402 research outputs found

    Correction: automated assessment of redox potentials for dyes in dye-sensitized photoelectrochemical cells

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    Correction for 'Automated assessment of redox potentials for dyes in dye-sensitized photoelectrochemical cells' by Jelena Belić et al., Phys. Chem. Chem. Phys., 2022, 24, 197-210, https://doi.org/10.1039/D1CP04218A.NWO733.000.007Solid state NMR/Biophysical Organic Chemistr

    Automated assessment of redox potentials for dyes in dye-sensitized photoelectrochemical cells

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    NWO733.000.007Solid state NMR/Biophysical Organic Chemistr

    Systematic Computational Design and Optimization of Light Absorbing Dyes

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    We present a workflow to aid the discovery of new dyes for the role of a photosensitive unit in the dye-sensitized photo-electrochemical cells (DS-PECs). New structures are generated in a fully automated way using the Compound Attachment Tool (CAT) introduced in this work. These structures are characterized with efficient approximate density functional theory (DFT) methods, and molecules with favorable optical properties are suggested for possible further use in DS-PECs. As around 2500 structures are generated in this work, and as we aim for still larger volumes of compounds to screen in subsequent applications, we have assessed the reliability of low-cost screening methods and show that simplified time-dependent density functional theory (sTDDFT) provides a satisfying accuracy/cost ratio. From the dyes considered, we propose a set that can be suitable for panchromatic sensitization of the photoelectrode in DS-PECs to further increase DS-PEC efficiency.Solid state NMR/Biophysical Organic Chemistr

    Coupled Dipole Method Determination of the Electromagnetic Force on a Particle over a Flat Dielectric Substrate

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    We present a theory to compute the force due to light upon a particle on a dielectric plane by the Coupled Dipole Method (CDM). We show that, with this procedure, two equivalent ways of analysis are possible, both based on Maxwell's stress tensor. The interest in using this method is that the nature and size or shape of the object, can be arbitrary. Even more, the presence of a substrate can be incorporated. To validate our theory, we present an analytical expression of the force due to the light acting on a particle either in presence, or not, of a surface. The plane wave illuminating the sphere can be either propagating or evanescent. Both two and three dimensional calculations are studied.Comment: 10 pages, 8 figures and 3 table

    Allowed Gamow-Teller Excitations from the Ground State of 14N

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    Motivated by the proposed experiment 14N(d,2He)14C^{14}N(d,{^2He})^{14}C, we study the final states which can be reached via the allowed Gamow-Teller mechanism. Much emphasis has been given in the past to the fact that the transition matrix element from the JĎ€=1+T=0J^{\pi}=1^+ T=0 ground state of 14N^{14}N to the JĎ€=0+T=1J^{\pi}=0^+ T=1 ground state of 14C^{14}C is very close to zero, despite the fact that all the quantum numbers are right for an allowed transition. We discuss this problem, but, in particular, focus on the excitations to final states with angular momenta 1+1^+ and 2+2^+. We note that the summed strength to the JĎ€=2+T=1J^{\pi}=2^+ T=1 states, calculated with a wide variety of interactions, is significantly larger than that to the JĎ€=1+T=1J^{\pi}=1^+ T=1 final states.Comment: Submitted to Phys. Rev.

    In silico optimization of charge separating dyes for solar energy conversion

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    Dye-Sensitized Photoelectrochemical Cells are promising devices in solar energy conversion. However, several limitations still have to be addressed, such as the major loss pathway through charge recombination at the dye-semiconductor interface. Charge separating dyes constructed as push-pull systems can increase the spatial separation of electron and hole, decreasing the recombination rate. Here, we in silico investigate a family of dyes, consisting of polyphenylamine donors, fluorene bridges and perylene monoimide acceptors using a combination of semi-empirical nuclear dynamics and a quantum propagation of photoexcited electron and hole. To optimize the charge separation, several molecular design strategies are investigated, including modifying the donor molecule, increasing the π-bridge length and decoupling the molecular components through steric effects. It is found that the combination of a triphenylamine donor, using an extended 2-fluorene π-bridge and decoupling the different components by steric hindrance from side groups results in a dye with significantly improved charge separation properties in comparison to the original supramolecular complex.NWO733.000.007Solid state NMR/Biophysical Organic Chemistr

    Geometric origin of mechanical properties of granular materials

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    Some remarkable generic properties, related to isostaticity and potential energy minimization, of equilibrium configurations of assemblies of rigid, frictionless grains are studied. Isostaticity -the uniqueness of the forces, once the list of contacts is known- is established in a quite general context, and the important distinction between isostatic problems under given external loads and isostatic (rigid) structures is presented. Complete rigidity is only guaranteed, on stability grounds, in the case of spherical cohesionless grains. Otherwise, the network of contacts might deform elastically in response to load increments, even though grains are rigid. This sets an uuper bound on the contact coordination number. The approximation of small displacements (ASD) allows to draw analogies with other model systems studied in statistical mechanics, such as minimum paths on a lattice. It also entails the uniqueness of the equilibrium state (the list of contacts itself is geometrically determined) for cohesionless grains, and thus the absence of plastic dissipation. Plasticity and hysteresis are due to the lack of such uniqueness and may stem, apart from intergranular friction, from small, but finite, rearrangements, in which the system jumps between two distinct potential energy minima, or from bounded tensile contact forces. The response to load increments is discussed. On the basis of past numerical studies, we argue that, if the ASD is valid, the macroscopic displacement field is the solution to an elliptic boundary value problem (akin to the Stokes problem).Comment: RevTex, 40 pages, 26 figures. Close to published paper. Misprints and minor errors correcte

    Honeybees balance essential fatty acids and suffer cognitively from deficiency

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    Abstract Background and aims. Epidemiological data on autoimmune hepatitis (AIH) are scarce. In this study, we determined the clinical and epidemiological characteristics of AIH patients in the Netherlands (16.7 million inhabitants). Methods. Clinical characteristics were collected from 1313 AIH patients (78% females) from 31 centers, including all eight academic centers in the Netherlands. Additional data on ethnicity, family history and symptoms were obtained by the use of a questionnaire. Results. The prevalence of AIH was 18.3 (95% confidential interval [CI]: 17.3-19.4) per 100,000 with an annual incidence of 1.1 (95% CI: 0.5-2) in adults. An incidence peak was found in middle-aged women. At diagnosis, 56% of patients had fibrosis and 12% cirrhosis in liver biopsy. Overall, 1% of patients developed HCC and 3% of patients underwent liver transplantation. Overlap with primary biliary cirrhosis and primary sclerosing cholangitis was found in 9% and 6%, respectively. The clinical course did not differ between Caucasian and non-Caucasian patients. Other autoimmune diseases were found in 26% of patients. Half of the patients reported persistent AIH-related symptoms despite treatment with a median treatment period of 8 years (range 1-44 years). Familial occurrence was reported in three cases. Conclusion. This is the largest epidemiological study of AIH in a geographically defined region and demonstrates that the prevalence of AIH in the Netherlands is uncommon. Although familial occurrence of AIH is extremely rare, our twin data may point towards a genetic predisposition. The high percentage of patients with cirrhosis or fibrosis at diagnosis urges the need of more awareness for AIH
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