UNA PROPUESTA PARA ENSEÑAR EL EFECTO DE LA FORMA DE LAS MOLÉCULAS EN LA REACTIVIDAD QUÍMICA

We address the concept of steric effect in the pursuit of establishing quantitative correlations between reactivity of molecules and their molecular shape. To this end, a set of series of SN2 reactions were modeled to compute the energy barrier height and the molecular volume, atomic charges and dipole moment of molecules. We introduced the Kappa index to characterize the shape of molecules. Quantitative correlations between the change in the energy barrier with properties of molecules and Kappa index were presented and discussed.

Quantitative analysis of two important epidemiological features of the common bean: Phaeoisariopsis griseola pathosystem

This work quantifies two important epidemiological features of the bean (Phaseolus vulgaris)/Phaeoisariopsis griseola pathosystem. The first is the effect of the number of nights of leaf wetness on infection efficiency. Infection efficiency was below 10% when inoculated leaflets were exposed to less than two nights of leaf wetness. Optimum infection efficiencies were obtained after three to four nights of leaf wetness, at about 50%. Further nights of leaf wetness did not increase the infection efficiency. The second feature quantified is the relative rate of leaflet defoliation for varying levels of angular leaf spot severity. It increased with disease severity according to a logarithm-like curve, and a relative rate of 0.23 day-1 was estimated for a severity of 18%. The implications of these results on the disease epidemiology are discussed.

Flow injection visible diffuse reflectance quantitative analysis of total sulfur in biodiesel, in plant leaves and in natural waters

Flow injection (FI) methodology, using diffuse reflectance in the visible region of the spectrum, for the analysis of total sulfur in the form of sulfate, precipitated in the form of barium sulfate, is presented. The method was applied to biodiesel, to plant leaves and to natural waters analysis. The analytical signal (S) correlates linearly with sulfate concentration (C) between 20 and 120 ppm, through the equation S=-1.138+0.0934 C (r = 0.9993). The experimentally observed limit of detection is about 10 ppm. The mean R.S.D. is about 3.0 %. Real samples containing sulfate were analyzed and the results obtained by the FI and by the reference batch turbidimetric method using the statistical Student's t-test and F-test were compared.

Spot-test identification and rapid quantitative sequential analysis of dipyrone

A qualitative spot-test and tandem quantitative analysis of dipyrone in the bulk drug and in pharmaceutical preparations is proposed. The formation of a reddish-violet color indicates a positive result. In sequence a quantitative procedure can be performed in the same flask. The quantitative results obtained were statistically compared with those obtained with the method indicated by the Brazilian Pharmacopoeia, using the Student's t and the F tests. Considering the concentration in a 100 µL aliquot, the qualitative visual limit of detection is about 5×10-6 g; instrumental LOD ≅ 1.4×10-4 mol L-1 ; LOQ ≅ 4.5×10-4 mol L-1.

Le concept de plateau chez Deleuze et Guattari : ses implications epistemologique et ethique

Neste artigo, interrogamos os funcionamentos do conceito de platô em "Mil Platôs" (1980), a obra-prima de Deleuze e Guattari. Essa pesquisa esclarece, de forma concreta, duas linhas de pensamento, que são a epistemológica, por um lado, e a ética, por outro, enfocando os parágrafos nos quais Deleuze e Guattari usam efetivamente esse conceito. Do ponto de vista epistemológico, o conceito de platô permite praticar uma maneira de escrita rizomática e a explicação antiteleológica. Do ponto de vista ético, esse conceito, tirado de Gregory Bateson, nos convida a formar a alegria contínua e global, ou a gaieté em termos espinosistas.

THE CONCEPT OF 'NATURE' IN ARISTOTLE, AVICENNA AND AVERROES

This study is concerned with 'nature' specifically as the subject-matter of physics, or natural science, as described by Aristotle in his "Physics". It also discusses the definitions of nature, and more specifically physical nature, provided by Avicenna (d. 1037) and Averroes (d. 1198) in their commentaries on Aristotle's "Physics". Avicenna and Averroes share Aristotle's conception of nature as a principle of motion and rest. While according to Aristotle the subject matter of physics appears to be nature, or what exists by nature, Avicenna believes that it is the natural body, and Averroes holds that the subject matter of physics or natural science consists in the natural things, in what constitutes a slight shift in focus.

Quantitative control of Lettuce mosaic virus fitness and host defence inhibition by P1-HCPro

Two Lettuce mosaic virus isolates capable of overcoming the resistance afforded by the resistance gene mo1² in lettuce, LMV-AF199 from Brazil, and LMV-E, an European isolate, were evaluated for the rapidity and severity of symptoms induced on the lettuce variety Salinas 88 (mo1²). The mosaic symptoms on Salinas 88 plants inoculated with LMV-AF199 appeared 7 days post-inoculation (dpi) and 15 dpi for LMV-E. The symptoms induced by LMV-AF199 in this cultivar were also more severe than those induced by LMV-E. In order to identify the region of the viral genome responsible for this phenotype, recombinant viruses were constructed between these isolates and the phenotype of each recombinant was analysed. The region encoding proteins P1 and HcPro from LMV-AF199 was associated with the increased virulence in Salinas 88.

Quali/quantitative characterization of biogas produced in batch digesters supplied with six distinct substrates

The present research was carried out at the DER/FCAV, São Paulo State University - Brazil, with the purpose of analyzing the quantity and quality of biogas produced by six types of substrates. The substrates used in the anaerobic digestion were characterized as: 1- Litter of broiler (LB); 2- Grinded broiler litter (GBL); 3- Broiler litter with wood shavings (BLWS); 4- Grinded broiler litter with wood shavings (GBLWS); 5- Broiler litter with peanut hulls (BLPH); 6- Grinded broiler litter with peanut hull (GBLPH). It was concluded from the collected data that: the (GBL) substrate showed a superior biogas accumulated production in relation to the other substrates, while the BLWS presented an inferior accumulated production; the grinded substrates showed higher quantities of accumulated biogas in relation to the non-grinded substrates, except for GBLPH, with 20.9 m³ inferior than BLPH; the period of maximum biogas production started from 45 to 60 days, declining after 120 days; at 57 days after filling up the digesters the biogas produced had levels of CH4 superior than 53%, and from 99 days all of them produced biogas with levels of CH4 superior than 70%; LB and GBL presented higher concentrations of CH4 in the biogas.

Low-flow estimates in regions of extrapolation of the regionalization equations: a new concept

ABSTRACT Knowledge of natural water availability, which is characterized by low flows, is essential for planning and management of water resources. One of the most widely used hydrological techniques to determine streamflow is regionalization, but the extrapolation of regionalization equations beyond the limits of sample data is not recommended. This paper proposes a new method for reducing overestimation errors associated with the extrapolation of regionalization equations for low flows. The method is based on the use of a threshold value for the maximum specific low flow discharge estimated at the gauging sites that are used in the regionalization. When a specific low flow, which has been estimated using the regionalization equation, exceeds the threshold value, the low flow can be obtained by multiplying the drainage area by the threshold value. This restriction imposes a physical limit to the low flow, which reduces the error of overestimating flows in regions of extrapolation. A case study was done in the Urucuia river basin, in Brazil, and the results showed the regionalization equation to perform positively in reducing the risk of extrapolation.

A new concept in prophylaxis and therapy: paramunization by poxvirus inducers

The so-called primitive, innate or paraspecific immune system is the phylogenetically older part of the complex immune system. It enables the organism to immediately attack various foreign substances, infectious pathogens, toxins and transformed cells of the organism itself. ,,Paramunity" is defined as an optimal regulated and activated, antigen-nonspecific defence, acquired through continuous active and succesful confrontation with endogenous and exogenous noxes or by means of ,,paramunization" with so called ,,paramunity inducers". Paramunity inducers based on different pox virus species (e.g. Baypamun®, Duphapind®, Conpind) have turned out to be effective and safe when applied with human beings as well as with animals. Pox virus inducers activate phagocytosis and NK-cells in addition to regulation of various cytokines, notably interferon a and g, IL 1, 2, CSF and TNF which comprise the network of the complex paraspecific immune system. The results of experimental work as well as practical use in veterinary medicine have shown that paramunization by pox inducers goes far beyond the common understanding of so-called ,,immuno-therapy". They are ,,bioregulators", because they have 1. a regulatory effect on a disturbed immune system in the sense of an optimal homoeostasis, and 2. simultaneously a regulatory effect between the immune, nervous, circulatory and hormone system. Therefore, the use of paramunization by pox inducers opens a new way of prophylaxis and therapy, not only with regard to infections, but also with regard to different other indications.

Experimental poisoning by Senecio brasiliensis in calves: quantitative and semi-quantitative study on changes in the hepatic extracellular matrix and sinusoidal cells

Extracellular matrix plays an important role in chronic hepatic lesions and has been studied in experimental intoxication models. However in cattle, studies on chronic disease have focused on the hepatocellular damage and extracellular matrix (ECM) changes are usually overlooked. There are no specific studies on the hepatic ECM in either normal or chronically damaged bovine liver. Thus an experimental model of hepatic toxicity model using Senecio brasiliensis poisoned calves was designed. Senecio brasiliensis contains pyrrolizidine alkaloids which cause either acute or chronic progressive dose dependent liver damage. Five calves were orally fed with 0.38g of dry leaves of S. brasiliensis/kg/day for 24 days. Liver needle biopsy specimens were obtained every 15 days for 60 days. Clinical signs of digestive complications appeared at 3rd week. One calf died on 45th day and four were evaluated up to 60th day. Biopsy samples were processed for routine light microscopy, immuno-histochemistry and transmission electron microscopy. From 30th day on progressive liver damage characterized by hepatocellular ballooning, necrosis, apoptosis and megalocytosis, centrilobular, pericellular and portal fibrosis were seen by light microscopy. Quantitative and semi-quantitative measurements of hepatic ECM components were performed before and after the onset of lesions. Morphometric analysis of total collagen and elastic fiber system was conducted. Total collagen and I and III collagen types progressively increased in throughout the liver of affected calves. Changes in location, amount and disposition of the elastic fiber system were also observed. Then numbers of Kupffer cells were significantly increased at 30th day and total numbers of sinusoidal cells were significantly increased at 45th and 60th days. Liver damage was progressive and irreversible even after the exposure to the plant was discontinued. Severe fibrotic lesions occurred mainly in portal tracts, followed by veno-occlusive and pericellular fibrosis. Collagen types I and III s were present in every normal and damaged liver, with predominance of type I. In affected calves the increase of total collagen and elastic fibers system paralleled the number of total sinusoidal cells.

Molecular diagnosis of Anaplasma marginale in cattle: quantitative evaluation of a real-time PCR (Polymerase Chain Reaction) based on msp5 gene

The rickettsia Anaplasma marginale is considered the main agent of bovine anaplasmosis. Due the nonspecific clinical signs of the anaplasmosis, the diagnosis of infection depends of laboratory confirmation. In recent years, molecular diagnostic methods have been used to detect A. marginale in cattle. However, the existence of a large number of assays of different sensitivity and cost makes the choice of an appropriate test difficult. In the present study, a real-time Polymerase Chain Reaction (PCR) based on the msp5 target gene was quantitatively assessed and compared to an end point PCR. Both reactions were subjected to sensitivity and specificity evaluation using plasmid DNA and samples from cattle experimentally infected with A. marginale. A comparative field trial of the tests was carried out using samples of cattle from a stable enzootic area for A. marginale. The real-time PCR showed a higher sensitivity than the end point PCR. This reaction (i.e. real-time PCR) was able to detect one copy of the msp5 gene in 100 ηg of plasmidial DNA, and more than 80% of its results were positive among experimentally infected animals seven days after infection. In addition, based on in silico analysis, the real-time PCR evaluated in the present study appears to be useful for the detection of A. ovis.

Leaf blade quantitative anatomy of sugarcane cultivars and clones

The objective of this study was to make a quantitative assess of the anatomic characteristics of leaf blade of the sugarcane cultivars RB855113, SP80-1842, SP80-1816, RB867515 and clone RB957689 presenting different sensitivity to the mixture of sodium trifloxysulfuron + ametryn herbicides. Compared to the other cultivars assessed, RB855113 cultivar, considered more sensitive to the herbicide mixture, presented relevant differences such as greater proportion of bulliform cells, greater tissue proportion in the transverse section of the leaf blade, greater stomata and trichome density on both surfaces, thinner epidermis on the adaxial surface and length of stomata on both surfaces. The external paraclinal wall of the bulliform cells was thinner than in the common epidermis cells in all the genotypes on the adaxial and abaxial surfaces. Multivariate analysis of the data on the variables considered most relevant to explain the herbicide penetration singled out the sensitive RB855113 from the other materials. Such characteristics can explain the greater penetration, and consequently, greater sensitivity of this cultivar to the sodium trifloxysulfuron + ametryn mixture.

Quantitative variables applied to phenological studies of Sargassum vulgare C. Agardh (Phaeophyceae - Fucales) from Ilha Grande Bay, State of Rio de Janeiro

The suitability of quantitative variables for phenological studies was evaluated in a population of the brown seaweed Sargassum vulgare from "Praia das Gordas", Angra dos Reis, Ilha Grande Bay, state of Rio de Janeiro. From June 1998 to May 1999, twenty adult individuals were randomly sampled at bimonthly intervals. Fifteen variables related to the vegetative and reproductive development of perennial and non-perennial parts of the individuals were quantified. Variables related to the non-perennial parts were more useful than those related to the perennial parts, because they showed a clear variation over the year. Vegetative development declined from June to October, and increased from October to February, when maximum median values of thallus height, total dry mass, non-perennial parts dry mass, and degree of branching were reached. This pattern coincided with those described for other species of the genus from warm temperate regions. Thallus height, a usually employed character in other phenological studies of Sargassum, showed lower coefficient of variation (53.2%) than those related to dry mass (72.0% to 182.3%). Peak of reproduction occurred from June to August, according to the following variables: fertile primary lateral branches number and dry mass and receptacles dry mass. Non-perennial parts dry mass and receptacles dry mass are recommended for phenological studies of S. vulgare. This methodological procedure avoids the sampling of the whole individual and warrants its regeneration from the perennial parts.

The position of the hyaline papilla and the genus concept of Cheilolejeunea (Spruce) Schiffn. (Lejeuneaceae)

In this paper, the genus concept of Cheilolejeunea is discussed and revalued based upon the concept of the real position of the hyaline papilla, as well as upon the definition of apical tooth of the lobule in the genus.