3,059 research outputs found
Panel de expertos: Reflexiones en torno a las recomendaciones para la toma de decisiones en salud
No full textJuan Gabriel Ruíz Reflexiones sobre toma de Decisiones en Salud , Florida International University (US). I
ván Flórez, Daniel Patiño y Pamela Velásquez, Experiencia de la Unidad de Evidencia y Deliberación para la Toma de Decisiones (UNED) , Facultad de Medicina UdeA (Colombia).
Rita Mattiello, Experiencia de la cátedra de evidencia en salud, aprendizajes y retos , Universidade Federal do Rio Grande do Sul (Brasil
Green synthesis of Ag nanoparticles using plant metabolites
No full textNano-biotechnology is one of the most promising areas in modern nanoscience and technology. In this
emerging area of research, nanoparticles (NPs) play an important role since the large-scale production and huge numbers
of utilization. Gold and silver nanoparticles are among the most extensively studied nanomaterials, since they show high
stability and low chemical reactivity in comparison to other metals. They are commonly synthesized using toxic chemical
reducing agents able to reduce metal ions into uncharged NPs and/or high energy supplied procedures. The most
commonly used method for the synthesis of NPs requires toxic chemicals like N,N-dimethyl formamide (DMF) or
trisodium citrate, but recently a green technique, based on natural reducing agents, has been suggested to substitute the
nature-unfriendly chemical methods. Many scientific works put in evidence the efficacy of plant extracts to reduce metal
salts into the respective NPs, but this process lacks a clear control of NPs shapes and dimensions, since many different
metabolites present into the extracts could participate to the process. This paper aims to clarify the reducing action of
single pure natural compounds usually present in plant tissues and to obtain a stable and reproducible protocol for NPs
synthesis
Rita B. Stadig Correspondence
No full textEntry is a handwritten biographical sketch of Rita Stadig author of Our Maine Heritage, a history of Maine
Keynote Speech by Rita Palacios and Luncheon
No full textRita Palacios holds a Ph.D. in Spanish and is a professor of languages in the School of Liberal Studies at Conestoga College in Kitchener, Ontario. Her research examines contemporary Maya literature from a cultural and gender studies perspective. She is the author of Unwriting Maya Literature: Ts’íib as Recorded Knowledge (with Paul M. Worley).
The luncheon is free for all registered participants
In Vivo synthesis of nanomaterials in plants: location of silver nanoparticles and plant metabolism
No full textMeNPs can be formed in living plants by reduction of the metal ions absorbed as soluble salts. It is very likely that plant metabolism has an important role in MeNP biosynthesis. The in vivo formation of AgNPs was observed in Brassica juncea, Festuca rubra and Medicago sativa. Plants were grown in Hoagland solution for 30 days and then exposed for 24 h to a solution of AgNO3 1000 ppm. In leaf extracts of control plants the concentrations of glucose, fructose, ascorbic acid, citric acid and total polyphenols were determined. Total Ag content in plant fractions was determined by inductively coupled plasma atomic emission spectroscopy.
Despite the short exposure time, the Ag uptake and translocation to plant leaves was very high, reaching 6156 and 2459 mg kg-1 in B. juncea and F. rubra, respectively. Ultrastructural analysis was performed by transmission electron microscopy and AgNPs were detected by TEM X-ray microanalysis. TEM images of plant fractions showed the in vivo formation of AgNPs in roots, stems and leaves of the plants. In the roots, AgNPs were present in the cortical parenchyma cells, on the cell wall of the xylem vessels and in regions corresponding to the pits. In leaf tissues AgNPs of different size and shape were located close to the cell wall, as well as in the cytoplasm and within chloroplasts. AgNPs were never observed in the phloem of the three plant species. This is the first report of AgNP synthesis in living plants of F. rubra. The content of reducing sugars and antioxidant compounds, proposed as being involved in the biosynthesis of AgNPs, were quite different between the species, thus suggesting that it is unlikely that a single substance is responsible for this process
Xanthine scaffold: available synthesis routes to deliver diversity by derivatization
No full textThe functionalization of the skeletal systems of heterocycles represents a significant goal
for the development of new compounds. The heterocyclic molecule xanthine (3,7-dihydro-1Hpurine-
2,6-dione) is a purine base with a bicyclic ring skeleton and four different nitrogen atoms,
three of them are -NH groups. The principal derivatives are the well known natural methylxanthines
(e.g., caffeine, theophylline and theobromine) that have prominent physiological effects at a very low
dose. The natural methylated xanthines, theophylline, theobromine and caffeine, are present in different
plants such as the tea, cocoa and coffee species. For this reason natural xanthines can be considered
as bio-based and renewable starting materials; their use in organic synthesis is strongly recommended
in order to carry out sustainable chemistry. Essentially, the xanthine scaffold led to the
preparation of numerous compounds very attractive in the pharmaceutical field, and these drugs are
commercialized for a wide range of biological activities. The scope of this mini-review is to consider
the use of natural xanthines as starting material in chemical transformations carried out in organic
solvents, without the intent to be exhaustive of all the synthetically chemical applications. More information
on the chemical and electrochemical reactivity of this structural core in an organic solvent
can be useful for the scientific community. The effectiveness of natural xanthines can be improved
by modifying the structures of these already biologically active compounds
Determinantes da composição corporal em crianças e adolescentes
No full textA análise da composição corporal é fundamental não somente para avaliação da obesidade, mas também para conhecer o estado nutricional, o efeito da dieta, da atividade física e diversas alterações associadas ao próprio estado nutricional1. Existem vários fatores que interferem na composição corporal já conhecidos e estudados como idade, peso e altura. Este editorial pretende abordar a importância de outros possíveis determinantes da composição corporal em crianças e adolescentes.
Como citar este artigo: Pérez LM, Mattiello R. Determinantes da composição corporal em crianças e adolescentes. Rev Cuid. 2018; 9(2): 2093-104. http://dx.doi.org/10.15649/cuidarte.v9i2.53
Evidences of genotoxicity and phytotoxicity in Zea mays and Hordeum vulgare exposed to CeO2 and TiO2 nanoparticles
No full textAre the reducing sugars the driving force for Ag nanoparticles biosynthesis in living plants?
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