Understanding anomalous mobility of proteins on SDS‐PAGE with special reference to the highly acidic extracellular domains of human E‐ and N‐cadherins

During SDS‐PAGE experiments, proteins generally display electrophoretic mobility in keeping with their molecular weights; however, some proteins display anomalies in mobility. Here, we focus attention on the anomalies displayed by the highly acidic ～110 residues‐long, sequence‐homologous, structurally‐analogous, extracellular domains of human E‐ and N‐cadherin. We report that there is a strong correlation between the acidity of each domain and the degree of the anomaly that it displays. The anomaly is only seen if the ratio of the numbers of negatively‐charged and positively‐charged residues is equal to or greater than the value of 1.50. The degree of the anomaly rises in proportion with this NC:PC ratio. Greater‐than‐expected anomalies are observed for domains containing dense clusters of negatively charged residues. A simple explanation for these observations is that highly acidic domains electrostatically repel SDS. This results in insufficient SDS binding, insufficient electromotive incentive and (consequently) lowered electrophoretic mobility. This explanation is in consonance with the current view that initial stages of SDS‐protein engagement tend to be dominated by electrostatics. We discuss the current anomalies within the broader context of all conceivable explanations for such anomalies.     

Metallated Macrocyclic Derivatives as a Hole – Transporting Materials for Perovskite Solar Cells

Spiro‐OMeTAD is widely used as thehole‐transporting material (HTM) in perovskite solar cells (PSC), which extracts positive charges and protects the perovskite materials from metal electrode, setting a new world‐record efficiency of more than 20 %. Spiro‐OMeTAD layer engross moisture leading to the degradation of perovskite, and therefore, has poor air stability. It is also expensive therefore limiting scale‐up, so macrocyclic metal complex derivatives (MMDs) could be a suitable replacement. Our review covers low‐cost, high yield hydrophobic materials with minimal steps required for synthesis of efficient HTMs for planar/mesostructured PSCs. The MMDs based devices demonstrated PCEs around 19 % and showed stability for a longer duration, indicating that MMDs are a promising alternative to spiro‐OMeTAD and also easy to scale‐up via solution approach. Additionally, this review describes how optical and electrical properties of MMDs change with chemical structure, allowing for the design of novel hole‐mobility materials to achieve negligible hysteresis and act as effective functional barriers against moisture which results in a significant increase in the stability of the device. We provide an overview of the apt green‐synthesis, characterization, stability and implementation of the various classes of macrocyclic metal complex derivatives as HTM for photovoltaic applications.     

Structures of Stoichiometric Sodium Oxide Cluster Cations Studied by Ion Mobility Mass Spectrometry

Structures of stable compositions of sodium oxide cluster cations (Na_nO_m⁺,n≤11) have been investigated by ion mobility mass spectrometry. Stoichiometric compositions series, Na(Na₂O)_(n-1)/2⁺ (n=3, 5, 7, 9, and 11), were observed as stable composition series, and NaO(Na₂O)_(n-1)/2⁺ series (n=5, 7, 9, and 11) were observed as secondary stable series in the mass spectra. To assign the structures of these cluster ion series, collision cross sections between the ions and helium buffer gas were determined experimentally from the ion mobility measurements. Theoretical collision cross sections were also calculated for optimized structures of these compositions. Finally, the structures of Na(Na₂O)_(n-1)/2⁺ and NaO(Na₂O)_(n-1)/2⁺ were assigned to those having similar structural frames for each n except for n=9. All bonds in the assigned structures of Na(Na₂O)_(n-1)/2⁺ were between sodium and oxygen. On the other hand, there was one O-O bond in addition to Na-O bonds in NaO(Na₂O)_(n-1)/2⁺. This result indicates that NaO(Na₂O)_(n-1)/2⁺ have a peroxide ion (O₂^2-) as a substitute for an oxide ion (O^2-) of Na(Na₂O)_(n-1)/2⁺. As a result, both stable series, Na(Na₂O)_(n-1)/2⁺ and NaO(Na₂O)_(n-1)/2⁺, are closed-shell compositions. These closed-shell characteristics have a strong influence on the stability of sodium oxide cluster cations.     

碳纳米管受限空间对共轭高分子聚(9,9-二辛基芴-2,7-二基)链段运动行为的影响

在纳米受限空间中,高分子往往会表现出与本体状态不同的性质,如异常的链段运动特性及晶相间转变行为等,这些性质对于研究和开发新型高分子材料具有重要的意义,因此针对受限环境下高分子的物理化学特性研究也一直是高分子界关注的焦点.本文通过化学气相沉积法制备垂直取向排列的多壁碳纳米管阵列,借助溶剂润湿–收缩法获得规整的高密度阵列结构,其取向排列的碳纳米管间隙形成了准一维的纳米受限空间,尺寸在5—50 nm尺度下可调.进一步将共轭高分子聚(9,9-二辛基芴-2,7-二基)(PFO)填充到碳管间隙的纳米空间中,制备PFO与取向多壁碳纳米管阵列复合膜.结果发现在碳纳米管形成的纳米受限空间中,PFO的链段热运动行为与本征态PFO薄膜相比受到了明显的抑制,不同晶型间转变速度大大减缓,提高了构象的热稳定性,同时取向排列的碳纳米管对PFO分子链取向排列分布具有明显的诱导作用,有利于获得高性能的PFO晶体.这种高密度取向排列的碳纳米管阵列结构未来可以用于制备优良发光性能及高稳定性的PFO光电器件.     

Carrier mobility and relaxation time in BiCuSeO

To obtain thermoelectric properties of materials, a constant relaxation time approximation is generally employed. By employing deformation potential theory, a derivation of relaxation time and carrier mobility of BiCuSeO system is proposed combining with density functional theory calculation. And the inter-valley scattering, acoustic phonon scattering and ionized impurity scattering were considered in the model. The calculated values of relaxation time and carrier mobility in BiCuSeO are in good agreement with the results of experiment. The results suggest that acoustic phonon scattering is in dominant and the constant relaxation time approximation is reasonable in lightly doped sample, and the ionized impurity scattering play a significant role in heavily doped system.     

Vacancy-defect scattering in Ag(111)-supported silicene interface

The role of vacancy-defect scattering in electron mobility near the two-dimensional (2D) Ag(111)-supported silicene sheet interface was investigated in this paper. The interface structures of Ag(111)-supported silicene and silicene-sheet charge density were considered. Mobility limited by the vacancy-defect scattering was calculated in the order of 10²–10⁵ cm²/V?s, which was comparable with first-principle calculations and experimental results for free-standing and substrate-supported silicene. Results further showed the decay relationship between the electron mobility and vacancy density of silicene sheet. Furthermore, the influence of the Ag(111)-supported silicene sheet structure on electron mobility was confirmed through calculations. This study can contribute to the prediction of the electron mobility of other 2D graphene-like honeycomb-structure systems.     

基于锡组分和双轴张应力调控的临界带隙应变Ge_(1-x)Sn_x能带特性与迁移率计算

能带工程通过改变材料的能带结构可以显著提升其电学和光学性质,已广泛应用于半导体材料的改性研究.双轴张应力和Sn组分共同作用下的Ge_(1-x)Sn_x合金,不仅可以解决直接带隙转变所需高Sn组分带来的工艺难题,而且载流子迁移率会显著提升,在单片光电集成领域有很好的应用前景.根据形变势理论,分析了(001)面双轴张应变Ge_(1-x)Sn_x的带隙转变条件,并给出了在带隙转变临界点Sn组分和双轴张应力的关系;采用8κ·p方法,得到了临界带隙双轴张应变Ge_(1-x)Sn_x在布里渊区中心点附近的能带结构,进而计算得到电子与空穴有效质量;基于载流子散射模型,计算了电子与空穴迁移率.计算结果表明:较低Sn组分和双轴张应力的组合即可得到直接带隙Ge_(1-x)Sn_x合金,且直接带隙宽度随着应力的增大而减小;临界带隙双轴张应变Ge_(1-x)Sn_x具有极高的电子迁移率,空穴迁移率在较小应力作用下即可显著提升.考虑工艺实现难度和材料性能两个方面,可以选择4%Sn组分与1.2 GPa双轴张应力或3%Sn组分与1.5 GPa双轴张应力的组合用于高速器件和光电器件的设计.     

Solution-processed WOx hole injection layer for efficient fluorescent blue organic light-emitting diode

Solution-processed tungsten oxide (s-WO_x) interfacial layer for efficient hole injection in fluorescent blue organic light-emitting diode (OLED) is demonstrated. The OLED using 2-methyl-9,10-bis(naphthalen-2-yl)anthracene (MADN) as emitter shows luminous efficiency of 3.3 cd/A, power efficiency of 2.5 lm/W and external quantum efficiency of 4.6% with Commission Internationale d'Eclairage (CIE) color coordinates of (0.154, 0.102). Using MADN doped 1-4-di-[4-(N,N-diphenyl)amino]styryl-benzene as emitter, luminous efficiency of 10.8 cd/A, power efficiency of 6.4 lm/W and external quantum efficiency of 7.2% with CIE color coordinates of (0.167, 0.283) are achieved. Atomic force microscopy and X-ray photoelectron spectroscopy show that s-WO_x features superior film morphology and non-stoichiometry with slight oxygen deficiency. Current-voltage characteristics and impedance spectroscopy analysis indicate that s-WO_x behaves slightly enhanced hole injection and accordingly contributes to improved device performance in comparison with conventional vacuum thermal evaporation WO_x. Our results pave an alternative way for broadening WO_x application with solution process and advancing fluorescent blue OLEDs.     

Monolayered semiconducting GeAsSe and SnSbTe with ultrahigh hole mobility

High carrier mobility and a direct semiconducting band gap are two key properties of materials for electronic device applications. Using first-principles calculations, we predict two types of two-dimensional semiconductors, ultrathin GeAsSe and SnSbTe nanosheets, with desirable electronic and optical properties. Both GeAsSe and SnSbTe sheets are energetically favorable, with formation energies of −0.19 and −0.09 eV/atom, respectively, and have excellent dynamical and thermal stability, as determined by phonon dispersion calculations and Born–Oppenheimer molecular dynamics simulations. The relatively weak interlayer binding energies suggest that these monolayer sheets can be easily exfoliated from the bulk crystals. Importantly, monolayer GeAsSe and SnSbTe possess direct band gaps (2.56 and 1.96 eV, respectively) and superior hole mobility (~20 000 cm²·V⁻¹·s⁻¹), and both exhibit notable absorption in the visible region. A comparison of the band edge positions with the redox potentials of water reveals that layered GeAsSe and SnSbTe are potential photocatalysts for water splitting. These exceptional properties make layered GeAsSe and SnSbTe promising candidates for use in future high-speed electronic and optoelectronic devices.     

表面等离子体共振技术研究肝素对高迁移率族蛋白1与晚期糖基化终产物受体亲合力的影响

测定肝素与高迁移率族蛋1(HMGB1),及其与晚期糖基化终产物受体(RAGE)的亲和力,探讨肝素对HMGB1/RAGE亲和力的影响.用表面等离子体共振技术,实时分析肝素与HMGB1,HMGB1与RAGE的亲和常数,利用其binding analysis分析肝素对HMGB1/RAGE配受体结合的影响.肝素与HMGB1的动力学速率常数ka=1.78×105 L·(mol·s)-1,kd=8.02×10-4·s-1,亲和常数KA=2.22×108L·mol-1,KD=4.5×10-9 mol·L-1;HMGB1与RAGE的动力学常数ka=1.85×103L·(mol·s)-1,kd=1.81×10-4·s-1,亲和常数KA=1.02×107L·mol-1,KD=9.77×10-8mol·L-1.肝素与RAGE的亲和力极低.当浓度分别为50,100,1 000,10 000 U·L-1的肝素与HMGBl混合后,后者与RAGE的亲和力下降.上述不同浓度的肝素对HMGB1/RAGE亲和力的影响没有显著差异.结果表明,肝素可与HMGB1结合并影响后者与RAGE的亲和力,该作用并不与肝素浓度呈正相关.