Neural network and principal component regression in non-destructive soluble solids content assessment: a comparison

Visible and near infrared spectroscopy is a non-destructive, green, and rapid technology that can be utilized to estimate the components of interest without conditioning it, as compared with classical analytical methods. The objective of this paper is to compare the performance of artificial neural network (ANN) (a nonlinear model) and principal component regression (PCR) (a linear model) based on visible and shortwave near infrared (VIS-SWNIR) (400–1000 nm) spectra in the non-destructive soluble solids content measurement of an apple. First, we used multiplicative scattering correction to pre-process the spectral data. Second, PCR was applied to estimate the optimal number of input variables. Third, the input variables with an optimal amount were used as the inputs of both multiple linear regression and ANN models. The initial weights and the number of hidden neurons were adjusted to optimize the performance of ANN. Findings suggest that the predictive performance of ANN with two hidden neurons outperforms that of PCR.     

日本对虾β-actin基因的克隆表达与纯化

利用RT-PCR技术从日本对虾中克隆到β-actin基因的cDNA,通过双酶切将其克隆到原核表达载体pGEX-4T-2中,转化大肠杆菌E.coli BL21感受态细胞,获得阳性克隆.4℃下IPTG诱导表达,Glutathione Sepharose 4B纯化后获得高纯度的β-actin蛋白.①     

肠道菌群结构多样性初筛研究

目的：探讨研究肠道菌群结构的初筛方法,为进行有效、高质量的高通量测序奠定基础.方法：用粪便采样器采集健康儿童粪便进行粪便标本预处理后,采用酚—氯仿方法提取样本菌群基因组DNA,并进行16S rDNAV3区片段PCR扩增,扩增产物用变性梯度凝胶电泳法（denaturing gradient gel electrophoresis,DGGE）检测分析.结果：采用该方法成功地扩增出16S rDNA V3区230bp的片段,经DGGE的方法可以比较出不同儿童粪便样本菌群结构的不同.结论：基于16S rDNA V3区的PCR-DGGE技术能够应用于研究肠道微生物多样性,对于肠道微生物的研究起到了初筛的作用.     

对《鱼缸中的怪现象》一文的质疑

指出《鱼缸中的怪现象》一文的错误，给出厚透镜的焦点公式，找出了呈现放大虚像的关键，并探讨鱼在鱼缸中“消失”的原因。     

快速诊断小鹅瘟PCR方法的优化建立

为建立快速诊断小鹅瘟的PCR方法,根据已发表的GPV主要结构蛋白VP3基因序列,经多序列比对和Oligo6．0软件分析设计特异性PCR引物。以微量法提取病鹅肝组织DNA,优化PCR反应引物退火温度、循环次数和鉴定其特异性,并与酚氯仿法和煮沸法进行同步对比研究。结果显示,建立的PCR检测方法能够特异性检测病鹅肝组织中GPV的核酸,其扩增片段大小为343bp,最佳退火温度为58℃,最佳循环次数为35次。微量法提取的病毒核酸PCR检测灵敏度分别是酚氯仿法的50倍和煮沸法的2500倍。该PCR检测方法不与鹅副黏病毒、禽流感病毒、传染性支气管炎病毒、鸭瘟病毒以及健康鹅肝组织发生交叉反应。本研究建立的GPVPCR检测方法能够快速诊断小鹅瘟。     

一类非线性时滞积分不等式中未知函数的估计

通过对一类具有弱奇异核的非线性时滞积分不等式进行讨论,给出了这一类不等式中未知函数的估计,并且利用构造辅助函数的方法,运用换元、放大、求导、积分等分析技巧证明了主要的结果.     

论增词法在英汉翻译中的应用

增词法是一种非常普遍而且有效的翻译技巧,它通过增加一些词来更真实通顺地表达原文的思想内容,并且适应目标语读者的阅读习惯。英汉翻译中的增词翻译有三方面的内容：语法增词、修辞增词和逻辑增词。     

英汉翻译增词译法应用分析

增词译法是常用的翻译技巧之一。由于英汉语言、思维模式与叙述方式的差异,增词译法的效用主要在于弥补词义非完全对应、弥补句法差异、满足译文语用和弥补文化差异。在翻译中灵活运用增词译法才能使译文做到真正的"忠实"、"通顺"。     

禽肉在储存过程中菌群结构变化研究

研究禽肉储存过程中菌群的变化,为其长期贮存奠定理论基础.采用酚氯仿异戊醇法提取禽肉中菌群基因组DNA,并通过PCR扩增及DGGE电泳技术探讨其随保存时间延长,菌群结构变化情况.结果表明,成功扩增了菌群基因组DNA,为230bp.DGGE电泳结果发现,DGGE分子指纹图谱上条带存在显著的差异,用bionumberics软件分析DGGE结果,发现第一天和第二天样本的相似度最高为0.75,第三天与第一天相比,相似度为0.47,第四天与第三天相比,相似度又下降为0.16,表明禽肉在储存过程中不断有新的菌种出现,但是具体是什么菌种有待于高通量测序分析.     

Cytokine Gene Polymorphism in Idiopathic Nephrotic Syndrome Children

The pathogenesis of idiopathic nephrotic syndrome is not completely understood. We postulate that cytokine gene polymorphisms may influence susceptibility or clinical course in Idiopathic Nephrotic Syndrome. Polymorphisms of IL-4, IL-6, and TNF-α cytokines were investigated in 150 children with Idiopathic Nephrotic Syndrome and 569 healthy controls by using polymerase chain reaction and restriction fragment length polymorphism. On comparing patient with controls strong association were found for IL-6, TNF-α and IL-4 at allelic level (IL-6-G174C (G vs. C): P = <0.001; OR = 6.33, TNF-α-G308A (G vs. A): P = <0.001; OR = 1.99, IL-4-C590T (C vs. T): P = 0.048; OR = 1.38). Further when SR group was compared with SS group significant association was found at genotypic level in all the studied genetic polymorphisms. Studied cytokine gene polymorphisms may influence susceptibility to idiopathic nephrotic syndrome and might affect steroid response in INS patients.