Tereoselective total synthesis of racemic grandisol : An improved convenient procedure

(±) Grandisol has been stereoselectively synthesized in a 31% overall yield by a practical and convenient procedure employing the Salomon photobicyclization as the key-step.     

Changes in cerebral activity after decreased upper-limb hypertonus: an EMG-fMRI study

Objective

Whereas several studies have used functional magnetic resonance imaging (fMRI) to investigate motor recovery, whether therapy to decrease post-stroke hypertonus alters central motor patterns remains unclear. In this study, we used continuous electromyography (EMG)-fMRI to investigate possible changes in movement-related brain activation in patients receiving Botulinum toxin (BoNT-A) for hand-muscle hypertonus after chronic stroke.

Methods

We studied eight stroke patients all of whom had hemiparesis and associated upper-limb hypertonus. All patients underwent an fMRI-EMG recording and clinical-neurological assessment before BoNT-A and 5 weeks thereafter. The handgrip motor task during imaging was fixed across both patients and controls. The movements were metronome paced, movement amplitude and force were controlled with a plastic orthosis, dynamometer and EMG recording. An age-matched control group was recruited from among healthy volunteers underwent the same fMRI-EMG recording.

Results

Before BoNT-A, while patients moved the paretic hand, fMRI detected wide bilateral activation in the sensorymotor areas (SM1), in the supplementary motor area (SMA) and cerebellum. After BoNT-A blood oxygenation level-dependent (BOLD) activation decreased in ipsilateral and contralateral motor areas and became more lateralized. BOLD activation decreased also in ipsilateral cerebellar regions and in the SMA.

Conclusion

Changes in peripheral upper-limb hypertonus after BoNT-A were associated to an improvement in active movements and more lateralized and focalized activation of motor areas. The clinical and EMG-fMRI coregistration technique we used to study hand-muscle hypertonus in patients receiving BoNT-A after chronic stroke should be useful in future studies seeking improved strategies for post-stroke neurorehabilitation.     

Brain oscillatory activity during motor imagery in EEG-fMRI coregistration

The purpose of the present work was to investigate the correlation between topographical changes in brain oscillatory activity and the blood oxygenation level-dependent (BOLD) signal during a motor imagery (MI) task using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) coregistration.     

Nonaffine deformation of inherent structure as a static signature of cooperativity in supercooled liquids

We unveil the existence of nonaffinely rearranging regions in the inherent structures (IS) of supercooled liquids by numerical simulations of model glass formers subject to static shear deformations combined with local energy minimizations. In the liquid state IS, we find a broad distribution of large rearrangements which are correlated only over small distances. At low temperatures, the onset of the cooperative dynamics corresponds to much smaller displacements correlated over larger distances. This finding indicates the presence of nonaffinely rearranging domains of relevant size in the IS deformation, which can be seen as the static counterpart of the cooperatively rearranging regions in the dynamics. This idea provides new insight into possible structural signatures of slow cooperative dynamics of supercooled liquids and supports the connections with elastic heterogeneities found in amorphous solids.     

Colloidal Surface Active Maghemite Nanoparticles for Biologically Safe CrVI Remediation: from Core‐Shell Nanostructures to Pilot Plant Development

The present study is aimed at the exploration of achievable improvements for Cr^VI ex situ and in situ water remediation by using novel naked colloidal maghemite (γ‐Fe₂O₃) nanoparticles (surface active maghemite nanoparticles, SAMNs). The reliability of SAMNs for Cr^VI binding and removal was demonstrated, and SAMN@Cr^VI complex was characterized, as well as the covalent nature of the absorption was unequivocally proved. SAMNs were structurally and magnetically well conserved after Cr^VI binding. Thus, in consideration of their affinity for Cr^VI, SAMNs were exploited in a biological model system, mimicking a real in situ application. The assay evidenced a progressive reduction of revertant colonies of Salmonella typhimurium TA100 strain, as maghemite nanoparticles concentration increased, till the complete suppression of Cr^VI mutagen effect. Finally, an automatic modular pilot system for continuous magnetic removal and recovery of Cr^VI from water is proposed. SAMNs, thanks to their colloidal, binding, and catalytic properties, represent a promising tool as a reliable nanomaterial for water remediation by Cr^VI.     

Preparation of second generation ionic liquids by efficient solvent-free alkylation of N-heterocycles with chloroalkanes

Non-conventional techniques, such as microwave (MW) and power ultrasound (US) as well as combined MW/US irradiation, have been used to promote one-pot synthesis of second-generation ionic liquids (ILs), cutting down reaction times and improving yields. However, the use of chloroalkanes in the alkylation of N-heterocycles requires more drastic conditions if results are to match those obtained with more reactive alkyl halides. The present paper describes a series of MW- or MW/US-promoted IL preparations starting from chloroalkanes and classic heterocycles (1-methylimidazole, pyridine and 1-methylpyrrolidine). When reactions were carried out under conventional heating in an oil bath they required longer reaction times and gave poorer yields. (1)H-NMR analysis and ion-exchange chromatography showed that the present solventless procedure afforded ILs of satisfactory purity. The observed high yields (usually 70-98% isolated), and short reaction times showed that a straightforward access to ILs can be also achieved with the use of alkyl chlorides, resulting in a considerable reduction of costs.     

NMR study of the reversible trapping of SF6 by cucurbit[6]uril in aqueous solution

The complexation of sulfur hexafluoride (SF(6)), a highly potent greenhouse gas, by cucurbit[6]uril (CB) was studied at various temperatures in Na(2)SO(4) aqueous solutions by (19)F and (1)H NMR. CB shows a remarkable affinity for SF(6), suggesting that it is a suitable molecular container for the design of materials tailored for SF(6) trapping. At 298 K, the equilibrium constant characterizing the inclusion of SF(6) by CB is 3.1 x 10(4) M(-1) and the residence time of SF(6) within the CB cavity is estimated to be of the order of a few seconds. The enthalpic and entropic contributions to the free energy of encapsulation were determined and are discussed. This work also reports on the interest of SF(6) in the framework of the spin-spy methodology. The advantages and drawbacks of solution-state (19)F NMR of SF(6) with respect to (129)Xe NMR are discussed. SF(6) comes forward as a versatile and informative spin-spy molecule for probing systems in solution because its detection limit by (19)F NMR reaches the micromolar range with standard equipment and because quantitative integral measurements, relaxation time measurements, and demanding experiments, such as translational diffusion coefficient measurements, are easily carried out in addition to chemical shift measurements. Solution-state (19)F NMR of SF(6) emerges as a promising alternative to (129)Xe NMR for probing cavities and for other applications relying on the encapsulation of an NMR active gaseous probe.     

Rapid and sensitive analysis of vincristine in human plasma using on-line extraction combined with liquid chromatography/tandem mass spectrometry

A simple and rapid method has been developed and validated for the quantitation of vincristine in human plasma by liquid chromatography/tandem mass spectrometry (LC/MS/MS) with atmospheric pressure chemical ionization using on-line solid-phase extraction. The method uses vinblastine as internal standard and the sample preparation is limited just to a plasma protein precipitation step. Further sample clean-up is carried out on-line through a perfusion column preceding an analytical phenyl LC column, the latter directly connected to the mass spectrometer. Quantitation is performed in multiple reaction monitoring mode using the transitions of m/z 825.3 --> 765.3 and 811.3 --> 751.3 for vincristine and vinblastine respectively. The assay was linear (r2 > or =0.99) in a concentration range from 0.1 to 500 ng/mL. Carry-over, measured on the experimental set-up, was less than 0.04%. Recovery for vincristine and the internal standard was within 90-95%. The intra-day and inter-day assay precision ranged from 1.2% to 6.8% RSD while mean percentage deviation from nominal value ranged from 0.01% to 6.1%. The proposed assay was found suitable for pharmacokinetics investigations and clinical therapeutic drug monitoring especially in pediatric cancer patients.     

Highly Conjugated Bis(benzo[b]phosphole)-P-oxides: Synthesis and Electrochemical,Optical, and Computational Studies

The first examples of a π-conjugated benzo[b]phosphole P-oxide in which two phosphole P-oxide units are connected by a carbon-carbon double bond are described. The molecules are synthesized as E isomers with respect to the carbon-carbon double bond and exist as stable cis and trans isomers (chiral and meso one respectively) relatively to the two stereogenic P atoms. The optical and electrochemical properties of both isomers have been investigated by experiment and computations.