Synthesis,Properties, and Remarkable 2 D Self‐Assembly at the Liquid/Solid Interface of a Series of Triskele‐Shaped 5,11,17‐Triazatrinaphthylenes (TrisK)

A series of 5,11,17‐triazatrinaphthylene (TrisK) derivatives, large disk‐like π‐conjugated molecules with C_3h symmetry, has been synthesised by following an optimised synthetic pathway. The synthesis was performed by a four‐step protocol based on the N‐arylation of 1,3,5‐tribromobenzene with appropriate anthranilate derivatives. This strategy permits the generation of either chlorinated ( TrisK‐Cl‐OCn ) or non‐chlorinated ( TrisK‐H‐OCn ) alkoxy‐substituted derivatives (OC_nH_2n+1 with n=3, 10, 12 and 16), thus providing additional versatility in the control of the structure–property relationships. The electronic properties of the various TrisK compounds have been characterised in solution by absorption and emission spectroscopies as well as cyclic voltammetry. The crystal structure of 2,8,14‐propyloxy‐5,11,17‐triazatrinaphthylene TrisK‐H‐OC3 has been determined by X‐ray diffraction analysis, which revealed the presence of stabilising weak intermolecular H bonds. Scanning tunnelling microscopy (STM) at the liquid/solid interface has revealed the remarkable 2D self‐assembling properties of the TrisK compounds. In particular, it has shown that TrisK‐H‐OC12 forms three concomitant self‐organised 2D phases with different row‐packing arrangements. This 2D polymorphism arises from slow ordering due to the presence of three long dodecyloxy chains on the molecular backbone. Individual molecules can be imaged with spectacular intramolecular resolution, thus providing the possibility of correlating the STM features with the calculated charge density distribution.     

Quantitative determination of 2-methoxy-3-isobutylpyrazine in red wines and grapes of Bordeaux using a stable isotope dilution assay.

Quantitative analysis of 2-methoxy-3-isobutylpyrazine (MIBP) in grapes and wines was developed, using a stable isotope dilution assay. This was applied to red grapes and wines from the Bordeaux region. The grapes and the wines of the 1995 and 1996 vintages came from the three most frequently used varieties of the region, Merlot, Cabernet Franc and Cabernet Sauvignon. The wines made from Cabernet Sauvignon grapes exhibited levels of MIBP (mean concentration, 12 ng l-1 for 1996 vintage and 13 ng l-1 for 1995 vintage) close to or higher than its odour threshold in wines (10 ng l-1) and slightly higher than the amounts found in the Merlot wines (mean concentration, 8 ng l-1 for 1996 vintage and 4 ng l-1 for 1995 vintage), especially those of the 1996 vintage. The variation in the levels of MIBP in grape samples and in their corresponding wines was monitored at four different stages towards the end of maturation. MIBP was present in all grapes and wines analysed, even in surmaturation. A linear trend was observed between grapes and wines of the three cultivars during maturation.     

Generalized Ising Model on a Scale-Free Network: An Interplay of Power Laws

We consider a recently introduced generalization of the Ising model in which individual spin strength can vary. The model is intended for analysis of ordering in systems comprising agents which, although matching in their binarity (i.e., maintaining the iconic Ising features of ‘+’ or ‘−’, ‘up’ or ‘down’, ‘yes’ or ‘no’), differ in their strength. To investigate the interplay between variable properties of nodes and interactions between them, we study the model on a complex network where both the spin strength and degree distributions are governed by power laws. We show that in the annealed network approximation, thermodynamic functions of the model are self-averaging and we obtain an exact solution for the partition function. This allows us derive the leading temperature and field dependencies of thermodynamic functions, their critical behavior, and logarithmic corrections at the interface of different phases. We find the delicate interplay of the two power laws leads to new universality classes.     

Peripheral waves generated in a cylindrical shell with hemispherical endcaps by a plane acoustic wave at axial incidence

The recently proposed approach [B. Dubus, A. Lavie, N.D. Veksler, J. Acoust. Soc. Am. 102 (1997) 3523-3529] of resonance order determination is applied to a steady-state problem of acoustic wave scattering by a cylindrical shell with hemispherical endcaps. In the intermediate frequency range, the main contribution in the form function is brought by two peripheral waves: zero-order symmetric Lamb-type wave S₀ and water-borne bending-type A wave. The resonance frequencies of these waves are found and the dispersion curves of the phase velocities computed. The influence of the relative length of the cylindrical part of the shell on the characteristics of peripheral waves is discussed.     

Modelling of Fluid/Paper Interaction in the Application Nip of a Film Coater

This paper describes a model for the penetration of fluid into a moving paper web in the application nip of a film coater. One-dimensional and two-dimensional solution methods are developed and compared. The two-dimensional model is solved using a Galerkin finite element method with a free surface algorithm. The depth of fluid penetration into the paper web increases with increase in applied pressure, paper permeability and exposure time. The fluid penetration depth decreases as the porosity or solution viscosity increases. The functional relationship among these variables depends on the profile of the pressure applied at the surface of the paper sheet. For the case of uniform paper permeability and no air compression in the web, the two-dimensional model gives similar results to the one-dimensional model.     

Estimating the Analytical Performance of Raman Spectroscopy for Quantification of Active Ingredients in Human Stratum Corneum

Confocal Raman microscopy (CRM) has become a versatile technique that can be applied routinely to monitor skin penetration of active molecules. In the present study, CRM coupled to multivariate analysis (namely PLSR—partial least squares regression) is used for the quantitative measurement of an active ingredient (AI) applied to isolated (ex vivo) human stratum corneum (SC), using systematically varied doses of resorcinol, as model compound, and the performance is quantified according to key figures of merit defined by regulatory bodies (ICH, FDA, and EMA). A methodology is thus demonstrated to establish the limit of detection (LOD), precision, accuracy, sensitivity (SEN), and selectivity (SEL) of the technique, and the performance according to these key figures of merit is compared to that of similar established methodologies, based on studies available in literature. First, principal components analysis (PCA) was used to examine the variability within the spectral data set collected. Second, ratios calculated from the area under the curve (AUC) of characteristic resorcinol and proteins/lipids bands (1400–1500 cm⁻¹) were used to perform linear regression analysis of the Raman spectra. Third, cross-validated PLSR analysis was applied to perform quantitative analysis in the fingerprint region. The AUC results show clearly that the intensities of Raman features in the spectra collected are linearly correlated to resorcinol concentrations in the SC (R² = 0.999) despite a heterogeneity in the distribution of the active molecule in the samples. The Root Mean Square Error of Cross-Validation (RMSECV) (0.017 mg resorcinol/mg SC), The Root Mean Square of Prediction (RMSEP) (0.015 mg resorcinol/mg SC), and R² (0.971) demonstrate the reliability of the linear regression constructed, enabling accurate quantification of resorcinol. Furthermore, the results have enabled the determination, for the first time, of numerical criteria to estimate analytical performances of CRM, including LOD, precision using bias corrected mean square error prediction (BCMSEP), sensitivity, and selectivity, for quantification of the performance of the analytical technique. This is one step further towards demonstrating that Raman spectroscopy complies with international guidelines and to establishing the technique as a reference and approved tool for permeation studies.     

Push–Pull Derivatives Based on 2,4′-Biphenylene Linker with Quinoxaline, [1,2,5]Oxadiazolo[3,4-B]Pyrazine and [1,2,5]Thiadiazolo[3,4-B]Pyrazine Electron Withdrawing Parts

A series of novel V-shaped quinoxaline, [1,2,5]oxadiazolo[3,4-b]pyrazine and [1,2,5]thiadiazolo[3,4-b]pyrazine push–pull derivatives with 2,4′-biphenylene linker were designed and their electrochemical, photophysical and nonlinear optical properties were investigated. [1,2,5]Oxadiazolo[3,4-b]pyrazine is the stronger electron-withdrawing fragment as shown by electrochemical, and photophysical data. All compounds are emissive in a solid-state (from the cyan to red region of the spectrum) and quinoxaline derivatives are emissions in DCM solution. It has been found that quinoxaline derivatives demonstrate important solvatochromism and extra-large Stokes shifts, characteristic of twisted intramolecular charge transfer excited state as well as aggregation induced emission. The experimental conclusions have been justified by theoretical (TD-)DFT calculations.     

Use of Passive and Grab Sampling and High-Resolution Mass Spectrometry for Non-Targeted Analysis of Emerging Contaminants and Their Semi-Quantification in Water

Different groups of organic micropollutants including pharmaceuticals and pesticides have emerged in the environment in the last years, resulting in a rise in environmental and human health risks. In order to face up and evaluate these risks, there is an increasing need to assess their occurrence in the environment. Therefore, many studies in the past couple of decades were focused on the improvements in organic micropollutants’ extraction efficiency from the different environmental matrices, as well as their mass spectrometry detection parameters and acquisition modes. This paper presents different sampling methodologies and high-resolution mass spectrometry-based non-target screening workflows for the identification of pharmaceuticals, pesticides, and their transformation products in different kinds of water (domestic wastewater and river water). Identification confidence was increased including retention time prediction in the workflow. The applied methodology, using a passive sampling technique, allowed for the identification of 85 and 47 contaminants in the wastewater effluent and river water, respectively. Finally, contaminants’ prioritization was performed through semi-quantification in grab samples as a fundamental step for monitoring schemes.     

Spatial microheterogeneity in the valence band of mixed halide hybrid perovskite materials

The valence band of lead halide hybrid perovskites with a mixed I/Br composition is investigated using electronic structure calculations and complementarily probed with hard X-ray photoelectron spectroscopy. In the latter, we used high photon energies giving element sensitivity to the heavy lead and halide ions and we observe distinct trends in the valence band as a function of the I : Br ratio. Through electronic structure calculations, we show that the spectral trends with overall composition can be understood in terms of variations in the local environment of neighboring halide ions. From the computational model supported by the experimental evidence, a picture of the microheterogeneity in the valence band maximum emerges. The microheterogeneity in the valence band suggests that additional charge transport mechanisms might be active in lead mixed halide hybrid perovskites, which could be described in terms of percolation pathways.

Microheterogeneity in valence band maximum of hybrid perovskites with mixed I/Br composition. Theoretical calculations show that trends in hard X-ray photoelectron spectroscopy with overall composition are related to variations in local environment.