Toward Efficient Modeling of Nonradiative Decay in Extended INVEST: Overcoming Computational Challenges in Quantum Dynamics Simulations.

In recent years, an increasing number of fully organic molecules capable of thermally activated delayed fluorescence (TADF) have been reported, often with very small or even inverted singlet-triplet (INVEST) energy gaps. These molecules typically exhibit complex photophysics due to the close energy levels of multiple singlet and triplet states, which create various transition pathways toward emission. A predictive model for the rates of these transitions is thus essential for assessing the suitability of new materials for light-emitting devices.

Quantum Chemical Insights into DNA Nucleobase Oxidation: Bridging Theory and Experiment.

The oxidation free energies of DNA nucleobases in aqueous solution are still matter of extensive discussion because of the contrasting results reported so far. With the aim of settling a longstanding debate about the oxidation potentials of DNA constituents, herein we report the results of state-of-the-art DFT-based molecular dynamics simulations, in which the whole solvent environment is modeled at the atomistic level, by using DFT supercell calculations, with periodic boundary conditions. Calculated vertical ionization energies are very close to those observed by photoelectron spectroscopy both in the gas phase and in solution.

IPLOT-VKA: An Integral-Method Powell-pLOT-Enhanced Visual Kinetic Analysis for the Determination of Orders of Reaction.

Determination of partial orders of reactions in kinetics is a general entry step for any mechanistic investigation; recently, considerable attention has been given to the benefits of using visual methods to help in this task, such as easy utilization and data-efficiency. In this respect, we here revisit and improve the classic method by Powell and Margerison for kinetic analysis. For the first time, analytical equations for a bimolecular reaction have been worked out for all values of partial orders of reactions, and the solutions have been implemented in a free, open-access and easy-to-use Web-application, named IPLOT-VKA, which also allows estimation of the errors on the kinetic constant, and residual standard error on concentrations.

The dynamic nature of electrostatic disorder in organic mixed ionic and electronic conductors.

Charge dynamics in disordered media is described invariably assuming that the energy landscape for hopping site energy is stationary. Within the same framework, the correlation between low electronic disorder and high charge mobility is considered extremely robust, despite the emergence of materials with mixed ionic and electronic conductivity (OMIECs) that display high mobility coexisting with large disorder. We show in this work that the disorder of OMIEC polymers is highly dynamical, the on-site energy for charge transport fluctuates with a characteristic time comparable with that of electron transport.

Asymmetrical Diketopyrrolopyrrole Derivatives with Improved Solubility and Balanced Charge Transport Properties.

The diketopyrrolopyrrole (DPP) unit represents one of the building blocks more widely employed in the field of organic electronics; in most of the reported DPP-based small molecules, this unit represents the electron acceptor core symmetrically coupled to donor moieties, and the solubility is guaranteed by functionalizing lactamic nitrogens with long and branched alkyl tails. In this paper, we explored the possibility of modulating the solubility by realizing asymmetric DPP derivatives, where the molecular structure is extended in just one direction. Four novel derivatives have been prepared, characterized by a common dithyenil-DPP fragment and functionalized on one side by a thiophene unit linked to different auxiliary electron acceptor groups.

Electron Localization and Mobility in Monolayer Fullerene Networks.

The novel 2D quasi-hexagonal phase of covalently bonded fullerene molecules (qHP C), the so-called graphullerene, has displayed far superior electron mobilities, if compared to the parent van der Waals three-dimensional crystal (vdW C). Herein, we present a comparative study of the electronic properties of vdW and qHP C using state-of-the-art electronic-structure calculations and a full quantum-mechanical treatment of electron transfer. We show that both materials entail polaronic localization of electrons with similar binding energies (≈0.

The rates of non-adiabatic processes in large molecular systems: Toward an effective full-dimensional quantum mechanical approach.

Two computational approaches for computing the rates of internal conversions in molecular systems where a large set of nuclear degrees of freedom plays a role are discussed and compared. One approach is based on the numerical solution of the time-dependent Schrödinger equation and allows us to include almost the whole set of vibrational coordinates, thanks to the employment of effective procedures for selecting those elements of the Hilbert space which play a significant role in dynamics. The other approach, based on the time-dependent perturbation theory and limited to the use of the harmonic approximation, allows us to include the whole Hilbert space spanned by the vibrational states of the system.

Formation of electron traps in semiconducting polymers via a slow triple-encounter between trap precursor particles.

Already in 2012, Blom et al. reported (Nature Materials 2012, , 882) in semiconducting polymers on a general electron-trap density of ≈3 × 10 cm, centered at an energy of ≈3.6 eV below vacuum.

Cervical Spondylotic Myelopathy: From the World Federation of Neurosurgical Societies (WFNS) to the Italian Neurosurgical Society (SINch) Recommendations.

Cervical spondylotic myelopathy (CSM) is a progressively growing pathology to afford by a spinal surgeon due to the aging of the population, associated with better treatment management and the best diagnosis and treatment solutions are greatly discussed. Nowadays that scientific literature is progressively increasing to identify the gold standard in diagnosis and treatment can be very challenging. This is particularly evident in spinal surgery with many different indications not only in different countries but also in the same local reality.

Simulation of polymeric mixed ionic and electronic conductors with a combined classical and quantum mechanical model.

In organic polymeric materials with mixed ionic and electronic conduction (OMIEC), the excess charge in doped polymers is very mobile and the dynamics of the polymer chain cannot be accurately described with a model including only fixed point charges. Ions and polymer are comparatively slower and a methodology to capture the correlated motions of excess charge and ions is currently unavailable. Considering a prototypical interface encountered in this type of materials, we constructed a scheme based on the combination of MD and QM/MM to evaluate the classical dynamics of polymer, water and ions, while allowing the excess charge of the polymer chains to rearrange following the external electrostatic potential.

[The nurses' strike in the United Kingdom: the reasons, the debate and the implications].

Unlabelled: . The nurses' strike in the United Kingdom: an overview of the reasons, debate and implications.

Introduction: In the UK, where the National Health Service (NHS) was founded, one of the most important and long-lasting strikes in nursing is taking place.

Charge Localization in Acene Crystals from Electronic Structure.

The performance of Koopmans-compliant hybrid functionals in reproducing the electronic structure of organic crystals is tested for a series of acene crystals. The calculated band gaps are found to be consistent with those achieved with the method at a fraction of the computational cost and in excellent accord with the experimental results at room temperature, when including the thermal renormalization. The energetics of excess holes and electrons reveals a struggle between polaronic localization and band-like delocalization.

Sol-Gel Dipping Devices for HS Visualization.

In this contribution we report the synthesis and full characterization, via a combination of different spectroscopies (e.g., H NMR, UV-vis, fluorescence, MALDI), of a new family of fluorescent zinc complexes with extended π-conjugated systems, with the final aim of setting up higher performance HS sensing devices.

Salen, salan and salalen zinc(II) complexes in the interaction with HS: time-resolved fluorescence applications.

In the current work we investigate the route of interaction of a newly synthesized family of zinc complexes with HS by a plethora of different spectroscopic techniques. A computational analysis on the time dependent density functional theory (TD-DFT) level explored the overall fluorescence properties of the title complexes and their different fluorescence responses to HS. Time-resolved fluorescence experiments were also performed and highlight the great potential of the current systems to be implemented as HS fluorescent sensors.

Is a thin mechanism appropriate for aromatic nitration?

The mechanism of toluene nitration by NOBF in dichloromethane solution is investigated by performing advanced MD simulations of the reaction trajectories, including at full quantum mechanical level the effects of both the solvent and of the counterion. The time evolution of the encounter complex, as well as that of the associated electronic structure, for different trajectories reveals that a single electron transfer step fastly occurs after reactants are accommodated in a common solvation shell, always preceding the formation of the σ-complex. The present results strongly suggest that the regioselectivity of the reaction is spin-density driven and that a thin mechanism, one based on reaction intermediates and transition states, can be appropriate to describe aromatic nitration.

Duplex DNA Retains the Conformational Features of Single Strands: Perspectives from MD Simulations and Quantum Chemical Computations.

Molecular dynamics simulations and geometry optimizations carried out at the quantum level as well as by quantum mechanical/molecular mechanics methods predict that short, single-stranded DNA oligonucleotides adopt conformations very similar to those observed in crystallographic double-stranded B-DNA, with rise coordinates close to ≈3.3 Å. In agreement with the experimental evidence, the computational results show that DNA single strands rich in adjacent purine nucleobases assume more regular arrangements than poly-thymine.

On the JAP Method for the Indirect Determination of Delocalized Currents from Experimental Chemical Shifts.

The JAP model (after Jirásek, Anderson, and Peeks) to retrieve global current strengths from experimental H chemical shifts has been tested with DFT computations. Both global and local tropicities are correctly predicted in most cases and the quantitative agreement is overall fair. An extension of the model is found to give improvement in an exemplary critical case, where the global delocalized current is negligible and the current density map is dominated by local currents.

Paper-Strip-Based Sensors for HS Detection: A Proof-of-Principle Study.

In this work, the authors explored the interaction of a suite of fluorescent zinc complexes with HS. The authors provide evidence that HS binds the zinc center of all the complexes under investigation, allowing them to possibly function as sensors by a 'coordinative-based' approach. Naked-eye color changes occur when treating the systems with HS, so the fluorescence responses are modulated by the presence of HS, which has been related to a change in the energy level and coupling of excited states through a computational study.

High-Energy-Density Materials: An Amphoteric N-Rich Bis(triazole) and Salts of Its Cationic and Anionic Species.

The synthesis and characterization of the N-rich bis(triazole) compound 1,4'-[3,3'-bis(1,2,4-triazole)]-4',5,5'-triamine (CHN) with a N content of 69.6% by weight is reported. The compound exhibits a rich acid-base behavior because it can accept up to two protons, forming a monocation and a dication, and can lose one proton, forming an anion.

The Time Scale of Electronic Resonance in Oxidized DNA as Modulated by Solvent Response: An MD/QM-MM Study.

The time needed to establish electronic resonant conditions for charge transfer in oxidized DNA has been evaluated by molecular dynamics simulations followed by QM/MM computations which include counterions and a realistic solvation shell. The solvent response is predicted to take 800-1000 ps to bring two guanine sites into resonance, a range of values in reasonable agreement with the estimate previously obtained by a kinetic model able to correctly reproduce the observed yield ratios of oxidative damage for several sequences of oxidized DNA.

Quantitative Prediction of the Electro-Mechanical Response in Organic Crystals.

Organic semiconductors' inherent flexibility makes them appealing for advanced applications such as wearable electronics, e-skins, or pressure sensors, and can even be used to enhance their intrinsic electronic properties. Unfortunately, these applications for organic materials are currently hindered by the lack of a quantitative understanding of the interplay between their electrical and mechanical properties. In this work, this gap is filled by presenting an accurate methodology able to predict quantitatively the effects of external deformation on the charge transport properties of any organic semiconductors.

Outcome Features Analysis in Intramedullary Tumors of the Cervicomedullary Junction: A Surgical Series.

Object:  The aim of this study is to investigate the impact of surgery for different cervicomedullary lesions on symptomatic pattern expression and postoperative outcome. We focused on specific outcome features of the early and late postoperative assessments. The former relies on surgery-related transient and permanent morbidity and feasibility of radicality in eloquent areas, whereas the latter on long-term course in lower grade tumors and benign tumorlike lesions (cavernomas, etc.

Reliable Predictions of Benzophenone Singlet-Triplet Transition Rates: A Second-Order Cumulant Approach.

Fermi golden rule and second-order cumulant expansion of the time-dependent density matrix have been used to compute from first principles the rate of intersystem crossing in benzophenone, using minimum-energy geometries and normal modes of vibrations computed at the TDDFT/CAM-B3LYP level. Both approaches yield reliable values of the S decay rate, the latter being almost in quantitative agreement with the results of time-dependent spectroscopic measurements (0.154 ps observed vs 0.

Efficacy of Daptomycin-Containing Regimen for Treatment of Staphylococcal or Enterococcal Vertebral Osteomyelitis: A Prospective Clinical Experience.

Vertebral osteomyelitis (VO) is a compelling clinical entity for clinicians, because of its insidious and indolent course that makes diagnosis difficult. A concern is reported about the choice of antibiotic regimens, duration of therapy, and criteria to switch to oral therapy. We conducted a prospective observational study.