A Convenient Synthesis of Difluoroalkyl Ethers from Thionoesters Using Silver(I) Fluoride

Herein we report the mild and rapid fluorodesulfurization of thionoesters using only silver(I) fluoride. This reaction demonstrates excellent functional group tolerance and complements existing strategies for difluoroalkyl ether synthesis, which rely on toxic and often dangerous reagents that demonstrate limited functional group compatibility. We additionally report the translation of this finding to the production of ¹⁸F-labelled difluoroalkyl ethers using fluoride-derived [¹⁸F]AgF. This new process should enable the synthesis of a wide range of difluoroalkyl ethers with applications in medicinal and materials chemistry, and radiotracer production.     

Effects of 780 nm diode laser irradiation on blood microcirculation: preliminary findings on time-dependent T1-weighted contrast-enhanced magnetic resonance imaging (MRI)

Laser therapy by low light doses shows promising results in the modulation of some cell functions. Various clinical studies indicate that laser therapy is a valuable method for pain treatment and the acceleration of wound healing. However, the mechanism behind it is still not completely understood. To explore the effect of a low-power diode laser (lambda = 780 nm) on normal skin tissue, time-dependent contrast enhancement has been determined by magnetic resonance imaging (MRI). In the examinations, six healthy volunteers (four male and two female) have been irradiated on their right planta pedis (sole of foot) with 5 J/cm2 at a fluence rate of 100 mW/cm2. T1-weighted magnetic resonance imaging is used to quantify the time-dependent local accumulation of Gadolinium-DPTA, its actual content in the local current blood volume as well as its distribution to the extracellular space. Images are obtained before and after the application of laser light. When laser light is applied the signal to noise ratio increases by more than 0.35 +/- 0.15 (range 0.23-0.63) after irradiation according to contrast-enhanced MRI. It can be observed that, after biomodulation with light of low energy and low power, wound healing improves and pain is reduced. This effect might be explained by an increased blood flow in this area. Therefore, the use of this kind of laser treatment might improve the outcome of other therapeutic modalities such as tumour ionizing radiation therapy and local chemotherapy.     

Preparation and characterization of MgB2 superconductor

The MgB₂ superconductor, synthesized using solid-state and liquid-phase sintering methods, have been characterized for various properties. The upper critical field, irreversibility line and critical current density have been determined using magnetization data. The current-voltage characteristics recorded under an applied magnetic field revealed the existence of vortex glass transition. The surface analysis using X-ray photoelectron spectroscopy shows that MgB₂ is sensitive to atmospheric degradation.     

Unterscheidung von gekochter und ungekochter Milch

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Control of asymmetric magnetic perturbations in tokamaks

The sensitivity of tokamak plasmas to very small deviations from the axisymmetry of the magnetic field |deltaB/B| approximately 10{-4} is well known. What was not understood until very recently is the importance of the perturbation to the plasma equilibrium in assessing the effects of externally produced asymmetries in the magnetic field, even far from a stability limit. DIII-D and NSTX experiments find that when the deleterious effects of asymmetries are mitigated, the external asymmetric field was often made stronger and had an increased interaction with the magnetic field of the unperturbed equilibrium. This Letter explains these counterintuitive results. The explanation using ideal perturbed equilibria has important implications for the control of field errors in all toroidal plasmas.     

Asymptotic analysis of the vibration spectrum of coupled Timoshenko beams with a dissipative joint

Complex flexible structures often are composed of simpler objects like beams joined end-to-end. We consider the case of two identical Timoshenko beams, coupled together at a typical energy-dissipating joint. The Wave Propagation Method of Keller and Rubinow is employed to compute the vibration spectrum of the system. It is found that the spectrum consists of a typical double-branched Timoshenko spectrum. In addition, however, for most combinations of energy-conserving end conditions, at least one of these branches decomposes into two sub-branches, one which is damped and one, undamped.     

Syntheses and crystal structures of a series of palladium(II) and platinum(II) complexes bearing new hydrazine-based bisphosphinite ligands equipped with pyridyl arms

This paper reports the synthesis of the hydrazine-based bisphosphinito ligands (RO)₂PN(Me)N(Me)P(OR)₂ (R = 2-hydroxy-6-methyl-pyridyl or 3-hydroxy-6-methyl-pyridyl) and their palladium and platinum complexes whose structures were unequivocally determined by X-ray crystallography.     

Pentosen und Methylpentosen

Ohne Zusammenfassung