Ag bimetallic NPs, but also affect particle size which can be adjusted from 3.3 to 5.6 nm. The process was very rapid and green, since a microreactor was employed with no additional synthetic reagents used. This work is anticipated to provide useful parameters for continuous-flow biosynthesis of bimetallic NPs in microreactors.

Validation of GOSAT/TANSO-FTS TIR V01.00 CO2 and CH4 products

NASA Astrophysics Data System (ADS)

Saitoh, N.; Kimoto, S.; Sugimura, R.; Imasu, R.; Kawakami, S.; Shiomi, K.; Machida, T.; Sawa, Y.; Matsuda, H.

2014-12-01

Greenhouse Gases Observing Satellite (GOSAT) has been making observations continuously for more than five years since its launch on 23 January 2009. Thermal and Near-infrared Sensor for Carbon Observation Fourier Transform Spectrometer (TANSO-FTS) on board the GOSAT simultaneously observes column abundances and profiles of CO2 and CH4 in the same field of view, from the shortwave infrared (SWIR) and thermal infrared (TIR) bands, respectively. We have just released the latest TIR CO2 and CH4 products, V01.00, to registered researchers. To validate the data quality of the V01.00 TIR CO2 product, we compared the TIR data with CO2 data obtained by Continuous CO2 Measuring Equipment (CME) on board JAL aircraft in Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) project. The aircraft CO2 data obtained during the level flights were compared with the V01.00 TIR upper tropospheric CO2 data. The CONTRAIL CO2 "profile" data obtained during the ascending and descending flights over several airports were compared with the TIR CO2 profiles. In the profile comparisons, we applied the TIR averaging kernel functions to the coincident CONTRAIL CO2 profiles. The V01.00 upper atmospheric CO2 data agreed to the CONTRAIL level flight CO2 data on average within 0.5-1%. Some TIR CO2 data showed relatively large differences from the nearest aircraft data, which suggests the existence of several problems such as L1B spectral calibration and nighttime cloud detection issues. The TIR V01.00 CO2 profile data from 9 to 13 km showed better agreement to CONTRAIL CO2 data than the a priori. However, the TIR CO2 data at around and below 5 km had low bias of 1-1.5%. The TIR V01.00 CH4 data generally showed reasonable latitudinal distributions as the previous version. In the Antarctic, unexpected high amounts of CH4 were seen in upper troposphere and lower stratosphere in autumn. This is probably because of the problem of simultaneously retrieved ozone concentration.

A mathematical simulation model of the CH-47B helicopter, volume 1

NASA Technical Reports Server (NTRS)

Weber, J. M.; Liu, T. Y.; Chung, W.

1984-01-01

A nonlinear simulation model of the CH-47B helicopter was adapted for use in the NASA Ames Research Center (ARC) simulation facility. The model represents the specific configuration of the ARC variable stability CH-47B helicopter and will be used in ground simulation research and to expedite and verify flight experiment design. Modeling of the helicopter uses a total force approach in six rigid body degrees of freedom. Rotor dynamics are simulated using the Wheatlely-Bailey equations including steady-state flapping dynamics. Also included in the model is the option for simulation of external suspension, slung-load equations of motion.

Growth rate of YBCO-Ag superconducting single grains

NASA Astrophysics Data System (ADS)

Congreve, J. V. J.; Shi, Y. H.; Dennis, A. R.; Durrell, J. H.; Cardwell, D. A.

2017-12-01

The large scale use of (RE)Ba2Cu3O7 bulk superconductors, where RE=Y, Gd, Sm, is, in part, limited by the relatively poor mechanical properties of these inherently brittle ceramic materials. It is reported that alloying of (RE)Ba2Cu3O7 with silver enables a significant improvement in the mechanical strength of bulk, single grain samples without any detrimental effect on their superconducting properties. However, due to the complexity and number of inter-related variables involved in the top seeded melt growth (TSMG) process, the growth of large single grains is difficult and the addition of silver makes it even more difficult to achieve successful growth reliably. The key processing variables in the TSMG process include the times and temperatures of the stages within the heating profile, which can be derived from the growth rate during the growth process. To date, the growth rate of the YBa2Cu3O7-Ag system has not been reported in detail and it is this lacuna that we have sought to address. In this work we measure the growth rate of the YBCO-Ag system using a method based on continuous cooling and isothermal holding (CCIH). We have determined the growth rate by measuring the side length of the crystallised region for a number of samples for specified isothermal hold temperatures and periods. This has enabled the growth rate to be modelled and from this an optimized heating profile for the successful growth of YBCO-Ag single grains to be derived.

3D flower-like hierarchical Ag@nickel-cobalt hydroxide microsphere with enhanced electrochemical properties

NASA Astrophysics Data System (ADS)

Lv, Zijian; Zhong, Qin; Bu, Yunfei; Wu, Junpeng

2016-10-01

The morphology and electrical conductivity are essential to electrochemical performance of electrode materials in renewable energy conversion and storage technologies such as fuel cells and supercapacitors. Here, we explored a facile method to grow Ag@nickel-cobalt layered double hydroxide (Ag@Ni/Co-LDHs) with 3D flower-like microsphere structure. The results show the morphology of Ni/Co-LDHs varies with the introduction of Ag species. The prepared Ag@Ni/Co-LDHs not only exhibits an open hierarchical structure with high specific capacitance but also shows good electrical conductivity to support fast electron transport. Benefiting from the unique structural features, these flower-like Ag@Ni/Co-LDHs microspheres have impressive specific capacitance as high as 1768 F g-1 at 1 A g-1. It can be concluded that engineering the structure of the electrode can increase the efficiency of the specific capacitance as a battery-type electrode for hybrid supercapacitors.

Facile fabrication of large-grain CH3NH3PbI3−xBrx films for high-efficiency solar cells via CH3NH3Br-selective Ostwald ripening

PubMed Central

Yang, Mengjin; Zhang, Taiyang; Schulz, Philip; Li, Zhen; Li, Ge; Kim, Dong Hoe; Guo, Nanjie; Berry, Joseph J.; Zhu, Kai; Zhao, Yixin

2016-01-01

Organometallic halide perovskite solar cells (PSCs) have shown great promise as a low-cost, high-efficiency photovoltaic technology. Structural and electro-optical properties of the perovskite absorber layer are most critical to device operation characteristics. Here we present a facile fabrication of high-efficiency PSCs based on compact, large-grain, pinhole-free CH3NH3PbI3−xBrx (MAPbI3−xBrx) thin films with high reproducibility. A simple methylammonium bromide (MABr) treatment via spin-coating with a proper MABr concentration converts MAPbI3 thin films with different initial film qualities (for example, grain size and pinholes) to high-quality MAPbI3−xBrx thin films following an Ostwald ripening process, which is strongly affected by MABr concentration and is ineffective when replacing MABr with methylammonium iodide. A higher MABr concentration enhances I–Br anion exchange reaction, yielding poorer device performance. This MABr-selective Ostwald ripening process improves cell efficiency but also enhances device stability and thus represents a simple, promising strategy for further improving PSC performance with higher reproducibility and reliability. PMID:27477212

Extraordinary Thermoelectric Performance Realized in Hierarchically Structured AgSbSe2 with Ultralow Thermal Conductivity.

PubMed

Gao, Weihong; Wang, Zhenyou; Huang, Jin; Liu, Zihang

2018-05-24

Thermoelectric conversion from low-grade heat to electricity is regarded as the highly reliable and environmentally friendly technology in energy-harvesting area. However, how to develop efficient thermoelectric materials using a simple fabrication method is still a critical challenge in thermoelectric community. Here, we first fabricate the high thermoelectric performance of Ca-doped AgSbSe 2 with a hierarchical microstructure using a facile approach, namely, mechanical alloying (for only 30 min) and a quick hot-pressing method. The hierarchical microstructure, including point defects (atomic scale), dislocations, and nanoprecipitates (nanoscale) as well as grain boundaries (microscale), strongly scatters phonons with comparable sizes without deterioration of carrier mobility. Because of the higher carrier concentration of nanostructured AgSbSe 2 than that of coarse-grain AgSbSe 2 , power factor can also be improved slightly after nanostructuring. Ca doping further optimizes the carrier concentration and creates the point-defect scattering of phonons, leading to the ultralow lattice thermal conductivity ∼0.27 W m -1 K -1 at 673 K and thus largely improving the peak ZT up to 1.2. The high thermoelectric performance in combination with a facile fabrication method highlights AgSbSe 2 -based materials as robust thermoelectric candidates for energy harvesting.

The successful incorporation of Ag into single grain, Y-Ba-Cu-O bulk superconductors

NASA Astrophysics Data System (ADS)

Congreve, Jasmin V. J.; Shi, Yunhua; Dennis, Anthony R.; Durrell, John H.; Cardwell, David A.

2018-07-01

The use of RE-Ba-Cu-O [(RE)BCO] bulk superconductors, where RE = Y, Gd, Sm, in practical applications is, at least in part, limited by their mechanical properties and brittle nature, in particular. Alloying these materials with silver, however, produces a significant improvement in strength without any detrimental impact on their superconducting properties. Unfortunately, the top seeded melt growth technique, used routinely to process bulk (RE)BCO superconductors in the form of large, single grains required for practical applications, is complex and has a large number of inter-related variables, so the addition of silver increases the complexity of the growth process even further. This can make successful growth of this system extremely challenging. Here we report measurements of the growth rate of YBCO-Ag fabricated using a new growth technique consisting of continuous cooling and isothermal hold process. The resulting data form the basis of a model that has been used to derive suitable heating profiles for the successful single grain growth of YBCO-Ag bulk superconductors of up to 26 mm in diameter. The microstructure and distribution of silver within these samples have been studied in detail. The maximum trapped field at the top surface of the bulk YBCO-Ag samples has been found to be comparable to that of standard YBCO processed without Ag. The YBCO-Ag samples also exhibit a much more uniform trapped field profile compared to that of YBCO.

Cholinesterase (ChE) response and related mortality among birds fed ChE inhibitors

USGS Publications Warehouse

Ludke, J.L.; Hill, E.F.; Dieter, M.P.

1975-01-01

Patterns of mortality and inhibition of brain and plasma ChE in birds treated with ChE inhibitors were studied in an attempt to determine the validity of using ChE activity as a monitoring and diagnostic technique. Analysis of brain ChE activity proved to be reliable for diagnosing and monitoring effects of selected ChE inhibitors in birds. Brain ChE inhibition exceeding 20% indicated exposure, and inhibition greater than 50% was sufficient for diagnosing cause of death. Individuals that died from dietary exposure to parathion or carbofuran had brain ChE activities below 55% of normal; although individuals could survive with brain ChE activity lower than 50%. Problems associated with collection, storage, and analysis of tissues for ChE activity are discussed.

Comparative Study of Antimicrobial Activity of AgBr and Ag Nanoparticles (NPs)

PubMed Central

Suchomel, Petr; Kvitek, Libor; Panacek, Ales; Prucek, Robert; Hrbac, Jan; Vecerova, Renata; Zboril, Radek

2015-01-01

The diverse mechanism of antimicrobial activity of Ag and AgBr nanoparticles against gram-positive and gram-negative bacteria and also against several strains of candida was explored in this study. The AgBr nanoparticles (NPs) were prepared by simple precipitation of silver nitrate by potassium bromide in the presence of stabilizing polymers. The used polymers (PEG, PVP, PVA, and HEC) influence significantly the size of the prepared AgBr NPs dependently on the mode of interaction of polymer with Ag+ ions. Small NPs (diameter of about 60–70 nm) were formed in the presence of the polymer with low interaction as are PEG and HEC, the polymers which interact with Ag+ strongly produce nearly two times bigger NPs (120–130 nm). The prepared AgBr NPs were transformed to Ag NPs by the reduction using NaBH4. The sizes of the produced Ag NPs followed the same trends – the smallest NPs were produced in the presence of PEG and HEC polymers. Prepared AgBr and Ag NPs dispersions were tested for their biological activity. The obtained results of antimicrobial activity of AgBr and Ag NPs are discussed in terms of possible mechanism of the action of these NPs against tested microbial strains. The AgBr NPs are more effective against gram-negative bacteria and tested yeast strains while Ag NPs show the best antibacterial action against gram-positive bacteria strains. PMID:25781988

Ag/MnO₂ Nanorod as Electrode Material for High-Performance Electrochemical Supercapacitors.

PubMed

Guo, Zengcai; Guan, Yuming; Dai, Chengxiang; Mu, Jingbo; Che, Hongwei; Wang, Guangshuo; Zhang, Xiaoliang; Zhang, Zhixiao; Zhang, Xiliang

2018-07-01

A one-dimensional hierarchical Ag nanoparticle (AgNP)/MnO2 nanorod (MND) nanocomposite was synthesized by combining a simple solvothermal method and a facile reduction approach in situ. Owing to its high electrical conductivity, the resulting AgNP/MND nanocomposite displayed a high specific capacitance of 314 F g-1 at a current density of 2 A g-1, which was much higher than that of pure MNDs (178 F g-1). Resistances of the electrolyte (Rs) and charge transportation (Rct) of the nanocomposite were much lower than that of pure MNDs. Moreover, the nanocomposite exhibited outstanding long-term cycling ability (9% loss of initial capacity after 1000 cycles). These results indicated that the nanocomposite could serve as a promising and useful electrode material for future energy-storage applications.

Ice chemistry of acetaldehyde reveals competitive reactions in the first step of the Strecker synthesis of alanine: formation of HO-CH(CH3)-NH2 vs. HO-CH(CH3)-CN

NASA Astrophysics Data System (ADS)

Fresneau, Aurélien; Danger, Grégoire; Rimola, Albert; Duvernay, Fabrice; Theulé, Patrice; Chiavassa, Thierry

2015-08-01

The understanding of compound formation in laboratory simulated astrophysical environments is an important challenge in obtaining information on the chemistry occurring in these environments. We here investigate by means of both laboratory experiments and quantum chemical calculations the ice-based reactivity of acetaldehyde (CH3CHO) with ammonia (NH3) and hydrogen cyanide (HCN) in excess of water (H2O) promoted by temperature. A priori, this study should give information on alanine (2HN-CH(CH3)-COOH) formation (the simplest chiral amino acid detected in meteorites), since these reactions concern the first steps of its formation through the Strecker synthesis. However, infrared spectroscopy, mass spectrometry with HC14N or HC15N isotopologues and B3LYP-D3 results converge to indicate that an H2O-dominated ice containing CH3CHO, NH3 and HCN not only leads to the formation of α-aminoethanol (2HN-CH(CH3)-OH, the product compound of the first step of the Strecker mechanism) and its related polymers (2HN-(CH(CH3)-O)n-H) due to reaction between CH3CHO and NH3, but also to the 2-hydroxypropionitrile (HO­-CH(CH3)-CN) and its related polymers (H-(O-CH(CH3))n-CN) from direct reaction between CH3CHO and HCN. The ratio between these two species depends on the initial NH3/HCN ratio in the ice. Formation of α-aminoethanol is favoured when the NH3 concentration is larger than HCN. We also show that the presence of water is essential for the formation of HO­-CH(CH3)-CN, contrarily to 2HN-CH(CH3)-OH whose formation also takes place in absence of H2O ice. As in astrophysical ices NH3 is more abundant than HCN, formation of α-aminoethanol should consequently be favoured compared to 2-hydroxypropionitrile, thus pointing out α-aminoethanol as a plausible intermediate species for alanine synthesis through the Strecker mechanism in astrophysical ices.

Soil CO2, CH4 and N2O effluxes and concentrations in soil profiles down to 15.5m depth in eucalypt plantations under contrasted rainfall regimes

NASA Astrophysics Data System (ADS)

Germon, A.; Nouvellon, Y.; Christophe, J.; Chapuis-Lardy, L.; Robin, A.; Rosolem, C. A.; Gonçalves, J. L. D. M.; Guerrini, I. A.; Laclau, J. P.

2017-12-01

Silvicultural practices in planted forests affect the fluxes of greenhouse gases at the soil surface and the major factors driving greenhouse gas production in forest soils (substrate supply, temperature, water content,…) vary with soil depth. Our study aimed to assess the consequences of drought on the temporal variability of CO2, CH4 and N2O fluxes throughout very deep soil profiles in Eucalyptus grandis plantations 3 months before the harvest then in coppice, the first 18 months after clear-cutting. Two treatments were compared: one with 37% of throughfall excluded by plastic sheets (TE), and one without rainfall exclusion (WE). Measurements of soil CO2 efflux were made every two weeks for 30 months using a closed-path Li8100 system in both treatment. Every two weeks for 21 months, CO2, CH4 and N2O surface effluxes were measured using the closed-chamber method and concentrations in the soil were measured at 7 depths down to 15.5 m in both TE and WE. At most measurement dates, soil CO2 efflux were significantly higher in TE than in WE. Across the two treatments and the measurement dates, CO2 concentrations increased from 4446 ± 2188 ppm at 10 cm deep to 15622 ± 3523 ppm at 15.5 m, CH4 concentrations increased from 0.41 ± 0.17 ppm at 10 cm deep to 0.77 ± 0.24 ppm at 15.5 m and N2O concentrations remained roughly constant and were on average 478 ± 55 ppb between soil surface and 15.5 m deep. CO2 and N2O concentrations were on average 20.7 and 7.6% lower in TE than in WE, respectively, across the sampling depths. However, CH4 concentrations in TE were on average 44.4% higher than in WE, throughout the soil profile. Those results suggest that extended drought periods might reduce the production of CO2 and N2O but increase the accumulation of CH4 in eucalypt plantations established in deep tropical soils. Very deep tropical soils cover huge areas worldwide and improving our understanding of the spatiotemporal dynamics of gas concentrations in deep soil layers

Characterization of the intermediate-range order in new superionic conducting AgI-Ag2S-AgPO3 glasses by neutron diffraction

NASA Astrophysics Data System (ADS)

Kartini, E.; Kennedy, S. J.; Itoh, K.; Fukunaga, T.; Suminta, S.; Kamiyama, T.

Superionic conducting glasses are of considerable technological interest because of their use in batteries, sensors, and displays. We have investigated the new ternary systems AgI-Ag2S-AgPO3 where the ratio AgI:Ag2S is 1:1. The system (AgI)x(Ag2S)x(AgPO3)1-2x, for a AgI+Ag2S fraction less than 82mol%, yields glasses. We have used a neutron-diffraction technique to obtain the total scattering structure factor S(Q) of this system at room temperature by using the HIT spectrometer at the High Energy Accelerator (KEK), Tsukuba, Japan. As for AgI-AgPO3 glasses, S(Q) shows a peak at anomalously low Q in the range from 0.6 to 0.9 Å-1. This peak is not observed in the corresponding glass Ag2S-AgPO3 or pure AgPO3. The peak depends strongly on the dopant salt. Its intensity increases as the amount of (AgI+Ag2S) increases and its position shifts to lower Q, while the number density of the glasses decreases with x. This peak can be associated with an intermediate structure of particles lying inside a continuous host with the characteristic length between 5 and 10 Å [1].

AgS2O6CF3: the first trifluoromethylsulfonylsulfate(VI).

PubMed

Malinowski, Przemysław J; Derzsi, Mariana; Grochala, Wojciech

2013-08-07

We describe the synthetic route towards a novel class of salts, trifluoromethylsulfonylsulfates, as exemplified by the silver(I) derivative (AgS2O6CF3). Formation proceeds via direct reaction between a triflate precursor, AgSO3CF3, and SO3. The title compound crystallizes in the P2(1)/c unit cell with a = 5.15746(14) Å, b = 25.8563(9) Å, c = 5.53970(14) Å and β = 101.1749(19)°. The structure is layered with the puckered [AgS2O6] 2D sheets; the terminal CF3 groups are separated by the van der Waals gap, as seen also for related metal triflates. The compound is very fragile thermally and it decomposes endothermally to AgSO3CF3 with concomitant evolution of SO3 even at 65 °C or upon grinding in an agate mortar; thus it may serve as a solid store of--otherwise volatile and corrosive--SO3. The IR and Raman spectra of AgS2O6CF3 have been tentatively assigned based on similarities to those of related Ag2S2O7 and AgSO3CF3 and phonon calculations. Synthesis and properties of KS2O6CF3 are also briefly described.

New superhindered polydentate polyphosphine ligands P(CH2CH2P(t)Bu2)3, PhP(CH2CH2P(t)Bu2)2, P(CH2CH2CH2P(t)Bu2)3, and their ruthenium(II) chloride complexes.

PubMed

Gilbert-Wilson, Ryan; Field, Leslie D; Bhadbhade, Mohan M

2012-03-05

The synthesis and characterization of the extremely hindered phosphine ligands, P(CH(2)CH(2)P(t)Bu(2))(3) (P(2)P(3)(tBu), 1), PhP(CH(2)CH(2)P(t)Bu(2))(2) (PhP(2)P(2)(tBu), 2), and P(CH(2)CH(2)CH(2)P(t)Bu(2))(3) (P(3)P(3)(tBu), 3) are reported, along with the synthesis and characterization of ruthenium chloro complexes RuCl(2)(P(2)P(3)(tBu)) (4), RuCl(2)(PhP(2)P(2)(tBu)) (5), and RuCl(2)(P(3)P(3)(tBu)) (6). The bulky P(2)P(3)(tBu) (1) and P(3)P(3)(tBu) (3) ligands are the most sterically encumbered PP(3)-type ligands so far synthesized, and in all cases, only three phosphorus donors are able to bind to the metal center. Complexes RuCl(2)(PhP(2)P(2)(tBu)) (5) and RuCl(2)(P(3)P(3)(tBu)) (6) were characterized by crystallography. Low temperature solution and solid state (31)P{(1)H} NMR were used to demonstrate that the structure of RuCl(2)(P(2)P(3)(tBu)) (4) is probably analogous to that of RuCl(2)(PhP(2)P(2)(tBu)) (5) which had been structurally characterized.

Monovalent Cation Doping of CH3NH3PbI3 for Efficient Perovskite Solar Cells.

PubMed

Abdi-Jalebi, Mojtaba; Dar, M Ibrahim; Sadhanala, Aditya; Senanayak, Satyaprasad P; Grätzel, Michael; Friend, Richard H

2017-03-19

Here, we demonstrate the incorporation of monovalent cation additives into CH3NH3PbI3 perovskite in order to adjust the optical, excitonic, and electrical properties. The possibility of doping was investigated by adding monovalent cation halides with similar ionic radii to Pb 2+ , including Cu + , Na + , and Ag + . A shift in the Fermi level and a remarkable decrease of sub-bandgap optical absorption, along with a lower energetic disorder in the perovskite, was achieved. An order-of-magnitude enhancement in the bulk hole mobility and a significant reduction of transport activation energy within an additive-based perovskite device was attained. The confluence of the aforementioned improved properties in the presence of these cations led to an enhancement in the photovoltaic parameters of the perovskite solar cell. An increase of 70 mV in open circuit voltage for AgI and a 2 mA/cm 2 improvement in photocurrent density for NaI- and CuBr-based solar cells were achieved compared to the pristine device. Our work paves the way for further improvements in the optoelectronic quality of CH3NH3PbI3 perovskite and subsequent devices. It highlights a new avenue for investigations on the role of dopant impurities in crystallization and controls the electronic defect density in perovskite structures.

Monovalent Cation Doping of CH3NH3PbI3 for Efficient Perovskite Solar Cells

PubMed Central

Abdi-Jalebi, Mojtaba; Dar, M. Ibrahim; Sadhanala, Aditya; Senanayak, Satyaprasad P.; Grätzel, Michael; Friend, Richard H.

2017-01-01

Here, we demonstrate the incorporation of monovalent cation additives into CH3NH3PbI3 perovskite in order to adjust the optical, excitonic, and electrical properties. The possibility of doping was investigated by adding monovalent cation halides with similar ionic radii to Pb2+, including Cu+, Na+, and Ag+. A shift in the Fermi level and a remarkable decrease of sub-bandgap optical absorption, along with a lower energetic disorder in the perovskite, was achieved. An order-of-magnitude enhancement in the bulk hole mobility and a significant reduction of transport activation energy within an additive-based perovskite device was attained. The confluence of the aforementioned improved properties in the presence of these cations led to an enhancement in the photovoltaic parameters of the perovskite solar cell. An increase of 70 mV in open circuit voltage for AgI and a 2 mA/cm2 improvement in photocurrent density for NaI- and CuBr-based solar cells were achieved compared to the pristine device. Our work paves the way for further improvements in the optoelectronic quality of CH3NH3PbI3 perovskite and subsequent devices. It highlights a new avenue for investigations on the role of dopant impurities in crystallization and controls the electronic defect density in perovskite structures. PMID:28362369

AirCore-HR: a high-resolution column sampling to enhance the vertical description of CH4 and CO2

NASA Astrophysics Data System (ADS)

Membrive, Olivier; Crevoisier, Cyril; Sweeney, Colm; Danis, François; Hertzog, Albert; Engel, Andreas; Bönisch, Harald; Picon, Laurence

2017-06-01

An original and innovative sampling system called AirCore was presented by NOAA in 2010 Karion et al.(2010). It consists of a long ( > 100 m) and narrow ( < 1 cm) stainless steel tube that can retain a profile of atmospheric air. The captured air sample has then to be analyzed with a gas analyzer for trace mole fraction. In this study, we introduce a new AirCore aiming to improve resolution along the vertical with the objectives to (i) better capture the vertical distribution of CO2 and CH4, (ii) provide a tool to compare AirCores and validate the estimated vertical resolution achieved by AirCores. This (high-resolution) AirCore-HR consists of a 300 m tube, combining 200 m of 0.125 in. (3.175 mm) tube and a 100 m of 0.25 in. (6.35 mm) tube. This new configuration allows us to achieve a vertical resolution of 300 m up to 15 km and better than 500 m up to 22 km (if analysis of the retained sample is performed within 3 h). The AirCore-HR was flown for the first time during the annual StratoScience campaign from CNES in August 2014 from Timmins (Ontario, Canada). High-resolution vertical profiles of CO2 and CH4 up to 25 km were successfully retrieved. These profiles revealed well-defined transport structures in the troposphere (also seen in CAMS-ECMWF high-resolution forecasts of CO2 and CH4 profiles) and captured the decrease of CO2 and CH4 in the stratosphere. The multi-instrument gondola also carried two other low-resolution AirCore-GUF that allowed us to perform direct comparisons and study the underlying processing method used to convert the sample of air to greenhouse gases vertical profiles. In particular, degrading the AirCore-HR derived profiles to the low resolution of AirCore-GUF yields an excellent match between both sets of CH4 profiles and shows a good consistency in terms of vertical structures. This fully validates the theoretical vertical resolution achievable by AirCores. Concerning CO2 although a good agreement is found in terms of vertical structure

Preparation of Ag superhydrophobic surface on metal substrates

NASA Astrophysics Data System (ADS)

Li, J. Y.; Lu, S. X.; Xu, W. G.; Duan, Y. Q.; Yang, X. C.; Cheng, Y. Y.; He, G.; Cui, S.

2018-01-01

In this work, the facile approaches are developed for preparation the Ag superhydrophobic surfaces (SHSs) on zinc (Zn), copper (Cu) and aluminium (Al) substrates. The water contact angles (WCAs) of the Ag SHSs on Zn, Cu and Al substrates are 167°, 165° and 154°, respectively. Furthermore, the water sliding angle (WSA) of each surface is less than 1°. The morphology and chemical composition of the samples are characterized using scanning electron microscopy (SEM) and X-ray diffraction pattern (XRD). The as-prepared three kinds of SHSs possess the self-cleaning performance, which can quickly take the chalk away when the water droplets fall down the SHSs. In addition, the superhydrophobicity of the SHSs can well maintain after exposure to the air for 6 months, indicating that the surfaces can sustain good stability.

Direct C-H alkylation and indole formation of anilines with diazo compounds under rhodium catalysis.

PubMed

Mishra, Neeraj Kumar; Choi, Miji; Jo, Hyeim; Oh, Yongguk; Sharma, Satyasheel; Han, Sang Hoon; Jeong, Taejoo; Han, Sangil; Lee, Seok-Yong; Kim, In Su

2015-12-18

The rhodium(III)-catalyzed direct functionalization of aniline C-H bonds with α-diazo compounds is described. These transformations provide a facile construction of ortho-alkylated anilines with diazo malonates or highly substituted indoles with diazo acetoacetates.

ChIA-PET2: a versatile and flexible pipeline for ChIA-PET data analysis

PubMed Central

Li, Guipeng; Chen, Yang; Snyder, Michael P.; Zhang, Michael Q.

2017-01-01

ChIA-PET2 is a versatile and flexible pipeline for analyzing different types of ChIA-PET data from raw sequencing reads to chromatin loops. ChIA-PET2 integrates all steps required for ChIA-PET data analysis, including linker trimming, read alignment, duplicate removal, peak calling and chromatin loop calling. It supports different kinds of ChIA-PET data generated from different ChIA-PET protocols and also provides quality controls for different steps of ChIA-PET analysis. In addition, ChIA-PET2 can use phased genotype data to call allele-specific chromatin interactions. We applied ChIA-PET2 to different ChIA-PET datasets, demonstrating its significantly improved performance as well as its ability to easily process ChIA-PET raw data. ChIA-PET2 is available at https://github.com/GuipengLi/ChIA-PET2. PMID:27625391

Quasi-Instantaneous Bacterial Inactivation on Cu-Ag Nanoparticulate 3D Catheters in the Dark and Under Light: Mechanism and Dynamics.

PubMed

Rtimi, Sami; Sanjines, Rosendo; Pulgarin, Cesar; Kiwi, John

2016-01-13

The first evidence for Cu-Ag (50%/50%) nanoparticulate hybrid coatings is presented leading to a complete and almost instantaneous bacterial inactivation in the dark (≤5 min). Dark bacterial inactivation times on Cu-Ag (50%/50%) were observed to coincide with the times required by actinic light irradiation. This provides the evidence that the bimetal Cu-Ag driven inactivation predominates over a CuO/Cu2O and Ag2O oxides inducing a semiconductor driven behavior. Cu- or Ag-coated polyurethane (PU) catheters led to bacterial inactivation needing about ∼30 min. The accelerated bacterial inactivation by Cu-Ag coated on 3D catheters sputtered was investigated in a detailed way. The release of Cu/Ag ions during bacterial inactivation was followed by inductively coupled plasma mass-spectrometry (ICP-MS) and the amount of Cu and Ag-ions released were below the cytotoxicity levels permitted by the sanitary regulations. By stereomicroscopy the amount of live/dead cells were followed during the bacterial inactivation time. By Fourier transform infrared spectroscopy (FTIR), the systematic shift of the -(CH2) band stretching of the outer lipo-polysaccharide bilayer (LPS) was followed to monitor the changes leading to cell lysis. A hydrophobic to hydrophilic transformation of the Cu-Ag PU catheter surface under light was observed within 30 min followed concomitantly to a longer back transformation to the hydrophobic initial state in the dark. Physical insight is provided for the superior performance of Cu-Ag films compared to Cu or Ag films in view of the drastic acceleration of the bacterial inactivation observed on bimetal Cu-Ag films coating PU catheters. A mechanism of bacterial inactivation is suggested that is consistent with the findings reported in this study.

Photochemical Modeling of CH3 Abundances in the Outer Solar System

NASA Technical Reports Server (NTRS)

Lee, Anthony Y. T.; Yung, Yuk L.; Moses, Julianne

2000-01-01

Recent measurements of methyl radicals (CH3) in the upper atmospheres of Saturn and Neptune by the Infrared Space Observatory (ISO) provide new constraints to photochemical models of hydrocarbon chemistry in the outer solar system. The derived column abundances of CH3 on Saturn above 10 mbar and Neptune above the 0.2 mbar pressure level are (2.5 - 6.0) x 10(exp 13) / sq cm and (0.7 - 2.8) x 10(exp 13) / sq cm, respectively. We use the updated Caltech/Jet Propulsion Laboratory photochemical model, which incorporates hydrocarbon photochemistry, vertical molecular and bulk atmospheric eddy diffusion, and realistic radiative transfer modeling, to study the CH3 abundances in the upper atmosphere of the giant planets and Titan. We identify the key reactions that control the concentrations of CH3 in the model, such as the three-body recombination reaction, CH3 + CH3 + M yields C2H6 + M. We evaluate and extrapolate the three-body rate constant of this reaction to the low-temperature limit (1.8 x 10(exp -16) T(sup -3.75) e(sup -300/T), T < 300 K) and compare methyl radical abundances in five atmospheres: Jupiter, Saturn, Uranus, Neptune, and Titan. The sensitivity of our models to the rate coefficients for the reactions H + CH3 + M yields CH4 + M, H + C2H3 yields C2H2 + H2, (sup 1)CH2 + H2 yields CH3 + H, and H + C2H5 yields 2CH3, the branching ratios of CH4 photolysis, vertical mixing in the five atmospheres, and Lyman alpha photon enhancement at the orbit of Neptune have all been tested. The results of our model CH3 abundances for both Saturn (5.1 x 10(exp 13) / sq cm) and Neptune (2.2 x 10(exp 13) / sq cm) show good agreement with ISO Short Wavelength Spectrometer measurements. Using the same chemical reaction set, our calculations also successfully generate vertical profiles of stable hydrocarbons consistent with Voyager and ground-based measurements in these outer solar system atmospheres. Predictions of CH3 column concentrations (for p <= 0.2 mbar) in the atmospheres

Co-processing CH4 and oxygenates on Mo/H-ZSM-5: 2. CH4-CO2 and CH4-HCOOH mixtures.

PubMed

Bedard, Jeremy; Hong, Do-Young; Bhan, Aditya

2013-08-07

Co-processing of formic acid or carbon dioxide with CH4 (FA/CH4 = 0.01-0.03 and CO2/CH4 = 0.01-0.03) on Mo/H-ZSM-5 catalysts at 950 K with the prospect of kinetically coupling dehydrogenation and deoxygenation cycles results instead in a two-zone, staged bed reactor configuration consisting of upstream oxygenate/CH4 reforming and downstream CH4 dehydroaromatization. The addition of an oxygenate co-feed (oxygenate/CH4 = 0.01-0.03) causes oxidation of the active molybdenum carbide catalyst while producing CO and H2 until completely converted. Forward rates of C6H6 synthesis are unaffected by the introduction of an oxygenate co-feed after rigorously accounting for the thermodynamic reversibility caused by the H2 produced in oxygenate reforming reactions and the fraction of the active catalyst deemed unavailable for CH4 DHA. All effects of co-processing oxygenates with CH4 can be construed in terms of an approach to equilibrium.

Genome-wide profiling of DNA-binding proteins using barcode-based multiplex Solexa sequencing.

PubMed

Raghav, Sunil Kumar; Deplancke, Bart

2012-01-01

Chromatin immunoprecipitation (ChIP) is a commonly used technique to detect the in vivo binding of proteins to DNA. ChIP is now routinely paired to microarray analysis (ChIP-chip) or next-generation sequencing (ChIP-Seq) to profile the DNA occupancy of proteins of interest on a genome-wide level. Because ChIP-chip introduces several biases, most notably due to the use of a fixed number of probes, ChIP-Seq has quickly become the method of choice as, depending on the sequencing depth, it is more sensitive, quantitative, and provides a greater binding site location resolution. With the ever increasing number of reads that can be generated per sequencing run, it has now become possible to analyze several samples simultaneously while maintaining sufficient sequence coverage, thus significantly reducing the cost per ChIP-Seq experiment. In this chapter, we provide a step-by-step guide on how to perform multiplexed ChIP-Seq analyses. As a proof-of-concept, we focus on the genome-wide profiling of RNA Polymerase II as measuring its DNA occupancy at different stages of any biological process can provide insights into the gene regulatory mechanisms involved. However, the protocol can also be used to perform multiplexed ChIP-Seq analyses of other DNA-binding proteins such as chromatin modifiers and transcription factors.

Measurements of methane emissions from natural gas gathering facilities and processing plants: measurement methods

DOE PAGES

Roscioli, J. R.; Yacovitch, T. I.; Floerchinger, C.; ...

2015-05-07

Increased natural gas production in recent years has spurred intense interest in methane (CH 4) emissions associated with its production, gathering, processing, transmission, and distribution. Gathering and processing facilities (G&P facilities) are unique in that the wide range of gas sources (shale, coal-bed, tight gas, conventional, etc.) results in a wide range of gas compositions, which in turn requires an array of technologies to prepare the gas for pipeline transmission and distribution. We present an overview and detailed description of the measurement method and analysis approach used during a 20-week field campaign studying CH 4 emissions from the natural gasmore » G&P facilities between October 2013 and April 2014. Dual-tracer flux measurements and on-site observations were used to address the magnitude and origins of CH 4 emissions from these facilities. The use of a second tracer as an internal standard revealed plume-specific uncertainties in the measured emission rates of 20–47%, depending upon plume classification. Furthermore, combining downwind methane, ethane (C 2H 6), carbon monoxide (CO), carbon dioxide (CO 2), and tracer gas measurements with on-site tracer gas release allows for quantification of facility emissions and in some cases a more detailed picture of source locations.« less

Enhanced ethylene photodegradation performance of g-C3N4-Ag3PO4 composites with direct Z-scheme configuration.

PubMed

Chen, Xuxing; Huang, Xintang; Yi, Zhiguo

2014-12-22

Photocatalytic oxidation of ethylene continues to be a challenge at the frontier of chemistry. In a previous report, a simple Ag3 PO4 semiconductor material was shown to have strong photooxidative properties and efficiently oxidised water and decomposed organics in aqueous solution under visible-light illumination. Herein, its effects on the photo-oxidation of gaseous C2 H4 were investigated by fabricating graphitic C3 N4-Ag3 PO4 composite semiconductors with direct Z-scheme configuration. It was found that both the ethylene photo-oxidative activity and the stability of Ag3 PO4 are considerably improved by fabrication of Z-scheme composites. Moreover, stable C2 H4 photo-oxidation activity could be obtained by treating the composite at 450 °C for 3 h after long-term operation. From the point of view of environmental pollutant cleanup, the present technique avoids the side reaction of oxidising water and will be valuable for further investigations on both Ag3 PO4 and CH degradation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A variable Ag-Cr-Oxalate channel lattice: [M(x)Ag(0.5)(-)(x)(H(2)O)(3)]@[Ag(2.5)Cr(C(2)O(4))(3)], M = K, Cs, Ag.

PubMed

Dean, Philip A W; Craig, Don; Dance, Ian; Russell, Vanessa; Scudder, Marcia

2004-01-26

Reaction of aqueous AgNO(3) with aqueous M(3)[Cr(ox)(3)] in >or=3:1 molar ratio causes the rapid growth of large, cherry-black, light-stable crystals which are not Ag(3)[Cr(ox)(3)], but [M(0.5)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)] (ox(2)(-) = oxalate, C(2)O(4)(2)(-); M = Na, K, Cs, Ag, or mixtures of Ag and a group 1 element). The structure of these crystals contains an invariant channeled framework, with composition [[Ag(2.5)Cr(ox)(3)](-)(0.5)]( infinity ), constructed with [Cr(ox)(3)] coordination units linked by Ag atoms through centrosymmetric [Cr-O(2)C(2)O(2)-Ag](2) double bridges. The framework composition [Ag(2.5)Cr(ox)(3)](-)(0.5) occurs because one Ag is located on a 2-fold axis. Within the channels there is a well-defined and ordered set of six water molecules, strongly hydrogen bonded to each other and some of the oxalate O atoms. This invariant channel plus water structure accommodates group 1 cations, and/or Ag cations, in different locations and in variable proportions, but always coordinated by channel water and some oxalate O atoms. The general formulation of these crystals is therefore [M(x)Ag(0.5-x)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)]. Five different crystals with this structure are reported, with compositions 1 Ag(0.5)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 2 Cs(0.19)Ag(0.31)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 3 K(0.28)Ag(0.22)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 4 Cs(0.41)Ag(0.09)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), and 5 Cs(0.43)Ag(0.07) [Ag(2.5)Cr(ox)(3)](H(2)O)(3). All crystallize in space group C2/c, with a approximately 18.4, b approximately 14.6, c approximately 12.3 A, beta approximately 113 degrees. Pure Ag(3)[Cr(ox)(3)](H(2)O)(3), which has the same crystal structure (1), was obtained from water by treating Li(3)[Cr(ox)(3)] with excess AgNO(3). Complete dehydration of all of these compounds occurs between 30 and 100 degrees C, with loss of diffraction, but rehydration by exposure to H(2)O(g) at ambient temperature leads to recovery of the original diffraction pattern. In single

RRR and thermal conductivity of Ag and Ag0.2wt%Mg alloy in Ag/Bi-2212 wires

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

Li, Pei; Ye, L.; Jiang. J., Jiang. J.

The residual resistivity ratio (RRR) and thermal conductivity of metal matrix in metal/superconductor composite wires are important parameters for designing superconducting magnets. However, the resistivity of silver in reacted Ag/Bi-2212 wires has yet to be determined over temperature range from 4.2 K to 80 K because Bi-2212 filaments have a critical transition temperature Tc of ~ 80 K, and because it is unknown whether the RRR of Ag/Bi-2212 degrades with Cu diffusing from Bi-2212 filaments into silver sheathes at elevated temperatures and to what degree it varies with heat treatment. We measured the resistivity of stand-alone Ag and AgMg (Ag-0.2wt%Mg)more » wires as well as the resistivity of Ag and Ag- 0.2wt%Mg in the state-of-the-art Ag/Bi-2212 round wires reacted in 1 bar oxygen at 890 °C for 1, 8, 24 and 48 hours and quickly cooled to room temperature. The heat treatment was designed to reduce the critical current Ic of Bi-2212 wires to nearly zero while allowing Cu loss to fully manifest itself. We determined that pure silver exhibits a RRR of ~ 220 while the oxide-dispersion strengthened AgMg exhibits a RRR of ~ 5 in stand-alone samples. A surprising result is that the RRR of silver in the composite round wires doesn’t degrade with extended time at 890 °C for up to 48 hours. This surprising result may be explained by our observation that the Cu that diffuses into the silver tends to form Cu2O precipitates in oxidizing atmosphere, instead of forming Ag-Cu solution alloy. We also measured the thermal conductivity and the magneto-resistivity of pure Ag and Ag-0.2 wt%Mg from 4.2 K to 300 K in magnetic fields up to 14.8 T and summarized them using a Kohler plot.« less

Effects of UV/Ag-TiO2/O3 advanced oxidation on unicellular green alga Dunaliella salina: implications for removal of invasive species from ballast water.

PubMed

Wu, Donghai; You, Hong; Du, Jiaxuan; Chen, Chuan; Jin, Darui

2011-01-01

The UV/Ag-TiO2/O3 process was investigated for ballast water treatment using Dunaliella salina as an indicator. Inactivation curves were obtained, and the toxicity of effluent was determined. Compared with individual unit processes using ozone or UV/Ag-TiO2, the inactivation efficiency of D. salina by the combined UV/Ag-TiO2/O3 process was enhanced. The presence of ozone caused an immediate decrease in chlorophyll a (chl-a) concentration. Inactivation efficiency and ch1-a removal efficiency were positively correlated with ozone dose and ultraviolet intensity. The initial total residual oxidant (TRO) concentration of effluent increased with increasing ozone dose, and persistence of TRO resulted in an extended period of toxicity. The results suggest that UV/Ag-TiO2/O3 has potential for ballast water treatment.

Band Structure Engineering of Cs2AgBiBr6 Perovskite through Order-Disordered Transition: A First-Principle Study.

PubMed

Yang, Jingxiu; Zhang, Peng; Wei, Su-Huai

2018-01-04

Cs 2 AgBiBr 6 was proposed as one of the inorganic, stable, and nontoxic replacements of the methylammonium lead halides (CH 3 NH 3 PbI 3 , which is currently considered as one of the most promising light-harvesting material for solar cells). However, the wide indirect band gap of Cs 2 AgBiBr 6 suggests that its application in photovoltaics is limited. Using the first-principle calculation, we show that by controlling the ordering parameter at the mixed sublattice, the band gap of Cs 2 AgBiBr 6 can vary continuously from a wide indirect band gap of 1.93 eV for the fully ordered double-perovskite structure to a small pseudodirect band gap of 0.44 eV for the fully random alloy. Therefore, one can achieve better light absorption simply by controlling the growth temperature and thus the ordering parameters and band gaps. We also show that controlled doping in Cs 2 AgBiBr 6 can change the energy difference between ordered and disordered Cs 2 AgBiBr 6 , thus providing further control of the ordering parameters and the band gaps. Our study, therefore, provides a novel approach to carry out band structure engineering in the mixed perovskites for optoelectronic applications.

Synthesis, characterization, and chiral properties of CoIII2AgI3 pentanuclear, CoIII4ZnII4 octanuclear, and CoIII mononuclear complexes with aza-capped hexadentate-N3S3 thiolate ligands: crystal structures of.

PubMed

Tokuda, K; Okamoto, K; Konno, T

2000-01-24

The reaction of an S-bridged Co2(III)Ag3(I) pentanuclear complex, [Ag3[Co(aet)3]2][BF4]3 (aet = NH2CH2CH2S-), with paraformaldehyde in basic acetonitrile, followed by adding aqueous ammonia, produced an aza-capped Co2(III)-Ag3(I) complex, [Ag3[Co(L)]2]3+ ([1]3+) (L = N(CH2NHCH2CH2S-)3). The crystal structure of [1]3+ was determined by X-ray crystallography. [1][PF6]3 x H2O, empirical formula C18H44Ag3Co2F18N8OP3S6, crystallizes in the tetragonal space group 142m with a = 13.012(1) A, c = 24.707(2) A, and Z = 4. In [1]3+ the two aza-capped [Co(L)] units are linked by three Ag(I) atoms, such that the two Co(III) atoms are encapsulated in a macrobicyclic metallocage, [Ag3(I)(L)2]3-. [1]3+ was converted to an aza-capped Co4(III)Zn4(II) octanuclear complex, [Zn4O[Co(L)]4]6+ ([2]6+), by reaction with I- in the presence of Zn2+ and ZnO in water. The crystal structure of [2]6+ was also determined by X-ray crystallography. [2][PF6]6 x 8H2O, empirical formula C36H100Co4F36N16O9P6S12Zn4, crystallizes in the monoclinic space group P2(1/n) with a = 14.33(7) A, b = 25.67(10) A, c = 24.83(6) A, beta = 101.3(3) degrees , and Z = 4. In [2]6+ each of four [Co(L)] units is bound to each trigonal Zn3(II) face of the tetrahedral [Zn4(II)O]6+ core, such that each Co(III) atom is encapsulated in a macrobicyclic [Zn4(II)O(L)] fragment. Treatment of [2]6+ with a basic aqueous solution resulted in a cleavage of the Zn-S bonds to produce an aza-capped Co(III) mononuclear complex, [Co(L)] ([3]), from which [1]3+ is readily reproduced by the reaction with Ag+ in water. All the reactions were found to proceed with retention of the absolute configuration (delta or lambda) of the Co(III) chiral centers; deltadelta-[1]3+, deltadeltadeltadelta-[2]6+, and A-[3] were derived from deltadelta-[Ag3[Co(aet)3]2]3+. The contributions to circular dichroism (CD) from the triple helicity in [1]3+, besides from the asymmetric N and S donor atoms and the Co(III) chiral centers in [1]3+ and [2]6+, were estimated

Synthesis of g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction with enhanced photocatalytic performance

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

He, Peizhi; Song, Limin; Zhang, Shujuan, E-mail: songlmnk@sohu.com

2014-03-01

Graphical abstract: g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst with visible-light response was prepared by a facile coprecipitation method. The results show that g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} possesses a much higher activity for the decomposition of RhB than that of the pure Ag{sub 3}PO{sub 4} particles. The most mechanism is that g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst can efficiently separate the photogenerated electron–hole pairs, enhancing the photocatalytic activity of g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} composites. - Highlights: • g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction showed much higher activity than that of Ag{sub 3}PO{sub 4}. • The high activitymore » could be attributed to g-C{sub 3}N{sub 4} for modifying Ag{sub 3}PO{sub 4}. • More ·OH radicals may be significant reason to improve Ag{sub 3}PO{sub 4} activity. - Abstract: g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst with visible-light response was prepared by a facile coprecipitation method. The photocatalysts were characterized by X-ray powder diffraction, transmission electron microscopy, UV–vis absorption spectroscopy and Fourier transform infrared spectroscopy. The photocatalytic activities of the obtained samples were tested by using Rhodamine B (RhB) as the degradation target under visible light irradiation. g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} decomposed RhB more effectively than the pure Ag{sub 3}PO{sub 4} particles did, and 2 wt.% g-C{sub 3}N{sub 4} had the highest activity. Furthermore, 2 wt.% g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} degraded high-concentration RhB more potently than unmodified Ag{sub 3}PO{sub 4} did, probably because g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst enhanced the photocatalytic activity by efficiently separating the photogenerated electron–hole pairs.« less

ChIP-re-ChIP: Co-occupancy Analysis by Sequential Chromatin Immunoprecipitation.

PubMed

Beischlag, Timothy V; Prefontaine, Gratien G; Hankinson, Oliver

2018-01-01

Chromatin immunoprecipitation (ChIP) exploits the specific interactions between DNA and DNA-associated proteins. It can be used to examine a wide range of experimental parameters. A number of proteins bound at the same genomic location can identify a multi-protein chromatin complex where several proteins work together to regulate gene transcription or chromatin configuration. In many instances, this can be achieved using sequential ChIP; or simply, ChIP-re-ChIP. Whether it is for the examination of specific transcriptional or epigenetic regulators, or for the identification of cistromes, the ability to perform a sequential ChIP adds a higher level of power and definition to these analyses. In this chapter, we describe a simple and reliable method for the sequential ChIP assay.

Anharmonic Effect in CH3CH2C(=O)OCH2CH3 Decomposition

NASA Astrophysics Data System (ADS)

Ding, Yang; Song, Liguo; Yao, Li; Xia, Wenwen

2017-12-01

In this paper, using the B3LYP functional and CCSD(T) method with 6-311++G** basis set, the harmonic and anharmonic rate constants in the unimolecular dissociation of ethyl propanoate have been calculated using Rice-Ramsperger-Kassel-Marcus theory. The anharmonic rate constants of the title reaction have also been examined, the comparison shows that, the anharmonic effect especially in the case of high total energies and temperature for channels 3 to 6 is significant, so that the anharmonic effect cannot be neglected for unimolecular dissociation reaction of CH3CH2C(=O)OCH2CH3 both in microcanonical and canonical systems.

An ab initio study of the low-lying doublet states of AgO and AgS

NASA Astrophysics Data System (ADS)

Bauschlicher, Charles W.; Partridge, Harry; Langhoff, Stephen R.

1990-11-01

Spectroscopic constants ( Do, re, μ e, Te) are determined for the doublet states of AgO and AgS below ≈ 30000 cm -1. valence basis sets are employed in conjunction with relativistic effective core potentials (RECPs). Electron correlation is included using the modified coupled-pair functional (MCPF) and multireferenceconfiguration interaction (MRCI) methods. The A 2Σ +-X 2Π band system is found to occur in the near infrared ( ≈ 9000 cm -1) and to be relatively weak with a radiative lifetime of 900 μs for A 2Σ + (ν = 0). The weakly bound C 2Π state (our notation), the upper state of the blue system, is found to require high levels of theoretical treatment to determine a quantitatively accurate potential. The red system is assigned as a transition from the C 2Π state to the previously unobserved A 2Σ + state. Several additional transitions are identified that should be detectable experiment A more limited study is performed for the vertical excitation spectrum of AgS. In addition, a detailed all-electron study of the X 2Π and A 2Σ + states of AgO is carried out using large atomic natural orbital (ANO) basis sets. Our best calculated Do value for AgO is significantly less than the experimental value, which suggests that there may be some systematic error in the experimental determination.

Antibacterial Ag/a-C nanocomposite coatings: The influence of nano-galvanic a-C and Ag couples on Ag ionization rates

NASA Astrophysics Data System (ADS)

Manninen, N. K.; Calderon, S.; Carvalho, I.; Henriques, M.; Cavaleiro, A.; Carvalho, S.

2016-07-01

Biofilm formation has been pointed as a major concern in different industrial applications, namely on biomedical implants and surgical instruments, which has prompted the development of new strategies for production of efficient antimicrobial surfaces. In this work, nano-galvanic couples were created to enhance the antibacterial properties of silver, by embedding it into amorphous carbon (a-C) matrix. The developed Ag/a-C nanocomposite coatings, deposited by magnetron sputtering, revealed an outstanding antibacterial activity against Staphylococcus epidermidis, promoting a total reduction in biofilm formation with no bacteria counts in all dilution. The open circuit potential (OCP) tests in 0.9% NaCl confirmed that a-C shows a positive OCP value, in contrast to Ag coating, thus enhancing the ionization of biocidal Ag+ due to the nano-galvanic couple activation. This result was confirmed by the inductively coupled plasma-optical emission spectroscopy (ICP-OES), which revealed a higher Ag ionization rate in the nanocomposite coating in comparison with the Ag coating. The surface of Ag/a-C and Ag coatings immersed in 0.9% NaCl were monitored by scanning electron microscopy (SEM) over a period of 24 h, being found that the Ag ionization determined by ICP-OES was accompanied by an Ag nanoparticles coalescence and agglomeration in Ag/a-C coating.

Half-Lives of 101Rh and 108m Ag

NASA Astrophysics Data System (ADS)

Norman, Eric; Browne, Edgardo; Shugart, Howard

2014-09-01

and 108mAg determined from these measurements. This work was supported in part by the U. S. Dept. of Energy under Contract Numbers DE-AC02-05CH11231 and DE-NA0000979.

Plasmon-resonance-enhanced visible-light photocatalytic activity of Ag quantum dots/TiO2 microspheres for methyl orange degradation

NASA Astrophysics Data System (ADS)

Yu, Xin; Shang, Liwei; Wang, Dongjun; An, Li; Li, Zhonghua; Liu, Jiawen; Shen, Jun

2018-06-01

We successfully prepared Ag quantum dots modified TiO2 microspheres by facile solvothermal and calcination method. The as-prepared Ag quantum dots/TiO2 microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The Ag quantum dots/TiO2 photocatalyst showed excellent visible light absorption and efficient photocatalytic activity for methyl orange degradation. And the sample with the molar ratio of 0.05 (Ag to Ti) showed the best visible light photocatalytic activity for methyl orange degradation, mainly because of the surface plasmon resonance (SPR) effects of Ag quantum dots to generate electron and hole pairs for enhanced visible light photocatalysis. Finally, possible visible light photocatalytic mechanism of Ag quantum dots/TiO2 microspheres for methyl orange degradation was proposed in detail.

Measuring the Distribution and Excitation of Cometary CH3OH Using ALMA

NASA Astrophysics Data System (ADS)

Cordiner, M. A.; Charnley, S. B.; Mumma, M. J.; Bockelée-Morvan, D.; Biver, N.; Villanueva, G.; Paganini, L.; Milam, S. N.; Remijan, A. J.; Lis, D. C.; Crovisier, J.; Boissier, J.; Kuan, Y.-J.; Coulson, I. M.

2016-10-01

The Atacama Large Millimeter/submillimeter Array (ALMA) was used to obtain measurements of spatially and spectrally resolved CH3OH emission from comet C/2012 K1 (PanSTARRS) on 28-29 June 2014. Detection of 12-14 emission lines of CH3OH on each day permitted the derivation of spatially-resolved rotational temperature profiles (averaged along the line of sight), for the innermost 5000 km of the coma. On each day, the CH3OH distribution was centrally peaked and approximately consistent with spherically symmetric, uniform outflow. The azimuthally-averaged CH3OH rotational temperature (T rot) as a function of sky-projected nucleocentric distance (ρ), fell by about 40 K between ρ= 0 and 2500 km on 28 June, whereas on 29 June, T rot fell by about 50 K between ρ =0 km and 1500 km. A remarkable (~50 K) rise in T rot at ρ = 1500-2500 km on 29 June was not present on 28 June. The observed variations in CH3OH rotational temperature are interpreted primarily as a result of variations in the coma kinetic temperature due to adiabatic cooling, and heating through Solar irradiation, but collisional and radiative non-LTE excitation processes also play a role.

Facile fabrication of large-grain CH 3NH 3PbI 3-xBr x films for high-efficiency solar cells via CH 3NH 3Br-selective Ostwald ripening

DOE PAGES

Yang, Mengjin; Zhang, Taiyang; Schulz, Philip; ...

2016-08-01

Organometallic halide perovskite solar cells (PSCs) have shown great promise as a low-cost, high-efficiency photovoltaic technology. Structural and electro-optical properties of the perovskite absorber layer are most critical to device operation characteristics. Here we present a facile fabrication of high-efficiency PSCs based on compact, large-grain, pinhole-free CH 3NH 3PbI 3-xBr x (MAPbI 3-xBr x) thin films with high reproducibility. A simple methylammonium bromide (MABr) treatment via spin-coating with a proper MABr concentration converts MAPbI 3 thin films with different initial film qualities (for example, grain size and pinholes) to high-quality MAPbI 3-xBr x thin films following an Ostwald ripening process,more » which is strongly affected by MABr concentration and is ineffective when replacing MABr with methylammonium iodide. A higher MABr concentration enhances I-Br anion exchange reaction, yielding poorer device performance. Lastly, this MABr-selective Ostwald ripening process improves cell efficiency but also enhances device stability and thus represents a simple, promising strategy for further improving PSC performance with higher reproducibility and reliability.« less

Visualizing Redox Dynamics of a Single Ag/AgCl Heterogeneous Nanocatalyst at Atomic Resolution

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

Wu, Yimin A.; Li, Liang; Li, Zheng

Operando characterization of gas solid reactions at the atomic scale is of great importance for determining the mechanism of catalysis. This is especially true in the study of heterostructures because of structural correlation between the different parts. However, such experiments are challenging and have rarely been accomplished. In this work, atomic scale redox dynamics of Ag/AgCl heterostructures have been studied using in situ environmental transmission electron microscopy (ETEM) in combination with density function theory (DFT) calculations. The reduction of Ag/AgCl to Ag is likely a result of the formation of Cl vacancies while Ag+ ions accept electrons. The oxidation processmore » of Ag/AgCl has been observed: rather than direct replacement of Cl by O, the Ag/AgCl nanocatalyst was first reduced to Ag, and then Ag was oxidized to different phases of silver oxide under different O-2 partial pressures. Ag2O formed at low O-2 partial pressure, whereas AgO formed at atmospheric pressure. By combining in situ ETEM observation and DFT calculations, this structural evolution is characterized in a distinct nanoscale environment.« less

Interesting electron storage phenomenon in the spherical Ag/TiO{sub 2} nanocomposites and its application for the decomposition of acetaldehyde in the dark

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

Wang, Xinyan; State Key Laboratory of Electroanalytical Chemistry, c/o Engineering Laboratory for Modern Analytical Techniques, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022; Wu, Tongshun

2016-01-15

Highlights: • The Ag/TiO{sub 2} composites have been prepared by a facile solvothermal method. • The photogenerated charges transfer behaviors between the Ag and TiO{sub 2}. • The Ag/TiO{sub 2} composites can store photogenerated electrons for a relative long time. • The Ag/TiO{sub 2} composite could be further used to decompose acetaldehyde in the dark. - Abstract: Ag/TiO{sub 2} nanocomposite has been prepared by a facile one-step low-temperature solvothermal method. The powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements have been used to characterize the detailed structure of the as-synthesized nanocomposite and the results indicate that the nanocompoistemore » is with the spherical structure and Ag and TiO{sub 2} nanoparticles are homogeneously dispersed in the sphere. Surface photovoltage (SPV) and transient photovoltage (TPV) techniques were used to further investigate the charge transfer behavior between the TiO{sub 2} and Ag in this composite material, and the results reveal that the nanocomposites could store the electrons for a relative long time even under air. Furthermore, these stored electrons in the nanocomposites have been successfully applied to decompose the acetaldehyde in the dark.« less

Enhancing the ag precipitation by surface mechanical attrition treatment on Cu-Ag alloys

NASA Astrophysics Data System (ADS)

Liu, Jiabin; Zhang, Lehao; Liu, Jingjing; Huang, Liuyi; Gu, Hao; Fang, Youtong; Meng, Liang; Zhang, Jian

2016-09-01

The influence of surface mechanical attrition treatment (SMAT) on Ag precipitation in Cu-Ag alloys was investigated. Cu-6 wt% Ag was melt, cold rolled and solution treated to be Cu-Ag solid solution, which was either aged at 250 and 350 °C for 24 h directly or SMAT-ed before aging. Ag precipitates were hard be found in the directly aged Cu-Ag sample while they were observed clearly in the SMAT-ed counterpart at 250 °C. The Ag precipitates formed in the surface layer by SMAT are much coarser than those in the un-SMAT-ed sample. It is obvious that the precipitating behavior of Ag was promoted significantly by SMAT approach. A large number of defects were generated by SMAT and they were acting as fast atomic diffusion channels that facilitated the atomic diffusion of Ag.

Luminescent Copper(I) Halide Butterfly Dimers Coordinated to [Au(CH3imCH2py)2]BF4 and [Au(CH3imCH2quin)2]BF4

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

Catalano, V.; Moore, A; Shearer, J

2009-01-01

The coordination chemistry of copper(I) halides to the homoleptic, N-heterocyclic carbene Au(I) complexes [Au(CH{sub 3}imCH{sub 2}quin){sub 2}]BF{sub 4} and [Au(CH{sub 3}imCH{sub 2}py){sub 2}]BF{sub 4} was explored. The reaction of CuX (X = Cl, Br, I) with either [Au(CH{sub 3}imCH{sub 2}quin){sub 2}]BF{sub 4} or [Au(CH{sub 3}imCH{sub 2}py){sub 2}]BF{sub 4} produces trimetallic complexes containing Cu{sub 2}X{sub 2}-butterfly copper clusters coordinated to the two imine moieties. The triangular arrangement of the metals places the gold(I) center in close proximity ({approx}2.5-2.6 {angstrom}) to the centroid of the Cu-Cu vector. The Cu-Cu separations vary as a function of bridging halide with the shortest Cu-Cu separationsmore » of {approx}2.5 {angstrom} found in the iodo-complexes and the longest separations of 2.9 {angstrom} found in the bridging chloride complexes. In all six complexes the Au-Cu separations range from {approx}2.8 to 3.0 {angstrom}. In the absence of halides, the dimetallic complex [AuCu(CH{sub 3}imCH{sub 2}py){sub 2}(NCCH{sub 3}){sub 2}](BF{sub 4}){sub 2}, containing a long Au-Cu distance of {approx}4.72 {angstrom} is formed. Additionally, as the byproduct of the reaction of CuBr with [Au(CH{sub 3}imCH{sub 2}quin){sub 2}]BF{sub 4} the deep-red, dimetallic compound, AuCuBr{sub 2}(CH{sub 3}imCH{sub 2}quin){sub 2}, was isolated in very low yield. All of these complexes were studied by NMR spectroscopy, mass spectrometry, and the copper containing species were additionally characterized by X-ray crystallography. In solution the copper centers dissociate from the gold complexes, but as shown by XANES and EXAFS spectroscopy, at low temperature the Cu-Cu linkage is broken, and the individual copper(I) halides reposition themselves to opposite sides of the gold complex while remaining coordinated to one imine moiety. In the solid state all of the complexes are photoluminescent, though the nature of the excited state was not determined.« less

Preparation of PVA/Co/Ag film and evaluation of its magnetic and microstructural properties

NASA Astrophysics Data System (ADS)

Banerjee, M.; Sachdev, Preeti; Mukherjee, G. S.

2012-05-01

PVA/Co/Ag film has been prepared by sputtering Co followed by Ag in polyvinyl alcohol (PVA) matrix film by IBS technique, so as to get a 9 nm (thick) layer of Co metal nanoparticles followed by a protective 4 nm (thick) layer of Ag nanoparticles. Grazing incidence x-ray diffraction (GIXRD) pattern of the film reveals the formation of nanocrystalline Co with hcp phase. GIXRD pattern also indicates that there is no change in the crystalline structure of PVA even after sputtering of the metallic nanoparticles. The average particle size of Co nanoparticles as evaluated using Scherrer formula is found to be about 2.64 nm. UV visible absorption pattern of the film sample showed SPR peaks of Co and Ag metals in their nano size level embedded in the PVA matrix system. XPS study confirms the metallic nature of Co and Ag nanoparticles; and the depth profiling study reveals that both the metal nanoparticles have been embedded in the PVA matrix system. Surface morphology of such film has been studied using AFM; and the magnetic behaviour of the film studied by using MOKE shows soft ferromagnetic behaviour in this PVA/Co/Ag system.

Experimental study and detailed modeling of toluene degradation in a low-pressure stoichiometric premixed CH4/O2/N2 flame.

PubMed

Bakali, A El; Dupont, L; Lefort, B; Lamoureux, N; Pauwels, J F; Montero, M

2007-05-17

Temperature and mole fraction profiles have been measured in laminar stoichiometric premixed CH4/O2/N2 and CH4/1.5%C6H5CH3/O2/N2 flames at low pressure (0.0519 bar) by using thermocouple, molecular beam/mass spectrometry (MB/MS), and gas chromatography/mass spectrometry (GC/MS) techniques. The present study completes our previous work performed on the thermal degradation of benzene in CH4/O2/N2 operating at similar conditions. Mole fraction profiles of reactants, final products, and reactive and stable intermediate species have been analyzed. The main intermediate aromatic species analyzed in the methane-toluene flame were benzene, phenol, ethylbenzene, benzylalcohol, styrene, and benzaldehyde. These new experimental results have been modeled with our previous model including submechanisms for aromatics (benzene up to p-xylene) and aliphatic (C1 up to C7) oxidation. Good agreement has been observed for the main species analyzed. The main reaction paths governing the degradation of toluene in the methane flame were identified, and it occurs mainly via the formation of benzene (C6H5CH3 + H = C6H6 + CH3) and benzyl radical (C6H5CH3 + H = C6H5CH2 + H2). Due to the abundance of methyl radicals, it was observed that recombination of benzyl and methyl is responsible for main monosubstitute aromatic species analyzed in the methane-toluene flame. The oxidation of these substitute species led to cyclopentadienyl radical as observed in a methane-benzene flame.

One-pot, facile fabrication of a Ag3PO4-based ternary Z-scheme photocatalyst with excellent visible-light photoactivity and anti-photocorrosion performance

NASA Astrophysics Data System (ADS)

Xie, Mingyuan; Zhang, Tailiang

2018-04-01

Ag3PO4 can-not be widely used as an efficient photocatalyst in practical applications because of its susceptibility to photocorrosion. In this study, a novel, ternary Z-scheme photocatalytic system containing graphene oxide (GO), Ag3PO4 and SnS2 was fabricated by a one-pot, mild, in-situ precipitation method successfully. Using Rhodamine B (RhB) as the target of elimination, GO/Ag3PO4/SnS2 exhibited outstanding photocatalytic and anti-photocorrosion properties compared with those of Ag3PO4, Ag3PO4/SnS2 and GO/Ag3PO4. RhB was thoroughly degraded over the optimized GO/Ag3PO4/SnS2 nanocomposite after only 15 min under visible-light irradiation; this result is approximately 2.14, 3.33 and 5.83 times faster than that of GO/Ag3PO4, Ag3PO4/SnS2 and Ag3PO4, respectively. After three reuses, the photocatalytic activity of the ternary composite slightly decreased but remained 2.36, 4.08 and 12.70 times higher than those of the reused GO/Ag3PO4, Ag3PO4/SnS2 and Ag3PO4, respectively. In this system, the efficient separation and migration of the photoinduced current carriers in Ag3PO4 was realized through a double Z-scheme electron-transfer mechanism in which the GO nanosheets acted as the photocatalyst and electron mediator, thereby enhancing the photoactivity and stability of Ag3PO4. The present study provides a new perspective for enhancing photocatalytic and anti-photocorrosion performances in perishable photocatalysts for organic sewage and other environmental contamination treatments.

Phase Equilibria and Thermodynamic Descriptions of Ag-Ge and Ag-Ge-Ni Systems

NASA Astrophysics Data System (ADS)

Rajkumar, V. B.; Chen, Sinn-Wen

2018-07-01

Gibbs energy modeling of Ag-Ge and Ag-Ge-Ni systems was done using the calculation of the phase diagram method with associated data from this work and relevant literature information. In the Ag-Ge system, the solidus temperatures of Ag-rich alloys are measured using differential thermal analysis, and the energy of mixing for the FCC_A1 phase is calculated using the special quasi-random structures technique. The isothermal sections of the Ag-Ge-Ni system at 1023 K and 673 K are also experimentally determined. These data and findings in the relevant literature are used to model the Gibbs energy of the Ag-Ge and Ag-Ge- Ni systems. A reaction scheme and a liquidus projection of the Ag-Ge-Ni system are determined.

Sea-urchin-like Fe3O4@C@Ag particles: an efficient SERS substrate for detection of organic pollutants

NASA Astrophysics Data System (ADS)

Ye, Yingjie; Chen, Jin; Ding, Qianqian; Lin, Dongyue; Dong, Ronglu; Yang, Liangbao; Liu, Jinhuai

2013-06-01

Ag-coated sea-urchin-like Fe3O4@C core-shell particles can be synthesized by a facile one-step solvothermal method, followed by deposition of high-density Ag nanoparticles onto the carbon surface through an in situ growth process, respectively. The as-synthesized Ag-coated Fe3O4@C particles can be used as a surface-enhanced Raman scattering (SERS) substrate holding reproducible properties under an external magnetic force. The magnetic function of the particles allows concentrating the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. In contrast to the traditional SERS substrates, the present Fe3O4@C@Ag particles hold the advantages of enrichment of organic pollutants for improving SERS detection limit and recycled utilization.Ag-coated sea-urchin-like Fe3O4@C core-shell particles can be synthesized by a facile one-step solvothermal method, followed by deposition of high-density Ag nanoparticles onto the carbon surface through an in situ growth process, respectively. The as-synthesized Ag-coated Fe3O4@C particles can be used as a surface-enhanced Raman scattering (SERS) substrate holding reproducible properties under an external magnetic force. The magnetic function of the particles allows concentrating the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. In contrast to the traditional SERS substrates, the present Fe3O4@C@Ag particles hold the advantages of enrichment of organic pollutants for improving SERS detection limit and recycled utilization. Electronic supplementary information (ESI) available: Additional XRD patterns and SEM images of Fe3O4@C particles, SERS spectra of 4-ATP and 4-MPY using Fe3O4@C@Ag particles as the active substrates, magnetic behaviour of Fe3O4@C and Fe3O4@C@Ag particles. See DOI: 10.1039/c3nr01273e

Clinical and Virological Characteristics of Chronic Hepatitis B Patients with Coexistence of HBsAg and Anti-HBs.

PubMed

Liu, Yong; Zhang, Le; Zhou, Jin-Yong; Pan, Jinshun; Hu, Wei; Zhou, Yi-Hua

2016-01-01

Coexistence of hepatitis B surface antigen (HBsAg) and antibody against HBsAg (anti-HBs) comprises an atypical serological profile in patients with chronic hepatitis B virus (HBV) infection. In this study, in total 94 patients with coexisting HBsAg and anti-HBs and 94 age- and sex-matched patients with positive HBsAg were characterized by quantitatively measuring HBsAg and HBV DNA, sequencing large S genes, and observing clinical features. Compared with common hepatitis B patients, the patients with coexisting HBsAg and anti-HBs had lower HBsAg and HBV DNA levels. These two groups had similar rate of pre-S deletion mutations. However, in patients with coexisting HBsAg and anti-HBs, more amino acid substitutions in the a determinant of S gene were observed in HBV genotype C, but not in genotype B. Fourteen patients with coexisting HBsAg and anti-HBs were followed up for an average of 15.5 months. There were no significant changes in the levels of HBsAg, anti-HBs, HBV DNA and ALT over the follow-up period. Compared with the baseline sequences, amino acid substitutions in the MHR of HBsAg occurred in 14.3% (2/14) patients. In conclusion, coexistence of HBsAg and anti-HBs may be associated with higher frequency of mutations in the a determinant of HBV genotype C.

Self-assembled Ag nanoparticle network passivated by a nano-sized ZnO layer for transparent and flexible film heaters

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

Seo, Ki-Won; Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.kr; Kim, Min-Yi

2015-12-15

We investigated a self-assembled Ag nanoparticle network electrode passivated by a nano-sized ZnO layer for use in high-performance transparent and flexible film heaters (TFFHs). The low temperature atomic layer deposition of a nano-sized ZnO layer effectively filled the uncovered area of Ag network and improved the current spreading in the self-assembled Ag network without a change in the sheet resistance and optical transmittance as well as mechanical flexibility. The time-temperature profiles and heat distribution analysis demonstrate that the performance of the TFTH with the ZnO/Ag network is superior to that of a TFFH with Ag nanowire electrodes. In addition, themore » TFTHs with ZnO/Ag network exhibited better stability than the TFFH with a bare Ag network due to the effective current spreading through the nano-sized ZnO layer.« less

First-principles study of the electronic properties and discharge profile of AgNa(VO2F2)2

NASA Astrophysics Data System (ADS)

Onoue, Masatoshi; Trimarchi, Giancarlo; Freeman, Arthur J.

2014-03-01

Implantable cardiac defibrillators (ICDs) require batteries with high capacities and high discharge rates to ensure the optimal operation of the device over several years. Ag2V4O11 has been a cathode material of choice for the ICDs owing to its high capacity and fast rate of electronic discharge. To reduce ICD size and improve ICD performance, a new cathode material would need to display a higher volumetric capacity and redox potential. Recently, the new cathode compound AgNa(VO2F2)2 (SSVOF) was synthesized and displayed favorable voltage for sodium-ion batteries. However, the discharge reaction has been unclear. In this presentation, we study the discharge reaction of SSVOF through DFT calculations. All calculations are performed within the PAW method using the GGA and GGA + U functionals. Among several possible reactions, we focus on the reaction Ag X + A --> AX + Ag, where X is Na(VO2F2)2 and A is Li or Na. In this reaction, the discharge occurs by replacing Ag with A. The calculated discharge potential for Li is 3.3 V in GGA and 2.9 V in GGA + U and that for Na is 3.1 V in GGA and 2.8 V in GGA + U . These values are consistent with the experimental ones. Supported by the DOE ER46536 Program.

CH-53K Heavy Lift Replacement Helicopter (CH-53K)

DTIC Science & Technology

2015-12-01

Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-390 CH-53K Heavy Lift Replacement Helicopter (CH-53K) As of FY 2017 President’s Budget...December 2015 SAR March 4, 2016 10:04:18 UNCLASSIFIED 4 Col Henry Vanderborght PMA-261 Heavy Lift Helicopters Program Executive Office - Air, Anti...Replacement Helicopter (CH-53K) DoD Component Navy Responsible Office References SAR Baseline (Development Estimate) Defense Acquisition Executive (DAE

A first principles study on the electronic origins of silver segregation at the Ag-Au (111) surface

NASA Astrophysics Data System (ADS)

Hoppe, Sandra; Müller, Stefan

2017-12-01

The special electronic structure of gold gives rise to many interesting phenomena, such as its color. The surface segregation of the silver-gold system has been the subject of numerous experimental and theoretical studies, yielding conflicting results ranging from strong Ag surface enrichment to Au surface segregation. Via a combined approach of density functional theory (DFT) and statistical physics, we have analyzed the segregation at the Ag-Au (111) surface with different Ag bulk concentrations. Interestingly, we observe a moderate Au surface segregation, which is due to a charge transfer from the less electronegative Ag to Au. Canonical Monte Carlo simulations suggest that the calculated concentration profile with a Au-enriched surface layer remains stable up to higher temperatures. However, the presence of adsorbed oxygen reverses the segregation behavior and leads to strong Ag enrichment of the surface layer.

Dependence of Ag/Ga composition ratio in AgGaSe2 thin film

NASA Astrophysics Data System (ADS)

Matsuo, H.; Yoshino, K.; Ikari, T.

2006-09-01

AgGaSe2 thin film was deposited on glass substrates by vacuum evaporation method. The starting material was mixed Ag2Se and Ga2Se3 powders. Ag/Ga ratios of the samples were 1.5, 1.2, 1.0, 0.8, 0.7 and 0.4. The samples were annealed from 100 to 600 °C for 10 min. After these processes, single phase AgGaSe2 thin films could be obtained except Ag/Ga ratio of 0.4 at annealing temperature of 600 °C. Ag-rich samples had large grain. On the other hand, Ga-rich samples had small grain. Furthermore, Ga-rich and Ag-rich samples indicated p- and n-types because of Ag- and/or Ga-vacancy and Se-vacancy, respectively.

Assessing fugitive emissions of CH4 from high-pressure gas pipelines

NASA Astrophysics Data System (ADS)

Worrall, Fred; Boothroyd, Ian; Davies, Richard

2017-04-01

The impact of unconventional natural gas production using hydraulic fracturing methods from shale gas basins has been assessed using life-cycle emissions inventories, covering areas such as pre-production, production and transmission processes. The transmission of natural gas from well pad to processing plants and its transport to domestic sites is an important source of fugitive CH4, yet emissions factors and fluxes from transmission processes are often based upon ver out of date measurements. It is important to determine accurate measurements of natural gas losses when compressed and transported between production and processing facilities so as to accurately determine life-cycle CH4 emissions. This study considers CH4 emissions from the UK National Transmission System (NTS) of high pressure natural gas pipelines. Mobile surveys of CH4 emissions using a Picarro Surveyor cavity-ring-down spectrometer were conducted across four areas in the UK, with routes bisecting high pressure pipelines and separate control routes away from the pipelines. A manual survey of soil gas measurements was also conducted along one of the high pressure pipelines using a tunable diode laser. When wind adjusted 92 km of high pressure pipeline and 72 km of control route were drive over a 10 day period. When wind and distance adjusted CH4 fluxes were significantly greater on routes with a pipeline than those without. The smallest leak detectable was 3% above ambient (1.03 relative concentration) with any leaks below 3% above ambient assumed ambient. The number of leaks detected along the pipelines correlate to the estimated length of pipe joints, inferring that there are constant fugitive CH4 emissions from these joints. When scaled up to the UK's National Transmission System pipeline length of 7600 km gives a fugitive CH4 flux of 4700 ± 2864 kt CH4/yr - this fugitive emission from high pressure pipelines is 0.016% of the annual gas supply.

Methane correction factors for estimating emissions from aerobic wastewater treatment facilities based on field data in Mexico and on literature review.

PubMed

Noyola, A; Paredes, M G; Güereca, L P; Molina, L T; Zavala, M

2018-10-15

Wastewater treatment (WWT) may be an important source of methane (CH 4 ), a greenhouse gas with significant global warming potential. Sources of CH 4 emissions from WWT facilities can be found in the water and in the sludge process lines. Among the methodologies for estimating CH 4 emissions inventories from WWT, the more adopted are the guidelines of the Intergovernmental Panel on Climate Change (IPCC), which recommends default emission factors (Tier 1) depending on WWT systems. Recent published results show that well managed treatment facilities may emit CH 4 , due to dissolved CH 4 in the influent wastewater; in addition, biological nutrient removal also will produce this gas in the anaerobic (or anoxic) steps. However, none of these elements is considered in the current IPCC guidelines. The aim of this work is to propose modified (and new) methane correction factors (MCF) regarding the current Tier 1 IPCC guidelines for CH 4 emissions from aerobic treatment systems, with and without anaerobic sludge digesters, focusing on intertropical countries. The modifications are supported on in situ assessment of fugitive CH 4 emissions in two facilities in Mexico and on relevant literature data. In the case of well-managed centralized aerobic treatment plant, a MCF of 0.06 (instead of the current 0.0) is proposed, considering that the assumption of a CH 4 -neutral treatment facility, as established in the IPCC methodology, is not supported. Similarly, a MCF of 0.08 is proposed for biological nutrient removal processes, being a new entry in the guidelines. Finally, a one-step straightforward calculation is proposed for centralized aerobic treatment plants with anaerobic digesters that avoids confusion when selecting the appropriate default MCF based on the Tier 1 IPCC guidelines. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Dynamics of the F(-) + CH3I → HF + CH2I(-) Proton Transfer Reaction.

PubMed

Zhang, Jiaxu; Xie, Jing; Hase, William L

2015-12-17

Direct chemical dynamics simulations, at collision energies Erel of 0.32 and 1.53 eV, were performed to obtain an atomistic understanding of the F(-) + CH3I reaction dynamics. There is only the F(-) + CH3I → CH3F + I(-) bimolecular nucleophilic substitution SN2 product channel at 0.32 eV. Increasing Erel to 1.53 eV opens the endothermic F(-) + CH3I → HF + CH2I(-) proton transfer reaction, which is less competitive than the SN2 reaction. The simulations reveal proton transfer occurs by two direct atomic-level mechanisms, rebound and stripping, and indirect mechanisms, involving formation of the F(-)···HCH2I complex and the roundabout. For the indirect trajectories all of the CH2I(-) is formed with zero-point energy (ZPE), while for the direct trajectories 50% form CH2I(-) without ZPE. Without a ZPE constraint for CH2I(-), the reaction cross sections for the rebound, stripping, and indirect mechanisms are 0.2 ± 0.1, 1.2 ± 0.4, and 0.7 ± 0.2 Å(2), respectively. Discarding trajectories that do not form CH2I(-) with ZPE reduces the rebound and stripping cross sections to 0.1 ± 0.1 and 0.7 ± 0.5 Å(2). The HF product is formed rotationally and vibrationally unexcited. The average value of J is 2.6 and with histogram binning n = 0. CH2I(-) is formed rotationally excited. The partitioning between CH2I(-) vibration and HF + CH2I(-) relative translation energy depends on the treatment of CH2I(-) ZPE. Without a CH2I(-) ZPE constraint the energy partitioning is primarily to relative translation with little CH2I(-) vibration. With a ZPE constraint, energy partitioning to CH2I(-) rotation, CH2I(-) vibration, and relative translation are statistically the same. The overall F(-) + CH3I rate constant at Erel of both 0.32 and 1.53 eV is in good agreement with experiment and negligibly affected by the treatment of CH2I(-) ZPE, since the SN2 reaction is the major contributor to the total reaction rate constant. The potential energy surface and reaction dynamics for F

Template synthesis of Ag/AgCl microrods and their efficient visible light-driven photocatalytic performance

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

Chen, Hua; Xiao, Liang; Huang, Jianhua, E-mail: jhhuang@zstu.edu.cn

2014-09-15

Highlights: • Preparation ofAg/AgCl microrods by reaction of Ag{sub 2}WO{sub 4} microrods with NaCl solution. • Generation of metallic Ag is induced by the ambient light in the synthesis process. • Ag/AgCl shows excellent visible light-driven photodegradation of organic dyes. - Abstract: Ag/AgCl microrods, aggregated by nanoparticles with a diameter ranging from 100 nm to 2 μm, were prepared by an ion-exchange reaction at 80 °C between Ag{sub 2}WO{sub 4} template and NaCl solution. The existence of metallic Ag species was confirmed by XRD, DRS and XPS measurements. Ag/AgCl microrods showed excellent photocatalytic activity for the degradation of rhodamine Bmore » and methylene blue under visible light irradiation. The degradation rate constants of rhodamine B and methylene blue are 0.176 and 0.114 min{sup −1}, respectively. The cycling photodegradation experiments suggest that Ag/AgCl microds could be employed as stable plasmonic photocatalysts for the degradation of organic dyes under visible light irradiation.« less

An Ab Initio Study of the Low-Lying Doublet States of AgO and AgS

NASA Technical Reports Server (NTRS)

Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

1990-01-01

Spectroscopic constants (D(sub o), r(sub e), mu(sub e), T(sub e)) are determined for the doublet states of AgO and AgS below approx. = 30000/cm. Large valence basis sets are employed in conjunction with relativistic effective core potentials (RECPs). Electron correlation is included using the modified coupled-pair functional (MCPF) and multireference configuration interaction (MRCI) methods. The A(sup 2)Sigma(sup +) - X(sup 2)Pi band system is found to occur in the near infrared (approx. = 9000/cm) and to be relatively weak with a radiative lifetime of 900 microns for A(sup 2)Sigma(sup +) (upsilon = 0). The weakly bound C(sup 2)Pi state (our notation), the upper state of the blue system, is found to require high levels of theoretical treatment to determine a quantitatively accurate potential. The red system is assigned as a transition from the C(sup 2)Pi state to the previously unobserved A(sup 2)Sigma(sup +) state. Several additional transitions are identified that should be detectable experimentally. A more limited study is performed for the vertical excitation spectrum of AgS. In addition, a detailed all-electron study of the X(sup 2)Pi and A(sup 2)Sigma(sup +) states of AgO is carried out using large atomic natural orbital (ANO) basis sets. Our best calculated D(sub o) value for AgO is significantly less than the experimental value, which suggests that there may be some systematic error in the experimental determination.

Homogeneous synthesis of Ag nanoparticles-doped water-soluble cellulose acetate for versatile applications.

PubMed

Cao, Jie; Sun, Xunwen; Zhang, Xinxing; Lu, Canhui

2016-11-01

We report a facile and efficient approach for synthesis of well-dispersed and stable silver nanoparticles (Ag NPs) using water-soluble cellulose acetate (CA) as both reductant and stabilizer. Partially substituted CA with highly active hydroxyl groups and excellent water-solubility is able to reduce silver ions in homogeneous aqueous medium effectively. The synthesized Ag NPs were characterized by UV-vis spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive X-ray spectroscope analysis. The as-prepared Ag NPs were well-dispersed, showing a surface plasmon resonance peak at 426nm. The resulted Ag NPs@CA nanohybrids exhibit high catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH 4 . Meanwhile, the nanohybrids are also effective in inhibiting the growth of bacterial. This environmentally friendly method promotes the use of renewable natural resources to prepare a variety of inorganic-organic materials for catalysis, antibacterial, sensors and other applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Capture and dissociation in the complex-forming CH + H2 → CH2 + H, CH + H2 reactions.

PubMed

González, Miguel; Saracibar, Amaia; Garcia, Ernesto

2011-02-28

The rate coefficients for the capture process CH + H(2)→ CH(3) and the reactions CH + H(2)→ CH(2) + H (abstraction), CH + H(2) (exchange) have been calculated in the 200-800 K temperature range, using the quasiclassical trajectory (QCT) method and the most recent global potential energy surface. The reactions, which are of interest in combustion and in astrochemistry, proceed via the formation of long-lived CH(3) collision complexes, and the three H atoms become equivalent. QCT rate coefficients for capture are in quite good agreement with experiments. However, an important zero point energy (ZPE) leakage problem occurs in the QCT calculations for the abstraction, exchange and inelastic exit channels. To account for this issue, a pragmatic but accurate approach has been applied, leading to a good agreement with experimental abstraction rate coefficients. Exchange rate coefficients have also been calculated using this approach. Finally, calculations employing QCT capture/phase space theory (PST) models have been carried out, leading to similar values for the abstraction rate coefficients as the QCT and previous quantum mechanical capture/PST methods. This suggests that QCT capture/PST models are a good alternative to the QCT method for this and similar systems.

Synthesis and antibacterial evaluation of calcinated Ag-doped nano-hydroxyapatite with dispersibility.

PubMed

Furuzono, Tsutomu; Motaharul, Mazumder; Kogai, Yasumichi; Azuma, Yoshinao; Sawa, Yoshiki

2015-05-01

Dispersible hydroxyapatite (HAp) nanoparticles are very useful for applying a monolayer to implantable medical devices using the nano-coating technique. To improve tolerance to infection on implanted medical devices, silver-doped HAp (Ag-HAp) nanoparticles with dispersiblity and crystallinity were synthesized, avoiding calcination-induced sintering, and evaluated for antibacterial activity. The Ca10-xAgx(PO4)6(OH)2 with x = 0 and 0.2 were prepared by wet chemical processing at 100°C. Before calcination at 700°C for 2 h, two kinds of anti-sintering agents, namely a Ca(NO3)2 (Ca salt) and a polyacrylic acid/Ca salt mixture (PAA-Ca), were used. Escherichia coli was used to evaluate the antibacterial activity of the nanopowder. When PAA-Ca was used as an anti-sintering agent in calcination to prepare the dispersible nanoparticles, strong metallic Ag peaks were observed at 38.1° and 44.3° (2θ) in the X-ray diffraction (XRD) profile. However, the Ag peak was barely observed when Ca salt was used alone as the anti-sintering agent. Thus, using Ca salt alone was more effective for preparation of dispersible Ag-HAp than PAA-Ca. The particle average size of Ag-HAp with 0.5 mol% of Ag content was found to be 325 ± 70 nm when the formation of large particleaggregations was prevented, as determined by dynamic light scattering instrument. The antibacterial activity of the Ag-HAp nanoparticles possessing 0.5 mol% against E. coli was greater than 90.0%. Dispersible and crystalline nano Ag-HAp can be obtained by using Ca salt alone as an anti-sintering agent. The nanoparticles showed antibacterial activity.

Organic pollutant photodecomposition by Ag/KNbO 3 nanocomposites: A combined experimental and theoretical study

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

Zhang, Tingting; Liu, Ping; Lei, Wanying

In this study, Ag nanoparticles supported on well-defined perovskite orthorhombic KNbO 3 nanowires are synthesized via facile photoreduction and systematically characterized by XRD, Raman, DRUV–vis, XPS, PL, TEM, HRTEM, and HAADF-STEM. The photoreactivity of Ag/KNbO 3 nanocomposites as a function of Ag contents (0.4–2.8 wt %) is assessed toward aqueous rhodamine B degradation under UV- and visible-light, respectively. It is found that the UV-induced photoreactivity initially increases and then decreases with increasing Ag contents. At an optimal Ag content (ca. 1.7 wt %), the greatest photoreactivity is achieved under UV light, with the photocatalytic reaction rate of 1.7 wt %more » Ag/KNbO 3 exceeding that of pristine KNbO 3 by a factor of ca. 13. In contrast, visible light-induced photoreactivity monotonically increases with increasing Ag contents in the range of 0.4–2.8 wt %. On the basis of the detected active species and intermediate products in the photocatalytic processes, conjugated structure cleavage and N-deethylation are revealed to be the respective predominant pathway under UV and visible-light illumination. To gain an insight into the observed photoreactivity, the electronic properties of Ag/KNbO 3 have been investigated using spin-polarized DFT calculations. Herein, Ag extended adlayers (1–4 ML) on the slab models of KNbO 3 (101) are employed to mimic large supported Ag nanoparticles. A Bader analysis of the electron density shows a small net charge transfer (ca. 0.1 e) from KNbO 3 to Ag. The electron localization function of Ag/KNbO 3 (101) illustrates that Ag adlayers with thickness larger than 2 ML are essentially metallic, and weak polarization occurs at the interface. In addition, the metallic Ag adlayers generate a continuum of Ag bandgap states, which play a key role in determining different Ag content-dependent behavior between UV and visible-light illumination.« less

Organic pollutant photodecomposition by Ag/KNbO 3 nanocomposites: A combined experimental and theoretical study

DOE PAGES

Zhang, Tingting; Liu, Ping; Lei, Wanying; ...

2016-01-12

In this study, Ag nanoparticles supported on well-defined perovskite orthorhombic KNbO 3 nanowires are synthesized via facile photoreduction and systematically characterized by XRD, Raman, DRUV–vis, XPS, PL, TEM, HRTEM, and HAADF-STEM. The photoreactivity of Ag/KNbO 3 nanocomposites as a function of Ag contents (0.4–2.8 wt %) is assessed toward aqueous rhodamine B degradation under UV- and visible-light, respectively. It is found that the UV-induced photoreactivity initially increases and then decreases with increasing Ag contents. At an optimal Ag content (ca. 1.7 wt %), the greatest photoreactivity is achieved under UV light, with the photocatalytic reaction rate of 1.7 wt %more » Ag/KNbO 3 exceeding that of pristine KNbO 3 by a factor of ca. 13. In contrast, visible light-induced photoreactivity monotonically increases with increasing Ag contents in the range of 0.4–2.8 wt %. On the basis of the detected active species and intermediate products in the photocatalytic processes, conjugated structure cleavage and N-deethylation are revealed to be the respective predominant pathway under UV and visible-light illumination. To gain an insight into the observed photoreactivity, the electronic properties of Ag/KNbO 3 have been investigated using spin-polarized DFT calculations. Herein, Ag extended adlayers (1–4 ML) on the slab models of KNbO 3 (101) are employed to mimic large supported Ag nanoparticles. A Bader analysis of the electron density shows a small net charge transfer (ca. 0.1 e) from KNbO 3 to Ag. The electron localization function of Ag/KNbO 3 (101) illustrates that Ag adlayers with thickness larger than 2 ML are essentially metallic, and weak polarization occurs at the interface. In addition, the metallic Ag adlayers generate a continuum of Ag bandgap states, which play a key role in determining different Ag content-dependent behavior between UV and visible-light illumination.« less

Ag out-surface diffusion in crystalline SiC with an effective SiO 2 diffusion barrier

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

Xue, H.; Xiao, H. Y.; Zhu, Z.

2015-05-07

For applications of tristructural isotropic (TRISO) fuel particles in high temperature reactors, release of radioactive Ag isotope ( 110mAg) through the SiC coating layer is a safety concern. In order to understand the diffusion mechanism, Ag ion implantations near the surface and in the bulk were performed by utilizing different ion energies and energy-degrader foils. High temperature annealing was carried out on the as-irradiated samples to study the possible out-surface diffusion. Before and after annealing, Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) measurements were employed to obtain the elemental profiles of the implanted samples. Our results suggestmore » little migration of buried Ag in the bulk, and an out-diffusion of the implanted Ag in the near-surface region of single crystal SiC. It is also found that a SiO 2 layer, which was formed during annealing, may serve as an effective barrier to reduce or prevent Ag out diffusion through the SiC coating layer.« less

Ag Out-surface Diffusion In Crystalline SiC With An Effective SiO2 Diffusion Barrier

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

Xue, H.; Xiao, Haiyan Y.; Zhu, Zihua

2015-09-01

For applications of tristructural isotropic (TRISO) fuel particles in high temperature reactors, release of radioactive Ag isotope (110mAg) through the SiC coating layer is a safety concern. To understand the diffusion mechanism, Ag ion implantations near the surface and in the bulk were performed by utilizing different ion energies and energy-degrader foils. High temperature annealing was carried out on the as-irradiated samples to study the possible out-surface diffusion. Before and after annealing, Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) measurements were employed to obtain the elemental profiles of the implanted samples. The results suggest little migration ofmore » buried Ag in the bulk, and an out-diffusion of the implanted Ag in the near-surface region of single crystal SiC. It is also found that a SiO2 layer, which was formed during annealing, may serve as an effective barrier to reduce or prevent Ag out diffusion through the SiC coating layer.« less

Normalization, bias correction, and peak calling for ChIP-seq

PubMed Central

Diaz, Aaron; Park, Kiyoub; Lim, Daniel A.; Song, Jun S.

2012-01-01

Next-generation sequencing is rapidly transforming our ability to profile the transcriptional, genetic, and epigenetic states of a cell. In particular, sequencing DNA from the immunoprecipitation of protein-DNA complexes (ChIP-seq) and methylated DNA (MeDIP-seq) can reveal the locations of protein binding sites and epigenetic modifications. These approaches contain numerous biases which may significantly influence the interpretation of the resulting data. Rigorous computational methods for detecting and removing such biases are still lacking. Also, multi-sample normalization still remains an important open problem. This theoretical paper systematically characterizes the biases and properties of ChIP-seq data by comparing 62 separate publicly available datasets, using rigorous statistical models and signal processing techniques. Statistical methods for separating ChIP-seq signal from background noise, as well as correcting enrichment test statistics for sequence-dependent and sonication biases, are presented. Our method effectively separates reads into signal and background components prior to normalization, improving the signal-to-noise ratio. Moreover, most peak callers currently use a generic null model which suffers from low specificity at the sensitivity level requisite for detecting subtle, but true, ChIP enrichment. The proposed method of determining a cell type-specific null model, which accounts for cell type-specific biases, is shown to be capable of achieving a lower false discovery rate at a given significance threshold than current methods. PMID:22499706

Highly Stable Graphene-Based Nanocomposite (GO-PEI-Ag) with Broad-Spectrum, Long-Term Antimicrobial Activity and Antibiofilm Effects.

PubMed

Zhao, Rongtao; Kong, Wen; Sun, Mingxuan; Yang, Yi; Liu, Wanying; Lv, Min; Song, Shiping; Wang, Lihua; Song, Hongbin; Hao, Rongzhang

2018-05-30

Various silver nanoparticle (AgNP)-decorated graphene oxide (GO) nanocomposites (GO-Ag) have received increasing attention owing to their antimicrobial activity and biocompatibility; however, their aggregation in physiological solutions and the generally complex synthesis methods warrant improvement. This study aimed to synthesize a polyethyleneimine (PEI)-modified and AgNP-decorated GO nanocomposite (GO-PEI-Ag) through a facile approach through microwave irradiation without any extra reductants and surfactants; its antimicrobial activity was investigated on Gram-negative/-positive bacteria (including drug-resistant bacteria) and fungi. Compared with GO-Ag, GO-PEI-Ag acquired excellent stability in physiological solutions and electropositivity, showing substantially higher antimicrobial efficacy. Moreover, GO-PEI-Ag exhibited particularly excellent long-term effects, presenting no obvious decline in antimicrobial activity after 1 week storage in physiological saline and repeated use for three times and the lasting inhibition of bacterial growth in nutrient-rich culture medium. In contrast, GO-Ag exhibited a >60% decline in antimicrobial activity after storage. Importantly, GO-PEI-Ag effectively eliminated adhered bacteria, thereby preventing biofilm formation. The primary antimicrobial mechanisms of GO-PEI-Ag were evidenced as physical damage to the pathogen structure, causing cytoplasmic leakage. Hence, stable GO-PEI-Ag with robust, long-term antimicrobial activity holds promise in combating public-health threats posed by drug-resistant bacteria and biofilms.

Optical properties of silicene, Si/Ag(111), and Si/Ag(110)

NASA Astrophysics Data System (ADS)

Hogan, C.; Pulci, O.; Gori, P.; Bechstedt, F.; Martin, D. S.; Barritt, E. E.; Curcella, A.; Prevot, G.; Borensztein, Y.

2018-05-01

We present a state-of-the-art study of the optical properties of free-standing silicene and of single-layer Si one- and two-dimensional (1D and 2D) nanostructures supported on Ag(110) and Ag(111) substrates. Ab initio simulations of reflectance anisotropy spectroscopy (RAS) and surface differential reflectivity spectroscopy (SDRS) applied to the clean Ag surface and Si/Ag interfaces are compared with new measurements. For Si/Ag(110), we confirm a pentagonal nanoribbon geometry, strongly bonded to the substrate, and rule out competing zigzag chain and silicenelike models. For Si/Ag(111), we reproduce the main experimental features and isolate the optical signal of the epitaxial silicene overlayer. The absorption spectrum of a silicene sheet computed including excitonic and local field effects is found to be quite similar to that calculated within an independent particle approximation and shows strong modifications when adsorbed on a Ag substrate. Important details of the computational approach are examined and the origins of the RAS and SDRS signals are explained in terms of the interface and substrate response functions. Our study does not find any evidence for Si adlayers that retain the properties of freestanding silicene.

Gamma ray irradiated AgFeO{sub 2} nanoparticles with enhanced gas sensor properties

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

Wang, Xiuhua, E-mail: xhwang@mail.ahnu.edu.cn; Shi, Zhijie; Yao, Shangwu

2014-11-15

AgFeO{sub 2} nanoparticles were synthesized via a facile hydrothermal method and irradiated by various doses of gamma ray. The products were characterized with X-ray powder diffraction, UV–vis absorption spectrum and transmission electron microscope. The results revealed that the crystal structure, morphology and size of the samples remained unchanged after irradiation, while the intensity of UV–Vis spectra increased with irradiation dose increasing. In addition, gamma ray irradiation improved the performance of gas sensor based on the AgFeO{sub 2} nanoparticles including the optimum operating temperature and sensitivity, which might be ascribed to the generation of defects. - Graphical abstract: Gamma ray irradiationmore » improved the performance of gas sensor based on the AgFeO{sub 2} nanoparticles including sensitivity and optimum operating temperature, which might be ascribed to the generation of defects. - Highlights: • AgFeO{sub 2} nanoparticles were synthesized and irradiated with gamma ray. • AgFeO{sub 2} nanoparticles were employed to fabricate gas sensors to detect ethanol. • Gamma ray irradiation improved the sensitivity and optimum operating temperature.« less

Substantivity of Ag-Ca-Si mesoporous nanoparticles on dentin and its ability to inhibit Enterococcus faecalis.

PubMed

Fan, Wei; Wu, Yujie; Ma, Tengjiao; Li, Yanyun; Fan, Bing

2016-01-01

The main purpose of this study was to investigate the substantivity of Ag-Ca-Si mesoporous nanoparticles (Ag-MCSNs) on dentin and its residual antibacterial effects against Enterococcus faecalis. Ag-MCSNs were fabricated and characterized, ion release profile and pH were tested, and the ability to inhibit planktonic E. faecalis as well as the cytotoxicity was evaluated. Dentin slices were medicated with Ca(OH)2 paste, 2 % chlorhexidine gel and Ag-MCSNs paste for 7 days and then irrigated. Dentin slices were then immersed in E. faecalis suspension for 6 days and then transferred to fresh brain heart infusion solution. The optical density value within 10 h after immersing and transferring were measured and compared among groups. Results indicated that Ag-MCSNs showed high pH, sustained Ag(+)-Ca(2+)-SiO3 (2-) ion release, and high substantivity on dentin. The Ag-MCSNs exhibited strong antibacterial effects against planktonic E. faecalis and much better residual inhibition effects against E. faecalis growth on dentin than Ca(OH)2 paste (P < 0.05). The Ag-MCSNs showed excellent antibacterial ability against E. faecalis and high substantivity on dentin, which might be developed to a new effective intra-canal medicament for human teeth.

AgI/Ag{sub 3}PO{sub 4} hybrids with highly efficient visible-light driven photocatalytic activity

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

Katsumata, Hideyuki, E-mail: hidek@chem.mie-u.ac.jp; Hayashi, Takahiro; Taniguchi, Masanao

Highlights: • AgI/Ag{sub 3}PO{sub 4} hybrid was prepared via an in situ anion-exchange method. • AgI/Ag{sub 3}PO{sub 4} displays the excellent photocatalytic activity under visible light. • AgI/Ag{sub 3}PO{sub 4} readily transforms to be Ag@AgI/Ag{sub 3}PO{sub 4} system. • h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization over AgI/Ag{sub 3}PO{sub 4}. • The activity enhancement is ascribed to a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI. - Abstract: Highly efficient visible-light-driven AgI/Ag{sub 3}PO{sub 4} hybrid photocatalysts with different mole ratios of AgI were prepared via an in situ anion-exchange methodmore » and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) technique. Under visible light irradiation (>420 nm), the AgI/Ag{sub 3}PO{sub 4} photocatalysts displayed the higher photocatalytic activity than pure Ag{sub 3}PO{sub 4} and AgI for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgI/Ag{sub 3}PO{sub 4} with 80% of AgI exhibited the highest photocatalytic activity for the decolorization of AO 7. X-ray photoelectron spectroscopy (XPS) results revealed that AgI/Ag{sub 3}PO{sub 4} readily transformed to be Ag@AgI/Ag{sub 3}PO{sub 4} system while the photocatalytic activity of AgI/Ag{sub 3}PO{sub 4} remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgI/Ag{sub 3}PO{sub 4} hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI, in which Ag nanoparticles act as the charge separation center.« less

Site-selective and stereoselective functionalization of non-activated tertiary C-H bonds

NASA Astrophysics Data System (ADS)

Liao, Kuangbiao; Pickel, Thomas C.; Boyarskikh, Vyacheslav; Bacsa, John; Musaev, Djamaladdin G.; Davies, Huw M. L.

2017-11-01

The synthesis of complex organic compounds usually relies on controlling the reactions of the functional groups. In recent years, it has become possible to carry out reactions directly on the C-H bonds, previously considered to be unreactive. One of the major challenges is to control the site-selectivity because most organic compounds have many similar C-H bonds. The most well developed procedures so far rely on the use of substrate control, in which the substrate has one inherently more reactive C-H bond or contains a directing group or the reaction is conducted intramolecularly so that a specific C-H bond is favoured. A more versatile but more challenging approach is to use catalysts to control which site in the substrate is functionalized. p450 enzymes exhibit C-H oxidation site-selectivity, in which the enzyme scaffold causes a specific C-H bond to be functionalized by placing it close to the iron-oxo haem complex. Several studies have aimed to emulate this enzymatic site-selectivity with designed transition-metal catalysts but it is difficult to achieve exceptionally high levels of site-selectivity. Recently, we reported a dirhodium catalyst for the site-selective functionalization of the most accessible non-activated (that is, not next to a functional group) secondary C-H bonds by means of rhodium-carbene-induced C-H insertion. Here we describe another dirhodium catalyst that has a very different reactivity profile. Instead of the secondary C-H bond, the new catalyst is capable of precise site-selectivity at the most accessible tertiary C-H bonds. Using this catalyst, we modify several natural products, including steroids and a vitamin E derivative, indicating the applicability of this method of synthesis to the late-stage functionalization of complex molecules. These studies show it is possible to achieve site-selectivity at different positions within a substrate simply by selecting the appropriate catalyst. We hope that this work will inspire the design of

BOREAS TGB-1/TGB-3 CH4 Chamber Flux Data over the NSA Fen

NASA Technical Reports Server (NTRS)

Bubier, Jill L.; Moore, Tim R.; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

2000-01-01

The BOREAS TGB-3 team collected methane (CH4) chamber flux measurements at the NSA fen site during May-September 1994 and June-October 1996. Gas samples were extracted approximately every 7 days from chambers and analyzed at the NSA lab facility. The data are provided in tabular ASCII files.

Warming Early Mars With CH4

NASA Astrophysics Data System (ADS)

Justh, H. L.; Kasting, J. F.

2002-12-01

The nature of the ancient climate of Mars remains one of the fundamental unresolved problems in martian research. While the present environment is hostile to life, images from the Mariner, Viking and Mars Global Surveyor missions, have shown geologic features on the martian surface that seem to indicate an earlier period of hydrologic activity. The fact that ancient valley networks and degraded craters have been seen on the martian surface indicates that the early martian climate may have been more Earth-like, with a warmer surface temperature. The presence of liquid water would require a greenhouse effect much larger than needed at present, as the solar constant, S0, was 25% lower 3.8 billion years ago when the channels are thought to have formed (1,2). Previous calculations have shown that gaseous CO2 and H2O alone could not have warmed the martian surface to the temperature needed to account for the presence of liquid water (3). It has been hypothesized that a CO2-H2O atmosphere could keep early Mars warm if it was filled with CO2 ice clouds in the upper martian troposphere (4). Obtaining mean martian surface temperatures above 273 K would require nearly 100% cloud cover, a condition that is unrealistic for condensation clouds on early Mars. Any reduction in cloud cover makes it difficult to achieve warm martian surface temperatures except at high pressures and CO2 clouds could cool the martian surface if they were low and optically thick (5). CO2 and CH4 have been suggested as important greenhouse gases on the early Earth. Our research focuses on the effects of increased concentrations of atmospheric greenhouse gases on the surface temperature of early Mars, with emphasis on the reduced greenhouse gas, CH4. To investigate the possible warming effect of CH4, we modified a one-dimensional, radiative-convective climate model used in previous studies of the early martian climate (5). New cloud-free temperature profiles for various surface pressures and CH4 mixing

Effect of Different CH3NH3PbI3 Morphologies on Photovoltaic Properties of Perovskite Solar Cells

NASA Astrophysics Data System (ADS)

Chen, Lung-Chien; Lee, Kuan-Lin; Wu, Wen-Ti; Hsu, Chien-Feng; Tseng, Zong-Liang; Sun, Xiao Hong; Kao, Yu-Ting

2018-05-01

In this study, the perovskite layers were prepared by two-step wet process with different CH3NH3I (MAI) concentrations. The cell structure was glass/FTO/TiO2-mesoporous/CH3NH3PbI3 (MAPbI3)/spiro-OMeTAD/Ag. The MAPbI3 perovskite films were prepared using high and low MAI concentrations in a two-step process. The perovskite films were optimized at different spin coating speed and different annealing temperatures to enhance the power conversion efficiency (PCE) of perovskite solar cells. The PCE of the resulting device based on the different perovskite morphologies was discussed. The PCE of the best cell was up to 17.42%, open circuit voltage of 0.97 V, short current density of 24.06 mA/cm2, and fill factor of 0.747.

Effect of Different CH3NH3PbI3 Morphologies on Photovoltaic Properties of Perovskite Solar Cells.

PubMed

Chen, Lung-Chien; Lee, Kuan-Lin; Wu, Wen-Ti; Hsu, Chien-Feng; Tseng, Zong-Liang; Sun, Xiao Hong; Kao, Yu-Ting

2018-05-08

In this study, the perovskite layers were prepared by two-step wet process with different CH 3 NH 3 I (MAI) concentrations. The cell structure was glass/FTO/TiO 2 -mesoporous/CH 3 NH 3 PbI 3 (MAPbI 3 )/spiro-OMeTAD/Ag. The MAPbI 3 perovskite films were prepared using high and low MAI concentrations in a two-step process. The perovskite films were optimized at different spin coating speed and different annealing temperatures to enhance the power conversion efficiency (PCE) of perovskite solar cells. The PCE of the resulting device based on the different perovskite morphologies was discussed. The PCE of the best cell was up to 17.42%, open circuit voltage of 0.97 V, short current density of 24.06 mA/cm 2 , and fill factor of 0.747.

HBeAg-induced miR-106b promotes cell growth by targeting the retinoblastoma gene.

PubMed

Samal, Jasmine; Kandpal, Manish; Vivekanandan, Perumal

2017-10-30

Chronic HBV infection is a major cause of hepatocellular carcinoma (HCC). The association between hepatitis B "e" antigen (HBeAg) and HCC is well-established by epidemiological studies. Nonetheless, the biological role of HBeAg in HCC remains enigmatic. We investigate the role of HBeAg in HBV-related HCC. Our findings suggest that HBeAg enhances cell proliferation and accelerates progression from G0/G1 phase to the S phase of the cell cycle in Huh7 cells. Examination of host gene expression and miRNA expression profiles reveals a total of 21 host genes and 12 host miRNAs that were differentially regulated in cells expressing HBeAg. Importantly, HBeAg induced the expression of miR-106b, an oncogenic miRNA. Interestingly, HBeAg-expression results in a significant reduction in the expression of retinoblastoma (Rb) gene, an experimentally validated target of miR-106b. Inhibition of miR-106b significantly increased the expression of the Rb gene, resulting in reduced cell proliferation and slowing of cell cycle progression from the G0/G1 phase to S phase. These observations suggest that the up-regulation of miR-106b by HBeAg contributes to the pathogenesis of HBV-related HCC by down-regulating the Rb gene. Our results highlight a role for HBeAg in HCC and provide a novel perspective on the molecular mechanisms underlying HBV-related HCC.

Conformational and spectroscopic study of xanthogen ethyl formates, ROC(S)SC(O)OCH2CH3. Isolation of CH3CH2OC(O)SH

NASA Astrophysics Data System (ADS)

Juncal, Luciana C.; Cozzarín, Melina V.; Romano, Rosana M.

2015-03-01

ROC(S)SC(O)OCH2CH3, with R = CH3sbnd , (CH3)2CHsbnd and CH3(CH2)2sbnd , were obtained through the reaction between potassium xanthate salts, ROC(S)SK, and ethyl chloroformate, ClC(O)OCH2CH3. The liquid compounds were identified and characterized by 1H and 13C NMR and mass spectrometry. The conformations adopted by the molecules were studied by DFT methods. 6 conformers were theoretically predicted for R = CH3sbnd and (CH3)2CHsbnd , while the conformational flexibility of the n-propyl substituent increases the total number of feasible rotamers to 21. For the three molecules, the conformers can be associated in 3 groups, being the most stable the AS forms - the Cdbnd S double bond anti (A) with respect to the Csbnd S single bond and the Ssbnd C single bond syn (S) with respect to the Cdbnd O double bond - followed by AA and SS conformers. The vibrational spectra were interpreted in terms of the predicted conformational equilibrium, presenting the ν(Cdbnd O) spectral region signals corresponding to the three groups of conformers. A moderated pre-resonance Raman enhancement of the ν(Cdbnd S) vibrational mode of CH3(CH2)2OC(S)SC(O)OCH2CH3 was detected, when the excitation radiation approaches the energy of a n → π∗ electronic transition associated with the Cdbnd S chromophore. UV-visible spectra in different solvents were measured and interpreted in terms of TD-DFT calculations. The unknown molecule CH3CH2OC(O)SH was isolated by the UV-visible photolysis of CH3OC(S)SC(O)OCH2CH3 isolated in Ar matrix, and also obtained as a side-product of the reaction between potassium xanthate salts, ROC(S)SK, and ethyl chloroformate, ClC(O)OCH2CH3.

Thermal decomposition of ethanol. 4. Ab initio chemical kinetics for reactions of H atoms with CH3CH2O and CH3CHOH radicals.

PubMed

Xu, Z F; Xu, Kun; Lin, M C

2011-04-21

The potential energy surfaces of H-atom reactions with CH(3)CH(2)O and CH(3)CHOH, two major radicals in the decomposition and oxidation of ethanol, have been studied at the CCSD(T)/6-311+G(3df,2p) level of theory with geometric optimization carried out at the BH&HLYP/6-311+G(3df,2p) level. The direct hydrogen abstraction channels and the indirect association/decomposition channels from the chemically activated ethanol molecule have been considered for both reactions. The rate constants for both reactions have been calculated at 100-3000 K and 10(-4) Torr to 10(3) atm Ar pressure by microcanonical VTST/RRKM theory with master equation solution for all accessible product channels. The results show that the major product channel of the CH(3)CH(2)O + H reaction is CH(3) + CH(2)OH under atmospheric pressure conditions. Only at high pressure and low temperature, the rate constant for CH(3)CH(2)OH formation by collisonal deactivation becomes dominant. For CH(3)CHOH + H, there are three major product channels; at high temperatures, CH(3)+CH(2)OH production predominates at low pressures (P < 100 Torr), while the formation of CH(3)CH(2)OH by collisional deactivation becomes competitive at high pressures and low temperatures (T < 500 K). At high temperatures, the direct hydrogen abstraction reaction producing CH(2)CHOH + H(2) becomes dominant. Rate constants for all accessible product channels in both systems have been predicted and tabulated for modeling applications. The predicted value for CH(3)CHOH + H at 295 K and 1 Torr pressure agrees closely with available experimental data. For practical modeling applications, the rate constants for the thermal unimolecular decomposition of ethanol giving key accessible products have been predicted; those for the two major product channels taking place by dehydration and C-C breaking agree closely with available literature data.

Ab initio Study of Ag-Based Fluoroperovskite AgMF3 (M = Co and Ni) Compounds

NASA Astrophysics Data System (ADS)

Mubarak, A. A.

2018-01-01

Ab initio calculations of Ag-based fluoroperovskite AgMF3 (M = Co and Ni) compounds are investigated using the full-potential linearized augmented plane wave method. Wien2k and BoltzTrap codes are used to calculate the different physical properties. The structural parameters of the present compounds are within reasonable agreement with previous calculations. This study shows that AgCoF3 and AgNiF3 are anisotropic, ductile, mechanically and thermodynamically stable compounds, where AgCoF3 is found to be stiffer and less compressible than AgNiF3. The spin-polarized electronic band structure illustrates that AgCoF3 is metallic, while AgNiF3 is a semiconductor with indirect (M-D) band gap energy of 0.43 eV. The bonding force between atoms is found to be mainly ionic with some covalent nature. The total magnetic moment of AgCoF3 (3.04 μ B) is found to be higher than that calculated for AgNiF3 (2.00 μ B). Using the magnetic susceptibility calculations, AgCoF3 is classified as antiferromagnetic, whereas AgNiF3 is a ferromagnetic compound. The calculated static refractive index of AgCoF3 (3.85) and AgNiF3 (3.60) is inversely proportional with the energy band gap. Suitable applications are predicted for AgCoF3 and AgNiF3 based on their absorption and reflection properties. Furthermore, beneficial thermoelectric applications are expected for the present compounds due to their large Seebeck coefficient ( S_{{{{AgCoF}}_{ 3} }} = 2.92 × 103 μ {V/K} {and} S_{{{{AgNiF}}3 }} = 2.84 × 103 μ {V/K} ) and their thermoelectric power factor with respect to relaxation time ( S2 σ /t_{{AgNiF3 }} = 1.11 × 109 {W/K}^{ 2} {and} S2 σ /t_{{AgNiF3 }} = 1.28 × 10^{11} {W/K}^{ 2} ).

Ab Initio Chemical Kinetics for the CH3 + O((3)P) Reaction and Related Isomerization-Decomposition of CH3O and CH2OH Radicals.

PubMed

Xu, Z F; Raghunath, P; Lin, M C

2015-07-16

The kinetics and mechanism of the CH3 + O reaction and related isomerization-decomposition of CH3O and CH2OH radicals have been studied by ab initio molecular orbital theory based on the CCSD(T)/aug-cc-pVTZ//CCSD/aug-cc-pVTZ, CCSD/aug-cc-pVDZ, and G2M//B3LYP/6-311+G(3df,2p) levels of theory. The predicted potential energy surface of the CH3 + O reaction shows that the CHO + H2 products can be directly generated from CH3O by the TS3 → LM1 → TS7 → LM2 → TS4 path, in which both LM1 and LM2 are very loose and TS7 is roaming-like. The result for the CH2O + H reaction shows that there are three low-energy barrier processes including CH2O + H → CHO + H2 via H-abstraction and CH2O + H → CH2OH and CH2O + H → CH3O by addition reactions. The predicted enthalpies of formation of the CH2OH and CH3O radicals at 0 K are in good agreement with available experimental data. Furthermore, the rate constants for the forward and some key reverse reactions have been predicted at 200-3000 K under various pressures. Based on the new reaction pathway for CH3 + O, the rate constants for the CH2O + H and CHO + H2 reactions were predicted with the microcanonical variational transition-state/Rice-Ramsperger-Kassel-Marcus (VTST/RRKM) theory. The predicted total and individual product branching ratios (i.e., CO versus CH2O) are in good agreement with experimental data. The rate constant for the hydrogen abstraction reaction of CH2O + H has been calculated by the canonical variational transition-state theory with quantum tunneling and small-curvature corrections to be k(CH2O + H → CHO + H2) = 2.28 × 10(-19) T(2.65) exp(-766.5/T) cm(3) molecule(-1) s(-1) for the 200-3000 K temperature range. The rate constants for the addition giving CH3O and CH2OH and the decomposition of the two radicals have been calculated by the microcanonical RRKM theory with the time-dependent master equation solution of the multiple quantum well system in the 200-3000 K temperature range at 1 Torr to

Synergistic influence of polyoxometalate surface corona towards enhancing the antibacterial performance of tyrosine-capped Ag nanoparticles.

PubMed

Daima, Hemant K; Selvakannan, P R; Kandjani, Ahmad E; Shukla, Ravi; Bhargava, Suresh K; Bansal, Vipul

2014-01-21

We illustrate a new strategy to improve the antibacterial potential of silver nanoparticles (AgNPs) by their surface modification with the surface corona of biologically active polyoxometalates (POMs). The stable POM surface corona was achieved by utilising zwitterionic tyrosine amino acid as a pH-switchable reducing and capping agent of AgNPs. The general applicability of this approach was demonstrated by developing surface coronas of phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) around AgNPs. Our investigations on Gram negative bacterium Escherichia coli demonstrate that in conjugation with AgNPs, the surface corona of POMs enhances the physical damage to the bacterial cells due to synergistic antibacterial action of AgNPs and POMs, and the ability of tyrosine-reduced AgNPs (AgNPs(Y)) to act as an excellent carrier and stabiliser for the POMs. The further extension of this study towards Gram positive bacterium Staphylococcus albus showed a similar toxicity pattern, whereas these nanomaterials were found to be biocompatible for PC3 epithelial mammalian cells, suggesting the potential of these materials towards specific antimicrobial targeting for topical wound healing applications. The outcomes of this work show that facile tailorability of nanostructured surfaces may play a considerable role in controlling the biological activities of different nanomaterials.

Coinage metal coordination chemistry of stable primary, secondary and tertiary ferrocenylethyl-based phosphines.

PubMed

Azizpoor Fard, M; Rabiee Kenaree, A; Boyle, P D; Ragogna, P J; Gilroy, J B; Corrigan, J F

2016-02-21

Ferrocene-based phosphines constitute an important auxiliary ligand in inorganic chemistry. Utilizing the (ferrocenylethyl)phosphines (FcCH2CH2)3-nHnP (Fc = ferrocenyl; n = 2, 1; n = 1, 2; n = 0, 3) the synthesis of a series of coordination complexes [(FcCH2CH2)3-nHnPCuCl]4 (n = 2, 1-CuCl; n = 0, 3-CuCl), [(FcCH2CH2)2HPCuCl] (2-CuCl), {[(FcCH2CH2)H2P]2AgCl}2 (1-AgCl), [(FcCH2CH2)2HPAgCl] (2-AgCl), [(FcCH2CH2)3PAgCl]4 (3-AgCl), [(FcCH2CH2)3PM(OAc)]4 (M = Cu, 3-CuOAc M = Ag, 3-AgOAc), [(FcCH2CH2)3-nHnPAuCl] (n = 1, 2-AuCl; n = 0, 3-AuCl), via the reaction between the free phosphine and MX (M = Cu, Ag and Au; X = Cl, OAc), is described. The reaction between the respective phosphine with a suspension of metal-chloride or -acetate in a 1 : 1 ratio in THF at ambient temperature affords coordinated phosphine-coinage metal complexes. Varying structural motifs are observed in the solid state, as determined via single crystal X-ray analysis of 1-CuCl, 3-CuCl, 1-AgCl, 3-AgCl, 3-CuOAc, 3-AgOAc, 2-AuCl and 3-AuCl. Complexes 1-CuCl and 3-CuCl are tetrameric Cu(i) cubane-like structures with a Cu4Cl4 core, whereas silver complexes with primary and tertiary phosphine reveal two different structural types. The structure of 1-AgCl, unlike the rest, displays the coordination of two phosphines to each silver atom and shows a quadrangle defined by two Ag and two Cl atoms. In contrast, 3-AgCl is distorted from a cubane structure via elongation of one of the ClAg distances. 3-CuOAc and 3-AgOAc are isostructural with step-like cores, while complexes 2-AuCl and 3-AuCl reveal a linear geometry of a phosphine gold(i) chloride devoid of any aurophilic interactions. All of the complexes were characterized in solution by multinuclear (1)H, (13)C{(1)H} and (31)P NMR spectroscopic techniques; the redox chemistry of the series of complexes was examined using cyclic voltammetry. This class of complexes has been found to exhibit one reversible Fe(ii)/Fe(iii) oxidation couple, suggesting the

Porous AgPt@Pt Nanooctahedra as an Efficient Catalyst toward Formic Acid Oxidation with Predominant Dehydrogenation Pathway.

PubMed

Jiang, Xian; Yan, Xiaoxiao; Ren, Wangyu; Jia, Yufeng; Chen, Jianian; Sun, Dongmei; Xu, Lin; Tang, Yawen

2016-11-16

For direct formic acid fuel cells (DFAFCs), the dehydrogenation pathway is a desired reaction pathway, to boost the overall cell efficiency. Elaborate composition tuning and nanostructure engineering provide two promising strategies to design efficient electrocatalysts for DFAFCs. Herein, we present a facile synthesis of porous AgPt bimetallic nanooctahedra with enriched Pt surface (denoted as AgPt@Pt nanooctahedra) by a selective etching strategy. The smart integration of geometric and electronic effect confers a substantial enhancement of desired dehydrogenation pathway as well as electro-oxidation activity for the formic acid oxidation reaction (FAOR). We anticipate that the obtained nanocatalyst may hold great promises in fuel cell devices, and furthermore, the facile synthetic strategy demonstrated here can be extendable for the fabrication of other multicomponent nanoalloys with desirable morphologies and enhanced electrocatalytic performances.

Facility Management's Role in Organizational Sustainability

ERIC Educational Resources Information Center

Adams, Gregory K.

2013-01-01

Facility managers have questions about sustainability. How do an organization's physical facilities--its built environment--and the management of them, influence the sustainability of the organization or institution as a whole? How important is Facility Management (FM) to the overall sustainability profile of an organization? Facility managers…

Electron spin resonance of (CO 2 H)CH 2 CH 2 CH(CO 2 H) in irradiated glutaric acid

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

Horsfield, A.; Morton, J. R.; Whiffen, D. H.

It is concluded from electron spin resonance spectra that the radical (CO 2 H)CH 2 CH 2 CH(CO 2 H) remains trapped in a glutaric acid crystal after gamma -irradiation. This radical is found in two different conformations. Approximate hyperfine coupling constants are given for each, although exact interpretation is hindered by the overlapping of spectra. Reasons for the formation of the two forms of the radical are discussed.

Enhanced photocatalytic activity and structural stability by hybridizing Ag3PO4 nanospheres with graphene oxide sheets.

PubMed

Liang, Qinghua; Shi, Yao; Ma, Wangjing; Li, Zhi; Yang, Xinmin

2012-12-05

Graphene oxide (GO)-Ag(3)PO(4) nanocomposites synthesized through a facile solution approach via electrostatic interaction were investigated as excellent photocatalysts for the degradation of rhodamine B (RhB) under visible light irradiation. SEM and TEM observations indicate that Ag(3)PO(4) nanospheres of ~120 nm in diameter were well dispersed and anchored onto the exfoliated GO sheets. The characterizations of FTIR and Raman demonstrated the existence of strong charge interactions between GO sheets and Ag(3)PO(4) nanospheres. As compared to Ag(3)PO(4) nanospheres alone, the attachments of GO sheets led to a band gap narrowing (2.10 eV) and a strong absorbance in the near infrared region (NIR). The photoluminescence (PL) analysis indicates a more efficient separation of electron-hole pairs in the GO-Ag(3)PO(4) nanocomposites. Notably, the incorporation of GO sheets not only significantly enhances the photocatalytic activity but also improves the structural stability of Ag(3)PO(4). The positive synergistic effects between Ag(3)PO(4) nanospheres and GO sheets are proposed to contribute to the improved photocatalytic properties. A possible photocatalytic mechanism of the GO-Ag(3)PO(4) nanocomposites was assumed as well. The integration of these advantages enables such GO-Ag(3)PO(4) hybrid material to be a nice photocatalyst for broad applications in a sewage treatment system.

On the formation of the ·CH 2CH 2CH=NH 2+ distonic radical cation upon ionization of cyclopropylamine and allylamine

NASA Astrophysics Data System (ADS)

Nguyen, Minh Tho; Creve, Steven; Ha, Tae-Kyu

1998-08-01

Ab initio molecular orbital and density functional theory calculations have been applied to determine the relative stability of the cyclopropylamine 1 and allylamine (CH 2=CHCH 2NH 2+·2) radical cations and their isomers. It is confirmed that, upon ionization, 1 undergoes barrier-free ring-opening giving the distonic species ·CH 2CH 2CH=NH 2+3. 2 also rearranges by a 1,2-H-shift to the more stable 3 (by 70 kJ/mol) which is, however, less stable than the 1-aminopropene ion (CH 3-CH=CH-NH 2+·4) by 60 kJ/mol. The transition structure TS 2/3 lies 40 kJ/mol higher in energy than TS 3/4. Although QCISD and B3LYP calculations of isotropic hyperfine coupling constants agree reasonably with observed values, supporting the presence of the distonic 3 in ESR matrix experiments, the exclusive observation of 3, but not 4, is intriguing. This emphasizes the role of the matrix in stabilizing 3.

Synthesis of [{AgO2CCH2OMe(PPh3)} n ] and theoretical study of its use in focused electron beam induced deposition.

PubMed

Tamuliene, Jelena; Noll, Julian; Frenzel, Peter; Rüffer, Tobias; Jakob, Alexander; Walfort, Bernhard; Lang, Heinrich

2017-01-01

The synthesis, chemical and physical properties of [{AgO 2 CCH 2 OMe} n ] ( 1 ) and [{AgO 2 CCH 2 OMe(PPh 3 )} n ] ( 2 ) are reported. Consecutive reaction of AgNO 3 with HO 2 CCH 2 OMe gave 1 , which upon treatment with PPh 3 produced 2 . Coordination compound 2 forms a 1D coordination polymer in the solid state as evidenced by single crystal X-ray structure analysis. The coordination geometry at Ag + is of the [3 + 1] type, whereby the carboxylate anions act as bridging ligands. The formation of PPh 3 -Ag(I) coordinative bonds results in distorted T-shaped AgPO 2 units, which are stabilized further by an additional O-Ag dative bond. TG and TG-MS measurements show that 1 and 2 decompose at 190-250 °C ( 1 ) and 260-300 °C ( 2 ) via decarboxylation, involving Ag-P ( 2 ), C-C and C-O bond cleavages to give elemental silver as confirmed by PXRD studies. In order to verify if polymeric 2 is suitable as a FEBID precursor for silver deposition, its vapor pressure was determined ( p 170 °C = 5.318 mbar, ∆H vap = 126.1 kJ mol -1 ), evincing little volatility. Also EI and ESI mass spectrometric studies were carried out. The dissociation of the silver(I) compound 2 under typical electron-driven FEBID conditions was studied by DFT (B3LYP) calculations on monomeric [AgO 2 CCH 2 OMe(PPh 3 )]. At an energy of the secondary electrons up to 0.8 eV elimination of PPh 3 occurs, giving Ag + and O 2 CCH 2 OMe - . Likewise, by release of PPh 3 from [AgO 2 CCH 2 OMe(PPh 3 )] the fragment [AgO 2 CCH 2 OMe] - is formed from which Ag + and O 2 CCH 2 OMe - is generated, further following the first fragmentation route. However, at 1.3 eV the initial step is decarboxylation giving [AgCH 2 OMe(PPh 3 )], followed by Ag-P and Ag-C bond cleavages.

Ionic liquids-water interfacial preparation of triangular Ag nanoplates and their shape-dependent antibacterial activity.

PubMed

Lu, Weiwei; Yao, Kaisheng; Wang, Jianji; Yuan, Jiongliang

2015-01-01

As a class of green and designable solvents, ionic liquids (ILs) have been used extensively in inorganic synthesis. In those schemes, ILs were usually used as reaction media to replace water and organic solvents, and/or used as stabilizer and capping agents to act like an amphiphilic molecule or polymer. However, the unique properties of ILs were not fully utilized in the area of material preparation. In this study, a new protocol of "ILs-water interfacial synthesis" was developed and used for the preparation of Ag nanomaterials. Taking the advantage of tunable property of ILs-water interface, Ag nanomaterials with different morphology such as triangular nanoplates, polygonal nanoplates, and nanoparticles could be facilely obtained. Growth mechanism of the triangular Ag nanoplates has been investigated from structural characterization and molecular dynamics (MD) simulation. It was shown that growth of the nanoplates was under kinetic control mainly due to high viscosity and ionicity of the ILs. Furthermore, the antimicrobial performance of these Ag samples was tested to study the influence of shape of the Ag nanomaterials on the antimicrobial activity and the related antimicrobial mechanism. The results suggested that the efficient antimicrobial activity of the triangular Ag nanoplates was ascribed to their sharp corners and edges and large areas of active (111) crystal plane, which leads to the higher amount of leaching Ag(+) ion. Copyright © 2014 Elsevier Inc. All rights reserved.

Rate Constants for the Reactions of OH with CH(sub 3)Cl, CH(sub 2) C1(sub 2), CHC1(sub 3)and CH(sub 3)Br

NASA Technical Reports Server (NTRS)

Hsu, H-J.; DeMore, W.

1994-01-01

Rate constants for the reactions of OH with CH3C1, CH2Cl2, CHCl3 and CH3Br have been measured by a relative rate technique in which the reaction rate of each compound was compared to that of HFC-152a (CH3CHF2)and for CH2Cl2, HFC-161 (CH3CH2F).

Fabrication of PANI/Ag/AgCl/ITO-PET Flexible Film and Its Crystallinity and Electrical Properties

NASA Astrophysics Data System (ADS)

Diantoro, M.; Rohmiani, F.; Mustikasari, A. A.; Sunaryono

2018-05-01

Abstrak. PANI as one of the conductive polymers which have been widely using in electronics or storage devices such as a supercapacitor. PANI has recently become an option because of its potential for a broad area of application. Protonation or introduce a dopant can control the electrical properties of PANI. However, researcher facing a disadvantage since PANI also active in acidic conditions. To control the conductivity and the stability in an acidic environment, the researcher has introduced Ag/AgCl to PANI. We report the synthesis and analyses of silver nanoparticles (AgNPs), PANI, and PANI/Ag/AgCl/ITO-PET films. PANI was synthesized by chemical polymerization, while AgNPs were synthesized via a reductive chemical method using NaBH4 as an AgNO3 reductor. The resulting PANI was characterized using FTIR to determine the functional group, while to obtain the purity of the Ag phase was checked by using XRD. The preparation of PANi/Ag/AgCl solution was carried out by mixing method with the variation of the mass of AgNO3. The precipitate was carried out by using ITOPET substrate. PANI/Ag/AgCl/ITO-PET films were characterized by using FTIR, XRD, SEMEDX, and capacitance meters. It has was found that crystallinity increases with the addition of Ag films to PANI/Ag/AgCl/ITO-PET. The crystallinity reached 29.85 %. It was also revealed that the dielectric constant decreased with increasing Ag in PANi/Ag/AgCl/ITO-PET films.

Reducing Strength Prevailing at Root Surface of Plants Promotes Reduction of Ag+ and Generation of Ag0/Ag2O Nanoparticles Exogenously in Aqueous Phase

PubMed Central

Pardha-Saradhi, Peddisetty; Yamal, Gupta; Peddisetty, Tanuj; Sharmila, Peddisetty; Nagar, Shilpi; Singh, Jyoti; Nagarajan, Rajamani; Rao, Kottapalli S.

2014-01-01

Potential of root system of plants from wide range of families to effectively reduce membrane impermeable ferricyanide to ferrocyanide and blue coloured 2,6-dichlorophenol indophenol (DCPIP) to colourless DCPIPH2 both under non-sterile and sterile conditions, revealed prevalence of immense reducing strength at root surface. As generation of silver nanoparticles (NPs) from Ag+ involves reduction, present investigations were carried to evaluate if reducing strength prevailing at surface of root system can be exploited for reduction of Ag+ and exogenous generation of silver-NPs. Root system of intact plants of 16 species from 11 diverse families of angiosperms turned clear colorless AgNO3 solutions, turbid brown. Absorption spectra of these turbid brown solutions showed silver-NPs specific surface plasmon resonance peak. Transmission electron microscope coupled with energy dispersive X-ray confirmed the presence of distinct NPs in the range of 5–50 nm containing Ag. Selected area electron diffraction and powder X-ray diffraction patterns of the silver NPs showed Bragg reflections, characteristic of crystalline face-centered cubic structure of Ag0 and cubic structure of Ag2O. Root system of intact plants raised under sterile conditions also generated Ag0/Ag2O-NPs under strict sterile conditions in a manner similar to that recorded under non-sterile conditions. This revealed the inbuilt potential of root system to generate Ag0/Ag2O-NPs independent of any microorganism. Roots of intact plants reduced triphenyltetrazolium to triphenylformazon and impermeable ferricyanide to ferrocyanide, suggesting involvement of plasma membrane bound dehydrogenases in reduction of Ag+ and formation of Ag0/Ag2O-NPs. Root enzyme extract reduced triphenyltetrazolium to triphenylformazon and Ag+ to Ag0 in presence of NADH, clearly establishing potential of dehydrogenases to reduce Ag+ to Ag0, which generate Ag0/Ag2O-NPs. Findings presented in this manuscript put forth a novel, simple

Low-Temperature Hydrocarbon Photochemistry: CH3 + CH3 Recombination in Giant Planet Atmospheres

NASA Technical Reports Server (NTRS)

Smith, Gregory P.; Huestis, David L.

2002-01-01

Planetary emissions of the methyl radical CH3 were observed for the first time in 1998 on Saturn and Neptune by the ISO (Infrared Space Observatory) mission satellite. CH3 is produced by VUV photolysis of CH4 and is the key photochemical intermediate leading complex organic molecules on the giant planets and moons. The CH3 emissions from Saturn were unexpectedly weak. A suggested remedy is to increase the rate of the recombination reaction CH3 + CH3 + H2 --> C2H6 + H2 at 140 K to a value at least 10 times that measured at room temperature in rare gases, but within the range of disagreeing theoretical expressions at low temperature. We are performing laboratory experiments at low temperature and very low pressure. The experiments are supported by RRKM theoretical modeling that is calibrated using the extensive combustion literature.

Structural and Solar Cell Properties of a Ag-Containing Cu2ZnSnS4 Thin Film Derived from Spray Pyrolysis.

PubMed

Nguyen, Thi Hiep; Kawaguchi, Takato; Chantana, Jakapan; Minemoto, Takashi; Harada, Takashi; Nakanishi, Shuji; Ikeda, Shigeru

2018-02-14

A silver (Ag)-incorporated kesterite Cu 2 ZnSnS 4 (CZTS) thin film was fabricated by a facile spray pyrolysis method. Crystallographic analyses indicated successful incorporation of various amounts of Ag up to a Ag/(Ag + Cu) ratio of ca. 0.1 into the crystal lattice of CZTS in a homogeneous manner without formation of other impurity compounds. From the results of morphological investigations, Ag-incorporated films had larger crystal grains than the CZTS film. The sample with a relatively low Ag content (Ag/(Ag + Cu) of ca. 0.02) had a compact morphology without appreciable voids and pinholes. However, an increase in the Ag content in the CZTS film (Ag/(Ag + Cu) ca. 0.10) induced the formation of a large number of pinholes. As can be expected from these morphological properties, the best sunlight conversion efficiency was obtained by the solar cell based on the film with Ag/(Ag + Cu) of ca. 0.02. Electrostructural analyses of the devices suggested that the Ag-incorporated film in the device achieved reduction in the amounts of unfavorable copper on zinc antisite defects compared to the bare CZTS film. Moreover, the use of a Ag-incorporated film improved band alignment at the CdS(buffer)-CZTS interface. These alterations should also contribute to enhancement of device properties.

Unusual reaction paths of SN2 nucleophile substitution reactions CH4 + H- → CH4 + H- and CH4 + F- → CH3F + H-: Quantum chemical calculations

NASA Astrophysics Data System (ADS)

Minyaev, Ruslan M.; Quapp, Wolfgang; Schmidt, Benjamin; Getmanskii, Ilya V.; Koval, Vitaliy V.

2013-11-01

Quantum chemical (CCSD(full)/6-311++G(3df,3pd), CCSD(T)(full)/6-311++G(3df,3pd)) and density function theory (B3LYP/6-311++G(3df,3pd)) calculations were performed for the SN2 nucleophile substitution reactions CH4 + H- → CH4 + H- and CH4 + F- → CH3F + H-. The calculated gradient reaction pathways for both reactions have an unusual behavior. An unusual stationary point of index 2 lies on the gradient reaction path. Using Newton trajectories for the reaction path, we can detect VRI point at which the reaction path branches.

Apple fruit acidity is genetically diversified by natural variations in three hierarchical epistatic genes MdSAUR37, MdPP2CH and MdALMTII.

PubMed

Jia, Dongjie; Shen, Fei; Wang, Yi; Wu, Ting; Xu, Xuefeng; Zhang, Xinzhong; Han, Zhenhai

2018-05-11

Many efforts have been made to map quantitative trait loci (QTLs) to facilitate practical marker-assisted selection (MAS) in plants. In the present study, we identified four genome-wide major QTLs responsible for apple fruit acidity by MapQTL and BSA-seq analyses using two independent pedigree-based populations. Candidate genes were screened in major QTL regions, and three functional gene markers, including a non-synonymous A/G single nucleotide polymorphism (SNP) in the coding region of MdPP2CH, a 36-bp insertion in the promoter of MdSAUR37, and a previously reported SNP in MdALMTII, were validated to influence the malate content of apple fruits. In addition, MdPP2CH inactivated three vacuolar H + -ATPases (MdVHA-A3, MdVHA-B2 and MdVHA-D2) and one aluminium-activated malate transporter (MdALMTII) via dephosphorylation and negatively influenced fruit malate accumulation. The dephosphotase activity of MdPP2CH was suppressed by MdSAUR37, which implied a higher hierarchy of genetic interaction. Therefore, the MdSAUR37/MdPP2CH/MdALMTII chain cascaded hierarchical epistatic genetic effects to precisely determine apple fruit malate content. An A/G SNP (-1010) on MdMYB44 promoter region from a major QTL (qtl08.1) was closely associated with fruit malate content. The predicted phenotype values (PPVs) were estimated using the tentative genotype values of the gene markers, and the PPVs were significantly correlated with the observed phenotype values. Our findings provide an insight into plant genome-based selection in apples and will aid in conducting research to understand the physiological fundamentals of quantitative genetics. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Evaluation of the chelating performance of biopolyelectrolyte green complexes (NIBPEGCs) for wastewater treatment from the metal finishing industry.

PubMed

López-Maldonado, Eduardo A; Zavala García, Oscar Gabriel; Escobedo, Kevin Cruz; Oropeza-Guzman, Mercedes T

2017-08-05

In this paper nonstoichiometric interbiopolyelectrolyte green complexes (NIBPEGCs) were prepared using chitosan (Ch), alginate (AG) and poly(acrylic acid)(PAA). They are proposed as innovative formulations (polyelectrolytes and chelating agents) suitable for the elimination heavy metals contained in wastewater. This application may represent an integral solution for industries rejecting solid and aqueous metallic materials; however, it has not been previously reported. NIBPEGCs physicochemical performance was evaluated based on pH, particle size, surface charge, isoelectric point, dose, coagulation-flocculation kinetics and chemical affinity with seven metal ions. The experimental results showed that NIBPEGCs composed by AG/Ch and PAA/Chitosan have all the three complementary functions: chemical affinity, electrostatic interaction and particle entrapment anticipating more simple operation units to remove heavy metals. Complexes of AG/Ch (negative) were higher performance in removing heavy metals, with a dose window (150-180mg/L), lower dose of 410mg/L PAA/Ch (negative). Investigation of chelating performances of NIBPEGCs show that the efficiency of metal removal is: Ca˃Cr˃Cu˃Pb˃Ni˃Zn˃Cd. Transmittance vs time profiles, metals and zeta potential analysis showed that chelation capacity is the crucial factor to ensure metallic species removal, followed by physical entrapment of the metallic colloids. Integrating all presented results allow to sustain the development of excellent metals removal formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Fabrication of Ag nanoparticle catalyst supported on graphene for effective H2O2 nonenzymatic detection powered by chemical energy

NASA Astrophysics Data System (ADS)

Zhang, Hulin; Xie, Yuhang; Zhang, Shangjie; Wen, Yige; Chen, Changyong; Ye, Wenhao; Lin, Yuan

2017-06-01

Ag nanoparticles/graphene nanosheets (Ag NPs/GNs) have been fabricated using graphene nanosheets (GNs) as frames for the growth of Ag nanoparticles (Ag NPs). The graphene nanostructures adsorbed with a large number of Ag NPs and were synthesized via a facile redox reaction. The prepared nanocatalysts were characterized using x-ray diffraction, Raman spectroscopy, field electron scanning electron microscopy and transmission electron microscopy. The electrochemical activity of the Ag NPs/GNs for the detection of H2O2 was explored using cyclic voltammetry and chronoamperometry, indicating that the Ag NPs/GNs can remarkably facilitate H2O2 redox in phosphate buffer solution. Further comparative investigations show that the as-prepared Ag nanocatalysts exhibit a wide linear range, a high response, and a short response time for H2O2 detection. To further exploit the practical applications in H2O2 detection, the homemade electrochemical cells were employed to power the Ag NPs/GNs electrode sensor by chemical energy without external power sources. The results expand the applications of the graphene-based sensors and propose a feasible self-powered biochemical sensing approach independent of conventional power sources.

Structural and superionic properties of Ag+-rich ternary phases within the AgI-MI2 systems

NASA Astrophysics Data System (ADS)

Hull, S.; Keen, D. A.; Berastegui, P.

2002-12-01

The effects of temperature on the crystal structure and ionic conductivity of the compounds Ag2CdI4, Ag2ZnI4 and Ag3SnI5 have been investigated by powder diffraction and impedance spectroscopy techniques. varepsilon-Ag2CdI4 adopts a tetragonal crystal structure under ambient conditions and abrupt increases in the ionic conductivity are observed at 407(2), 447(3) and 532(4) K, consistent with the sequence of transitions varepsilon-Ag2CdI 4 rightarrow beta-Ag2CdI 4 + beta-AgI + CdI2 rightarrow alpha-AgI + CdI2 rightarrow alpha-Ag2CdI4. Hexagonal beta-Ag2CdI4 is metastable at ambient temperature. The ambient-temperature beta phase of Ag2ZnI4 is orthorhombic and the structures of beta-Ag2CdI4 and beta-Ag2ZnI4 can, respectively, be considered as ordered derivatives of the wurtzite (beta) and zincblende (gamma) phases of AgI. On heating Ag2ZnI4, there is a 12-fold increase in ionic conductivity at 481(1) K and a further eightfold increase at 542(3) K. These changes result from decomposition of beta-Ag2ZnI4 into alpha-AgI + ZnI2, followed by the appearance of superionic alpha-Ag2ZnI4 at the higher temperature. The hexagonal crystal structure of alpha-Ag2ZnI4 is a dynamically disordered counterpart to the beta modification. Ag3SnI5 is only stable at temperatures in excess of 370(3) K and possesses a relatively high ionic conductivity (sigma approx 0.19Omega-1 cm-1 at 420 K) due to dynamic disorder of the Ag+ and Sn2+ within a cubic close packed I- sublattice. The implications of these findings for the wider issue of high ionic conductivity in AgI-MI2 compounds is discussed, with reference to recently published studies of Ag4PbI6 and Ag2HgI4 and new data for the temperature dependence of the ionic conductivity of the latter compound.

Reflected shock tube studies of high-temperature rate constants for OH + CH4 --> CH3 + H2O and CH3 + NO2 --> CH3O + NO.

PubMed

Srinivasan, N K; Su, M-C; Sutherland, J W; Michael, J V

2005-03-10

The reflected shock tube technique with multipass absorption spectrometric detection of OH radicals at 308 nm has been used to study the reactions OH + CH(4) --> CH(3) + H(2)O and CH(3) + NO(2) --> CH(3)O + NO. Over the temperature range 840-2025 K, the rate constants for the first reaction can be represented by the Arrhenius expression k = (9.52 +/- 1.62) x 10(-11) exp[(-4134 +/- 222 K)/T] cm(3) molecule(-1) s(-1). Since this reaction is important in both combustion and atmospheric chemistry, there have been many prior investigations with a variety of techniques. The present results extend the temperature range by 500 K and have been combined with the most accurate earlier studies to derive an evaluation over the extended temperature range 195-2025 K. A three-parameter expression describes the rate behavior over this temperature range, k = (1.66 x 10(-18))T(2.182) exp[(-1231 K)/T] cm(3) molecule(-1) s(-1). Previous theoretical studies are discussed, and the present evaluation is compared to earlier theoretical estimates. Since CH(3) radicals are a product of the reaction and could cause secondary perturbations in rate constant determinations, the second reaction was studied by OH radical production from the fast reactions CH(3)O --> CH(2)O + H and H + NO(2) --> OH + NO. The measured rate constant is 2.26 x 10(-11) cm(3) molecule(-1) s(-1) and is not dependent on temperature from 233 to 1700 K within experimental error.

BOREAS TGB-1 NSA CH4 and CO2 Chamber Flux Data

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Crill, Patrick; Varner, Ruth K.

2000-01-01

The BOREAS TGB-1 team made methane (CH4) and carbon dioxide (CO2) dark chamber flux measurements at the NSA-OJP, NSA-OBS, NSA-BP, and NSA-YJP sites from 16-May-1994 through 13-Sep-1994. Gas samples were extracted approximately every 7 days from dark chambers and analyzed at the NSA lab facility. The data are provided in tabular ASCII files.

Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

NASA Astrophysics Data System (ADS)

Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.

2015-09-01

We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

Total cross sections of electron scattering by molecules NF3, PF3, N(CH3)3, P(CH3)3, NH(CH3)2, PH(CH3)2, NH2CH3 and PH2CH3 at 30-5000 eV

NASA Astrophysics Data System (ADS)

Shi, D. H.; Sun, J. F.; Zhu, Z. L.; Liu, Y. F.

2010-04-01

Total cross sections of electron scattering by eight molecules NF3, PF3, N(CH3)3, P(CH3)3, NH(CH3)2, PH(CH3)2, NH2CH3 and PH2CH3, which have some structural similarities, are calculated at the Hartree-Fork level by the modified additivity rule approach [D.H. Shi, J.F. Sun, Z.L. Zhu, H. Ma, Y.F. Liu, Eur. Phys. J. D 45, 253 (2007); D.H. Shi, J.F. Sun, Y.F. Liu, Z.L. Zhu, X.D. Yang, Chin. Opt. Lett. 4, 192 (2006)]. The modified additivity rule approach takes into considerations that the contributions of the geometric shielding effect vary as the energy of incident electrons, the dimension of target molecule, the number of electrons in the molecule and the number of atoms constituting the molecule. The present investigations cover the impact energy range from 30 to 5000 eV. The quantitative total cross sections are compared with those obtained by experiments and other theories. Excellent agreement is observed even at energies of several tens of eV. It shows that the modified additivity rule approach is applicable to carry out the total cross section calculations of electron scattering by these molecules at intermediate and high energies, in particular over the energy range above 80 eV or so. It proves that the microscopic molecular properties, such as the geometrical size of the target and the number of atoms constituting the molecule, are of crucial importance in the TCS calculations. The new results for PH(CH3)2 and PH2CH3 are also presented at energies from 30 to 5000 eV, although no experimental and theoretical data are available for comparison. In the present calculations, the atoms are still represented by the spherical complex optical potential, which is composed of static, exchange, polarization and absorption terms.

Ag/AgBr-loaded mesoporous silica for rapid sterilization and promotion of wound healing.

PubMed

Jin, Chen; Liu, Xiangmei; Tan, Lei; Cui, Zhenduo; Yang, Xianjin; Zheng, Yufeng; Yeung, Kelvin Wai Kwok; Chu, Paul K; Wu, Shuilin

2018-06-25

Bacterial infection is a major concern during the wound healing process. Herein, Ag/AgBr-loaded mesoporous silica nanoparticles (Ag/AgBr/MSNs) are designed to harvest visible light for rapid sterilization and acceleration of wound healing. The Ag/AgBr nanostructure has remarkable photocatalysis ability due to the critical factor that it can generate electron-hole pairs easily after light absorption. This remarkable photocatalytic effect enhances the antibacterial activity by producing reactive oxygen species (ROS). The bacterial killing efficiency of Ag/AgBr/MSNs is 95.62% and 99.99% against Staphylococcus aureus and Escherichia coli, respectively, within 15 min under simulated solar light irradiation due to the generation of ROS. Furthermore, the composites can arrest the bacterial growth and damage the bacterial membrane through electrostatic interaction. The gradual release of Ag+ not only prevents bacterial infection with good long-term effectiveness but also stimulates the immune function to produce a large number of white blood cells and neutrophils, which favors the promotion of the wound healing process. This platform provides an effective strategy to prevent bacterial infection during wound healing.

Electron driven processes in sulphur containing compounds CH3SCH3 and CH3SSCH3

NASA Astrophysics Data System (ADS)

Kopyra, Janina; Władziński, Jakub

2015-06-01

Dissociative electron attachment to gas phase dimethyl sulphide (CH3SCH3) and dimethyl disulphide (CH3SSCH3) has been studied by means of a crossed beams apparatus. Cleavage of the C-S bond within CH3SCH3 and the S-S bond within CH3SSCH3 is observed within a resonance in the energy range below 2 eV and visible preferentially via the appearance of the fragment CH2S-. The striking finding is that the intensity of CH2S- generated from CH3SSCH3 is more than two orders of magnitude higher than the intensity of the respective anionic fragment generated from CH3SCH3. Our results clearly demonstrate that the CH3SSCH3 molecule, which contains disulphide bridge is substantially more sensitive towards electron attachment resulting mainly in dissociation along the S-S bridge.

Scaled Hartree-Fock force field calculations for organothallium compounds: Normal-mode analysis for TlCH sub 3 Tl(CH sub 3 ) sub 2 sup + , Tl(CH sub 3 ) sub 3 , Tl(CH sub 3 ) sub 2 Br, and Tl(CH sub 3 ) sub 4 sup minus

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

Schwerdtfeger, P.; Bowmaker, G.A.; Boyd, P.D.W.

1990-02-01

In a recent paper we presented Hartree-Fock (HF) calculations for aliphatic organothallium compounds. The diagonal HF force constants obtained from a Fletcher-Powell geometry optimization are now used for a normal-mode analysis of TlCH{sub 3}, Tl(CH{sub 3}){sub 2}{sup +}, Tl(CH{sub 3}){sub 3}, Tl(CH{sub 3}){sub 2}Br, and Tl(CH{sub 3}){sub 4}{sup {minus}}. In order to calculate frequencies comparable to experimental values, the HF force field has been scaled by using scaling factors obtained from experimental infrared and Raman measurements on Tl(CH{sub 3}){sub 2}{sup +} and TlBr. The vibrational spectra of Tl(CH{sub 3}){sub 2}{sup +} were remeasured (infrared and Raman) in order to obtainmore » an accurate force field. Predictions are made for the vibrational spectrum of the as yet undetected TlCH{sub 3} molecule. Experimental infrared and Raman results for Tl(CH{sub 3}){sub 3} compare reasonably well with our calculated frequencies. Relativistic and correlation effects are analyzed for the vibrational frequencies of Tl(CH{sub 3}){sub 2}{sup +}.« less

Florida Educational Facilities, 1999.

ERIC Educational Resources Information Center

Florida State Dept. of Education, Tallahassee. Office of Educational Facilities.

This publication describes Florida school and community college facilities completed in 1999, including photographs and floor plans. The facilities profiled are: Buchholz High School (Alachua County); Gator Run Elementary School (Broward); Corkscrew Elementary School (Collier); The 500 Role Models Academy of Excellence (Miami-Dade); Caribbean…

Florida Educational Facilities, 2000.

ERIC Educational Resources Information Center

Florida State Dept. of Education, Tallahassee. Office of Educational Facilities.

This publication describes Florida school and community college facilities completed in 2000, including photographs and floor plans. The facilities profiled are:J. R. Arnold High School (Bay County); Falcon Cove Middle School (Broward); Floranada Elementary School (Broward); Lyons Creek Middle School (Broward); Parkside Elementary School…

CO2 and CH4 Surface Flux, Soil Profile Concentrations, and Stable Isotope Composition, Barrow, Alaska, 2012-2013

DOE Data Explorer

Curtis, J.B.; Vaughn, L.S.; Torn, M.S.; Conrad, M.S.; Chafe, O.; Bill, M.

2015-12-31

In August-October 2012 and June-October 2013, co-located measurements were made of surface CH4 and CO2 flux, soil pore space concentrations and stable isotope compositions of CH4 and CO2, and subsurface temperature and soil moisture. Measurements were made in intensive study site 1 areas A, B, and C, and from the site 0 and AB transects, from high-centered, flat-centered, and low-centered polygons, from the center, edge, and trough of each polygon.

H2O2 rejuvenation-mediated synthesis of stable mixed-morphology Ag3PO4 photocatalysts.

PubMed

Agbe, Henry; Raza, Nadeem; Dodoo-Arhin, David; Chauhan, Aditya; Kumar, Ramachandran Vasant

2018-04-01

Ag 3 PO 4 photocatalyst has attracted interest of the scientific community in recent times due to its reported high efficiency for water oxidation and dye degradation. However, Ag 3 PO 4 photo-corrodes if electron accepter such as AgNO 3 is not used as scavenger. Synthesis of efficient Ag 3 PO 4 followed by a simple protocol for regeneration of the photocatalyst is therefore a prerequisite for practical application. Herein, we present a facile method for the synthesis of a highly efficient Ag 3 PO 4 , whose photocatalytic efficiency was demonstrated using 3 different organic dyes: Methylene Blue (MB), Methyl orange (MO) and Rhodamine B (RhB) organic dyes for degradation tests. Approximately, 19 % of Ag 3 PO 4 is converted to Ag 0 after 4.30 hours of continuous UV-Vis irradiation in presence of MB organic dye. We have shown that the Ag/Ag 3 PO 4 composite can be rejuvenated by a simple chemical oxidation step after several cycles of photocatalysis tests. At an optimal pH of 6.5, a mixture of cubic, rhombic dodecahedron, nanosphere and nanocrystals morphologies of the photocatalyst was formed. H 2 O 2 served as the chemical oxidant to re-insert the surface metallic Ag into the Ag 3 PO 4 photocatalyst but also as the agent that can control morphology of the regenerated as-prepared photocatalyst without the need for any other morphology controlling Agent (MCA). Surprisingly, the as- regenerated Ag 3 PO 4 was found to have higher photocatalytic reactivity than the freshly made material and superior at least 17 times in comparison with the conventional Degussa TiO 2 , and some of TiO 2 composites tested in this work.

Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

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

Kumaran, R.; Alagar, M.; Dinesh Kumar, S.

We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDFmore » matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.« less

CH-TRU Waste Content Codes

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

Washington TRU Solutions LLC

2008-01-16

The CH-TRU Waste Content Codes (CH-TRUCON) document describes the inventory of the U.S. Department of Energy (DOE) CH-TRU waste within the transportation parameters specified by the Contact-Handled Transuranic Waste Authorized Methods for Payload Control (CH-TRAMPAC). The CH-TRAMPAC defines the allowable payload for the Transuranic Package Transporter-II (TRUPACT-II) and HalfPACT packagings. This document is a catalog of TRUPACT-II and HalfPACT authorized contents and a description of the methods utilized to demonstrate compliance with the CH-TRAMPAC. A summary of currently approved content codes by site is presented in Table 1. The CH-TRAMPAC describes "shipping categories" that are assigned to each payload container.more » Multiple shipping categories may be assigned to a single content code. A summary of approved content codes and corresponding shipping categories is provided in Table 2, which consists of Tables 2A, 2B, and 2C. Table 2A provides a summary of approved content codes and corresponding shipping categories for the "General Case," which reflects the assumption of a 60-day shipping period as described in the CH-TRAMPAC and Appendix 3.4 of the CH-TRU Payload Appendices. For shipments to be completed within an approximately 1,000-mile radius, a shorter shipping period of 20 days is applicable as described in the CH-TRAMPAC and Appendix 3.5 of the CH-TRU Payload Appendices. For shipments to WIPP from Los Alamos National Laboratory (LANL), Nevada Test Site, and Rocky Flats Environmental Technology Site, a 20-day shipping period is applicable. Table 2B provides a summary of approved content codes and corresponding shipping categories for "Close-Proximity Shipments" (20-day shipping period). For shipments implementing the controls specified in the CH-TRAMPAC and Appendix 3.6 of the CH-TRU Payload Appendices, a 10-day shipping period is applicable. Table 2C provides a summary of approved content codes and corresponding shipping categories for "Controlled

Preparation, characterization, and antibacterial activity of NiFe2O4/PAMA/Ag-TiO2 nanocomposite

NASA Astrophysics Data System (ADS)

Allafchian, Alireza; Jalali, Seyed Amir Hossein; Bahramian, Hamid; Ahmadvand, Hossein

2016-04-01

We have described a facile fabrication of silver deposited on the TiO2, Poly Acrylonitrile Co Maleic Anhydride (PAMA) polymer and nickel ferrite composite (NiFe2O4/PAMA/Ag-TiO2) through a three-step procedure. A pre-synthesized NiFe2O4 was first coated with PAMA polymer and then Ag-TiO2 was deposited on the surface of PAMA polymer shell. After the characterization of this three-component composite by various techniques, such as FTIR, XRD, FESEM, BET, TEM and VSM, it was impregnated in standard antibiotic discs. The antibacterial activity of NiFe2O4/PAMA/Ag-TiO2 nanocomposite was investigated against some gram positive and gram negative bacteria by employing disc diffusion assay and then compared with that of naked NiFe2O4, NiFe2O4/Ag, AgNPs and NiFe2O4/PAMA. The results demonstrated that the AgNPs, when embedded in TiO2 and combined with NiFe2O4/PAMA, became an excellent antibacterial agent. The NiFe2O4/PAMA/Ag-TiO2 nanocomposite could be readily separated from water solution after the disinfection process by applying an external magnetic field.

Improved galvanic replacement growth of Ag microstructures on Cu micro-grid for enhanced SERS detection of organic molecules.

PubMed

Guo, Tian-Long; Li, Ji-Guang; Sun, Xudong; Sakka, Yoshio

2016-04-01

Galvanic growth of Ag nano/micro-structures on Cu micro-grid was systematically studied for surface-enhanced Raman scattering (SERS) applications. Detailed characterizations via FE-SEM and HR-TEM showed that processing parameters, (reaction time, Ag(+) concentration, and PVP addition) all substantially affect thermodynamics/kinetics of the replacement reaction to yield substrates of significantly different microstructures/homogeneities and thus varied SERS performances (sensitivity, enhancement factor, and reproducibility) of the Ag substrates in the detection of R6G analyte. PVP as an additive was shown to notably alter nucleation/growth behaviors of the Ag crystals and promote the deposition of dense and uniform Ag films of nearly monodisperse polyhedrons/nanoplates through suppressing dendrites crystallization. Under optimized synthesis (50mM of Ag(+), 30s of reaction, and 700 wt.% of PVP), Ag substrates exhibiting a high Raman signal enhancement factor of ~1.1 × 10(6) and a low relative standard deviation of ~0.13 in the repeated detection of 10 μM R6G were obtained. The facile deposition and excellent performance reported in this work may allow the Ag microstructures to find wider SERS applications. Moreover, growth mechanisms of the different Ag nano/micro-structures were discussed based on extensive FE-SEM and HR-TEM analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of exposure to silver nanoparticles in a manufacturing facility

NASA Astrophysics Data System (ADS)

Park, Junsu; Kwak, Byoung Kyu; Bae, Eunjoo; Lee, Jeongjin; Kim, Younghun; Choi, Kyunghee; Yi, Jongheop

2009-10-01

An assessment of the extent of exposure to nanomaterials in the workplace will be helpful in improving the occupational safety of workers. It is essential that the exposure data in the workplace are concerned with risk management to evaluate and reduce worker exposure. In a manufacturing facility dealing with nanomaterials, some exposure data for gas-phase reactions are available, but much less information is available regarding liquid-phase reactions. Although the potential for inhaling nanomaterials in a liquid-phase process is less than that for gas-phase, the risks of exposure during wet-chemistry processes are not negligible. In this study, we monitored and analyzed the exposure characteristics of silver nanoparticles during a liquid-phase process in a commercial production facility. Based on the measured exposure data, the source of Ag nanoparticles emitted during the production processes was indentified and a mechanism for the growth of Ag nanoparticle released is proposed. The data reported in this study could be used to establish occupational safety guidelines in the nanotechnology workplace, especially in a liquid-phase production facility.

Advanced surface characterization of silver nanocluster segregation in Ag-TiCN bioactive coatings by RBS, GDOES, and ARXPS.

PubMed

Escobar Galindo, R; Manninen, N K; Palacio, C; Carvalho, S

2013-07-01

Surface modification by means of wear protective and antibacterial coatings represents, nowadays, a crucial challenge in the biomaterials field in order to enhance the lifetime of bio-devices. It is possible to tailor the properties of the material by using an appropriate combination of high wear resistance (e.g., nitride or carbide coatings) and biocide agents (e.g., noble metals as silver) to fulfill its final application. This behavior is controlled at last by the outmost surface of the coating. Therefore, the analytical characterization of these new materials requires high-resolution analytical techniques able to provide information about surface and depth composition down to the nanometric level. Among these techniques are Rutherford backscattering spectrometry (RBS), glow discharge optical emission spectroscopy (GDOES), and angle resolved X-ray photoelectron spectroscopy (ARXPS). In this work, we present a comparative RBS-GDOES-ARXPS study of the surface characterization of Ag-TiCN coatings with Ag/Ti atomic ratios varying from 0 to 1.49, deposited at room temperature and 200 °C. RBS analysis allowed a precise quantification of the silver content along the coating with a non-uniform Ag depth distribution for the samples with higher Ag content. GDOES surface profiling revealed that the samples with higher Ag content as well as the samples deposited at 200 °C showed an ultrathin (1-10 nm) Ag-rich layer on the coating surface followed by a silver depletion zone (20-30 nm), being the thickness of both layers enhanced with Ag content and deposition temperature. ARXPS analysis confirmed these observations after applying general algorithm involving regularization in addition to singular value decomposition techniques to obtain the concentration depth profiles. Finally, ARXPS measurements were used to provide further information on the surface morphology of the samples obtaining an excellent agreement with SEM observations when a growth model of silver islands with

Atmospheric CH4 oxidation by Arctic permafrost and mineral cryosols as a function of water saturation and temperature.

PubMed

Stackhouse, B; Lau, M C Y; Vishnivetskaya, T; Burton, N; Wang, R; Southworth, A; Whyte, L; Onstott, T C

2017-01-01

The response of methanotrophic bacteria capable of oxidizing atmospheric CH 4 to climate warming is poorly understood, especially for those present in Arctic mineral cryosols. The atmospheric CH 4 oxidation rates were measured in microcosms incubated at 4 °C and 10 °C along a 1-m depth profile and over a range of water saturation conditions for mineral cryosols containing type I and type II methanotrophs from Axel Heiberg Island (AHI), Nunavut, Canada. The cryosols exhibited net consumption of ~2 ppmv CH 4 under all conditions, including during anaerobic incubations. Methane oxidation rates increased with temperature and decreased with increasing water saturation and depth, exhibiting the highest rates at 10 °C and 33% saturation at 5 cm depth (260 ± 60 pmol CH 4 gdw -1 d -1 ). Extrapolation of the CH 4 oxidation rates to the field yields net CH 4 uptake fluxes ranging from 11 to 73 μmol CH 4  m -2 d -1 , which are comparable to field measurements. Stable isotope mass balance indicates ~50% of the oxidized CH 4 is incorporated into the biomass regardless of temperature or saturation. Future atmospheric CH 4 uptake rates at AHI with increasing temperatures will be determined by the interplay of increasing CH 4 oxidation rates vs. water saturation and the depth to the water table during summer thaw. © 2016 John Wiley & Sons Ltd.

AgRISTARS

NASA Technical Reports Server (NTRS)

1984-01-01

An introduction to the overall AgRISTARS program, a general statement on progress, and separate summaries of the activities of each project, with emphasis on the technical highlights are presented. Organizational and management information on AgRISTARS is included in the appendices, as is a complete bibliography of publication and reports.

The structural conversion from α-AgVO3 to β-AgVO3: Ag nanoparticle decorated nanowires with application as cathode materials for Li-ion batteries.

PubMed

McNulty, David; Ramasse, Quentin; O'Dwyer, Colm

2016-09-15

The majority of electrode materials in batteries and related electrochemical energy storage devices are fashioned into slurries via the addition of a conductive additive and a binder. However, aggregation of smaller diameter nanoparticles in current generation electrode compositions can result in non-homogeneous active materials. Inconsistent slurry formulation may lead to inconsistent electrical conductivity throughout the material, local variations in electrochemical response, and the overall cell performance. Here we demonstrate the hydrothermal preparation of Ag nanoparticle (NP) decorated α-AgVO 3 nanowires (NWs) and their conversion to tunnel structured β-AgVO 3 NWs by annealing to form a uniform blend of intercalation materials that are well connected electrically. The synthesis of nanostructures with chemically bound conductive nanoparticles is an elegant means to overcome the intrinsic issues associated with electrode slurry production, as wire-to-wire conductive pathways are formed within the overall electrode active mass of NWs. The conversion from α-AgVO 3 to β-AgVO 3 is explained in detail through a comprehensive structural characterization. Meticulous EELS analysis of β-AgVO 3 NWs offers insight into the true β-AgVO 3 structure and how the annealing process facilitates a higher surface coverage of Ag NPs directly from ionic Ag content within the α-AgVO 3 NWs. Variations in vanadium oxidation state across the surface of the nanowires indicate that the β-AgVO 3 NWs have a core-shell oxidation state structure, and that the vanadium oxidation state under the Ag NP confirms a chemically bound NP from reduction of diffused ionic silver from the α-AgVO 3 NWs core material. Electrochemical comparison of α-AgVO 3 and β-AgVO 3 NWs confirms that β-AgVO 3 offers improved electrochemical performance. An ex situ structural characterization of β-AgVO 3 NWs after the first galvanostatic discharge and charge offers new insight into the Li + reaction

Formation of unexpected silicon- and disiloxane-bridged multiferrocenyl derivatives bearing Si-O-CH[double bond, length as m-dash]CH2 and Si-(CH2)2C(CH3)3 substituents via cleavage of tetrahydrofuran and trapping of its ring fragments.

PubMed

Bruña, Sonia; González-Vadillo, Ana Mª; Ferrández, Marta; Perles, Josefina; Montero-Campillo, M Merced; Mó, Otilia; Cuadrado, Isabel

2017-09-12

The formation of a family of silicon- and siloxane-bridged multiferrocenyl derivatives carrying different functional groups attached to silicon, including Fc 2 (CH 3 ) 3 C(CH 2 ) 2 SiCH[double bond, length as m-dash]CH 2 (5), Fc 2 (CH 2 [double bond, length as m-dash]CH-O)SiCH[double bond, length as m-dash]CH 2 (6), Fc 2 (OH)SiCH[double bond, length as m-dash]CH 2 (7), Fc 2 (CH 2 [double bond, length as m-dash]CH-O)Si-O-Si(O-CH[double bond, length as m-dash]CH 2 )Fc 2 (8) and Fc 2 (CH 2 [double bond, length as m-dash]CH-O)Si-O-SiFc 3 (9) is described. Silyl vinyl ether molecules 6, 8 and 9 and the heteroleptic vinylsilane 5 resulted from the competing metathesis reaction of lithioferrocene (FcLi), CH 2 [double bond, length as m-dash]CH-OLi or (CH 3 ) 3 C(CH 2 ) 2 Li with the corresponding multifunctional chlorosilane, Cl 3 SiCH[double bond, length as m-dash]CH 2 or Cl 3 Si-O-SiCl 3 . The last two organolithium species have been likely formed in situ by fragmentation of the tetrahydrofuran solvent. Diferrocenylvinyloxyvinylsilane 6 is noteworthy since it represents a rare example of a redox-active silyl mononomer in which two different C[double bond, length as m-dash]C polymerisable groups are directly connected to silicon. The molecular structures of the silicon-containing multiferrocenyl species 5, 6, 8 and 9 have been investigated by single-crystal X-ray diffraction studies, demonstrating the capture and storage processes of two ring fragments resulting from the cleavage of cyclic THF in redox-active and stable crystalline organometallic compounds. From electrochemical studies we found that by changing the anion of the supporting electrolyte from [PF 6 ] - to [B(C 6 F 5 ) 4 ] - , the redox behaviour of tetrametallic disiloxane 8 can be switched from a poorly resolved multistep redox process to four consecutive well-separated one-electron oxidations, corresponding to the sequential oxidation of the four ferrocenyl moieties.

Ripening and storage conditions of Chétoui and Arbequina olives: Part II. Effect on olive endogenous enzymes and virgin olive oil secoiridoid profile determined by high resolution mass spectrometry.

PubMed

Hachicha Hbaieb, Rim; Kotti, Faten; Cortes-Francisco, Nuria; Caixach, Josep; Gargouri, Mohamed; Vichi, Stefania

2016-11-01

Several factors affect virgin olive oil (VOO) phenolic profile. The aim of this study was to monitor olive hydrolytic (β-glucosidase) and oxidative (peroxydase, POX, and polyphenoloxydase, PPO) enzymes during olive ripening and storage and to determine their capacity to shape VOO phenolic profile. To this end, olives from the cultivars Chétoui and Arbequina were stored at 4°C or 25°C for 4weeks and their enzymatic activities and oil phenolic profiles were compared to those of ripening olives. We observed different trends in enzymes activities according to cultivar and storage temperature. Secoiridoid compounds, determined by high resolution mass spectrometry (HRMS), and their deacetoxylated, oxygenated, and deacetoxy-oxygenated derivatives were identified and their contents differed between the cultivars according to olive ripening degree and storage conditions. These differences could be due to β-glucosidase, POX and PPO activities changes during olive ripening and storage. Results also show that oxidised phenolic compounds could be a marker of VOO ''freshness". Copyright © 2016 Elsevier Ltd. All rights reserved.

Bimetallic AgCu/Cu2O hybrid for the synergetic adsorption of iodide from solution.

PubMed

Mao, Ping; Liu, Ying; Liu, Xiaodong; Wang, Yuechan; Liang, Jie; Zhou, Qihang; Dai, Yuexuan; Jiao, Yan; Chen, Shouwen; Yang, Yi

2017-08-01

To further improve the capacity of Cu 2 O to absorb I - anions from solution, and to understand the difference between the adsorption mechanisms of Ag/Cu 2 O and Cu/Cu 2 O adsorbents, bimetallic AgCu was doped into Cu 2 O through a facile solvothermal route. Samples were characterized and employed to adsorb I - anions under different experimental conditions. The results show that the Cu content can be tuned by adding different volumes of Ag sols. After doping bimetallic AgCu, the adsorption capacity of the samples can be increased from 0.02 mmol g -1 to 0.52 mmol g -1 . Moreover, the optimal adsorption is reached within only 240 min. Meanwhile, the difference between the adsorption mechanisms of Ag/Cu 2 O and Cu/Cu 2 O adsorbents was verified, and the cooperative adsorption mechanism of the AgCu/Cu 2 O hybrid was proposed and verified. In addition, the AgCu/Cu 2 O hybrid showed excellent selectivity, e.g., its adsorption efficiencies are 85.1%, 81.9%, 85.9% and 85.7% in the presence of the Cl - , CO 3 2- , SO 4 2- and NO 3 - competitive anions, respectively. Furthermore, the AgCu/Cu 2 O hybrid can worked well in other harsh environments (e.g., acidic, alkaline and seawater environments). Therefore, this study is expected to promote the development of Cu 2 O into a highly efficient adsorbent for the removal of iodide from solution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of Pr:LuAG scintillating crystals for X-ray spectroscopy

NASA Astrophysics Data System (ADS)

Bertoni, R.; Bonesini, M.; Cervi, T.; Clemenza, M.; De Bari, A.; Falcone, A.; Mazza, R.; Menegolli, A.; Nastasi, M.; Rossella, M.

2016-07-01

The main features of the Pr doped Lu3Al5O12 (Pr:LuAG) scintillating crystals for X-ray spectroscopy applications have been studied using different radioactive sources and photo-detectors. Pr:LuAG is cheaper, compared to a Germanium detector, but with remarkable properties which make it useful for many applications, from fundamental physics measurements to the PET imaging for medical purposes: high density, elevate light yield, fast response, high energy resolution, no hygroscopicity. A sample of Pr:LuAG crystals with 14 mm×14 mm surface area and 13 mm thickness and a NaI crystal of the same surface and 26 mm thickness used as a reference have been characterized with several radioactive sources, emitting photons in the range 100-1000keV. Different light detectors were adopted for the Pr:LuAG studies, sensitive to its UV emission (peak at 310 nm): a 3 in. PMT (Hamamatsu R11065) and new arrays of Hamamatsu SiPM S13361, with siliconic resin as a window. Preliminary results are presented on the performance of the Pr:LuAG crystals, to be mounted in a 2 × 2 array to be tested in the 2015 run of the FAMU experiment at RIKEN-RAL muon facility. The goal is the detection of the X-rays (around 130 keV) emitted during the de-excitation processes of the muonic hydrogen after the excitation with an IR laser with wavelength set at the resonance of the hyperfine splitting, to measure the muonic atom proton radius with unprecedented precision.

ON THE ORIGIN OF C{sub 4}H AND CH{sub 3}OH IN PROTOSTELLAR ENVELOPES

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

Lindberg, Johan E.; Charnley, Steven B.; Cordiner, Martin A., E-mail: johan.lindberg@nasa.gov

The formation pathways of different types of organic molecules in protostellar envelopes and other regions of star formation are subjects of intense current interest. We present here observations of C{sub 4}H and CH{sub 3}OH, tracing two distinct groups of interstellar organic molecules, toward 16 protostars in the Ophiuchus and Corona Australis molecular clouds. Together with observations in the literature, we present C{sub 4}H and CH{sub 3}OH data from single-dish observations of 40 embedded protostars. We find no correlation between the C{sub 4}H and CH{sub 3}OH column densities in this large sample. Based on this lack of correlation, a difference inmore » line profiles between C{sub 4}H and CH{sub 3}OH, and previous interferometric observations of similar sources, we propose that the emission from these two molecules is spatially separated, with the CH{sub 3}OH tracing gas that has been transiently heated to high (∼70–100 K) temperatures and the C{sub 4}H tracing the cooler large-scale envelope where CH{sub 4} molecules have been liberated from ices. These results provide insight in the differentiation between hot corino and warm carbon-chain chemistry in embedded protostars.« less