N2 Lines Research Articles

Optical emission spectra of chromium doped nanocrystalline zinc gallate

Optical emission spectra of nanocrystalline zinc gallate (ZnGa2O4) and trivalent chromium ion doped zinc gallate (ZnGa2O4:Cr3+) are reported for different concentrations of the dopant ion. The measurements have been carried out over the temperature range between 77 and 296 K. The emission spectrum of nanocrystalline ZnGa2O4 shows two broad peaks. The intensity variation in these peaks, with temperature, is indicative of the effect of symmetry breaking in the electronic band structure of ZnGa2O4 in nanocrystalline samples. In addition, we find that the relative intensities of the sharp spectral lines of Cr3+ in nanocrystalline ZnGa2O4:Cr3+ are quite different from those reported for corresponding bulk samples. The spectral profiles of the so-called R1, R2, N1, and N2 lines have also been studied. The data are analyzed using crystal field theory, which includes an exchange interaction between the nearest neighbor Cr3+ pairs in ZnGa2O4. We estimate the exchange parameters for Cr3+ in nanocrystalline ZnGa2O4:Cr3+. Though, in the literature, there exist reports on optical properties of the corresponding bulk spinel, our approach and consequent results on nanocrystalline ZnGa2O4:Cr3+ are not only interesting from the physics point of view but also can be of use in nanotechnology.

EPR, ESE and pulsed ENDOR study of the nitrogen donor pairs on quasi-cubic lattice sites in 6H SiC

Abstract D-band EPR, X-band FS ESE and pulsed ENDOR studies of the additional nitrogen (N) related centers observed in highly compensated n-type 6H-SiC wafers are presented. The D-band EPR and X-band FS ESE spectrum consists of the 14N hyperfine (hf) triplet lines of the N donors incorporated at the two quasi-cubic (Nc1, Nc2) sites with the intensity ratio of INc1/INc2=0.7 and three additional triplet lines. X-band pulsed ENDOR spectra have shown intense 14N ENDOR signals of Nc1, Nc2 centers and new 14N lines due to the N related centers N1, N2, N3 with the isotropic hf splitting: 21.04, 26.43, 29.77 MHz, respectively. It was found that the g-tensors of the N2 and N3 triplet lines coincide with those of N on quasi-cubic Nc2 site. The g-tensor of the third N1 triplet lines corresponds to the average value of the Nc1 and Nc2 spectrum: g ( N 1 ) ≈ 1 2 [ g ( N c 1 ) + g ( N c 2 ) ] . It was suggested that N1 center with Aiso=21.04 MHz is due to the spin coupling between N on two quasi-cubic Nc1 and Nc2 sites while two others are tentatively attributed to the N pairs formed between N atoms on one quasi-cubic Nc2 site.

On a Question of Bourgain about Geometric Incidences

Given a set of s points and a set of n2 lines in three-dimensional Euclidean space such that each line is incident to n points but no n lines are coplanar, we show that s = Ω(n11/4). This is the first non-trivial answer to a question recently posed by Jean Bourgain.

Optical emission spectroscopy characterization of oxygen plasma during degradation of Escherichia coli

Optical emission spectroscopy was applied for plasma characterization during sterilization of substrates contaminated with bacteria. The amount of 1010∕ml cells of Escherichia coli was carefully applied to glass substrates and exposed to oxygen plasma glow discharge at different pressures between 30 and 200Pa. Plasma was created in a glass discharge tube by an inductively coupled rf generator at the frequency of 27.12MHz and output power of about 250W. The electron temperature and plasma density were estimated with a double Langmuir probe. They were between 3 and 5eV and 2 and 35×1015m−3. Density of neutral oxygen atoms was measured with a catalytic probe, and was between 2 and 6×1021m−3. Optical emission spectroscopy was performed with a low resolution spectrometer. The emission from carbon monoxide and nitrogen molecules was used to monitor the evolution of bacteria degradation. Both signals expressed a well defined maximum corresponding to peak erosion of bacteria by plasma radicals. As the sterilization was accomplished, both CO and N2 lines fell below the detection limit of the spectrometer. The bacteria degradation was also monitored by scanning electron microscope (SEM) and culturing. The SEM images corresponded well with the evolution of CO and N2 lines so the optical emission spectroscopy found a reliable tool for monitoring the sterilization process.

The slopes determined by n points in the plane

Let m12, m13, …, mn-1,n be the slopes of the (n2) lines connecting n points in general position in the plane. The ideal In of all algebraic relations among the mij defines a configuration space called the slope variety of the complete graph. We prove that In is reduced and Cohen-Macaulay, give an explicit Gröbner basis for it, and compute its Hilbert series combinatorially. We proceed chiefly by studying the associated Stanley-Reisner simplicial complex, which has an intricate recursive structure. In addition, we are able to answer many questions about the geometry of the slope variety by translating them into purely combinatorial problems concerning the enumeration of trees

Detailed profile analysis of millimetre 502 and 602 GHz N2O–N2(O2) lines at room temperature for collisional linewidth determination

Deviations of experimental millimetre-absorption line shapes from the usual Voigt profile are evidenced for two room-temperature rotational transitions J = 20 ← 19 (502 GHz) and J = 24 ← 23 (602 GHz) of nitrous oxide perturbed by nitrogen and oxygen. These deviations are shown to be due to collisional narrowing processes encompassed by more sophisticated speed-dependent Voigt or Galatry models. The deduced collision-regime line broadening coefficients are compared to their theoretical estimations by a semi-classical formalism. Even with a rough intermolecular potential composed of electrostatic and pair atom–atom interactions, the theoretical linewidths compare favourably with experimental results for both millimetre and infrared absorption.

Familial Parkinson Mutant α-Synuclein Causes Dopamine Neuron Dysfunction in Transgenic Caenorhabditis elegans

Mutations in alpha-synuclein gene cause familial form of Parkinson disease, and deposition of wild-type alpha-synuclein as Lewy bodies occurs as a hallmark lesion of sporadic Parkinson disease and dementia with Lewy bodies, implicating alpha-synuclein in the pathogenesis of Parkinson disease and related neurodegenerative diseases. Dopamine neurons in substantia nigra are the major site of neurodegeneration associated with alpha-synuclein deposition in Parkinson disease. Here we establish transgenic Caenorhabditis elegans (TG worms) that overexpresses wild-type or familial Parkinson mutant human alpha-synuclein in dopamine neurons. The TG worms exhibit accumulation of alpha-synuclein in the cell bodies and neurites of dopamine neurons, and EGFP labeling of dendrites is often diminished in TG worms expressing familial Parkinson disease-linked A30P or A53T mutant alpha-synuclein, without overt loss of neuronal cell bodies. Notably, TG worms expressing A30P or A53T mutant alpha-synuclein show failure in modulation of locomotory rate in response to food, which has been attributed to the function of dopamine neurons. This behavioral abnormality was accompanied by a reduction in neuronal dopamine content and was treatable by administration of dopamine. These phenotypes were not seen upon expression of beta-synuclein. The present TG worms exhibit dopamine neuron-specific dysfunction caused by accumulation of alpha-synuclein, which would be relevant to the genetic and compound screenings aiming at the elucidation of pathological cascade and therapeutic strategies for Parkinson disease.

Eigenvalues of Finite Projective Planes with an Abelian Cartesian Group

Let M be an incidence matrix for a projective plane of order n. The eigenvalues of M are calculated in the Desarguesian case and a standard form for M is obtained under the hypothesis that the plane admits a (P,L)-transitivity G, |G| e n. The study of M is reduced to a principal submatrix A which is an incidence matrix for n2 lines of an associated affine plane. In this case, A is a generalized Hadamard matrix of order n for the Cayley permutation representation R(G). Under these conditions it is shown that G is a 2-group and n e 2r when the eigenvalues of A are real. If G is abelian, the characteristic polynomial |xI − A| is the product of the n polynomials |x − φ (A)|, φ a linear character of G. This formula is used to prove n is a prime power under natural conditions on A and spectrum(A). It is conjectured that |xI − A| ≡ xn2 mod p for each prime divisor p of n and the truth of the conjecture is shown to imply n e |G| is a prime power.

Absolute UV and VUV emission in the 110–400 nm region from 13.56 MHz driven hollow slot microplasmas operating in open air

We present absolute optical emission spectra in the 110–400 nm regions from radio-frequency-driven (13.56 MHz) hollow slot microplasmas operating in open air at atmospheric pressure. The term microplasma in our research refers to inter-electrode separation (100–600 µm) only, as electrode lengths are scalable from 1 to 30 cm. This creates an extended slot plasma and an associated afterglow plume as described herein. Spectra are presented for gas flows through the microelectrodes of argon and helium with small admixtures of hydrogen and nitrogen into open air. The spectra are discussed in terms of species origin and magnitude of the dominant emission lines. Atomic O and N lines dominate the 110–200 nm region, whereas, in the 200–400 nm region, NO, N2, and NH molecular lines are strongest. The role of the state in the open air microplasmas is discussed and the second positive system of molecular nitrogen (N2(C 3Πg–B 3Πg)), is used to measure the rotational (gas) temperature. Finally, we compare the efficiency and magnitude of light emission from the open air microplasmas with values attainable from commercial sealed mercury lamps in the UVB and UVC regions.

Estimating numbers of EMS-induced mutations affecting life history traits in Caenorhabditis elegans in crosses between inbred sublines

Inbred lines of the nematode Caenorhabditis elegans containing independent EMS-induced mutations were crossed to the ancestral wild-type strain (N2). Replicated inbred sublines were generated from the F1 offspring under conditions of minimal selection and, along with the N2 and mutant progenitor lines, were assayed for several fitness correlates including relative fitness (w). A modification of the Castle-Wright estimator and a maximum-likelihood (ML) method were used to estimate the numbers and effects of detectable mutations affecting these characters. The ML method allows for variation in mutational effects by fitting either one or two classes of mutational effect, and uses a Box-Cox power transformation of residual values to account for a skewed distribution of residuals. Both the Castle-Wright and the ML analyses suggest that most of the variation among sublines was due to a few (approximately 1.5-2.5 on average) large-effect mutations. Under ML, a model with two classes of mutational effects, including a class with small effects, fitted better than a single mutation class model, although not significantly better. Nonetheless, given that we expect there to be many mutations induced per line, our results support the hypothesis that mutations vary widely in their effects.

Effect of Irrigation on the Oil Content and Fatty Acid Composition of Some Sunflower Seeds

The effect of irrigation on the seed yield, oil yield, and oil composition of sunflower in populations of Ekiz1 and VNIIMK 8931, a mixture of N2, N3, and N4 lines, and a synthetic variety obtained from these lines has been studied. The major fatty acid was found to be oleic acid, in addition to linoleic, palmitic, and stearic acids. Irrigation increased seed yield, oil yield, and oil content of all samples. In two of them, the synthetic variety and VNIIMK 8931, the increase was found to be statistically significant. In addition, irrigation of the samples did not increase significantly the amount of oleic and linoleic acids. On the contrary, the amount of linoleic acid in the mixture of N2, N3, and N4 lines and oleic acid in VNIIMK 8931 decreased statistically significantly.

On the variations of [OIII] lines intensities in the spectrum of PN IC 4997

The causes of asynchronous variations of the intensities of OIII ions forbidden lines in the spectrum of compact planetary nebula IC 4997 are considered on the basis of the observational data of. It is shown that the rise of the intensity of line 4363 å and decrease of the intensities of N1 and N2 lines may be best explained by increase of mass-loss-rate from nucleous from 5 × 10–8 up to 2 × 10–7 M/yr within a few years (at constant nucleous effective temperature), with appropriate change of ionization structure of nebula. The arguments of existence of variable hot stellar wind are discussed. The theoretical intensities of lines are calculated by the ionization model of planetary nebulae [4], gyven the radiation fields of the nucleous and hot stellar wind with electron temperature Te= 500000 K.

Excitation of ruby fluorescence at multimegabar pressures

We demonstrate the excitation of strong ruby fluorescence at multimegabar pressures by red incident radiation. We have studied the ruby R1 and N2 lines to 251 GPa and measured the R1 line intensity as a function of pump wavelength. This new method of exciting ruby fluorescence enables easy pressure determination at pressures beyond the 250 GPa limit previously predicted by Ruoff.

Is Z-disk degradation responsible for postmortem tenderization?

A number of studies have suggested that Z-disk degradation is a major factor contributing to postmortem tenderization. These conclusions seem to have been based largely on experimental findings showing that the calpain system has a major role in postmortem tenderization, and that when incubated with myofibrils or muscle strips, purified calpain removes Z-disks. Approximately 65 to 80% of all postmortem tenderization occurs during the first 3 or 4 d postmortem, however, and there is little or no ultrastructurally detectable Z-disk degradation during this period. Electron microscope studies described in this paper show that, during the first 3 or 4 d of postmortem storage at 4 degrees C, both costameres and N2 lines are degraded. Costameres link myofibrils to the sarcolemma, and N2 lines have been reported to be areas where titin and nebulin filaments, which form a cytoskeletal network linking thick and thin filaments, respectively, to the Z-disk, coalesce. Filamentous structures linking adjacent myofibrils laterally at the level of each Z-disk are also degraded during the first 3 or 4 d of postmortem storage at 4 degrees C, resulting in gaps between myofibrils in postmortem muscle. Degradation of these structures would have important effects on tenderness. The proteins constituting these structures, nebulin and titin (N2 lines); vinculin, desmin, and dystrophin (three of the six to eight proteins constituting costameres); and desmin (filaments linking adjacent myofibrils) are all excellent substrates for the calpains, and nebulin, titin, vinculin, and desmin are largely degraded within 3 d postmortem in semimembranosus muscle. Electron micrographs of myofibrils used in the myofibril fragmentation index assay show that these myofibrils, which have been assumed to be broken at their Z-disks, in fact have intact Z-disks and are broken in their I-bands.

Middle and upper atmosphere pressure‐temperature profiles and the abundances of CO2 and CO in the upper atmosphere from ATMOS/Spacelab 3 observations

Based on a new approach, profiles of kinetic temperature and atmospheric pressure between 20 and 116 km altitude and CO2 and CO volume mixing ratios between 70 and 116 km have been derived from the ∼0.01‐cm−1 resolution infrared solar occultation spectra recorded by the atmospheric trace molecular spectroscopy (ATMOS) Fourier transform spectrometer during the Spacelab 3 shuttle mission (April 29 to May 6, 1985). The physical model and CO2 profile results have been obtained from simultaneous multiscan least squares fitting of microwindows containing CO2 lines with temperature‐dependent and temperature‐independent intensities and N2 lines with temperature‐independent intensities. The analysis included the retrieval of tangent height separations between spectra in the lower stratosphere, where independent information shows drifts of the sun tracker field of view on the solar disk. The physical model results are compared with climatological profiles, lower thermospheric temperatures computed with the MSISE‐90 model, and other data. The CO2 retrievals indicate a nearly constant volume mixing ratio of 320 ± 35 ppmv (parts per million, 10−6, by volume) in the 70‐to 90‐km altitude region with a rapid decline in the CO2 volume mixing ratio beginning between 90 and 100 km; at 116 km the CO2 volume mixing ratio has declined to about 70 ppmv and is equal to the CO volume mixing ratio, which has been derived from fits to the (1‐0) CO vibration‐rotation band. The absorption by the v2 + v3 ‐ v2 band of CO2 has been analyzed to quantify nonlocal thermodynamic equilibrium (non‐LTE) effects in the upper mesosphere and lower thermosphere. Up to an altitude of 100 km, the results indicate that the vibrational temperature of the v2 state of CO2 is within 5 K of the kinetic temperature. At higher altitudes, non‐LTE effects are observable with the vibrational temperature of the v2 state cooler than the kinetic temperature by 40 K (48°S) and 70 K (30°N) at 112 km. Above 112 km, lines of the v2 + v3 ‐ v2 band are too weak to be observed in the ATMOS spectra.

A RANDOMIZED ALGORITHM FOR SLOPE SELECTION

A set of n distinct points in the plane defines [Formula: see text] lines by joining each pair of distinct points. The median slope of these O(n2) lines was proposed by Theil as a robust estimator for the slope of the line of best fit for the points. We present a randomized algorithm for selecting the k-th smallest slope of such a set of lines which runs in expected O(n log n) time. An efficient implementation of the algorithm and practical experience with the algorithm are discussed.

Fluorescence line narrowing and spectral energy transfer in pair lines of ruby

The fluorescence line narrowing (FLN) of the N1 and N2 lines of pairs of Cr3+ ions in concentrated ruby has been studied. The structure of the narrowed lines has been explained and measurements of the homogeneous width have been improved. By use of the FLN and time-resolved spectroscopy, spectral transfer within the N1 line has been investigated. A two-phonon-assisted process has been found to be responsible for the transfer.

A study of the dynamics of UV laser photolysis of NOCl and NOBr

The photodissociation of NOCl and NOBr using lasers operating at 193 (ArF), 249 (KrF), 308 (XeCl), and 337 nm(N2) has been studied under collisionless conditions by measuring the infrared fluorescence of the NO product. Little difference between the results for NOBr and NOCl was observed and all results indicate a linear dependence of photodissociation yield on laser power. The extent of NO vibrational excitation observed was quite large in photodissociation utilizing the ArF and KrF laser lines, with states up to v≥16 observed with ArF and up to v≥14 with KrF. The XeCl and N2 lines produced much less NO excitation, up to v≥5. Statistical, half-collision, and Franck–Condon models of the photodissociation dynamics were studied, with best agreement with experiment for dissociation at 193 and 249 nm being obtained using a Franck–Condon model. An excited potential function for NOCl in which the NO properties were taken to be close to that of NO(4Π) was found to predict the shape of the dissociated NO vibrational distribution accurately at both 193 and 249 nm. Photolysis at 308 and 337 nm could also be explained by a Franck–Condon model using the NO(A2Π) state to model the NOCl excited state.

Spectroscopy of the O I 989‐ and 7990‐Å multiplets in the dayglow and aurora

The Spectroscopy of the 2p4 ³P‐2p³3s′ ³D° (989 Å) transition of atomic oxygen and the intermediate branch transition 2p³3p ³P‐2p³3s′ ³D° (7990 Å) has been modelled for an optically thick thermosphere using Monte Carlo simulation. The model reproduces rocket observations of 989 Å in the dayglow and aurora if the e + O electron impact excitation cross section is 8.4×10−18 cm² at 25 eV. The individual 989‐Å multiplet strengths agree with dayglow observations which partially resolve the line structure. The 7990‐Å singlet to doublet ratio observed in auroras is also consistent with the model. No evidence is found for selective absorption of individual triplet and doublet lines of the 989‐Å transition through accidental resonances with rotational lines of N2. This is compatible with the latest wavelength data which indicate that the O I and N2 lines are off resonance by two Doppler widths. The 7990/989 intensity ratio in an aurora is sensitive to the abundance of atomic oxygen and the height distribution of the initial excitation rate and, to a lesser extent, to absorption by O2. Ratios of the 7990‐Å multiplets primarily depend on the O abundance with second‐order dependence on O2 absorption and the characteristic energy of the aurora. Accurate ground‐based observations of the 7990‐Å multiplet ratios may yield the atomic oxygen abundance in auroras to within a factor of 2.

Identification of an N2 line protein of striated muscle.

Three unusually large myofibrillar proteins (Mr, > 500,000) are present in major amounts in the striated muscle of various species. the molecular properties and localization of two of these proteins (Mr, approximately 1 X 10(6)), named "titin," have been reported recently [Wang, K., McClure, J. & Tu, A.(1979) Proc. Natl. Acad. Sci. USA 76, 3698-3702]. We have now purified the third protein (Mr, approximately 5-6 X 10(5)), designated "band 3," from rabbit psoas myofibrils. Band 3 is distinct chemically and immunochemically from titin and myosin heavy chain. Immunofluorescent localization studies of band 3 in glycerinated rabbit psoas myofibrils indicated a biphasic distribution. In sarcomeres 1.8-3.7 micrometer long, band 3 is localized predominately on the N2 line in the phase-contrast lucent region of the I band. Quantitative analysis of light micrographs confirmed the unique behavior of N2 lines described in early electron microscopic studies. As the sarcomeres lengthen, the N2 line moves away from both the Z line and the M line, maintaining the same proportional distance. In very short sarcomeres (1.5-1.8 micrometer), band 3 is found mainly in the A band, suggesting that either the N2 line moves into the A band or that band 3 has dissociated from the N2 line which remains near the Z line. We conclude that band 3 is an N2 line component of rabbit skeletal myofibrils.