Antenna theory in resonating systems derived from fundamental electromagnetism

Theoretische Elektrotechnik, Elektromagnetische Verträglichkeit, Antennentheorie, Elektrodynamik, Mathematische Methoden der Physik, Leitungstheorie, Mikrowellentechnik, Hohlraumresonatoren

Modelling and analysis of a production plant for low density polyethylene

Dynamic model, tubular reactor, polyethylene, LDPE, discretization, simulation, sensitivity analysis, nonlinear analysis

Pentoxifylline Attenuates Cardiac Remodeling Induced by Tobacco Smoke Exposure

Abstract Background: Tobacco smoke exposure is an important risk factor for cardiac remodeling. Under this condition, inflammation, oxidative stress, energy metabolism abnormalities, apoptosis, and hypertrophy are present. Pentoxifylline has anti‑inflammatory, anti-apoptotic, anti-thrombotic and anti-proliferative properties. Objective: The present study tested the hypothesis that pentoxifylline would attenuate cardiac remodeling induced by smoking. Methods: Wistar rats were distributed in four groups: Control (C), Pentoxifylline (PX), Tobacco Smoke (TS), and PX-TS. After two months, echocardiography, invasive blood pressure measurement, biochemical, and histological studies were performed. The groups were compared by two-way ANOVA with a significance level of 5%. Results: TS increased left atrium diameter and area, which was attenuated by PX. In the isolated heart study, TS lowered the positive derivate (+dp/dt), and this was attenuated by PX. The antioxidants enzyme superoxide dismutase and glutathione peroxidase were decreased in the TS group; PX recovered these activities. TS increased lactate dehydrogenase (LDH) and decreased 3-hydroxyacyl Coenzyme A dehydrogenases (OH-DHA) and citrate synthase (CS). PX attenuated LDH, 3-OH-DHA and CS alterations in TS-PX group. TS increased IL-10, ICAM-1, and caspase-3. PX did not influence these variables. Conclusion: TS induced cardiac remodeling, associated with increased inflammation, oxidative stress, apoptosis, and changed energy metabolism. PX attenuated cardiac remodeling by reducing oxidative stress and improving cardiac bioenergetics, but did not act upon cardiac cytokines and apoptosis.

Contribuição ao estudo do «vermelhão» do algodoeiro (Gossipium herbaceum)

During the years 1948, 1949 and 1951 a disease occurred in the cotton crops of the state of S. Paulo Brazil (S. Am.), which caused a severe drop in yields. The abnormality was characterized by a typical reddish - purple color of the leaves, being by this reason, called "vermelhão", that is, reddening of the cotton plant. The disease was associated with a dry season. Among the several hypotheses raised to explain the causes of the disease were: insect attack, potassium deficiency - where from the name "potash hunger" was also given -, and magnesium deficiency: In order to study the problem the Department of Agricultural Chemistry of the College of Agriculture of the University of São Paulo, at Piracicaba, carried out a series of experiments as follows: 1. pot experiments in which soil of one of the affected regions was used ("terra roxa", a red-brownish soil derived from basalt); 2. pot-soil experiments varying the moisture supplied; 3. sand culture experiments omitting certain elements from the nutrient solutions; 4. field plot experiments, conducted on a sandy soil; three different varieties were employed: Texas, Express, and I.A. 817; magnesium was applied either as sulfate or dolomitic limestone. All the experiments were completed with suitable chemical analyses. The results can be summarized as follows: 1. in the first trial, the not properly manured pots (minus Mg), symptoms were registered which were similar to the symptoms observed in the field; it was possible to establish some differences among three different types of reddening: due to lack of K in the mixed fertilizers used, the characteristic cotton rust made its appearance, the red color in the leaves of the minus Mg plants was all alike that described in the current literature as a symptom of Mg-deficiency; in all the treatments ocurred a yellow-reddish color in the leaves associated with the latest stages of maturity; 2. in the second experiment it was verified that when the plants in the pots with soil were kept 75 per cent of the water holding capacity, no symptom of deficiency showed up; was true even for the plants not receiving neither K nor Mg; however, plants supplied with only 25 per cent of the water holding capacity showed, respectively, cotton rust in the minus K treatment and the red purplish color in the minus Mg series; 3. the sand culture experiment confirmed lack of Mg as the cause of "vermelhão", being potash deficiency the responsible for cotton rust; 4. in the field experiment, variety LA. 817 revealed to be the most sensitive to "vermelhão" when Mg was omitted from the fertilizers; symptoms of K deficiency appeared when no K was supplied; both magnesium sulfate and dolomitic limestone proved to be equally effective in the control of "vermelhão"; 5. the analyses of material collected both in the field as well in the pots revealed that leaf petiole in the most reliable part to indicate the K and Mg status of the plant; the variation in Mg content suffered by the plants showing different stages of "vermelhão was, quantitatively, at least as large as that in K content, however when one deals with K deficient plants, that is, plants showing the typical rust, no variation occurred in the Mg content, whereas K in the dry mater dropped from more than 1 per cent to less than half per cent. Then, the following general conclusions can be drawn: 1. Mg deficiency is the cause of "vermelhão" of cotton crops; 2. K deficiency also occurred, but in a lesser degree; 3. the climate conditions - especially the lack of rain influenced the soil dynamic of K, and especially Mg, bringing a severe reduction in their assimilability; 4. the "vermelhão" disease can be easily controlled upon additions either of magnesium sulfate or dolomitic limestone.

Nitrificação e aproveitamento de alguns adubos nitrogenados

The rate of nitrification of several nitrogenous fertilizers (ammonium sulfate, nitre-chalk, ureia, and cottonseed meal) was studied in three soils, namely, "terra roxa legítima", a red soil derived from basalt, "terra roxa misturada", a soil also derived from basalt but with a higher proportion of sand, and "areito Corumbataí", a sandy soil. The effects of the following treatments on nitrification were considered: addition of limestone of micronutrients (Fe, Cu, Zn, Mn, and Mo), and inoculation with a suspension of spores of Aspergillus wentii, a heterotrophic nitrifier. The results showed that: in "terra roxa legítima" limestone had no influence on the nitrification rate, whereas the micronutrients estimulated the oxidation of nitre-chalk, cottonseed meal and urea; inoculation with A. wentii helped only the nitrification of ammonium sulfate and of the cottonseed meal; the latter, in all the treatments employed gave use to a smaller amount of nitrates; in "terra roxa misturada", all the fertilizers depending upon the treatments they were subjected to, presented maximum values for nitrification; limestone estimulated the oxidation of ammonium sulfate as well as the mineralization of the cottonseed meal; the addition of micronutrients helped the nitrification of all the fertilizers, except that of urea; inoculation showed a benefical influence on the nitrification of ammonium sulfate and cottonseed meal; in "arenito de Corumbatai", the amounts of nitrates produced was roughly the same for all the fertilizers investigated; limestone estimulated the nitrification of nitro-chalk, ammonium sulfate and cottonseed meal whilst the addition of micronutrients benefited only the latter two; the inoculation with A. wentii helped the oxidation of all the fertilizers. In order to study the availability of the various fertilizers above discussed, two plant growing experiments were carried cut, one in pots, using the three soil types and another one in the field, with "terra roxa misturada". In "arenito de Corumbatai" there was no significant difference in the yield both of straw and rice grains for none of the fertilizers: Chilean nitrate of soda was used as a control; ho marked agreement could be detected between the data concerning nitrification and the yield results. In "terra roxa legítima", ammonium sulfate won the competition and there was a good parallelism between nitrification and yield. In "terra roxa misturada", there was no statistical difference among the various fertilizers; the agreement between nitrification and yields was reasonable. In the field (corn), Chilean nitrate, ammonium sulfate and nitro-chalk were clearly beter than urea and cottonseed meal which did not differ from the minus nitrogen plots.

Tracer studies in the coffee plant (Coffea arabica L.)

Due to the great importance of coffee to the Brazilian economy, a good deal of the work carried out in the "Laboratório de Isótopos", E. E. A. "Luiz de Queiroz", Piracicaba, S. Paulo, Brazil, was dedicated to the study of some problems involving that plant. The first one was designed to verify a few aspects of the control of zinc deficiency which is common in many types of soils in Brazil. An experiment conducted in nutrient solution showed that the leaf absorption of the radiozinc was eight times as high as the root uptake; the lower surface of the leaves is particularly suited for this kind of absorption. Among the heavy metal micronutrients, only iron did not affect the absorption of the radiozinc; manganese, copper, and molybdenum brought about a decrease of fifty per cent in total uptake. In another pot experiment in which two soils typical of the coffee growing regions were used, namely, a sandy soil called "arenito de Bauru" and a heavy one, "terra roxa", only O.l and 0.2 per cent of the activity supplied to the roots was recovered", respectively. This indicates that under field conditions the farmer should not attempt to correct zinc deficiency by applying zinc salts to the soil: leaf sprays should be used wherever necessary. In order to find out the most suitable way to supply phosphatic fertilizers to the coffee plant, under normal farm conditions, an experiment with tagged superphosphate was carried out with the following methods of distribution of this material: (1) topdressed in a circular area around the trees; (2) placed in the bottom of a 15 cm deep furrow made around the plant; (3) placed in a semicircular furrow, as in the previous treatment; (4) sprayed directly to the leaves. It was verified that in the first case, circa 10 per cent of the phosphorus in the leaves came from the superphosphate; for the other treatments, the results ware, respectively: 2.4, 1.7, and 38.0 per cent. It is interesting to mention that the first and the last methods of distribution were those less used by the farmers; now they are being introduced in many coffee plantations. In a previous trial it was demonstrated that urea sprays were an adequate way to correct nitrogen deficiency under field conditions. An experiment was then set up in which urea-C14 was used to study the metabolism of this fertilizer in coffee leaves. In was verified that in a 9 hours period circa 95 per cent of the urea supplied to the leaves had been absorbed. The distribution of the nitrogen of the urea was followed by standard chemical procedures. On the other hand the fate of the carbonic moiety was studied with the aid of the radiochromatographic technique. Thus, the incorporation of C14 in aminoacids, sugars and organic acids was ascertained. Data obtained in this work gave a definite support to the idea that in coffee leaves, as in a few other higher plants, a mechanism similar to the urea cycle of animals does exist.

Estudos sôbre alimentação mineral do cafeeiro: VIII. Estudo da absorção e da translocação do radiozinco no cafeeiro (Coffea arabica L.)

WATER-CULTURE EXPERIMENTS. Two water-culture experiments were carried out to study the absorption and the translocation of radiozinc in young coffee plants as influenced by two factors, namely, concentration of heavy metals (iron, man ganese, copper and molybdenum) and method of application. Inert zinc was supplied at an uniform rate of 0. 05 p. p. m.; the levels of iron supply were 0, 1.0, and 10.0 p. p.m.; manganese was supplied in three doses 0, 0.5, and 5.0 p. p.m.; copper- 0, 0. 02, and 0. 2 p. p. m.; molybdenum- 0, 0. 01, and 0. 1 p. p. m. When applied to the nutrient solution the activity os the radiozinc (as zinc chloride) was 0. 15 microcuries per plant. In the study of the leaf absorption, Zn65 was supplied at the level of 0. 10 microcuries per plant; in this case the radioative material was brushed either on the lower or on the upper surface or both two pairs of mature leaves. The absorption period was 8 weeks. The radioactivity assay showed the following results: 1 - Among the heavy metals herein investigated the iron concentration did not affect the uptake of the radiozinc; by raising the level of Mn, Cu and Mo ten times, the absorption dropped to 50 per cent and even more when compared with the control plants; when, however, these micronutrients were omitted from the nutrient solution, an increase in the uptake of zinc was registered in the minus Cu treatment only. The effects of high levels of Mn, Cu and Mo probably indicate an interionic competition for a same site on a common binding substance in the cell surface. 2 - The absorption of the radiozinc directly applied to the leaf surface reached levels as high as 8 times that registered when the root uptake took place. Among the three methods of application which have been tried, brushing the lower surface of the leaves proved to be the most effective; this result is easily understood since the stomatal openings of the coffee leaves an preferentially located in the lower surface - in this treatment, about 40 per cent of the activity was absorved and around 12 per cent were translocated either to the old or to the newer organs. Chemical analyses for heavy metals, were carried out only in the plants received Zn65Cl2 in the nutrient solution; the results were as follows; 1 - Control plants had, per 1,000 gm, of dry weight the following amounts in mg.: Zn- 48 in the roots and 29 in the tops; Fe- 165 in the roots and 9 in the tops; Mn- 58 in the roots and 15 in the tops, Cu- 15 in the roots and 1. 2 in the tops; Mo- 2. 8 in the roots and 0. 45 in the tops. 2 - The effect of different levels of micronutrients in the composition of the plants can be summarized as follows: Fe and Zn- when omitted from the nutrient solution, the iron and zinc contents in the roots decreased, no variation being noted in the tops; the higher dosis caused an accumulation in the roots but no apparent effect in the tops; Mn- by omitting this micronutrient a decrease in its content in the roots was noted, where as the concentration in the tops was the same; Mo- no variation in roots and tops contents when molybdenum was omitted; higher dosis of manganese and molybdenum increased the amounts formed both in the roots and in the tops. 3 - The influence of the different concentrations of micronutrients heavy metals on the zinc content of the coffee plants can be described by saying that: Fe and Mo- no marked variation; Mn- no effect when omitted, reduced amount when the high dosis was supplied; Mn- when the plants did not receive manganese the zinc content in roots and tops was the same as in the control plants; a decrease in the zinc content of the total plant occurred when the high dosis was employed; Cu -the situation is similar to that described for manganese. Hence, results showed by the chemical analyses roughly correspond to those of the radioactivity assay; the use of the tracer technique, however, gave best informations along this line. SOIL-POTS EXPERIMENTS. The two types of soils which when selected support the most extensive coffee plantations in the State of São Paulo, Brazil: "arenito de Bauru", a light sandy soil and "terra roxa legitima", a red soil derived from basalt. Besides NPK containing salts, the coffee plants were given two doses of inert zinc (65 and 130 mg ZnCl2 per pot) and radiozinc at a total activity of 10(6) counts/minute. The results of the countings can be summarized as follows: 1 - When plants were grown in "arenito de Bauru" the activity absorbed as per cent of the total activity supplied was not affected by the dosis of inert zinc. The highest value found was around 0. 1 per cent. 2 - For the "terra roxa" plants, the situation is almost the same; there was, however, a slight increase in the absorption of the radiozinc when 130 mgm of ZnClg2 was given: a little above 0. 2 per cent of the activity supplied was absorbed. The results clearly show that the young coffee plants practically did not absorb none of the zinc supplied; two reasons at least could be pointed out to explain such a fact: 1 - Zinc fixation by an exchange with magnesium or by filling holes in the octahedral layer of aluminosilicates, probably kaolinite; 2 - No need for fertilizer zinc in the particular stage of life cycle under which the experiment was set up. The data from chemical analysis are roughly parallel to the above mentioned. When one attempts to compare - by taking data herein reported zinc uptake from nutrient solution, leaf brushing or from fertilizers in the soil, a practical conclusion can be drawn: the control of zinc deficiency in coffee plants should not be done by adding the zinc salts to the soil; in other words: the soil applications used so extensively in other countries seem not to be suitable for our conditions; hence zinc sprays should be used wherever necessary.

Studies on the mineral nutrition and fertilization of the passion fruit plant (Passiflora edulis f. flavicarpa): II - placement of fertilizer phosphorus

A localização do superfosfato (marcado com P32) no maracujá em produção foi estudada em condições de plantação comercial. Verificou-se que as aplicações em sulcos circulares ou faixas superficiais ao redor da planta tem eficiência equivalente sendo esses métodos três vezes superiores à localização do adubo em furos no solo. A pulverização foliar, por sua vez, mostrou-se 20 vezes mais eficiente que a aplicação no solo de acordo com os dois primeiros métodos.

Notes on Calvatia (Lycoperdaceae), II : Calvatia cretacea (Berk.) Lloyd, an Arctic montane plant / Patricio Ponce de Leon.

v.38:no.3(1976)

Stink bugs (Heteroptera, Pentatomidae) and an unique host plant in the Brazilian subtropics

Stink bugs are seed/fruit sucking insects feeding on an array of host plants. Among them, an exotic tree called privet, Ligustrum lucidum Ait. (Oleaceae), is very common in the urban areas of the Brazilian subtropics, where it is utilized as food source and shelter for over a decem species of bugs, year round. The species composition, their performance and abundance on this host, and possible causes for this association are discussed and illustrated.

Estrutura floral das angiospermas usadas por Heliconius erato phyllis (Lepidoptera, Nymphalidae) no Rio Grande do Sul, Brasil

A field survey of flowering plants used as food resource by the adults of Heliconius erato phyllis (Fabricius, 1775) was carried out in four sites located in Rio Grande do Sul state, Brazil. Samples were taken in preserved areas of the Atlantic Rain and Myrtaceae forests, an Eucalyptus plantation, and an urban park. Adult feeding frequencies on flowers were registered monthly from December 1996 to May 1997, on plants located on previously marked 200 m long transects. Flowers on which H. erato phyllis fed in the field were collected, drawn and morphometrically characterized. Feeding was registered on flowers of twenty-three species, of which seventeen are new records for H. erato in Brazil . The use of a given plant varied among localities, as a function of its corresponding abundance. The most visited flowers were those of Lantana camara L. and Stachytarpheta cayennensis (Rich.) Vahl, followed by Dahliapinnata Voss in the urban site. The data suggest the existence of size and shape convergence between the proboscis and the small, tubular flowers upon which H. eratophyllis feeds. They also indicate that H. eratophyllis adults have an opportunistic nectar feeding / pollen gathering habit, using several of those flowers available in a given time and locality that fit such a morphometrical pattern. Since plant species of both primitive and derived families are used, there is no indication that phylogenetic constraints play a major role in this association, nor that color of flowers, growth pattern or size of the plants are relevant in determining their use by H. erato phyllis.

Impact of a power plant cooling system on copepod and meroplankton survival (Bahía Blanca estuary, Argentina)

The impact of a power plant cooling system in the Bahía Blanca estuary (Argentina) on the survival of target zooplanktonic organisms (copepods and crustacean larvae) and on overall mesozooplankton abundance was evaluated over time. Mortality rates were calculated for juveniles and adults of four key species in the estuary: Acartia tonsa Dana, 1849 and Eurytemora americana Williams, 1906 (native and invading copepods), and larvae of the crab Chasmagnathus granulata Dana, 1851 and the invading cirriped Balanus glandula Darwin, 1854. Mean total mortality values were up to four times higher at the water discharge site than at intake, though for all four species, significant differences were only registered in post-capture mortality. The findings show no evidence of greater larval sensitivity. As expected, the sharpest decrease in overall mesozooplankton abundance was found in areas close to heated water discharge.