Changes in the content and antioxidative activity of β-carotene and its metabolite vitamin A during gastrointestinal digestion and absorption and optimisation of HPLC-based detection

The β-Carotene (BC), an important precursor of vitamin A (VA), possesses antioxidant activity but is fat-soluble and has low bioavailability. In previous in-vitro assays evaluating antioxidant and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) free radical scavenging, both BC and VA showed a strong ability to scavenge radicals and protected cells from oxidative stress. Here, we used artificially simulated gastrointestinal digestion and Caco-2 cell absorption models to evaluate the bioavailability of the BC during gastrointestinal digestion and absorption using high-performance liquid chromatography (HPLC) analysis. We observed high absorptive and transfer rates of BC and detected retinol metabolites (Vitamin A). Therefore, BC can be detected in the acidic gastrointestinal environment using HPLC. Optimised method provided better separation of BC and VA in the column, improving the accuracy of the test results.     

回转窑动态检测及托轮磨削的应用

我公司3#回转窑Φ4.8 m×74 m，三档支撑，带液压挡轮，斜度4％，设计产量5?000~6?000 t/d。回转窑运行过程中，筒体存在晃动现象，在窑尾密封处观察较为明显，晃动幅度约±20 mm，甚至导致三档托轮基础及周围栏杆也随之晃动。     

Metal-polyphenol-network coated CaCO3 as pH-responsive nanocarriers to enable effective intratumoral penetration and reversal of multidrug resistance for augmented cancer treatments

Construction of multifunctional stimuli-responsive nanotherapeutics enabling improved intratumoral penetration of therapeutics and reversal of multiple-drug resistance (MDR) is potent to achieve effective cancer treatment. Herein, we report a general method to synthesize pH-dissociable calcium carbonate (CaCO₃) hollow nanoparticles with amorphous CaCO₃ as the template, gallic acid (GA) as the organic ligand, and ferrous ions as the metallic center via a one-pot coordination reaction. The obtained GA–Fe@CaCO₃ exhibits high loading efficiencies to both oxidized cisplatin prodrug and doxorubicin, yielding drug loaded GA–Fe@CaCO₃ nanotherapeutics featured in pH-responsive size shrinkage, drug release, and Fenton catalytic activity. Compared to nonresponsive GA–Fe@silica nanoparticles prepared with silica nanoparticles as the template, such GA–Fe@CaCO₃ confers significantly improved intratumoral penetration capacity. Moreover, both types of drug-loaded GA–Fe@CaCO₃ nanotherapeutics exhibit synergistic therapeutic efficacies to corresponding MDR cancer cells because of the GA–Fe mediated intracellular oxidative stress amplification that could reduce the efflux of engulfed drugs by impairing the mitochondrial-mediated production of adenosine triphosphate (ATP). As a result, it is found that the doxorubicin loaded GA–Fe@CaCO₃ exhibits superior therapeutic effect towards doxorubicin-resistant 4T1 breast tumors via combined chemodynamic and chemo-therapies. This work highlights the preparation of pH-dissociable CaCO₃-based nanotherapeutics to enable effective tumor penetration for enhanced treatment of drug-resistant tumors.

     

A unified critical state model for geomaterials with an application to tunnelling

This paper is prepared in honour of Professor E.T. Brown for his outstanding contributions to rock mechanics and geotechnical engineering and also for his personal influence on the first author's research career in geomechanics and geotechnical engineering. As a result, we have picked a topic that reflects two key research areas in which Professor E.T. Brown has made seminal contributions over a long and distinguished career. These two areas are concerned with the application of the critical state concept to modelling geomaterials and the analysis of underground excavation or tunnelling in geomaterials.Partially due to Professor Brown's influence, the first author has also been conducting research in these two areas over many years. In particular, this paper aims to describe briefly the development of a unified critical state model for geomaterials together with an application to cavity contraction problems and tunnelling in soils.     

典型化工生产单元操作一体化实训室数字化课程学习系统建设

基于对典型化工生产单元操作一体化实训室数字化课程学习系统建设实践，将复杂且具有高度危险性的化工生产单元操作过程教学、培训等，构建成一个高度信息化的综合平台，利用视频、动画、微课、仿真等软硬件组成数字化的学习系统，即解决了学校资源、资金、场地、安全等的不足，方便学生随时随地学习，又解决了教师枯燥难教的困境，同时也解决了校内学资源碎片化、校际缺少共享等问题，为教学、培训、社会服务等提供便捷途径。     

A miniature triaxial apparatus for investigating the micromechanics of granular soils with in situ X-ray micro-tomography scanning

The development of a miniature triaxial apparatus is presented. In conjunction with an X-ray micro-tomography (termed as X-ray μCT hereafter) facility and advanced image processing techniques, this apparatus can be used for in situ investigation of the micro-scale mechanical behavior of granular soils under shear. The apparatus allows for triaxial testing of a miniature dry sample with a size of \mathrm{8}\hspace{0.17em}\mathrm{mm}\times \mathrm{16}\hspace{0.17em}\mathrm{mm} (diameter \times height). In situ triaxial testing of a 0.4–0.8 mm Leighton Buzzard sand (LBS) under a constant confining pressure of 500 kPa is presented. The evolutions of local porosities (i.e., the porosities of regions associated with individual particles), particle kinematics (i.e., particle translation and particle rotation) of the sample during the shear are quantitatively studied using image processing and analysis techniques. Meanwhile, a novel method is presented to quantify the volumetric strain distribution of the sample based on the results of local porosities and particle tracking. It is found that the sample, with nearly homogenous initial local porosities, starts to exhibit obvious inhomogeneity of local porosities and localization of particle kinematics and volumetric strain around the peak of deviatoric stress. In the post-peak shear stage, large local porosities and volumetric dilation mainly occur in a localized band. The developed triaxial apparatus, in its combined use of X-ray μCT imaging techniques, is a powerful tool to investigate the micro-scale mechanical behavior of granular soils.     

三相交流电动机启动过程参数数值模拟

提出一种进行模拟计算电动机启动过程中各参数的新方法。利用电机运行理论,结合物体定轴转动定律,推导出电机运行参数随时间变化的函数关系式。将计算公式离散化后,对电机启动过程运行规律进行求解。实例计算了一种型号潜油三相电动机启动时电动机定子电流、转子电流、激磁电流、扭转力矩、转速参数及效率参数等随时间或转差率的变化规律,其变化曲线与试验结果基本一致,说明提出的计算方法是有效、正确、适用的。     

芳烃联合装置节能降耗方法探讨

结合芳烃联合装置的发展形势，通过对国内某4套典型芳烃联合装置运行能耗的构成进行分析，确定该类装置的主要能耗在于燃料、电和蒸汽的消耗。总结了目前国内外常用的芳烃联合装置节能降耗方法，利用实际经验和调研结果，从采用新型吸附剂、采用单台吸附塔新工艺、采用轻质解吸剂替代对二乙苯（PDEB）、优化吸附塔运行参数、加热炉节能优化和选用高效节能设备等角度探讨芳烃联合装置的节能降耗方法。芳烃联合装置节能降耗应该由设计单位和生产单位紧密结合，在设计阶段就应充分考虑生产过程面临的问题，充分优化工艺路线、方案和设备设计，尽可能降低装置的能耗。同样，装置运行过程中，生产部门应标准化、精细化管理，优化日常操作，从而进一步降低装置的操作能耗。     

载体对钯基选择加氢催化剂性能的影响

以常规浸渍法制备了一系列Pd基催化剂，考察载体结构、织构及组成对其加氢性能的影响。采用程序升温技术（TPR-H2、TPDCO）对催化剂进行了表征和相应分析。结果表明，Al2O3载体中以高温1100℃焙烧后形成的占晶型具有更高的乙烯选择性。Pd基催化剂的Al2O3载体预先修饰MgO或CeO2后，能获得良好的金属分散度和适宜的反应物的吸附及产物的脱附特性，使得在高氢／炔体积比下催化剂样品上乙烯收率也维持在80％左右。在非Al2O3型载体制备的催化剂中，与金属Pd存在强相互作用的TiO2载体制备的催化剂的催化性能优越，最优样的乙烯收率达到95％。催化剂表面的Pd^hHx物种和Pd—C结合能在很大程度上影响着H2吸附活化和乙烯脱附能力，这对选择加氢性能有至关重要的作用。