Search results for "SPECTRA"
showing 10 items of 3542 documents
Substituted methyl 5β-cholan-24-oates II.13C NMR spectral assignment
1994
The 13C NMR spectra were recorded and assigned for nine derivatives of methyl 5β-cholan-24-oates (esters of bile acids) including hydroxy, oxo and/or acetyloxy groups. Assignments were based on the empirical substituent-induced chemical shifts (SCS), spectral comparison with compounds of similar structure, distortionless enhancement by polarization transfer (DEPT) and proton coupled 13C NMR measurements.
Proton-Induced Multiple Changes of the Absorption and Fluorescence Spectra of Amino-Aza-Oligo(Phenylenevinylene)s
2008
Fluorescent dyes with a high sensitivity of their optical spectra towards changes of the environment were prepared via aldol condensation or Horner olefinations. The main chromophore is a quadrupolar N-substituted 1,4-distyrylbenzene which allows protonation and complexation at various positions resulting in a series of different and significant changes of the optical spectra. The sensitivity of the absorption and emission spectra on solvent polarity, acid, and cations is reported.
Three nuclei n.m.r. spectroscopy of dimethoate compounds. A large solvent effect on the31PSC1H vicinal coupling
1977
Proton, phosphorus and carbon magnetic resonance spectra of dimethoate, dimethoxon, des-N-methyldimethoate, ω-hydroxydimethoate, trimethyldithiophosphate and O,O-dimethyldithiophosphate in different solvents have been measured. Most of the n.m.r. parameters were characteristic of the structural environment of the corresponding nucleus and solvent-independent. However, in the amide structures dimethoate, dimethoxon, des-N-methyldimethoate and ω-hydroxydimethoate the 31PSC1H vicinal coupling showed an unusually large solvent effect of a 2.3 to 6.5 Hz decrease when CDCI3 was replaced by acetone-d6 or DMSO-d6.
The Evolution of Disk Winds from a Combined Study of Optical and Infrared Forbidden Lines
2020
We analyze high-resolution (dv=<10km/s) optical and infrared spectra covering the [OI] 6300 angstrom and [NeII] 12.81 micron lines from a sample of 31 disks in different evolutionary stages. Following work at optical wavelengths, we use Gaussian profiles to fit the [NeII] lines and classify them into HVC (LVC) if the line centroid is more (less) blueshifted than 30 km/s with respect to the stellar radial velocity. Unlike for the [OI] where a HVC is often accompanied by a LVC, all 17 sources with a [NeII] detection have either a HVC or a LVC. [NeII] HVCs are preferentially detected toward high accretors (Macc > 10$^{-8}$ Msun/yr) while LVCs are found in sources with low Macc, low [OI] …
A Novel Non-Stationary Channel Model Utilizing Brownian Random Paths
2014
This paper proposes a non-stationary channel model in which real-time dynamics of the mobile station (MS) are taken into account. We utilize Brownian motion (BM) processes to model targeted and non-targeted dynamics of the MS. The proposed trajectory model consists of both drift and random components to capture both targeted and non-targeted motions of the MS. The Brownian trajectory model is then employed to provide a non-stationary channel model, in which the scattering effects of the propagation area are modelled by a non-centred one-ring geometric scattering model. The starting point of the motion is a fixed point in the propagation environment, whereas its terminating point is a random…
Synthesis of chlorinated alkylbibenzyls and 9-chlororetene
1995
Abstract The synthesis of chlorinated alkylbibenzyls and 9-chlororetene is described. These compounds were synthesized for use as model compounds in analytical and toxicological characterization. The structures of the synthesized model compounds found to be very similar to those identified in pulp mill effluent and products. The 1H NMR and mass spectral data for the compounds are also reported.
Local Spectral Theory for R and S Satisfying RnSRn = Rj
2020
In this paper, we analyze local spectral properties of operators R,S and RS which satisfy the operator equations RnSRn=Rj and SnRSn=Sj for same integers j&ge
Existence and gap-bifurcation of multiple solutions to certain nonlinear eigenvalue problems
1993
IN THIS PAPER we study: (i) a class of operator equations in an abstract Hilbert space; and (ii) the L2-theory of certain nonlinear Schrodinger equations which can be viewed as special cases of (i). In order to describe the type of abstract nonlinear eigenvalue problems to be discussed, consider a real Hilbert space H with scalar product (* , *) and norm II.11 and let S be a (not necessarily bounded) positive self-adjoint linear operator in li. We write S in the form
On some dual frames multipliers with at most countable spectra
2021
A dual frames multiplier is an operator consisting of analysis, multiplication and synthesis processes, where the analysis and the synthesis are made by two dual frames in a Hilbert space, respectively. In this paper we investigate the spectra of some dual frames multipliers giving, in particular, conditions to be at most countable. The contribution extends the results available in literature about the spectra of Bessel multipliers with symbol decaying to zero and of multipliers of dual Riesz bases.
Multiplicity theorems for the Dirichlet problem involving the p-Laplacian
2003
Multiplicity theorems for the Dirichlet problem involving the p-Laplacian were proved using variational approach. It was shown that there existed an open interval and a positive real number, and each problem admits at least three weak solutions. Results on the existence of at least three weak solutions for the Dirichlet problems were established.