HPLC法测定麻杏止咳糖浆中苦杏仁苷的含量

建立高效液相色谱法测定麻杏止咳糖浆中苦杏仁苷含量的方法。采用KromasilC18柱,乙腈-0.1%磷酸溶液（8∶92）为流动相,流速1.0mL·min-1,检测波长207nm。苦杏仁苷在0.0406～0.812μg范围内有良好的线性关系, r=0.9999,平均回收率为99.0%,RSD为0.25%。本方法简便、准确、重现性好,可用于麻杏止咳糖浆的质量控制。     

Trapped polarons,free polarons and triplet excitons in π-conjugated polymer films and light-emitting diodes

Recent optically detected magnetic resonance studies of poly (p-phenylene vinylenes) (PPVs) and poly(3-alkyl thiophenes) (P3ATs) suggest that excitation at visible wavelengths λ_ex largely generates trapped polarons and polaron pairs, but UV excitation and carrier injection in LEDs generate free polarons. The photoluminescence (PL)-enhancing polaron resonance at long λ_ex is attributed to non-radiative recombination of trapped polaron pairs, which reduces their population and consequently the rate at which they non-radiatively quench singlet excitons. Interchain coupling, some defects induced by structural disorder, and sites adjacent to C₆₀^- counterions apparently enhance the generation of these trapped polarons as well as intersystem crossing from the singlet to the triplet manifold. At short λ_ex a PL-quenching polaron resonance emerges, and is assigned to fusion of photogenerated free polarons to bipolarons, which also quench singlet excitons. These interpretations imply that the l¹B_u exciton binding energy, defined as its dissociation energy to free polarons, is the difference between the absorption edge and the excitation energy at which the PL-quenching polaron resonance emerges. This difference is ∼0.8 eV in poly(2,5-dioctoxy-p-phenylene vinylene) and poly (3-hexylthiophene).     

超高效液相色谱法同时快速测定多种动物源食品中9种生物胺的含量

目的建立超高效液相色谱(ultra performance liquid chromatography,UPLC)同时测定动物源性食品中色胺、苯乙胺、腐胺、尸胺、组胺、章鱼胺、酪胺、亚精胺、精胺等9种生物胺的含量。方法样品经高氯酸溶液提取,丹磺酰氯柱前衍生化,加入氨水终止反应,乙腈定容。采用Acquity UPLC BEH C_(18)(2.1mm×100 mm,1.7μm)色谱柱,以5 mmol/L乙酸铵和乙腈作为流动相进行梯度洗脱,流速为0.4 mL/min,采用二极管阵列检测器在波长254 nm下检测。结果 9种生物胺在0.1~20μg/mL的范围内呈现良好的线性关系(r0.999)。样品在20、50和100 mg/kg 3个浓度水平的加标回收率为75.6%~97.2%,相对标准偏差为0.12%~5.32%(n=6);9种生物胺的方法定量限均为10 mg/kg。结论该方法简便、快捷、准确,可以用于动物源性食品中9种生物胺的同时测定。     

A parthenogenetic algorithm for single individual SNP haplotyping

The minimum error correction (MEC) model is one of the important computational models for single individual single nucleotide polymorphism (SNP) haplotyping. Due to the NP-hardness of the model, Qian et al. presented a particle swarm optimization (PSO) algorithm to solve it, and the particle code length is equal to the number of SNP fragments. However, there are hundreds and thousands of SNP fragments in practical applications. The PSO algorithm based on this kind of long particle code cannot obtain high reconstruction rate efficiently. In this paper, a practical heuristic algorithm PGA-MEC based on parthenogenetic algorithm (PGA) is presented to solve the model. A kind of short chromosome code and an effective recombination operator are designed for the algorithm. The reconstruction rate of PGA-MEC algorithm is higher than that of PSO algorithm and the running time of PGA-MEC algorithm is shorter than that of PSO algorithm, which are proved by a number of experiments.     

广西食品生产企业参与食品质量安全可追溯体系的主要影响因素研究

目的探究广西食品生产企业实施食品安全追溯体系的主要影响因素。方法采用理论假设及问卷调查,以广西区内101家食品生产企业为实例,主要从生产企业的内部影响因素、企业生产经营状况、企业对质量安全追溯体系的认知、企业对追溯体系建立过程中外部环境等4个方向进行调研,对问卷进行统计分析,建立Logistic模型。结果企业参与实施追溯体系的意愿较高,影响企业建设追溯体系的主要因素是企业是否获得质量认证、生产者对食品质量安全控制信息关注度、可追溯产品的预期价格、消费者是否可以追溯到质量问题主体。结论在广西目前的经济发展状况下,需要结合多方力量,运用阿里经营模式,多手段、多渠道地去推进食品安全追溯体系。     

2018年广西市售蔬菜镉污染现状及其暴露评估

目的 了解广西市售蔬菜中镉的污染状况, 评估广西居民通过食用市售蔬菜镉暴露风险程度。方法 利用2018年广西监督抽检蔬菜中镉含量数据和广西居民蔬菜平均摄入量数据, 采用点估计模型计算广西居民食用蔬菜中镉暴露水平。结果 9047批次蔬菜样品中, 镉平均含量为0.02322 mg/kg, 茎类蔬菜和豆类蔬菜镉检出率较低, 分别为56.52%和48.65%; 鳞茎类蔬菜镉超标率最高为6.90%; 批发市场蔬菜镉检出率和超标率最高, 分别为89.31%、5.66%; 全区14个地市市售蔬菜平均含镉量区别不大, I市镉检出率最高为97.16%, B市镉超标率最高, 为5.22%; 广西居民经食用市售蔬菜所致镉的月平均暴露量范围为1.77~5.29 μg/kg BW, 占每月可耐受摄入量(provisional tolerable monthly intake, PTMI)的7.08%~21.16%。结论 广西市售蔬菜中存在一定程度的镉超标情况, 但居民通过食用市售蔬菜的镉暴露量不高, 对人体的健康风险较小。