1,627 research outputs found

    N-Heterocyclic Carbene Gold Complexes Active in Hydroamination and Hydration of Alkynes

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    Until the year 2000, gold compounds were considered catalytically inert. Subsequently, it was found that they are able to promote the nucleophilic attack on unsaturated substrates by forming an Au-pi-system. The main limitation in the use of these catalytic systems is the ease with which they decompose, which is avoided by stabilization with an ancillary ligand. N-heterocyclic carbenes (NHCs), having interesting sigma-donor capacities, are able to stabilize the gold complexes (Au (I/III) NHC), favoring the exploration of their catalytic activity. This review reports the state of the art (years 2007-2022) in the nucleophilic addition of amines (hydroamination) and water (hydration) to the terminal and internal alkynes catalyzed by N-heterocyclic carbene gold (I/III) complexes. These reactions are particularly interesting both because they are environmentally sustainable and because they lead to the production of important intermediates in the chemical and pharmaceutical industry. In fact, they have an atom economy of 100%, and lead to the formation of imines and enamines, as well as the formation of ketones and enols, all important scaffolds in the synthesis of bioactive molecules, drugs, heterocycles, polymers, and bulk and fine chemicals

    Biomasa individual y poblacional de arbustos dominantes en estepas patagĂłnicas pastoreadas

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    269-279Estimating aboveground biomass of vegetation is essential for population, community and ecosystem studies. In systems dominated or co-dominated by woody species, biomass estimation is difficult, and rapid and non-destructive methods are needed. In this study, we describe biomass distribution in different components (i.e., wood, leaves) and how this changes with shrub size for the three dominant species of shrubs in the Occidental District of the Patagonian steppe. We also describe the population size structure of the three species in grazed fields and estimate their contribution to total abundance and biomass through a non-destructive method. We developed allometric equations to estimate aboveground biomass components of individual shrubs from structural descriptors (i.e., diameter and height of the crown), sampling individual plants of different sizes. The variable that best predicted biomass of the three species was the sum of the height and the average diameter of the crown (calculated with the largest diameter and its perpendicular). Allometric models for each species explained more than 83 percent of the variability of individual aboveground biomass. At the individual level, species had different proportions of wood, leaves and specific wood weight. Increasing shrub size was accompanied by changes in the proportion of leaves to wood, and in some cases, the percentage of dead crown. At the population level, the three species differed in size distribution in moderately grazed fields. Development of allometric models from a population perspective is important to study demographic processes that drive community and ecosystem responses to environmental and land-use changes

    Ab initio parametrised model of strain-dependent solubility of H in alpha-iron

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    The calculated effects of interstitial hydrogen on the elastic properties of alpha-iron from our earlier work are used to describe the H interactions with homogeneous strain fields using ab initio methods. In particular we calculate the H solublility in Fe subject to hydrostatic, uniaxial, and shear strain. For comparison, these interactions are parametrised successfully using a simple model with parameters entirely derived from ab initio methods. The results are used to predict the solubility of H in spatially-varying elastic strain fields, representative of realistic dislocations outside their core. We find a strong directional dependence of the H-dislocation interaction, leading to strong attraction of H by the axial strain components of edge dislocations and by screw dislocations oriented along the critical slip direction. We further find a H concentration enhancement around dislocation cores, consistent with experimental observations.Comment: part 2/2 from splitting of 1009.3784 (first part was 1102.0187), minor changes from previous version

    ORAL LESIONS DUE TO ACINETOBACTER BAUMANNII INFECTION IN A PATIENT AFFECTED BY AUTOIMMUNE HEMOLYTIC ANEMIA (AIHA): FIRST CLINICAL REPORT

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    Aim. Acinetobacter Baumannii (coming from the Greek “akinetos,” i.e. non-motile) is an opportunistic bacterial pathogen primarily associated with hospital-acquired infections. Commonly associated with aquatic environments, A. Baumannii easily contaminates the surrounding environment and it colonizes acute ill patients in which can survive for several days. Generally, A. Baumannii is able to damage mucous membranes or exposed skin after accident or injury; it may be responsible of many diseases such as pneumonia, bacteremia, meningitis, urinary tract infections, peritonitis and infections of skin and soft tissues. Tissues infected by A. Baumannii initially present “orange peel” appearance followed by sandpaper-like presentation, when there is a disruption, hemorrhagic bullae can be seen with a visible necrotizing process followed by bacteremia. Current therapy is based on intravenous administration of tigecycline 100-200 mg (first dose) and 50-100 mg every 12 h for up to 14 days, unless complications. If untreated, this infection can lead to septicemia and death. The mortality rate of this infection is high, especially in case of bacteremia (52%) and pneumonia (23–73%). A. Baumannii is resistant to many drugs and represents an important nosocomial pathogen that particularly infects critically ill patients. At the best of our knowledge, no case of oral infection has been reported. to present the first one case characterized by oral soft tissue infection due to A. Baumannii responsive to imipenem. Materials and methods. a 78 years male was hospitalized in August of 2013 at the Hematology unit of the A.O.U.P. “P. Giaccone” of Palermo with a diagnosis of autoimmune hemolytic anemia (AIHA). He was treated per os with corticosteroids (Prednisone) and immunosuppressants (Rituximab and Cyclophosphamide), also IVIG (Intra Venous Immuno-Globulin) was administreted. In November 2013, the patient was treated with piperacillin IV (Tazocin) for treating an urinary tract infection; four days after, multiple oral ulcerative bullous lesions on the lingual and buccal mucosa and crusted lesions on the lip vermilion appeared, associated with intense pain. An oral swab for bacteria research was carried out; topical therapy (chlorhexidine rinses and hyaluronic acid gel) has been prescribed and piperacillin therapy was stopped. Oral swab outcome resulted positive for A. Baumannii and Enterococcus Faecalis, both sensitive only to imipenem, that was administrated (500 mg IV every 8h) for 10 days. The patient was immediately isolated in a single room for preventing and controlling the spread of A. Baumannii. Results. From diagnosis, every 3 days clinical examination of the oral cavity was performed, revealing the progressive regression within thirty days until complete healing without leaving scars. After, a second oral swab confirmed the absence of any bacteria. Conclusions. The World Health Organization has recently identified antimicrobial resistance as one of the three most important problems facing human health and among the most common and serious pathogens, including A. Baumannii. It is an emerging potentially drug-resistant micro-organism and its isolation must alert physicians to carry on all preventive measures for avoiding contamination of other patients, especially those immunosuppressed, at risk for severe persistent infections or death. This precaution should be continued for all the duration of hospitalization and until the negativization of culture samples was obtained. It is important that physicians and dentists recognize suspicious lesions in unusual locations, such as oral mucosa, in absence of other known etiological factors in a timely manner before the diffusion among other patients in order to avoid the spread of a nosocomial outbreak

    Physical Activity Measures in the Healthy Communities Study

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    The risk of obesity is reduced when youth engage in recommended levels of physical activity (PA). For that reason, public health organizations in the U.S. have encouraged communities to implement programs and policies designed to increase PA in youth, and many communities have taken on that challenge. However, the long-term effects of those programs and policies on obesity are largely unknown. The Healthy Communities Study is a large-scale observational study of U.S. communities that is examining the characteristics of programs and policies designed to promote healthy behaviors (e.g., increase PA and improve diet) and determining their association with obesity-related outcomes. The purpose of this paper is to describe the methods used to measure PA in children and the personal and community factors that may influence it. The study used both self-reported and objective measures of PA, and measured personal, family, and home influences on PA via three constructs: (1) PA self-schema; (2) parental support; and (3) parental rules regarding PA. Neighborhood and community factors related to PA were assessed using three measures: (1) child perceptions of the neighborhood environment; (2) availability of PA equipment; and (3) attributes of the child’s street segment via direct observation. School influences on children’s PA were assessed via three constructs: (1) school PA policies; (2) child perceptions of the school PA environment; and (3) school outdoor PA environment. These measures will enable examination of the associations between characteristics of community PA programs and policies and obesity-related outcomes in children and youth

    Effect of smoking status on total energy expenditure

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    Individuals who smoke generally have a lower body mass index (BMI) than nonsmokers. The relative roles of energy expenditure and energy intake in maintaining the lower BMI, however, remain controversial. We tested the hypothesis that current smokers have higher total energy expenditure than never smokers in 308 adults aged 40-69 years old of which 47 were current smokers. Energy expenditure was measured by doubly labeled water during a two week period in which the subjects lived at home and performed their normal activities. Smoking status was determined by questionnaire. There were no significant differences in mean BMI (mean ± SD) between smokers and never smokers for either males (27.8+5.1 kg/m2 vs. 27.5+4.0 kg/m2) or females (26.5+5.3 kg/m2 vs. 28.1+6.6 kg/m2), although the difference in females was of similar magnitude to previous reports. Similarly, total energy expenditure of male smokers (3069+764 kcal/d) was not significantly different from that of never smokers (2854+468 kcal/d), and that of female smokers (2266+387 kcal/d) was not different from that of never smokers (2330+415 kcal/d). These findings did not change after adjustment for age, fat-free mass and self-reported physical activity. Using doubly labeled water, we found no evidence of increased energy expenditure among smokers, however, it should be noted that BMI differences in this cohort also did not differ by smoking status

    effects of an antioxidant protective topical formulation on eye exposed to ultraviolet irradiation a study in rabbit animal model

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    Ultraviolet-radiation exerts a well-known role in the development of various ocular diseases and may contribute to the progress of age-related macular degeneration. Therefore, the use of compounds able to protect the eyes from UV-induced cellular damage is challenging. The aim of this study has been to test the protective effects of an antioxidant topical formulation against UV-induced damage in rabbit eyes. Twelve male rabbits were used. Animals were divided into 4 groups of 3 animals each. Control group (CG) did not receive any irradiation and/or eye drop. The other three experimental groups were treated as follows: the first group received only UVR irradiation for 30 min, without eye drop supplementation (Irradiation group, IG), the second (G30) and the third (G60) groups received UV irradiation for 30' and 60', respectively, and eye drop supplementation (riboflavin, d-α-tocopheryl polyethylene glycol, proline, glycine, lysine and leucine solution) every 15 min for three hours. In the IG group a significant increase of oxidized glutathione (GSSG) and hydrogen peroxide (H2O2) was recorded in the aqueous humor, whereas ascorbic acid levels were significantly lower when compared to control eyes. In the groups exposed to UVR rays for 30 min, and treated with the topical antioxidant formulation, the GSSG, H2O2 and ascorbic acid levels were similar to those recorded in controls, whereas in the G60 group the three markers significantly differ from control group. In the lens, a significant decrease of alpha tocopherol and total antioxidant capacity (TAC) was recorded in IG-animals as compared to control group, whereas malondialdehyde (MDA) levels were significantly higher in UV-induced eye than in control eyes. In the G30 groups the alpha tocopherol, MDA and TAC levels do not significantly differ from those recorded in controls, whereas in the G60 group these three markers significantly differ from control group. Present findings demonstrate that topical treatment with the antioxidant formulation used herein protects ocular structures from oxidative stress induced by UV exposure in in vivo animal model

    Effects of an antioxidant protective topical formulation on eye exposed to ultraviolet-irradiation: A study in rabbit animal model

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    Ultraviolet-radiation exerts a well-known role in the development of various ocular diseases and may contribute to the progress of age-related macular degeneration. Therefore, the use of compounds able to protect the eyes from UV-induced cellular damage is challenging. The aim of this study has been to test the protective effects of an antioxidant topical formulation against UV-induced damage in rabbit eyes. Twelve male rabbits were used. Animals were divided into 4 groups of 3 animals each. Control group (CG) did not receive any irradiation and/or eye drop. The other three experimental groups were treated as follows: the first group received only UVR irradiation for 30 min, without eye drop supplementation (Irradiation group, IG), the second (G30) and the third (G60) groups received UV irradiation for 30' and 60', respectively, and eye drop supplementation (riboflavin, d-α-tocopheryl polyethylene glycol, proline, glycine, lysine and leucine solution) every 15 min for three hours. In the IG group a significant increase of oxidized glutathione (GSSG) and hydrogen peroxide (H2O2) was recorded in the aqueous humor, whereas ascorbic acid levels were significantly lower when compared to control eyes. In the groups exposed to UVR rays for 30 min, and treated with the topical antioxidant formulation, the GSSG, H2O2 and ascorbic acid levels were similar to those recorded in controls, whereas in the G60 group the three markers significantly differ from control group. In the lens, a significant decrease of alpha tocopherol and total antioxidant capacity (TAC) was recorded in IG-animals as compared to control group, whereas malondialdehyde (MDA) levels were significantly higher in UV-induced eye than in control eyes. In the G30 groups the alpha tocopherol, MDA and TAC levels do not significantly differ from those recorded in controls, whereas in the G60 group these three markers significantly differ from control group. Present findings demonstrate that topical treatment with the antioxidant formulation used herein protects ocular structures from oxidative stress induced by UV exposure in in vivo animal model

    Brand e Country of Origin: una ricerca sulle preferenze del consumatore di olio extra-vergine d\u2019oliva

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    Il paper sintetizza i primi risultati di una ricerca volta ad approfondire le preferenze del consumatore verso l\u2019olio extravergine d\u2019oliva (EVO), mettendo contemporaneamente a confronto specifici attributi del prodotto, al fine di comprenderne l\u2019importanza nel processo di scelta dei consumatori. La ricerca empirica \ue8 basata su un questionario strutturato e articolato in diverse parti (dati sociodemografici, comportamento d\u2019acquisto di olio EVO, conoscenza del prodotto, fattori rilevanti nella decisione d\u2019acquisto, esperimento di scelta). Dai primi risultati emerge che gli intervistati ritengono importante nella scelta di una bottiglia di olio EVO soprattutto la variabile \u201corigine\u201d, con la presenza della certificazione DOP, mentre sembrano non trarre utilit\ue0 dalla certificazione biologica e dalla presenza di un marchio leader. Di interesse ai fini dell\u2019analisi dell\u2019eterogeneit\ue0 degli intervistati, sono inoltre i risultati derivanti dall\u2019applicazione del modello a classi latenti, che ha permesso di identificare quattro gruppi di consumatori, con diverse caratteristiche e preferenze d\u2019acquisto
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