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.     

2,2′-联咪唑硝基衍生物的合成及与DNA相互作用的研究

基于硝基咪唑类化合物有着广泛的抗微生物活性,合成了2,2′-联咪唑的单硝基NO2Hbiim和二硝基(NO2)2biim两种衍生物,通过元素分析、紫外光谱、红外光谱、热重分析对其进行了表征,并采用紫外光谱法、荧光光谱法和粘度法研究了二者与小牛胸腺DNA(ct-DNA)的相互作用。结果表明,化合物结构的共平面性对其与DNA的插入作用有较大的影响。     

逐步增加Ⅱ型截尾试验下广义指数分布的参数估计

基于逐步增加II型截尾试验,在单参数情况下,利用极大似然估计方法给出了广义指数分布形状参数和可靠度函数的极大似然估计.同时,在逐步增加II型截尾试验下,证明了极大似然估计的相合性和渐近正态性.     

阿司匹林载药淀粉微球吸附热力学和释药动力学的研究

以可溶性淀粉为原料,研究了淀粉微球在反相悬浮体系中不同温度下对阿司匹林的吸附行为,并考察其体外释放情况.结果表明：在实验条件范围内淀粉微球对阿司匹林的吸附量随着阿司匹林浓度的增加而增加.浓度相同时,温度越低,淀粉微球的吸附量也越大.吸附行为更符合Langmuir吸附模型,吸附为自发不可逆过程.总熵变是负值,焓变是主要的吸附驱动力.体外释放结果表明,阿司匹林淀粉微球聚合物在酸性介质中的释放行为更符合Higuchi方程,阿司匹林载药淀粉微球具有缓释作用.     

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.     

调血脂药物阿伐他汀的合成路线

阿伐他汀是一个高效、安全的调血脂药物,具有广阔的市场前景.作者综述了其经典的合成方法有Paal-Knorr法、不对称还原羰基法、消旋体苯乙胺拆分法、选择性醇醛缩合法等方法.为阿伐他汀的工业化发展和创新打下基础.     

替米考星β-CDP载药微球的制备及释药性能研究

采用共沉淀法制备了替米考星β-CDP载药微球,讨论了投药比、反应时间、反应温度对替米考星β-CDP载药微球的影响,并探讨了其体外释药情况,运用红外光谱仪、电镜、粒度分析仪对产物进行了表征。结果表明,在β-CDP微球质量为3g、替米考星质量为0．25g、反应温度为50℃、反应时间为1．0h、搅拌速度为400r·min^-1的条件下制得的载药微球的产率为81．60％、包封率为66．05％。替米考星β-CDP载药微球粒径分布均匀,外观圆整,在pH值为7．4的PBS中释药效果较好。载药微球释药与Korsmeyer—Peppas方程有较好拟合。     

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。