Improving Seismic Inversion Robustness via Deformed Jackson Gaussian

The seismic data inversion from observations contaminated by spurious measures (outliers) remains a significant challenge for the industrial and scientific communities. This difficulty is due to slow processing work to mitigate the influence of the outliers. In this work, we introduce a robust formulation to mitigate the influence of spurious measurements in the seismic inversion process. In this regard, we put forth an outlier-resistant seismic inversion methodology for model estimation based on the deformed Jackson Gaussian distribution. To demonstrate the effectiveness of our proposal, we investigated a classic geophysical data-inverse problem in three different scenarios: (i) in the first one, we analyzed the sensitivity of the seismic inversion to incorrect seismic sources; (ii) in the second one, we considered a dataset polluted by Gaussian errors with different noise intensities; and (iii) in the last one we considered a dataset contaminated by many outliers. The results reveal that the deformed Jackson Gaussian outperforms the classical approach, which is based on the standard Gaussian distribution.     

N-oxides of the quinoxaline series

When di-N-oxides of -hydroxymethyl derivatives of quinoxaline are heated with dimethyl sulfoxide, the oxidation of a CH₂OH group and the reduction of a neighboring NO group takes place. The N-oxides of 2,3-bis(hydroxymethyl)qninoxaline undergo similar redox processes in the presence of alkaline reagents.For part XV, see [5].     

Pyrazines and their N-oxides

The N-oxides of 2- and 2,3-substituted pyrazines were synthesized. It was found that the synthesized 2-formylpyrazine N,N-dioxide, in which the aldehyde group is in the hydrated form, undergoes redox transformations leading to deoxidation of one of the ring nitrogens and oxidation of the dihydroxymethyl group to a carboxyl group under the influence of alkaline reagents.See [10] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1275–1280, September, 1972.     

A regression technique to analyze the second-order nonlinear optical response of thin films

We present a new technique, based on regression analysis, to determine the second-order nonlinear optical susceptibility tensor of thin films. The technique does not require the absolute levels or phases of measured signals to be mutually calibrated. In addition it yields indicators that address the quality of theoretical models describing the sample. We use the technique to determine the susceptibility tensor of samples of a nonracemic chiral material which have very low symmetry (both chiral and anisotropic) and have many independent tensor components. The results show the importance of using detailed theoretical models that account for the linear optical properties of the sample.     

ESI-FTICR investigation of triethylammonium ion-driven resorcin[4]arene dimer formation and structure

In the course of mass spectrometric measurements a self-assembled hydrogen bonded resorcinarene dimer was observed, the formation of which was driven by the binding of triethylammonium ion as a guest and as an ionic label.     

Quinoxaline N-oxides

It is found that 2,3-dimethylquinoxaline-l, 4-di-N-oxide reacts with formaldehyde only in the presence of alkaline reagents, and that independent of the amount of formaldehyde taken, 2-(-hydroxyethyl)-3-methyl- and 2, 3-bis ( -hydroxyethyl) quinoxaline-di-N-oxides are formed. Oxidation of quinoxaline derivatives of general formula VI gives the corresponding mono- and di-N-oxides.For Part X see [3].     

N-oxides of imidazo[4,5-b]quinoxalines and imidazo[4,5-b]pyrazines

The N-oxides and N,N-dioxides of methyl derivatives of imidazo[4,5-b]quinoxaline and imidazo[4,5-b]pyrazine were synthesized. The higher reactivity of the 2-methyl group in the N-oxides of 2-methylimidazo[4,5-b]quinoxaline as compared with the corresponding unoxidized derivatives was demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1266–1270, September, 1972.     

Silica-titania sol-gel hybrid materials: synthesis, characterization and potential application in solid phase extraction

The biphenilaminepropylsilica and biphenilaminepropylsilicatitania were synthesized by sol-gel method, in two steps: (a) biphenylamine reacts with chloropropyltrimethoxysilane and (b) the product of reaction was polycondensed with tetraethylorthosilicate (TEOS) or TEOS and titanium isopropoxide. The sol-gel materials were characterized using infrared spectroscopy and N₂ adsorption-desorption isotherms and they were employed as sorbents for carcinogenic N-containing compound retention, in aqueous solution, using the SPE technique. The N-containing compounds adsorption was influenced by the titania presence and the sorption process seems to happen in the pores with higher organic density.     

Spontaneous Resolution of an Electron‐Deficient Tetrahedral Fe4L4 cage

A highly electron‐deficient C₃‐symmetric tris(bipyridyl) ligand was prepared in four steps and used for the coordination of Fe(OTf)₂, thereby resulting in the homochiral assembly of a new family of robust tetrahedral M₄L₄ cages. This homochiral T‐symmetric cage containing a relatively large cavity of 330 ų is capable of encapsulating an anionic guest, as was determined by mass spectrometry, ¹⁹F NMR spectroscopy, and finally shown from its crystal structure. Moreover, crystallization of the cage from CH₃CN led to crystals containing both (ΔΔΔΔ and ΛΛΛΛ) enantiomers, while crystallization from CH₃OH resulted in crystals containing only the right‐handed (ΔΔΔΔ) cage. The difference in the crystal packing of the two crystal structures is discussed and a feasible explanation for the unique phenomenon among supramolecular cages—spontaneous resolution—is given.     

The use of ultrasound in the extraction of Ilex paraguariensis leaves: a comparison with maceration

The objective of this work is to discuss the main parameters that influence the sonication extraction of Ilex paraguariensis leaves. For this purpose, the extraction time, solvent polarity, solvent volume, sample mass and particle size were evaluated. Results showed that the main variable affecting the extraction process was the solvent polarity. Though in a less extent, temperature and extraction time also demonstrated to be important parameters, while the other variables did not present a significant influence on the extraction yield. The extracts at the optimized condition were compared with those obtained by maceration, in terms of mass yield and chemical composition. The major compounds identified in the extracts were caffeine and palmitic acid. Some saturated hydrocarbons such as fatty acids, fatty acid methyl esters, phytosterols, and theobromine were also identified in the fractions.