1,721,083 research outputs found
Ricostruzione plastica delle Neoplasie del labbro
No full texted. Minerva medica- Torino
PMID: 208452
Concurrent Optimization of Organic Donor–Acceptor Pairs through Machine Learning
No full textIn this work an instance of the general problem occurring when optimizing multicomponent materials is treated: can components be optimized separately or the optimization should occur simultaneously? This problem is investigated from a computational perspective in the domain of donor–acceptor pairs for organic photovoltaics, since most experimental research reports optimization of each component separately. A collection of organic donors and acceptors recently analyzed is used to train nonlinear machine learning models of different families to predict the power conversion efficiency of donor–acceptor pairs, considering computed electronic and structural parameters of both components. The trained models are then used to predict photovoltaic performance for donor–acceptor combinations for which experimental data are not available in the data set. Data structure, and the usefulness of the trained models are critically assessed by predicting some donor–acceptor pairs that recently appeared in the literature, and the best combinations are proposed as worth investigating experimentally
Organic materials repurposing, a data set for theoretical predictions of new applications for existing compounds
Full text linkWe present a data set of 48182 organic semiconductors, constituted of molecules that were prepared with a documented synthetic pathway and are stable in solid state. We based our search on the Cambridge Structural Database, from which we selected semiconductors with a computational funnel procedure. For each entry we provide a set of electronic properties relevant for organic materials research, and the electronic wavefunction for further calculations and/or analyses. This data set has low bias because it was not built from a set of materials designed for organic electronics, and thus it provides an excellent starting point in the search of new applications for known materials, with a great potential for novel physical insight. The data set contains molecules used as benchmarks in many fields of organic materials research, allowing to test the reliability of computational screenings for the desired application, "rediscovering" well-known molecules. This is demonstrated by a series of different applications in the field of organic materials, confirming the potential for the repurposing of known organic molecules. © 2022. The Author(s)
The "case of Two Compounds with Similar Configuration but Nearly Mirror Image CD Spectra" Refuted. Reassignment of the Absolute Configuration of N-Formyl-3′,4′-dihydrospiro[indan-1,2′(1′H)-pyridine]
No full textIn 1997, Sandström and co-workers reported the case of two chiral spiro compounds with very similar skeletons but showing almost mirror-image electronic circular dichroism (ECD) spectra for the corresponding absolute configuration. The paper has been often cited as a proof and good educational example of the pronounced sensitivity of ECD toward molecular conformation, and a clear warning against the use of ECD spectral correlations to assign absolute configurations. Although both concepts remain valid, they are not exemplified by the quoted paper. We demonstrate that the original configurational assignment of one compound was wrong and revise it by using TDDFT calculations. The main reason for the observed failure is the use of the matrix method, a popular approach to predict ECD spectra of compounds which can be treated with an independent system approximation (ISA), including proteins. Using a modern version of the matrix method, we demonstrate that the ISA is not valid for the title compound. Even in the absence of apparent conjugation between the component chromophores, the validity of the ISA should never be taken for granted and the effective extent of orbital overlap should always be verified
Ultrastructural and histochemical study on the interrenal cells of the male stickleback (Gasterosteus aculeatus, Teleostea) in relation to the reproductive annual cycle.
No full textOn the arrangement of chromophores in light harvesting complexes: chance versus design
No full textWe used a homogeneous computational approach to derive the excitonic Hamiltonian for five light harvesting complexes containing only one type of chromophore and compare them in terms of statistical descriptors. We then studied the approximate exciton dynamics for the five complexes introducing a measure, the (averaged and time-dependent) inverse participation ratio, that enables the comparison between very diverse complexes on the same ground. We find that the global dynamics are very similar across the set of systems despite the variety of geometric structures of the complexes. In particular, the dynamics of four out of five light harvesting complexes are barely distinguishable with a small variation from the norm seen only for the Fenna–Matthews–Olson complex. We use the information from the realistic Hamiltonians to build a reduced model system that shows how the global dynamics are ultimately dominated by a single parameter, the degree of localization of the excitonic Hamiltonian eigenstates. Considering the physically plausible range of system parameters, the reduced model explains why the dynamics are so similar across most light harvesting complexes containing a single type of chromophore regardless of the detailed pattern of the inter-chromophore excitonic coupling
A simple dimeric model accounts for the vibronic ECD spectra of chiral polythiophenes in their aggregated states
No full textAggregates of chiral polythiophenes (PTs) show strong electronic circular dichroism (ECD) spectra with a unique vibronic structure. A computationally fast procedure, exploiting the quantum dynamics of the exciton-coupled electronic states of simple oligothiophene dimers as models of PT aggregates, is able to reproduce experimental vibronic ECD spectra of aggregated phases
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