ANTHEM: anatomically tailored hexagonal MRI

PURPOSE: This study aimed to investigate the use of anatomically tailored hexagonal sampling for scan-time and error reduction in MRI. MATERIALS AND METHODS: Anatomically tailored hexagonal MRI (ANTHEM), a method that combines hexagonal sampling with specific symmetry in anatomical geometry, is proposed. By using hexagonal sampling, aliasing artifacts are moved to regions where, due to the nature of the anatomy, aliasing is inconsequential. This can be used to either reduce scan time while maintaining spatial resolution or reduce residual errors in speedup techniques like UNFOLD and k-t BLAST/SENSE, which undersample k-space and unwrap fold-over artifacts during reconstruction. Computer simulations as well as phantom and volunteer studies were used to validate the theory. A simplified reconstruction algorithm for hexagonally sampled and subsampled k-space data was also used. RESULTS: A reduction in sampling density of 13.4% and 25% in each hexagonally sampled dimension was achieved for spherical and conical geometries without aliasing or reduction in spatial resolution. Optimal subsampling schemes that can be utilized by UNFOLD and k-t BLAST/SENSE were derived using hexagonal subsampling, which resulted in maximal, isotropic dispersal of the aliases. In combination with UNFOLD, ANTHEM was shown to move residual aliasing artifacts to the corners of the field of view, yielding reduced artifacts in CINE reconstructions. CONCLUSIONS: ANTHEM was successful in reducing acquisition time in conventional MRI and in reducing errors in UNFOLD imaging.     

Preparation and Diels-Alder chemistry of 4-vinylimidazoles

Various 4-vinylimidazole derivatives have been prepared from the corresponding 4-iodoimidazoles or from urocanic acid. Several methods for the elaboration of these vinylimidazoles and their Diels-Alder reactions are reported. All of the vinylimidazoles prepared in the course of this study react with N-phenylmaleimide quite readily with mild thermal activation providing a single cycloadduct, in most cases the initial, nonaromatic adduct. With more electron rich substrates, there is a tendency for these initial cycloadducts to undergo aromatization, ene reaction, and oxidation although this can be circumvented to a large extent by the choice of reaction conditions. Limited reactions were observed with other dienophiles, providing the expected cycloadducts in most cases, although an abnormal adduct was obtained in one case with dimethyl acetylene dicarboxylate. These substrates also participate in regioselective Diels-Alder reactions with monoactivated dienophiles, but require fairly forcing conditions, thus only providing the aromatized cycloadducts in modest yields. An investigation of substituent effects at the 2-position of the imidazole moiety was undertaken, in which electron-donating and weakly electron-withdrawing substituents are tolerated. In addition, several substrates with terminally substituted vinyl moieties have been investigated.     

Chemical Composition and Antimicrobial Activity of Essential Oil from Seeds of Pimpinella heyneana

Chemistry of Natural Compounds -     

FT-IR and FT-Raman study of Nasicon type phosphates, ASnFe(PO4)3 [A=Na2, Ca, Cd

FT-Raman and FT-IR spectra of ASnFe(PO4)3 [A=Na2, Ca, Cd] were recorded and analyzed. The bands were assigned in terms of the vibrational group frequencies of SnO6 octahedral and PO4 tetrahedral. The spectral analysis shows that the symmetry of corner shared octahedral (SnO6) and the tetrahedral (PO4) are lowered from their free ion symmetry state. The presence of Fe3+ ions disrupts the S-N-O-S-N chain in the structure. This causes distortion of SnO6 and PO4 in the structure of all the compounds. Also it is seen that there are two distinct PO4 tetrahedra of different P-O bond lengths. One of these tetrahedra is linearly distorted in all the title compounds. The PO4 frequencies and bond lengths are calculated theoretically and are in agreement with the experimental values. The presence of PO4 polyanion in the structure can reduce the redox energy and hence reduce the metal oxygen covalency strength in the structure.     

FT-IR, FT-Raman and quantum chemical calculations of (E)-N-carbamimidoyl-4-((3,4-dimethoxybenzylidene) amino) benzenesulfonamide

FT-IR and FT-Raman spectra of (E)-N-carbamimidoyl-4-((3,4-dimethoxybenzylidene) amino) benzenesulfonamide were recorded and analyzed. The vibrational wavenumbers were computed using HF/6-31G*, B3PW91/6-31G* and B3LYP/6-31G* basis. The data obtained from vibrational wavenumber calculations are used to assign vibrational bands obtained experimentally. The results indicate that the B3LYP method is able to provide satisfactory results for predicting vibrational frequencies and structural parameters. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of non-linear optics. The geometrical parameters of the title compound are in agreement with that of similar derivatives.     

Magnetic separation of green synthesized Fe3O4 nanoparticles on photocatalytic activity of methyl orange dye removal

The most frequent method of removing malignant growth-causing tones from current effluents before releasing them into water sources such as rivers, lakes, and groundwater has become standard. Traditional waste-water treatment frameworks have trouble getting rid of these contaminants. This is a unique flavonoid that uses Fe₃O₄ nanorods as photocatalytic agents to corrupt material tone in the watery stage utilizing observable light enlightenment. Green technique was used to amalgamate [email protected]₃O₄ nanorod like gems. Disappearance of the bright (UV) maintenance top at 565 nm confirmed the elimination of Methyl orange tone. After 110 min, the sensational shading disposal of Fe₃O₄ nanorod was observed to be 100%. This is due to photochemical redox process and the use of Fe₃O₄ nanorods with a high energy gap of flavonoids. The findings show that Fe₃O₄ rod-like gems manufactured using green technology are extremely valuable in the photocatalytic annihilation of hazardous contaminants.     

Synthesis and Biological Activity Studies of Some Novel Mannich Bases of Benzotriazolyl Triazoles

A series of substituted phenyl methyl piperazine triazolyl benzotriazoles 4a , 4b , 4c , 4d , 4e , 4f , 4g have been synthesized through the Mannich reaction of substituted phenyl triazolyl benzotriazoles 3a , 3b , 3c , 3d , 3e , 3f , 3g . The substituted phenyl triazolyl benzotriazoles were prepared from benzotriazolyl acetohydrazide, where the cyclization was facilitated through ammonium acetate and aryl aldehydes. The IR, ¹H NMR, mass spectral data and elemental analysis were performed to assign the structure. All the newly synthesized compounds were screened for their antimicrobial and antioxidant activity.     

Synthesis of Substituted (±)-3,4-Dihydrocoumarins Using H-Y Zeolite

Synthesis of substituted (±)-3,4 Dihydrocoumarins were prepared with the reaction between substituted cinnamic acid and phenol catalysed by ecofriendly solid-acid catalyst H-Y zeolite involving esterification followed by ring closure.     

Lipase Ps-C Catalysed Hydrolysis Of Aryl Deesters: A New Route To The Synthesis Of Achiral Half Esters

Pseudomonas cepacia lipase supported on ceramic particles (PS-C) offers a simple alternative route for the synthesis of achiral half esters, with very high yields, easy work up and remarkable substrate selectivity, as it cleaves only phenolic esters having a phenyl group (i.e. C₆H₅-O-CO-C₆H₅).     

An N-heterocyclic carbene-catalyzed [8 + 3] annulation of tropone and enals via homoenolate

A novel protocol for the annulation of tropone to enals involving nucleophilic heterocyclic carbene (NHC) catalyzed homoenolate formation has been developed. Interestingly, the reaction led to bicyclic delta-lactones instead of the expected gamma-spirolactones, presumably by the uncommon [8 + 3] annulation pathway. The strategy works well with a variety of enals.