Ditopic Receptors Based on Dihomooxacalix[4]arenes Bearing Phenylurea Moieties With Electron-Withdrawing Groups for Anions and Organic Ion Pairs

Two bidentate dihomooxacalix[4]arene receptors bearing phenylurea moieties substituted with electron-withdrawing groups at the lower rim via a butyl spacer (CF3-Phurea 5b and NO2 Phurea 5c) were obtained in the cone conformation in solution, as shown by NMR. The X-ray crystal structure of 5b is reported. The binding affinity of these receptors toward several relevant anions was investigated by 1H NMR, UV-Vis absorption in different solvents, and fluorescence titrations. Compounds 5b and 5c were also tested as ditopic receptors for organic ion pairs, namely monoamine neurotransmitters and trace amine hydrochlorides by 1H NMR studies. The data showed that both receptors follow the same trend and, in comparison with the unsubstituted phenylurea 5a, they exhibit a significant enhancement on their host-guest properties, owing to the increased acidity of their urea NH protons. NO2-Phurea 5c is the best anion receptor, displaying the strongest complexation for F 12, closely followed by the oxoanions BzO 12, AcO 12, and HSO4-. Concerning ion pair recognition, both ditopic receptors presented an outstanding efficiency for the amine hydrochlorides, mainly 5c, with association constants higher than 109 M 122 in the case of phenylethylamine and tyramine

Conventional vs. Microwave-or mechanically-assisted synthesis of dihomooxacalix[4]arene phthalimides: NMR, X-ray and photophysical analysis

Direct O-alkylation of p-tert-butyldihomooxacalix[4]arene (1) with N-(bromopropyl)-or N-(bromoethyl)phthalimides and K2 CO3 in acetonitrile was conducted under conventional heating (reflux) and using microwave irradiation and ball milling methodologies. The reactions afforded mono-and mainly distal di-substituted derivatives in the cone conformation, in a total of eight compounds. They were isolated by column chromatography, and their conformations and the substitution patterns were established by NMR spectroscopy (1 H,13 C, COSY and NOESY experiments). The X-ray structures of four dihomooxacalix[4]arene phthalimide derivatives (2a, 3a, 3b and 5a) are reported, as well as their photophysical properties. The microwave (MW)-assisted alkylations drastically reduced the reaction times (from days to less than 45 min) and produced higher yields of both 1,3-di-substituted phthalimides (3a and 6a) with higher selectivity. Ball milling did not reveal to be a good method for this kind of reaction

Threading of Conformationally Stable Calix[6]arene Wheels Substituted at the Methylene Bridges

Calix[6]arenes disubstituted at the methylene bridges, which are stable in the cone or 1,2,3-alternate conformation, form pseudorotaxanes with dialkylammonium axles. The cone wheel-based pseudorotaxanes are 10-100 times more stable than those obtained with the native conformationally mobile calix[6]arene wheel, as a consequence of their higher degree of preorganization. The threading of conformationally stable 1,2,3-alternate calix[6]arenes is unprecedented in the literature. Therefore, very peculiar NMR features are here evidenced for this threading process involving the less symmetrical 1,2,3-alternate calix[6]arene conformation, which implies a peculiar rototranslation motion of the axle

An Inverse-Problem Approach to Designing Photonic Crystals for Cavity QED Experiments

Photonic band gap (PBG) materials are attractive for cavity QED experiments because they provide extremely small mode volumes and are monolithic, integratable structures. As such, PBG cavities are a promising alternative to Fabry-Perot resonators. However, the cavity requirements imposed by QED experiments, such as the need for high Q (low cavity damping) and small mode volumes, present significant design challenges for photonic band gap materials. Here, we pose the PBG design problem as a mathematical inversion and provide an analytical solution for a two-dimensional crystal. We then address a planar (2D crystal with finite thickness) structure using numerical techniques.Comment: 12 pages, 8 figures, preprint available from http://minty.caltech.edu/MabuchiLa

The effectiveness of the anti-CD11d treatment is reduced in rat models of spinal cord injury that produce significant levels of intraspinal hemorrhage

We have previously reported that administration of a CD11d monoclonal antibody (mAb) improves recovery in a clip-compression model of SCI. In this model the CD11d mAb reduces the infiltration of activated leukocytes into the injured spinal cord (as indicated by reduced intraspinal MPO). However not all anti-inflammatory strategies have reported beneficial results, suggesting that success of the CD11d mAb treatment may depend on the type or severity of the injury. We therefore tested the CD11d mAb treatment in a rat hemi-contusion model of cervical SCI. In contrast to its effects in the clip-compression model, the CD11d mAb treatment did not improve forelimb function nor did it significantly reduce MPO levels in the hemi-contused cord. To determine if the disparate results using the CD11d mAb were due to the biomechanical nature of the cord injury (compression SCI versus contusion SCI) or to the spinal level of the injury (12th thoracic level versus cervical) we further evaluated the CD11d mAb treatment after a T12 contusion SCI. In contrast to the T12 clip compression SCI, the CD11d mAb treatment did not improve locomotor recovery or significantly reduce MPO levels after T12 contusion SCI. Lesion analyses revealed increased levels of hemorrhage after contusion SCI compared to clip-compression SCI. SCI that is accompanied by increased intraspinal hemorrhage would be predicted to be refractory to the CD11d mAb therapy as this approach targets leukocyte diapedesis through the intact vasculature. These results suggest that the disparate results of the anti-CD11d treatment in contusion and clip-compression models of SCI are due to the different pathophysiological mechanisms that dominate these two types of spinal cord injuries

Characterizing the entanglement of symmetric many-particle spin-1/2 systems

Analyzing the properties of entanglement in many-particle spin-1/2 systems is generally difficult because the system's Hilbert space grows exponentially with the number of constituent particles, $N$. Fortunately, it is still possible to investigate many-particle entanglement when the state of the system possesses sufficient symmetry. In this paper, we present a practical method for efficiently computing various bipartite entanglement measures for states in the symmetric subspace and perform these calculations for $N\sim 10^3$. By considering all possible bipartite splits, we construct a picture of the multiscale entanglement in large symmetric systems. In particular, we characterize dynamically generated spin-squeezed states by comparing them to known reference states (e.g., GHZ and Dicke states) and new families of states with near-maximal bipartite entropy. We quantify the trade-off between the degree of entanglement and its robustness to particle loss, emphasizing that substantial entanglement need not be fragile.Comment: Updated version reflects changes made in January 200

Desempenho de genótipos de milho-verão para Rondônia e Mato Grosso: Rede Nacional - Ensaio Nacional de Cultivares Centro Super Precoce.

Objetivou-se com este trabalho determinar a resposta produtiva de genótipos de milho de ciclo curto

Características agronômicas de cultivares convencionais de soja de ciclo precoce e semiprecoce, avaliadas no Cone Sul de Rondônia, safra 2014/2015.

Com o objetivo de avaliar o desempenho de cultivares de soja convencional de ciclo precoce e semiprecoce, um experimento foi conduzido no campo experimental da Embrapa Rondônia, em Vilhena, na safra 2014/2015

Características agronômicas de híbridos de milho para safrinha, avaliadas no Cone Sul de Rondônia, safrinha 2014.

Com o objetivo de avaliar o desempenho de híbridos de milho na safrinha, um experimento foi conduzido no campo experimental da Embrapa Rondônia, em Vilhena, na safrinha 2014

Características agronômicas de cultivares convencionais de soja de ciclo médio, avaliadas no Cone Sul de Rondônia, safra 2014/2015.

Atualmente, o Brasil é o segundo maior produtor de soja do mundo, cultivando aproximadamente 96 milhões de toneladas do grão, em aproximadamente 32 milhões de hectares, o que resulta um rendimento médio de 2.999 kg.ha-¹. A expansão do cultivo de soja é uma oportunidade lucrativa para o produtor, diante da demanda do mercado externo, que exportou 50 milhões de toneladas na safra 2014/2015. Destacando-se como a cultura de maior importância econômica para Rondônia sendo o segundo maior produtor, cultivando uma área de 231,5 mil hectares, uma produção estimada de 732,9 mil toneladas com produtividade média de 3.166 k.ha-¹. Com objetivo de avaliar o desempenho de cultivares de soja de ciclo médio, o experimento foi conduzido no campo experimental da Embrapa Rondônia, em Vilhena, na safra 2014/2015. O experimento foi semeado em 06/11/2014 em blocos casualizados com quatro tratamentos e quatro repetições. A parcela experimental era constituída de quatro linhas de cinco metros de comprimento, espaçadas em 0,48 m entre linhas, sendo a parcela útil constituída por duas linhas centrais de 4 m. Para obtenção de dados de rendimento foram avaliadas as cultivares: BRSGO 8360, BRS 8381, CD 246 e AN 8500. As características avaliadas foram: dias para floração e maturação, altura da planta e, acamamento, peso de 100 grãos e rendimento em kg.ha-1 . O número de dias para a floração das cultivares variou de 38 a 42 dias; a maturação variou de 113 a 118, a altura de plantas variou de 42 cm a 71 cm e o peso de 100 grãos de 11,8 g a 19,4 g. A média de rendimento do ensaio foi satisfatória, de 4.008,6 kg.ha-1 , variando de 3.545,2 kg.ha-1 a 4.467,9 kg.ha-1 . Foram realizadas análises de variância e teste de comparação de médias utilizando o Programa Genes. De acordo com os resultados obtidos nas análises de variâncias, houve diferença significativa entre os tratamentos para todas as características avaliadas, exceto para acamamento e rendimento de grãos. No entanto todas as cultivares estão em fase de extensão para o cultivo no Estado de Rondônia, são excelentes opções para o produtor que deseja realizar a antecipação de semeadura, pois além de apresentarem ciclo médio de 115 dias, possibilitam a semeadura da segunda safra