Substrate effect on the melting temperature of thin polyethylene films

Strong dependence of the crystal orientation, morphology, and melting temperature (Tm) on the substrate is observed in the semicrystalline polyethylene thin films. The Tm decreases with the film thickness decrease when the film is thinner than a certain critical thickness, and the magnitude of the depression increases with increasing surface interaction. We attribute the large Tm depression to the decrease in the overall free energy on melting, which is caused by the substrate attraction force to the chains that competes against the interchain force which drives the chains to crystallization.     

Imprinted diffractive optics for terahertz radiation

Terahertz diffractive optic elements have been fabricated in polypropylene by imprinting with a silicon master. A silicon master is created with eight phase levels for high diffraction efficiency and etched using inductively coupled plasma reactive ion etching. This technique enables the rapid replication of complex optical structures in a high transmission material. Excellent replication of multilevel high efficiency Fresnel lenses is shown. The resulting lenses were tested with a 2 THz quantum cascade laser. The signal strength at the focus was 70 times the base signal strength.     

Sulphur isotope compositions of components of coal and S-isotope fractionation during its combustion and flue gas desulphurization

Sulphur isotope compositions were determined in two different Polish coals (hard coal and lignite) and by-products originating from their combustion. The desulphurization process was also investigated. It was demonstrated that desulphurization changes the isotopic composition of sulphur emitted in the form of SO(2) to the atmosphere even if the process is conducted in a different way (wet lime technology and electron beam method). This fact has to be considered in the studies regarding anthropogenic sulphur genesis and its fate in the environment.     

Polarizing beam splitter of a deep-etched fused-silica grating

We described a highly efficient polarizing beam splitter (PBS) of a deep-etched binary-phase fused-silica grating, where TE- and TM-polarized waves are mainly diffracted in the -1st and 0th orders, respectively. To achieve a high extinction ratio and diffraction efficiency, the grating depth and period are optimized by using rigorous coupled-wave analysis, which can be well explained based on the modal method with effective indices of the modes for TE/TM polarization. Holographic recording technology and inductively coupled plasma etching are employed to fabricate the fused-silica PBS grating. Experimental results of diffraction efficiencies approaching 80% for a TE-polarized wave in the -1st order and more than 85% for a TM-polarized wave in the 0th order were obtained at a wavelength of 1550 nm. Because of its compact structure and simple fabrication process, which is suitable for mass reproduction, a deep-etched fused-silica grating as a PBS should be a useful device for practical applications.     

Elliptic flow of charged particles in Pb-Pb collisions at sqrt[S(NN)] = 2.76 TeV

We report the first measurement of charged particle elliptic flow in Pb-Pb collisions at sqrt[S(NN)] =2.76 TeV with the ALICE detector at the CERN Large Hadron Collider. The measurement is performed in the central pseudorapidity region (|η|<0.8) and transverse momentum range 0.2

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Kinetics of ultrasound-assisted lipase-catalyzed glycerolysis of olive oil in solvent-free system

This work reports experimental kinetic data of solvent-free glycerolysis of olive oil using a commercial immobilized lipase (Novozym 435) under the influence of ultrasound irradiation. The experiments were performed in a mechanically stirred reactor under ultrasound irradiation, evaluating the effects of temperature (50-70 °C), enzyme concentration (2.5-10 wt%) and glycerol to oil molar ratio (0.8:1-3:1). Results show that ultrasound-assisted lipase-catalyzed glycerolysis might be a potential alternative route to conventional methods, as high contents of reaction products, especially monoglycerides, were achieved at mild irradiation power supply (∼130 W) and temperature, in a relatively short reaction time (2 h) and low enzyme content (7.5 wt%). To completeness, two simplified kinetic modeling approaches, based on the ordered-sequential bi bi mechanism and reaction stoichiometry, were employed to represent the experimental data, thus allowing a better understanding of the reaction kinetics.     

不同激发波长对Sr3Al2O6∶Eu2+,Dy3+红色长余辉发光材料发射光谱的影响

采用高温固相法合成了Sr3Al2O6∶Eu2+,Dy3+长余辉发光材料。用X射线衍射仪及荧光分光光度计对材料物相及光谱性能进行了分析。结果表明:所得样品为Sr3Al2O6的纯相,在360nm波长的激发下,得到波峰为537nm的宽带发射光谱;在468nm波长的激发下,得到波峰为590nm的宽带发射光谱;在波长为394nm的激发下,537和590nm的峰同时出现。根据晶格场效应和电子云膨胀效应,对不同激发波长对Sr3Al2O6∶Eu2+,Dy3+发射光谱的影响进行了解释。结果表明:在Sr3Al2O6∶Eu2+,Dy3+中发光中心因其5d能级劈裂幅度不同及4f65d1能带重心不同而导致发光颜色的不同。     

A CRITICAL STUDY ON THE INTERACTIONS OF HESPERITIN WITH HUMAN HEMOGLOBIN: FLUORESCENCE SPECTROSCOPIC AND MOLECULAR MODELING APPROACH

Hesperitin, a ubiquitous bioactive flavonoid abundant in citrus fruits is known to possess antioxidant, anti-carcinogenic, hypolipidemic, vasoprotective and other important therapeutic properties. Here we have explored the interactions of hesperitin with normal human hemoglobin (HbA), using steady state and time resolved fluorescence spectroscopy, far UV circular dicroism (CD) spectroscopy, combined with molecular modeling computations. Specific interaction of the flavonoid with HbA is confirmed from flavonoid-induced static quenching which is evident from steady state fluorescence as well as lifetime data. Both temperature dependent fluorescence measurements and molecular docking studies reveal that apart from hydrogen bonding and van der Waals interactions, electrostatic interactions also play crucial role in hesperitin-HbA interactions. Furthermore, electrostatic surface potential calculations indicate that the hesperitin binding site in HbA is intensely positive due to the presence of several lysine and histidine residues.     

氢化物发生—原子荧光法测定不同产地绞股蓝及其根际土壤中As,Hg,Se

通过优化了的氢化物发生—原子荧光法测定了7个省产绞股蓝及其根际土壤中As,Hg,Se三种元素的含量,研究结果表明:7个省产绞股蓝中As,Hg,Se的含量存在较大差异,但As和Hg两种重金属元素含量均低于《药用植物及制剂进出口绿色行业标准》中As和Hg的限量标准。Se元素含量同根际土壤中Se元素含量显示极显著相关性,故湖北恩施富硒区产绞股蓝中Se含量明显高于其他6省产绞股蓝。研究结果可以初步判定,绞股蓝中Se元素主要来源于土壤,而As和Hg元素的积累则不同于Se元素,还可能受到大气气溶胶的干、湿沉降等因素的影响。     

Full utilization of a mass spectrometer using on-demand sharing with multiple LC units

The applicability of liquid chromatography-mass spectrometry (LC/MS) is often limited by throughput. The sharing of a mass spectrometer with multiple LCs significantly improves throughput; however, the reported systems have not been designed to fully utilize the MS duty cycle, and as a result to achieve maximum throughput. To fully utilize the mass spectrometer, the number of LC units that a MS will need to recruit is application dependent and could be significantly larger than the current commercial or published implementations. For the example of a single analyte, the number may approach the peak capacity to a first degree approximation. Here, the construction of a MS system that flexibly recruits any number of LC units demanded by the application is discussed, followed by the method to port a previously developed LC/MS method to the system to fully utilize a mass spectrometer. To demonstrate the performance and operation, a prototypical MS system of eight LC units was constructed. When 1-min chromatographic separations were performed in parallel on the eight LCs of the system, the average LC/MS analysis time per sample was 10.5 s when applied to the analysis of samples in 384-well plate format. This system has been successfully used to conduct large-volume biochemical assays with the analysis of a variety of molecular entities in support of drug discovery efforts. Allowing the recruitment of the number of LC units appropriate for a given application, this system has the potential to be a plug-and-play system to fully utilize a mass spectrometer. Copyright ? 2012 John Wiley & Sons, Ltd.