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BACKGROUND: Education influences brain health and dementia. However, its impact across regions, specifically Latin America (LA) and the United States (US), is unknown. METHODS: A total of 1412 participants comprising controls, patients with Alzheimer's disease (AD), and frontotemporal lobar degeneration (FTLD) from LA and the US were included. We studied the association of education with brain volume and functional connectivity while controlling for imaging quality and variability, age, sex, total intracranial volume (TIV), and recording type. RESULTS: Education influenced brain measures, explaining 24%-98% of the geographical differences. The educational disparities between LA and the US were associated with gray matter volume and connectivity variations, especially in LA and AD patients. Education emerged as a critical factor in classifying aging and dementia across regions. DISCUSSION: The results underscore the impact of education on brain structure and function in LA, highlighting the importance of incorporating educational factors into diagnosing, care, and prevention, and emphasizing the need for global diversity in research. HIGHLIGHTS: Lower education was linked to reduced brain volume and connectivity in healthy controls (HCs), Alzheimer's disease (AD), and frontotemporal lobar degeneration (FTLD). Latin American cohorts have lower educational levels compared to the those in the United States. Educational disparities majorly drive brain health differences between regions. Educational differences were significant in both conditions, but more in AD than FTLD. Education stands as a critical factor in classifying aging and dementia across regions.

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Activation of O2 by subnanometer metal clusters is a fundamental step in the reactivity and oxidation processes of single-cluster catalysts. In this work, we examine the adsorption and dissociation of O2 on RenPtm (n + m = 5) clusters supported on rutile TiO2(110) using DFT calculations. The adhesion energies of RenPtm clusters on the support are high, indicating significant stability of the supported clusters. Furthermore, the bimetallic Re-Pt clusters attach to the surface through the Re atoms. The oxygen molecule was adsorbed on three sites of the supported systems: the metal cluster, the surface, and the interface. At the metal cluster site, the O2 molecule binds strongly to RenPtm clusters, especially on the Re-rich clusters. O2 activation occurs by charge transfer from the metal atoms to the molecule. The dissociation of O2 on the RenPtm clusters is an exothermic process with low barriers. As a result, sub-nanometer Re-Pt clusters can be susceptible to oxidation. Similar results are obtained at the metal-support interface, where both the surface and cluster transfer charge to O2. To surface sites, molecular oxygen is adsorbed onto the Ti5c atoms with moderate adsorption energies. The polarons, which are produced by the interaction between the metal cluster and the surface, participate in the activation of the molecule. However, dissociating O2 in these sites is challenging due to the endothermic nature of the process and the high energy barriers involved. Our findings provide novel insights into the reactivity of supported clusters, specifically regarding the O2 activation by Re-Pt clusters on rutile TiO2(110).

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Chirality is a geometric property of matter that can be present at different scales, especially at the nanoscale. Here, we investigate the manifestation of chirality in electronic transport through a molecular junction. Spinless electronic transport through a chiral molecular junction is not enantiospecific. However, when a chiral metal cluster, C3-Au34, is attached to the source electrode, a different response is obtained in spinless electronic transport between R and L systems: this indicates the crucial role of chiral clusters in triggering enantiospecific spinless electronic transport. In contrast, when an achiral metal cluster, C3v-Au34, is attached, no change in conductance occurs between enantiomeric systems. Using the non-equilibrium green's function method, we characterized this phenomenon by calculating the transmission and conductance of spin-unpolarized electrons. Our theoretical results highlight the importance of metal clusters with specific sizes and chiral structures in electronic transport and support previously published experimental results that exhibited enantiospecific scanning tunneling measurements with intrinsically chiral tips.

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Los errores innatos de la inmunidad (EII), antes llamados inmunodeficiencias primarias (IDP), son un grupo heterogéneo de trastornos genéticos con defectos en uno o más componentes del sistema inmune. Los pacientes afectados por EII presentan aumentada susceptibilidad a microorganismos únicos o múltiples que se manifestará con infecciones recurrentes de diferente tipo y gravedad dependiendo del tipo de la localización del defecto. La prevención de infecciones es uno de los pilares fundamentales en el abordaje integral de los pacientes con EII. En este trabajo se resumen las conclusiones consensuadas en el Grupo de Trabajo de Inmunología Pediátrica de la Sociedad Argentina de Pediatría, sobre la base de la revisión de la evidencia disponible, respecto a los principios esenciales para el cuidado, la prevención de infecciones y la quimioprofilaxis en los errores innatos de la inmunidad para la orientación del pediatra y especialista dedicados al seguimiento de estas enfermedades.

Inborn errors of immunity, previously named primary immunodeficiency are a heterogeneous group of genetic defects of different components of the immune system. Patients present high susceptibility to an only or several microorganisms, developing recurrent infections; the severity is related to the specific genetic type of immunity defect. The main strategy on the management of these illness is the prevention of infections. These consensus guidelines made by the Pediatric Immunology Work Group of Sociedad Argentina de Pediatría, givese main approaches of infection prevention in order to provide a useful tool for all practitioners who are involved in the management of these patients, based on scientific evidence and broad consensus of a specialized panel expert.

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Inborn errors of immunity, previously named primary immunodeficiency are a heterogeneous group of genetic defects of different components of the immune system. Patients present high susceptibility to an only or several microorganisms, developing recurrent infections; the severity is related to the specific genetic type of immunity defect. The main strategy on the management of these illness is the prevention of infections. These consensus guidelines made by the Pediatric Immunology Work Group of Sociedad Argentina de Pediatría, givese main approaches of infection prevention in order to provide a useful tool for all practitioners who are involved in the management of these patients, based on scientific evidence and broad consensus of a specialized panel expert..

Los errores innatos de la inmunidad (EII), antes llamados inmunodeficiencias primarias (IDP), son un grupo heterogéneo de trastornos genéticos con defectos en uno o más componentes del sistema inmune. Los pacientes afectados por EII presentan aumentada susceptibilidad a microorganismos únicos o múltiples que se manifestará con infecciones recurrentes de diferente tipo y gravedad dependiendo del tipo de la localización del defecto. La prevención de infecciones es uno de los pilares fundamentales en el abordaje integral de los pacientes con EII. En este trabajo se resumen las conclusiones consensuadas en el Grupo de Trabajo de Inmunología Pediátrica de la Sociedad Argentina de Pediatría, sobre la base de la revisión de la evidencia disponible, respecto a los principios esenciales para el cuidado, la prevención de infecciones y la quimioprofilaxis en los errores innatos de la inmunidad para la orientación del pediatra y especialista dedicados al seguimiento de estas enfermedades.

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Background: Global brain health initiatives call for improving methods for the diagnosis of Alzheimer's disease (AD) and frontotemporal dementia (FTD) in underrepresented populations. However, diagnostic procedures in upper-middle-income countries (UMICs) and lower-middle income countries (LMICs), such as Latin American countries (LAC), face multiple challenges. These include the heterogeneity in diagnostic methods, lack of clinical harmonisation, and limited access to biomarkers. Methods: This cross-sectional observational study aimed to identify the best combination of predictors to discriminate between AD and FTD using demographic, clinical and cognitive data among 1794 participants [904 diagnosed with AD, 282 diagnosed with FTD, and 606 healthy controls (HCs)] collected in 11 clinical centres across five LAC (ReDLat cohort). Findings: A fully automated computational approach included classical statistical methods, support vector machine procedures, and machine learning techniques (random forest and sequential feature selection procedures). Results demonstrated an accurate classification of patients with AD and FTD and HCs. A machine learning model produced the best values to differentiate AD from FTD patients with an accuracy = 0.91. The top features included social cognition, neuropsychiatric symptoms, executive functioning performance, and cognitive screening; with secondary contributions from age, educational attainment, and sex. Interpretation: Results demonstrate that data-driven techniques applied in archival clinical datasets could enhance diagnostic procedures in regions with limited resources. These results also suggest specific fine-grained cognitive and behavioural measures may aid in the diagnosis of AD and FTD in LAC. Moreover, our results highlight an opportunity for harmonisation of clinical tools for dementia diagnosis in the region. Funding: This work was supported by the Multi-Partner Consortium to Expand Dementia Research in Latin America (ReDLat), funded by NIA/NIH (R01AG057234), Alzheimer's Association (SG-20-725707-ReDLat), Rainwater Foundation, Takeda (CW2680521), Global Brain Health Institute; as well as CONICET; FONCYT-PICT (2017-1818, 2017-1820); PIIECC, Facultad de Humanidades, Usach; Sistema General de Regalías de Colombia (BPIN2018000100059), Universidad del Valle (CI 5316); ANID/FONDECYT Regular (1210195, 1210176, 1210176); ANID/FONDAP (15150012); ANID/PIA/ANILLOS ACT210096; and Alzheimer's Association GBHI ALZ UK-22-865742.

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Cysteine-protected metal nanoparticles (NPs) have shown interesting physicochemical properties of potential utility in biomedical applications and in the understanding of protein folding. Herein, cysteine interaction with gold, silver, and copper NPs is characterized by Raman spectroscopy and density functional theory calculations to elucidate the molecular conformation and adsorption sites for each metal. The experimental analysis of Raman spectra upon adsorption with respect to free cysteine indicates that while the C-S bond and carboxyl group are similarly affected by adsorption on the three metal NPs, the amino group is sterically influenced by the electronegativity of each metal, causing a greater modification in the case of gold NPs. A theoretical approach that takes into consideration intermolecular interactions using two cysteine molecules is proposed using a S-metal-S interface motif anchored to the metal surface. These interactions generate the stabilization of an organo-metallic complex that combines gauche (PH) and anti (PC) rotameric conformers of cysteine on the surface of all three metals. Similarities between the calculated Raman spectra and experimental data confirm the thiol and carboxyl as adsorption groups for gold, silver, and copper NPs and suggest the formation of monomeric "staple motifs" that have been found in the protecting monolayer of atomic-precise thiolate-capped metal nanoclusters.

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Microplastics debris in the marine environment have been widely studied across the globe. Within these particles, the most abundant and prevalent type in the oceans are anthropogenic microfibers (MFs), although they have been historically overlooked mostly due to methodological constraints. MFs are currently considered omnipresent in natural environments, however, contrary to the Northern Hemisphere, data on their abundance and distribution in Southern Oceans ecosystems are still scarce, in particular for sub-Antarctic regions. Using Niskin bottles we've explored microfibers abundance and distribution in the water column (3-2450 m depth) at the Burdwood Bank (BB), a seamount located at the southern extreme of the Patagonian shelf, in the Southwestern Atlantic Ocean. The MFs detected from filtered water samples were photographed and measured using ImageJ software, to estimate length, width, and the projected surface area of each particle. Our results indicate that small pieces of fibers are widespread in the water column at the BB (mean of 17.4 ± 12.6 MFs.L-1), from which, 10.6 ± 5.3 MFs.L-1 were at the surface (3-10 m depth), 20 ± 9 MFs.L-1 in intermediate waters (41-97 m), 24.6 ± 17.3 MFs.L-1 in deeper waters (102-164 m), and 9.2 ± 5.3 MFs.L-1 within the slope break of the seamount. Approximately 76.1% of the MFs were composed of Polyethylene terephthalate, and the abundance was dominated by the size fraction from 0.1 to 0.3 mm of length. Given the high relative abundance of small and aged MFs, and the oceanographic complexity of the study area, we postulate that MFs are most likely transported to the BB via the Antarctic Circumpolar Current. Our findings imply that this sub-Antarctic protected ecosystem is highly exposed to microplastic pollution, and this threat could be spreading towards the highly productive waters, north of the study area.

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Las pacientes sanas portadoras de mutaciones patogénicas del gen BRCA1 tiene un riesgo muy elevado de desarrollar cáncer de mama y ovario, con cifras reportadas que ascienden a 84% y 59% respec- tivamente.¹ Esto motivó a implementar distintas medidas de segui- miento y de reducción de riesgo, como la mastectomía bilateral de reducción de riesgo (MRR) y la salpingo-ooforectomía de reducción de riesgo (SORR). Pero aún así, distintas experiencias publicadas re- fieren que en pacientes portadoras de mutacion BRCA1 sometidas a MRR, el riesgo subsiguiente de desarrollar un cáncer primario de mama puede llegar al 10%.2 Por otro lado, las técnicas de mastectomías en general han experi- mentado modificaciones en menos, conservando las estructuras te- gumentarias y el tejido adiposo que la recubre. Últimamente se ha expuesto que, con la guía de las imágenes, se puede resecar menos tejido aun, fundamentalmente en los contornos mamarios donde se observa tejido adiposo y nada (o muy escaso) tejido glandular.3 Esta recomendación hoy es empírica, ya que no hay evidencia de la segu- ridad oncológica de conservar estos tejidos

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PURPOSE: We present a physician survey of the impact of 21-gene Breast Recurrence Score test results on treatment decisions in clinical practice in Latin America. METHODS: This prospective survey enrolled consecutive patients at 14 sites in Argentina, Colombia, Mexico, and Peru who had routine 21-gene testing. Physician surveys captured patient and tumor characteristics and treatment decisions before and after 21-gene test results. The survey spanned the period before and after Trial Assigning Individualized Options for Treatment (TAILORx) results reported (June 2018). Overall net percent change in adjuvant chemotherapy recommendations was estimated, and asymptotic 95% CIs with continuity correction were calculated. The proportion with a change between pretest treatment recommendation and actual treatment received was calculated overall and by Recurrence Score groups per TAILORx. RESULTS: Between March 2015 and December 2019, the survey was completed for 647 patients; 20% were node-positive. The mean patient age was 54 years (24-85 years); 55% were postmenopausal; 17%, 63%, and 20% had grade 1, 2, and 3 tumors, respectively; and 30% had tumors > 2 cm. Recurrence Score (RS) results were as follows: 20% RS 0-10, 56% RS 11-25, and 24% RS 26-100. Overall, chemotherapy recommendations fell by a relative proportion of 39% (95% CI, 33.4 to 44.3) after 21-gene testing (33% decrease in node-negative and 55% decrease in node-positive). Among node-negative patients, the relative decrease in chemotherapy recommendations was 28% (95% CI, 18.9 to 39.5) before TAILORx and 36% (95% CI, 28.4 to 43.7) after. CONCLUSION: To our knowledge, this large survey of 21-gene test practice patterns was the first conducted in Latin America and showed the relevance of 21-gene testing in low- and medium-resource countries to minimize chemotherapy overuse and underuse in breast cancer. The results showed substantial reductions in chemotherapy use overall-especially after TAILORx reported-indicating the practice-changing potential of that study.

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Microplastics (MPs) have been identified in diverse marine invertebrates; however, there are few studies on limpets. This study aimed to evaluate and compare the presence of MPs in Nacella magellanica among sites of the Beagle Channel with different degree of anthropogenic influence. Intertidal limpets were sampled in three sites: Ushuaia Bay (UB) (inside Ushuaia city), a site with high anthropogenic influence owing to population growth, and fisheries, industrial and port activities; Ensenada Zaratiegui (EZ) and Playa Larga (PL) (west and east of Ushuaia city, respectively), both sites with a certain degree of environmental protection and low anthropogenic influence. MPs were isolated from the whole soft tissue of individuals by oxidative digestions with H2O2 (30%; 1:10 w/v). MPs occurrence was 100% in organisms from UB and EZ, whereas 90% in PL. Limpets from UB showed 10 ± 6.69 MPs/ind and 2.22 ± 0.78 MPs/g ww, while in PL and EZ there were 2.90 ± 2.02 MPs/ind and 0.96 ± 0.94 MPs/g ww; and 5.60 ± 2.59 MPs/ind and 2.41 ± 1.47 MPs/g ww, respectively. Fibres were the most abundant MPs type, followed by fragments and films. Fibres and films were identified as semi-synthetic cellulose and, although the polymer matrix of fragments was masked by copper phthalocyanine, one of them could be identified as polystyrene. As expected, the highest abundance of MPs was found in UB. However, a lower abundance of particles was detected in PL (downstream of UB) than in EZ (upstream of UB). This could be due to the influence of both the main current of the Beagle Channel and fluvial discharges, reducing the buoyancy of MPs. More studies are needed to understand the contribution of regional and local features to the accumulation of MPs in these environments and their interaction with the biota.

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The alkaloid caffeine and the amino acid arginine are present as secondary compounds in nectars of some flower species visited by pollinators. Each of these compounds affects honeybee appetitive behaviours by improving foraging activity and learning. While caffeine potentiates responses of mushroom body neurons involved in honeybee learning processes, arginine acts as precursor of nitric oxide, enhancing the protein synthesis involved in memory formation. Despite existing evidence on how these compounds affect honeybee cognitive ability individually, their combined effect on this is still unknown. We evaluated acquisition and memory retention in a classical olfactory conditioning procedure, in which the reward (sucrose solution) contained traces of caffeine, arginine or a mixture of the two. The results indicate that the presence of the single compounds and their most concentrated mixture increases bees' learning performance. However, memory retention, measured in the short and long term, increases significantly only in those treatments offering combinations of the two compounds in the reward. Additionally, the most concentrated mixture triggers a significant survival rate in the conditioned bees. Thus, some nectar compounds, when combined, show synergistic effects on cognitive ability and survival in an insect.

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Microplastics contamination is reported for the first time on Mytilus chilensis from Ushuaia Bay, one of the most remote areas of South America. Our results demonstrate the occurrence of microplastics in all samples, with an average of 8.6 ±â€¯3.53 items per individual. Fibers and fragments were the most abundant, with a percentage of 77.91 and 17.44%, respectively. The average length of the fibers was 742.3 ±â€¯702.1 µm, while the average cross-sectional area of fragments was 1944.80 ±â€¯960.94 µm2. The polymers identified were polyamides, semi-synthetic cellulosic materials, and PVC copolymers. The number of microplastics per individual was greater than those reported in even more populated regions. Probably, the modifications included in the technique led to optimize the extraction of MPs, reflecting the detection of a greater number of particles. M. chilensis could play a role in an extensive evaluation of MPs in the Ushuaia Bay, providing information on the interaction of MPs and biota.

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Antecedentes: dada la mayor disponibilidad de estudios genéticos, en los últimos años se incrementaron significativamente las mastectomías de reducción de riesgo (MRR). Objetivo: analizar la experiencia institucional en MRR. Material y métodos: se tuvieron en cuenta las pacientes sanas sometidas a MRR bilateral simultánea y también las pacientes con antecedentes de cáncer de mama que luego fueron sometidas a MRR contralateral. No fueron tenidas en cuenta las mastectomías realizadas como tratamiento actual de un cáncer, pero sí la mastectomía contralateral. Resultados: se realizaron 70 MRR en 49 pacientes que cumplían con los criterios de inclusión para el análisis. La edad promedio fue de 44 años (rango 34-64). En 60 casos se conservó el complejo areola-pezón. En 50 casos, la reconstrucción mamaria fue con implante protésico directo. En 57 pacientes la incisión fue radiada en cuadrante superoexterno. En 57 casos no presentaron complicaciones y, de las restantessolo en 1 (1,4%) se perdió el implante. En un solo caso se detectó un carcinoma de mama oculto, y, en la evolución, una paciente desarrolló un carcinoma pequeño en la mama operada. Conclusión: la MRR es una alternativa válida y segura en mujeres con alto riesgo de cáncer de mama, pues logra disminuir en forma significativa la probabilidad de padecer la enfermedad, con buenos resultados estéticos y alto nivel de satisfacción.

Background: The number of risk-reducing mastectomies (RRM) has increased over the past years as genetic testing has become more readily available. Objective: The aim of this study was to analyze the experience of our institution with RRM. Material and methods: The analysis included healthy patients undergoing simultaneous bilateral RRM and those with a history of breast cancer who underwent contralateral RRM. Patients with mastectomies performed as treatment of breast cancer were not considered, but those with contralateral mastectomies were included. Results: Seventy RRM were performed in 49 patients who fulfilled the inclusion criteria for the analysis. Mean age was 44 years (range: 34-64). The nipple-areola complex was preserved in 60 cases. In 50 cases, a prosthesis was implanted for breast reconstruction during the same procedure. The breast was approach through a radial incision in the upper outer quadrant in 57 patients. Fifty-seven patients did not present complications, and in the rest of the cases the implant failed in only one (1.4%) case. An occult breast cancer was detected in only one patient. During follow-up, one patient developed a small carcinoma in the operated breast. Conclusion: RRM is a valid and safe option for women at high risk for breast cancer, since it significantly reduces the probability of developing the disease, with good aesthetic results and a high level of patient satisfaction.

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Objetivo El objetivo del presente trabajo es analizar la evolución de las pacientes sometidas a reconstrucción mamaria inmediata con implantes asistidos con mallas de poliglactina 910. Material y método Se colocaron 135 mallas de poliglactina en 100 pacientes. En 35 pacientes, la reconstrucción mamaria fue bilateral y en 65 casos fue unilateral. En 71 casos (52,6%), se realizó con implante mamario directo y en 64 (47,4%) con expansor tisular transitorio seguido de reemplazo por prótesis definitiva. En 87 casos (64,4%), la herida cutánea no estaba en contacto con la malla, y en 48 (35,6%) la malla estaba en contacto con el tejido celular subcutáneo y la herida quirúrgica. 18 reconstrucciones mamarias fueron realizadas en tejidos previamente irradiados mientras que 7 pacientes fueron irradiadas luego de la mastectomía. Resultados Se registraron 32 complicaciones en 25 pacientes. En 21 pacientes (84%), se requirió corrección quirúrgica. En total, fueron 7 implantes perdidos (5,2%), 5 de los cuales tenían antecedentes de radioterapia previa. Conclusiones Pudimos constatar la buena adaptación de las mallas de poliglactina a la técnica quirúrgica, permitiendo obtener buenos resultados iniciales con una adecuada tasa de complicaciones. Las pacientes con tratamientos radiantes son los más expuestos a complicaciones y pérdidas del implante

Objective To assess the outcomes in patients undergoing implant-based immediate breast reconstruction assisted with polyglactin 910 mesh. Materials and method 135 polyglactin meshes were placed in 100 patients. In 35 patients, breast reconstruction was bilateral and in 65 cases it was unilateral. The reconstruction was performed in 71 cases (52.6%) with a definitive breast implant and in 64 cases (47.4%) with a tissue expander followed later by its replacement for a definitive prosthesis. In 87 cases (64.4%) the wound was not in contact with the mesh, and in 48 (35.6%) the mesh was in contact with the subcutaneous cellular tissue and the surgical wound. 18 breast reconstructions were performed on previously irradiated tissues while 7 patients received postmastectomy radiotherapy. Results There were 32 complications in 25 patients. In 21 cases (84%) there was some surgical procedure required. There were 7 implants lost (5.2%), 5 of which belonged to patients that had previous radiotherapy history. Conclusions We acknowledge the good adaptation of the polyglactin meshes to the surgical technique, allowing to obtain good results with low complications rate. Patients with radiotherapy are the most exposed to complications and implant losses

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Controlling Ce4+ to Ce3+ electronic reducibility in a rare-earth binary oxide such as CeO2 has enormous applications in heterogeneous catalysis, where a profound understanding of reactivity and selectivity at the atomic level is yet to be reached. Thus, in this work we report an extensive DFT-based Basin Hopping global optimization study to find the most stable bimetallic Pt-Cu clusters supported on the CeO2(111) oxide surface, involving up to 5 atoms in size for all compositions. Our PBE+U global optimization calculations indicate a preference for Pt-Cu clusters to adopt 2D planar geometries parallel to the oxide surface, due to the formation of strong metal bonds to oxygen surface sites and charge transfer effects. The calculated adsorption energy values (Eads) for both mono- and bimetallic systems are of the order of 1.79 up to 4.07 eV, implying a strong metal cluster interaction with the oxide surface. Our calculations indicate that at such sub-nanometer sizes, the number of Ce4+ surface atoms reduced to Ce3+ cations is mediated by the amount of Cu atoms within the cluster, reaching a maximum of three Ce3+ for a supported Cu5 cluster. Our computational results have critical implications on the continuous understanding of the strong metal-support interactions over reducible oxides such as CeO2, as well as the advancement of frontier research areas such as heterogeneous single-atom catalysts (SAC) and single-cluster catalysts (SCC).

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Introducción: Para cumplimentar la misión de la universidad cubana, preparar al profesional para su desempeño exitoso en la sociedad, es imprescindible la integración dialéctica de los procesos sustantivos: académico, laboral y extensionista con la investigación. Objetivo: Elaborar acciones pedagógicas para perfeccionar la actividad científico-estudiantil. Métodos: Investigación en el campo de la educación médica con los estudiantes de la Facultad de Estomatología "Raúl González Sánchez" en el curso 2016- 2017. Se utilizaron métodos teóricos: el análisis y síntesis de la bibliografía consultada y la revisión documental. También se realizaron entrevistas grupales a estudiantes y profesores deldepartamento de Informática, una encuesta a profesores de otros departamentos. Los datos fueron procesados utilizando la estadística descriptiva y se presentaron en números absolutos y porcientos. Resultados: El 79,6 por ciento y 96,8 por ciento de los estudiantes expresó que no está preparado para investigar y poca disponibilidad de computadoras y acceso a Internet respectivamente, 91,3 por ciento manifestaron falta de motivación. Entre las acciones pedagógicas propuestas estuvieron la implementación de cursos sobre en el currículo optativo/electivo, la incorporación de estudiantes a proyectos de investigación de los profesores y creación del Grupo Científico Estudiantil (GCE) de la facultad. Conclusiones: La actividad científica-estudiantil no ha alcanzado los resultados esperados. Las acciones pedagógicas que se proponen, con el fin de perfeccionar los resultados de la actividad científica-estudiantil, permiten a los profesores y directivos de la facultad, contar con una guía actualizada para orientar el trabajo hacia el logro de mejores resultados de la actividad científica estudiantil en la institución(AU)

Introduction: In order to complete the mission of the Cuban university and to prepare the professionals for their successful performance in the society, it is essential the dialectical integration of the substantive processes (academic, work-related and university outreach) with research. Objective: To elaborate pedagogical actions to perfect the student scientific activity. Methods: Research carried out in the field of medical education with the students of Raúl González Sánchez Dental School, during the academic year 2016-2017. The theoretical methods include analysis and synthesis of the consulted bibliography and document review. Group interviews were also conducted on students and professors from the IT department, together with a survey on professors from other departments. The data were processed using descriptive statistics and presented in absolute and percentage numbers. Results: 79.6 por ciento and 96.8 por ciento of the students expressed that they are not ready to investigate and that there is scarce availability of computers and Internet access, respectively. 91.3 por ciento noted lack of motivation. The proposed pedagogical actions include the implementation of courses on the optional and elective curricula, the incorporation of students to research projects by the professors, and the creation of the Student Scientific Group (GCE) in the School. Conclusions: Student scientific activity has not achieved the expected results. The pedagogical actions proposed for improving the outcome of student scientific activity allow the professors and directors of the School to have updated guidelines for working towards the achievement of better outcome as part of the student scientific activity in the institution(AU)

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Transition and noble metal clusters have proven to be critical novel materials, potentially offering major advantages over conventional catalysts in a range of value-added catalytic processess such as carbon dioxide transformation to methanol. In this work, a systematic computational study of CO2 adsorption on gas-phase Cu4-xPtx (x = 0-4) clusters is performed. An exhaustive potential energy surface exploration is initially performed using our recent density functional theory basin-hopping global optimization implementation. Ground-state and low-lying energy isomers are identified for Cu4-xPtx clusters. Secondly, a CO2 molecule adsorption process is analyzed on the ground-state Cu4-xPtx configurations, as a function of cluster composition. Our results show that the gas-phase linear CO2 molecule is deformed upon adsorption, with its bend angle varying from about 132° to 139°. Cu4-xPtx cluster geometries remain unchanged after CO2 adsorption, with the exception of Cu3Pt1 and Pt4 clusters. For these particular cases, a structural conversion between the ground-state geometry and the corresponding first isomer configurations is found to be assisted by the CO2 adsorption. For all clusters, the energy barriers between the ground-state and first isomer structures are explored. Our calculated CO2 adsorption energies are found to be larger for Pt-rich clusters, exhibiting a volcano-type plot. The overall effect of a hybrid functional including dispersion forces is also discussed.

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Transition metal particles dispersed on oxide supports are used as heterogeneous catalysts in numerous applications. One example is platinum clusters supported on ceria which is used in automotive catalysis. Although control at the nm-scale is desirable to open new technological possibilities, there is limited knowledge both experimentally and theoretically regarding the geometrical structure and stability of sub-nanometer platinum clusters supported on ceria. Here we report a systematic, Density Functional Theory (DFT) study on the growth trends of CeO2(111) supported PtN clusters (N = 1-10). Using a global optimization methodology as a guidance tool to locate putative global minima, our results show a clear preference for 2D planar structures up to size Pt8. It is followed by a structural transition to 3D configurations at larger sizes. This remarkable trend is explained by the subtle competition between the formation of strong Pt-O bonds and the cluster internal Pt-Pt bonds. Our calculations show that the reducibility of CeO2(111) provides a mechanism to anchor PtN clusters where they become oxidized in a two-way charge transfer mechanism: (a) an oxidation process, where Osurface atoms withdraw charge from Pt atoms forming Pt-O bonds, (b) surface Ce4+ atoms are reduced, leading to Ce3+. The active role of the CeO2(111) support in modifying the structural and eventually the chemical properties of sub-nanometer PtN clusters is computationally demonstrated.

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BACKGROUND: The total number of known three-dimensional protein structures is rapidly increasing. Consequently, the need for fast structural search against complete databases without a significant loss of accuracy is increasingly demanding. Recently, TopSearch, an ultra-fast method for finding rigid structural relationships between a query structure and the complete Protein Data Bank (PDB), at the multi-chain level, has been released. However, comparable accurate flexible structural aligners to perform efficient whole database searches of multi-domain proteins are not yet available. The availability of such a tool is critical for a sustainable boosting of biological discovery. RESULTS: Here we report on the development of a new method for the fast and flexible comparison of protein structure chains. The method relies on the calculation of 2D matrices containing a description of the three-dimensional arrangement of secondary structure elements (angles and distances). The comparison involves the matching of an ensemble of substructures through a nested-two-steps dynamic programming algorithm. The unique features of this new approach are the integration and trade-off balancing of the following: 1) speed, 2) accuracy and 3) global and semiglobal flexible structure alignment by integration of local substructure matching. The comparison, and matching with competitive accuracy, of one medium sized (250-aa) query structure against the complete PDB database (216,322 protein chains) takes about 8 min using an average desktop computer. The method is at least 2-3 orders of magnitude faster than other tested tools with similar accuracy. We validate the performance of the method for fold and superfamily assignment in a large benchmark set of protein structures. We finally provide a series of examples to illustrate the usefulness of this method and its application in biological discovery. CONCLUSIONS: The method is able to detect partial structure matching, rigid body shifts, conformational changes and tolerates substantial structural variation arising from insertions, deletions and sequence divergence, as well as structural convergence of unrelated proteins.

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