Showing papers by "Federal University of Pernambuco published in 1997"
TL;DR: The phenology of 19 species of plants was followed for two years at Serra Talhada, Pernambuco State, Northeastern Brazil, finding that leaf fall and flush, flowering, and fruiting were almost continuous in the community throughout both the years, but they peaked at different periods.
Abstract: The phenology of 19 species of plants was followed for two years at Serra Talhada, Pernambuco State, Northeastern Brazil. Ten plants of each species were monitored biweekly. All plants had a complete canopy cover from February (well established rainy season) until May-June (just after rains ceased), and all but a few individuals, belonging to six species, were leafless in October-November (peak of the dry season). Leaf fall and flush, flowering, and fruiting were almost continuous in the community throughout both the years, but they peaked at different periods. The peak of leaf flush preceded the rainy season, spurred by occasional rains, followed by flowering early in the rainy season, and then fruiting. Leaf fall became more pronounced after the rainy season. The species covered a whole range of deciduousness, from those which retained their leaves throughout both years to those which were leafless during 6–7 months each year. This was mostly due to the capacity of leaf retention after the onset of the dry season. Autochoric and zoochoric species produced fruits mostly during the rainy season and anemochoric species during the dry period. The patterns of flowering and fruiting were complex. One species did not produce flowers or fruits in either year; five produced flowers and fruits in one year only and two others produced flowers in both years but fruits in only one. Most of the other species had high intraspecific synchrony and produced flowers for a shorter period than fruits.
RESUMEN
A fenologia de 19 especies de plantas foi acompanhada por dois anos, em Serra Talhada, PE. Dez plantas de cada especie foram observadas a intervalos de duas semanas. Todas as plantas tinham a copa completa de fevereiro (estacao chuvosa bem estabelecida) a maio—junho (logo apos o termino das chuvas) e todas, com excecao de poucos individuos pertencentes a seis especies, estavam sem foihas em outubro–novembro (auge da estacao seca). Queda e formacao de folhas novas, floracao e frutificacao foram quase continuas na comunidade, durante 0s dois anos, mas com picos em periodos diferentes. 0 pic0 de formacao de folhas precedeu a estacao chuvosa, impulsionado por chuvas esporadicas, seguido do de floracao, no inicio da estacao de chuvas, e depois pelo de frutificacao. Queda de folhas foi mais pronunciada depois do periodo chuvoso. As especies cobriram toda ma gama de caducifolia, desde as que mantiveram as folhas durante 0s dois anos as que ficaram defoliadas durante 6–7 meses cada ano. Isto deveuse, principalmente, as suas capacidades de reter folhas ao longo da estacao sea. Especies autooricas e zoocoricas produziram frutos principalmente no periodo chuvoso e as especies anemocoricas no periodo seco. Os padroes de floracao e frutificacao foram complexos. Uma especie nao produziu flores ou frutos nos dois anos, cinco produziram flores e frutos apenas em um dos anos e duas outras, em urn dos anos, produziram flores que nao se desenvolveram em frutos. A maioria das outras especies teve alta sincronia intra-especifica e produziu flores por urn periodo mais curto que frutos.
186 citations
TL;DR: Above 6 mg/kg, the macrofilaricidal effect of DEC did not increase with dose; a significant proportion of adult W. bancrofti were not susceptible to DEC during the study period.
Abstract: To assess directly the effect of various doses of diethylcarbamazine (DEC) on adult Wuchereria bancrofti, 31 infected men were randomly assigned to receive an initial single DEC dose of 1 mg/kg (n = 7), 6 mg/kg (n = 10), or 12 mg/kg (n = 14). Beginning 7 d later, the dosage of DEC and duration of treatment were progressively increased for 7–10 weeks. Physical examinations were performed to detect scrotal nodules and the scrotal area was examined by ultrasound (7·5 MHz transducer) to monitor the ‘filaria dance sign’ (FDS), the characteristic pattern of adult worm movement. Of 53 adult worm ‘nests’ that were detected by ultrasound, 22 (41·5%) were DEC-sensitive (FDS became non-detectable and a nodule became palpable at the site); 20 (37·7%) were not sensitive (FDS remained unchanged and detectable and no nodule developed), and 11 (20·8%) showed mixed responses (FDS remained detectable but a palpable nodule developed). All but one sensitive or mixed response occurred within 1 week after the initial single dose. Of 39 ‘nests’ in men who initially received a single 6 or 12 mg/kg dose of DEC, 20 (51·3%) had sensitive responses compared to 2 (14·3%) of 14 ‘nests’ in men who received a single 1 mg/kg dose (P = 0·04). Above 6 mg/kg, the macrofilaricidal effect of DEC did not increase with dose; a significant proportion of adult W. bancrofti were not susceptible to DEC during the study period.
179 citations
TL;DR: IL‐10 and IL‐4 down‐regulate leishmanicidal activity of human Mϕ, in part by inhibiting NO generation by these cells.
Abstract: The host response to Leishmania infection is regulated by a specific pattern of local cytokine production. We investigated the effect of interleukin (IL)-10 and IL-4 on the leishmanicidal activity of human macrophages (M phi). As with L. major, intracellular killing of L. infantum by human M phi was obtained following ligation of surface CD23 or cell treatment with interferon-gamma (IFN-gamma). This leishmanicidal activity required nitric oxide (NO) generation by activated M phi, and it was partially mimicked by cell treatment with chemical NO donors. Addition of recombinant human IL-10 or IL-4 to CD23 mAb or IFN-gamma decreased L. infantum and L. major killing by infected M phi. IL-10 was more potent than IL-4 in inhibiting the leishmanicidal activity of human M phi. Inhibition of Leishmania killing by IL-4 and IL-10 correlated with decreased NO generation from M phi, and was reversed when exogenous NO was added to cell cultures. Therefore, IL-10 and IL-4 down-regulate leishmanicidal activity of human M phi, in part by inhibiting NO generation by these cells.
175 citations
TL;DR: Preliminary results indicate that LLLT is an important tool and brings many benefits for the treatment of many disorders of the maxillofacial region.
Abstract: Objective: The authors analysed the effects of low-level laser therapy (LLLT) on the treatment of maxillofacial disorders. Summary background data: Pioneer work published by Mester et al.1,2 opened a new frontier in the clinical treatment of many disorders with the use of LLLT. Although LLLT is not well accepted in many places, its use is growing steadily in others, including Europe and more recently in Brazil. Methods: One hundred forty-one female and 24 male patients, between 7 and 81 years of age (average = 39.2 years old), suffering from disorders of the maxillofacial region were treated with 632.8-nm, 670-nm, and 830-nm diode lasers at the Laser Center of the Universidade Federal de Pernambuco. The disorders included temperomandibular joint pain, trigeminal neuralgia, muscular pain, aphatae, inflammation, and tooth hypersensitivity both postoperatively and in small hemangiomas. Most treatment consisted of a series of 12 applications (twice a week), and in eight cases a second series was appl...
112 citations
TL;DR: In this paper, the effect of dissolved oxygen on the methanogenic activity of granular sludges, the low substrate levels inside reactors and lower temperatures on the treatment performance were evaluated.
103 citations
TL;DR: It is suggested that assemblages are impelled by food constraints, forcing cofeeding in large seasonal resources, highlighting the ecological importance of figs to these primates.
Abstract: I studied a primate community on a tropical rainforest island, in the northernmost area of the Brazilian Amazonia. While walking through six distinct habitats along a 12-km trail, running toward the center of the island—a remote undisturbed area—I collected data on the use of the different forest types and forest strata by the primate community and the formation of either mixed groups or species assemblages. Five species are present: Cebus olivaceus, C. apella, Saimiri sciureus, Ateles belzubuth, and Alouatta seniculus. They seemed to be habitat generalists, using most habitat types. The five species used the higher strata more significantly, probably because Maraca does not present well-defined forest floors, which could be a result of being located in the transition between the great areas of savannah and the Amazonian seasonally dry forests. The five species all formed some polyspecific associations, which involved sharing the available food resource. Mixed groups were significantly more frequent and therefore possibly more important to Saimiri, which was not the case in relation to the other four species. Assemblages, defined as the presence in the same clumped resource, without coordinated activity, of ≤ 3 primate species, were recorded primarily in fruiting fig trees. I suggest that assemblages are impelled by food constraints, forcing cofeeding in large seasonal resources, highlighting the ecological importance of figs to these primates. Linear regression models show that the number of feeding bouts in each habitat type is positively related to the number of fruiting trees exploited, but the density of these fruit trees, diversity of plant species, tree height, and total basal area of each habitat type have no relationship to feeding.
96 citations
TL;DR: This paper presents a general approach to lexical choice that can handle multiple, interacting constraints, and focuses on the problem of floating constraints, semantic or pragmatic constraints that float, appearing at a variety of different syntactic ranks, often merged with other semantic constraints.
Abstract: Lexical choice is a computationally complex task, requiring a generation system to consider a potentially large number of mappings between concepts and words. Constraints that aid in determining which word is best come from a wide variety of sources, including syntax, semantics, pragmatics, the lexicon, and the underlying domain. Furthermore, in some situations, different constraints come into play early on, while in others, they apply much later. This makes it difficult to determine a systematic ordering in which to apply constraints. In this paper, we present a general approach to lexical choice that can handle multiple, interacting constraints. We focus on the problem of floating constraints, semantic or pragmatic constraints that float, appearing at a variety of different syntactic ranks, often merged with other semantic constraints. This means that multiple content units can be realized by a single surface element, and conversely, that a single content unit can be realized by a variety of surface elements. Our approach uses the Functional Unification Formalism (FUF) to represent a generation lexicon, allowing for declarative and compositional representation of individual constraints.
96 citations
TL;DR: In the clinic in Recife Brazil, the trust of patients has been gained through long-term caring relationships and the magnitude depth and profound implications of this disability both for men and women are discovered.
94 citations
TL;DR: Fluorideglasses are particularly attractive hosts because they can bebered, maintaining a high intensity of pumping light over along interaction length, and large RE concentrations can be incorporated easily into the host matrix.
Abstract: Fluorideglasses are particularly attractive hosts because they can befibered, maintaining a high intensity of pumping light over along interaction length, and large RE concentrations can beincorporated easily into the host matrix. Furthermore, one ofthe advantages of fluoride hosts is the low energy of its moreenergetic phonons, which reduces the probability of mul-tiphonon relaxation processes between the RE electroniclevels.Among the many fluoride compositions discovered, it wasfound recently that fluoroindate glasses may become one im-portant material for photonics applications. The vitreous re-gion in the system InF
93 citations
TL;DR: Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice and suggested that the antineoplasic effect is associated to the polysaccharide molecular weight.
Abstract: Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect.
85 citations
TL;DR: In this article, the relationship between secondary forest regrowth stage and SIR-C SAR data is assessed, for an area located near to the Tapajos National Forest, south of Para State, in the Amazon region.
TL;DR: It was showed that vitamin A treatment has no impact on the recovery from non-measles pneumonia, despite some suggestion that severely affected patients may benefit and the addition of vitamin A for treatment protocols for childhood pneumonia is not recommended for clinical cure.
Abstract: OBJECTIVE: To evaluate the impact on clinical recovery and severity of the addition of large doses of vitamin A to the standard treatment for childhood pneumonia. DESIGN: A randomised, double blind, placebo controlled trial. SETTING: Study children were recruited at a public hospital in Recife, north east Brazil, an area of marginal vitamin A deficiency. SUBJECTS: 472 children aged 6 to 59 months with clinical diagnosis of pneumonia. INTERVENTIONS: 200,000 IU (infants) or 400,000 IU (1-4 year olds) of vitamin A in oil or similar capsules of placebo divided into two daily oral doses, in addition to the standard treatment. MAIN OUTCOME MEASURES: Duration of the episode and incidence of adverse outcomes. RESULTS: The groups were similar with respect to overall duration of pneumonia and incidence of adverse outcomes. Children who received vitamin A, however, were less likely to have fever by day 3 (P = 0.008) and were 29% less likely to fail to respond to the first line antibiotic (P = 0.054). CONCLUSION: There was little evidence for an effect of vitamin A treatment on the immediate outcome of the pneumonia episode.
TL;DR: An impairment in the susceptibility to cortical SD in chronic epileptic rats is indicated suggesting modifications in cortical excitability in the pilocarpine model of epilepsy.
TL;DR: In this paper, a study of 46 criancas brasileiras of classe-media baixa found that a consciencia sintatica and um facilitador contribute principalmente to the aquisicao de regras ortograficas that envolvem analises morfo-sintaticas.
Abstract: Varios estudos tem demonstrado uma estreita conexao entre o desenvolvimento da consciencia fonologica e o dominio de escritas alfabeticas. Sabemos, entretanto, que estes sistemas de escrita nao sao fieis a sua base fonologica e que para dominar a ortografia e preciso conscientizar-se de outros niveis de estruturacao da lingua. Estudo recente, com criancas inglesas, sugerem que o desenvolvimento da consciencia sintatica facilita a aquisicao de regras ortograficas que envolvem analises morfo-sintaticas. O presente estudo investigou estas relacoes em 46 criancas brasileiras de classe-media baixa. As criancas foram avaliadas quanto ao desenvolvimento da consciencia metalinguistica no inicio da primeira serie e quanto a aquisicao da ortografia no final da primeira e da segunda series. Os resultados indicaram que a consciencia sintatica e um facilitador especifico da aquisicao de regras ortograficas que envolvem analises morfo-sintaticas, enquanto que a consciencia fonologica contribui principalmente para a aquisicao de regras de contexto grafo-fonico.
TL;DR: In practice, it was confirmed that dissolved oxygen does not constitute any detrimental effect on reactor treatment performance and the coexistence of anaerobic and aerobic bacteria in one single reactor is feasible and increases the potentials of new applications in wastewater treatment.
Abstract: The anaerobic treatment processes are considered to be well-established methods for the elimination of easily biodegradable organic matter from wastewaters. Some difficulties concerning certain wastewaters are related to the possible presence of dissolved oxygen. The common belief is that anaerobes are oxygen intolerant. Therefore, the common practice is to use sequencing anaerobic and aerobic steps in separate tanks. Enhanced treatment by polishing off the residual biodegradable oxygen demand from effluents of anaerobic reactors, or the biodegradation of recalcitrant wastewater pollutants, usually requires sequenced anaerobic and aerobic bacteria activities. However, the combined activity of both bacteria can also be obtained in a single reactor. Previous experiments with either pure or mixed cultures showed that anaerobes can tolerate oxygen to a certain extent. The oxygen toxicity to methanogens in anaerobic sludges was quantified in batch experiments, as well as in anaerobic reactors. The results showed that methanogens have a high tolerance to oxygen. In practice, it was confirmed that dissolved oxygen does not constitute any detrimental effect on reactor treatment performance. This means that the coexistence of anaerobic and aerobic bacteria in one single reactor is feasible and increases the potentials of new applications in wastewater treatment
TL;DR: The results indicate that short episodes of early malnutrition during the suckling period can affect body and brain development, as well as the cortical susceptibility to SD during adulthood, and suggest that the third week of lactation is the period during which the brain is most sensitive to malnutrition, concerning the effects on SD.
Abstract: Lactating rat dams were submitted to short episodes (1, 2 or 3 weeks) of nutritional restriction by receiving the “regional basic diet” (RBD, with 8% protein) of low-income human populations of Northeast Brazil. Their pups were then studied regarding the developmental effects on body and brain weights. When the rats reached adulthood, cortical susceptibility to the phenomenon of spreading depression (SD) was evaluated by performing electrophysiological recordings on the surface of the cerebral cortex. SD was elicited at 20-min intervals by applying 2% KCl for 1 min to a site on the frontal cortex and its occurrence was monitored at 2 sites in the parietal region by recording the electrocorticogram and the slow potential change of SD. When compared to control rats fed a commercial diet with 23% protein, early malnourished rats showed deficits in body and brain weights (10% to 60% and 3% to 15%, respectively), as well as increases in velocity of SD propagation (10% to 20%). These effects were directly related to the duration of maternal dietary restriction, with pups malnourished for 2 or 3 weeks presenting more intense weight and SD changes than those malnourished for 1 week. The effects of 1-week restrictions on SD were less evident in the pups malnourished during the second week of lactation and were more evident in pups receiving the RBD during the third week. The results indicate that short episodes of early malnutrition during the suckling period can affect body and brain development, as well as the cortical susceptibility to SD during adulthood. The data also suggest that the third week of lactation is the period during which the brain is most sensitive to malnutrition, concerning the effects on SD.
TL;DR: It is surmised that the early differential growth patterns are set in utero and are indirectly affected prenatally by socioeconomic status, and are strongly associated with attained z-scores at 12 months.
Abstract: Low birth weight has many adverse consequences, some of which might be ameliorated if there is good postnatal compensatory, or catch-up, growth. We monitored growth, morbidity and feeding patterns in a cohort of 133 full-term, low birth weight infants from poor families in Pernambuco, Brazil, and investigated the relative contributions of a number of socioeconomic, maternal and infant variables to postnatal growth. Growth was measured at 4, 8, 17, 26 and 52 wk of age. Differential growth patterns were most marked during the first 8 wk of life, and the gains in z-score during this interval were strongly associated with attained z-scores at 12 months (r = 0.62 for weight and 0.64 for length). In a multivariate model, socioeconomic variables explained 21.4% of the variation in maximum gain in weight-for-age z-score achieved during the 12-month period, maternal weight explained a further 4.4%, infant birth length 4.7% and neonatal illness 5.4%. For maximum gain in length-for-age z-score, socioeconomic variables accounted for 24.4% of the variance, maternal height 4.9%, maternal smoking 3.3% and neonatal illness 3.1%. We surmise that the early differential growth patterns are set in utero and are indirectly affected prenatally by socioeconomic status.
TL;DR: Alterations to the paepalantine structure are suggested to reduce its mutagenic and cytotoxic activity in investigations for its antineoplastic potential.
Abstract: A new isocoumarin with antimicrobial activity was isolated from Paepalanthus vellozioides (a native Brazilian plant) and called paepalantine. This study was carried out to assess the mutagenic activity of this new agent in assays with Salmonella typhimurium TA100, TA98, and TA102 and in Chinese hamster ovary (CHO) cell cultures, as well as cytotoxicity to McCoy cells. Paepalantine caused a significant dose-dependent increase in the frequency of revertants in the three strains used in the assay, both with and without S9 mix, in concentrations varying from 2 to 128 μg/plate. The mutagenicity was confirmed in assays with CHO cells treated in the G1, S, and G2 phases of the cell cycle. There was an increase in the chromosomal aberration frequency, mainly in the G2 phase. Furthermore, the mitotic index of the treated cultures (40, 80, and 160 μg/ml) was significantly lower, indicating cytotoxicity. The midpoint cytotoxicity values to McCoy cells by the neutral red (NR) and microculture tetrazolium (MTT) techniques resulted in a NR50 and MTT50 of 30 and 38 μg/ml, respectively. Alterations to the paepalantine structure are suggested to reduce its mutagenic and cytotoxic activity in investigations for its antineoplasic potential. Teratogenesis Carcinog. Mutagen. 17:85–95, 1997. © 1997 Wiley-Liss, Inc.
TL;DR: In this paper, Historias elaboradas por criancas of 6-7 anos foram analisadas em funcao de indicadores especificos agrupados em um sistema de analise.
Abstract: A coerencia e o processo responsavel pela formacao do sentido que garante a compreensibilidade de um texto. Investigacoes sobre o tema se caracterizam por: (a) um enfoque puramente linguistico, ficando em aberto questoes relacionadas ao desenvolvimento e aos fatores que o influenciam; e (b) examinar a coerencia estabelecida pelo receptor do texto, sendo raras as investigacoes que abordam a perspectiva do narrador. Em uma abordagem de desenvolvimento, o presente estudo examinou as possibilidades e dificuldades de criancas em estabelecer a coerencia ao produzir um texto. Historias elaboradas por criancas de 6-7 anos foram analisadas em funcao de indicadores especificos agrupados em um sistema de analise que expressa diferentes niveis no estabelecimento da coerencia. Observou-se que o desenvolvimento da coerencia se relaciona a aquisicao da leitura e da escrita. Criticas sao feitas quanto a ausencia de um sistema de analise que contribua para o exame da coerencia textual em criancas.
TL;DR: Two contiguous villages in Tracunhaém county, endemic for schistosomiasis, were studied: Itapinassu and São Joaquim and farming predominates in the former region while ceramics is the main activity in the latter.
Abstract: Two contiguous villages in Tracunhaem county (State of Pernambuco), endemic for schistosomiasis, were studied: Itapinassu (138 inhabitants) and Sao Joaquim (91 inhabitants). Agriculture predominates in the former region while ceramics is the main activity in the latter. Although no statistical difference was found regarding prevalence, severe infection (> 400 epg) predominated in Itapinassu, probably related to the kind of occupation. No association was found between parasite burden and severity of disease, in spite of the high infection rates for Schistosoma mansoni in both communities (approx. 60%). Typical epidemiological features of schistosomiasis such as age-related prevalences and intensities of infection (high in children, low in adults) were also mutual characteristics. Nutritional status determined through anthropometric evaluation was carried out by measuring specific anthropometric indicators. A deficit of energy intake, as well as vitamin A and riboflavin deficiencies were detected. The prevalence of moderate or severe undernutrition in patients under 18 years old was 21.9% in Itapinassu and 24.1% in Sao Joaquim. In this group an association was found between prevalence of schistosomiasis and chronic undernutrition. Similarly, for patients over 18 year old the prevalence of undernutrition was higher than 20%. However, in this case no association between nutritional status and either prevalence of schistosomiasis or parasite burden could be detected. The two communities had not been treated for eight years.
01 Jan 1997
TL;DR: Findings suggest that immobilized Cra lectin has the potential for use in studies both to isolate and to characterize certain serum glycoproteins.
TL;DR: In this article, the authors compared three neighboring sites representing different stages of a shifting cultivation cycle on a deeply weathered Oxisol on the Chapada de Araripe in the semiarid region of NE Brazil.
TL;DR: The karyological information supports the hypothesis that the Velloziaceae originated on the South American, rather than on the African continent.
Abstract: Chromosome number and other cytological features are reported from 35 species ofVelloziaceae, including several African and Brazilian populations. All analyzed species show areticulate interphase nuclei and prophase/prometaphase chromosomes with proximal early condensation. Most heteropycnotic blocks do not seem to correspond to heterochromatin since, at least inVellozia patens, they do not stain differentially after C-banding procedures. Regarding the chromosome number, three main groups could be identified. The first comprised diploid species of the generaNanuza, Vellozia and the Brazilian species ofXerophyta with 2n = 14 or 16; the second comprised tetraploid species with 2n = 34, and included all Brazilian species of subfam.Barbacenioideae; the third group, of hexaploid species, comprised the African representatives of the genusXerophyta. A single population ofVellozia, possibly of hybrid origin, had 2n ≅ 32. A basic number of x = 8 is proposed for the family. The karyological information supports the hypothesis that theVelloziaceae originated on the South American, rather than on the African continent.
TL;DR: This work describes the extraction and back-extraction of a lipase from crude extract of Penicillium citrinum using AOT reversed micelles in isooctane using a single protein band at 33000 Da for SDS–PAGE analysis for the recovered and purified enzyme.
Abstract: This work describes the extraction and back-extraction of a lipase from crude extract of Penicillium citrinum using AOT reversed micelles in isooctane. The effect of pH, ionic strength, AOT concentration on the protein forward and backward transfer at 20°C was studied. The maximum protein forward extraction (32·0%) was achieved at pH 4·0 with a 50 mmol dm−3 acetate buffer containing 100 mmol dm−3 KCl and 100 mmol dm−3 AOT in isooctane. Proteins were back-extracted (82·7%) to a new aqueous phase containing 100 mmol dm−3 pH 8·0 phosphate buffer and 1000 mmol dm−3 KCl. No enzyme activity could be detected either in the micellar phase or in the aqueous phase after protein back-extraction. However, the lipolytic activity was recovered after hydrophobic interaction chromatography on a Phenyl Superose column. The yield obtained for the overall process was 68% for activity, 26·4% for protein recovery and the purification factor was 810-fold. A single protein band at 33000 Da was obtained for SDS–PAGE analysis for the recovered and purified enzyme. © 1997 SCI.
01 Jan 1997
TL;DR: In this article, a detailed examination of a set of examples from Neoproterozoic belts of Brazil allows us to suggest that this interpretation is not unequivocal, and that pluton-enhanced strain localization and shear zone nucleation may represent alternative processes resulting in a close association of shear zones and plutons.
Abstract: The association of shear zones and magmatism is usually regarded as indicating that partial melting and/or melt transport and emplacement was favored by pre-existing shear zones. However, a detailed examination of a set of examples from Neoproterozoic belts of Brazil allows us to suggest that this interpretation is not unequivocal. In some cases, for instance dyke-swarms, dyke-like plutons and small elongated plutons, a large body of evidence supports shear zone-assisted melt emplacement. In other instances, and especially for large-scale plutons, demonstrative criteria for shear zones predating magma emplacement are lacking, or even support magma emplacement predating shear zone development. Either pluton-enhanced strain localization and shear zone nucleation, or coeval growth of shear zone and granite emplacement, may represent alternative processes resulting in a close association of shear zones and plutons.
TL;DR: The mitotic chromosomes of 51 citrus accessions from the Centro Nacional de Pesquisa em Mandioca e Fruticultura Tropical, Cruz das Almas, BA, Brazil, were analyzed and showed high variability in the number and position of secondary constrictions, indicating a high structural variability and heterozygosity of citrus germplasms.
Abstract: The mitotic chromosomes of 51 citrus accessions from the Centro Nacional de Pesquisa em Mandioca e Fruticultura Tropical, Cruz das Almas, BA, Brazil, were analyzed. The sample included representatives of 20 Citrus species, one of Poncirus and seven hybrids. All accessions showed 2n = 18 without any evidence of numerical variation. The most clearly variable karyotype feature was the number and position of secondary constrictions (SECs). In 19 accessions the SECs were not identified, mainly due to the degree of chromatin condensation. In the remainder they varied in number from one to three per karyotype. They were found in the proximal region of one of the three largest chromosome pairs, in the terminal/subterminal region of a smaller chromosome or, more seldom, terminally in a larger chromosome. Only in a few cases were such constrictions observed simultaneously in both homologues of the same chromosome pair. The high variability of this karyotype feature may be due to the activation of this region in the previous interphase but may also indicate a high structural variability and heterozygosity of citrus germplasms
TL;DR: In this article, a simple potential model was proposed to determine the carbon 1s electron binding energies determined by X-ray photoelectron spectroscopy and mean dipole moment derivatives obtained from experimental infrared intensities.
Abstract: Carbon 1s electron binding energies determined by X-ray photoelectron spectroscopy and mean dipole moment derivatives obtained from experimental infrared intensities are shown to be related through the simple potential model proposed by Siegbahn and collaborators. The sp3 carbon atoms in 13 halomethanes, 2 ethanes, 3 methylacetylenes, cyclopropane, and ethylene oxide have 1s energies, which, after correction for electrostatic potentials from neighboring atoms, are linearly related to the carbon mean dipole moment derivatives, presenting a slope of 15.50 ± 0.29 eV/e. The sp2 carbons of ethylene, three haloethylenes, and three carbonyl compounds also exhibit a linear relationship having a significantly different slope of 17.37 ± 0.87 eV/e. The sp carbon atoms in acetylenes, cyanides, CO, CS2, CO2, and OCS show a third linear relationship, with a slope of 18.90 ± 0.75 eV/e. These slopes are proportional to the inverse atomic radii of sp3, sp2, and sp carbon atoms and according to the simple potential equatio...
TL;DR: The reformatsky reaction of 2-bromo esters and carbonyl compounds in the presence of zinc can be carried out in concentrated aqueous salt solutions without any cosolvent as mentioned in this paper.
Abstract: The Reformatsky reaction of 2-bromo esters and carbonyl compounds in the presence of zinc can be carried out in concentrated aqueous salt solutions without any cosolvent. The reaction of bromoacetates is greatly enhanced by catalytic amounts of benzoyl peroxide or peracids and gives satisfactory yields with aromatic aldehydes. Preparative yields comparable to those of the traditional procedure are obtained with ethyl 2-bromoisobutyrate. This ester needs no catalyst and reacts even with saturated aldehydes and aromatic ketones, although in low yields. A radical chain mechanism, initiated by electron abstraction from the organometallic Reformatsky reagent, is proposed. Two nonchain pathways, involving radicals directly produced on the metal surface, may compete, especially in the case of secondary and tertiary halides.
TL;DR: In this article, the luminescence properties of Eu3+ in Ba2SiO4 sites and the presence of Ee3+-O2− associates are reported.