Characterize the interaction between naringenin and bovine serum albumin using spectroscopic approach

Naringenin, a flavanone compound highly enriched in grapefruits, has been identified as a possible inhibitor of cell proliferation; and thus has the potential to act as an antitumorigenic agent. In this study, the binding of naringenin to bovine serum albumin (BSA) was studied at the physiological conditions (pH=7.40) by fluorescence and UV-vis spectroscopy. Naringenin strongly quenches the intrinsic fluorescence of BSA, and a decrease in the fluorescence quenching constant was observed together with an increase in temperature, which indicates that the fluorescence quenching of BSA by naringenin is a result of the formation of naringenin-BSA complex. Binding parameters calculating from Stern-Volmer method and Scatchard method showed that naringenin bind to BSA with the binding affinities of the order 10⁴ L mol⁻¹. Thermodynamic parameters such as ΔG, ΔH and ΔS, were calculated at different temperatures, showing that electrostatic interactions were mostly responsible for the binding of naringenin to BSA. Site marker competitive displacement experiments demonstrating that naringenin bind with high affinity to site I (subdomain IIA) of BSA. Furthermore, the effect of metal ions to naringenin-BSA system was studied, and the specific binding distance r (3.30 nm) between donor (Trp-212) and acceptor (naringenin) was obtained according to fluorescence resonance energy transfer (FRET).     

A combined experimental and theoretical analysis of Fe-implanted TiO2 modified by metal plasma ion implantation

Photocatalyst titanium dioxide (TiO₂) thin films were prepared using sol-gel process. To improve the photosensitivity of TiO₂ at visible light, transition metal of Fe was implanted into TiO₂ matrix at 20 keV using the metal plasma ion implantation process. The primary phase of the Fe-implanted TiO₂ films is anatase, but X-ray diffraction revealed a slight shift of diffraction peaks toward higher angles due to the substitutional doping of iron. The additional band gap energy levels were created due to the formation of the impurity levels (Fe-O) verified by X-ray photoelectron spectroscopy, which resulted in a shift of the absorption edge toward a longer wavelength in the absorption spectra. The optical band gap energy of TiO₂ films was reduced from 3.22 to 2.87 eV with an increase of Fe ion dosages from 0 to 1 × 10¹⁶ ions/cm². The band gap was determined by the Tauc plots. The photocatalysis efficiency of Fe-implanted TiO₂ was assessed using the degradation of methylene blue under ultraviolet and visible light irradiation. The calculated density of states for substitutional Fe-implanted TiO₂ was investigated using the first-principle calculations based on the density functional theory. A combined experimental and theoretical Fe-implanted TiO₂ film was formed, consistent with the experimentally observed photocatalysis efficiency of Fe-implanted TiO₂ in the visible region.     

Correlation between adsorption and thermal properties of lanthanide(III) dinicotinates

Structural and thermal properties of the two isostructural lanthanide metal-organic frameworks: [Er₂(pdc)₃(dmf)₂]·dmf (1) and [Tm₂(pdc)₃(dmf)₂]·dmf (2) where pdc = C₅H₃N(COO)₂²⁻ and dmf = N,N′-dimethylformamide, have been investigated. They are characterized by the BET surface area of 302 and 101 m²/g for 1 and 2, respectively. This paper deals with the influence of activation conditions on sorption properties of the investigated complexes. Thermal investigations of as-made and activated complexes point to their entirely different thermal decompositions.     

表面等离激元协助的方向性瑞利光散射研究

The origin of the Rayleigh scattering ring effect has been experimentally examined on a quantum dot/metal film system, in which CdTe quantum dots embedded in PVP are spin-coated on a thin Au film. On the basis of the angle-dependent, optical measurements under different excitation schemes (i.e., wavelength and polarization), we demonstrate that sur-face plasmon assisted directional radiation is responsible for such an effect. Moreover, an interesting phase-shift behavior is addressed.     

Towards molecular-scale electronics and biomolecular self-assembly

This paper provides an overview of recent research developments in the field of nanoelectronics with organic materials such as carbon nanotubes and DNA-templated nanowires. Carbon nanotubes and gold electrodes are chemically functionalized in order to contact carbon nanotubes by self-assembly. The transport properties of these nanotubes are dominated by charging effects and display clear Coulomb blockade behaviour. A different approach towards nanoscale electronics is based on the molecular recognition properties of biomolecules such as DNA. As an example, DNA is stretched between electrodes using a molecular combing technique. A two-step metallization procedure leads to the formation of highly conductive gold nanowires.     

利用三维荧光结合平行因子算法研究金属离子对溶解性有机物的猝灭和校正

溶解性有机物的荧光组份由于受到金属离子的影响其荧光强度受到变化,从而为溶解性有机物的定量分析带来挑战。利用三维荧光结合平行因子分析方法研究了Cu(Ⅱ), Fe(Ⅲ), Ni(Ⅱ), Sr(Ⅱ), Hg(Ⅱ), K(Ⅰ), Mg(Ⅱ) 和Mn(Ⅱ)八个金属离子对典型溶解性有机物荧光组分的荧光猝灭作用,五个水样来源各不相同。实验表明水样被平行因子成功分解为三个荧光组分(色氨酸、腐殖酸、富里酸),这三个荧光组份的荧光得分随着Fe(Ⅲ), Cu(Ⅱ), Hg (Ⅱ)和 Ni(Ⅱ)浓度的增加呈线性或指数下降。在这四种离子中,Fe(Ⅲ)和Cu(Ⅱ)对腐殖酸和富里酸的荧光猝灭作用明显大于Hg (Ⅱ)和 Ni(Ⅱ)。Sr(Ⅱ), K(Ⅰ), Mg(Ⅱ)和Mn(Ⅱ)基本没有影响。其中Fe(Ⅲ)对于三个荧光组分的荧光猝灭都有较好的分析。由于只考虑Fe(Ⅲ) 和Cu(Ⅱ)的影响,对于含有金属离子的饮用水的荧光强度的校正曲线也被建立。不同来源的饮用水中荧光组份的荧光得分的衰减规律也是不一样的,因此水样的来源也是测量时需要考虑的因素。实验证实了金属离子对溶解性有机物的荧光猝灭作用以及其他因素比如Fe(Ⅲ) 和Cu(Ⅱ)和溶解性有机物本身的多样性都是我们荧光测量典型荧光组份时需要考虑的。表明三维荧光结合平行因子分析方法是一个有效的准确测量溶解性有机物荧光组份的工具。     

原子吸收光谱法测定金属原子簇化合物中铬

报道了利用火焰原子吸收谱法测定金属原子簇化合物中铬,用钠离子消 除共存元素干扰,本法简便、快速,具有良好的准确度和精密度,相对标准偏差为0．60％－0．67％,回收率为100％－103％。     

直接溶样-火焰原子发射光谱法测定金属钠中的杂质钾

中国实验快堆（CEFR）选用金属钠做为冷却剂,其中杂质钾对它的热性能产生影响。为了核级钠中钾的含量,建立了直接溶样－火焰原子发射光谱法测定钠中的杂质钾的方法。实验中研究了超声波加湿溶样系统,优选了燃气（C2H2）、助燃气（Air)流量和燃烧器高度等工作参数,研究了酸效应、基体钠和共存元素的干扰效应。进行了高纯钠中加钾的回收实验,回收率在94．7％－109．8％之间,相对标准偏差为4．2％。本方法能够满足核级钠中杂质钾的分析要求,也适应于工业钠和高纯钠中钾的分析。     

The fundamental features and characteristics of discharge and plasma ion sources

An analysis of some of the fundamental and special physical processes occurring in discharge and plasma ion sources is presented.

The main purpose of the lecture is to present to the users of ion sources some key elements of information, of which not all may be generally recognised and which hopefully will be of value for a better understanding of the operational problems related to the complex behaviour of discharge and plasma ion sources.     

Carbon-13 NMR Spectra of Some Group VIIB Transition Metal Thiocarbonyl and Selenocarbonyl Complexes

Recently, we reported the discovery of the first examples of transition metal selenocarbonyl complexes, (n⁵-C₅H₅) Mn (CO)₂ (CSe) and (n⁶-C₆H₅CO₂CH₂(CO)₂ (CSe).¹ These complexes are particularly interesting because, unlike CO and CS, the diatomic CSe molecule has so far eluded isolation even at very low temperatures,² and so these complexes represent the stabilization of a chemically unstable species through coordination to a metal (cf. metal carbene complexes). We have also synthesized several thiocarbonyl complexes of the same type,^3,4 as well as the analogous rhenium selenocarbonyl complexes.⁴ While many detailed studies of the ¹³C nmr spectra of transition metal carbonyls have appeared in the literature over the past few years, there have been no such studies for the closely related thiocarbonyls and selenocarbonyls, although a few isolated data have been reported recently for metal thiocarbonyls.^5,6 In this communication, we report the ¹³C nmr spectra of the isoelectronic series of complexes, (n⁵-C₅H₄R) M(COI)₂ (CX) (M = Mn, R = H, CH₃; M = Re, R = H; X = O,S, Se).