Rearrangement Procedure Research Articles

Second-Order Horizontal Multi-Synchrosqueezing Transform for Hydrocarbon Reservoir Identification

Time-frequency (TF) analysis has received considerable attention in seismic spectral anomaly detection for its superiority in significantly revealing the frequency content of seismic signals changing with time variation. In this letter, a novel method termed second-order horizontal multi-synchrosqueezing transform (SHMSST) is proposed for hydrocarbon reservoir identification. First, a Gaussian-modulated linear chirp model is constructed in the frequency domain for describing the signals with slowly or rapidly linear-varying group delay. Then, the second-order local group delay estimation of the model is deduced in the TF domain through an approach similar to the instantaneous frequency estimation in the synchrosqueezing transform (SST). Finally, the rearrangement procedure is executed iteratively to concentrate the blurry TF energy into the estimated group delay, which provides an energy-concentrated TF representation for the signals with distinct nonlinear and nonstationary features. Synthetic signal and field seismic data illustrate the effectiveness of the proposed SHMSST in time localization and direct hydrocarbon detection.

Parameter Sensitivity Analysis and Structural Development of an Airliner Lavatory Unit by Means of Finite Element Method

The current lavatory blocks – which can be found on the board of different airliners – are connected to the aeroplane structure not just through their lower attachments but through their upper ones as well. This upper attachment makes their installation and rearrangement procedures difficult and time-consuming. Therefore, investigations are being carried out to ignore the mentioned attachment together with keeping the requirements. Structural stress analyses have been completed in the present work for the lavatory block without upper attachment using some solutions for increasing the structural integrity, in order to learn the effects of various static loads. The results of the different scenarios are investigated and compared to the outcomes of the lavatory block without upper attachment. In order to get a solution that meets the related safety requirements, parameter-sensitivity analyses of the lavatory structure have been completed. Based on the results of the survey and keeping the targets, the cost-effectiveness, feasibility and possible future tests in mind, a configuration that meets the authority requirements is determined. The advantages and disadvantages of the modifications are discussed, and suggestions are made at the end for the further steps to proceed.

Synthesis of 10H‐Indolo[1,2‐a]indole Derivatives via Intramolecular Cycloaddition and H‐Migration

AbstractA novel method for synthesizing 10H‐indolo[1,2‐a]indole derivatives is reported here. All products are prepared by applying the intramolecular cyclization strategy at room temperature. The reaction was realized through I2/ZnI2 catalyzed intramolecular nucleophilic addition, hydrogen migration, and rearrangement procedures. The electronic effect and steric hindrance have a significant influence on the reactivity. Moreover, the synthetic value of 10H‐indolo[1,2‐a]indole was also exemplified by the selective decarboxylation and aromatization.

Half a century with Achmatowicz rearrangement

A retrospective account of a synthetic method development, which started as a study of a stepwise oxidative conversion of 2-furyl carbinols to pyranoses (Achmatowicz rearrangement) is presented. Application of most conceivable ways of stereo-differentiation of rearrangement substrates and products over the last 50 years rendered this simple transformation a unique position. Today it is one of the most versatile synthetic tools in synthesis of oxygen and nitrogen heterocyclic compounds, including a great variety of natural products. Evolution of rearrangement procedures which are environmentally friendly and secure firm control over stereochemistry of even most complex target molecules is highlighted. • The Achmatowicz rearrangement was a crucial step in a total synthesis of monosaccharides. • It transforms furyl carbinol into six-membered ring systems containing O or N atom. • There are dozens of conditions and reactants used to perform the rearrangement. • It is an exceptionally useful tool in total syntheses of pharmaceuticals, alkaloids, toxins, etc.

Mechanistic study of fenoprofen photoisomerization to pure (S)-fenoprofen: a DFT study

This work provides a comprehensive DFT study on the conversion mechanism and photoisomerization of the effective and commonly used nonsteroidal anti-inflammatory medicine fenoprofen. The results obtained exhibit that the rearrangement procedure of (R)-fenoprofen to its (S)-enantiomer occurs in [1,3]-hydrogen shifts with inversion of configuration at chiral center C8. According to the computed energies, we can find out that the excitation of (R)-fenoprofen methyl ester in its primary form to the first excited singlet state S1 at λ = 240 nm is the rate-limiting step of photoisomerization of fenoprofen. In order to obtain further insight into the isomerization process occurring upon excitation, this process was studied by scanning the C8-H11 distance for the excited singlet. Our calculations revealed that the isomerization process requires passing a barrier of approximately 84 kcal/mol. Furthermore, the more photostability of (S)-fenoprofen methyl ester than that of its related (R)-enantiomer can be attributed to the − 1.34 kcal/mol of thermodynamic stability of the (S)-fenoprofen methyl ester.

Formation of Complex Hydrazine Derivatives via Aza-Lossen Rearrangement.

The development of a broadly applicable procedure for the aza-Lossen rearrangement is reported. This process converts amines into complex hydrazine derivatives in two steps under safe, mild conditions. This method allows the chemoselective formation of N-N bonds, resulting in the synthesis of cyclic and acyclic products while avoiding side reactions of the amphoteric (ambident) nitrogen-substituted isocyanate intermediate.

Thermolytic Synthesis of Naphthalenes via Intramolecular Cyclocondensation of o-Phenylallylbenzaldehydes

The development of intramolecular carbonyl-ene type cyclocondensation of oxygenated o-phenylallylbenzaldehydes in refluxing decalin is reported. The facile and easy-to-operate thermolytic rearrangement procedure generates substituted naphthalenes in good to excellent yields.

Multi-view stereo in the operating room allows prediction of healing complications in a patient-specific model of reconstructive surgery

Excessive mechanical stress leads to wound healing complications following reconstructive surgery. However, this knowledge is not easily applicable in clinical scenarios due to the difficulty in measuring stress contours during complex tissue rearrangement procedures. Computational tools have been proposed as an alternative to address this need, but obtaining patient specific geometries with an affordable and flexible setup has remained a challenge. Here we present a methodology to determine the stress contours from a reconstructive procedure on a patient-specific finite element model based on multi-view stereo (MVS). MVS is a noninvasive technology that allows reconstruction of 3D geometries using a standard digital camera, making it ideal for the operating room. Finite element analysis can then be used on the patient-specific geometry to perform a virtual surgery and predict regions at risk of complications. We applied our approach to the case of a 7-year-old patient who was treated to correct a cranial contour deformity and resect two large areas of scalp scarring. The simulation showed several zones of high stress, particularly near the suture lines at the distal ends of the flaps. The patient did show delayed healing and partial flap tip necrosis at one of such predicted regions at the 30-day follow up visit. Our results further establish the application of computational tools in individualized medical scenarios to advance preoperative planing and anticipate regions of concern immediately after surgery.

Multiple ionization of Au by fast Sq+ ions of energy 0.4–3.8 MeV/amu

The measurements of the M- and N-shell ionization probabilities in gold bombarded by highly charged Sq+ (q=4–14) ions of energy 0.4–3.8MeV/amu are reported. The ionization probabilities were extracted from the measured L-X-ray spectra which were substantially modified by the multiple ionization effects. The observed L-X-ray line shifts and broadening allowed us (Banaś et al., 2002) to extract both the M- and N-shell ionization probabilities for the zero impact parameter. These ionization probabilities, which correspond to the moment of X-ray emission, were correlated with the ionization probabilities for the moment of ion impact ionization by using the vacancy rearrangement procedure developed here. In this way the ionization probabilities for the moment of ion impact multiple ionization were obtained. By comparing to the theoretical predictions of the semiclassical approximation (SCA) (Trautmann and Kauer, 1989) and the “geometrical model” (GM) (Sulik et al., 1987) based on the binary encounter approximation (BEA), the role of the electronic wave functions and the binding effect is discussed. Generally, the calculations using the hydrogenic wave functions reproduce the measured ionization probabilities.

Asymmetric Synthesis of Substituted anti-β-Fluorophenylalanines.

A range of substituted anti-β-fluorophenylalanines was produced from the corresponding enantiopure α-hydroxy-β-amino esters using a stereospecific XtalFluor-E promoted rearrangement procedure as the key step. The requisite substrates are readily produced via aminohydroxylation of an α,β-unsaturated ester using our lithium amide conjugate addition methodology and, following rearrangement, deprotection of the resultant enantiopure β-fluoro-α-amino esters gives the corresponding enantiopure anti-β-fluorophenylalanines in good yield and high diastereoisomeric purity.

NLS ground states on graphs

We investigate the existence of ground states for the subcritical NLS energy on metric graphs. In particular, we find out a topological assumption that guarantees the nonexistence of ground states, and give an example in which the assumption is not fulfilled and ground states actually exist. In order to obtain the result, we introduce a new rearrangement technique, adapted to the graph where it applies. Owing to such a technique, the energy level of the rearranged function is improved by conveniently mixing the symmetric and monotone rearrangement procedures.

Cornish-Fisher Expansion for Commercial Real Estate Value at Risk

The computation of Value at Risk has traditionally been a troublesome issue in commercial real estate. Difficulties mainly arise from the lack of appropriate data, the non-normality of returns, and the inapplicability of many of the traditional methodologies. As a result, calculation of this risk measure has rarely been done in the real estate field. However, following a spate of new regulations such as Basel II, Basel III, NAIC and Solvency II, financial institutions have increasingly been required to estimate and control their exposure to market risk. As a result, financial institutions now commonly use “internal” Value at Risk (V a R) models in order to assess their market risk exposure. The purpose of this paper is to estimate distribution functions of real estate V a R while taking into account non-normality in the distribution of returns. This is accomplished by the combination of the Cornish-Fisher expansion with a certain rearrangement procedure. We demonstrate that this combination allows superior estimation, and thus a better V a R estimate, than has previously been obtainable. We also show how the use of a rearrangement procedure solves well-known issues arising from the monotonicity assumption required for the Cornish-Fisher expansion to be applicable, a difficulty which has previously limited the useful of this expansion technique. Thus, practitioners can find a methodology here to quickly assess Value at Risk without suffering loss of relevancy due to any non-normality in their actual return distribution. The originality of this paper lies in our particular combination of Cornish-Fisher expansions and the rearrangement procedure.

Olefin cross-metathesis as a valuable tool for the preparation of renewable polyesters and polyamides from unsaturated fatty acid esters and carbamates

Olefin cross-metathesis of unsaturated fatty acid methyl ester (FAME) derived benzyl carbamates with methyl acrylate is described. The obtained by-product, an α,β-unsaturated ester, was further modified via thia-Michael addition reactions in order to synthesize branched AA-type or AB-type monomers for the preparation of polyesters, which are tuneable by oxidation. Cross-metathesis of fatty acid derived carbamates was used as a novel approach to prepare linear AB-type monomers, which can be used for the preparation of renewable polyamides PA11, PA12 and PA15. The necessary fatty acid carbamates were prepared by applying a catalytic Lossen rearrangement procedure. The presented synthesis strategy has potential for the bio-sourced preparation of monomers for the production of polyamides. All prepared polymers were fully characterized by NMR, SEC, and DSC analyses. Additionally, the Young's modulus of the prepared long-chain polyamide PA15 was determined.

Introducing Catalytic Lossen Rearrangements: Sustainable Access to Carbamates and Amines

AbstractA new, highly efficient and environmentally benign catalytic variant of the Lossen rearrangement is described. Dimethyl carbonate (DMC) as green activation reagent of hydroxamic acids in presence of catalytic amounts of tertiary amine bases {1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD), 1,8‐biazabicyclo 5.4.0 undec‐7‐ene (DBU), 1,4‐diazabicyclo[2.2.2]octane (DABCO), and triethylamine} and small quantities of methanol initiate the rearrangement. Methyl carbamates were obtained in good to moderate yields when aliphatic hydroxamic acids were employed in this catalytic Lossen rearrangement; under the same conditions aromatic hydroxamic acids yielded anilines. Notably, the mixture of DMC/methanol was recycled several times without observing decreased yields, thus minimizing the produced waste. Moreover, several other organic carbonates were successfully employed in the introduced catalytic Lossen rearrangement procedure.

ChemInform Abstract: An Improved Synthesis of a β‐Blocker Celiprolol Hydrochloride (X).

AbstractKey step in the sequence is an improved Fries rearrangement procedure to urea derivative (VII).

Six-membered cyclic nitronates as Brönsted bases: protonation and rearrangement into butyrolactone oximes

The protonation of six-membered cyclic nitronates (SMCNs) was studied by low-temperature NMR spectroscopy, and an efficient preparative procedure for acid-induced rearrangement of SMCNs into oximes of substituted butyrolactones was developed.

Synthesis of 5-bromo-2,4-dimethyloxazole by flash-vacuum pyrolysis of 2-acetyl-4-bromo-3-methylisoxazol-5(2H)-one

The photochemical or thermal loss of nitrogen and carbon dioxide from triazoles and isoxazol-5-ones, respectively, has been reported [1]. The photolysis [2] or pyrolysis [3, 4] of l-acyltriazoles leads to low yields of oxazoles as well as other products. However, Williams [5] has reported a new procedure for the thermal rearrangement of a number of acyltriazoles to oxazoles in good yields, although the procedure appears to be capable of variation only in the substituent at C-2. Since isoxazol-5-ones are readily prepared from β-keto esters and their equivalents [6, 7], the procedures described herein should represent a useful additional method for the preparation of oxazoles. The bromination of 3-methylisoxazol-5(4H)-one (1) with N-bromosuccinimide at room temperature gave 4-bromo-3-methylisoxazol5(2H)-one (2), which was converted to its N-acetyl derivative (3).

A “Rearrangement Procedure” For Scoring Adaptive Tests with Review Options

Because of the increased popularity of computerized adaptive testing (CAT), many admissions tests, as well as certification and licensure examinations, have been transformed from their paper-and-pencil versions to computerized adaptive versions. A major difference between paper-and-pencil tests and CAT from an examinee's point of view is that in many cases examinees are not allowed to revise their answers on CAT. Examinees prefer item review since they can correct misread or miskeyed items, while some researchers are afraid that examinees might try to use item review to cheat on the test. The purpose of this study was to test the efficiency of a rearrangement procedure that rearranged and skipped certain items to better estimate the examinees' abilities, without allowing them to cheat on the test. This was examined through a simulation study. The results showed that the rearrangement procedure was effective in reducing the bias of the ability estimates. The reliability slightly decreased after the procedure, but this decrease was negligible.

A high-capacity steganographic approach for 3D polygonal meshes

We present a high-capacity steganographic approach for three-dimensional (3D) polygonal meshes. We first use the representation information of a 3D model to embed messages. Our approach successfully combines both the spatial domain and the representation domain for steganography. In the spatial domain, every vertex of a 3D polygonal mesh can be represented by at least three bits using a modified multi-level embed procedure (MMLEP). In the representation domain, the representation order of vertices and polygons and even the topology information of polygons can be represented with an average of six bits per vertex using the proposed representation rearrangement procedure (RRP). Experimental results show that the proposed technique is efficient and secure, has high capacity and low distortion, and is robust against affine transformations. Our technique is a feasible alternative to other steganographic approaches.

Synthesis of 2,2′‐Diaminobischromones Using a Modified Procedure for the Rearrangement of 5‐(2‐Hydroxyphenyl)isoxazole to 2‐Aminochromone.

AbstractFor Abstract see ChemInform Abstract in Full Text.