A novel liquid chromatographic method with fluorescence detection for quantitation of tadalafil and dapoxetine hydrochloride in pharmaceutical dosage form and human plasma北大核心CSCD

Tadalafil( TAD)and dapoxetine HCl( DAP)are recently co-formulated and both show native fluo-rescence. Therefore,a novel,accurate,specific and sensitive reversed-phase high performance liquid chroma-tographic method with fluorescence detection was developed and validated for their separation and quantitation in dosage form and human plasma using avanafil as an internal standard( IS). Separation was achieved using isocratic elution within 7. 0 min on C18 column and acetonitrile-0. 15% triethylamine( 40∶60,v/v;pH 4)as a mobile phase. The flow rate was 1. 0 mL/min and the detection was time-programmed at 330,410 and 370 nm for TAD,DAP and IS,respectively,after excitation at 236 nm. The linear ranges from 0. 01 to 30. 00 μg/mL for each drug with the limits of detection of 4. 20 and 7. 20 ng/mL for TAD and DAP,respectively. The method was validated in accordance to the International Conference on Harmonization( ICH)guidelines and was successful-ly applied to spiked human plasma with mean recoveries of 98. 17% and 98. 83% for TAD and DAP respectively.     

Trihydroxybenzoic Acid Dimer-induced Apoptosis Effects in vitro

IntroductionTrapabispinosd roxbis a kind of traditional Chineseherbal medicine which is the fruit of water chestnutplant in the water chestnut family.It has functions ofclearing away summer-heat,allaying fever,dispersingdampness,dispelling pathogenic wind,nourishing qi,invigorating the spleen,relieving alcoholism,etc.[1].It contains various mineral elements and amino acidsand has a high edibility and importance as medicine.The research results in recent years show that it alsohas an anti-tumo…     

Nondestructive analysis of structural defects in wide bandgap II-VI heterostructures

X-ray scattering measurements of wide bandgap II-VI heterostructures show that stacking faults (which nucleate defects that are responsible for optical degradation of light emitting diodes and lasers) introduce significant levels of diffuse scattering near Bragg reflections of both the epitaxial layers and the GaAs substrate. We employed triple axis x-ray diffraction techniques to investigate stackingfault diffuse scattering and used cathodoluminescence and transmission electron microscopy to independently measure the stacking fault density. For comparison, double axis scans from the same samples were largely incapable of detecting the presence of these defects. Measurements taken at different azimuthal positions exhibit different levels of diffuse scattering and the diffuse scattering intensity is related to the stacking fault intensity in each <110> direction, which suggests that this technique can provide a non-destructive assessment of defects present in these systems. For some samples, the ZnSe buffer layer exhibited a tilt with respect to the substrate along a <110> direction; this tilt was greater than the tilt which would be attributed to growing a strained layer on the slightly miscut substrates which were used here.     

Bioinspired Design of a Robust Elastomer with Adaptive Recovery via Triazolinedione Click Chemistry

It is a significant but challenging task to simultaneously reinforce and functionalize diene rubbers. Inspired by “sacrificial bonds”, the authors engineer sacrificial hydrogen bonds formed by pendent urazole groups in crosslinked solution‐polymerized styrene butadiene rubber (SSBR) via triazolinedione click chemistry. This post‐crosslinking modification reveals the effects of the sacrificial bonds based on a consistent covalent network. The “cage effect” of the pre‐crosslinked network facilitates the heterogeneous distribution of urazole groups, leading to the formation of hydrogen‐bonded multiplets. These multiplets further aggregate into clusters with vicinal trapped polymer segments that form microphase separation from the SSBR matrix with a low content of urazole groups. The clusters based on hydrogen bonds, serving as sacrificial bonds, promote energy dissipation, significantly improving the mechanical properties of the modified SSBR, and enable an additional wide transition temperature region above room temperature, which endows the modified SSBR with promising triple‐shape memory behavior.

     

Covalent Fluorination Strategies for the Surface Modification of Polydienes

Nonreactive additives are widely applied to enhance polymer properties but can leach out of the material over time. In this work, two essentially different fluorinated additives bearing a triazolinedione moiety are synthesized and grafted on several polydiene backbones (acrylonitrile–butadiene–styrene, styrene–butadiene, and styrene–isoprene–styrene (SIS) copolymers), either by dip‐coating or by reaction in solution. The resulting polymers are analyzed by contact angle goniometry, size exclusion chromatography, and NMR, infrared, and X‐ray photoelectron spectroscopy. Independent of the modification procedure, the fluorophilic perfluoroalkyl additive is found at the material surface, thereby yielding a more hydrophobic surface. For SIS thermoplastic elastomers, for example, contact angles up to 125° can be obtained.

     

基于数据链的空战目标运动参数的转换

为了解决多机协同空战中数据链延时对空战态势判断带来的影响,本文应用了一种极坐标系下的卡尔曼滤波算法,对数据链的传输延时误差进行补偿,并在此基础上进行目标运动参数的转换,计算工程技术人员感兴趣但机载测量设备无法测量的目标信息,比如目标进入角。仿真结果表明,该算法对数据链延时的补偿误差较小,并能对数据链提供的目标数据进行比较精确的处理。     

Reversible TAD Chemistry as a Convenient Tool for the Design of (Re)processable PCL‐Based Shape‐Memory Materials

A chemically cross‐linked but remarkably (re)processable shape‐memory polymer (SMP) is designed by cross‐linking poly(ε‐caprolactone) (PCL) stars via the efficient triazolinedione click chemistry, based on the very fast and reversible Alder–ene reaction of 1,2,4‐triazoline‐3,5‐dione (TAD) with indole compounds. Typically, a six‐arm star‐shaped PCL functionalized by indole moieties at the chain ends is melt‐blended with a bisfunctional TAD, directly resulting in a cross‐linked PCL‐based SMP without the need of post‐curing treatment. As demonstrated by the stress relaxation measurement, the labile character of the TAD–indole adducts under stress allows for the solid‐state plasticity reprocessing of the permanent shape at will by compression molding of the raw cross‐linked material, while keeping excellent shape‐memory properties.