Development and validation of an accurate and rapid LC-ESI-MS/MS method for the simultaneous quantification of aflatoxin B1, B2, G1 and G2 in lotus seeds

An accurate and rapid LC-ESI-MS/MS analytical method was developed and validated for the simultaneous determination of aflatoxin B₁, B₂, G₁ and G₂ in lotus seeds. The samples were firstly extracted with methanol-water solution (80:20, v/v), and then cleaned up by immunoaffinity columns. The mass spectrometer was operated in the positive ionization electrospray (ESI+) mode using multiple reaction monitoring (MRM) for analysis of four aflatoxins. The transitions of m/z 313 → 285 (AFB₁, CE 33 eV), m/z 315 → 259 (AFB₂, CE 37 eV), m/z 329 → 243 (AFG₁, CE 37 eV) and m/z 331 → 257 (AFG₂, CE 37 eV) were used to quantify these four aflatoxins, respectively. The limits of detection (LODs) of aflatoxin B₁, B₂, G₁ and G₂ were 0.007, 0.005, 0.003 and 0.005 μg kg^?1 based on a signal-to-noise ratio of 3:1, respectively. The limits of quantification (LOQs) of aflatoxin B₁, B₂, G₁ and G₂ were 0.02, 0.015, 0.01 and 0.015 μg kg^?1 based on a signal-to-noise ratio of 10:1, respectively. Recoveries for samples of spiked lotus seeds were all above 66% with relative standard deviation all below 15% for all compounds. Nineteen out of twenty batches of lotus seeds collected from different drug stores or markets in China were found to be contaminated with aflatoxins at different levels ranging from 0.02 to 688.4 μg kg^?1.     

Paclitaxel-loaded nanoparticles of star-shaped cholic acid-core PLA-TPGS copolymer for breast cancer treatment

A system of novel nanoparticles of star-shaped cholic acid-core polylactide-d-α-tocopheryl polyethylene glycol 1000 succinate (CA-PLA-TPGS) block copolymer was developed for paclitaxel delivery for breast cancer treatment, which demonstrated superior in vitro and in vivo performance in comparison with paclitaxel-loaded poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles and linear PLA-TPGS nanoparticles. The paclitaxel- or couramin 6-loaded nanoparticles were fabricated by a modified nanoprecipitation method and then characterized in terms of size, surface charge, surface morphology, drug encapsulation efficiency, and in vitro drug release. The CA-PLA-TPGS nanoparticles were found to be spherical in shape with an average size of around 120 nm. The nanoparticles were found to be stable, showing no change in the particle size and surface charge during 90-day storage of the aqueous solution. The release profiles of the paclitaxel-loaded nanoparticles exhibited typically biphasic release patterns. The results also showed that the CA-PLA-TPGS nanoparticles have higher antitumor efficacy than the PLA-TPGS nanoparticles and PLGA nanoparticles in vitro and in vivo. In conclusion, such nanoparticles of star-shaped cholic acid-core PLA-TPGS block copolymer could be considered as a potentially promising and effective strategy for breast cancer treatment.     

A DYNAMIC,ADAPTIVE, LOCALLY CONSERVATIVE,AND NONCONFORMING SOLUTION STRATEGY FOR TRANSPORT PHENOMENA IN CHEMICAL ENGINEERING

A family of discontinuous Galerkin (DG) methods are formulated and applied to chemical engineering problems. They are the four primal discontinuous Galerkin schemes for space discretization: symmetric interior penalty Galerkin, Oden-Babu?ka-Baumann DG formulation, nonsymmetric interior penalty Galerkin, and incomplete interior penalty Galerkin. Numerical examples of DG to solve typical chemical engineering problems, including a diffusion-convection-reaction system in a catalytic particle, a problem of heat transfer in a fixed bed, and flow and contaminant transport simulations in porous media, are presented. This article highlights the substantial advantages of DG on adaptive mesh modification over traditional methods. In particular, we propose and investigate the dynamic mesh modification strategy for DG guided by mathematically sound a posteriori error estimators.     

煤层瓦斯初始自然解吸速率和衰减系数及其意义

利用勘探钻孔煤心煤样的煤层瓦斯（煤层气）含量测定数据可求得煤层瓦斯自解速率和自衰系数,二者能直接而客观的反映煤中气体逸散的基本特征,对生产矿井煤层瓦斯涌出方式判断及突出危险性评价很有实用价值,可作为瓦斯突出危险性评价新指标。本文介绍了自解速率和自衰系数的计算方法,列举了陕北侏罗纪弱粘煤、山西晋城石炭二叠纪无烟煤及其它地区部分煤层的计算结果,分析了瓦斯含量、煤体结构、煤层温度等因素对自解速率和自衰系数的影响。     

Fe-Al合金有序化过程中的内耗峰

利用内耗方法对B2 Fe-Al合金的有序化过程进行了研究,并分析了有序化过程与原子换位运动之间的关系.对于油冷Fe47Al53合金,在570℃左右观察到一个内耗峰;但是对于炉冷样品,该峰并不出现.这个内耗峰具有典型的相变峰特征,XRD和DSC显示,该峰的出现与样品的有序化过程有关,它产生于反位链原子通过最近邻的空位向自身亚晶格位置的跳动. 油冷Fe57Al43合金中类似的峰出现在540℃附近.     

3Cr13Mo-42CrMo高耐磨耐蚀爆炸焊接复合轧辊试验研究

通过爆炸焊接炸药配方优化、锥形布药技术以及爆炸应力退火工艺的试验研究,研制一种在冷热交变、重负荷工况条件下,冶金设备所需的3Cr13Mo-42CrMo高耐磨耐蚀爆炸焊接复合轧辊。爆炸复合轧辊界面和表面性能检测表明：同其它方法相比,爆炸焊接复合轧辊由于外辊是轧制态,其耐磨性能高,而且辊芯和外辊结合强度高,大大提高了轧辊的使用寿命。复合轧辊不仅性能优良、使用寿命高,而且制造成本大大降低。     

钢轨接头用结构胶粘剂的研制与应用

介绍了一种钢轨接头胶接用的结构胶粘剂的制备、性能以及应用情况。该胶可在温（１２０℃）,０．５h固化,具有优良的剪切强度和韧性以及良好的耐湿性、耐介质性能。该胶粘剂室温贮存期可达２a,适合铁路部门批量生产钢轨绝缘胶接接头。     

粉尘防爆电气设备在粮食加工中的应用

主要阐述了粉尘防爆电气产品在粮食加工业中的应用及选型原则。     

文23气田低伤害酸化工艺技术研究与应用

文23低渗气藏具有埋藏深、物性差等特点,通过常规酸化对文23气田储层伤害的分析,研制出了气井低伤害酸液,筛选出防水锁剂JIX-Ⅱ、酸化缓蚀剂HSJ-Ⅱ等低伤害酸化添加剂,酸体系表面张力≤23m·N／m,界面张力≤0．5m-N／m,腐蚀速度〈5g／m^2·h（90℃）。室内岩心流动实验表明酸液具有较高的储层渗透率改善效果及较低的储层岩心伤害率。低伤害酸液体系与新型撬装气举残酸反排工艺的应用使得储层残酸、井筒积液反排彻底,提高了气井酸化效果。经过在文23气田15口井次的现场应用,平均单井日增气4．5×10^3m^3,平均有效期132d。表明该气井低伤害酸化工艺技术对于文23气田低渗气藏酸化改造具有良好的增产效果和广阔的推广应用前景。     

轧钢厂中多普勒激光测量仪的应用

随着经济的高速发展,多普勒激光测量仪在轧钢厂逐渐应用。激光测速仪可安装在钢坯的上方、下方或两侧,其采用非接触传感器测量钢坯速度和长度,灵敏度高,解决了钢坯长度不准的问题。