Fruit tree model for uptake of organic compounds from soil

Apples and other fruits are frequently cultivated in gardens and are part of our daily diet. Uptake of pollutants into apples may therefore contribute to the human daily intake of toxic substances. In current risk assessment of polluted soils, regressions or models are in use, which were not intended to be used for tree fruits. A simple model for uptake of neutral organic contaminants into fruits is developed. It considers xylem and phloem transport to fruits through the stem. The mass balance is solved for the steady-state, and an example calculation is given. The Fruit Tree Model is compared to the empirical equation of Travis and Arms (T&A), and to results from fruits, collected in contaminated areas. For polar compounds, both T&A and the Fruit Tree Model predict bioconcentration factors fruit to soil (BCF, wet weight based) of >1. No empirical data are available to support this prediction. For very lipophilic compounds (log K OW >5), T&A overestimates the uptake. The conclusion from the Fruit Tree Model is that the transfer of lipophilic compounds into fruits is not relevant. This was also found by an empirical study with PCDD/F. According to the Fruit Tree Model, polar chemicals are transferred efficiently into fruits, but empirical data to verify these predictions are lacking.     

离子声等离子体波的动力屏蔽

本文讨论了离子声等离子体波的激发条件和它们对荷电粒子间相互作用势的动力屏蔽效应.对一些具有两个未完全被充满的外层电子能带的金属,计算了这种屏蔽效应,并研究了此动力效应对金属钯中氘-氘聚变反应率的影响.     

Pentafluorophenylchlorine(III) difluoride

Pentafluorophenylchlorine(III) difluoride has been prepared by the oxidation of pentafluorophenyl chloride at 117°C with elemental fluorine.     

Rotational analysis of bands in the high-resolution infrared spectra of cis,cis- and trans,trans-1,4-difluorobutadiene-2-d1

Pure samples of cis,cis- and trans,trans-1,4-difluorobutadiene-2-d₁ have been synthesized, and high-resolution (0.0015 cm^?1) infrared spectra have been recorded for these nonpolar molecules in the gas phase. For the cis,cis isomer, the rotational structure in two C-type bands at 775 and 666 cm^?1 and one A-type band at 866 cm^?1 has been analyzed to yield a combined set of 2020 ground state combination differences (GSCDs). Ground state rotational constants fit to these GSCDs are A₀ = 0.4195790(4), B₀ = 0.0536508(8), and C₀ = 0.0475802(9) cm^?1. For the trans,trans isomer, three C-type bands at 856, 839, and 709 cm^?1 have been investigated to give a combined set of 1624 GSCDs. Resulting ground state rotational constants for this isomer are A₀ = 0.9390117(8), B₀ = 0.0389225(4), and C₀ = 0.0373778(3) cm^?1. Small inertial defects confirm the planarity of both isomers in the ground state. Upper state rotational constants have been determined for most of the transitions. The ground state rotational constants for the two isotopologues will contribute to the data set needed for determining semiexperimental equilibrium structures for the nonpolar isomers of 1,4-difluorobutadiene.     

8-羟基喹啉过渡金属配合物电子光谱和二阶非线性光学性质的 DFT研究

使用含时密度泛函理论(TDDFT)B3LYP方法计算了IB, IIB, VIIIB过渡金属与8-羟基喹啉络合(MQ)后, 配合物的电子光谱以及二阶非线性光学性质. 结果表明, 掺杂过渡金属后, 形成络合物的能隙值减小100～150 kJ/mol, 最大吸收波长红移150～200 nm左右. 电子从基态到激发态的跃迁主要为p→p*, n→p*跃迁, 属于LLCT, MLCT过程. IB的络合物MQ以及VIIIB的络合物MQ3表现出良好的非线性光学性质.     

The high-resolution, jet-cooled infrared spectrum of pentafluoroethane

The jet-cooled spectrum of pentafluoroethane (C₂HF₅) has been recorded between 1100 and 1325 cm⁻¹ at a resolution of 0.0022 cm⁻¹. A rotational temperature of approximately 10 K was achieved by expanding 50 Torr of C₂HF₅ in 500 Torr of helium. Transitions belonging to five different fundamental vibrations have been assigned and fit to a Watson Hamiltonian: the ν₃ band at 1309.880494(189) cm⁻¹, ν₄ at 1200.734645(67) cm⁻¹, ν₅ at 1142.78147(33) cm⁻¹, ν₁₃ at 1223.334098(115) cm⁻¹, and ν₁₄ at 1147.394185(163) cm⁻¹. The fit of the ν₄ band has an rms deviation of 0.000436 cm⁻¹ compared to the uncertainty in the experimental line position of 0.0002 cm⁻¹. Satisfactory fits were achieved for the other four bands (ν₃, ν₅, ν₁₃, ν₁₄) at this cold temperature, with most of the centrifugal distortion constants fixed at the ground state values. Joint fits with previous work were attempted for the ν₄ and ν₁₃, successfully in the former case and unsuccessfully in the latter.     

“下愚”最智 “上智”最愚

历代反动派总是宣扬孔老二“上智与下愚不移”的唯心论说教,把它作为“剥削有理”、“压迫有理”的根据。林彪这个地主资产阶级的代理人,为了篡党夺权,复辟资本主义,建立林家法西斯王朝,也鼓吹“上智下愚”的谬论。他把自己吹成“生而知之”的“天才”,以“至贵”、超人自居,污蔑劳动人民“愚昧”、“落后”,只会说“恭喜发财”,只能想“油盐酱醋柴”。     

The infrared spectrum of the ν1 band of SiD3H

High-resolution spectra of the ν₁ stretching band of SiD₃H were recorded and analyzed, yielding values for ground- and upper-state constants and the band center. For ²⁸SiD₃H, B₀ = 1.777482(14) and ν₁ = 2187.2070(17) cm^?1. Similar analyses were performed on the less abundant species ²⁹SiD₃H and ³⁰SiD₃H.