Evaluation of 10 pesticide residues in oranges and tangerines from Valencia (Spain)

One hundred and sixteen orange and tangerine samples from an agricultural cooperative of the Valencian Community (Spain) were analyzed for bitertanol, carbendazim, hexythiazox, imazalil, imidacloprid, methidathion, methiocarb, pyriproxyfen, thiabendazole, and trichlorfon by liquid chromatography–mass spectrometry (LC–MS) after a conventional multiresidue extraction procedure. Of 52 samples that contained pesticide residues, carbendazim was detected in 27 (51.9%) in the concentration range of 0.02–0.04 mg kg⁻¹, hexythiazox in 22 (42.3%) in the concentration range of 0.02–0.05 mg kg⁻¹, imazalil in 8 (15.0%) in the concentration range of 0.02–1.2 mg kg⁻¹, imidacloprid in 5 (9.6%) in a concentration range of 0.02–0.07 mg kg⁻¹ methidathion in 17 (32.6%) in the concentration range of 0.06–1.3 mg kg⁻¹, and methiocarb in 1 (2%) at a concentration of 0.02 mg kg⁻¹. Bitertanol, pyriproxyfen, thiabendazole and trichlorfon were not detected in any sample. Although 19 samples contained residues of two or three of the studied pesticides, no sample exceeded the European Maximum Residue Limits (MRLs). The results show that despite a high occurrence of pesticide residues in oranges and tangerines from Valencian Community, the contamination levels of these residues could not be considered a serious public health problem according to European Union (EU) regulations.     

Containerless processing of Ca-Sr-Si system bioactive materials: Thermophysical properties and ion release behaviors

Silicate materials have shown excellent bioactivity to enhance bone regeneration by releasing bioactive ions to stimulate osteogenesis and angiogenesis. However, one of the remaining challenges is how to control the ion release from biomaterials in order to elucidate the relationship between the ion concentration and bioactivity. In this study, we report, for the first time, the synthesis of Ca-Sr-Si biomaterials by containerless processing (CP) technique and sol-gel (SG) method, and a systematic study on ion release behaviors of the materials. The phase and chemical compositions of the materials and the dissolution condition on ion release behaviors of the biomaterials were investigated. The results showed that CP was an effective method to prepare Ca-Sr-Si glass materials. The heat treatment promoted the phase transition of the glasses, and the ion release behaviors of the biomaterials can be tailored by controlling the chemical composition, phase composition, pH value and preparation methods.     

Modeling effects of gas bubbles on the mechanical behaviors of Ag/Bi-2212 round wires using a double cantilever beam bridge model

Due to the larger current-carrying property, Bi₂Sr₂CaCu₂O_x (Bi2212) superconductors have a great potential application in high field magnet. Bi2212 superconducting material can be fabricated as an isotropic round wire. However, there is 30% void space in the wire, such as gas bubbles. The void space has a larger influence on the property of the wire. In this paper, we will study the effect of gas bubble on the fracture behavior. Based on the double cantilever beam model and critical state theory, the mechanical behavior of Bi2212 wire is studied for decreasing field. Two different damage mechanisms are discussed using the strain energy release rate and strain of bridge. The results show that the large gas bubble can increase the strain of bridge. The central filaments with gas bubble are easier to be damaged than the edge filaments with gas bubble.     

黄芪总黄酮对大鼠原代成骨细胞的影响及其机制研究

在大鼠颅骨原代成骨细胞中加入不同浓度的黄芪总黄酮(ATF),用MTT法检测细胞增殖,用碱性磷酸酶(ALP)活性、Ⅰ型胶原及骨钙素水平检测细胞分化,用茜素红染色法检测细胞矿化,用ELISA法和Western blot方法检测成骨细胞中骨形成蛋白(BMP-2)及核心结合因子(Runx-2)的表达。结果表明,ATF能剂量依赖性地促进大鼠原代成骨细胞的增殖、分化及矿化,同时上调成骨细胞中BMP-2和Runx-2蛋白的表达。提示ATF可能通过上调成骨细胞中BMP-2和Runx-2的表达来促进成骨细胞的成骨活性。     

Quantisation and data quality: Implications for system identification

In the pursuit of online, data-driven process control, there is a need to determine the quality of the data being processed before actually using it. One area that needs to be considered is data quantisation. Although in many applications it has been assumed that the impact of quantisation is to solely increase the variance of the signal, in certain cases this may not hold. This is especially the case when dealing with signals from poorly quantised sources, such as temperature sensors. In this case, the effect of quantisation cannot be solely considered by the impact of the increase in the variance. Therefore, this paper will examine the effects of small scale quantisation with the view of determining an appropriate metric for measuring the effect on data quality of quantisation. It will be shown that if the ratio of the unquantised signal variance and the distance between quantisation step sizes are below a given threshold, then the identification of the process parameters will be problematic. Detailed numerical simulations as well as an example drawn from a real system are presented to validate the proposed metrics and approach.     

Comparison of enzymatic de-esterification of strawberry and apple pectin at elevated pressure by fungal pectinmethylesterase

Water soluble pectin was isolated from strawberries. Sugar composition, degree of esterification and molar mass were compared with commercial apple pectin. Both pectins were subjected to enzymatic de-esterification by recombinant Aspergillus aculeatus pectinmethylesterase (PME). Rate of enzymatic de-esterification at elevated pressures (0.1–500 MPa) and temperatures (20–60 °C) was assayed by measuring the release of methanol as a function of time. Optimal activity was observed at 200–300 MPa combined with 45–55 °C. At all conditions investigated, both pectins were de-esterified at similar initial rates. However, after prolonged enzymatic treatment at atmospheric pressure and 30 °C, apple pectin was de-esterified to a significantly lower degree of esterification (7%) than strawberry pectin (32%). The mode of action of A. aculeatus PME was investigated by enzymatic fingerprinting of de-esterified pectin chains. The enzyme de-esterified according to a “multiple chain, multiple attack” mechanism, irrespective of the substrate.Industrial relevanceThis article demonstrates that both strawberry and apple pectin de-esterification by recombinant Aspergillus aculeatus PME is accelerated by high hydrostatic pressure. Since de-esterification of pectin in fruits gives rise to a texture improvement, this enzyme can be used to minimize texture damage during high-pressure processing of fruits and fruit-based products. It was also shown that this enzyme de-esterifies strawberry and apple pectin according to a “multiple chain, multiple attack” mechanism. The resulting pattern of esterification might have an influence on textural properties of fruits.     

新型核酸分子荧光探针——分子信标的研究进展

分子信标是基于荧光共振能量传递原理设计的一种发夹型寡聚核酸分子荧光探针,能够与待测核酸序列分子相互作用发生结构变化产生不同强度的荧光信号,具有高灵敏度、高选择性、适于活体检测等优点。对分子信标的结构、设计原理、热力学研究、选择性与动力学研究进行了综述,并对非典型分子信标（LNA-MB、SQ-MB）进行了介绍。     

仿生表面改性技术研究进展

从结构仿生和功能仿生两个方面对仿生表面改性技术进行了综述，对分子印迹技术、模拟生物酶催化、仿细胞膜结构改性、智能高分子凝胶及生物传感器进行了介绍，并对仿生表面改性技术的发展趋势进行了展望。     

卫星导航系统数据传输优化技术OPNET仿真

卫星导航系统由空间段、地面段和用户段3部分组成。地面段由主控站、监测站、注入站和与之互联的高性能通信网络组成,承担空间段导航的控制和星座管理,为用户安全可靠地使用整个系统提供保障服务,而高性能的互联通信网络则为地面段的数据传输提供了具有服务质量保证的平台。文中通过OPNET仿真软件,针对地面段中数据传输交换的通信质量管理问题,根据各站发送的各类信息重要性不同的特点,建立基于帧中继技术和基于帧中继甚小地球站卫星通信网络数据传输网络场景,对数据是否采取优先级传输进行仿真测试,通过数据分析,为高性能的卫星通信网络优化部署提供有意义的建议。