A Complementary and Revised View on the N-Acylation of Chitosan with Hexanoyl Chloride

The modification of the biobased polymer chitosan is a broad and widely studied field. Herein, an insight into the hydrophobization of low-molecular-weight chitosan by substitution of amino functionalities with hexanoyl chloride is reported. Thereby, the influence of the pH of the reaction media was investigated. Further, methods for the determination of the degree of substitution based on 1H-NMR, FTIR, and potentiometric titration were compared and discussed regarding their accuracy and precision. 1H-NMR was the most accurate method, while FTIR and the potentiometric titration, though precise and reproducible, underlie the influence of complete protonation and solubility issues. Additionally, the impact of the pH variation during the synthesis on the properties of the samples was investigated by Cd2+ sorption experiments. The adjusted pH values during the synthesis and, therefore, the obtained degrees of substitution possessed a strong impact on the adsorption properties of the final material

Pueblos originarios, arqueología y patrimonio en el extremo sur de las cumbres calchaquíes

Este trabajo tiene por objetivo comunicar los avances del proyecto de socialización del patrimonio cultural que desarrollamos a partir de un acuerdo entre la Comunidad Indígena del pueblo Diaguita del valle de Tafí (Pcia. de Tucumán) y el Equipo de Arqueología del Sur de las Cumbres Calchaquíes (UNC-CONICET). Se pretende explicar el origen y trayectoria de esta experiencia, destacando las estrategias implementadas para proteger el patrimonio, incorporarlo a la experiencia práctica local y acercarlo a observadores remotos. El proceso de trabajo implicó tareas de carácter interdisciplinario que puso en diálogo diferentes conocimientos tanto de investigación como de saberes indígenas. Como resultado, se realizó un relevamiento arqueológico exhaustivo, se socializó el proyecto en la comunidad, se publicaron dos libros de difusión, se construyó un circuito comunitario en el sector Norte del cerro Ampuqcatao (valle de Tafí) y un museo de sitio virtual. Los circuitos son gestionados por la comunidad y fueron generados con la meta de incluirlos en la currícula de las escuelas de la zona, así como para hacer visible y reforzar la identidad e historia del Pueblo Diaguita.This paper communicates the progress of a project on cultural heritage socialization that we developed upon an agreement between Comunidad Indígena del pueblo Diaguita del valle de Tafí (Pcia. de Tucumán) and Equipo de Arqueología del Sur de las Cumbres Calchaquíes (UNC-CONICET). The aim is to explain the origin and trajectory of this experience, highlighting the strategies implemented to protect heritage, incorporate it into local practical experience and bring it closer to remote observers. The work process involved interdisciplinary tasks that brought into dialogue different knowledge from both research and indigenous knowledge. As a result, an exhaustive archaeological survey was carried out, the project was socialized in the community, two diffusion books were published, a community circuit was built in the northern sector of the Ampuqcatao mound (Tafí valley) with a virtual free access tour. The circuits are managed by the Community and were generated with the goal of including them in the curricula of the local schools, as well as making visible and reinforcing the identity and history of the Diaguita People.Fil: Carrasco, Dana Laura. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Cátedra de Prehistoria y Arqueología; ArgentinaFil: Chiavassa-Arias, Stefania. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Cátedra de Prehistoria y Arqueología; ArgentinaFil: Espeche, Ignacio. Universidad Nacional de Córdoba. Secretaria de Ciencia y Tecnología; ArgentinaFil: Montegu, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Físico- Matemáticas y Naturales; ArgentinaFil: Franco Salvi, Valeria Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades; ArgentinaFil: Salazar, Julián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades; Argentin

Black carbon in the Southern Andean snowpack

The Andean snowpack is an important source of water for many communities. As other snow-covered regions around the world, the Andes are sensitive to black carbon (BC) deposition from fossil fuel and biomass combustion. BC darkens the snow surface, reduces the albedo, and accelerates melting. Here, we report on measurements of the BC content conducted by using the meltwater filtration (MF) technique in snow samples collected across a transect of more than 2500 km from the mid-latitude Andes to the southern tip of South America. Addressing some of the key knowledge gaps regarding the effects of the BC deposition on the Andean snow, we identified BC-impacted areas, assessed the BC-related albedo reduction, and estimated the resulting snow losses. We found that BC concentrations in our samples generally ranged from 2 to 15 ng g-1, except for the nearly BC-free Patagonian Icefields and for the BC-impacted sites nearby Santiago (a metropolis of 6 million inhabitants). We estimate that the seasonal snowpack shrinking attributable to the BC deposition ranges from 4 mm water equivalent (w.e.) at relatively clean sites in Patagonia to 241 mm w.e. at heavily impacted sites close to Santiago. © 2022 The Author(s). Published by IOP Publishing Ltd

Black carbon in the Southern Andean snowpack

The Andean snowpack is an important source of water for many communities. As other snow-covered regions around the world, the Andes are sensitive to black carbon (BC) deposition from fossil fuel and biomass combustion. BC darkens the snow surface, reduces the albedo, and accelerates melting. Here, we report on measurements of the BC content conducted by using the meltwater filtration (MF) technique in snow samples collected across a transect of more than 2500 km from the mid-latitude Andes to the southern tip of South America. Addressing some of the key knowledge gaps regarding the effects of the BC deposition on the Andean snow, we identified BC-impacted areas, assessed the BC-related albedo reduction, and estimated the resulting snow losses. We found that BC concentrations in our samples generally ranged from 2 to 15 ng g-1, except for the nearly BC-free Patagonian Icefields and for the BC-impacted sites nearby Santiago (a metropolis of 6 million inhabitants). We estimate that the seasonal snowpack shrinking attributable to the BC deposition ranges from 4 mm water equivalent (w.e.) at relatively clean sites in Patagonia to 241 mm w.e. at heavily impacted sites close to Santiago. © 2022 The Author(s). Published by IOP Publishing Ltd

Black carbon footprint of human presence in Antarctica

Black carbon (BC) from fossil fuel and biomass combustion darkens the snow and makes it melt sooner. The BC footprint of research activities and tourism in Antarctica has likely increased as human presence in the continent has surged in recent decades. Here, we report on measurements of the BC concentration in snow samples from 28 sites across a transect of about 2,000 km from the northern tip of Antarctica (62°S) to the southern Ellsworth Mountains (79°S). Our surveys show that BC content in snow surrounding research facilities and popular shore tourist-landing sites is considerably above background levels measured elsewhere in the continent. The resulting radiative forcing is accelerating snow melting and shrinking the snowpack on BC-impacted areas on the Antarctic Peninsula and associated archipelagos by up to 23 mm water equivalent (w.e.) every summer

Towards interpreting recurrent neural networks through probabilistic abstraction

National Research Foundation (NRF) Singapore under its AI Singapore Programm

Investigaciones arqueológicas en la cuenca de Anfama, provincia de Tucumán

El valle de Anfama se emplaza en el faldeo oriental de las Cumbres Calchaquíes, al Noroeste de la provincia de Tucumán, entre los 1300 y 3000 msnm. Esta cuenca no ha sido objeto de investigaciones sistemáticas hasta la fecha, más allá de exploraciones tempranas de Adán Quiroga (1899) e intervenciones puntuales de Cremonte (1996). La ausencia de trabajos específicos previos para Anfama se corresponde con el rol marginal que en general han ocupado las vertientes orientales andinas en los estudios arqueológicos. Pese a ello, en los últimos años se han iniciado distintos proyectos que han generado datos e interpretaciones de primera mano, matizando y complejizando las visiones tradicionales (Caria y Míguez 2009; Corbalán 2008; Maldonado et al 2018; Míguez y Caria 2015). Dentro de esta serie de aportes, nuestro proyecto toma como eje central el estudio de la conformación y desintegración del mundo aldeano durante el primer milenio, la reactualización de las dinámicas sociales que le sucedieron en el segundo, y la articulación de Anfama dentro de lógicas regionales de mayor amplitud. Este trabajo presenta algunos avances de los estudios realizados e intenta proporcionar una caracterización arqueológica de la cuenca. Se propone un esquema cronológico constituido por cuatro bloques, que se relacionan con las modalidades de construcción del paisaje. A partir de la articulación entre tiempo, espacio y materialidad definimos tentativamente algunas dinámicas históricas.Fil: Salazar, Julián. Centro de Estudios Históricos "Profesor Carlos S. A. Segreti". Instituto de Estudios Históricos - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Históricos; ArgentinaFil: Molar Becchio, Rocío María. Centro de Estudios Históricos "Profesor Carlos S. A. Segreti". Instituto de Estudios Históricos - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Históricos; ArgentinaFil: Montegu, Juan Manuel. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Franco, Francisco. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vázquez Fiorani, Agustina. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Cátedra de Prehistoria y Arqueologia; ArgentinaFil: Moyano, Gonzalo. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Cátedra de Prehistoria y Arqueologia; ArgentinaFil: Chiavassa Arias, Stefanía. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Cátedra de Prehistoria y Arqueologia; ArgentinaFil: Carrasco, Dana Laura. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Cátedra de Prehistoria y Arqueologia; ArgentinaFil: Franco Salvi, Valeria Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Humanidades. Universidad Nacional de Córdoba. Instituto de Humanidades; ArgentinaXX Congreso Nacional de Arqueología ArgentinaCórdobaArgentinaUniversidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Instituto de Antropología de CórdobaUniversidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Departamento de AntropologíaUniversidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Museo de Antropologí

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London