粮油食品防霉微生物筛选及其活性物质初步研究

为开发新型防霉剂,降低粮油食品储藏、运输、流通等过程中霉变对其品质和食用安全的影响,研究筛选获得具有强防霉活性的微生物。采用抑菌圈法,以禾谷镰刀菌（Fusarium graminearum）为指示菌筛选具有防霉活性的菌株。利用形态学观察、生化特征鉴定和16S rDNA基因序列比对进行菌株鉴定;通过不同温度、pH和蛋白酶K处理对防霉活性物质进行初步分析。结果显示：通过初筛获得33株对禾谷镰刀菌具有强抑制活性的菌株,复筛后选择的7株菌归属为芽孢杆菌属（Bacillus）;活性物质分析发现7株菌的活性物质均不耐高温和强酸碱,同时蛋白酶K处理对其防霉效果没有明显影响,初步推断为肽类;通过抑菌谱测定发现菌株ASAG 62对常见霉菌（产黄青霉Penicillium flavum、黑曲霉Aspergillus Niger、赭曲霉Aspergillus ochre、黄曲霉Aspergillus flavus、禾谷镰刀菌F. graminearum）均具有良好的抑制效果。     

超高效液相色谱-串联质谱法测定果蔬汁类及其饮料中22种镰刀菌属毒素

目的 建立果蔬汁类及其饮料中22种镰刀菌属毒素的超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry, UPLC-MS/MS)检测的实验方法。方法 样品经水和乙腈提取,QuEChERS净化,氮吹至近干,1 mL 80%乙腈水(体积分数)复溶,以乙腈和0.1%甲酸水(2mmol/L甲酸铵)为流动相,经ACQUITY UPLC CSH Phenyl-Hexyl 反相柱梯度分离,UPLC-MS/MS在正、负离子模式下多反应监测,基质配制外标法定量。结果 22种镰刀菌属毒素在线性范围内,相关系数平方(R2)均大于0.985,回收率在66.6%-119.1%之间,相对标准偏差在2.64%-14.96%之间。结论 该方法具有前处理方式简单、分析时间短、灵敏度好、准确度高、杂质干扰小等特点,可以用于果蔬汁类及其饮料中22种镰刀菌属毒素的检测。     

GaAlAs红外发光二极管功率老化对其1/f噪声特性的影响

在可靠性筛选中检测具有潜在损伤的器件一直是个难题.对GaA lAs红外发光二极管(IRLED)功率老化前后低频噪声的测量发现,1/f噪声幅值与偏置电流的γ次方成正比(小电流区γ=1,在大电流区γ≈2),且老化后1/f噪声幅值比老化前增大2个数量级.基于载流子数涨落和迁移率涨落机制建立了一个GaA lAs IR LED的1/f噪声模型,分析结果表明GaA lAs IR LED的1/f噪声在小电流时反映体陷阱特征,大电流时反映激活区陷阱特征,1/f噪声的增加归因于功率老化诱生的界面陷阱和表面陷阱,1/f噪声可以用来检测GaA lAs IR LED s的潜在缺陷.     

邻域搜索的粒子群优化算法及其性能分析

粒子群优化算法（PSO）是一种进化计算技术,是一种基于迭代的优化工具。但是,该算法的本身特性决定了算法不趋向于搜索接近极值点的解空间,造成了PSO算法最终解的局部极值性不好;并且,PSO算法需要充分的迭代才能够得到比较好的解,在迭代步数受到限制或者随时可能中途停机的情况下往往不能够得到比较好的解。根据PSO的这些不足,提出了邻域搜索的f-PSO算法,该算法在PSO的迭代步骤中每次更新全局最优解的同时采用一步局部寻优过程。实验表明,该算法具有很强的理论价值,在运算能力不足 、迭代不充分或中途停机的情况下,该算法仍然能够得到比较好的解。     

Fusarium graminearum Infection Strategy in Wheat Involves a Highly Conserved Genetic Program That Controls the Expression of a Core Effectome

Fusarium graminearum, the main causal agent of Fusarium Head Blight (FHB), is one of the most damaging pathogens in wheat. Because of the complex organization of wheat resistance to FHB, this pathosystem represents a relevant model to elucidate the molecular mechanisms underlying plant susceptibility and to identify their main drivers, the pathogen’s effectors. Although the F. graminearum catalog of effectors has been well characterized at the genome scale, in planta studies are needed to confirm their effective accumulation in host tissues and to identify their role during the infection process. Taking advantage of the genetic variability from both species, a RNAseq-based profiling of gene expression was performed during an infection time course using an aggressive F. graminearum strain facing five wheat cultivars of contrasting susceptibility as well as using three strains of contrasting aggressiveness infecting a single susceptible host. Genes coding for secreted proteins and exhibiting significant expression changes along infection progress were selected to identify the effector gene candidates. During its interaction with the five wheat cultivars, 476 effector genes were expressed by the aggressive strain, among which 91% were found in all the infected hosts. Considering three different strains infecting a single susceptible host, 761 effector genes were identified, among which 90% were systematically expressed in the three strains. We revealed a robust F. graminearum core effectome of 357 genes expressed in all the hosts and by all the strains that exhibited conserved expression patterns over time. Several wheat compartments were predicted to be targeted by these putative effectors including apoplast, nucleus, chloroplast and mitochondria. Taken together, our results shed light on a highly conserved parasite strategy. They led to the identification of reliable key fungal genes putatively involved in wheat susceptibility to F. graminearum, and provided valuable information about their putative targets.     

加压溶剂法提取雷公藤甲素及其条件优化

以雷公藤为原料,采用加压溶剂法提取雷公藤甲素,以1,2-二氯乙烷为溶剂,考察了提取时间、料液比和提取温度等因素对提取工艺的影响,并在单因素试验基础上,根据中心组合试验设计原理采用三因素三水平的响应面分析法进行工艺优化,得到提取过程优化的工艺条件为:料液比1:9.7,提取温度115℃,提取时间80min,雷公藤甲素的实际得率可达0.173‰,纯度为1.21%,与常规回流提取法相比优势明显。     

氧化剂对无铬木质素磺酸盐类钻井液处理剂作用效能的影响

为了提高无铬木质素磺酸盐在钻井液中的作用效能，用生产橡碗 栲胶的废渣为原料制备的无铬木质素磺酸盐，与氧化剂（Ｈ_２Ｏ_２、ＭｎＯ_２、 ＫＭｎＯ_４、ＨＮＯ_３、ＣａＣｌ_２Ｏ_７）进行反应，并测定氧化产物在钻井液中的作用 效能．结果表明，用 ＫＭｎＯ_4、ＨＮＯ_3和 ＣａＣl_2Ｏ_7作氧化剂时，其氧化产物 所处理的钻井液性能恶化；用Ｈ_2Ｏ_２和 ＭｎＯ_２作氧化剂时，其氧化产物所 处理的钻井液性能变好。     

1/f噪声的精确测量及其在太阳能电池可靠性筛选中的应用

为了实现对太阳能电池可靠性的筛选分类,建立了一套低频噪声自动测试系统.首先,根据太阳能电池1/f噪声的来源,确定了在大电流密度情况下以1/f噪声功率谱作为太阳能电池可靠性指示的可行性.然后,由测试得到的功率谱曲线明确了通过比较在f为1 Hz频点处的1/f噪声功率谱值大小可以区分太阳能电池的可靠性.最后,根据半导体器件可靠性试验验证的分类标准,给出了确定筛选阈值的方法.实验结果表明:该方法可以在短时间内无损地完成一批太阳能电池3个等级的可靠性分类,平均每个太阳能电池的测试时间只需5 min.采用该筛选方法,能精确检测单一器件,解决了传统方法花费大、周期长,易引起器件的损伤,且只能得到一批器件可靠性的统计规律的问题.该方法适用于对太阳能电池可靠性要求高的应用场合.     

几种杀菌剂对香蕉枯萎病菌的室内毒力测定

香蕉枯萎病是世界香蕉产区的重要病害之一，为了更有效的防治此病，我们选用11种药剂对香蕉枯萎病菌进行室内毒力测定，结果表明：18％保冶达乳油抑菌效果最好，EC50为0.13mg／L；15％三唑酮可湿性粉剂的抑菌效果最差，EC50为201．40mg/L。