Identification of volatiles from oxidised phosphatidylcholine molecular species using headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC-MS)

Headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry analysis (GC-MS) was used to investigate the volatile compounds from oxidised phosphatidylcholine molecular species. 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) and 1-stearoyl-2-linoleoyl-sn-glycero-3-phosphocholine (SLPC) were chosen as models. The influence of several parameters on the efficiency of volatile oxidised compounds (VOCs) microextraction, such as type of fibre, extraction duration and temperature were studied. The best results were obtained with a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre used at 50 °C during 25 min. The effect of oxidation temperature on the yield of VOCs from SOPC and SLPC was investigated. Oxidative kinetics of SOPC and SLPC were investigated by measuring both the production of VOCs and the degradation of starting materials. More than 30 VOCs were detected by means of the reference mass spectra of the National Institute of Standards and Technology mass spectral library, and most of them were further confirmed by comparing their mass spectra and retention time with those obtained from authentic reference compounds under the same analytical conditions. Moreover, the origins of VOCs from oxidised PLs were studied by comparing those obtained from their corresponding triacylglycerides under the same experimental conditions. The main VOCs identified from oxidised SOPC were (E)-2-decenal, nonanal and octanal and from oxidised SLPC were (E)-2-heptenal, (E)-2-octenal and (E, E)-2,4-decadienal. The proposed method was applied to a real food sample, soy lecithin.

Photochemical Properties and Activity of Water‐Soluble Polymer/C60 Nanohybrids for Photodynamic Therapy

Water‐soluble star‐like poly(vinyl alcohol)/C₆₀ and poly{[poly(ethylene glycol) acrylate]‐co‐(vinyl acetate)}/C₆₀ nanohybrids are prepared by grafting macroradicals onto C₆₀ and are assessed as photosensitizers for photodynamic therapy. The photophysical and biological properties of both nanohybrids highlight key characteristics influencing their overall efficiency. The macromolecular structure (linear/graft) and nature (presence/absence of hydroxyl groups) of the polymeric arms respectively impact the photodynamic activity and the stealthiness of the nanohybrids. The advantages of both nanohybrids are encountered in a third one, poly[(N‐vinylpyrrolidone)‐co‐(vinyl acetate)]/C₆₀, which has linear grafts without hydroxyl groups, and shows a better photodynamic activity.

     

B?H,C?H,and B?C Bond Activation: The Role of Two Adjacent Agostic Interactions

Tuning the nature of the linker in a L∼BHR phosphinoborane compound led to the isolation of a ruthenium complex stabilized by two adjacent, δ‐C H and ε‐B_sp2 H, agostic interactions. Such a unique coordination mode stabilizes a 14‐electron “RuH₂P₂” fragment through connected σ‐bonds of different polarity, and affords selective B H, C H, and B C bond activation as illustrated by reactivity studies with H₂ and boranes.     

A Novel One- and Zero-Dimensional Model for Turbulent Jet Ignition

Flow, Turbulence and Combustion - Turbulent jet ignition (TJI) is a promising combustion technology for burning highly diluted air-fuel mixtures. Computationally efficient models to assess the...     

Role of Stone–Wales defects on the functionalization of (8,0) single wall carbon nanotubes by the amine group: Ab initio study

Using first-principle calculations, we have investigated the chemical functionalization of (8,0) zigzag single wall carbon nanotubes (SWNTs) by the amine group on Stone–Wales (SW) defects. The binding of NH₂ with the defective (8,0) nanotube was explored and the preferential grafting sites have been identified. On the other hand, the modifications induced by SW defect and functional groups in the structural and electronic properties of (8,0) SWNT have also been investigated. The role of SW defects in the chemical reactivity of carbon nanotubes was well identified.     

Auditory discrimination of force of impact

The auditory discrimination of force of impact was measured for three groups of listeners using sounds synthesized according to first-order equations of motion for the homogenous, isotropic bar [Morse and Ingard (1968). Theoretical Acoustics pp. 175-191]. The three groups were professional percussionists, nonmusicians, and individuals recruited from the general population without regard to musical background. In the two-interval, forced-choice procedure, listeners chose the sound corresponding to the greater force of impact as the length of the bar varied from one presentation to the next. From the equations of motion, a maximum-likelihood test for the task was determined to be of the form Δlog A + αΔ log f > 0, where A and f are the amplitude and frequency of any one partial and α = 0.5. Relative decision weights on Δ log f were obtained from the trial-by-trial responses of listeners and compared to α. Percussionists generally outperformed the other groups; however, the obtained decision weights of all listeners deviated significantly from α and showed variability within groups far in excess of the variability associated with replication. Providing correct feedback after each trial had little effect on the decision weights. The variability in these measures was comparable to that seen in studies involving the auditory discrimination of other source attributes.     

Nanoscale self-organization using standing surface acoustic waves

The diffusion of an adatom on a substrate submitted to a standing surface acoustic wave is theoretically studied. By performing large scale molecular dynamic simulations, we show that the wave dynamically structures the substrate by encouraging the presence of the adatom in the vicinity of the maximum displacements of the substrate. Using an analytical model, we explain this feature introducing an effective potential induced by the wave. Applied in an atomic deposition experiment, this dynamic structuring process should govern the nucleation sites distribution opening the route to accurately control the self-organization process at the nanoscale.     

Higher-order modulation instability in nonlinear fiber optics

We report theoretical, numerical, and experimental studies of higher-order modulation instability in the focusing nonlinear Schr?dinger equation. This higher-order instability arises from the nonlinear superposition of elementary instabilities, associated with initial single breather evolution followed by a regime of complex, yet deterministic, pulse splitting. We analytically describe the process using the Darboux transformation and compare with experiments in optical fiber. We show how a suitably low frequency modulation on a continuous wave field induces higher-order modulation instability splitting with the pulse characteristics at different phases of evolution related by a simple scaling relationship. We anticipate that similar processes are likely to be observed in many other systems including plasmas, Bose-Einstein condensates, and deep water waves.     

Dynamics and thermodynamics of the low-temperature strongly interacting Bose gas

We measure the zero-temperature equation of state of a homogeneous Bose gas of (7)Li atoms by analyzing the in situ density distributions of trapped samples. For increasing repulsive interactions our data show a clear departure from mean-field theory and provide a quantitative test of the many-body corrections first predicted in 1957 by Lee, Huang, and Yang [Phys. Rev. 106, 1135 (1957).]. We further probe the dynamic response of the Bose gas to a varying interaction strength and compare it to simple theoretical models. We deduce a lower bound for the value of the universal constant ξ > 0.44(8) that would characterize the universal Bose gas at the unitary limit.     

Giant charge relaxation resistance in the Anderson model

We investigate the dynamical charge response of the Anderson model viewed as a quantum RC circuit. Applying a low-energy effective Fermi liquid theory, a generalized Korringa-Shiba formula is derived at zero temperature, and the charge relaxation resistance is expressed solely in terms of static susceptibilities which are accessible by Bethe ansatz. We identify a giant charge relaxation resistance at intermediate magnetic fields related to the destruction of the Kondo singlet. The scaling properties of this peak are computed analytically in the Kondo regime. We also show that the resistance peak fades away at the particle-hole symmetric point.