342 research outputs found

    Photoresponsive Cellulose Nanocrystals Regular Paper

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    In this communication a method for the creation of fluorescent cellulose nanoparticles using click chemistry and subsequent photodimerization of the installed side-chains is demonstrated. In the first step, the primary hydroxyl groups on the surface of the CNCs were converted to carboxylic acids by using TEMPO-mediated hypohalite oxidation. The alkyne groups, essential for the click reaction, were introduced into the surface of TEMPO-oxidized CNCs via carbodiimide-mediated formation of an amide linkage between monomers carrying an amine functionality and carboxylic acid groups on the surface of the TEMPO-oxidized CNCs. Finally, the reaction of surface-modified TEMPO-oxidized cellulose nanocrystals and azido-bearing coumarin and anthracene monomers were carried out by means of a click chemistry, i.e., Copper(I))-catalyzed Azide-Alkyne Cycloaddition (CuAAC) to produce highly photo-responsive and fluorescent cellulose nanoparticles. Most significantly, the installed coumarin and/or anthracene side-chains were shown to undergo UV-induced [2+2] and [4+4] cycloaddition reactions, bringing and locking the cellulose nanocrystals together. This effort paves the way towards creating, cellulosic photo responsive nano-arrays with the potential of photo reversibility since these reactions are known to be reversible at varying wavelengths.Peer reviewe

    Photoresponsive Cellulose Nanocrystals

    Get PDF
    In this communication a method for the creation of fluorescent cellulose nanoparticles using click chemistry and subsequent photodimerization of the installed side‐ chains is demonstrated. In the first step, the primary hydroxyl groups on the surface of the CNCs were converted to carboxylic acids by using TEMPO‐mediated hypohalite oxidation. The alkyne groups, essential for the click reaction, were introduced into the surface of TEMPO‐ oxidized CNCs via carbodiimide‐mediated formation of an amide linkage between monomers carrying an amine functionality and carboxylic acid groups on the surface of the TEMPO‐oxidized CNCs. Finally, the reaction of surface‐modified TEMPO‐oxidized cellulose nanocrystals and azido‐bearing coumarin and anthracene monomers were carried out by means of a click chemistry, i.e., Copper(I)‐catalyzed Azide‐Alkyne Cycloaddition (CuAAC) to produce highly photo‐responsive and fluorescent cellulose nanoparticles. Most significantly, the installed coumarin and/or anthracene side‐chains were shown to undergo UV‐induced [2+2] and [4+4] cycloaddition reactions, bringing and locking the cellulose nanocrystals together. This effort paves the way towards creating, cellulosic photo responsive nano‐arrays with the potential of photo reversibility since these reactions are known to be reversible at varying wavelengths. 

    Photoresponsive Cellulose Nanocrystals

    Get PDF
    In this communication a method for the creation of fluorescent cellulose nanoparticles using click chemistry and subsequent photodimerization of the installed side‐ chains is demonstrated. In the first step, the primary hydroxyl groups on the surface of the CNCs were converted to carboxylic acids by using TEMPO‐mediated hypohalite oxidation. The alkyne groups, essential for the click reaction, were introduced into the surface of TEMPO‐ oxidized CNCs via carbodiimide‐mediated formation of an amide linkage between monomers carrying an amine functionality and carboxylic acid groups on the surface of the TEMPO‐oxidized CNCs. Finally, the reaction of surface‐modified TEMPO‐oxidized cellulose nanocrystals and azido‐bearing coumarin and anthracene monomers were carried out by means of a click chemistry, i.e., Copper(I)‐catalyzed Azide‐Alkyne Cycloaddition (CuAAC) to produce highly photo‐responsive and fluorescent cellulose nanoparticles. Most significantly, the installed coumarin and/or anthracene side‐chains were shown to undergo UV‐induced [2+2] and [4+4] cycloaddition reactions, bringing and locking the cellulose nanocrystals together. This effort paves the way towards creating, cellulosic photo responsive nano‐arrays with the potential of photo reversibility since these reactions are known to be reversible at varying wavelengths. 

    EVALUACIÓN NUTRICIONAL Y SOPORTE NUTRICIONAL POR VIA ENTERAL: NIVEL DE CONOCIMIENTOS DE ENFERMEROS DE UNIDADES DE TERAPIA INTENSIVA ADULTOS DE LOS HOSPITALES DE LA CIUDAD AUTÓNOMA DE BUENOS AIRES

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    Since the beginning of the 70s, studies have been published showing the benefits of teams of nutritional support to implement the Enteral Nutrition (EC) in an efficient way in patients that need it. Additionally, health care is a very important aspect in the management and running of the health system and it has direct implications in the quality of patients care. For this reason, nursing training is a relevant factor for the execution of general care and particularly for Nutritional Support. For Nutritional Support to be efficient and safe knowledge about Nutritional Evaluation, medical indications, management of specific techniques, implementation, monitoring and possible complications of Enteral Nutrition is needed.Desde principio de la década del ‘70 se publican estudios que demuestran las ventajas de equipos de soporte nutricional para implementar la Nutrición Enteral (NE) de manera eficiente en los pacientes que lo requieran, además la seguridad en la atención de la salud es un aspecto prioritario en la organización y funcionamiento del sistema de salud y posee implicancias directas en la calidad de atención de personas. En tal sentido la capacitación de enfermería es un factor de relevancia para la ejecución de cuidados en general y para el Soporte Nutricional (SN) en particular. Para que el SN sea efectivo y seguro son necesarios conocimientos sobre Evaluación Nutricional (EN), indicación, manejo de técnicas específicas, implementación, monitoreo y posibles complicaciones de la N

    ARTE E UTOPIA - O TEATRO DO BREAD & PUPPET

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    ABSTRACT: The Bread and Puppet Theatre was founded in New York in the 1960s and is certainly among the most important and long-lasting contributors to modern American theatre history. The troupe's Domestic Resurrection Circus emerged in the context of the countercultural goals of the 1960s and 70s and by the end of the "postmodern" 1990s, attracting audiences of over 30,000 spectators. This study is about Bread and Puppet Theatre's epic circuses and plays and asserts the need and urgency of critical relationship between theatre and utopian thought

    Musical Activities, Prosocial Behaviors, and Executive Function Skills of Kindergarten Children

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    Prosocial behaviors and executive function are staples of child development. Engagement in music has been associated with enhanced prosocial behaviors and executive function skills in children and youth. Yet, research concerning the role of formal music programs in the development of these important behaviors and skills remains elusive. The aim of this exploratory study was to investigate the role of a 5-week music program on prosocial behaviors (instrumental helping and sharing) and executive function skills (cognitive flexibility and working memory/inhibition control) of 103 kindergarten children from two public schools in a large urban center in the United States, serving predominantly Latinx children from underserved communities. Our data suggested that the short music program positively influenced children's cognitive flexibility, but not working memory, nor prosocial skills (sharing and helping). Findings are discussed in light of earlier studies, methodological issues, and limitations, and in relation to developmental and cultural issues surrounding child participants. Implications for future research and practice are outlined

    Structure and metal-binding properties of PA4063, a novel player in periplasmic zinc trafficking by Pseudomonas aeruginosa

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    The capability to obtain essential nutrients in hostile environments is a critical skill for pathogens. Under zinc-deficient conditions, Pseudomonas aeruginosa expresses a pool of metal homeostasis control systems that is complex compared with other Gram-negative bacteria and has only been partially characterized. Here, the structure and zinc-binding properties of the protein PA4063, the first component of the PA4063-PA4066 operon, are described. PA4063 has no homologs in other organisms and is characterized by the presence of two histidine-rich sequences. ITC titration detected two zinc-binding sites with micromolar affinity. Crystallographic characterization, performed both with and without zinc, revealed an α/β-sandwich structure that can be classified as a noncanonical ferredoxin-like fold since it differs in size and topology. The histidine-rich stretches located at the N-terminus and between β3 and β4 are disordered in the apo structure, but a few residues become structured in the presence of zinc, contributing to coordination in one of the two sites. The ability to bind two zinc ions at relatively low affinity, the absence of catalytic cavities and the presence of two histidine-rich loops are properties and structural features which suggest that PA4063 might play a role as a periplasmic zinc chaperone or as a concentration sensor useful for optimizing the response of the pathogen to zinc deficiency

    Recent Pharmacological Options in Type 2 Diabetes and Synergic Mechanism in Cardiovascular Disease

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    Diabetes Mellitus is a multifactorial disease with a critical impact worldwide. During prediabetes, the presence of various inflammatory cytokines and oxidative stress will lead to the pathogenesis of type 2 diabetes. Furthermore, insulin resistance and chronic hyperglycemia will lead to micro- and macrovascular complications (cardiovascular disease, heart failure, hypertension, chronic kidney disease, and atherosclerosis). The development through the years of pharmacological options allowed us to reduce the persistence of chronic hyperglycemia and reduce diabetic complications. This review aims to highlight the specific mechanisms with which the new treatments for type 2 diabetes reduce oxidative stress and insulin resistance and improve cardiovascular outcomes

    The Klingon batbugs : Morphological adaptations in the primitive bat bugs, Bucimex chilensis and Primicimex cavernis, including updated phylogeny of Cimicidae

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    The Cimicidae is a family of blood-dependent ectoparasites in which dispersion capacity is greatly associated with host movements. Bats are the ancestral and most prevalent hosts for cimicids. Cimicids have a worldwide distribution matching that of their hosts, but the global classification is incomplete, especially for species outside the most common Cimicidae taxa. In this study, we place a little-studied cimicid species, Bucimex chilensis, within a comprehensive molecular phylogeny of Cimicidae by sequencing the genomic regions of this and other closely related species. For this study, we collected B. chilensis females from Myotis chiloensis in Tierra del Fuego, 1300 km further south than previously known southernmost distribution boundary. We also sequenced COI regions from Primicimex cavernis, a species which together with B. chilensis comprise the entire subfamily Primiciminae. Using Bayesian posterior probability and maximum-likelihood approaches, we found that B. chilensis and P. cavernis clustered close to each other in the molecular analyses, receiving support from similar morphological features, agreeing with the morphology-based taxonomic placement of the two species within the subfamily Primiciminae. We also describe a previously unrecognized morphological adaptation of the tarsal structure, which allows the austral bat ectoparasite, B. chilensis, to cling on to the pelage of its known host, the Chilean myotis (Myotis chiloensis). Through a morphological study and behavioural observation, we elucidate how this tarsal structure operates, and we hypothesize that by clinging in the host pelage, B. chilensis is able to disperse effectively to new areas despite low host density. This is a unique feature shared by P. cavernis, the only other species in Primiciminae.The Cimicidae is a family of blood-dependent ectoparasites in which dispersion capacity is greatly associated with host movements. Bats are the ancestral and most prevalent hosts for cimicids. Cimicids have a worldwide distribution matching that of their hosts, but the global classification is incomplete, especially for species outside the most common Cimicidae taxa. In this study, we place a little-studied cimicid species, Bucimex chilensis, within a comprehensive molecular phylogeny of Cimicidae by sequencing the genomic regions of this and other closely related species. For this study, we collected B.chilensis females from Myotis chiloensis in Tierra del Fuego, 1,300km further south than previously known southernmost distribution boundary. We also sequenced COI regions from Primicimex cavernis, a species which together with B. chilensis comprise the entire subfamily Primiciminae. Using Bayesian posterior probability and maximum-likelihood approaches, we found that B.chilensis and P.cavernis clustered close to each other in the molecular analyses, receiving support from similar morphological features, agreeing with the morphology-based taxonomic placement of the two species within the subfamily Primiciminae. We also describe a previously unrecognized morphological adaptation of the tarsal structure, which allows the austral bat ectoparasite, B.chilensis, to cling on to the pelage of its known host, the Chilean myotis (Myotis chiloensis). Through a morphological study and behavioral observation, we elucidate how this tarsal structure operates, and we hypothesize that by clinging in the host pelage, B.chilensis is able to disperse effectively to new areas despite low host density. This is a unique feature shared by P.cavernis, the only other species in Primiciminae.Peer reviewe
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