Effect of chain stiffness on the morphology of polyelectrolyte complexes. A Monte Carlo simulation study

We have employed Monte Carlo simulations and a coarse grain model in order to analyze the final structure and morphology of complexes arising from the interaction between fully-flexible polycations and polyanions with different chain stiffness. Different morphologies, like globules, toroids and rods, are obtained depending on chain stiffness. It was observed that longer chains yield more frequently toroids than rods, as compared with shorter chains. However, the size of toroids does not depend entirely on the chain length. This suggests that the final structure of the toroids is highly dependent on the intrinsic rigidity of chain rather than on the electrostatic contributions. © 2010 Elsevier Ltd.Fil: Narambuena, Claudio Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Leiva, Ezequiel Pedro M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Chavez Paez, Martin. Universidad Autónoma de San Luis Potosí; MéxicoFil: Perez, Elias. Universidad Autónoma de San Luis Potosí; Méxic

Free energy of colloidal particles at the surface of sessile drops

The influence of finite system size on the free energy of a spherical particle floating at the surface of a sessile droplet is studied both analytically and numerically. In the special case that the contact angle at the substrate equals $\pi/2$ a capillary analogue of the method of images is applied in order to calculate small deformations of the droplet shape if an external force is applied to the particle. The type of boundary conditions for the droplet shape at the substrate determines the sign of the capillary monopole associated with the image particle. Therefore, the free energy of the particle, which is proportional to the interaction energy of the original particle with its image, can be of either sign, too. The analytic solutions, given by the Green's function of the capillary equation, are constructed such that the condition of the forces acting on the droplet being balanced and of the volume constraint are fulfilled. Besides the known phenomena of attraction of a particle to a free contact line and repulsion from a pinned one, we observe a local free energy minimum for the particle being located at the drop apex or at an intermediate angle, respectively. This peculiarity can be traced back to a non-monotonic behavior of the Green's function, which reflects the interplay between the deformations of the droplet shape and the volume constraint.Comment: 24 pages, 19 figure

Coordinated Defects in Hepatic Long Chain Fatty Acid Metabolism and Triglyceride Accumulation Contribute to Insulin Resistance in Non-Human Primates

Non-Alcoholic fatty liver disease (NAFLD) is characterized by accumulation of triglycerides (TG) in hepatocytes, which may also trigger cirrhosis. The mechanisms of NAFLD are not fully understood, but insulin resistance has been proposed as a key determinant

A collaboratively derived environmental research agenda for Galapagos

Galápagos is one of the most pristine archipelagos in the world and its conservation relies upon research and sensible management. In recent decades both the interest in, and the needs of, the islands have increased, yet the funds and capacity for necessary research have remained limited. It has become, therefore, increasingly important to identify areas of priority research to assist decision-making in Galápagos conservation. This study identified 50 questions considered priorities for future research and management. The exercise involved the collaboration of policy makers, practitioners and researchers from more than 30 different organisations. Initially, 360 people were consulted to generate 781 questions. An established process of preworkshop voting and three rounds to reduce and reword the questions, followed by a two-day workshop, was used to produce the final 50 questions. The most common issues raised by this list of questions were human population growth, climate change and the impact of invasive alien species. These results have already been used by a range of organisations and politicians and are expected to provide the basis for future research on the islands so that its sustainability may be enhanced. </jats:p

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Cambios ambientales, alimentación y sustento en una comunidad rural del manglar

Los manglares soportan altos niveles de biodiversidad y son la base de la subsistencia de comunidades costeras en el mundo. Este artículo explora la gama de productos marinos consumidos en una comunidad dependiente de manglares en Ecuador. En las entrevistas etnobiológicas, se nombraron 48 especies de peces, moluscos y crustáceos, de los cual, 85% son cosechados directamente por los moradores e intercambiados entre las casas. Los hallazgos también sugieren que, en los últimos 10 años, había cambios en los patrones de consumo que reflejan tendencias socio-ambientales más amplias, tales como una disminución de los recursos disponibles, el aumento poblacional y los conflictos con las flotas pesqueras industriales. Se necesita un análisis más sistemático para avanzar la comprensión sobre la relación entre subsistencia y cambio ambiental. Palabras Clave: Cambio ambiental; Ecuador; Etnobiología; Manglares; metodología etnográfica; pesca artesanal; seguridad alimentaria. Clasificación JEL: Q200. Abstract: Mangrove forests support high levels of biodiversity that form the basis of subsistence and livelihoods in coastal communities worldwide. This paper explores the range of marine products consumed by households in a mangrove-dependent community in Ecuador. In ethnobiological interviews, 48 species of fish, mollusks, and crustaceans were named, of which 85% are harvested directly by the inhabitants and exchanged between households. Findings also suggest that changes in consumption patterns in the past 10 years reflect broader socio-environmental trends, such as a decline in available resources, population growth, and conflicts with industrial fishing fleets. A more systematic and detailed analysis is needed to advance understanding about the relationship between subsistence and environmental change

Long-Term Outcomes of Intestinal and Multivisceral Transplantation at a Single Center in Argentina.

BACKGROUND:Intestinal failure (IF) patients received parenteral nutrition (PN) as the only available therapy until intestinal transplantation (ITx) evolved as an accepted treatment. The aim of this article is to report the long-term outcomes of a series of ITx performed in pediatric and adult patients at a single center 9 years after its creation.PATIENTS AND METHODS:This is a retrospective analysis of the ITx performed between May 2006 and January 2015. Diagnoses, pre-ITx mean time on PN, indications for ITx, time on the waiting list for types of ITx, mean total ischemia time, and warm ischemia time, time until PN discontinuation, incidence of acute and chronic rejection, and 5-year actuarial patient survival are reported.RESULTS:A total of 42 patients received ITx; 80% had short gut syndrome (SG); the mean time on PN was 1620 days. The main indication for ITx was lack of central venous access followed by intestinal failure-associated liver disease (IFALD) and catheter-related infectious complications. The mean time on the waiting list was 188 days (standard deviation, ±183 days). ITx were performed in 26 children and 14 adults. In all, 32 procedures were isolated ITx (IITX); 10 were multiorgan Tx (MOT; 3 combined, 7 multivisceral Tx (MVTx), 1 modified MVTx and 2 with kidney); 2 (4.7 %) were retransplantations: 1 IITx, 1 MVTx, and 5 including the right colon. Thirteen patients (31%) received abdominal rectus fascia. All procedures were performed by the same surgical team. Total ischemia time was 7:53 ± 2:04 hours, and warm ischemia time was 40.2 ± 10.5 minutes. The mean length of implanted intestine was 325 ± 63 cm. Bishop-Koop ileostomy was performed in 67% of cases. In all, 16 of 42 Tx required early reoperations. The overall mean follow-up time was 41 ± 35.6 months. The mean time to PN discontinuation after Tx was 68 days (P = .001). The total number of acute cellular rejection (ACR) episodes until the last follow-up was 83; the total number of grafts lost due to ACR was 4; and the total graft lost due to chronic rejection was 3. At the time of writing, the overall 5-year patient survival is 55% (65% for IITx vs 22% for MOT; P = .0001); 60% for pediatric recipients vs 47% for adults (P = NS); 64% when the indication for ITx was SG vs 25% for non-SG (P = .002).CONCLUSIONS:At this center, candidates with SG, in the absence of IFALD requiring IITx, showed the best long-term outcomes, independent of recipient age. A multidisciplinary approach is mandatory for the care of intestinal failure patients, to sustain a rehabilitation and transplantation program over time.Fil: Ramisch, D. Fundación Favaloro; ArgentinaFil: Rumbo, C. Fundación Favaloro; ArgentinaFil: Echevarria, C. Fundación Favaloro; ArgentinaFil: Moulin, L. Fundación Favaloro; ArgentinaFil: Niveyro, S. Fundación Favaloro; ArgentinaFil: Orce, G. Fundación Favaloro; ArgentinaFil: Crivelli, A. Fundación Favaloro; ArgentinaFil: Martinez, M. I.. Fundación Favaloro; ArgentinaFil: Chavez, L. Fundación Favaloro; ArgentinaFil: Paez, M.A.. Fundación Favaloro; ArgentinaFil: Trentadue, J.. Fundación Favaloro; ArgentinaFil: Klein, F.. Fundación Favaloro; ArgentinaFil: Fernandez, A.. Fundación Favaloro; ArgentinaFil: Solar Muñiz, H.. Fundación Favaloro; ArgentinaFil: Gondolesi, Gabriel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación Favaloro; Argentin