Gas Phase Chemistry Of The 2-tert-butyl-3-phenylphosphirenylium Cation: Novel Onium Ions By Nucleophilic Attack At Phosphorus And De Novo P-spiro Bicyclic Phosphonium Ions Via [4 + 2+] Cycloaddition With Dienes

The 2-tert-butyl-3-phenylphosphirenylium ion 13 is formed in abundance in the gas phase from 1-chloro-1H-phosphirene 6 upon 70 eV electron ionization. Collision-induced dissociation (CID) and ion-molecule reactions followed by CID of the product ions were performed via pentaquadrupole mass spectrometry to probe the structure and reactivity of 13 towards representative nucleophiles and dienes. Under CID conditions, 13 produces a variety of fragment ions mainly via dissociation processes that are preceded by isomerizations. In ion-molecule reactions, 13 reacts readily with ethers, sulfides, pyridine and aniline to form hitherto unknown oxonium, sulfonium and azonium ions via nucleophilic attack at phosphorus. With butadiene, isoprene, 1-acetoxybutadiene, and with Danishefsky's diene (1-methoxy-3-silyloxybuta-1,3-diene), 13 undergoes [4 + 2+] cycloaddition at phosphorus to generate novel P-spiro bicyclic phosphonium ions. With butadiene and isoprene, a second [4 + 2] cycloaddition occurs which generates P-spiro tricyclic phosphonium ions. Whereas 13 also reacts readily with 1-acetoxybutadiene via [4 + 2+] cycloaddition, most of the nascent P-spiro cycloadducts are unstable and dissociate by the loss of either a neutral ketene or acetic acid molecule. B3LYP/6-31G(d,p) calculations were performed to gain insight into the structures of the product ions. The present study constitutes the first successful attempt to unravel the chemistry of 13, a unique 2π-Hückel phosphirenylium ion for which no direct solution chemical reactivity data are as yet available. The present findings also create a parallel with the solution reactivity of 1-halo-1H-phosphirenes and 1-triflato-1H-phosphirenes as precursors to phosphirenylium ions.12395400Laali, K.K., Geissler, B., Wagner, O., Hoffmann, J., Armbrust, R., Eisfeld, W., Regitz, M., (1994) J. Am. Chem. 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Analysis of coffee leaf rust epidemics with decision tree

A decision tree was developed to aid the understanding of coffee rust epidemics caused by Hemileia vastatrix. Infection rates calculated from monthly assessments of rust incidence were grouped into three classes: reduction or stagnation - TX1; moderate growth (up to 5pp) - TX2; and accelerated growth (above 5pp) - TX3. Meteorological data, expected yield and space between plants were used as explanatory variables for the infection rate classes. The decision tree was trained using 364 examples prepared from data collected in coffee-growing areas between October 1998 and October 2006. The model correctly classified 78% of the training data set and its accuracy was estimated at 73% for the classification of new examples. The success rates of the model were 88%, 57% and 79%, respectively, for the infection rate classes TX1, TX2 and TX3. The most important explanatory variables were mean temperature during leaf wetness periods, expected yield, mean of maximum temperatures during the incubation period and relative air humidity. The decision tree demonstrated its potential as a symbolic and interpretable model. Its model representation identified the existing decision boundaries in the data and the logic underlying them, helping to understand which variables, and interactions between these variables, led to coffee rust epidemics in the field.Uma árvore de decisão foi desenvolvida com o objetivo de auxiliar na compreensão de manifestações epidêmicas da ferrugem do cafeeiro causada por Hemileia vastatrix. Taxas de infecção calculadas a partir de avaliações mensais de incidência da ferrugem foram agrupadas em três classes: redução ou estagnação - TX1; crescimento moderado (até 5p.p.) - TX2; e crescimento acelerado (acima de 5p.p.)- TX3. Dados meteorológicos, carga pendente de frutos do cafeeiro (Coffea arabica) e espaçamento entre plantas foram usados como variáveis explicativas das classes de taxa de infecção. A árvore de decisão foi treinada com 364 exemplos preparados a partir de dados coletados em lavouras de café em produção, de outubro de 1998 a outubro de 2006. Ela classificou corretamente 78% do conjunto de treinamento e a sua acurácia foi estimada em 73% para a classificação de novos exemplos. O acerto do modelo foi de 88%, 57% e 79% dos exemplos, respectivamente, para as classes de taxa de infecção TX1, TX2 e TX3. As variáveis explicativas mais importantes foram a temperatura média nos períodos de molhamento foliar, a carga pendente de frutos, a média das temperaturas máximas diárias no período de incubação e a umidade relativa do ar. A árvore de decisão demonstrou seu potencial como modelo de representação simbólica e interpretável, permitindo a identificação das fronteiras de decisão existentes nos dados e da lógica contida neles, auxiliando na compreensão de quais variáveis e como as interações dessas variáveis conduziram as epidemias da ferrugem do cafeeiro no campo.11412

Caracterização da chuva horária em três locais do Estado de São Paulo: um subsídio ao planejamento de operações agrícolas de campo

This paper describes the rainfall pattern during the day along the different months of the year, calculated on an hourly basis for three sites: Campinas, Pindorama and Ubatuba, SP, Brazil, utilizing data series from 1957 to 1976. Results indicate that there is significative difference in the total of the hourly rainfall in the months of November to March in Campinas; October to April in Pindorama, and October to June in Ubatuba. Results of the hourly frequencies of rainfall are similar to those of total rainfall for Campinas and Pindorama. For Ubatuba, the hourly frequence of rainfall shows significant differences for all months of the year. During the mouths that show significant differences, the morning period is the most appropriate to realize agricultural practices, in which rainfall probability is reduced. During the months that do not show significant differences, the probability of rainfall occurrence is very reduced, less than 10%, in average, in all hours of the day, being possible to program agricultural practices during the whole period.Para caracterizar o comportamento das chuvas no decorrer do dia nos diferentes meses do ano, foram calculadas as médias dos totais e das freqüências das chuvas horárias para três locais: Campinas, Pindorama e Ubatuba, no período de 1957 a 1976. Os resultados obtidos mostram que existe diferença significativa no total de chuva horária nos meses de: novembro a março em Campinas; outubro a abril em Pindorama, e outubro a junho em Ubatuba. A freqüência horária das chuvas apresentou resultados semelhantes aos do total de chuva para Campinas e Pindorama. Em Ubatuba, a freqüência horária das chuvas apresentou diferença significativa durante todos os meses do ano. Durante os meses que apresentam diferenças significativas, o período da manhã mostra ser o mais conveniente para a realização das atividades agrícolas, onde são reduzidas as probabilidades de chover. Durante os meses que não apresentaram diferença significativa, a probabilidade de ocorrência de chuvas é pequena, inferior a 10%, em todos os horários do dia, sendo possível programar operações de campo durante todo o período

Excess adiposity and low physical fitness hamper Supine-to-Stand test performance among sedentary adolescents

Objective: The aim of this study was to analyze the relationship between body adiposity and physical fitness with performance in the Supine-to-Stand test (STS-test) in sedentary adolescents. Methods: Sixty-two adolescents, of both sexes, between 10 and 16 years old, participated in the study. Body mass (BM), height, waist circumference (WC), fat mass (FM), fat-free mass (FFM), right and left handgrip strength (HGS-right, HGS-left), abdominal resistance (ABDO), flexibility (FLEX), and cardiorespiratory fitness (VO2peak) were measured. Body mass index (BMI), z-score BMI (BMI-z), tri-ponderal mass index (TMI) and waist-to-height ratio (WHtR) were calculated. The STS-test was applied to evaluate the STS-MC by the movement patterns in the execution of the test. The STS-time in seconds (s) was categorized into terciles: fast (FG  2.6 s). One-way ANOVA, Chi-square, Spearman's correlation coefficient as well as non-parametric tests were used, with significance p ≤ 0.05. Results: The SG presented higher BMI, BMI-z, TMI, WHtR, FM, %FM, as well as lower averages for %FFM, HGS-right, HGS-left, FLEX, ABDO, VO2peak, VO2peak relative to BM (VO2peakBM) in relation to GF. The BMI, BMI-z, TMI, WC, WHtR and FM showed moderate and direct correlations with STS-time and inverse with STS-MC (p < 0.01). HGS-right, HGS-left, ABDO, and VO2peakBM showed moderate and an inverse correlation with STS-time (p < 0.05). The VO2peakBM was moderate and with direct correlations to STS-MC (p < 0.01). Conclusion: It is concluded that excess fat and low physical fitness hamper STS-test performance. Therefore, the STS-test can be used for screening students to assess MC

Growth inhibitory effects of 3′-nitro-3-phenylamino nor-beta-lapachone against HL-60: A redox-dependent mechanism

AbstractIn this study, the cytotoxicity, genotoxicity and early ROS generation of 2,2-dimethyl-(3H)-3-(N-3′-nitrophenylamino)naphtho[1,2-b]furan-4,5-dione (QPhNO2) were investigated and compared with those of its precursor, nor-beta-lapachone (nor-beta), with the main goal of proposing a mechanism of antitumor action. The results were correlated with those obtained from electrochemical experiments held in protic (acetate buffer pH 4.5) and aprotic (DMF/TBABF4) media in the presence and absence of oxygen and with those from dsDNA biosensors and ssDNA in solution, which provided evidence of a positive interaction with DNA in the case of QPhNO2. QPhNO2 caused DNA fragmentation and mitochondrial depolarization and induced apoptosis/necrosis in HL-60 cells. Pre-treatment with N-acetyl-l-cysteine partially abolished the observed effects related to the QPhNO2 treatment, including those involving apoptosis induction, indicating a partially redox-dependent mechanism. These findings point to the potential use of the combination of pharmacology and electrochemistry in medicinal chemistry

Integrative overview of the herpetofauna from serra da mocidade, a granitic mountain range in northern Brazil

The Brazilian mountain ranges from the Guiana Shield highlands are largely unexplored, with an understudied herpetofauna. Here the amphibian and reptile species diversity of the remote Serra da Mocidade mountain range, located in extreme northern Brazil, is reported upon, and biogeographical affinities and taxonomic highlights are discussed. A 22-days expedition to this mountain range was undertaken during which specimens were sampled at four distinct altitudinal levels (600, 960, 1,060 and 1,365 m above sea level) using six complementary methods. Specimens were identified through an integrated approach that considered morphological, bioacoustical, and molecular analyses. Fifty-one species (23 amphibians and 28 reptiles) were found, a comparable richness to other mountain ranges in the region. The recorded assemblage showed a mixed compositional influence from assemblages typical of other mountain ranges and lowland forest habitats in the region. Most of the taxa occupying the Serra da Mocidade mountain range are typical of the Guiana Shield or widely distributed in the Amazon. Extensions of known distribution ranges and candidate undescribed taxa are also recorded. This is the first herpetofaunal expedition that accessed the higher altitudinal levels of this mountain range, contributing to the basic knowledge of these groups in remote areas. © Leandro J.C.L. Moraes et al