1,3-Oxazepane-4,7-Diones Compounds: 1Hand 13CNMR High-Resolution Spectroscopy (1D and 2D)

“Oxazepine” refers to any seven-membered ring containing an oxygen and nitrogen atom. The 1,3-oxazepine is a branch of many types of the heterocyclic oxazepine [1–7]. The core structure of 1,3-oxazepane-4,7diones consists of a sevenmemebred ring along with two carbonyl group. Over the years, the syntheses of oxazepine derivatives have been investigated and documented. The result is important of heterocyclic compounds having significant biological uses [8– 13]. Recently, we prepared a variety of 1,3-oxazepinediones in order to study the spectroscopic and liquid crystal properties [14]. In this paper, we present the structural elucidation by 1D and 2D NMR experiments of 3-alkyl- 2-(3-hydroxyphenyl)-1,3-oxazepane-4,7-diones with general formula(HOC6H4)CONCnH2n+1CH-CH(CO)2 (where n = 2, 4, 6, 8, 10, 12, 14, 16, and 18). Here, the hydroxyphenyl and the terminal alkyl chain are attached to the oxazepane ring

New mesogenic compounds possessing a biphenyl ester and ether moiety comprising 1,3-dimethylbarbituric acid: synthesis, characterisation and mesomorphic studies

New substituted derivatives of 5-vinyl-1,3-dimethylbarbituric acid were synthesised and evaluated for liquid crystal properties. Two sets of molecules were prepared. One end of all the molecules possesses the 1,3-dimethylbarbituric core. The first set comprises biphenyl ethers, 4a–n and the second set biphenyl esters, 5a–g. Liquid crystalline properties were investigated by POM and DSC techniques. All the compounds exhibited enantiotropic smectic A and nematic mesophases. The LC properties were found to depend on the spacer and terminal alkoxy- chain and alkoxy- ester moiety of the molecules. Smaller alkyl chain members showed a smectic phase, while higher alkyl chain members showed a nematic phase

Synthesis mesomorphic and theoretical studies of some new unsymmetrical dimeric ethers of 6-amino-1,3-dimethyluracil and biphenyl cores

New sets of unsymmetric calamitic molecules with uracil unit at one end and biphenyl core at another end were synthesized. Liquid crystal property of these molecules was investigated by POM and DSC techniques. All compounds exhibit LC property depending on the spacer and terminal alkoxy chain of the molecules. First set shows smectic phase in lower members and nematic phase appeared in higher members. The second set favour nematic liquid crystalline phase with respect to spacer alkyl chain length. Molecules are escaped from the planarity as a result disturbing the layer stacking leads to nematic phase in higher analogues. Theoretical studies have been performed for all the compounds and are found to be in agreement with the results of the current studies

On structure identification of parallel Wiener-Hammerstein models

In this paper, models composed of parallel branches of the Wiener-Hammerstein type are studied. Using a zero-mean stationary white Gaussian sequence as input to such models, their structure can be identified by considering the bispectrum of the output sequence. Simulation examples are included to illustrate the results of the pape

On structure identification of parallel Wiener-Hammerstein models

In this paper, models composed of parallel branches of the Wiener-Hammerstein type are studied. Using a zero-mean stationary white Gaussian sequence as input to such models, their structure can be identified by considering the bispectrum of the output sequence. Simulation examples are included to illustrate the results of the pape

Discrepancy in MALDI-TOF MS identification of uncommon Gram-negative bacteria from lower respiratory secretions in patients with cystic fibrosis.

Early identification of microbial organisms from respiratory secretions of patients with cystic fibrosis (CF) is important to guide therapeutic decisions. The objective was to compare the accuracy of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) relative to the conventional phenotypic method in identifying common bacterial isolates, including nonfermenting Gram-negative bacteria, in a cohort of patients with CF. A total of 123 isolates from 50 patients with CF representing 14 bacterial species from respiratory specimens were identified using MALDI-TOF MS in parallel with conventional phenotypic methods. Discrepancies were confirmed by 16S ribosomal RNA (rRNA) gene sequencing in five Gram-negative isolates. The MALDI-TOF MS managed to identify 122/123 (99.2%) bacterial isolates to the genus level and 118/123 (95.9%) were identified to the species level. The MALDI-TOF MS results were 100% consistent to the species level with conventional phenotypic identification for isolates of Staphylococcus aureus, Pseudomonas aeruginosa, Haemophilus influenzae, Streptococcus pyogenes, Achromobacter xylosoxidans, Stenotrophomonas maltophilia, and other uncommon organisms such as Chryseobacterium gleum and Enterobacter cloacae. The 5/123 (4.6%) isolates misidentified were all Gram-negative bacteria. The isolation of E. cloacae and Haemophilus paraphrohaemolyticus may extend the potentially pathogenic list of organisms isolated from patients with CF. Although the technique provides an early identification and antimicrobial therapy approach in patients with CF, limitation in the diagnosis of uncommon Gram-negative bacteria may exist

Structure identification of a class of non-linear systems using correlation and bispectrum approaches

The class of nonlinear systems studied in this paper is assumed to be modeled by block-cascades. Such cascades are composed of a dynamic linear block (L) in cascade with a zero-memory nonlinear block (N) followed by another dynamic linear block (L). This class of models is extensively used to represent nonlinear dynamic systems and is known in the literature as Wiener-Hammerstein models. Using a zero-mean stationary white Gaussian process as an input to such models, a structure identification criterion is developed based on the bispectrum and bicoherence of the output sequence only. A comparison between the developed criterion and other cross-correlation based criterion is given