Chiral microneedles from an achiral bis(boron dipyrromethene): spontaneous mirror symmetry breaking leading to a promising photoluminescent organic material

Supramolecular self-assembly of a highly flexible and achiral meso bis(boron dipyrromethene) [bis-(BODIPY)] dye straightforwardly yields fluorescent micro-fibers, exhibiting an intriguing anisotropic photonic behavior. This performance includes the generation of chiroptical activity owing to spontaneous mirror symmetry breaking (SMSB). Repetition of several self-assembly experiments demonstrates that the involved SMSB is not stochastic but quasi deterministic in the direction of the induced chiral asymmetry. The origin of these intriguing (chiro)photonic properties is revealed by fluorescent microspectroscopy studies of individual micrometric objects, combined with X-ray diffraction elucidation of microcrystals. Such a study demonstrates that J-like excitonic coupling between bis(BODIPY) units plays a fundamental role in their supramolecular organization, leading to axial chirality. Interestingly, the photonic behavior of the obtained fibers is ruled by inherent nonradiative pathways from the involved push-pull chromophores, and mainly by the complex excitonic interactions induced by their anisotropic supramolecular organization

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

Separation of Isoeugenol from Methylcyclohexane as a Model Mixture of Biojet Fuel Purification: Solvent Selection and Liquid–Liquid Equilibrium

The biorefinery concept emerged as an opportunity to reduce the negative effects of climate change and as a potential source of products for the fuel industry, where jet fuel produced by hydrodeoxygenation of bio-oil (denominated as biojet fuel) is of special interest. However, the presence of highly oxygenated species makes this kind of jet fuel unsuitable as a final product. Thus, it is necessary to remove phenolic compounds from its complex matrix, but the study of solvent extraction of phenolic compounds as an upgrading of a bio-oil matrix requires a thermodynamic framework to reduce the experimental effort. In this work, isoeugenol was selected as a model phenolic molecule from biojet fuel, while methylcyclohexane was selected as a representative cyclic alkane solvent from jet fuel. Three solvents were selected by a screening based on a conductor-like screening model for real solvents (COSMO-RS) to test their capability to extract isoeugenol from methylcyclohexane. The selected solvents were ethylene glycol, diethylene glycol, and 1,3-propanediol. The density and viscosity were measured for all pure compounds and the mixtures of isoeugenol + (methylcyclohexane or extracting solvent) at 101.3 kPa and temperatures from 293.15 to 333.15 K. The liquid–liquid equilibrium was also measured for all the systems of isoeugenol + methylcyclohexane + extracting solvent at 101.3 kPa and 313.15 K. Density and liquid–liquid equilibrium data were modeled with perturbed-chain statistical associating fluid theory (PC-SAFT). Viscosity was modeled using the PC-SAFT + entropy scaling theory. The results indicate that isoeugenol has a higher affinity with the selected extracting solvents than methylcyclohexane, since the excess volume for binary mixtures of isoeugenol + extracting solvent exhibits negative values, while isoeugenol + methylcyclohexane exhibits mainly positive values. The selectivity and distribution coefficient values obtained support the idea that selected solvents are good for extracting isoeugenol, where diethylene glycol is the best alternative. PC-SAFT accurately represents the liquid–liquid equilibrium with only binary interaction parameters between methylcyclohexane and the selected solvents. Then, this model can be used as a tool for the analysis and simulation of processes of isoeugenol separation in more complex liquid mixtures

Improved Multifrequency Phase-Modulation Method That Uses Rectangular-Wave Signals to Increase Accuracy in Luminescence Spectroscopy

We propose a novel multifrequency phase-modulation method for luminescence spectroscopy that uses a rectangular-wave modulated excitation source with a short duty cycle. It is used for obtaining more detailed information about the luminescence system: the information provided by different harmonics allows estimating a model for describing the global frequency response of the luminescent system for a wide range of analyte concentration and frequencies. Additionally, the proposed method improves the accuracy in determination of the analyte concentration. This improvement is based on a simple algorithm that combines multifrequency information provided by the different harmonics of the rectangular-wave signal, which can be easily implemented in existing photoluminescence instruments by replacing the excitation light source (short duty cycle rectangular signal instead of sinusoidal signal) and performing appropriate digital signal processing after the transducer (implemented in software). These claims have been demonstrated by using a well-known oxygen-sensing film coated at the end of an optical fiber [a Pt­(II) porphyrin immobilized in polystyrene]. These experimental results show that use of the proposed multifrequency phase-modulation method (1) provides adequate modeling of the global response of the luminescent system (<i>R</i>² > 0.9996) and (2) decreases the root-mean-square error in analytical determination (from 0.1627 to 0.0128 kPa at 0.5 kPa O₂ and from 0.9393 to 0.1532 kPa at 20 kPa O₂) in comparison with a conventional phase-modulation method based on a sinusoidally modulated excitation source (under equal luminous power conditions)

Two-particle Bose-Einstein correlations and their Lévy parameters in PbPb collisions at sNN\sqrt{s_\mathrm{NN}} = 5.02 TeV

Two-particle Bose-Einstein momentum correlation functions are studied for charged-hadron pairs in lead-lead collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV. The data sample, containing 4.27$\times10^{9}$ minimum bias events corresponding to an integrated luminosity of 0.607 nb$^{-1}$, was collected by the CMS experiment in 2018. The experimental results are discussed in terms of a L\'evy-type source distribution. The parameters of this distribution are extracted as functions of particle pair average transverse mass and collision centrality. These parameters include the L\'evy index or shape parameter ($\alpha$), the L\'evy scale parameter ($R$), and the correlation strength parameter ($\lambda$). The source shape, characterized by $\alpha$, is found to be neither Cauchy nor Gaussian, implying the need for a full L\'evy analysis. Similarly to what was previously found for systems characterized by Gaussian source radii, a hydrodynamical scaling is observed for the L\'evy $R$ parameter. The $\lambda$ parameter is studied in terms of the core-halo model.Comment: Submitted to Physical Review C. All figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/HIN-21-011 (CMS Public Pages