Probing the Structure,Dynamics, and Bonding of Coinage Metal Complexes of White Phosphorus

A series of cationic white phosphorus complexes of the coinage metals Au and Cu have been synthesised and characterised both in the solid state and in solution. All complexes feature a P₄ unit coordinated through an edge P?P vector (η²‐like), although the degree of activation (as measured by the coordinated P?P bond length) is greater in the gold species. All of the cations are fluxional on the NMR timescale at room temperature, but in the case of the gold systems fluxionality is frozen out at ?90 °C. Electronic structure calculations suggest that this fluxionality proceeds via an η¹‐coordinated M?P₄ intermediate.     

Analytical techniques for wine analysis: An African perspective; a review

Analytical chemistry is playing an ever-increasingly important role in the global wine industry. Chemical analysis of wine is essential in ensuring product safety and conformity to regulatory laws governing the international market, as well as understanding the fundamental aspects of grape and wine production to improve manufacturing processes. Within this field, advanced instrumental analysis methods have been exploited more extensively in recent years. Important advances in instrumental analytical techniques have also found application in the wine industry. This review aims to highlight the most important developments in the field of instrumental wine and grape analysis in the African context. The focus of this overview is specifically on the application of advanced instrumental techniques, including spectroscopic and chromatographic methods. Recent developments in wine and grape analysis and their application in the African context are highlighted, and future trends are discussed in terms of their potential contribution to the industry.     

Generalized uncertainty principle and the maximum mass of ideal white dwarfs

The effects of a generalized uncertainty principle on the structure of an ideal white dwarf star is investigated. The equation describing the equilibrium configuration of the star is a generalized form of the Lane–Emden equation. It is proved that the star always has a finite size. It is then argued that the maximum mass of such an ideal white dwarf tends to infinity, as opposed to the conventional case where it has a finite value.     

Poly-albumen: Bio-derived structural polymer from polymerized egg white

Bio-derived materials could play an important role in future sustainable green and health technologies. This work reports the synthesis of a unique egg white-based bio-derived material showing excellent stiffness and ductility by polymerizing it with primary amine-based chemical compounds to form strong covalent bonds. As shown by both experiments and theoretical simulations, the amine-based molecules introduce strong bonds between amine ends and carboxylic ends of albumen amino acids resulting in an elastic modulus of ～4 GPa, a fracture strength of ～2 MPa and a high ductility of 40%. The distributed and interconnected network of interfaces between the hard albumen and the soft amine compounds gives the structure its unique combination of high stiffness and plasticity. A range of in-situ local and bulk mechanical tests as well as molecular dynamics (MD) simulations, reveal a significant interfacial stretching during deformation and a micro-crack diversion leading to an increased in ductility and toughness. The structure also shows a self-stiffening behavior under dynamic loading and a strength-induced aging suggesting adaptive mechanical behavior. This egg white-derived material could also be developed for bio-compatible and bio-medical applications.     

Energy harvesting of monostable Duffing oscillator under Gaussian white noise excitation

Energy harvesting of monostable Duffing oscillator with piezoelectric coupling under Gaussian white noise excitation is investigated. Based on the Fokker–Plank–Kolmogorov equation of piezoelectric coupling systems, the statistical moments of the response are derived from the Van Kampen expansion. The effects of the spectral density of the random excitation and the coefficient of cubic nonlinearity on the expected response moments are analyzed. Some numerical examples are presented to demonstrate the effects of excitation spectral density, coefficient of cubic nonlinearity and initial conditions on the output voltage.     

加性和乘性泊松白噪声联合激励下光滑非连续振子的随机响应

利用广义胞映射方法,研究了加性和乘性泊松白噪声联合作用下SD振子(smooth and discontinuous oscillator)的随机响应问题.基于图分析算法,获得确定SD振子的吸引子、吸引域、域边界、鞍和不变流形等全局特性.基于矩阵分析算法,计算了SD振子在泊松白噪声激励下的瞬态和稳态响应.结果表明:随机响应的概率密度函数演化方向和确定情况下的不稳定流形形状之间存在密切联系.蒙特卡罗模拟结果表明,所使用的方法是有效且准确的.     

Austrocolorone B and austrocolorin B1, cytotoxic anthracenone dimers from the Tasmanian mushroom Cortinarius vinosipes Gasparini

The yellow dihydroanthracenone dimer, austrocolorin B₁ and the unique violet-red 1,4-anthraquinone dimer, austrocolorone B, were isolated from the Tasmanian mushroom Cortinariusvinosipes and their structures and stereochemistry were determined from spectroscopic data. Austrocolorin B₁ and austrocolorone B were found to exhibit potent cytotoxic activity in vitro against the murine lymphoblast (P388D₁) cell line with IC₅₀ values in the range 10-31 μg/mL.     

固相萃取气相色谱-质谱法测定葡萄酒中118种农药残留量

样品(10g)先后用20mL及15mL乙腈超声波提取118种农药残留,经盐析并离心除水液液分配,所得提取液经40℃旋转蒸干,残渣溶于乙腈甲苯(3+1)混合溶液5mL中,溶液经Carb/PSA双层固相萃取小柱净化,淋出液蒸至近干并溶于丙酮-正己烷(1+1)混合溶液1.0mL中,供气相色谱质谱分析。分析中采用HP-5MS毛细管色谱柱及EI离子源和选择离子扫描方式,外标法定量。方法的测定下限(10S/N)在0.01～0.031mg·kg~(-1)之间,在加标水平为0.05mg·kg~(-1)时,方法回收率为67%～124%,相对标准偏差(n=5)小于12.2%。     

Simultaneous determination of active ingredients in blueberry wine by CE-AD

A method based on capillary electrophoresis coupled with amperometric detection（CE-AD） has been developed for the separation and determination of kaempferol,ferulic acid,vanillic acid,caffeic acid,gallic acid and protocatechuic acid in blueberry wine for the first time.In order to get the optimum conditions of separation,the effects of working electrode potential,pH value and concentration of running buffer,separation voltage and injection time on CE-AD were investigated.Under the optimum conditions, the analytes could be separated in Na₂B₄O₇-KH₂PO₄ buffer at pH 7.8 within 18 min.A 300μm diameter carbon disk electrode had good current responses at +0.95 V（vs.SCE） for all analytes.The responses were linear with concentrations over three orders of magnitude with detection limits（S/N = 3） at 10^-8 g/mL magnitude for the analytes and the recoveries were in the range of 95.8- 106.7%.The method could be successfully applied to the analysis of real sample with satisfactory results and therefore recommended for use by the quality control departments of fruit wine producers.     

小波变换-可见-近红外光谱技术用于鉴别品牌料酒的研究

模式识别技术广泛应用于食品种类、品牌和原产地的分类鉴别.本文测定了三个品牌114个料酒样品的可见-近红外光谱,利用小波变换技术对光谱信号进行了去噪和压缩处理,并采用Fisher权重法计算了16个小波细节系数的Fisher权重.以16个小波细节系数为特征变量采用向量相似度法对三种不同品牌料酒进行了相似度分析,主成分分析法...