Spontaneous spin polarization in rubrene studied by density functional theory calculations

We theoretically studied the spontaneous spin polarization properties of organic molecule rubrene by using density functional theory calculations. Our investigations show that normally nonmagnetic molecule rubrene could be spin polarized by spinless-hole injection. Magnetic moment of the molecule increases linearly with the extra hole charge amount only when the injected hole charges reach a certain value. The spin density resides predominantly on the carbon atoms in the tetracene backbone of rubrene molecule and also the bond lengths change differently due to the injected charge. Spontaneous spin polarization can be explained as the preferably filling of the spin-splitted carbon p_z orbitals near the Fermi energy for the injected charge.     

咔唑-苯并噻唑类衍生物薄膜的线性及非线性光学性质

以咔唑为电子供体,苯并噻唑为电子受体,合成了两种新型咔唑-苯并噻唑衍生物3-(2-苯并噻唑-2-基乙烯基)-N-乙基咔唑和3,6-二(2-苯并噻唑-2-基乙烯基)-N-乙基咔唑,通过核磁共振和分光光度计对其结构进行表征.利用刮刀法制备质量分数为4％的衍生物/聚酰亚胺的复合薄膜.采用透射光谱法和单光束Z-扫描技术分别测试了衍生物的线性和三阶非线性光学特性.Z扫描实验结果表明3-(2-苯并噻唑-2-基乙烯基)-N-乙基咔唑薄膜的非线性吸收系数和非线性折射系数分别为β1=-2.118 9×10-10 cm/W、r1=2.285 2×10-14 cm2/W,具有反饱和吸收特性和自聚焦效应;同时3,6-二(2-苯并噻唑-2-基乙烯基)-N-乙基咔唑薄膜的非线性吸收系数与非线性折射系数分别为β2=-1.275 6×10-9 cm/W、r2=-7.039 9×10-14 cm2/W,具有反饱和吸收特性和自散焦效应.     

2-(咪唑[1,2-a]吡啶-2-基)-2-氧代乙酸自由基及其高氯酸盐的晶体结构和磁性

报道2-(咪唑[1,2-a]吡啶-2-基)-2-氧代乙酸自由基及其高氯酸盐的晶体结构,探索了晶体堆积结构或超分子相互作用与磁性能的关系．在两个晶体结构中,超分子相互作用(氢键、原子间密接触、负离子-π电子或孤对-π)使2-(咪唑[1,2-a]吡啶-2-基)-2-氧代乙酸自由基主要以抗磁性的二聚体存在并导致了低的磁化率．该自由基晶体展示了准一维的柱状堆积链和弱的反铁磁性,而氢键和负离子-π作用则诱导高氯酸晶体呈一维双股链结构并显示了弱的铁磁性．     

Mercury in atmospheric aerosols: A preliminary case study for the city of Krakow,Poland

The level of contamination by mercury associated with airborne particulate matter in Krakow was determined. Samples of PM10 were collected on quartz filters using low-volume samplers. The total particulate mercury (TPM) concentrations in collected samples were determined by mercury analyser MA-3000 (Nippon Instruments Corporation). The reported results include also data on the carbonaceous aerosol and inorganic ions concentrations during the reported sampling campaign. The average concentration of the Total Particulate Mercury (TPM) in Krakow (Poland) was 0.22 ng·m⁻³ (during the period from 22 February to 2 March) and 0.49 ng·m⁻³ (on 3 March). A marked correlation between TPM and elemental carbon (EC) as well as with Cl^– was found. No significant association of the TPM with NO₃^– and SO₄^2– could be shown. The dry deposition flux of mercury was calculated as an average over the sampling period and was 47.3 ng·m⁻²·d⁻¹.     

Application of negligible and full depletion micro-extraction in environmental sciences

Negligible depletion micro-extraction (nd-ME) and full depletion micro-extraction (fd-ME) have been developed for specific purposes in environmental studies. Nd-ME is mainly designed to measure the free concentration and therefore evaluate the bioavailability of analytes in environmental matrices, and achieved by using large ratio of sample to extraction phase or extraction phase with low distribution coefficients for analytes. On the contrary, fd-ME is adopted to avoid matrix effects by determining the total amount of the analyte in the samples, and performed by using very low ratio of sample to extraction phase or extraction phase with extremely large distribution coefficients for analytes. In this review article, we highlight the basic concepts and applications of nd-ME and fd-ME in environmental sciences.     

The concept of in-situ vapor stripping for removing VOCs from groundwater

An in-situ remediation procedure is proposed to remove Volatile Organic Compounds (VOCs) dissolved in groundwater. This is accomplished by injecton of air into a well, using a combined technique of air-lift pumping with a form of vapor stripping. When air is injected into a well, it causes water to be lifted and forces groundwater flow towards the well, creating a recirculating cleanup zone. During this process, VOCs are transferred from the contaminated water to the rising air bubbles inside the well. The air bubbles are separated from the liquid near the top of the well, and the VOC vapor is collected and treated. In this system, water is not permitted to be lifted to the ground surface. Rather, the water is diverted into the unsaturated zone through a series of drains that are installed beneath the root-zone. The water then, free of a portion of VOCs, infiltrates back to the water table. As water continues to circulate, the VOC concentrations are gradually reduced.The feasibility of the proposed method was analyzed using concepts of mass transfer of VOCs from water to air-bubbles. Calculations indicate that the method has promise because equilibrium partitioning between the contaminated liquid and the gas bubbles is rapidly established.     

Unidirectional growth of l-asparagine monohydrate single crystal: First time observation of NLO nature and other studies of crystalline perfection,optical, mechanical and dielectric properties

L-asparagine monohydrate (LAM), a new amino acid single crystal, was grown by slow evaporation solution technique (SEST) as well as by recently invented Sankaranarayanan–Ramasamy (SR) method in aqueous medium. Using SR method, LAM single crystal of diameter ∼18 mm and length ∼52 mm was grown for the first time. The growth conditions were optimized and the maximum growth rate of 1.0 mm per day was observed for the SR crystal. The crystal structure was confirmed by powder XRD. The crystalline perfection was assessed by high resolution XRD and etching studies and found that the quality of the SR crystal is better than the SEST crystal. The UV–vis–NIR spectroscopic study revealed that the SR crystal has good optical transparency than that of SEST crystal. The relative second harmonic generation efficiency was measured and found to be ∼0.35 times to that of KDP. The laser damage threshold (LDT) was measured and found that the SR crystal has higher LDT value (5.76 GW cm⁻²) than SEST crystal (4.75 GW cm⁻²). The Vickers’s microhardness and dielectric studies were also carried out and discussed.     

Evaluation of the feasibility of the electronic tongue as a rapid analytical tool for wine age prediction and quantification of the organic acids and phenolic compounds. The case-study of Madeira wine

A set of fourteen Madeira wines comprising wines produced from four Vitis vinifera L. varieties (Bual, Malvasia, Verdelho and Tinta Negra Mole) that were 3, 6, 10 and 17 years old was analysed using HPLC and an electronic tongue (ET) multisensor system. Concentrations of 24 organic acids, phenolic and furanic compounds were determined by HPLC. The ET consisting of 26 potentiometric chemical sensors with plasticized PVC and chalcogenide glass membranes was used. Significance of the effects of age and variety on the ET response and wine composition with respect to the organic acids, phenolics and furanic derivatives were evaluated using ANOVA—Simultaneous Component Analysis (ASCA). Significance of the effects was estimated using a permutation test (1000 permutations). It was found that effects of age, grape variety and their interaction were significant for the HPLC data set and only the effect of age was significant for the ET data. Calibration models of the HPLC and ET data with respect to the wine age and of the ET data with respect to the concentration of the organic acids and phenolics were calculated using PLS1 regression. Models were validated using cross-validation. It was possible to predict wine age from HPLC and ET data with the accuracy in cross-validation of 2.6 and 1.8 years respectively. The ET was capable of detecting the following components (mean relative error in cross-validation is shown in the parentheses): tartaric (8%), citric (5%), formic (12%), protocatehuic (5%), vanillic (18%) and sinapic (14%) acids, catechin (6%), vanillin (12%) and trans-resveratrol (5%). The ET capability of predicting Madeira wine age with good accuracy (1.8 years) as well as quantify of some organic acids and phenolic compounds was demonstrated.     

Liquid–liquid equilibria of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate and sodium citrate/tartrate/acetate aqueous two-phase systems at 298.15 K: Experiment and correlation

Binodal curves of the aqueous 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄) + sodium citrate (Na₃C₆H₅O₇), [Bmim]BF₄ + sodium tartrate (Na₂C₄H₄O₆) and [Bmim]BF₄ + sodium acetate (NaC₂H₃O₂) systems have been determined experimentally at 298.15 K. The Merchuk equation was used to correlate the binodal data. The effective excluded volume (EEV) values obtained from the binodal model for these three systems were determined. The binodal curves and EEV both indicate that the salting-out abilities of the three salts follow the order: Na₃C₆H₅O₇ > Na₂C₄H₄O₆ > NaC₂H₃O₂. The liquid–liquid equilibrium (LLE) data were obtained by density determination and binodal curves correlation of these systems. Othmer–Tobias and Bancraft, and Setschenow equations were used for the correlation of the tie-line data. Good agreement was obtained with the experimental tie-line data with both models.     

Theoretical limit of energy consumption for removal of organic contaminants in U.S. EPA Priority Pollutant List by NRTL,UNIQUAC and Wilson models

This paper quantifies the theoretical limit of energy consumption for the removal of 20 representative organic contaminants (9 chlorinated alkyl hydrocarbons, 3 chlorinated alkenes, 3 brominated methanes, 5 aromatic hydrocarbons and their derivatives) in the United States Environmental Protection Agency (U.S. EPA) Priority Pollutant List by physical procedures. The general rules of the theoretical limit of energy consumption with different initial concentrations at 298.15 K and 1.01325 × 10⁵ Pa by NRTL, UNIQUAC and Wilson models are obtained from the thermodynamic analysis with our previously established method based on the thermodynamic first and second law. The results show that the waste treatment process needs a high energy consumption and the theoretical limit of energy consumption for organic contaminant removal increases with decreasing initial concentrations in aqueous solutions. The theoretical limit of energy consumption decreases with the more C–H bonds being replaced by C–Cl or C–Br bonds in chlorinated methanes, ethanes, ethenes or brominated methanes except for 1,1,2,2-tetrachloroethane, and the energy consumption for the removal of chlorinated methanes is higher than that of chlorinated ethanes with the same C–H bonds being replaced by C–Cl bonds. For the removal of chlorinated ethenes, brominated methanes and benzene and its derivatives studied, the energy consumption has corresponding relationship with solubility and the energy consumption is higher for the removal of organics with higher solubility.