Organotellurium(II) and -(IV) Compounds with Picolinoylbis(thioureas): From Simple 1 : 1 Adducts to Multimetallic Aggregates

Reactions of 2,6-dipicolinoylbis(N,N-diethylthiourea) (H2LEt) with common tellurium(IV) starting materials such as PhTeBr3 or TeBr4 yield various tellurium(IV) and tellurium(II) compounds depending on the conditions applied. Equimolar amounts of H2LEt and PhTeBr3 give the 1 : 1 complex [PhTeIVBr3(H2LEt)], while with an excess of H2LEt, the tellurium compound is partially reduced and a {PhTeII}+ building block coordinates to both sulfur atoms of H2LEt under the formation of the ion pair [PhTeII(H2LEt)][PhTeIVBr4]. Similar reactions between H2LEt and TeBr4 give the neutral monomer [TeIIBr2(H2LEt)] or the coordination polymer [TeIIBr2(H2LEt)]∞. The latter compound is also formed with the assistance of Pb2+ ions. While the lead ions do not appear in the isolated product, similar reactions with transition metal ions such as Ni2+, Mn2+, or Co2+ result in the formation of heterobimetallic complexes, in which Te(II) building blocks are directed to the sulfur atoms of the deprotonated ligand {H2LEt2-S,S}2−, while the transition metal ions occupy central coordination positions between two of the organic ligands using the pyridine nitrogen atom, carbonyl oxygen atom(s) and/or the nitrogen atoms of the thiourea units

Abelhas-sem-ferrão amazônicas defendem meliponários contra saques de outras abelhas

Entre as abelhas eussociais, dois gêneros apresentam estratégia de vida cleptobiótica, obtendo recursos alimentares de ninhos de outras abelhas ao invés de coletá-los em flores. Entre as espécies atacadas existe um gradiente de suscetibilidade ao roubo variando desde espécies vulneráveis até altamente resistentes. Neste trabalho nós descrevemos um ataque de Lestrimelitta rufipes a um ninho de Scaptotrigona sp. em um meliponário na Amazônia central (Amazonas, Brazil). O ninho atacado foi transferido para um meliponário com espécies resistentes (Duckeola ghilianii e Melipona fulva) e as interações foram descritas. As abelhas resistentes contra-atacaram e afugentaram as ladras protegendo o ninho de Scaptotrigona sp.. A presença de comportamento defensivo em gêneros não proximamente relacionados sugere que ele tenha evoluído mais de uma vez entre os Meliponini. Considerando o comportamento descrito, sugerimos a criação de espécies nativas resistentes em meliponários de regiões onde elas forem nativas, devido ao potencial que elas tem na proteção

Avaliação da produtividade da soja sob diferentes doses de Fósforo na região de Santarém - PA.

A agricultura no Brasil possui uma das maiores produções quando comparadas às principais potências mundiais no setor. As áreas agricultáveis e o próprio clima representam dentre outros fatores, um atrativo para qualificar o país como um grande produtor de alimentos e principalmente de grãos. A soja participa do Produto Interno Bruto (PIB) como um item de extrema importância na economia agrícola, inserindo diversos insumos, inerentes à qualidade de toda essa produção. Dentre os mais importantes, temos o Fósforo (P), que possui relevante papel no desenvolvimento e crescimento da soja, sendo foco de muitos estudos agronômicos relativos ao melhor manejo dos cultivos espalhados pelo Brasil. O presente trabalho aborda a utilização da adubação fosfatada na cultura da soja (FTS 4188) em diferentes dosagens, com o objetivo de avaliar a relação entre as doses aplicadas e a produtividade de grãos. Dessa forma o experimento foi realizado em blocos ao acaso, onde foram utilizados cinco tratamentos com diferentes dosagens de P2O5 sendo: 0 kg.ha-1 (Testemunha T1); 30 kg.ha-1 (T2); 60 kg.ha-1 (T3); 90 kg.ha-1 (T4) e 120 kg.ha-1 (T5) com quatro repetições. O experimento foi conduzido em Latossolo Amarelo e as dimensões das parcelas estudadas foram de 2,7 x 6,0 m. Uma vez verificada a produtividade de cada tratamento constatou-se que as médias dos dados não apresentaram diferença estatística significativa, sugerindo que em solos argilosos com altas concentrações de fósforo não existe a necessidade de adubaçã

General cognitive principles for learning structure in time and space

How are hierarchically structured sequences of objects, events or actions learned from experience and represented in the brain? When several streams of regularities present themselves, which will be learned and which ignored? Can statistical regularities take effect on their own, or are additional factors such as behavioral outcomes expected to influence statistical learning? Answers to these questions are starting to emerge through a convergence of findings from naturalistic observations, behavioral experiments, neurobiological studies, and computational analyses and simulations. We propose that a small set of principles are at work in every situation that involves learning of structure from patterns of experience and outline a general framework that accounts for such learning

Phase I trial of low dose N‐phosphonacetyl‐L‐aspartic acid and high dose 5‐fluorouracil administered concomitantly with radiation therapy for unresectable localized adenocarcinoma of the pancreas

Background. Preclinical and clinical data suggest that N‐phosphonacetyl‐L‐aspartic acid (PALA) can augment the cytotoxic effects of 5‐fluorouracil(5‐FU). In addition, the combination of 5‐FU and radiation therapy has been used with success in prolonging survival and providing palliation of symptoms in patients with advanced unresectable pancreatic carcinoma. This Phase I study was undertaken to determine the feasibility and evaluate the qualitative and quantitative toxicities of PALA and escalating doses of 5‐FU administered concomitantly with radiation therapy in patients with locally advanced nonmetastatic pancreatic adenocarcinoma. Methods. Ten previously untreated patients with advanced nonmetastatic adenocarcinoma of the pancreas were treated with 250 mg/m2 of PALA given as an intravenous bolus followed 24 hours later by 5‐FU, which was given by continuous hour infusion every week. The 5‐FU doses were assigned according to a Phase I drug escalation (1000 mg/m2, 1300 mg/m2, and 1700 mg/m2). Radiation therapy was delivered concurrently with chemotherapy at a dose of 180 cGy per fraction (900 cGy per week) over 6% weeks. PALA and 5‐FU were continued weekly after the end of radiation therapy, with disease assessments made every 8 weeks. Chemotherapy was continued until the disease progressed. Results. All 10 patients were evaluable. The maximum tolerated dose (MTD) of 5‐FU was 1300 mg/m2. Two of the four patients treated at the 1700 mg/m2 dose level experienced dose‐limiting toxicities, nausea/vomiting and mucositis, respectively. Toxicities were mild to moderate at the 1000 mg/m2 and 1300 mg/m2 dose levels. Two patients treated with 5‐FU at the 1300 mg/m2 dose level had complete responses, and one patient treated at the 1700 mg/m2 dose level had a partial response. The median survival was 12.5 months, and four patients survived more than 1 year. Conclusions. PALA and 5‐FU administered concomitantly with radiation therapy is an active regimen in locally advanced, unresectable pancreatic cancer. Doselimiting toxicities are nausea/vomiting and mucositis. The MTD of 5‐FU is 1300 mg/m2. The regimen is well tolerated and administered in an outpatient setting