Global and Internal Diffusive Dynamics of Proteins in Solution Studied by Neutron Spectroscopy

Proteins are macromolecules naturally occurring in living cells and organisms, involved in a great number of processes essential for life, but they can be interesting not only from a biomedical perspective, but also for colloid physics, chemical engineering and nanotechnology, especially in the prospect of the smart production of self-assembling structures. In this thesis, the results of experiments carried out at the Institut Laue-Langevin, Grenoble, France, and at the Spallation Neutron Source at the Oak Ridge National Laboratory, Tennessee, USA, are presented. The picosecond to nanosecond (short-time) self-diffusion and internal dynamics of two model proteins in aqueous (D2O) solution is studied by neutron backscattering as a function of protein concentration, temperature and multivalent salt concentration. First, the concentration dependence of the translational diffusion of the antibody γ-globulin is rationalized in the context of colloid physics, while the protein internal dynamics is observed to slow down with increasing protein volume fraction. Second, temperature effects are studied on both the diffusion and the internal dynamics of the globular protein bovine serum albumin (BSA), below and above the denaturation temperature. A novel model is proposed to describe the dynamics of the protein side-chains, yielding a rather complete and consistent physical picture of the pico- to nanosecond dynamical changes occurring upon protein denaturation. Third, the change of the diffusion of BSA as a function of the concentration of the trivalent salt YCl3 is investigated, and a remarkably universal slowing down of the apparent diffusion coefficient of BSA molecules as a function of the number of cations per protein cs/cp in solution is found. The result is interpreted in terms of the theory of colloidal suspensions of patchy particles as a result of the semi-quantitative binding of Y3+ ions to specific sites on the protein surface leading to the formation of protein clusters with a cluster size distribution easily tunable by cs/cp

New frontiers of peer review

This news article introduces a new COST Action entitled PEERE (TD1306), which stands for New Frontiers of Peer Review (PEERE). PEERE is a trans-domain proposal which brings together researchers from various different disciplines and science stake-holders for the purpose of reviewing the process of peer review. PEERE officially began in May 2014 and will end in May 2018. Thirty-one countries, including Malta, are currently participating in the Action. In order to set the context in which this COST Action was initiated, we first look very briefly at the history of the process of peer review and various models of peer review currently in use. We then share what this COST Action hopes to achieve.peer-reviewe

ASOCIACIÓN ENTRE SÍNDROME DE SUEÑO INSUFICIENTE Y RENDIMIENTO ACADÉMICO EN INTERNOS DE MEDICINA HUMANA DE LA UNIVERSIDAD RICARDO PALMA EN EL PERIODO DICIEMBRE 2022 – FEBRERO 2023

Introducción: El síndrome de sueño insuficiente es un trastorno donde no se obtiene suficiente sueño nocturno, persistentemente, para mantener un adecuado estado de alerta. Mientras que el rendimiento académico es una medida de las capacidades del alumno. Objetivos: Determinar la asociación entre el Síndrome de sueño insuficiente y el rendimiento académico en internos de Medicina Humana de la universidad Ricardo Palma en el periodo diciembre 2022 – febrero 2023. Métodos: Estudio observacional transversal analítico, mediante la aplicación de encuestas virtuales realizadas a 167 internos de la facultad de Medicina Humana de la Universidad Ricardo Palma. En la selección de la muestra se aplicó el muestreo no probabilístico consecutivo. Para medir el Síndrome del Sueño insuficiente se aplicó el Índice de Calidad de Sueño de Pittsburgh y para el rendimiento académico el sistema de mérito de quintos superiores, agrupados como alto y bajo rendimiento. Resultados: De los 167 internos encuestados, el 59.9% fue de sexo masculino; mientras que la edad más prevalente fue el grupo de 25 años a más con un 64.1%. El 53.9% de internos encuestados tuvieron Síndrome de sueño insuficiente y el 44.3% obtuvieron rendimiento académico bajo. Además, de los que tenían 25 años a más se describe bajo rendimiento en el 67.3%. Finalmente, se encontró un mayor porcentaje con bajo rendimiento en quienes padecen de dicho síndrome siendo un 53.3%. Conclusión: La presencia del Síndrome de sueño insuficiente es un factor de riesgo para tener un bajo rendimiento académico

Effects of Curing on Photosensitive Resins in {SLA} Additive Manufacturing

Different mechanical properties characterise the materials of 3D printed components, depending on the specific additive manufacturing (AM) process, its parameters, and the post-treatment adopted. Specifically, stereolithography (SLA) uses a photopolymerisation technique that creates solid components through selective solidification. In this study, 72 specimens were 3D printed using 12 commercial-grade methacrylate resins and tested under uniaxial tensile loads. The resin specimens were evaluated before and after curing. The recommended cure temperature and time were followed for all materials. The stress-strain curves measured during the testing campaign were evaluated in terms of maximum tensile strength, Young’s modulus, ductility, resilience, and toughness. The results reveal that the curing process increases the material stiffness and resistance to tensile loads. However, it was found that the curing process generally reduces the plasticity of the resins, causing a more or less marked brittle behaviour. This represents a potential limitation to the use of SLA 3D printing for structural elements which require some plasticity to avoid dangerous sudden failures

Effects of Curing on Photosensitive Resins in {SLA} Additive Manufacturing

Different mechanical properties characterise the materials of 3D printed components, depending on the specific additive manufacturing (AM) process, its parameters, and the post-treatment adopted. Specifically, stereolithography (SLA) uses a photopolymerisation technique that creates solid components through selective solidification. In this study, 72 specimens were 3D printed using 12 commercial-grade methacrylate resins and tested under uniaxial tensile loads. The resin specimens were evaluated before and after curing. The recommended cure temperature and time were followed for all materials. The stress-strain curves measured during the testing campaign were evaluated in terms of maximum tensile strength, Young’s modulus, ductility, resilience, and toughness. The results reveal that the curing process increases the material stiffness and resistance to tensile loads. However, it was found that the curing process generally reduces the plasticity of the resins, causing a more or less marked brittle behaviour. This represents a potential limitation to the use of SLA 3D printing for structural elements which require some plasticity to avoid dangerous sudden failures

Effects of the Manufacturing Methods on the Mechanical Properties of a Medical-Grade Copolymer Poly(L-Lactide-co-D,L-Lactide) and Poly(L-Lactide-co-ɛ-Caprolactone) Blend

11openopenMariana Rodriguez Reinoso; Marco Civera; Vito Burgio; Annalisa Chiappone; Oliver Grimaldo Ruiz; Alessandra D'Anna; Carmela Riccio; Ignazio Roppolo; Alberto Frache; Paola Antonaci; Cecilia SuraceRODRIGUEZ REINOSO, Mariana; Civera, Marco; Burgio, Vito; Chiappone, Annalisa; GRIMALDO RUIZ, Oliver; D'Anna, Alessandra; Riccio, Carmela; Roppolo, Ignazio; Frache, Alberto; Antonaci, Paola; Surace, Cecili

Protein cluster formation in aqueous solution in the presence of multivalent metal ions -a light scattering study

The formation of protein clusters as precursors for crystallization and phase separation is of fundamental and practical interest in protein science. Using multivalent ions, the strengths of both long-range Coulomb repulsion and short-range attraction can be tuned in protein solutions, representing a wellcontrolled model system to study static and dynamic properties of clustering during the transition from a charge-stabilized to an aggregate regime. Here, we study compressibility, diffusion, and size of solutes by means of static (SLS) and dynamic light scattering (DLS) in solutions of bovine serum albumin (BSA) and YCl 3 . For this and comparable systems, an increasing screening and ultimately inversion of the protein surface charge induce a rich phase behavior including reentrant condensation, liquid-liquid phase separation and crystallization, which puts the cluster formation in the context of precursor formation and nucleation of liquid and crystalline phases. We find that, approaching the turbid aggregate regime with increasing salt concentration c s , the diffusion coefficients decrease and the scattered intensity increases by orders of magnitude, evidencing increasing correlation lengths likely associated with clustering. The combination of static and dynamic observations suggests the formation of BSA clusters with a size on the order of 100 nm. The global thermodynamic state seems to be stable over at least several hours. Surprisingly, results on collective diffusion and inverse compressibility from different protein concentrations can be rescaled into master curves as a function of c s /c*, where c* is the critical salt concentration of the transition to the turbid aggregate regime

Advances in Computational Social Science and Social Simulation

Aquesta conferència és la celebració conjunta de la "10th Artificial Economics Conference AE", la "10th Conference of the European Social Simulation Association ESSA" i la "1st Simulating the Past to Understand Human History SPUHH".Conferència organitzada pel Laboratory for Socio­-Historical Dynamics Simulation (LSDS-­UAB) de la Universitat Autònoma de Barcelona.Readers will find results of recent research on computational social science and social simulation economics, management, sociology,and history written by leading experts in the field. SOCIAL SIMULATION (former ESSA) conferences constitute annual events which serve as an international platform for the exchange of ideas and discussion of cutting edge research in the field of social simulations, both from the theoretical as well as applied perspective, and the 2014 edition benefits from the cross-fertilization of three different research communities into one single event. The volume consists of 122 articles, corresponding to most of the contributions to the conferences, in three different formats: short abstracts (presentation of work-in-progress research), posters (presentation of models and results), and full papers (presentation of social simulation research including results and discussion). The compilation is completed with indexing lists to help finding articles by title, author and thematic content. We are convinced that this book will serve interested readers as a useful compendium which presents in a nutshell the most recent advances at the frontiers of computational social sciences and social simulation researc

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified