N2 Lines Research Articles

Delayed tunneling of charges to deep traps in a ZnO impurity containing Cr3+ doped Zn2TiO4 inverse spinel.

Herein, the structural, optical and thermoluminescence properties of Cr doped Zn2TiO4 are explored extensively for a possible application in bioimaging. All the samples show prominent luminescence at wavelengths 712 and 716 nm, which correspond to Cr R and N2-lines, respectively. These R and N2 lines correspond to the presence of Cr3+ in undistorted and distorted sites. The excitation spectra of all the samples possess at least five different bands at 616, 440, 388, 330 and 283 nm. The persistent luminescence is observed upon excitation at all these wavelengths, suggesting the existence of both localized and delocalized mechanisms. The charges can be easily stored in deeper traps (trap depth > 1.0 eV) upon localized excitation with green and red light sources. However, upon excitation at wavelengths 254 and 365 nm, these traps were found empty when thermoluminescence glow curves were recorded immediately after excitation. Furthermore, it was observed that the trapping in these deeper traps through the delocalized band is possible when a delay in the thermoluminescence measurement is pursued. We attribute the possible reason for such delayed tunneling to the higher probability of retrapping than the recombination process.

Emission spectrum analysis of an atmospheric electrode microwave discharge in argon flow and of a cold plasma jet on its base

The measurements and analysis of the emission spectra both of atmospheric-pressure electrode microwave discharge in argon flow and cold plasma jet induced by the discharge are conducted. We used experimental setup based on the previously developed multipurpose 2.45-Hz-plasmatron with the external portable discharge chamber (plasma torch) with the outlet of 2.5 cm in diameter and power of about several hundred watts. Discharge chamber has 6 rod-like electrodes which form a regular hexagon in a cross section of the torch. Discharge channels are formed between the ends of the electrodes and the inner wall of the chamber. Molecular bands of NO, OH, N2, NH and atomic lines of Ar were found in the spectrum of the discharge channels. Based on the analysis of the spectra, it was shown that the gas temperature in the discharge channel was about 1200 K. In the cold plasma jet spectrum, due to its weak luminescence, only the molecular lines OH and N2 were reliably observed.

A simulation comparison of calibration functions for different sets of spectral filter passbands in the traditional pure rotational Raman lidar technique

The accuracy of tropospheric temperature measurements with pure rotational Raman (PRR) lidars is affected by the collisional broadening of N2 and O2 PRR lines. In this paper, we intercompare nine calibration functions (CFs) in the traditional PRR lidar technique via simulation. Taking into account the PRR line broadening, the simulation is performed for five sets of spectral filters (SFs) with different passbands in a PRR lidar receiving system. For simplicity of calculations, the transmission function of each SF is approximated by a rectangular function on the wavenumber interval, within which a SF passes the bulk of the backscattered signal intensity in the corresponding PRR lidar channel. A narrow-linewidth laser operating at wavelengths of 354.67 and 532 nm is considered as a lidar transmitter. The CF best suited for tropospheric temperature retrievals from raw PRR lidar data for each set of SFs and laser wavelength is determined by comparative analysis of calibration errors ΔT produced using these CFs. The absolute error |ΔT| does not exceed the value of 3 × 10–3 K when using the best three-coefficient CF, while |ΔT| < 4 × 10–4 K for the best four-coefficient CF regardless of the laser wavelength and SF set used.

The Ancestral Caenorhabditis elegans Cuticle Suppresses rol-1.

Genetic background commonly modifies the effects of mutations. We discovered that worms mutant for the canonical rol-1 gene, identified by Brenner in 1974, do not roll in the genetic background of the wild strain CB4856. Using linkage mapping, association analysis and gene editing, we determined that N2 carries an insertion in the collagen gene col-182 that acts as a recessive enhancer of rol-1 rolling. From population and comparative genomics, we infer the insertion is derived in N2 and related laboratory lines, likely arising during the domestication of Caenorhabditis elegans, and breaking a conserved protein. The ancestral version of col-182 also modifies the phenotypes of four other classical cuticle mutant alleles, and the effects of natural genetic variation on worm shape and locomotion. These results underscore the importance of genetic background and the serendipity of Brenner’s choice of strain.

Extending Erdős–Beck's theorem to higher dimensions

Erdős-Beck's theorem states that n points in the plane with at most n−x points collinear define at least cxn lines for some positive constant c. It implies n points in the plane define Θ(n2) lines unless most of the points (i.e. n−o(n) points) are collinear.In this paper, we will present two ways to extend this result to higher dimensions. Given a set S of n points in Rd, we want to estimate a lower bound of the number of hyperplanes they define (a hyperplane is defined or spanned by S if it contains d+1 points of S in general position). Our first result says the number of spanned hyperplanes is at least cxnd−1 if there exists some hyperplane that contains n−x points of S and is saturated (as defined in Definition 1.3). Our second result says n points in Rd define Θ(nd) hyperplanes unless most of the points belong to the union of a collection of flats whose dimension sum to less than d.Our result has an application to point-hyperplane incidences and a potential application to the point covering problem.

Triboluminescence of tris(2,2′-bipyridyl)ruthenium(II) dichloride hexahydrate

The triboluminescence of tris(2,2′-bipyridyl)ruthenium(II) dichloride hexahydrate complex is detected during the mechanical grinding. The intense lines of N2 in the UV region and a band at 619 nm appeared due to luminescence of [Ru(bpy)3]2+ ion and coincided with the photoluminescence spectrum of the crystals are observed in the emission spectrum in air. The luminescence of N2 is due to electrification of the crystals during the destruction and subsequent discharges in the gas phase. We showed that the luminescence of [Ru(bpy)3]2+ does not occur due to absorption of UV luminescence of N2, because there is only luminescence of the crystal in O2 environment, whereas the luminescence of N2 is completely suppressed. The intense lines coincided with those of Ne and Ar atoms in the electric discharge are observed in the triboluminescence spectra of ruthenium(II) complex in neon and argon environments. In this case, there is an increase in intensity of N2 lines and of a band of [Ru (bpy)3]2+ due to more intense discharges than during the tribodestruction without inert gases. *OH radical is also detected in the triboluminescence spectrum due to mechanochemical decomposition of water molecules in the [Ru(bpy)3]Cl2·6H2O crystalline hydrate.

The spectrum of N2 from 4,500 to 15,700 cm−1 revisited with pgopher

Using a reference molecular atlas to ensure self-consistency of wavelength calibration is widespread practice. Boesch & Reiners (Astronomy & Astrophysics 582 A43 (2015)) reported a line list from a discharge of molecular nitrogen from 4500 to 11,000 cm−1 for this purpose. With a hollow-cathode discharge source, we have extended the experimental spectrum up to 15,700 cm−1, to include the range of Ti:sapphire lasers, since the density of N2 lines is greater than atomic atlases in common use. Recognizing that experimental conditions can vary, we have also analysed the spectra (comprising several B3Πg−A3Σu+, B′3Σu−−B3Πg, and W3Δu −B3ΠgN2 bands) with standard Hamiltonians, so that any part of the discharge spectrum in the range 4,500–15,700 cm−1 can be simulated. Parameters are given to do this with the spectral simulation and analysis package pgopher. (C. Western, J. Quant. Spectrosc. Rad. Transf., 186, 221 (2016)). The analysis also included high-level ab initio calculations of potential energy curves, transition moments and spin-orbit coupling constants and these were used in preparing the model, extending the potential range of applicability. The results are available in a variety of formats to suit possible applications, including the experimental spectrum in ASCII, a detailed line list with positions and Einstein A coefficients, and a PGOPHER input file to synthesize the spectrum at selectable temperature and resolution.

Comparative analysis of calibration functions in the pure rotational Raman lidar technique

Calibration functions (CFs) are required for the pure rotational Raman (PRR) technique to retrieve atmospheric temperature profiles from raw lidar data. The accuracy of temperature retrievals essentially depends on the selected CF, especially in the troposphere where the molecular collision effect dominates over the Doppler one. In this paper, we theoretically and experimentally compare nine different CFs (five of which are suggested for the first time) to determine the best function for the tropospheric temperature retrievals. All the CFs represent special cases of the general CF that takes into account the collisional broadening of individual atmospheric N2 and O2 PRR lines. The comparative analysis of calibration errors ΔTerr produced using these CFs in a simulation study showed that the best CF among them gives |ΔTerr| < 4 × 10− 5 K. To determine the best CF from a practical standpoint, we apply all the functions to nighttime measurement data obtained in Tomsk (56.48°N, 85.05°E, Western Siberia, Russia) with a PRR lidar designed in the Institute of Monitoring of Climatic and Ecological Systems (IMCES). The CF best-suited for the tropospheric temperature measurements with the IMCES PRR lidar is the same as determined by simulation.

Validity of abundances derived from spaxel spectra of the MaNGA survey

We measured the emission lines in the spaxel spectra of Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) galaxies in order to determine the abundance distributions therein. It has been suggested that the strength of the low-ionization lines, R2, N2, and S2, may be increased (relative to Balmer lines) in (some) spaxel spectra of the MaNGA survey due to a contribution of the radiation of the diffuse ionized gas. Consequently, the abundances derived from the spaxel spectra through strong-line methods may suffer from large errors. We examined this expectation by comparing the behaviour of the line intensities and the abundances estimated through different calibrations for slit spectra of H II regions in nearby galaxies, for fibre spectra from the Sloan Digital Sky Survey, and for spaxel spectra of the MaNGA survey. We found that the S2 strength is increased significantly in the fibre and spaxel spectra. The mean enhancement changes with metallicity and can be as large as a factor of ~2. The mean distortion of R2 and N2 is less than a factor of ~1.3. This suggests that Kaufmann et al.’s (2003, MNRAS, 346, 1055) demarcation line between active galactic nuclei and H II regions in the Baldwin, Phillips, &amp; Terlevich (BPT, 1981, PASP, 93, 5) diagram is a useful criterion to reject spectra with significantly distorted strengths of the N2 and R2 lines. We find that the three-dimensional R calibration, which uses the N2 and R2 lines, produces reliable abundances in the MaNGA galaxies. The one-dimensional N2 calibration produces either reliable or wrong abundances depending on whether excitation and N/O abundance ratio in the target region (spaxel) are close to or differ from those parameters in the calibrating points located close to the calibration relation. We then determined abundance distributions within the optical radii in the discs of 47 MaNGA galaxies. The optical radii of the galaxies were estimated from the surface brightness profiles constructed based on the MaNGA observations.

Cr3+ Doped Al2O3 Obtained by Non-Hydrolytic Sol-Gel Methodology

This paper reports the synthesis and characterization of Cr3+-doped alumina by the sol-gel non-hydrolytic methodology. The resulting sample was treated at different temperatures. X-ray diffraction revealed that the ruby phase emerged in the sample treated at 1100 oC, which was later confirmed by absorption bands correspondent to Cr3+ ions allowed transitions at 4A2 → 4T1, 4T2, and forbidden at 4A2 → 2T1, 2E, observed by diffuse reflectance UV-Vis. The luminescence spectroscopy showed the intensity band at 694 nm in red region, characterized of the Cr3+ ion. The peaks at 702 and 705 nm correspond to N1 and N2 lines, respectively, which arose from the second and fourth nearest-neighbor exchange-coupled pairs of chromium(III) ion, respectively, ascribed to high chromium(III) concentration. The Cr3+ cluster formation was observed in electron paramagnetic resonance signal as discussed in this work. Nuclear magnetic resonance evidenced that the 27 Al symmetry changed in the samples treated between 900 and 1100 oC.

Tropospheric temperature measurements with the pure rotational Raman lidar technique using nonlinear calibration functions

Abstract. Among lidar techniques, the pure rotational Raman (PRR) technique is the best suited for tropospheric and lower stratospheric temperature measurements. Calibration functions are required for the PRR technique to retrieve temperature profiles from lidar remote sensing data. Both temperature retrieval accuracy and number of calibration coefficients depend on the selected function. The commonly used calibration function (linear in reciprocal temperature 1∕T with two calibration coefficients) ignores all types of broadening of individual PRR lines of atmospheric N2 and O2 molecules. However, the collisional (pressure) broadening dominates over other types of broadening of PRR lines in the troposphere and can differently affect the accuracy of tropospheric temperature measurements depending on the PRR lidar system. We recently derived the calibration function in the general analytical form that takes into account the collisional broadening of all N2 and O2 PRR lines (Gerasimov and Zuev, 2016). This general calibration function represents an infinite series and, therefore, cannot be directly used in the temperature retrieval algorithm. For this reason, its four simplest special cases (calibration functions nonlinear in 1∕T with three calibration coefficients), two of which have not been suggested before, were considered and analyzed. All the special cases take the collisional PRR lines broadening into account in varying degrees and the best function among them was determined via simulation. In this paper, we use the special cases to retrieve tropospheric temperature from real PRR lidar data. The calibration function best suited for tropospheric temperature retrievals is determined from the comparative analysis of temperature uncertainties yielded by using these functions. The absolute and relative statistical uncertainties of temperature retrieval are given in an analytical form assuming Poisson statistics of photon counting. The vertical tropospheric temperature profiles, retrieved from nighttime lidar measurements in Tomsk (56.48° N, 85.05° E; Western Siberia, Russia) on 2 October 2014 and 1 April 2015, are presented as an example of the calibration functions application. The measurements were performed using a PRR lidar designed in the Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences for tropospheric temperature measurements.

Spectroscopic analysis of coal plasma emission produced by laser ablation

An analysis of plasma produced by laser ablation using 1,064 nm of laser radiation from a Q-switched Nd:YAG on coal mineral samples under air ambient, was performed. The emission of molecular band systems such as C2 Swan System , the First Negative System N2 (Band head at 501.53 nm) and different emission lines were investigated using the optical emission spectroscopy technique. The C2 molecular spectra (Swan band) were analyzed to determine vibrational temperature (0.62 eV). The density and electron temperature of the plasma have been evaluated using Stark broadening and the intensity of the nitrogen emission lines (N II). Values of 1.2 eV of electron temperature and 1.82×1019 cm-3 of electron density were found.

Spectroscopic study of emission coal mineral plasma produced by laser ablation

Spectroscopic analysis of plasma produced by laser ablation of coal samples using 1064 nm radiation pulses from a Q-switched Nd:YAG on different target under air ambient, was performed. The emission of molecular band systems such as C2 Swan System (d3Πg→a3Πu), the First Negative System N2 (Band head at 501,53 nm) and emission lines of the C I, C II, were investigated using the optical emission spectroscopy technique. The C2 molecular spectra (Swan band) were analyzed to determine vibrational temperature (0,62 eV); the density and electron temperature of the plasma have been evaluated using Stark broadening and the intensity of the nitrogen emission lines N II, the found values of 1,2 eV and 2,2 x1018 cm−3 respectively.

Synthesis of zinc oxide nanoparticles by dc arc dusty plasma

Optical emission signals of a dc arc plasma system that was used for generating ZnO nanoparticles (NPs) have been investigated in gas phase as a function of chamber pressure and arc current. In this technique, a commercially available zinc 4N rod is used as a zinc source, as well as anode in the dc circuit and ambient air as an oxygen source. A carbon rod acts as the cathode. The optical transitions of Zn(I) and O(I) in addition, excitation of high energy states of N2, CN, and atomic nitrogen lines were observed in OES due to increase of electron temperature than gas temperature (T e > T g) by reducing the chamber pressure from 760 torr to lower pressures. The as-prepared NPs show good crystalline quality with hexagonal wurtzite structure and the particle size was ranging from few nm to 100 nm in the form of rod and spherical morphologies. The impurity nature and structural properties of as-prepared NPs by dc arc plasma experiments were correlated with OES and Raman spectroscopy.

Relationship between intensities of strong emission lines in the spectra of H II regions and their chemical compositions

The method of determination of heavy element abundances in H II regions (the strong-line method) uses the assumption that some combinations of strong emission line intensities in spectra of H II regions can serve as indicators of metallicities and electron temperatures in nebulosities. Three sets of strong lines are considered, namely, A (R3, R2, N2, S2 lines), B (R3, R2, N2 lines), and C (R3, N2, S2 lines). Strong line intensities are normalized to the Hβ intensity). We searched for an unambiguous relationship between strong emission line intensities of these line sets in spectra of H II regions and their compositions. The extensive model grid for H II regions is computed. Chemical compositions of nebulosities and intensities of A and C lines are shown to be related unambiguously. For the B line set, 5% of model H II regions do not have any unambiguous relationship, namely, the models with appreciably different oxygen and nitrogen abundances in H II regions can have similar intensities of the B set lines. The versions of strong-line method (calibrations) using the A and C lines are more reliable than those based on the B lines.

Targeted Identification of Metastasis-associated Cell-surface Sialoglycoproteins in Prostate Cancer

Covalent attachment of carbohydrates to proteins is one of the most common post-translational modifications. At the cell surface, sugar moieties of glycoproteins contribute to molecular recognition events involved in cancer metastasis. We have combined glycan metabolic labeling with mass spectrometry analysis to identify and characterize metastasis-associated cell surface sialoglycoproteins. Our model system used syngeneic prostate cancer cell lines derived from PC3 (N2, nonmetastatic, and ML2, highly metastatic). The metabolic incorporation of AC4ManNAz and subsequent specific labeling of cell surface sialylation was confirmed by flow cytometry and confocal microscopy. Affinity isolation of the modified sialic-acid containing cell surface proteins via click chemistry was followed by SDS-PAGE separation and liquid chromatography-tandem MS analysis. We identified 324 proteins from N2 and 372 proteins of ML2. Using conservative annotation, 64 proteins (26%) from N2 and 72 proteins (29%) from ML2 were classified as extracellular or membrane-associated glycoproteins. A selective enrichment of sialoglycoproteins was confirmed. When compared with global proteomic analysis of the same cells, the proportion of identified glycoprotein and cell-surface proteins were on average threefold higher using the selective capture approach. Functional clustering of differentially expressed proteins by Ingenuity Pathway Analysis revealed that the vast majority of glycoproteins overexpressed in the metastatic ML2 subline were involved in cell motility, migration, and invasion. Our approach effectively targeted surface sialoglycoproteins and efficiently identified proteins that underlie the metastatic potential of the ML2 cells.

Whole Genome Sequencing Highlights Genetic Changes Associated with Laboratory Domestication of C. elegans

Defining the mutational landscape when individuals of a species grow separately and diverge over many generations can provide insights into trait evolution. A specific example of this involves studying changes associated with domestication where different lines of the same wild stock have been cultivated independently in different standard environments. Whole genome sequence comparison of such lines permits estimation of mutation rates, inference of genes' ancestral states and ancestry of existing strains, and correction of sequencing errors in genome databases. Here we study domestication of the C. elegans Bristol strain as a model, and report the genome sequence of LSJ1 (Bristol), a sibling of the standard C. elegans reference wild type N2 (Bristol). The LSJ1 and N2 lines were cultivated separately from shortly after the Bristol strain was isolated until methods to freeze C. elegans were developed. We find that during this time the two strains have accumulated 1208 genetic differences. We describe phenotypic variation between N2 and LSJ1 in the rate at which embryos develop, the rate of production of eggs, the maturity of eggs at laying, and feeding behavior, all the result of post-isolation changes. We infer the ancestral alleles in the original Bristol isolate and highlight 2038 likely sequencing errors in the original N2 reference genome sequence. Many of these changes modify genome annotation. Our study provides a starting point to further investigate genotype-phenotype association and offers insights into the process of selection as a result of laboratory domestication.

Abstract 3307: Cell-surface glycoproteomics identifies CUB-domain containing protein 1 to be associated with prostate cancer metastasis

Abstract Prostate cancer is still the most common and second leading cause of cancer death in men in the United States and is overwhelmingly lethal when metastatic. Evidence from histochemical analysis and experimental tumor models indicates alterations in cell-surface sialylation as a general observation associated with the metastatic potential of tumor cells. Our preliminary data from lectin staining also demonstrates changes of cell-surface sialylation in a syngeneic prostate cancer cell model, which includes two PC3 sublines, N2 (non-metastatic) and ML2 (highly metastatic). Characterization of cell-surface sialylated glycoproteins in this model system could provide new information related to the metastatic phenotype in prostate cancer. Thus, cell-surface sialoglycoproteins in the N2 and ML2 cell lines were metabolicly labeled with with an unnatural mannose analogue (AC4ManNAz); This was followed by chemoselective conjugation of the azido sugars with a biotinylated alkyne capture reagent via Cu (I) catalyzed click chemistry and affinity detection and enrichment by streptavidin-conjugated beads (or fluorescein). Captured glycoproteins were separated by 1D gel electrophoresis, in-gel proteolytic digestion, and protein identification by means of tandem mass spectrometry (LC-MS/MS). The expression of the targeted sialoglycoproteins was verified in our prostate cancer cell lines and clinical samples by means of Western blot, confocal microscopy and fluorescent immunohistochemistry. Forty three cell-surface N-linked glycoproteins were identified as differentially expressed between the PC3 metastasis variants, including CUB-domain containing protein 1 (CDCP1). Western blot analysis of the cell-surface glycoprotein enriched fractions and total cell lysate confirmed that CDCP1 was over-expressed in the metastatic ML2 cells. Expression of CDCP1 is dysregulated in prostate cancer tissues, with malignant glands showing a more intense cell surface staining pattern, whereas normal glands demonstrated weak membrane and intracellular granular staining on the basal side. We conclude that glycan metabolic labeling technology combined with mass spectrometry analysis provides a powerful tool for the identification of specific cell-surface glycoproteins that may contribute to prostate cancer metastasis, like CDCP1. Further studies are warranted to evaluate the clinical value of CDCP1 and to understand its function in prostate cancer progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3307.

Study on the Effect of Base Pressure on Magnetron Sputtering Discharge Plasma by Optical Emission Spectroscopy

Argon plasma was generated by DC magnetron sputtering discharge at a constant input power and sputtering pressure. The emission spectra of the argon plasma, in a region of 300 nm to 800 nm, were recorded with three different base pressures (4×10−4 Pa, 13×10−4 Pa and 26×10−4 Pa). From the spectra, the Boltzmann temperature (TB) was calculated by using the atomic Boltzmann plot method. The intensity ratio of N and N2 lines provided the information on the changes in the degree of dissociation of nitrogen molecules. The obtained results showed that with the increase in base pressure the dissociation of N2 increased and the Boltzmann temperature (TB) decreased.

Calculations of ozone line shifting induced by N2 and O2 pressure

Ozone line shifts by nitrogen and oxygen pressure are computed for the ν1 + ν3, 2ν1 and 2ν3 bands of the 5 μm spectral region by a semiempirical approach. The calculated values agree with measurements better than 0.001 cm−1 atm−1 for 98% of O3–N2 lines and 87% of O3–O2 lines. In contrast with the water molecule case, the polarization components of the interaction potential are shown to contribute to the line shift more efficiently than the electrostatic interactions. As intermediate results, the mean dipole polarizability and the components of the polarizability tensor for the vibrational states (101), (200), and (002) of ozone molecule are determined by least-squares fitting of theoretical shifts to some experimental values. The temperature exponents for the ν1 + ν3 band lines are also estimated.