Dendrimer as nanocarrier for drug delivery

Dendrimers are novel three dimensional, hyperbranched globular nanopolymeric architectures. Attractive features like nanoscopic size, narrow polydispersity index, excellent control over molecular structure, availability of multiple functional groups at the periphery and cavities in the interior distinguish them amongst the available polymers. Applications of dendrimers in a large variety of fields have been explored. Drug delivery scientists are especially enthusiastic about possible utility of dendrimers as drug delivery tool. Terminal functionalities provide a platform for conjugation of the drug and targeting moieties. In addition, these peripheral functional groups can be employed to tailor-make the properties of dendrimers, enhancing their versatility. The present review highlights the contribution of dendrimers in the field of nanotechnology with intent to aid the researchers in exploring dendrimers in the field of drug delivery.     

第二过渡周期金属单氧化物电子结构的DFT表征

文章采用九种密度泛函方法系统地研究了第二过渡周期金属单氧化物及其正负离子的键长,频率,电离能,电子亲和势及解离能。     

不同60Coγ剂量率下10位双极D/A转换器的总剂量效应

为探索电离辐射对数模混合电路的影响，对国产10位双极D/A转换器在60Coγ射线不同剂量率辐照下的电离辐射效应及退火特性进行研究。结果表明：D/A转换器对辐照剂量率十分敏感，在大剂量率辐照时，电路功能正常，各功能参数变化较小;在低剂量率辐照下，各参数变化显著，电路功能出现异常，表现出明显的低剂量率损伤增强效应。最后，结合空间电荷模型对其电离辐射损伤机理进行了初步探讨。     

Quantitation of lysinoalanine in dairy products by liquid chromatography–mass spectrometry with selective ion monitoring

The unnatural amino acid lysinoalanine (LAL) has been identified in milk and cheese products by liquid chromatography mass spectrometry (LC/ESI/MS) with selective ion monitoring (SIM) of the 9-fluorenyl-methylchloro-formate (FMOC) derivative. LAL is not present in raw milk or derived from Mozzarella cheese; however, high amounts of LAL are found in calcium caseinate and milk powder. As expected, milk fortified with caseinate or whey protein powder produces cheese with higher LAL content. Our analytical procedure is based on the simultaneous detection of specific ion masses of the FMOC–LAL derivative and the N-ε-methyl-lysine internal standard. A linear relationship was observed within the 0.2–20 ppm concentration range, in addition to a high correlation coefficient and ∼3% relative standard deviation.     

Purification and structural characterisation of lipid transfer protein from red wine and grapes

Lipid transfer proteins (LTP) play a major role in plant defence and are of particular interest due to their known ability to cause allergic reactions. These proteins are expressed in grapes and also remain detectable after vinification, especially in red wine. However, it remains unknown whether the protein undergoes any changes during the vinification process. Here, we present a purification method for LTPs from Dornfelder grapes and wine. By liquid-chromatography–mass spectroscopy (LC–MS/MS) we identified LTPs from two different species (Vitis vinifera and Vitis aestivalis). Additionally, the purified LTPs were characterised using spectrometric methods, confirming their high purity and structural stability during vinification. We conclude that LTPs are resistant to the alcohol content (13.5 vol%), acidic milieu of wine and other ingredients present during the vinification process, indicating that the allergenic potential of grape LTP is not diminished by the vinification process.     

Quantification of the Alternaria mycotoxin tenuazonic acid in beer

Tenuazonic acid (TA) is a major water soluble Alternaria mycotoxin. In the present work, a method for the quantification of TA in beer by liquid chromatography–ion-trap multistage mass spectrometry after derivatization with 2,4-dinitrophenylhydrazine is described. The method is based on a rapid workup procedure and features a LOD of 2 μg/kg without preconcentration using 400 mg of sample. Validation was performed for a working range of 8–500 μg/kg.     

Reconstruction of Ionization Density Distribution in Hall Thruster Channel from Ion Energy Spectrum of Plasma Jet

Propellant ionization in the Hall thruster discharge channel is a significant process and has strong influence on the thruster＇s efficiency. In this work, the functional relation has been established between the ionization density distribution and the function of the ion energy distribution through the basic equations governing the ion flow in the Hall thruster channel and the method achieved for reconstructing the ionization density distribution inside the channel by ordinary plasma diagnosis of the potential distribution and ion energy spectrum of the plasma jet. The ionization density distributions of single and double charged ions in an ATON-thruster channel have been reconstructed according to the experimental data of the potential distribution along the axis of the channel and the ion energy spectrum of the plasma jet. The agreement between the calculation and experimental results of the percentage of double charged ions proves the validity of our method achieved in this work.     

微囊藻毒素的色谱保留行为与荷电状态的关系

研究了微囊藻毒素MCRR和MCLR两种变体的荷电状态和色谱保留行为随流动相pH的变化。结果表明。在实验pH范围内，MCRR的保留系数K随pH值的增加而单调增加，MCLR的K值则先增加后减小。2种MC荷电为零组分的比例8。随pH值的变化也有同样的规律，说明MC的色谱保留行为与其荷电状态有密切关系。可以利用这一规律，通过MC的结构信息来预测其色谱保留行为，进而为优化色谱条件提供理论指导。     

Electron-Impact Total Ionization Cross Sections of Molecular Ions

The Binary-Encounter-Bethe (BEB) model for electron-impact total ionization cross sections of neutral molecules has been modified for molecular positive ions. The total ionization cross sections for H2+, N2+, CD⁺, and CO⁺ from the modified BEB formula are compared to available experimental data. The theory is in good agreement with experimental data on H2+, N2+, and CD⁺, but the experimental data by Belic et al. on N2+, and CO⁺ are lower than the theory. The large difference between the theory and experiment on CO⁺ is a strong indication of the dominance of the dissociative ionization channel, CO⁺→C⁺+O⁺, which was not included in the experiment.     

元素电负性及其影响因素

本文介绍了八种电负性的标度方法及特点,并对电负性的影响因素进行了讨论。