乙醇及热处理对鲜切荸荠褐变的影响

以延缓鲜切荸荠在贮藏过程中的褐变并延长其货架期为 目的,研究了贮藏温度为4℃时,乙醇浸泡及热处理对鲜切荸荠色差、褐变度、总酚含量、苯丙氨酸解氨酶、多酚氧化酶和过氧化物酶等指标的影响.结果表明,几种处理延缓鲜切荸荠褐变效果为:联合处理＞乙醇处理＞热处理.与对照组相比,乙醇处理中PAL和POD的活性较低,热处理及联合处理组...     

A new strategy for the preparation of porous zinc ferrite nanorods with subsequently light-driven photocatalytic activity

Porous zinc ferrite (ZnFe₂O₄) nanorods have been synthesized by the thermal decomposition of ZnFe₂(C₂O₄)₃ nanorods precursor, which was prepared by template-, surfactant-free solvothermal method. The morphology and structure of the obtained ZnFe₂(C₂O₄)₃ nanorods precursor and porous ZnFe₂O₄ nanorods were characterized by X-ray powder diffraction, transmission electron microscopy, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results indicated that the as-synthesized ZnFe₂O₄ retained the precursor morphology of 1D nanorods with diameters of 100–200 nm and lengths of several micrometers and plenty of nanoparticles were interconnected to each other to form porous nanorods. The as-prepared ZnFe₂O₄ nanorods as a kind of subsequently light-driven photocatalyst exhibited good photocatalytic decomposition activity for methylene blue (MB).     

Characterization of polyaniline doped with diphenyl phosphate

UV–Vis spectroscopy and conductivity of the polyaniline (PANI) doped with diphenyl phosphate (DPHP), in comparison with that of HCl-doped polyaniline, show that the decrease in polaron delocalization and structural order results from the steric hindrance imparted by the longer chain counter ion. PANI protonated with DPHP is soluble in common organic solvents such as toluene, chloroform, dimethyl sulfoxide, etc. The conductivity of PANI/DPHP pressed pellet (at 25°C, 1.66 S cm⁻¹) increases with temperature from −40°C (1.18 S cm⁻¹) to +140°C (3.07 S cm⁻¹) due to thermal activation, and decreases with temperature from 140 to 180°C (0.25 S cm⁻¹) due to thermal undoping accompanied by the loss of some polarons. The temperature dependence of spin density is consistent with those of conductivity. After the heating scan, the conductivity (0.52 S cm⁻¹) at room temperature reduces to nearly one-third of the original value.     

佛手山药多糖对2型糖尿病大鼠糖脂代谢及氧化应激的影响

目的:探讨佛手山药多糖对实验性2型糖尿病大鼠糖脂代谢及体内氧化应激的影响。方法:SD大鼠高脂饲料喂养,结合小剂量腹腔注射链脲佐菌素40 mg/kg建立糖尿病大鼠模型,成模大鼠随机分为模型组、阳性对照组(二甲双胍150 mg/(kg·d))和佛手山药多糖组(400 mg/(kg·d)),并设正常组。观察给药期间各组体质量及血糖变化,给药6周后摘眼球取血,检测甘油三酯(triacylglyceride,TG)、胆固醇(total cholesterol,TC)、低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL-C)、高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL-C)、丙二醛(malonaldehyde,MDA)、一氧化氮(NO)含量及超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)活力,并解剖称取新鲜肝脏,测定肝糖原含量。结果:与模型组比较,佛手山药多糖能有效缓解糖尿病大鼠的症状,能明显降低实验性2型糖尿病大鼠空腹血糖水平(P0.05),对TC和LDL-C含量有极显著的降低作用(P0.01),对TG含量有显著降低作用(P0.05),能显著增加SOD和CAT的活力,而对肝糖原,HDL-C、MDA、NO含量及GSH-Px的活力无显著影响。结论:佛手山药多糖对实验性2型糖尿病大鼠有降低血糖作用,对血脂代谢紊乱有一定的调节作用,其降糖和降脂的具体机制可能与提高机体SOD、CAT活性相关。     

溶血性链球菌LAMP检测方法的建立

目的：研究溶血性链球菌的环介导等温扩增(loop-mediated isothermal amplification,LAMP)检测方法,实现对溶血性链球菌的快速检测。方法：针对溶血性链球菌的scpA 基因设计4 条特异性LAMP 内外引物进行LAMP扩增;优化扩增反应条件;采用包括溶血性链球菌在内的6 种不同菌株进行LAMP 的特异性检测,并酶切鉴定;对溶血性链球菌菌液以无菌水进行10 倍系列梯度稀释后,进行LAMP 扩增检测其灵敏度;将菌掺入牛奶样本并进行LAMP 检测。结果：本法可快速灵敏地检测出溶血性链球菌,反应特异性高,检出限为16.7CFU/mL,而牛奶样本的检出限则达10CFU/mL。结论：LAMP 法可用于食品溶血性链球菌的快速检测。     

3种食用油对大鼠脏器、生化指标及脂质过氧化的影响

通过研究花生油、菜籽油、大豆油对大鼠体重、脏器系数比、生化指标及脂质过氧化的影响,探讨这3种食用油对机体可能存在的危害,从而为居民合理摄取食用油提供理论依据。实验采用SD大鼠,按体重随机分为7组:对照组、花生油小剂量组(2.25g/kg)、花生油大剂量组(11.25g/kg)、菜籽油小剂量组(2.25g/kg)、菜籽油大剂量组(11.25g/kg)、大豆油小剂量组(2.25g/kg)、大豆油大剂量组(11.25g/kg)。灌胃3个月后测定各组大鼠的体重、主要脏器系数比、生化指标及脂质过氧化指标,并取部分肝脏冰冻切片,苏木精-伊红(HE)染色镜检。实验结果表明,与对照组相比花生油、菜籽油、大豆油大剂量组及大豆油小剂量组大鼠体重增加明显,菜籽油大剂量组肝体比升高明显、脾体比显著降低,花生油小剂量组睾丸体比升高,各组心体比无显著差异。与对照组比生化指标检测显示:菜籽油大剂量组超氧化物歧化酶(SOD)显著升高、谷草转氨酶(AST)显著降低;花生油小剂量组、大豆油大剂量组甘油三酯(TG)显著下降;菜籽油、大豆油小剂量组高密度脂蛋白胆固醇(HDL-C)显著升高。肝脏HE染色结果显示各组均无明显差异。实验结果:过量摄取3种食用油对体重和脏器有所影响,但无明显的毒副作用。     

新生小鼠骨骼肌成肌细胞分离和分化方法研究

建立一个高效的分离和分化小鼠成肌细胞的方案,以便探讨MAML1在转基因小鼠中肌管的形成和肌肉发生中的作用。使用细胞分化方法鉴定MAML1在肌肉发生中的作用。使用Western blot检测肌肉发生的标志蛋白肌球蛋白Myosin的表达。研究发现,传代次数少于5次及卫星细胞对成肌细胞在体外形成正确的肌管非常重要。不传代直接进行诱导分化,能促使成肌细胞形成更多的肌管。在MAML1转基因小鼠中,MAML1通过促进形成更多、更粗壮而长的肌管,提高肌球蛋白的蛋白水平来促进肌肉发生。这些MAML1转基因的肌管能够持续存在超过5天,然后才会降解。     

Correlation of viscoelastic behavior with water state and ultrastructure in hot air-dried carrots

This study evaluated and correlated the viscoelastic behavior, water state and ultrastructure of hot air-dried carrots. The results revealed that with increasing time, hot air-drying increased loss tangent (Tan δ) and reduced storage (G′) and loss (G″) moduli, cell wall components including total pectin (Tp), hemicellulose (He), and cellulose (Ce), free water (reflected by relaxation time T₂₃ and relative area M₂₃) in vacuoles, and immobilized water (T₂₂ and M₂₂) in cytoplasm and extracellular space in carrots. Pearson's correlation analysis showed that G′ and G″ were positively correlated (p < 0.01) with T₂₂, T₂₃, M₂₃, Tp, He, and Ce in dried carrots, whereas Tan δ was negatively with these indicators (p < 0.01). Principal component regression analysis revealed that the contribution rate of principal factor 1 and 2 (F1 and F2) was 72.7 and 21.9%, respectively. The Tp, He, Ce, T₂₃, and M₂₃ (42.3, 42.7, 42.5, 43.8 and 44.2% of the explained variance, respectively) were well explained by F1. The G′, G″, and Tan δ could be predicted by the following regression equation, G′ = 0.696 × F1, G″ = 0.680 × F1, and Tan δ = 0.341 − 0.652 × F1. These relationships were consistent with the more pronounced changes (plasmolysis of cytoplasm, disruption of plasmalemma and tonoplast, and degradation of cell walls and middle lamella) in the ultrastructure of dried carrots.     

Electrospinning combined with hydrothermal synthesis and lithium storage properties of ZnFe2O4-graphene composite nanofibers

ZnFe₂O₄-graphene composite nanofibers were prepared through electrospinning technique, then with graphene oxide by the facile solvothermal method to get the final products for the first time. The obtained ZnFe₂O₄ nanofibers composed of numerous same size nanoparticles wrapped by graphene sheets to form a unique nanostructure. When the ZnFe₂O₄-graphene electrode was evaluated as anode for lithium-ion batteries, good rate capability and long-term cycling stability could be achieved. The ZnFe₂O₄-graphene electrode exhibited a first discharge capacity of 2166 mAh g⁻¹ cycling at 0.05 C, remained an average reversible capacity of 1000 mAh g⁻¹ after 50 cycles, and kept the high rate capacities of 899, 822, 760 and 711 mAh g⁻¹ at the current rates of 0.5, 1, 2 and 5 C, respectively. The excellent electrochemical performance could be ascribed to the following reasons: the large electrochemical active surface area provided by the composite nanofibers; the graphene sheets decreased the internal resistance of the lithium-ion batteries, which resulted from the electrical conductivity of the graphene sheets; the graphene sheets as conductive network could effectively restrain the agglomeration of ZnFe₂O₄ nanopaiticals.