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In this theoretical work, density functional theory calculations show the effect of small cobalt clusters (Con, n = 1–5) adsorbed on pristine γ‐graphyne (γ‐GY), and modify N‐doped γ‐GY monolayers (GYNs‐def). Different geometrical configurations are assessed with the adsorption energy, charge transfer, and density of states. The system with vacancy defects shows a large adsorption energy (19.96 eV) for the Co5 cluster. This behavior may be associated to the overlapping of the electronic state contributions between cobalt and carbon atoms in the valence states. This indicates that the Co5 cluster could be deposited on N‐doped γ‐GY monolayers (Con@GYNs‐def). The lowest‐energy systems are evaluated to estimate the strength of the interaction with hydrogen molecules (xH2, where x = 1–5). According to the adsorption energy values, the modified γ‐GY monolayers are allowed to be a suitable support material to capture H2 molecules via the small Con clusters. The hydrogen retention capacity for the supported cobalt atoms corresponding to the lowest‐energy configurations and larger systems are evaluated by using molecular dynamics simulations with the Born–Oppenheimer approximation. The role played by defects in the GYNs‐def monolayers is important, since the Con clusters remain attached to the vacancy with the absence of surface diffusion. This study may represent a guide to tailor novel nanostructures based on small cobalt clusters supported on graphyne monolayers modified to be applied in H2 adsorption. [ABSTRACT FROM AUTHOR]

Abstract Electrode materials for energy storage devices based on carbon materials have shown to be a reliable choice in supercapacitors or Li-ion batteries. The development of novel carbon materials may improve the performance of such devices and the use of eco-friendly materials from biomass waste may provide a breakthrough in the area. In this study, we give theoretical insights into the in silico design of carbon materials based on lignocellulosic molecules present in the waste residues. We performed pyrolysis-simulated calculations at the ReaxFF level with the Adler's softwood lignin model as the precursor material. Different models were implemented by randomly combining massive lignocellulosic molecules. The simulated pyrolysis of the lignocellulosic components was performed starting with a heating step from room temperature to a temperature limit of 1280 K, followed by a stabilization period. The reaction was subjected to quenching, and finally to a period of thermal equilibrium. The formed char was characterized as nanoporous carbon according to its density, radial distribution function and pore size distributions. Comparison of these results with our available experimental data revealed reasonable agreement. This may aid in the design of carbon electrodes for energy storage devices and applications in which stable and predictable properties are desirable. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract In this theoretical work, we present the results from Density Functional Theory (DFT) calculations on novel systems formed by graphyne-γ (GY-γ) with defects, and Nitrogen-doped graphyne (GYN) systems. Systems with vacancy defects present a widening on the band gap. We found that the electronic properties of the GYN family may be tuned, from a semiconducting to a metallic character. This may be due to the presence of Nitrogen atoms (N) in acetylenic linkages. The N-doping was shown to generate thermodynamically stable systems with different electronic properties, which can be further confirmed by ab initio Molecular Dynamics simulations. In this work, we also analyzed the chemical stability and reactivity with the following criteria: hardness, chemical potential, and electronic density. The GYN system with defects (GYN-def) presents the lowest-energy of formation and cohesion, indicating that it may correspond to the most energetically stable system. The catalytic character of the series of graphyne systems under study was tested by assessing the capability to adsorb the O 2 molecule on the graphyne substrate. It was discovered that the GYN-β and -δ systems represent models able to achieve O 2 molecular chemisorption onto the surface, due to the modified electronic structure after N-doping. We found activation barriers below 0.70 eV. This addresses that the process might occur spontaneously at rom temperature. Such graphyne systems represent potential candidates to be implemented as catalysis in devices such as fuel cell cathode materials. [ABSTRACT FROM AUTHOR]

Carbon has shown to give excellent performance in electrodes of energy storage devices, such as Li-ion batteries and supercapacitors. The grafting of polyoxometalates (POM) at carbon has scarcely been explored at the theoretical and experimental level, and the mechanism behind the chemical bonding between POM and carbon has not been fully understood. In order to give insights into these issues, an electronic structure study was carried out on the following POM systems adsorbed on carbon: PdMo, RuNb, SiMo, PMo and SiW. The prediction of the existence and chemical stability of PdMo and RuNb systems is reported for the first time. All systems were fully optimized with the nominal charges and also neutralized with counterions, as a benchmark to elucidate an optimal scheme that models the interaction in these nanocomposite systems. The POM/carbon attraction lies at about 250 pm in average, which may be addressed to a non-covalent bonding of the electrostatic-type, where the van der Waals contribution may also play a role. The density of states is evidently increased around the Fermi level in all POM/carbon systems. This may be due to the rising of new trajectories that ions may follow at the electrode of a solid-state device, such as a supercapacitor, giving as a result the strengthening of density current values and pseudocapacitive properties than those observed in pristine carbon systems. It was found that the SiWO and RuNb POM systems may be more feasible to be adsorbed on carbon substrates and may not require functional groups to allow POM retention. These systems represent potential candidates to be considered in nanohybrid electrodes for solid-state applications. [ABSTRACT FROM AUTHOR]

This DFT study examined the interaction of a sulfated zirconia (SZ) slab model system (heterogeneous catalyst) and triacetin (a precursor in biodiesel production) using explicit methanol solvent molecules. Full geometry optimizations of the systems were performed at the B3LYP level of theory. Gibbs free energies provide insight into the spontaneity of the reactions along a three-step reaction mechanism for the transesterification of triacetin. Charge decomposition analysis revealed electronic charge transfer between the metallic oxide and the organic moieties involved in the reaction mechanism. Fukui indices indicate the likely locations on the SZ surface where catalysis may occur. The quadratic synchronous transit scheme was used to locate transition structures for each step of the transesterification process. The results are in agreement with the strongly acidic catalytic character of zirconium observed experimentally in the production of biodiesel. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Core@shell nanohybrids as MWCNT@TiO 2 are a reliable alternative in the use of electrode materials for Li-ion batteries, since the specific capacity is enhanced as compared to pristine MWCNT and TiO 2 . Shell thickness and the degree of disorder appear to play an important role in such behavior at the graphene interface/oxide. We performed molecular dynamics and DFT calculations to understand the nature of bonding at the nanohybrid interface and the degree of disorder caused by the bonding of the oxide on the graphene surface. Growing of shell thickness with increasing number of TiO 2 nanoparticles was simulated using a reactive force field, and an optimum configuration was found. Shell size plays a dominant role in the rising of enhanced electronic states around the Fermi level, increasing chemical capacity. Interestingly, at the optimum shell thickness, stability of the MWCNT is not compromised and the value of the density of states at the Fermi level is the largest. This provides the structural features to improve the design of core@shell materials for Li-ion batteries. It may be of particular relevance to synthesize composites based on MWCNT to improve performance of several materials for Li-ion storage, since the same trend can be expected to other systems. [ABSTRACT FROM AUTHOR]

Keggin polyoxometalate structures are molecular clusters that, anchored to carbon matrices, have been used to form electrodes for energy storage devices, such as lithium batteries and supercapacitors. [ PMo 12 O 40 ] 3 - polyanions (PMo12) are examples of this kind of nanostructures that, grafted on amorphous carbon, have the capability to enhance the capacitive properties of these electrochemical ensembles. However, there is yet a poor understanding of the fundamental mechanisms for bond formation between them and carbon structures. It has been found experimentally that the presence of functional groups such as φ-NH2 and φ-OH assists on the chemical absorption of PMo12, but there is not enough information on the actual mechanism of the process. In order to gather further knowledge on these issues, we have performed quantum mechanical calculations, based on the density functional theory of atomic arrangements using graphene as carbon structure model, different functional groups, and PMo12. Our aim was to look for the nature of bonding among them, and to dig into the charge properties to relate them with the experimental observation. From the computations performed with PMo12 polyanion near to a graphene sheet, with and without the presence of functional groups, we conclude that there is a non-covalent/electrostatic bonding, made of weak π – π stacking interactions between PMo12 and graphene. Calculations show that φ-NH2 and φ-OH functional groups are able to form covalent bonds with PMo12 in top and side fashion arrangements, being the latter the most stable. This is a powerful argument to explain the empirical observation on these groups, enhancing the PMo12 adsorption over carbon structures. We also found that the presence of the functional groups together with PMo12 creates electronic states that may act as alternative pathways that ions can track within electrochemical cells. Our results offer first-principle information relevant to the understanding of these composite materials, and the methodology could be directly applied to other Keggin structures or different functional groups, attached to graphene, to find potential advantages for energy storage devices. [ABSTRACT FROM AUTHOR]

The prediction of the series of [AuXM] compounds (with X = H, F, Cl, Br, I and M = Li, Na, K, Rb, Cs) has been carried out by ab initio and DFT calculations. The systems are chemically stable due to their high chemical hardness. An unusual Au-Au attraction was found on each of the compounds along the series, addressing a strong metalophilic interaction of the aurophilic type. A strong aromatic character on the center of the [AuX] ring was also detected in the compounds under study, enhancing the stability of the species. The mechanism behind the bonding of the systems is mainly ruled by an electrostatic interaction among the 2 M cations and the [AuX] monolayer sheet in accordance with CDA and Ziegler analysis; only a slight orbital contribution yielded by back-donation from the alkaline metals to the [AuX] monolayer sheet is involved. It was shown that the [AuClM] group has the highest Fukui indexes, indicating that a catalytic reaction may rise from an electrophilic attack centered at the Au atoms or a nucleophilic attack on the alkaline-earth metals. The latter was tested with the most stable system of this group, namely [AuClLi], allowing it to interact with a CO molecule; the optimized [AuClLi] [CO] system represents a bound state that highlights the reactive properties of the species. An extended ...-M-S-M-S-M-... (with S representing the [AuX] system) linear chain model was also predicted at DFT level. Considering its spatial representation of the frontier molecular orbitals, it was found that a possible electronic transfer along the chain may take place via the triggering of an electron, suggesting the existence of a nanowire. [ABSTRACT FROM AUTHOR]

An ab initio, systematic study on the aromaticity involving the group of metalated extended porphyrins, termed meso-hexakis(pentafluorophenyl)-substituted[26]hexaphyrin(1.1.1.1.1.1) (HP), was performed for the first time. The aromatic behavior of the system shifted to antiaromatic in the [28]HP analogue, due to the presence of hydrogen atoms that break the orbital symmetry. The absorption bands observed in the experiment were assigned to an intraligand charge transfer, where the intrametallic character is also important. The excited states reveal the absorption of visible light and the possibility of electronic transfer to different systems. We propose a system such as single-walled carbon nanohorns (SWCNHs), due to their special electronic properties, and predict a novel nanohybrid material. The evidence of electronic communication between both species is presented in this work. The HP aromaticity and the spatial configuration of the interaction with SWCNHs are also related to the strength of electronic transfer among the systems, making the HP metalated antiaromatic species and their corresponding nanohybrids potential candidates to be used as building blocks in photovoltaic cell materials. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The Au(I)-Au(I) closed-shell or aurophilic attraction has been the subject of interest in the experimental and theoretical chemistry fields, due to the intriguing properties associated to it. The presence of phosphorescence in 'aurophilic' compounds has been addressed to a wide range of applications, but it has not yet been fully understood. A theoretical study on the electronic and phosphorescent properties of the following series of dinuclear gold complexes has been performed: [Au2(dmpm) (i-mnt)] ( 1), [Au2(μ-Me-TU) (μ-dppm)] ( 2), and [Au2(μ-G)(μ-dmpe)] ( 3). Full geometry optimizations at the second-order Møller-Plesset perturbation theory (MP2) were carried out for each of the species. These calculations made evident that, at the ground-state geometry, the Au(I) cations allocated at the center of the ring show a short Au-Au distance below the sum of the van der Waals radii, at the range of the aurophilic attraction. An intermolecular Au(I)-Au(I) closed-shell attraction for a pair of the systems under study is found. This attraction is comparable to that of the hydrogen bonds. The phosphorescent properties experimentally observed for this series were also characterized through ab initio techniques. The obtained results allow to fit reasonably the excitation energies with the experimental data and to identify a correlation between the strength of the Au(I)-Au(I) interaction and the phosphorescent behavior. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

Abstract: Parasitism in skeletal muscles and myositis are commonly observed during experimental Trypanosoma cruzi infection. The effect of T. cruzi infection on contractile properties of skeletal muscles in consecutive periods of the acute infection in BALB/c mice was studied. Albarrada strain (clone 4) which was isolated in Mexico and has demonstrated a high level of blood parasitemia and parasitism in skeletal muscles was used. Isolated strips of rectus abdominis muscle were subjected to direct electrical field in vitro. Alternatively, plantaris muscles were stimulated in situ through the sciatic nerve. The peak amplitudes of a single twitch and tetanus contractions were considered to estimate the mechanical properties of muscles. Histopathological analysis was performed to correlate functional changes with the evolution of tissue parasitism and tissue injury. Contractile properties of muscles were significantly attenuated during acute T. cruzi infection. The percentage of damaged muscles rather than the character of tissue pathology affected their contractile properties significantly. [Copyright &y& Elsevier]

Abstract: The study of trimeric mixed-metal complexes is of great importance for their potential use in sensor devices and nanoparticle design, due to the fascinating luminescent and catalytic activity properties. The goal of this work is to understand the Au(I)–Ag(I) closed-shell metallophilic attraction and phosphorescent character in the representative Au–Ag complexes [Au2(carb)2Ag(μ-3,5-Ph2pz)] (1) and [Au(im)CH3(pz)Ag2(μ-3,5-H2pz)2] (2) through ab initio and DFT techniques. The metal–metal intramolecular interactions are ruled by a Au 5d and Ag 4d mixing, while the intermolecular attractions are governed by a Au 6s and Ag 5s mixing, by π-stacking attractions coming from pz groups and dispersion interactions in complex 2. The phosphorescence reported experimentally may be addressed to MLCT transitions, with intrametallic contributions, where a distortion of the lowest-energy excited state geometry of the monomer and dimer are also involved. [Copyright &y& Elsevier]

The complex [AuS2PPh(OCH2CH=CH2)]2 (1) presents an Au(I)–Au(I) intramolecular and intermolecular bonding with luminescence properties. To understand the nature of these features, fully optimized geometries were obtained by three computational methods, DFT/B3LYP, MPW1B95 and MP2. An Au(I)–Au(I) intramolecular bond was found in the ground state, at the three levels of theory, exhibiting an aurophilic interaction between the two gold atoms. Two molecules of the complex were optimized using DFT/B3LYP, in order to analyze the intermolecular interaction between them. The resulting intermolecular bonding distance between the two adjacent gold atoms on each molecule is 3.16 Å, indicating a strong aurophilic attraction. Time dependent calculations indicate that the first excited state with nonzero oscillator strength is a singlet, with an excitation energy equal to 3.16 eV. This should correspond to the absorption band seen experimentally at 3.10 eV. The lowest energy emission of (1) was obtained at 2.73 eV, which corresponds to the emission peak resulting from phosphorescence and located at 2.53 eV. This transition comes from an excited electron on the p orbitals of the ligands that is transferred to the d orbitals of the gold atoms on the HOMO. This interaction may be attributed to Ligand to Ligand–Metal Charge Transfer (LL–MCT). [Copyright &y& Elsevier]

The vacuole, occupying up to 95% of the volume of a mature higher plant cell, serves as a main store of solutes and as the key element of intracellular Ca2+- and pH-stat. The role of the vacuole in the ionic homeostasis of the cell is also evident under K+-starving conditions and under salt stress. It is involved in the regulation of turgor and cell volume, and in specialized cells, such as stomatal guard cells, a large central vacuole is a principle component of the cell osmotic motor. For more than a decade, the guard cell has gained the status of a higher plant cell model, intensely studied by physiological, cell and molecular biology techniques. Despite tremendous progress in the understanding of signal transduction events taking place at plasma membrane of guard cells, the involvement of vacuolar ion transporters remains a significant challenge. Like in a plasma membrane, the ionic transport across the vacuolar membrane, the tonoplast, is directed and coordinated through a complex set of specific transport proteins, including pumps, transporters, and ionic channels. During recent years, the application of modern electrophysiological techniques (principally, the patch-clamp) has enabled numerous individual ion channels to be functionally characterized, although none of them has been structurally identified. The work of our group is focused on the characterization of so called slow (SV) and fast (FV) vacuolar ion channels, which have a wide, if not ubiquitous, distribution in higher plants, and can be detected in stems, leaves, as well as in root storage tissue. Their ionic selectivity, gating by membrane voltage and by physiologically abundant cations, as well as their possible roles in signal transduction and ionic balance are discussed. [ABSTRACT FROM AUTHOR]

The task of creating a remarkably stable and effective electrochemical catalyst for efficient hydrogen evolution is arduous, primarily due to the multitude of factors that need to be taken into account for the industrial utilization of Pt. In this work, hybrid formation through in - s i t u reduction of Pt onto biogenic porous silica (Pt-SiO 2) is tested for its use as an efficient catalyst for hydrogen production. Exceptionally high electrocatalytic activity and excellent reusability of catalysts up to 200 cycles have been demonstrated. Pt-SiO 2 with low Pt content of 0.48 to 0.82 at% with active catalytic sites exhibit superior catalytic activity with a Tafel slope of 22 mV dec−1 and an overpotential of 28 mV (vs. RHE at 10 mA cm−2) as compared to the Pt wire and previously reported bare Pt-SiO 2 (0.65 at% and 0.48 at% of Pt), and hybrid (Pt/Ag) structures formed onto two different biogenic porous SiO 2 substrates. The best catalytic performance of the Pt 1 Ag 3 cluster, representing a low Pt concentration, has been validated by Density Functional Theory (DFT) calculations. Here, the high production from the Pt 1 Ag 3 cluster is assigned to the mutual synergistic effect between Pt/Ag atoms. The Pt atoms transfer the excess charge to the nearest Ag neighbors inside the cluster, facilitating hydrogen diffusion on the activated sites. These important findings authenticate the superior hydrogen production at reduced Pt concentration on amine-functionalized biogenic porous silica.   [ABSTRACT FROM AUTHOR]

Doped fullerenes are extraordinary materials with unique electronic and optical properties, which also show potential for diverse biomedical applications. Employing density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) calculations; we studied the propensity of C36 and C35E (E=N and B) fullerenes as potential nanovehicles for certain neuroprotective drugs that are efficacious for Parkinson's disease. Baclofen, modafinil, rasagiline and rivastigmine were systematically studied to analyze whether they could be carried by small fullerenes. C36 and C35N fullerenes represent promising nanostructure candidates, due to their adsorption energy (physisorption) and favorable electrostatic interaction for the molecular transport of baclofen and rivastigmine drugs. Furthermore, in order to evaluate the effect of temperature on these interactions, ab initio molecular dynamics (AIMD) were also performed. The results from this work are expected to motivate additional investigations concerning these systems, using both theoretical and experimental approaches, in order to demonstrate their versatility as novel carbon‐based nanovehicles. [ABSTRACT FROM AUTHOR]

Pristine and boron‐doped fullerenes have been widely investigated for their possible use in medical applications, as drug delivery nanovehicles. In this study, we investigate bare and B‐doped C20, C36 and C60 fullerenes and their interaction with piribedil drug molecule, based on density functional theory (DFT). Calculations were performed using the functional PBE of general gradient approximation, empirical dispersion correction by Grimme under vacuum conditions, pentylethanoate and water media. In this article, we examine optimized geometries, binding energies, theoretical IR spectra and the plots of Molecular Electrostatic Potential, as well as HOMO and LUMO orbitals, density of states (DOS) and the quantum theory of atoms in molecules (QTAIM), in order to truly comprehend the interaction between various fullerenes and piribedil. Findings suggest that C36, C60 and C35B fullerenes might be used as drug delivery vehicles for piribedil because of their moderately high adsorption energies with piribedil. [ABSTRACT FROM AUTHOR]

With the aid of density functional theory (DFT) calculations, different models of porous carbon monolayers were proposed for the development of anode materials for lithium-ion batteries (LIB). Special attention was given to the pore size effect in the storage process and diffusion of Li ions. Porous carbon models were formed from the pristine graphene structure, by removing carbon atoms that mimic the pore formation. DFT calculations showed that the fundamental planar structure of graphene is preserved upon pore formation. The electronic structure properties of carbon are drastically altered with the enlargement of the pore size according to the introduced vacancies, allowing effective Li-ion adsorption in larger pores. Calculations based on atoms in molecules theory indicate that the Li ions interact with the pores via an electrostatic-type attraction, comparable to that of a hydrogen bonding. The porous carbon models exhibit the availability to retain a massive number of Li ions at the surface by keeping the original planarity of graphene. This is intimately related to an enhanced theoretical specific capacity that raises with increasing pore size. Such capacities are in close agreement with experimental data. Therefore, the formation of the pores improves Li ions diffusion compared to the pristine graphene. This is of special interest for the design of improved anode materials for Li ion batteries. This theoretical methodology can be applied as an auxiliary tool to tailor porous carbon materials intended to be used in Li ion batteries. [Display omitted] • The presence of porosity in carbon monolayers improves the Li+ ion diffusion. • Electronic delocalization in the porous carbon models enhanced Li+ ions adsorption. • The AIM analysis shows that the Li+ is easily adsorbed in the pore periphery. • Porous carbon is susceptible to adsorb larger number of Li+ ions on the surface. • Specific capacity and open circuit voltage are competitive with other anode materials. [ABSTRACT FROM AUTHOR]

Nanoporous carbon has been extensively used in a wide range of applications from water treatment to electrochemical applications, such as in energy storage devices. However, an attempt to relate structural and thermodynamical properties has not been explored from an atomistic approach. In this work we present a methodology to produce nanoporous carbon structures, using molecular dynamics simulations and a many-body potential. We designed a heating-quenching procedure in a thermodynamic region limited between the critical and triple point densities of carbon to study a sample of 1750 atomic arrangements produced at different densities, quench rates, and using graphite and diamond unit cells as precursor structures. All these samples were numerically characterized through the calculation of the free volumes, surface areas, radial distribution functions, and structure factors. We found particularly useful the potential energy dependence with s p 3 hybridization content, to compute structural phases through clustering methods. Three phases were found that comprise graphite-like, sponge-like, and unstable states. From our results we can conclude that our methodology, based on Tersoff potential, is compatible with available experimental data and different theoretical findings. In such case, our methodology is a reliable choice to produce nanoporous structures with low computational cost. [ABSTRACT FROM AUTHOR]

Photo-supercapacitors are combined devices that incorporate a photovoltaic cell as a light harvester unit to an electrical double layer capacitor where the charge carriers could be stored for further applications. Density functional theory calculations were performed to explore the electronic structure properties behind the mechanisms of electron communication between the interface of the solar cell material and the energy storage device. A hybrid perovskite was used to model the solar cell, while different carbon allotropes were considered as the molecular model of supercapacitor electrode. The communication of the perovskite with carbon is highly selective to the interaction of inorganic/organic termination and the carbon allotrope. Non-equilibrium Green's functions revealed the electron transmission behavior among the hybrid perovskite and the carbon allotropes, showing that the transport of charge carriers from the solar cell could be tuned with the adequate selection of the carbon allotrope. Quantum capacitance calculations were also performed to shed light into the intrinsic storage properties that the composite material may present. It shows that PbI and organic terminations in perovskite play a lead role to improve electronic charge retention, and consequently the inherent capacitance properties of the systems. This study also represents a combined theoretical/experimental work, in which an experimental methodology based on TEM graphics and XRD patterns allows to identify the inorganic/organic terminations in a hybrid perovskite solar cell material. This methodology could be implemented as a tool to tailor materials intended to improve the overall efficiency of a photo-supercapacitor device. • DFT calculations reveal the origin of electron transport at ETL interfaces. • Electron density between perovskite and carbon suggests sites for electron transport. • Perovskites with organic termination present low probability for electron transport. • Perovskites with inorganic PbI-termination induce charge carriers mobility at the ETL. • Simulated current-voltage profiles show a steady electron diffusion at the interface. [ABSTRACT FROM AUTHOR]

Cobalt-ceria catalysts (5 wt% in Co) were prepared using two different approaches: (i) a one-step synthesis through the EDTA-citrate complexing method, and (ii) via a traditional wet impregnation method. Materials were characterized by XRD, Raman, N2-adsorption, EDS, SEM, TEM, XPS, H2-TPR and O2-TPO. The catalytic properties in the methanol decomposition (MD) reaction were studied in a conventional flow reactor coupled to a GC, while in-situ DRIFTS studies followed the methanol surface reactivity. Moreover, DFT calculations on the methanol interaction with the Co/CeO2 system were performed to elucidate the mechanisms behind the MD. Catalytic tests showed that both cobalt-ceria catalysts exhibited excellent stability and significantly high hydrogen yields regardless of the synthesis procedure. Besides, during long-term operations (68 h on-stream), the impregnated sample (Co/CeO2-WI) exhibited an enhanced performance, attributed to the close interaction of cobalt species over the surface of the ceria support. In this regard, the DFT results showed that the Co dispersion on the ceria surface plays a dominant role in forming the methoxy group, exhibiting an evident selectivity to achieve the reaction. The DRIFTS study revealed an increased population of adsorbed carbonate species over the surface of the on-step catalyst (Co/CeO2-OS), probably blocking the active sites during long-term operations. [ABSTRACT FROM AUTHOR]

Manganese oxide (MnO 2) as an electrode material in energy storage devices has been used in supercapacitor electrodes because of its high capacitance and its sensitivity to the electrolyte chosen. In this work, density functional theory (DFT) calculations have been performed to understand the influence of the electrolyte MNO 3 with different metal cations (M =Li, Na, K) and the presence of water molecules on the α -MnO 2 surface. Through exploration of the potential energy surface, the relative energies involved in the diffusion process of M cations were described. The electronic density of states and the charge density differences allowed us to identify that the KNO 3 electrolyte improves charge accumulation in the α -MnO 2 structure. Quantum capacitance was calculated as an additional descriptor to elucidate the influence of the electronic structure properties on α -MnO 2 during the charging process. This theoretical modeling provides a comprehensive framework for understanding the mechanisms behind the ion charge transfer within the electrolyte. In particular, its interaction with the surface of the electrodes and the related pseudocapacitive properties. This work also provides insight into the charge/discharge processes of the electrode at the atomic level and may serve as a tool to tailor novel materials for energy storage devices. [Display omitted] • Manganese oxide offers high capacitance and sensitivity to chosen electrolytes. • DFT calculations show KNO 3 electrolyte enhances charge accumulation in α -MnO 2 structure. • Quantum capacitance suggests the electrolyte performance in α -MnO 2 as an electrode. • DFT provides insight into atomic-level charge/discharge processes in electrode α -MnO 2 [ABSTRACT FROM AUTHOR]

[Display omitted] • First experimental-theoretical study of CO oxidation on AuCu/TiO 2. • Enhanced stability of Au NPs due to migration of Cu species to the surface. • In-situ Raman highlights TiO 2 reducibility during the reaction. • DFT calculations confirmed the close interaction between metals and support. • Restructuration of the catalysts due to the CO interaction was unveiled. Bimetallic AuCu/TiO 2 catalysts were thoroughly studied during the CO oxidation reaction via three in-situ spectroscopic techniques (FTIR, UV–Vis and Raman) and density functional theory (DFT) calculations. Samples were synthesized through the deposition–precipitation with urea (DPU) method, and ex-situ characterized by several techniques. The superior catalytic activity displayed by the AuCu/TiO 2 sample was associated with the presence of nanoparticles in the form of heterodimers composed of the Au and Cu X O phases in close interaction with the TiO 2 support. In-situ DRIFTS results indicated that gold nanoparticles (NPs) presented some restructuration in the monometallic sample, while this event did not occur in the bimetallic one. The better stability on the AuCu/TiO 2 catalyst was related to the partial migration of Cu X O species to the surface of the NPs, also confirmed through in-situ UV–Vis spectroscopy. The favorable role played by the TiO 2 reducibility was established through in-situ Raman spectroscopy. Moreover, findings obtained by DFT confirmed the experimentally evidenced structural modifications. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To describe the incidence and characterize the clinical manifestations, diagnosis and outcome of spontaneous epidural abscess (SEA) not associated with neurosurgical procedures or instrumentation of the spine. Methods: Review of cases of SEA over 10 years. Diagnosis was made by imaging-techniques and surgical examination. Results: Fifteen patients were studied. The incidence of SEA was 0.4 cases per 100,000 person-years. Infection gained access to the epidural space haematogenously in 9 patients (60%). SEA was located at the lumbar (7 cases), cervical (4), cranial (2) and thoracic (1) areas. Local pain was the most common manifestation (93.3%); fever was absent in 40%. One third did not show neurologic abnormalities. Staphylococcus aureus was the most commonly isolated agent (87% of cases). All the patients received antimicrobial therapy for a mean period of 6.1±3.9 weeks. In addition, open surgical drainage or CT-guided needle aspiration was successfully performed in 10 and 3 patients respectively. Two patients were managed with antibiotics alone. Poor outcome occurred more frequently in patients with abscess at higher levels (67% in cranial or cervical abscesses versus 0% in thoracic or lumbosacral abscesses). An association was found between delayed diagnosis and poor outcome (p <0.05). Overall, 54% of our patients recovered without sequelae. Conclusions: SEA resulted from the extension of nearby or distant infections into the epidural space. Diagnosis was frequently delayed and the patient''s neurologic status at presentation was the most important predictor of the outcome. The onset of spinal pain in patients with focal infections should prompt MRI of the spine, even in the absence of neurologic abnormalities or fever. [Copyright &y& Elsevier]

In this work, we tested whether L-type Ca(2+ )channels are involved in the increase of caffeine-evoked tension in frog slow muscle fibers. Simultaneous net Ca(2+) fluxes and changes in muscle tension were measured in the presence of caffeine. Isometric tension was recorded by a mechanoelectrical transducer, and net fluxes of Ca(2+) were measured noninvasively using ion-selective vibrating microelectrodes. We show that the timing of changes in net fluxes and muscle tension coincided, suggesting interdependence of the two processes. The effects of Ca(2+)channel blockers (verapamil and gadolinium) were explored using 6 mM: caffeine; both significantly reduced the action of caffeine on tension and on calcium fluxes. Both caffeine-evoked Ca(2+) leak and muscle tension were reduced by 75% in the presence of 100 microM: GdCl(3), which also caused a 92% inhibition of net Ca(2+) fluxes in the steady-state condition. Application of 10 microM: verapamil to the bath led to 30% and 52% reductions in the Ca(2+)leak caused by the presence of caffeine for the peak and steady-state values of net Ca(2+) fluxes, respectively. Verapamil (10 microM): caused a 30% reduction in the maximum values of caffeine-evoked muscle tension. Gd(3+)was a more potent inhibitor than verapamil. In conclusion, L-type Ca(2+) channels appear to play the initial role of trigger in the rather complex mechanism of slow fiber contraction, the latter process being mediated by both positive Ca(2+)-induced Ca(2+ )release and negative (Ca(2+) removal from cytosol) feedback loops. [ABSTRACT FROM AUTHOR]

The improvement of performance in sodium ion batteries is a subject of intense research. In this work, a first principle calculations study at the density functional level on the adsorption process of Na adatoms into Sb2S3/carbon (Sb2S3/CM) and Sb2S3/heteroatom doped‐carbon (Sb2S3/S‐CM, Sb2S3/Sb‐CM) is presented. The sulfur and antimony doped‐carbon substrates enhance the adsorption energies, charge transfer, specific capacities and the diffusion properties of Na adatoms into the Sb2S3/S‐CM and Sb2S3/Sb‐CM composite systems. The Na storage capacity trend and the open circuit voltage profile follows the trend observed in previous experimental results. This work explores perspectives through tailoring 2D carbon anodes with doping heteroatoms in the presence of adsorbed Sb2S3 for an outstanding storage capacity and cycling stability architecture. [ABSTRACT FROM AUTHOR]

This work gives new evidence on the structural properties of tetragonal hybrid perovskites obtained from different experimental routes of synthesis, and the theoretical elucidation of their electronic structure properties in accordance to the formation of the energy band gaps. Two different synthesis routes to prepare hybrid perovskites of the form (CH 3 NH 3 PbI 3) have been performed. The final crystal structure depends on the conditions of the preparation method that give the perovskite a twisted or regular molecular structure. This was certified by the structural analysis, normal modes of vibration, and opto-electronic properties. Moreover, the elucidation of electronic structure properties were also analyzed by a first principles study. That is, density functional theory (DFT) calculations revealed the structure configuration of twisted hybrid perovskites CH 3 NH 3 PbI 3 , in combination with XRD evidence. The electronic structure properties of the systems under study are mainly ruled by the geometrical disposition of the organic cation, whose different degrees of freedom are intimately related to the size of the energy band gap, and also to the magnitude of the work function. The DFT analysis with the experimental characterization of these hybrid perovskite systems could aid to tailor novel materials intended to be applied in the new generation of solar cell devices. That is, our combined methodology could contribute to modify the structure of perovskites with improved electronic properties for solar energy applications. [Display omitted] • The slow solvent evaporation process showed an iodine atom deviation. • CH 3 NH 3 PbI 3 optoelectronic properties were impacted by two synthesis methods. • DFT calculations revealed that the organic cation plays a role on gap formation. • Theoretical work functions are sensitive to the atomic interactions with the substrate. • Absorption spectra showed that twisted perovskites could act as an absorber material. [ABSTRACT FROM AUTHOR]

Increasing the electrochemical performance of electrode materials in sodium ion batteries (NIBs) remains a major challenge. Here, a combined experimental and theoretical investigation on the modification induced by Sb 2 S 3 embedded in a heteroatom-doped 3D carbon matrix (CM) for efficient anodes in NIBs is presented. The structural and chemical characterization demonstrates the successful doping of 3D CM with S and Sb atoms. When evaluated as anode materials for NIBs, the heteroatom-doped nanocomposites delivered a better cycling stability and superior rate capability than those of undoped Sb 2 S 3 /CM anodes. First principle calculations were used at the Density Functional Theory level to systematically study the Sb 2 S 3 /CM and Sb 2 S 3 /heteroatom doped-CM composites, as NIBs anodes. Doping the carbon substrate by heteroatoms improved the adsorption of Sb 2 S 3 on the matrix and allowed for ionic/covalent attraction with the Sb 2 S 3 nanoparticle, respectively. Such results could be used to model the stabilty of the composite architectures observed in the experiment, for superior cycling stability. [ABSTRACT FROM AUTHOR]

This work compares the effect of using a solar reactor against a conventional electrical furnace to obtain carbon materials by pyrolysis of a lignocellulosic precursor. The solar reactor is directly irradiated and includes modifications to improve the control of the process and the reproducibility of solar experiments. A bagasse of agave creole was selected as the lignocellulosic precursor or biomass to obtain carbon materials at temperatures of 700 °C. Comparing carbons produced by conventional and solar pyrolysis, higher crystallinity and lower hydrophilicity are evident in the former. Moreover, conventional pyrolysis tends to promote a more homogeneous porous structure in comparison to solar pyrolysis. However, within the spectrum of solar carbons produced, the morphology of biomass plays a crucial role in influencing the chemical composition and porosity properties. Specifically, the use of fibers instead of powders to produce carbons through solar pyrolysis results in a more homogeneous porosity, attributed to an enhanced volumetric absorption of solar radiation. This modification leads to a significant improvement in capacitance, increasing from 125 F/g to 175 F/g at 5 mV/s in aqueous electrolytes. The carbons from the solar furnace are reproducible, underlying the potential of the proposed process towards a sustainable alternative. To achieve a theoretical reference, the pyrolysis process was mimic trough Reactive Molecular Dynamics calculations modeling the initial structural conditions of agave biomass with its corresponding lignocellulosic components and considering analogous thermal conditions. The resulting carbon structures at the end of the simulations showed structural properties that are consistent with those observed in the pair distribution functions obtained from XRD and the pore size distribution from physisorption analyses. This combined experimental–theoretical approach offers the potential to elucidate porous carbon structures derived from pyrolysis processes powered by solar radiation. This method can help in the design and identification of lignocellulosic structures in biomass, with the resulting carbon materials suitable for energy storage applications. • Solar reactors are a sustainable alternative to the use of conventional reactors. • Comparison among carbon materials obtained in solar and tubular furnaces was studied. • Different furnaces produced carbon materials with different properties. • Solar furnace produced reproducible materials. • Tubular furnace was better to obtain carbon materials with a higher surface. • This study allowed for a better understanding of the solar production of carbon. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, novel solar cell materials are studied by using first-principle calculations to improve the electronic structure properties and thus enhance the hypothetical efficiency in the active layer of dye-sensitized solar cells (DSSCs). The modeling of 75 composite systems is explored, based on the interaction of three molecular structures; namely graphene, a linker, and metalated porphyrins (a base species and the coordinated cases with Mg, Cu, Ni, and Zn). The stability and electronic structure properties of 10 composite systems, screened from the original set, were analyzed as potential candidates to be implemented in solar cell devices. All calculations were performed using density functional theory (DFT). This study is intended to screen systems that broaden the range of the absorption spectra in the composite materials of the form porphyrin/carbon by improving the electron transfer properties. The methodology to obtain the final set of selected composite materials may be considered a guide in the design of novel DSSC systems. [Display omitted] • DFT calculations forecasted novel carbon-based materials for solar cells applications. • Metalated porphyrins with functionalization and supported on graphene are stable. • Simulated absorption spectra revealed blue-shift after porphyrin functionalization. • Charge transfer at the interface induces an attraction of the van der Waals type. • A theoretical method may aid in the in silico design of sustainable DSSC materials. [ABSTRACT FROM AUTHOR]

A Density Functional study predicting a heterogeneous-catalyzed reaction to obtain biodiesel was performed. Triacetin simulated triglycerides in the presence of an Au(1 1 1) surface as the heterogeneous catalyst. Methoxy was implemented as alcohol solvent to understand the reaction trajectory along a three-step transesterification process. Reactants and products in the three-step process are adsorbed on the Au substrate through non-covalent interactions of the electrostatic-type, which are also mediated by a van der Waals attraction. Density of states indicated that the electronic structure nature of Au is preserved after the interaction with the organic moieties. This may be addressed to an enhanced stability of the Au(1 1 1) catalyst through the overall reaction. Charge transfer analysis revealed that the Au surface oxidation aids in the transesterification of triacetin and evidences that gold plays an important role in this catalytic process. Such results may provide fundamental insights into the design of heterogeneous catalysts for biodiesel production. [ABSTRACT FROM AUTHOR]

Composite materials consisting of TiO 2 and graphene (TiO 2 /GR) have exciting properties that could make them suitable as anode material for Li-ion batteries. Systematic density functional theory (DFT) calculations were performed to investigate the TiO 2 /GR energy-storage mechanism, adsorption sites and diffusion pathways of Li ions in TiO 2 /GR. Its interface and the region outside graphene were studied for identifying stable surface sites. The adsorption energies are dominated by van der Waals interactions. Li diffusion along the graphene plane was the most favorable with a diffusion energy barrier of 0.24 eV, whereas the probability of diffusion at the interface is low, due to the barrier of 3 eV. The composite exhibited a higher specific charge-storage capacity than other van der Waals heterostructures. The TiO 2 /GR interface retains a large amount of charge implying that the TiO 2 /GR composite shows suitable electrochemical properties for use as anode in lithium-ion batteries. • DFT calculations explained energy storage processes in composite anodes. • The interaction at the TiO 2 /GR interface is mainly ruled by vdW effects. • Diffusion pathways of Li showed possible intercalation mechanisms in TiO 2 /GR anodes. • The potential 3.35V(Max)/1.85(Min) on TiO 2 /GR is adequate for electronic devices. [ABSTRACT FROM AUTHOR]

Introduction: Brain-derived neurotrophic factor (BDNF) protein expression is sensitive to cellular activity. In the sedentary state, BDNF expression is affected by the muscle phenotype.Methods: Eighteen Wistar rats were divided into the following 3 groups: sedentary (S); moderate-intensity training (MIT); and high-intensity training (HIT). The training protocol lasted 8 weeks. Forty-eight hours after training, total RNA and protein levels in the soleus and plantaris muscles were obtained.Results: In the plantaris, the BDNF protein level was lower in the HIT than in the S group (P < 0.05). A similar effect was found in the soleus (without significant difference). In the soleus, higher Bdnf mRNA levels were found in the HIT group (P < 0.001 vs. S and MIT groups). In the plantaris muscle, similar Bdnf mRNA levels were found in all groups.Conclusions: These results indicate that high-intensity chronic exercise reduces BDNF protein level in fast muscles and increases Bdnf mRNA levels in slow muscles. [ABSTRACT FROM AUTHOR]

Organic solar cell nanomaterials are molecular systems that have been recently incorporated in devices with remarkable properties and high efficiencies. A systematic theoretical study based on density functional theory and non-equilibrium Green's functions was performed to elucidate the electron transport behavior on solar cell materials. The I − V profiles based on the transmission obtained from the electronic density revealed an appropriate performance in simulated conditions of sunlight irradiation, while in dark conditions such systems may behave as a diode. The current methodology may represent a tool to select and design high performance materials for the new generation of solar cell devices. [Display omitted] • Organic photovoltaic molecules were screened by their photoisomerization properties. • DFT revealed the transmission behavior at ground/excited states in screened systems. • Ground and excited states may represent dark/illumination conditions, respectively. • Electron transport in OPV systems could be finely simulated with a ballistic model. • The theoretical model may aid to identify OPV systems with improved performance. [ABSTRACT FROM AUTHOR]

Sparganosis is a severe parasitic infection caused by the larvae of Spirometra mansoni, also called 'sparganum.' In human hosts, the Spirometra mansoni larva commonly targets the subcutaneous tissue or muscle. Sometimes it can also migrate into the brain, resulting in cerebral sparganosis, mainly characterized by focal neurological symptoms such as seizures and radiological 'wandering lesions' on magnetic resonance images (MRIs). Clinical cases of cerebral sparganosis have been reported worldwide, mainly in Asian countries, but also in North America, South America and Australia. Only two cases have been previously reported in Europe. A 29-year-old male from Bolivia, who lived in Spain, presented to our service for seizures and a multicystic brain lesion, initially suspected to be a dysembryoplastic neuroepithelial tumor (DNET). He underwent gross total resection of the mixed solid/cystic lesion. Pathology revealed gliosis, multiple interconnected cystic cavities with fibrous walls, inflammatory cell infiltration and no necrotizing granulomatous reaction. Inside the cavities, a parasitic form was identified as the larva of the cestode Spirometra mansoni. At 1-year follow-up, the patient had no deficits and was seizure free. Clinicians should be alerted to the possible existence of this rare entity in Europe, especially in patients from endemic areas with a possible infection history as well as 'wandering lesions' on the MRI. [ABSTRACT FROM AUTHOR]

Pristine γ -graphyne (γ -GY) is a widely known two-dimensional system that has a high Li, Na, and K adsorption capacity with high energy barriers for the diffusion of such metal ions. In this work, we used dispersion-corrected density functional theory calculations to investigate the electronic effect of Au-doped γ -graphyne (GYE-Au and GY-Au) monolayers on the adsorption and diffusion of M metal-ions (M = Li, Na, and K). The nature of the electronic structure of the GYE-Au monolayers corresponds to a semi-metallic behavior. According to climbing image nudge elastic band calculations, low activation energies in the diffusion of M atoms are associated with the presence of the Au atom with respect to the γ -GY monolayer. High adsorption energy values were associated with the storage capacity of the GYE-Au monolayers. The electronic storage properties such as open circuit voltage and theoretical specific capacity were improved in the GYE-Au monolayers. This study shows that, at an atomistic level, the GYE-Au monolayers could be an excellent 2D anode material for Li, Na, and K-ion batteries. [Display omitted] • Novel graphyne monolayers with Au-heteroatom were theoretically predicted. • The Li+, Na+, and K+ ions can be absorbed at sites close to the Au atom. • The effect of the Au atoms reduces energy barriers in alkaline ions diffusion. • B, N, and Au dopants improve the diffusion coefficient with respect to the graphyne. • Specific capacities are competitive with respect to known 2D anode materials. [ABSTRACT FROM AUTHOR]

A combined theoretical and experimental work was performed to assess the carbon dioxide (CO 2) evolution reaction into short chain hydrocarbons. The theoretical calculations were performed by using Density Functional Theory (DFT) at the DFT + U level. The reaction mechanisms were elucidated with the string method by comparing the photocatalytic behavior of the pristine Ti-NT surface, previously synthesized in our group, and the M -doped Ti-NT (M -Ti-NT, where M = Cu, Ni) systems. For the pristine material, the results showed lower adsorption energies of the CO 2 molecule (−0.27 eV), as compared to that obtained with the M -doped Ti- NT systems. Ni-Ti-NT showed an enhancement in photocatalytic performance with respect to the other surfaces, by yielding small activation energies throughout the reaction path. On the experimental side, Ti-NT and M -Ti-NT (M = Cu, Ni) materials were characterized through several techniques to assess their structural, morphological, textural, and optoelectronic properties. The photocatalytic CO 2 reduction was evaluated under wavelength illumination between 440–540 nm. The liquid solar fuel identified products were HCOOH, CH 2 O, and CH 3 OH, showing a different distribution among photocatalysts which correlates with the position of the conduction band of the photocatalysts. Doping with Cu and Ni of the Ti-NT structure enhances the carriers' density which improves the photoactivity mainly in the case of Ni-Ti-NT. The photocatalytic experimental results agree with the theoretical calculations. [Display omitted] • DFT calculations evidence the CO 2 reduction path on modified M–Ti–NT-based material. • Ni and Cu doping tunes the optoelectronic properties of Ti–NT. • Enhanced charge carriers density in M–Ti–NT improves the CO 2 conversion. • Ni–Ti–NT exhibits better photocatalytic activity. • Experimental evidence agrees with the proposed simulated reaction mechanism. [ABSTRACT FROM AUTHOR]

In this work, Density Functional Theory (DFT) calculations were performed to assess the photo-catalytic properties of hematite (α -Fe 2 O 3) and the atomistic modeling of the CO 2 conversion mechanism to organic molecules on such a surface. The reaction pathways for the CO 2 simulated photo-transformation were modeled with the string method. The reaction mechanism obtained by DFT calculations evidenced the H 2 O 2 molecules reduction instead of the CO 2 reduction at the first step, inducing • OH radical formation. The following CO 2 activation is induced by the addition of the • OH radical through one of the π ∗ bonds of CO 2 molecule, unlike the commonly reported CO 2 reduction, resulting in the bicarbonate anion. The emergence of carbonic acid is followed by carbon reduction reactions up to methanol. According to the adsorption energies and topological analysis of the bond critical points, the intermediates exhibited closed-shell interactions with the hematite surface. Electronic structure properties were evaluated at the DFT+ U ＋ J level. Opto-electronic parameters were also evaluated experimentally; giving validity to the results obtained by the DFT. This work also shows the first theoretical insight into the conversion of CO 2 with H 2 O 2 into H 2 CO 3 , HCOOH, CH 2 O and CH 3 OH on the hematite (1 1 0) surface. Additionally, to support the theoretical elucidation, a mixture of iron oxides (Fe 2 O 3 - FeOOH) nanoparticles were prepared in accordance to recent published results suggesting a heterogeneous catalytic process, instead a homogeneous Fenton's method to evaluate the photocatalytic properties and the redox-potential to degrade CO 2. One of the predominant phases observed in the iron oxide mixture corresponds to hematite. Moreover, the photocatalytic process of CO 2 conversion with iron oxide nanoparticles was experimentally performed. The formation of methanol was evidenced via FTIR analysis. [Display omitted] • Hematite in the presence of H 2 O 2 is suitable for CO 2 conversion to organic compounds. • DFT+U+J approach accurately predicts electronic properties of hematite structure. • Simulation predicts photocatalytic potential of hematite surface for CO 2 conversion. • CO 2 activation in photocatalysis can be achieved by addition reaction in one step. • CO 2 photocatalysis on a α -Fe 2 O 3 surface is theoretically and experimentally verified. [ABSTRACT FROM AUTHOR]

This paper focuses on family involvement in the education of teenagers at risk of dropping out from compulsory secondary school. A questionnaire was completed by 131 Spanish and Cypriot families with children at six schools - three in each country. The questionnaire investigated: (1) parental perceptions of their children's activities in their free time; (2) academic expectations for their children; (3) parental concern regarding their children's education; and (4) parent-teacher interactions. Descriptive measures and t-test comparative analyses between Spain and Cyprus were undertaken. Results show that these families have an encouraging attitude towards their teenagers. Nonetheless, significant statistical differences between Spanish and Cypriot parents suggest that the Spanish families have a more protective parenting style than the Cypriot families. The study points to the lack of support for these families as regards advice and stimulation for their children at home, and to the need to promote school-family partnerships. [ABSTRACT FROM AUTHOR]

We tested whether the absence of an inward rectifier channel in slow skeletal muscle fibers of the frog is regulated by innervation. Normal and denervated slow fibers were identified according to their passive electrical properties. In current-clamp experiments, anomalous rectification was quantified as the ratio of effective resistances for hyperpolarizing and depolarizing pulses. In isotonic potassium solution, this ratio was 0.45 ± 0.1 (n = 14) for twitch fibers, whereas slow fibers displayed linear behavior [ratio = 1.0 ± 0.05 (n = 15)]. However, denervated slow fibers showed anomalous rectification (ratio, 0.48 ± 0.07; n = 5). This finding was supported by voltage-clamp experiments in which denervated slow fibers displayed (1) an inward rectifier current during hyperpolarizing pulses, (2) an increase in this current when [K+]o was increased, and (3) a current inhibition after application of Ba2+. These results suggest that frog slow fibers, which normally do not possess inward rectifier channels, can express them after denervation. [Copyright &y& Elsevier]

In higher plants the vacuolar K+‐selective (VK) channel was identified solely in guard cells. This patch‐clamp study describes a 40 pS homologue of the VK channel in Beta vulgaris taproot vacuoles. This voltage‐independent channel is activated by submicromolar Ca2+, and is ideally selective for K+ over Cl– and Na+. [ABSTRACT FROM PUBLISHER]

The use of glycerol as an added-value by-product from the transesterification of triglycerides to produce biodiesel has been the subject of intense research due to its versatility in a wide range of applications. In this work, a theoretical study at the density functional theory (DFT) level to categorize the most probable routes to achieve glycerol conversion was performed. Gibbs free energies were computed to assess the feasibility of the steps involved in experimental glycerol carbonate synthesis from glycerol and dimethyl carbonate. The cyclization from methyl glycerol carbonate anion to glycerol carbonate is reasonable due to the computation of the Gibbs free energy amounting to -310.0 kcal/mol, which indicates an exothermic reaction with the spontaneous rising of glycerol carbonate. The assessment of the molecular dimensions at the optimized geometry of glycerol carbonate showed a critical diameter and length of 5.25 Å and 5.90 Å, respectively; with a volume of 127.7 Å 3. Charge population analysis provided insights into the electronic transfer during the reaction and the bonding mechanism resulting in the products. Additionally, the heterogeneous catalysis reaction involved in the glycerol carbonate evolution reaction and its subproducts was studied on a periodic surface model of the oil palm fuel ash catalyst in order to evaluate activation energies and the feasibility of the proposed mechanism. That is, the computations revealed an activation energy barrier of 13.4 kcal/mol (0.58 eV), which also certifies the cyclization feasibility in the formation of glycerol carbonate. The results may contribute in the i n s i l i c o design of the experimental setup to improve efficiency in the process of transesterification reaction of glycerol and dimethyl carbonate to valuable glycerol carbonate. [Display omitted] • Quantum chemistry aids to improve efficiency on the conversion of glycerol carbonate. • Gibbs energies revealed the feasibility of the reaction steps in glycerol conversion. • Electronic density explains the mechanism of reaction to obtain a fuel additive. • Glycerol heterogeneous catalysis mechanism on OPFA surface are theoretically revealed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Photocatalytic potential of the Cu 2 O for (1 0 0), (1 1 0) and (1 1 1) facets is explored. • Cu 2 O(1 0 0) facet shows a high photocatalytic potential in the conversion of CO 2. • The reaction mechanism of the CO 2 towards methanol and methane is evaluated. • Simulations aids to understand the efficient conversion of CO 2 on the Cu 2 O(1 0 0) facet. In this work, Density Functional Theory (DFT) calculations were performed to elucidate the photocatalytic potential of Cu 2 O surfaces. Three slab models of the (1 0 0), (1 1 0) and (1 1 1) facets were studied by considering their optical and electronic structure properties, and photocatalytic potential. The results showed that Cu 2 O (1 0 0) and (1 1 1) surfaces e excellent candidates to be used in a photocatalytic processes to reduce CO 2 to form some hydrocarbon derivatives. Based on the photocatalytic potential analysis, the Cu 2 O(1 0 0) slab model was implemented to simulate the CO 2 reduction reaction evolution into methanol and methane with the String methodology. The results showed that such Cu 2 O facet could be efficiently implemented to improve the CO 2 photoreduction process. Additionally, this theoretical model could also be implemented to tailor novel photocatalytic materials to produce sustainable solar fuels. [ABSTRACT FROM AUTHOR]

In this paper we describe the synthesis of nanoscale grains of the p -type semiconductor Cu 3 BiS 3 (CBS) and its material properties. Seed-like nanograins of length ~250 nm with orthorhombic wittichenite structure were obtained through the simple solvothermal reaction of CuCl, Bi(NO 3) 3 and sulfur in ethylene diamine. The obtained nanomaterial is of single phase without traces of any impurities as confirmed by XRD, XPS, Raman spectroscopy, and TEM Fourier transform analysis. The material has a band gap 1.4 eV. The Seebeck coefficient is ~450 μV/K, which is in the range of that reported for CBS synthesized by hot pressing the components Cu, Bi and S. With the aid of Density Functional theory, the electronic structure properties of the material are evaluated to derive some photovoltaic parameters of interest. The band alignments of the CBS system with known n-type window materials such as CdS, ZnO, ZnS, CdS/ZnO, CdS/ZnS and TiO 2 , were also studied to evaluate the prospect of heterojunction solar cells based on CBS absorber. This may represent a theoretical methodology to design heterojunctions with adequate window materials that enhance the performance of solar cells. [Display omitted] • Cu 3 BiS 3 nanoparticles were synthesized by surfactant free solvothermal method. • Phase-pure orthorhombic Cu 3 BiS 3 with stoichiometric composition was obtained. • A theoretical elucidation of the electronic structure properties of Cu 3 BiS 3 was performed. • Possible window materials are identified based on band edge calculations. [ABSTRACT FROM AUTHOR]

• A theoretical DFT methodology may be used to tailor novel solar cell devices. • Lowest-energy structures at ground and excited states were computed in OPV materials. • Dihedral angles related to shifting of absorption maxima in UV–vis simulated spectra. • Descriptors obtained from electronic structure may aid to improve PV efficiencies. A density functional theory study was performed on a series of organic photovoltaic materials with a promising potential to be implemented as the active layer in a solar cell device. A thorough analysis on the molecular structure at ground and excited state revealed that some of the systems in the series of molecules observed in the ground state is dramatically altered in the first excitation. The dihedral deviations could be addressed as a ruling mechanism behind isomerization and its influence in the opto-electronic properties. The computation of absorption spectra at ground and excited state geometries showed a significant shift in the absorption maxima, presumably due to such geometrical changes. Furthermore, the computation of dipole moments gave us insights into the possible charge transfer from the OPV material to an acceptor in a solar cell device. This is critical when the system is implemented in such a device. Additionally, relevant photovoltaic parameters were collected, and a candidate series of OPV systems was proposed as potential materials for the heterojunctions of a solar cell device. The given theoretical methodology and the photovoltaic data computationally obtained may aid in the in silico design of novel donor materials for the new generation of solar cells. [ABSTRACT FROM AUTHOR]

A systematic theoretical study on graphene oxide model systems was performed with Density Functional Theory (DFT), and supported by experimental evidence. The results revealed that graphene is highly susceptible to be decorated with organic functional groups, which induced the formation of a band gap, and the rising of a novel semiconducting character. This novel property was used to explore the possible photocatalytic potential in the model systems under study. That is, we evaluated work functions to theoretically obtain the energies of the valence band maximum and the conduction band minimum with respect to the normal hydrogen electrode potential. The assessment of UV-vis profile via Time-dependent DFT also showed the potential of the model systems to efficiently absorb sun light irradiation under photocatalytic conditions. Moreover, the results showed that it is possible to tune the photocatalytic potential of the graphene oxide models under study by interchanging the functional groups anchored on the graphene surface, and their corresponding contents ratio. Experimental evidence obtained via the measurement of optoelectronic properties, revealed that it is possible to classify a graphene oxide powder into one of the model systems under study, while a photocatalytic procedure performed in our laboratory, showed the facile photoreduction of formic acid into methanol with such a graphene oxide. Consequently, the prediction of the electronic structure properties is expected. This may represent a tool to design materials based on graphene oxide to be implemented in reactors for photocatalytic applications. [ABSTRACT FROM AUTHOR]

The deterioration of food quality during food processing has been the subject of intense research. Changes in the secondary metabolites present in foodstuff have been identified during drying (phenolic and anthocyanin compounds). To explain the effect of temperature on the phenolic and anthocyanin content in strawberries during drying, a molecular dynamics simulation study at the Density Functional Theory (DFT) level was performed and validated with experimental data. Solar drying and tray drying at different temperatures were investigated. The total phenolic compounds (TPC), anthocyanins, and antioxidant activity were measured. Aromaticity indexes were obtained to rank the stability during the simulated drying process. The changes observed in the aromatic behavior were related to destabilization of the compounds, which leads to the degradation process observed experimentally. These results are of utility in the selection of the operating conditions to prevent TPC deterioration and to understand the role played by the electronic structure properties of anthocyanin molecules on their degradation. • DFT calculations gave insights into the understanding of anthocyanin degradation. • AIMD simulations explored possible routes of anthocyanin evolution during drying. • A combined method may aid into the design of food processing subjected to drying. • Total phenolic compounds and anthocyanins were influenced by the drying temperature. • Exposure time are related to changes in phenolic compounds formation. [ABSTRACT FROM AUTHOR]