Vitamina C : una estrategia didáctica polifuncional

El presente trabajo tiene como objetivo contextualizar contenidos curriculares de química: incursionando en el área de bioquímica, como elementos básicos de la formación en química del estudiante; proporcionando información general sobre las propiedades de la vitamina C que permitan al estudiante, como ciudadano, tener libertad de elección frente a la vasta publicidad que se ofrece, entre otros, en los medios masivos de comunicación; aplicando su cultura científica a situaciones de la vida cotidiana y, por lo tanto, valorando la importancia de la educación científica para poder ser capaz de conocer mejor lo que consume y poder opinar en forma crítica sobre ello. Se presentan técnicas sencillas para investigar la presencia de vitamina C en alimentos de uso común. Se discuten distintas estrategias de presentación y tratamiento del tema en los distintos niveles escolares con objetivos diferentes y se analizan cambios en la metodología de trabajo en el aula. Este trabajo fue presentado bajo la modalidad de taller en el XV Congreso Nacional e Internacional de Profesores de Química y los resultados y conclusiones a las que se arribaron fueron ampliamente satisfactorias, ya que permitieron una revalorización de la tarea educativa buscando un currículo más abierto donde el estudiante se sienta partícipe de su proceso de aprendizaje y encuentre contenidos científicos útiles para su vida.This paper attempts to contextualise chemistry curricula contents, entering the field of biochemistry, as basic elements for the formation of chemistry in the student by providing general information on the properties of C vitamin that allows the student, as a citizen, the freedom to choose in front of the huge publicity offered to them, among others, by the mass media. They can apply their scientific culture to everyday life, thus assessing how important scientific education is to be able to better know what is consumed and give a critical opinion. We present simple techniques to find C vitamin in commonly used food. We discuss different strategies to present and deal with this subject at different school levels with different aims, and we analyse the changes in the classroom working methodology. This paper was presented as a workshop in the 15th National and International Congress of Chemistry Professors and its results and conclusion were highly satisfactory, as they allowed revaluing the educational task aiming at a more open curriculum where the student feels part of his learning process and finds scientific contents useful in his everyday life

Changes in some physical properties of a typic haplorthox in southern Brazil under no-tillage crop rotation systems

The assessment of the impacts of different crop rotations on soil physical properties is needed to identify those with the potential to improve such properties which enhance crops´ responses to soil nutrients. The effects of eight crop rotations on physical properties of a Rhodic Ferralsol (Typic Haplorthox) were assessed in Palmital, Svo Paulo, Brazil, using a randomized complete block design with three replications of each treatment. The study lasted for five years (1985 –1990). The crop rotations, planted during the winter from 1985 to 1987, were mucuna, pigeon pea, rye, oat, pisum, wheat, crotalaria and black oat. In 1988 wheat was planted on all plots and from 1989 to 1990, lathyrus, lupin, rye, oat, lupin + black oat, wheat, crotalaria and black oat were planted. The summer crops were maize and soybean. In all treatments and taking the average of all the soil horizons, lupin+black oat and lathyrus produced the lowest bulk density in both maize and soybean plots. When the ranking of the performance of these crop rotations was performed, the order in the maize plots was lupin+black oat > rye > lathyrus > lupin/wheat > oat > crotalaria/black oat. On soybean plots the order was lathyrus > lupin > lupin+black oat > rye > oat > crotalaria > black oat > wheat. It is evident that for the summer crops, lupin+black oat, rye, lathyrus and lupin were consistent in improving these soil physical properties and are therefore, better than the rest of the rotation crops in moderating these properties. Even though there was low improvement in OM content of the soil, OM moderated very significantly bulk density (r =0.602**) and saturated hydraulic conductivity (Ksat) (r = 0.674**) under soybean plots. However, macro-porosity (Pe) had positive improvement in Ksat (r = 0.684**) under maize of all the physical properties measured. Longer lasting crop rotations may produce more positive influences of OM on these soil physical properties. Keywords: Water holding capacity; Aggregate stability; Saturated hydraulic conductivity; Bulk density; Organic matter; Maize; Soybean. Agro-Science Vol. 3 (2) 2006: pp. 1-1

Produção de mudas de mangabeira por semente.

bitstream/item/32371/1/f-04.pdf2. ed

Signature of chaos in gravitational waves from a spinning particle

A spinning test particle around a Schwarzschild black hole shows a chaotic behavior, if its spin is larger than a critical value. We discuss whether or not some peculiar signature of chaos appears in the gravitational waves emitted from such a system. Calculating the emitted gravitational waves by use of the quadrupole formula, we find that the energy emission rate of gravitational waves for a chaotic orbit is about 10 times larger than that for a circular orbit, but the same enhancement is also obtained by a regular "elliptic" orbit. A chaotic motion is not always enhance the energy emission rate maximally. As for the energy spectra of the gravitational waves, we find some characteristic feature for a chaotic orbit. It may tell us how to find out a chaotic behavior of the system. Such a peculiar behavior, if it will be found, may also provide us some additional informations to determine parameters of a system such as a spin.Comment: 14 pages, LaTeX, to appear in Phys. Rev.

CDK2 regulates nuclear envelope protein dynamics and telomere attachment in mouse meiotic prophase

In most organisms, telomeres attach to the nuclear envelope at the onset of meiosis to promote the crucial processes of pairing, recombination and synapsis during prophase I. This attachment of meiotic telomeres is mediated by the specific distribution of several nuclear envelope components that interact with the attachment plates of the synaptonemal complex. We have determined by immunofluorescence and electron microscopy that the ablation of the kinase CDK2 alters the nuclear envelope in mouse spermatocytes, and that the proteins SUN1, KASH5 (also known as CCDC155) and lamin C2 show an abnormal cap-like distribution facing the centrosome. Strikingly, some telomeres are not attached to the nuclear envelope but remain at the nuclear interior where they are associated with SUN1 and with nuclear-envelope-detached vesicles. We also demonstrate that mouse testis CDK2 phosphorylates SUN1 in vitro. We propose that during mammalian prophase I the kinase CDK2 is a key factor governing the structure of the nuclear envelope and the telomere-led chromosome movements essential for homolog pairin

Formation and stability of oil-in-water nanoemulsions containing rice bran oil: in vitro and in vivo assessments

<p>Abstract</p> <p>Background</p> <p>Nanoemulsions have practical application in a multitude of commercial areas, such as the chemical, pharmaceutical and cosmetic industries. Cosmetic industries use rice bran oil in sunscreen formulations, anti ageing products and in treatments for skin diseases. The aim of this study was to create rice bran oil nanoemulsions using low energy emulsification methods and to evaluate their physical stability, irritation potential and moisturising activity on volunteers with normal and diseased skin types.</p> <p>Results</p> <p>The nanoemulsion developed by this phase diagram method was composed of 10% rice bran oil, 10% surfactants sorbitan oleate/PEG-30 castor oil, 0.05% antioxidant and 0.50% preservatives formulated in distilled water. The nanoemulsion was stable over the time course of this study. <it>In vitro </it>assays showed that this formulation has a low irritation potential, and when applied to human skin during <it>in vivo </it>studies, the nanoemulsion improved the skin's moisture and maintained normal skin pH values.</p> <p>Conclusion</p> <p>The results of irritation potential studies and <it>in vivo </it>assessments indicate that this nanoemulsion has potential to be a useful tool to treat skin diseases, such as atopic dermatitis and psoriasis.</p

DEVELOPMENT OF A NUMERICAL MODEL FOR THE STUDY OF AN OSCILLATING WATER COLUMN DEVICE CONSIDERING AN IMPULSE TURBINE

The present work brings a numerical study of an energy conversion device which takes energy from the waves through an oscillating water column (OWC), considering an impulse turbine with rotation in the chimney region through the implementation of a movable mesh model. More precisely, a turbulent, transient and incompressible air flow is numerically simulated in a two-dimensional domain, which mimics an OWC device chamber. The objectives are the verification of the numerical model with movable mesh of the impulse turbine in the free domain from the comparison with the literature and, later, the study of the impulse turbine inserted in the geometry of the OWC device. In order to perform the numerical simulation on the generated domains, the Finite Volume Method (FVM) is used to solve the mass and momentum conservation equations. For the closure of the turbulence, the URANS (Unsteady Reynolds Averaged Navier-Stokes) model k-ω SST is used. To verify the numerical model employed, drag coefficients, lift, torque and power are obtained and compared with studies in the literature. The simulations are performed considering a flow with a Reynolds number of ReD = 867,000, air as the working fluid and a tip speed ratio of λ = 2. For the verification case, coefficients similar to those previously predicted in the literature were obtained. For the case where the OWC device was inserted it was possible to observe an intensification of the field of velocities in the turbine region, which led to an augmentation in the magnitude of all coefficients investigated (drag, lift, torque and power). For the case studied with the tip velocity ratio λ = 2, results indicated that power coefficient was augmented, indicating that the insertion of the turbine in a closed enclosure can benefit the energy conversion in an OWC device

Polymorphous Si thin films from radio frequency plasmas of SiH4 diluted in Ar: A study by transmission electron microscopy and Raman spectroscopy

In this study, we present a detailed structural characterization by means of transmission electron microscopy and Raman spectroscopy of polymorphous silicon (pm-Si:H) thin films deposited using radio-frequency dust-forming plasmas of SiH4 diluted in Ar. Square-wave modulation of the plasma and gas temperature was varied to obtain films with different nanostructures. Transmission electron microscopy and electron diffraction have shown the presence of Si crystallites of around 2 nm in the pm-Si:H films, which are related to the nanoparticles formed in the plasma gas phase coming from their different growth stages, named particle nucleation and coagulation. Raman scattering has proved the role of the film nanostructure in the crystallization process induced ¿in situ¿ by laser heating

Obesity and pre-hypertension in family medicine: Implications for quality improvement

<p>Abstract</p> <p>Background.</p> <p>Prevention of pre-hypertension is an important goal for primary care patients. Obesity is a risk factor for hypertension, but has not been addressed for pre-hypertension in primary care populations. The objective of this study was to assess the degree to which obesity independently is associated with risk for pre-hypertension in family medicine patients.</p> <p>Methods.</p> <p>This study was a retrospective analysis of information abstracted from medical records of 707 adult patients. Multivariable logistic regression was used to test the relationship between body mass index (BMI) and pre-hypertension, after adjustment for comorbidity and demographic characteristics. Pre-hypertension was defined as systolic pressure between 120 and 139 mm Hg or diastolic pressure between 80 and 89 mm Hg.</p> <p>Results.</p> <p>In our sample, 42.9% of patients were pre-hypertensive. Logistic regression analysis revealed that, in comparison to patients with normal body mass, patients with BMI > 35 had higher adjusted odds of being pre-hypertensive (OR = 4.5, CI 2.55–8.11, p < .01). BMI between 30 and 35 also was significant (OR = 2.7, CI 1.61–4.63, p < 0.01) as was overweight (OR = 1.8, CI 1.14–2.92, p = 0.01).</p> <p>Conclusion.</p> <p>In our sample of family medicine patients, elevated BMI is a risk factor for pre-hypertension, especially BMI > 35. This relationship appears to be independent of age, gender, marital status and comorbidity. Weight loss intervention for obese patients, including patient education or referral to weight loss programs, might be effective for prevention of pre-hypertension and thus should be considered as a potential quality indicator.</p

Pruning management of "Marselan" grapevines in the Serra do Sudeste region, in Southern Brazil.

The agronomical behavior of the ?Marselan? grapevine, indicated for the production of high-quality fine wines, is related to the management of the vineyard and the edaphoclimatic conditions of the cultivation region. This work aimed to evaluate the vegetative, productive, and qualitative behavior of ?Marselan? grapevines subjected to the Spur Pruning and Double Guyot pruning systems, cultivated in a municipality belonging to the Serra do Sudeste region, RS state, Brazil. The ?Marselan? grapevines were conducted in a vertical shoot positioning training system over a ?Paulsen 1103? rootstock, in a commercial vineyard located in Encruzilhada do Sul, RS, Brazil. During the 2016/2017 and 2017/2018 cropping seasons the vegetative vigor, the mass of pruned shoots, Ravaz Index, production, and chemical-physical composition of the must were evaluated. The double Guyot pruning system in the ?Marselan? grapevines induced a lower plant vigor, promoted an increase in the number of bunches per plant, bunch mass, production, and yield. The pruning type interferes with the vigor and yield of the ?Marselan? grapes without altering must quality. In the management of the cv. ?Marselan? in the Serra do Sudeste region, Brazil, the double Guyot pruning system is the most indicated