Four phenolic acids from purple sweet potato and their effects on physicochemical,digestive and structural characteristics of starch

Liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) was employed to investigate free phenols that were released from purple sweet potato (PSP) by alkaline, acid and enzymatic hydrolysis. Four phenolic acids, including ferulic, isoferulic, 4-hydroxybenzoic and caffeic acids, were identified. Based on their effects on the characteristics of purple sweet potato starch (PSPS), the four phenolic acids were studied. Furthermore, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT–IR) and X-ray diffraction (XRD) techniques were employed to explore the microstructures of the complexes of the phenolic acids and PSPS. The obtained results demonstrated that the pasting, thermal, retrogradation, as well as digestive properties of PSPS were all influenced by the phenolic acids which interacted with PSPS through noncovalent hydrogen bonds. The influence of the four phenolic acids on the properties of PSPS was in the descending order: 4-hydroxybenzoic acid > ferulic acid > caffeic acid > isoferulic acid.     

Cryoprotection in electron microscopy

A set of experiments has been undertaken to resolve questions about the cryoprotection factor afforded by cooling specimens in the electron microscope. Two specimens, an n-alkane (paraffin) and bacterial purple membrane, were prepared and distributed to several laboratories. Radiation damage studies were carried out at these laboratories independently, but following a standard protocol as closely as possible. While it was not possible to make all measurements at all of the laboratories, sufficient data have been obtained to establish a general reproducibility in the overall features of the cryoprotection effect from room temperature to near 4.2 K.     

亚热带农业小流域暴雨过程硝态氮迁移特征及水文示踪研究

为揭示亚热带丘陵区农业小流域暴雨过程中硝态氮迁移规律及其主要水文输送途径,本研究通过对紫色土丘陵区典型农业小流域典型暴雨过程跨尺度(从3~1 236 hm2)连续监测,分析径流硝态氮迁移动态特征及其尺度效应,并对比δ18O和硝态氮作为示踪剂的端元混合分析(EMMA)解析结果,探讨硝态氮作为暴雨过程水文示踪剂的可行性。结果表明:(1)两场暴雨事件中源头小流域苏荣小流域(含集镇污水)径流中硝态氮浓度最高,而到达梯级小流域出口处(万安小流域)硝态氮浓度最低,林地来水的贡献是较大尺度小流域径流硝态氮浓度降低的主要原因,坡耕地壤中流补给可能是径流消退过程中硝态氮出现浓度峰值的主要原因。(2)EMMA模型解析结果显示:δ18O与硝态氮均能示踪农业小流域径流消退期间壤中流补给过程;但硝态氮在受人居活动强烈影响子流域的示踪应用需谨慎。以农业为主的亚热带丘陵区小流域中,硝态氮具有同时作为环境效应指示剂和水文示踪剂的潜力,但其应用效果仍有待于进一步验证。     

茶树芽叶花色苷含量测定方法的研究

茶树芽叶中的花色苷含量测定尚无国家标准,目前仍沿用单一pH法进行测定.比较了单一pH法和pH示差法对花色苷含量测定的结果.单一pH法所测花色苷含量高于pH示差法,两者存在良好的线性关系（R2=0.992 7）.pH示差法能较好地消除干扰物质对测定结果的影响,为茶叶的花色苷定量分析提供了依据.     

山药多糖提取工艺研究

对山药多糖提取工艺进行优化,得出较佳提取条件应用于山药多糖的提取。实验以山药多糖收率为指标,对山药预处理时间,提取过程中提取温度、提取时间、物水质量比及提取次数,重复性,回收溶剂再利用等因素进行了考察。结果表明：山药多糖的较优提取工艺为预处理时间（2＋2）h,提取时间2h,提取温度60℃,物水比1：20,提取次数1次;这样的提取工艺操作重复性好,溶剂回收再利用可行。     

The morphology and structure of crystals in Qing Dynasty purple‐gold glaze excavated from the Forbidden City

Ancient Chinese purple‐gold glaze (zijinyou) is popular for its beautiful figuration, unique allure and fine craftsmanship. To understand the crystalline nature in the purple‐gold glaze, the morphology and structure of crystals precipitated in the glaze layer of purple‐gold glaze porcelain fired during the Qing Dynasty were characterized by a variety of methods combining X‐ray and electron‐based techniques. A large quantity of single‐phase twinning ε‐Fe₂O₃ crystals with lengths of 1‐3 μm, widths of less than 1 μm, and thickness of approximately 150 nm are found dispersed across the glaze surface to a depth of approximately tens of micrometers. These crystals show stratification across the cross‐section of the purple glaze consisting of 4 sublayers according to the crystal size. The formation of ε‐Fe₂O₃ crystals primarily contributed to the reddish‐brown tones of the purple‐gold glaze. The presence of anorthite, a strong reducing atmosphere during the firing process and the vitreous nature of the glaze influenced the growth of ε‐Fe₂O₃ crystals. These results suggest the controllability of single‐phase ε‐Fe₂O₃ crystals by identifying and understanding the underlying chemical processes in ancient Chinese crystalline glaze porcelain, and the findings will provide insights for modern material scientists in preparing ε‐Fe₂O₃ crystals with large sizes and high purities.     

UV-C照射与壳聚糖涂膜保鲜处理对鲜切淮山营养品质的影响

对不同贮藏时间的鲜切淮山,采用3.0 kJ/m2剂量的短波紫外线(short-wave ultraviolet,UV-C)照射与质量浓度1.0%壳聚糖涂膜协同处理,研究两种保鲜方法对鲜切淮山营养品质的影响。研究发现,与对照组相比,在短波紫外线照射与壳聚糖涂膜保鲜处理过程中,鲜切淮山中的可溶性固形物、多糖、VC、淀粉、可溶性蛋白质均保持较高含量。研究表明,短波紫外照射与壳聚糖涂膜保鲜处理,有助于提升鲜切淮山的营养品质。     

山药复合营养面条加工工艺研究

以新鲜山药泥、小麦粉为主要原料,牛肉、胡萝卜、脱脂纯牛奶和食盐为辅料,制备一款营养丰富、无添加剂的新型山药复合营养面条。通过单因素试验、正交试验和感官评价,筛选山药复合营养面条配方;通过物性指标、微观结构确定山药复合营养面条的最佳配方为:山药泥35%、牛肉∶胡萝卜质量比为1∶1、脱脂纯牛奶3%和食盐2.5%。     

响应面法优化甘薯脆片干燥工艺

为探究甘薯脆片热泵干燥最佳工艺,在单因素试验基础上,以烘干温度、烘干时间、切片厚度、汽漂时间为影响因素,以含油率及感官评分为响应值,用Box-Behnken试验设计建立响应面分析模型。结果表明,甘薯脆片烘干最佳工艺为:烘干温度74℃、切片厚度2.7 mm、汽漂时间3 min,烘干时间为3.5 h,在此优化条件下,甘薯脆片油炸后感官评分为88.75分,含油率为7.84%,在此条件下得到的产品色香味俱全。     

一种新型毛羽检测装置的设计开发

设计了一种新型毛羽检测装置,对其结构组成进行了重新设计,主要包括传动箱与传动装置、收纱框、横动装置、检测盒、预张力加压装置,以及导纱组件与伸缩组件等。与现有的纱线毛羽检测装置相比,该装置结构简单合理,操作方便快捷,不会出现缠纱现象,可适用于不同大小的纱管进行毛羽检测,检测结果精确,并且能够在检测纱线毛羽的同时检测纱线的线密度,节约纱线,减少浪费。