Determination of peptide antibiotic in milk by high performance liquid chromatography tandem mass spectrometry

Chuanbin Zhang, Hailan Huang, Fei Yuan, Feng Zhang, Zonghua Wang

Abstract: High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for the determination of bacitracin in milk. Acidified acetonitrile was used as the extraction solution and to remove the protein in sample. The sample was purified with PSA and C18. The chromatographic and mass spectrometric conditions were optimized, Electrospray ionization (ESI⁺), multiple reaction detection (MRM) mode and external standard method were used for quantification. The results show: The target compound have a good linear in the range of 50~1000 μg/kg. The correlation coefficient is greater than 0.999. The limit of detection (LOD) was 15μg/kg and the limit of quantification (LOQ) was 50μg/kg. The average recoveries were 89.4~101.2% at different spiked levels, and the relative standard deviations were 5.4~7.1%. The pretreatment method is simple and rapidly, the developed method has the advantages of high sensitivity, good accuracy and precision, and can meet the confirmation and quantitative analysis of polypeptide antibiotic residues in milk.

: Download (free)  CSE-PDF

Confidence intervals for process capability indices under unbalanced one-way random effect model

Wenjing Song, Xinmin Li

Abstract: The generalized confidence intervals for the process capability indices (PCIs) are given in the unbalanced one-way random effect model using fiducial inference. The simulation studies show that the performance of fiducial generalized inference is obviously close to the nominal confidence level. An industrial example is provided to illustrate the results.

: Download (free)  CSE-PDF

Finite element analysis of temperature field of reinforced concrete simply supported beam

Shan Zhao, Zhinian Yang, Jian Li

Abstract: Fire is one of the most common disasters. It could cause the collapse of fire architectural structure and harm people’s life and properties’s afety. Therefore, the fire resistant design of structures is especially crucial. As a result of the integrity of a building’s structure, components of a reinforced concrete frame structure have relatively great interaction between each other, and their mechanical properties and isolate members are quite different when they suffer from fire. At present, it is a lack of the research which takes both end constraint and fire resistance of restrained T-beams into account. At the same time, the fire resistance properties of high-level reinforced concrete frames are not discussed deeply.

: Download (free)  CSE-PDF

The research progress of Phosphatidylinositol 3-kinase (PI3K) inhibitors

Ruyi Jin, Tian Tang, Chuyue Zeng, Hanlin Feng, Lin Yu, Hongzong Si

Abstract: Phosphatidylinositol 3-kinases (PI3Ks), a family of serine/threonine lipid kinases, are a key signaling component of the PI3K/AKT signal transduction pathway that plays a important role in regulating cell growth, proliferation, motility, and survival. Since the dysregulation of this pathway has been frequently found in human cancers, in particular brain, breast, colon, NSCLC and gastric. Many PI3K inhibitors have been developed as preclinical and clinical drugs in globally pharmaceutical industry. This review contains the research progress of PI3K inhibitors in recent years.

: Download (free)  CSE-PDF

Studies on the IC₅₀ of Metabolically Stable Dibenzo[b、e]oxepin-11（6H）-ones as Highly Selective p38 MAP Kinase Inhibitors

Xiaoqian Liu, Yutao Zhao, Shanyu Xu, Dongdong Tian, Fucheng Song, Hongzong Si

Abstract: In this study, the QSAR (quantitative structure-activity relationship) model led to the discussion of a highly potent and selective ligand for the p38α MAP kinase inhibitors between the physical and chemical structure information of inhibition rate of cancer. All 62 ligands for the p38α MAP kinase inhibitors were divided randomly into training set with 48, and test set with 14. After molecular mechanics optimization with MM+ and AM1 by Hyperchem software, numerous descriptors were calculated by CODESSA software, including constitution, topolopy, geomrtry, electron, quantum chemistry descriptors. HM was used for the selection of optimal descriptor combination, which was as a group descriptors to build linear QSAR models by HM and GEP, respectively. As a significant result, HM has a precision of 0.82 and 0.76 in the training and test set, and the GEP accuracy of the training and test sets is 0.82 and 0.82. The results show that the both two quantitative constitutive relationship model has good prediction ability and two points, and further optimize the p38α MAP kinase inhibitor. The method is an effective application of carcinogenic compounds. The study can confirm some pivotal factors that influence the value of IC₅₀ and draw some new drugs. It will save lots of energy and resources.

: Download (free)  CSE-PDF