Optical Properties of Graphene Nanoflakes: Shape Matters

In recent years there has been significant debate on whether the edge type of graphene nanoflakes (GNF) or graphene quantum dots (GQD) are relevant for their electronic structure, thermal stability and optical properties. Using computer simulations, we have proven that there is a fundamental difference in the calculated absorption spectra between samples of the same shape, similar size but different edge type, namely, armchair or zigzag edges. These can be explained by the presence of electronic structures near the Fermi level which are localized on the edges. These features are also evident from the dependence of band gap on the GNF size, which shows three very distinct trends for different shapes and edge geometries.Comment: 8 pages, 9 figures. Submitted to The Journal of Chemical Physic

Fully Ab initio Simulations of Tip Enhanced Raman Scattering Reveal Active Role of Substrate on High-Resolution Images

Tip-enhanced Raman scattering (TERS) has emerged as a powerful tool to obtain subnanometer spatial resolution fingerprints of atomic motion. Theoretical calculations that can simulate the Raman scattering process and provide an unambiguous interpretation of TERS images often rely on crude approximations of the local electric field. In this work, we present a novel and fully ab initio method to compute TERS images by combining Time Dependent Density Functional Theory (TD-DFT) and Density Functional Perturbation Theory (DFPT) to calculate Raman cross sections with realistic local fields. We present TERS results on the benzene and the TCNE molecule, the latter adsorbed at Ag(110). We demonstrate that chemical effects on adsorbed molecules, often ignored in TERS simulations, dramatically change TERS images. This calls for the inclusion of chemical effects for predictive theory-experiment comparisons and understanding of molecular motion at the nanoscale

Dynamical evolution of the Schottky barrier as a determinant contribution to electron–hole pair stabilization and photocatalysis of plasmon-induced hot carriers

The harnessing of plasmon-induced hot carriers promises to open new avenues for the development of clean energies and chemical catalysis. The extraction of carriers before thermalization and recombination is of fundamental importance to obtain appealing conversion yields. Here, hot carrier injection in the paradigmatic Au-TiO2 system is studied by means of electronic and electron-ion dynamics. Our results show that pure electronic features (without considering many-body interactions or dissipation to the environment) contribute to the electron–hole separation stability. These results reveal the existence of a dynamic contribution to the interfacial potential barrier (Schottky barrier) that arises at the charge injection pace, impeding electronic back transfer. Furthermore, we show that this charge separation stabilization provides the time needed for the charge to leak to capping molecules placed over the TiO2 surface triggering a coherent bond oscillation that will lead to a photocatalytic dissociation. We expect that our results will add new perspectives to the interpretation of the already detected long-lived hot carrier lifetimes and their catalytical effect, and concomitantly to their technological applications

La història econòmica de l'Espanya contemporània fins la guerra civil: principals aportacions

L'únic historiador que ha formulat un model global de l'economia castellana de l'antic règim és Gonzalo Anes. Aplicant, com afirma ell mateix, «el modelo macroeconómico clásico de distribución de la renta que, como es bien sabido, puede ser considerado como un modelo de desarrollo económico», estudia les transformacions operades en l'agricultura castellana a través de diferents variables: població, preus, producció, intercanvis i rendes. Les investigacions dutes a terme per G. Anes, seguint el model establert per Ernest Labrousse per a analitzar el funcionament de l'economia francesa durant l'antic règim, permeten l'establiment de determinades conclusions, respecte a l'economia senyorial castellana

DFTB+, a software package for efficient approximate density functional theory based atomistic simulations

DFTB+ is a versatile community developed open source software package offering fast and efficient methods for carrying out atomistic quantum mechanical simulations. By implementing various methods approximating density functional theory (DFT), such as the density functional based tight binding (DFTB) and the extended tight binding method, it enables simulations of large systems and long timescales with reasonable accuracy while being considerably faster for typical simulations than the respective ab initio methods. Based on the DFTB framework, it additionally offers approximated versions of various DFT extensions including hybrid functionals, time dependent formalism for treating excited systems, electron transport using non-equilibrium Green’s functions, and many more. DFTB+ can be used as a user-friendly standalone application in addition to being embedded into other software packages as a library or acting as a calculation-server accessed by socket communication. We give an overview of the recently developed capabilities of the DFTB+ code, demonstrating with a few use case examples, discuss the strengths and weaknesses of the various features, and also discuss on-going developments and possible future perspectives

Spatial distribution of cerebral white matter lesions predicts progression to mild cognitive impairment and dementia

CONTEXT White matter lesions (WML) increase the risk of dementia. The relevance of WML location is less clear. We sought to determine whether a particular WML profile, based on the density and location of lesions, could be associated with an increased risk of mild cognitive impairment (MCI) or dementia over the following 7 years. METHODS In 426 healthy subjects from a cohort of community-dwelling people aged 65 years and over (ESPRIT Project), standardized cognitive and neurological evaluations were repeated after 2, 4 and 7 years. Patterns of WML were computed with a supervised data mining approach (decision trees) using the regional WML volumes (frontal, parietal, temporal, and occipital regions) and the total WML volume estimated at baseline. Cox proportional hazard models were then constructed to study the association between WML patterns and risk of MCI/dementia. RESULTS Total WML volume and percentage of WML in the temporal region proved to be the best predictors of progression to MCI and dementia. Specifically, severe total WML load with a high proportion of lesions in the temporal region was significantly associated with the risk of developing MCI or dementia. CONCLUSIONS Above a certain threshold of damage, a pattern of WML clustering in the temporal region identifies individuals at increased risk of MCI or dementia. As this WML pattern is observed before the onset of clinical symptoms, it may facilitate the detection of patients at risk of MCI/dementia.The ESPRIT Project is financed by the regional government of Languedoc-Roussillon (http://www.laregion.fr), the Agence Nationale de la Recherche (ANR: http://www.agence-nationale-recherche.fr) and an unconditional grant from Novartis (http://www.novartis.fr). This study is also supported by France Alzheimer (http://www.francealzheimer.org/)

Mutations in the heat-shock protein A9 (HSPA9) gene cause the EVEN-PLUS syndrome of congenital malformations and skeletal dysplasia.

We and others have reported mutations in LONP1, a gene coding for a mitochondrial chaperone and protease, as the cause of the human CODAS (cerebral, ocular, dental, auricular and skeletal) syndrome (MIM 600373). Here, we delineate a similar but distinct condition that shares the epiphyseal, vertebral and ocular changes of CODAS but also included severe microtia, nasal hypoplasia, and other malformations, and for which we propose the name of EVEN-PLUS syndrome for epiphyseal, vertebral, ear, nose, plus associated findings. In three individuals from two families, no mutation in LONP1 was found; instead, we found biallelic mutations in HSPA9, the gene that codes for mHSP70/mortalin, another highly conserved mitochondrial chaperone protein essential in mitochondrial protein import, folding, and degradation. The functional relationship between LONP1 and HSPA9 in mitochondrial protein chaperoning and the overlapping phenotypes of CODAS and EVEN-PLUS delineate a family of "mitochondrial chaperonopathies" and point to an unexplored role of mitochondrial chaperones in human embryonic morphogenesis

Different Storing and Processing Conditions of Human Lymphocytes do not Alter P-Glycoprotein Rhodamine 123 Efflux

P-glycoprotein (Pgp), a protein codified by Multi Drug Resistance (MDR1) gene, has a detoxifying function and might influence the toxicity and pharmacokinetics and pharmacodynamics of drugs. Sampling strategies to improve Pgp studies could be useful to optimize the sensitivity and the reproducibility of efflux assays. This study aimed to compare Pgp expression and efflux activity by measuring Rhodamine123 (Rh123) retention in lymphocytes stored under different conditions, in order to evaluate the potential utility of any of the storing conditions in Pgp functionality. Our results show no change in protein expression of Pgp by confocal studies and Western blotting, nor changes at the mRNA level (qRT-PCR). No differences in Rh123 efflux by Pgp activity assays were found between fresh and frozen lymphocytes after 24 hours of blood extraction, using either of the two Pgp specific inhibitors (VP and PSC833). Different working conditions in the 24 hours post blood extraction do not affect Rh123 efflux. These results allow standardization of Pgp activity measurement in different individuals with different timing of blood sampling and in different geographic areas. ______________

Cortical-Bone Fragility - Insights from sFRP4 Deficiency in Pyle's Disease

BACKGROUND Cortical-bone fragility is a common feature in osteoporosis that is linked to non - vertebral fractures. Regulation of cortical-bone homeostasis has proved elusive. The study of genetic disorders of the skeleton can yield insights that fuel experimental therapeutic approaches to the treatment of rare disorders and common skeletal ailments. METHODS We evaluated four patients with Pyle’s disease, a genetic disorder that is characterized by cortical-bone thinning, limb deformity, and fractures; two patients were examined by means of exome sequencing, and two were examined by means of Sanger se - quencing. After a candidate gene was identified, we generated a knockout mouse model that manifested the phenotype and studied the mechanisms responsible for altered bone architecture. RESULTS In all affected patients, we found biallelic truncating mutations in SFR P4 , the gene encoding secreted frizzled-related protein 4, a soluble Wnt inhibitor. Mice deficient in Sfrp4 , like persons with Pyle’s disease, have increased amounts of trabecular bone and unusually thin cortical bone, as a result of differential regulation of Wnt and bone morphogenetic protein (BMP) signaling in these two bone compartments. Treat - ment of Sfrp4- deficient mice with a soluble Bmp2 receptor (RAP-661) or with anti - bodies to sclerostin corrected the cortical-bone defect. CONCLUSIONS Our study showed that Pyle’s disease was caused by a deficiency of sFRP4, that cortical- bone and trabecular-bone homeostasis were governed by different mechanisms, and that sFRP4-mediated cross-regulation between Wnt and BMP signaling was critical for achieving proper cortical-bone thickness and stability. (Funded by the Swiss Na - tional Foundation and the National Institutes of Health.

Further insights in trichothiodistrophy: A clinical, microscopic, and ultrastructural study of 20 cases and literature review

Trichothiodistrophy (TTD) is a rare autosomal recessive condition that is characterized by a specific congenital hair shaft dysplasia caused by deficiency of sulfur associated with a wide spectrum of multisystem abnormalities. In this article, we study clinical, microscopic, and ultrastructural findings of 20 patients with TTD with the aim to add further insights regarding to this rare condition. Additionally, analyses of our results are compared with those extracted from the literature in order to enhance its comprehensibility. Materials and Methods: Twenty cases of TTD were included: 7 from Mexico and 14 from Spain. Clinical, microscopic, scanning electron microscopy (SEM) studies and X-ray microanalysis (XrMa) were carried out in all of them. Genetic studies were performed in all seven Mexican cases. Patients with xeroderma pigmentosum and xeroderma pigmentosum/TTD-complex were excluded. Results: Cuticular changes and longitudinal crests of the hair shaft were demonstrated. These crests were irregular, disorganized, following the hair longest axis. Hair shaft sulfur deficiency was disposed discontinuously and intermittently rather than uniformly. This severe decrease of sulfur contents was located close to the trichoschisis areas. Only five patients did not show related disturbances. Micro-dolichocephaly was observed in five cases and represented the most frequent facial dysmorphism found. It is also remarkable that all patients with urologic malformations also combined diverse neurologic disorders. Moreover, three Mexican sisters demonstrated the coexistence of scarce pubic vellus hair, developmental delay, onychodystrophy, and maxillar/mandibullar hypoplasia. Conclusions: TTD phenotype has greatly varied from very subtle forms to severe alterations such as neurologic abnormalities, blindness, lamellar ichthyosis and gonadal malformations. Herein, a multisystem study should be performed mandatorily in patients diagnosed with TTD