Six-fold-symmetry internal rotation in toluenes: the low barrier challenge of 2,6-and 3,5-difluorotoluene

Pure six-fold symmetry (V6) internal rotation poses significant challenges to experimental and theoretical determination, as the very low torsional barriers result in huge tunneling splittings difficult to identify and to model. Here we resolved the methyl group internal rotation dynamics of 2,6- and 3,5-difluorotoluene using a newly developed computer code especially adapted to V6 problems. The jet-cooled rotational spectra of the title molecules in the 5–25 GHz region revealed internal rotation tunneling doublings of up to 3.6 GHz, which translated in methyl group potential barriers of V6 = 0.14872(24) and 0.0856(10) kJ mol−1, respectively, in the vibrational ground-state. Additional information on Stark effects and carbon isotopic species in natural abundance provided structural data and the electric dipole moments for both molecules. Ab initio calculations at the MP2 level do not reproduce the tiny torsional barriers, calling for experiments on other systems and additional theoretical models.DFGMINECO/CTQ2012-39132-C02-0

Reactivity and rotational spectra: The old concept of substitution effects

The internal rotation of methyl groups and nuclear quadrupole moments of the halogens Cl, Br, I in o-halotoluenes cause complex spectral fine and hyperfine structures in rotational spectra arising from angular momentum coupling. Building on the existing data regarding o-fluorotoluene and o-chlorotoluene, the investigations of o-bromotoluene and o-iodotoluene allow for a complete analysis of the homologous series of o-halogenated toluenes. The trend in the methyl barriers to internal rotation rising with the size of the halogen can be rationalised by repulsion effects as predicted by MP2 calculations. Furthermore, the analysis of the observed quadrupole coupling serves as a quantitative intra-molecular probe, e.g. for the explanation of the relative reaction yields in the nitration of halotoluenes, related to the different π-bond character of the C-X bond depending on the position of substitution

Conformational steering in dicarboxy acids: the native structure of succinic acid

Succinic acid, a dicarboxylic acid molecule, has been investigated spectroscopically with computational support to elucidate the complex aspects of its conformational composition. Due to the torsional freedom of the carbon backbone and hydroxy groups, a large number of potentially plausible conformers can be generated with an indication that the gauche conformer is favored over the trans form. The microwave and millimeter wave spectra have been analyzed and accurate spectroscopic constants have been derived that correlate best with those of the lowest energy gauche conformer. For an unambiguous conformational identification measurements were extended to the monosubstituted isotopologues, precisely determining the structural properties. Besides bond distances and angles, particularly the dihedral angle has been determined to be 67.76(11)°, confirming the anomalous tendency of the methylene units to favor gauche conformers when a short aliphatic segment is placed between two carbonyl groups.Spanish Ministry of Science and Innovation/CTQ2011-22923Spanish Ministry of Science and Innovation/CGL2011-2244

Nanoparticles: tech trends in healthcare

Nanotechnology is the use of matter on an atomic, molecular, and supramolecular scale for various purposes. Nanotechnology field of application is very much diverse which includes surface science, organic chemistry, molecular biology, semiconductor physics, energy storage, engineering, microfabrication, and molecular engineering. Its medical application ranges from biological devices, nano-electronic biosensors, and to future biological machines. The main issue nowadays for nanomedicine involve understanding the issues related to toxicity and environmental impact of nanoscale materials. Lot more functionalities can be added to nanomaterials by interfacing them with biological structures. The size of nanomaterials is similar most biological molecules and so useful for both in vivo and in vitro biomedical research and applications. The integration of nanomaterials with biology had paved path to the development of diagnostic devices, contrast agents, analytical tools, physical therapy applications and drug delivery vehicles

Joint geomorphological and geophysical (electrical resistivity) investigation for the configuration of soil pipe

Soil piping is a complex mechanism of subsurface soil erosion, which results underground conduits (cave/tunnel) of varying dimensions. Soil piping associates with severe consequences, such as land subsidence and land slide. Therefore, the investigation of soil pipe is crucial. However, the study of soil pipe is challenging unless characteristic surficial evidences of the pipe are available. Based on the surficial evidences, soil pipe can be configured with geophysical techniques which in-turn aid in designing precursory measures. Therefore, in the present study, we carried out a combined geomorphological and geophysical investigation to configure the soil pipe at Kinanoor village, Kasaragod, Kerala, India. Based on the vital geomorphological information, we carried out resistivity survey and configured an underground soil pipe of diameter ∼6.5 to 7 m that is seated ∼3 m beneath the surface. This hollow pipe is underlain by the only accessible road of that locality which makes the road vulnerable for transportation. Therefore, a bridge like structure is recommended to construct at the pipe location to stabilize the risk factor. Since the study area is situated on a fringe-slope, the geomorphological investigation points out that the disturbance in natural course of the drainage system and the accumulation of water in the up-slope area due to the man-made activities might act as potential causes for the piping in the area. Therefore, it is suggested not to disturb the natural course of the drainage which may lead to subsidence of the area in future

Cryoballoon pulmonary vein isolation as first-line treatment of typical atrial flutter: long-term outcomes of the CRAFT trial

\ua9 The Author(s) 2024.Background: CRAFT was an international, multicentre, randomised controlled trial across 11 sites in the United UK and Switzerland. Given the evidence that pulmonary vein triggers may be responsible for atrial flutter (AFL) as well as atrial fibrillation (AF), we hypothesised that cryoballoon pulmonary vein isolation (PVI) would provide greater symptomatic arrhythmia reduction than cavotricuspid isthmus (CTI) ablation, whilst also reducing the subsequent burden of AF. Twelve-month outcomes were previously reported. In this study, we report the extended outcomes of the CRAFT study to 36 months. Methods: Patients with typical AFL and no evidence of AF were randomised 1:1 to cryoballoon PVI or radiofrequency CTI. All patients received an implantable loop recorder (ILR) for continuous cardiac rhythm monitoring. The primary outcome was time-to-symptomatic arrhythmia recurrence > 30 s. Secondary outcomes included time-to-first-AF episode ≥ 2 min. The composite safety outcome included death, stroke and procedural complications. Results: A total of 113 patients were randomised to cryoballoon PVI (n = 54) or radiofrequency CTI ablation (n = 59). Ninety-one patients reconsented for extended follow-up beyond 12 months. There was no difference in the primary outcome between arms, with the primary outcome occurring in 12 PVI vs 11 CTI patients (HR 0.97; 95% CI 0.43–2.20; p = 0.994). AF ≥ 2 min was significantly less frequent in the PVI arm, affecting 26 PVI vs 36 CTI patients (HR 0.48; 95% CI 0.29–0.79; p = 0.004). The composite safety outcome occurred in 5 PVI and 6 CTI patients (p = 0.755). Conclusion: Cryoballoon PVI shows similar efficacy to radiofrequency CTI ablation in reducing symptomatic arrhythmia recurrence in patients presenting with isolated typical AFL but significantly reduces the occurrence of subsequent AF. Graphical Abstract: (Figure presented.)

Inhibition of measles virus replication by 5\u27-Norcarbocyclic nucleoside analogs

Despite intense efforts to increase vaccine coverage, measles virus (MV) still causes significant morbidity and mortality in the world, sometimes as the result of severe, chronic, lethal disease. In an effort to develop therapies to supplement immunization strategies, a number of 5′-nor carbocyclic adenosine analogues were evaluated for anti-MV activity in CV-1 monkey kidney cells. Of those compounds tested, those either unsubstituted at C4 or possessing a hydroxyl, azido or amino substituent at that position were the most active, with particularly significant inhibition of MV, strain Chicago-1. The EC50 values against this strain ranged from100 mg/ml in actively growing and stationary-phase cells. Results suggest that these compounds may be clinically useful anti-MV virus agents