Development of molecularly imprinted electrochemical sensor with titanium oxide and gold nanomaterials enhanced technique for determination of 4-nonylphenol

4-Nonylphenol (4-NP) was reported to affect the health of wildlife and humans through altering endocrine function. A novel electrochemical sensor for sensitive and fast determination of 4-NP was developed. Titanium oxide (TiO₂) nanoparticles and gold nanoparticles (AuNPs) were introduced for the enhancement of electron conduction and sensitivity. 4-NP-imprinted functionalized AuNPs composites with specific binding sites for 4-NP was modified on electrode. The resulting electrodes were characterized by cyclic voltammetry (CV). Rebinding experiments were carried out to determine the specific binding capacity and selective recognition. The linear range was over the range from 4.80 × 10⁻⁴ to 9.50 × 10⁻⁷ mol L⁻¹, with the detection limit of 3.20 × 10⁻⁷ mol L⁻¹ (S/N = 3). The sensor was successfully employed to detect 4-NP in real samples.     

平地机后车架纵梁改进设计

平地机后车架主要由两根纵梁和一根后横梁组成。后车架上安装发动机、传动机构和驾驶室,车架下方固定在后桥上。后车架承受机体质量、工作载荷和地面传给机体的冲击,所以在后车架的设计中既要保证它有足够的强度、刚度,又要在现有生产能力和生产条件允许的情况下保证外形美观。     

两相邻深基坑同步施工关键技术

上海外滩国际金融服务中心项目基坑工程被枫泾路分为南、北2个深基坑,属典型软土地区两相邻深基坑同步开挖工程。针对工程工期紧、周边环境复杂、两相邻基坑同步开挖安全风险大等一系列难点,通过前期对不同开挖工况的有限元分析,确定了相邻基坑不超过一皮土高差的同步开挖原则,确保了基坑安全,满足了周边环境保护要求,达到了业主对工期节点的要求,取得了良好的社会效益。     

The effect of lactose, NaCl and an aero/anaerobic environment on the tyrosine decarboxylase activity of Lactococcus lactis subsp. cremoris and Lactococcus lactis subsp. lactis

The aim of this work was to study, under model conditions, combined effects of the concentration of lactose (0-1% w/v), NaCl (0-2% w/v) and aero/anaerobiosis on the growth and tyramine production in 3 strains of Lactococcus lactis subsp. lactis and 2 strains of L. lactis subsp. cremoris. The levels of the factors tested were chosen with respect to the conditions which can occur during the real process of natural cheese production, including the culture temperature (10 ± 1 °C). In all strains tested, tyrosine decarboxylation was most influenced by NaCl concentration; the highest production of tyramine was obtained within the culture with the highest (2% w/v) salt concentration applied. Two of the strains L. lactis subsp. lactis produced tyramine only in broth with the highest NaCl concentration tested. In the remaining 3 strains of L. lactis, tyramine was detected under all conditions applied. The tested concentration of lactose and aero/anaerobiosis had a less significant effect on tyramine decarboxylation. However, it was also found that at the same concentrations of NaCl and lactose, a higher amount of tyramine was detected under anaerobic conditions. In all strains tested, tyramine decarboxylation started during the active growth phase of the cells.     

Effect of heat treatment on the intermetallic layer of cold sprayed aluminum coatings on magnesium alloy

Dense and thick pure aluminum coatings were deposited on AZ91D-T4 magnesium substrates using the cold spray process. Heat treatments of the as-sprayed samples were carried out at 400 °C using different holding times. The feedstock powder, substrate and coating microstructures were examined using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) as well as Vickers microhardness analysis. The results demonstrate that aluminum coatings having dense and uniform microstructure can be deposited successfully using a relatively large feedstock powder. It has been identified that the intermetallics Al₃Mg₂ (γ phase) and Mg₁₇Al₁₂ (β phase) were formed at the coating/substrate interface during heat treatment. The growth rate of these intermetallics follows the parabolic law and the γ phase has a higher growth rate than the β phase. The thickness of the Mg₁₇Al₁₂ and Al₃Mg₂ intermetallic layers has reached 83 μm and 149 μm, respectively. This result is almost 45% higher than what has been reported in the literature so far. This is attributed to the fact that T4 instead of as cast Mg alloy was used as substrate. In the T4 state, the Al concentration in the Mg matrix is higher, and thus intermetallic growth is faster as less enrichment is required to reach the critical level for intermetallic formation in the substrate. The AZ91D-T4 magnesium substrate contains single α phase with fine clusters/GP-zones which is considered beneficial for the intermetallic formation as well as the intimate contact between the coating/substrate interface and the deformed particles within the coating.     

催化装置低温余热利用分析

通过对某石化厂催化装置低温余热利用现状进行分析,提出了利用催化装置低温余热的3个有效方案。通过综合比选后得出：将催化装置顶循热作为2号气分装置脱丙烷塔的重沸器热源,替代原来脱丙炕塔重沸器的加热蒸汽,合理地利用了催化装置的一部分余热。剩余热量以热媒水方式供热,直接供给厂内原有热用户、新建溴化锂制冷站和厂内主要办公大楼的夏季空调使用。从而较大的减少了炼厂蒸汽的使用量,减少了全厂循环冷却水的使用,提高了炼厂能源的综舍利用率,提高了炼厂经济效益。     

LSA based multi-instance learning algorithm for image retrieval

Focusing on the problem of natural image retrieval, based on latent semantic analysis (LSA) and support vector machine (SVM), a novel multi-instance learning (MIL) algorithm is proposed, where a bag corresponds to an image and an instance corresponds to the low-level visual features of a segmented region. Firstly, in order to transform every bag into a single sample, a collection of “visual-word” is generated by k-means clustering method to construct a projection space, then a nonlinear mapping is defined using these “visual-word” to embed each bag as a point in the projection space, thereby obtaining every bag's projection feature. Secondly, the matrix consisted of all the projection features of training bags is regarded as a term-document matrix, and LSA method is used to obtain the latent semantic feature of each bag. As a result, the MIL problem is converted into a standard single instance learning (SIL) problem that can be solved directly by SVM method. Experimental results on the COREL data sets show that the proposed method, named LSASVM-MIL, is robust, and its performance is superior to other key existing MIL algorithms.