Cytochrome c–dimyristoylphosphatidylglycerol interactions studied by asymmetrical flow field-flow fractionation

Lipid membranes are well recognized ligands that bind peripheral and integral proteins in a specific manner and regulate their function. Cytochrome c (cyt c) is one of the partner peripheral protein that binds to the lipid membranes via electrostatic and hydrophobic interactions. In this study, asymmetrical flow field-flow fractionation (AsFlFFF) was used to compare the interactions of cyt c with the acidic phospholipid 1,2-dimyristoyl-sn-glycero-3-phospho-rac-glycerol (DMPG), oleic acid (OA), and sodium dodecyl sulfate (SDS). The influence of pH and the cyt c–lipid molar mass ratios were evaluated by monitoring the diffusion coefficients and particle diameter distributions obtained for the free and lipid-bound protein. The hydrodynamic particle diameter of cyt c (pI 10) was 4.1 nm at pH 11.4 and around 4.2 nm at pH 7.0 and 8.0. Standard molar mass marker proteins were used for calibration to obtain the molar masses of free cyt c and its complexes with lipids. AsFlFFF revealed the binding of cyt c to DMPG and to OA to be mainly electrostatic. In the absence of electrostatic interactions, minor complex formation occurred, possibly due to the extended lipid anchorage involving the hydrophobic cavity of cyt c and the hydrocarbon chains of DMPG or SDS. The possibility of the formation of the molten globule state of cyt c, induced by the interaction between cyt c and lipids, is discussed.Electronic Supplementary Material Supplementary material is available for this article at     

Real-time sensing and three-dimensional display of far outdoor scenes based on asymmetric integral imaging

A new asymmetric integral imaging (AII) system for real-time pickup and three-dimensional (3-D) display of far outdoor scenes based on dynamic-pixel-mapping (DPM) is proposed. DPM is a digital process to transform the elemental images captured with a lens array into the perspective-variant object images (POIs) whose structures are matched with those of display lenses, where the orders of pixels in each POI are reversely mapped, and then capture a set of virtual elemental images (EIs) at the specific depth planes from the back-propagated POIs. This DPM enables an asymmetrical use of pickup and display lens arrays, allowing the long-ranged pickup of far outdoor scenes and their resolution-enhanced 3-D reconstruction. Experiments with a pair of pickup and display lens arrays whose pitches and focal lengths are given by 7.5 mm, 30 mm and 1.2 mm, 8 mm, respectively, show that the effective pickup-range and resolution of the proposed system have been increased up to 6 m and 1600×1600 pixels, respectively, from 0.064 m and 480×480 pixels of the conventional systems employing the same pickup and display lens arrays. In addition, experiments with an implemented test bed confirms that the proposed system can provide real-time 3-D images in 25 frames per second.     

甲硫醛单分子热分解反应

采用不对称Ｅｃｋａｒｔ势模拟了甲硫醛单分子反应体系，计算了各反应条件下反应速率常数及活化能，所得结果与甲醛结果作了比较。     

Synthesis and characterization of two new asymmetrical branched amines and related Mn(II) and Ni(II) Schiff base complexes containing pyridine moieties: Crystal structures of Mn(II) and Ni(II) complexes and their antibacterial properties

Two new branched pentadentate amines (N₅), 3,7-bis(2-pyridylmethyl)-5,5-dimethyl-3,7-diazaheptane-1-amine (1) and 4,8-bis(2-pyridylmethyl)-6,6-dimethyl-4,8-diaza octane-1-amine (2) have been prepared. These have been used to synthesis two new Schiff base complexes containing a pyridine and 2-pyridylmethyl pendant arm, by template [1+1] condensation of pyridine-2-carbaldehyde with the amines in the presence of Mn(II) in methanol. Elemental and spectral results are used to characterize the complexes and their structures are confirmed by single crystal X-ray diffraction studies. The structure of MnL¹(ClO₄)₂ indicates that in the solid state the Mn(II) ion adopts a slightly distorted octahedral geometry. The crystal structure of [Ni(1)(MeCN)](ClO₄)₂ is also reported and exhibits a slightly distorted octahedral geometry. Also the synthesized complexes were screened for their antibacterial activity against Escherichia coli (Lio), Serratia marcescens (PTCC 1330), Staphylococcous aureus (ATCC 6633), and Proteus vulgaris (Lio) and results showed that the all complexes have antibacterial effects and [NiL¹](ClO₄)₂, [MnL²](ClO₄) and [MnL¹](ClO₄)₂ have more effective ones against E. coli.     

不对称半桥变换器的小信号建模与仿真研究

不对称半桥变换器利用自身的寄生器件实现了开关管的零电压操作,在不影响电路整体结构,以及不增加成本的前提下达到了很好的输入、输出特性。文章建立了该类变换器的小信号模型,进行了动态分析、仿真研究及补偿回路设计,并对整体的电路稳定性和几个关键的频率特性进行了研究。     

Effects of metal irises on the guided-mode properties in asymmetrical slab waveguides

The diffraction phenomenon caused by metal transverse irises placed into an asymmetrical slab waveguide is examined by using the integral equation method. We concentrate on the possibility of controlling the radiation characteristics of the structure by changing the irises positions and the slab waveguide asymmetry. The aperture electric-field distribution is expressed in terms of a finite series of Chebyshev polynomials. The dominant TE guided-mode reflection and transmission coefficients, the near-field distribution and the far-field radiation pattern are calculated, while numerical results are presented for several cases of asymmetrical slab waveguides and different irises’ positions.     

The asymmetrical fractional Fourier transforms and its optical implement

Compared with the symmetrical lens system, the structure which contains double cylindrical lenses is also the basic units of a complex system and implement practical asymmetrical fractional Fourier transforms. Based on the theory of scalar diffraction and on the Fourier optics, we implement several kinds of asymmetrical fractional Fourier transforms and make the different mathematical manipulation at the corresponding coordinates, while the symmetrical system cannot. Meanwhile, the simulation experiment shows that such system not only makes the two perpendicular coordinates to be independently operated, but also increases the flexibility of the optical setup. All these characteristics make it flexible to application domain in optics.     

Synthesis, structure and magnetism of a S-shaped multi-iron substituted arsenotungstate containing a trivacant Keggin [B-α-AsW9O34] and a hexavacant Keggin [α-AsW6O26] fragments

A S-shaped multi-iron substituted arsenotungstate [enH₂]₂[(α-H₂As^VW₆O₂₆)Fe₃(H₂O)(B-α-H₄As^VW₉O₃₄)]₂[Fe]₂·8H₂O (1) (en=ethylenediamine) has been prepared by reaction of K₁₄[As₂^IIIW₁₉O₆₇(H₂O)]·nH₂O with Fe₂(SO₄)₃·xH₂O under hydrothermal conditions and structurally characterized by elemental analyses, IR spectra, UV spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. The skeleton of 1 consists of two asymmetric sandwich-type subunits [(α-H₂As^VW₆O₂₆)Fe₃(H₂O)(B-α-H₄As^VW₉O₃₄)]⁵⁻ linked by a di-Fe^III cluster. Moreover, magnetic susceptibility measurements demonstrate that 1 indicates the antiferromagnetic coupling interactions within Fe^III centers with the best-fitting set of parameters of J₁=−7.07 cm⁻¹, J₂=−0.45 cm⁻¹ and g=2.05, which are generated by the addition of the expressions of the molar susceptibilities of two tri-Fe^III clusters and one di-Fe^III cluster derived from for spin pairs coupled through the isotropic exchange interactions.     

Dynamic extension problems concerning asymmetrical mode III crack

By application of the method of complex variable function, dynamic extension problems on the surfaces of asymmetrical mode III crack subjected to shear loads were researched. Universal expressions of analytical solutions were attained by the approaches of self-similar functions. The problems considered can be facilely transformed into Riemann–Hilbert problems in terms of this technique, and analytical solutions of the stress, the displacement and dynamic stress intensity factor under the actions of unlike loads P and Pt located at the origin of the coordinates respectively, were acquired. In the light of corresponding material properties, the variable rule of dynamic stress intensity factor was depicted very well. By those solutions gained and superposition principle, the solutions of discretionarily intricate problems can be obtained.