Immobilization of Escherichia coli for detection of phage T4 using surface plasmon resonance

Phage contamination is a very serious and unavoidable problem in modern fermentation industry.It is necessary to develop sensitive and rapid phage detection methods for the early detection of phage contamination.In the present work,a real-time,rapid,specific and quantitative phage T4 detection method based on surface plasmon resonance(SPR) technique has been introduced.Escherichia coli was immobilized onto the preformed MPA self-assembled monolayer(SAM) through the widely used EDC/NHS cross-linking reaction as the recognition element.The bacteria immobilization was verified efficiently through the electrochemical measurements and fluorescence microscopy observations.The specific adsorption was much stronger than the non-specific adsorption of phage T4 binding to the biosensor surface modified by E.coli,and the latter could be neglected.The detection sensitivity reached 1×10 7 PFU/mL within 10 min.Within the experimental phage concentrations,the linear correlation between the SPR response and the phage concentration was good.The results suggest that the SPR technique is a potentially powerful tool for the phage or other virus detections,as a label-free,real-time,and rapid method.     

不同提取方法对红茶提取物抗氧化活性影响的研究

采取沸水浴法、回流法、微波法及超声波法探讨信阳红茶和印度红茶的抗氧化性,通过测定吸光度利用Fenton反应表征提取物对羟自由基的清除率.不同的提取方法对红茶抗氧化活性有一定的影响,羟自由基的清除率与红茶的抗氧化活性成正比.结果表明:信阳红茶沸水浴法提取率较高,印度红茶超声波法提取率较高.     

Preparation of phosphorus-doped carbon nanospheres and their electrocatalytic performance for O2 reduction

Phosphorus-doped carbon nanospheres without any metal residues were synthesized and characterized.The results revealed that the doping phosphorus atoms could significantly improve the electrocatalytic activity of graphitic carbon for the oxygen-reduction reaction(ORR) both in acidic and alkaline media,and the materials exhibited high electrocatalytic activity,long-term stability,and excellent tolerance to crossover effects especially in alkaline media.Quantum mechanics calculations with the density functional theory demonstrated that the changes in charge density and energetic characteristics of frontier orbitals for the P-doped graphene sheet could facilitate the ORR.     

Computational Evidence for a New Type of η(2) -H(2) Complex: When Main-Group Elements Act in Concert To Emulate Transition Metals

A bit on the side: A computational study of the reaction between a diphosphinoborane and dihydrogen has shown that, in marked contrast to other FLP systems, the reaction involves a symmetric dihydrogen complex as an intermediate. Thorough analysis has revealed an unusual bonding situation, namely side-on coordination of H(2) to the central boron center and weak contacts with the peripheral donor phosphine groups.     

硼酸对赖氨酸盐酸盐在半胱氨酸自组装膜上晶体生长的影响

研究了利用半胱氨酸自组装膜对诱导L-赖氨酸盐酸盐晶体生长的影响。实验发现,赖氨酸盐酸盐优先在水溶液内而不是在自组装膜表面成核生长为晶体,这是首次发现自组装单层对赖氨酸盐酸盐的成核有抑制作用。对自组装单层上的成核机理进行了探讨,2种氨基酸正电荷间的排斥作用可能是自组装膜抑制赖氨酸盐酸盐成核的原因。在赖氨酸盐酸盐溶液中加入了等摩尔硼酸,XRD结果表明,硼酸晶体优先生长在自组装单层上。而析出后的硼酸晶体又加速促进了赖氨酸盐酸盐的结晶析出。扫描电子显微镜表征发现,加入硼酸后赖氨酸盐酸盐晶体的形貌发生了很大变化,由原来的块状变为针状。实验结果表明,加入硼酸,可以加速赖氨酸盐酸盐的晶体生长并可以调控晶体的形貌和取向。     

Adsorption and reduction reactions of anthraquinone derivatives on gold electrodes studied with electrochemical surface‐enhanced Raman spectroscopy

Electrochemical surface‐enhanced Raman spectroscopy (EC‐SERS), combined with cyclic voltammetry, and the density functional theoretical (DFT) method were used to investigate self‐assembled monolayer (SAM) adsorption and reduction processes. Here, we choose the system of interest, being thiolacetyl‐terminated 2‐phenylene ethynylene‐substituted anthraquinone molecule (2‐AQ) on gold electrodes in buffered aqueous and aprotic solutions. In the buffered aqueous solution, the results of cyclic voltammetry and EC‐SERS measurements, as well as DFT calculations, indicate that the adsorbed molecules pass through a two‐electron two‐proton reduction reaction with cathodic polarization. In particular, the latter two methods confirmed the structural changes of SAMs during the process of redox reaction, 2‐AQ + 2e + 2H⁺ → 2‐AQH₂, where 2‐AQ and 2‐AQH₂ are the oxidized and reduced forms, respectively. In aprotic solutions (acetonitile), a stepwise reaction mechanism was proposed on the basis of the results of EC‐SERS and DFT calculations. The first reduction peak should be a half reaction process 2‐AQ + e → 2‐AQ⁻, where 2‐AQ⁻ is a single electron reduced form. Compared with that of 2‐AQ SAMs in the buffered aqueous solution, the results of EC‐SERS and DFT calculations in aprotic solution suggested that the solvent effect significantly influences the redox process of 2‐AQ in electrochemical interfaces. Copyright © 2012 John Wiley & Sons, Ltd.     

从乌龟坐标在动态Vaidya黑洞上的推广谈起

从一类参数未定的一般形式的乌龟坐标变换出发, 找出了在动态Vaidya黑洞背景下能将波动方程化为标准形式且无发散的乌龟坐标所满足的条件. 结果表明, 以乌龟坐标变换为主要特征的Damour-Ruffini方法, 用来计算动态黑洞的Hawking辐射时, 只适用于事件视界, 无法应用于表观视界.     

利用广义不确定关系计算Reissner-Nordstrm-de Sitter黑洞的统计力学熵

利用广义不确定关系修正的态密度方程并采用Wentzel-Kramers-Brillouin(WKB)近似方法,计算了Reissner-Nordstrm-de Sitter(RNdS)黑洞时空中标量场的统计力学熵.结果表明,由这种方法得到的黑洞熵与它的内、外视界面积和宇宙视界面积之和成正比,这与采用其他方法所得的结果一致,从而揭示了黑洞熵与视界面积之间的内在联系,也进一步表明了黑洞熵是视界面上量子态的熵,是一种量子效应.     

Enantiomerically Pure Phosphaalkene–Oxazolines (PhAk‐Ox): Synthesis,Scope and Copolymerization with Styrene

The design of a synthetic route to a class of enantiomerically pure phosphaalkene–oxazolines (PhAk‐Ox) is presented. The condensation of a lithium silylphosphide and a ketone (the phospha‐Peterson reaction) was used as the P?C bond‐forming step. Attempted condensation of PhC(?O)Ox (Ox=CNOCH(iPr)C H₂) and MesP(SiMe₃)Li gave the unusual heterocycle (MesP)₂C(Ph)?CN‐(S)‐CH(iPr)CH₂O ( 3 ). However, PhAk‐Ox (S,E)‐MesP?C(Ph)CMe₂Ox ( 1 a ) was successfully prepared by treating MesP(SiMe₃)Li with PhC(?O)CMe₂Ox (52 %). To demonstrate the modularity and tunability of the phospha‐Peterson synthesis several other phosphaalkene–oxazolines were prepared in an analogous manner to 1 a : TripP?C(Ph)CMe₂Ox ( 1 b ; Trip=2,4,6‐triisopropylphenyl), 2‐iPrC₆H₄P?C(Ph)CMe₂Ox ( 1 c ), 2‐tBuC₆H₄P?C(Ph)CMe₂Ox ( 1 d ), MesP?C(4‐MeOC₆H₄)CMe₂Ox ( 1 e ), MesP?C(Ph)C(CH₂)₄Ox ( 1 f ), and MesP?C(3,5‐(CF₃)₂C₆H₃)C(CH₂)₄Ox ( 1 g ). To evaluate the PhAk‐Ox compounds as prospective precursors to chiral phosphine polymers, monomer 1 a and styrene were subjected to radical‐initiated copolymerization conditions to afford [{MesPC(Ph)(CMe₂Ox)}_x{CH₂CHPh}_y]_n ( 9 a : x=0.13n, y=0.87n; GPC: M_w=7400 g mol^?1, PDI=1.15).