人参皂苷Rb1预适应对肥厚乳鼠心肌细胞缺氧复氧损伤的保护作用

目的: 研究人参皂苷Rb1 对心肌细胞缺氧复氧(H/R) 损伤的保护作用。方法: 用血管紧张素II(Ang II) 刺激乳鼠心肌细胞肥厚, 以0.01 ~ 10μmol·L^-1 Rb1 对H/R 损伤心肌细胞预适应给药48h, 检测心肌细胞表面积(CSA)、细胞蛋白含量(TP)、细胞凋亡率、细胞生存率和乳酸脱氢酶(LDH)、丙二醛(MDA) 及一氧化氮(NO) 含量。结果: 与H/R 组相比, Rb1 组CSA 和TP 分别减少41.56%和43.37%;细胞生存率增加2.28 倍;凋亡率降低85.29%;LDH、MDA 含量分别降低59.20% 和72.03%;NO活性增加2.67 倍(P <0.01)。结论: Rb1 显著减轻肥厚心肌细胞H/R 损伤, 机制与抑制细胞凋亡、减少脂质过氧化和LDH 释放、增强NO 活性有关。     

Thin porous nanosheets of NiFe layered-double hydroxides toward a highly efficient electrocatalyst for water oxidation

NiFe layered double hydroxides (NiFe-LDH) are low cost and earth abundant electrocatalysts for oxygen evolution reaction (OER). Herein, the NiFe-LDH nanosheets induced by ZIF-67 (NiFe-LDH/ZIF-67) were prepared via a coupling method of a self-sacrificing template method and a co-precipitation method. Atomic force microscope and field emission transmission electron microscopy analysis indicate that NiFe-LDH/ZIF-67 consist of thin porous nanosheets. X-ray photoelectron spectra analysis show that NiFe-LDH/ZIF-67 contains more oxygen vacancies than pristine NiFe-LDH. The overpotential of NiFe-LDH/ZIF-67 is 222 mV at 10 mA cm⁻² for OER, lower than that of ZIF-67, pristine NiFe-LDH, and the commercial RuO₂, indicating that its high electrocatalytic activity for OER. The high electrocatalytic activity of NiFe-LDH/ZIF-67 may be attributed to its thin porous nanosheet structure, which is derived from the structural influence of ZIF-67 and the coupling effect of a self-sacrificing template method and a co-precipitation method.     

Improved performance of Ni/Al2O3 catalyst deriving from the hydrotalcite precursor synthesized on Al2O3 support for dry reforming of methane

Exploiting Ni-based catalysts with excellent catalytic activity and anti-coking ability is significant for dry reforming of CH₄ with CO₂ (DRM) which is a promising route to CO₂ utilization. In this work, the Ni/Al₂O₃ catalyst with hydrotalcite precursor (NiAl-LDH) was synthesized by a facile in-situ growth method. And the effect of the NiAl-LDH structure on the catalytic activity and anti-coking ability of Ni/Al₂O₃ catalyst was revealed. The H₂-temperature programmed desorption (H₂-TPD) revealed that better Ni dispersion and more Ni–Al₂O₃ interface could be obtained by the NiAl-LDH precursor, which were vital for the activation of CH₄ and CO₂. Moreover, the NiAl-LDH precursor with non-LDH phase or turbostratic structure was also created by insufficient or extra amount of urea, and the obtained catalysts exhibited a poor catalytic stability, further confirming the importance of the LDH structure. In comparison with the Ni-IMP catalyst prepared by the conventional impregnation method, the CH₄ conversion increased by 16% and the carbon deposition decreased by 75% over Ni-6 catalyst with well-organized LDH precursor under the same reaction conditions. Hence, this work represents an important step toward developing Ni-based catalysts with excellent catalytic activity and anti-coking ability for DRM with the LDH precursor.     

Preparation and investigation of the combustion behavior of polypropylene/organomodified MgAl-LDH micro-nanocomposite

Layered double hydroxides (LDHs) are considered as a new emerging class of clays and they have a promising future in the field of nanocomposites due to their highly tunable properties. In this research, polypropylene/organomodified magnesium-aluminum LDH (PP/O-MgAl-LDH) composites were prepared by direct melt compounding. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the samples. Both XRD and TEM images of the composites illustrate the formation of a mixed morphology of micro and nano scale dispersion of MgAl-LDH in the matrix. Its combustion behaviors were examined via microscale combustion calorimeter (MCC), and char residues investigated by SEM. The MCC results show that the addition of Mg-Al-LDH into PP can efficiently decrease the specific heat release rate (HRR), the heat release capacity (HRC), and total heat release (THR), indicating the flame retardancy of the composite are improved. Flame retardant properties of PP/O-MgAl-LDH micro-nanocomposite were further enhanced with the increasing amounts of MgAl-LDH concentration.     

牛肉加热终点温度指示蛋白的筛选

研究旨在筛选出加热终点温度的指示蛋白，并建立指示蛋白与温度之间的关系，将牛肌肉汁加热到65℃，70℃，75℃和99℃，然后进行乳酸脱氢酶（LDH）和谷草转氨酶（GOT）活性测定。研究表明，乳酸脱氢酶随着温度的升高而降低。测量12个不同温度处理下肉汁中乳酸脱氢酶的活性，对温度和LDH酶活进行回归分析．结果表明在63．2～67．0℃温度范围内，温度与酶活呈线性关系，可用y=-0.0651x＋67.247表示，R^3为0.9755。因此乳酸脱氢酶可以用来监测肉类及肉制品的加热终点温度。     

EAA对HDPE/Al-Mg-LDH复合材料性能的影响

利用熔融共混法制备高密度聚乙烯(HDPE)/水滑石(LDH)复合材料,研究乙烯-丙烯酸共聚物(EAA)对复合材料的增容作用、力学性能以及结晶行为的影响.结果表明:EAA可以促进HDPE基体的结晶速率,提高复合材料结晶度;EAA对复合材料有很好的增容作用,能明显增强LDH与HDPE之间的界面粘合,促进LDH在基体中的有效分散;力学测试表明:加了EAA的复合材料比没有加EAA的复合材料力学性能有明显提高,且能使强度和韧性同时提高.     

Designing dual-functional nanohybrids for improving petroleum fractions through removing both phenyl-nonane and methyl-naphthalene

The present study focuses on using the adsorption character of the layered double hydroxide (LDH) for removal of aromatics species because of its simple production, suitable for ecology, cost less and easy to modify by intercalation organic molecules which cause change from hydrophilic to hydrophobic character and help in increase the removal percentage of mono- and di- aromatics. In this work, nanolayered structures (AlZn NLS) were prepared and characterized by different techniques but cannot remove aromatics. After intercalation by organic molecules (4-aminobenzoic acid, Salicylic acid, Adipic acid and n-capric acid in order), series of AlZn nanohybrids were prepared and showed significant removal of mono- and di-aromatics. The prepared nanohybrids based on n-capric acid showed significant results for removal of both mono-aromatics (33.5%) and di-aromatics (28.6%). The current study concluded that the nanolayered structures of AlZn became effective for removal aromatic species because of the expansion of the interlayered spacing of nanolayers and the increase of hydrophobic character.     

Nanocomposites of polymer gel electrolyte based on poly(ethylene glycol diacrylate) and Mg–Al layered double hydroxides

The present paper describes the synthesis and characterization of nanocomposite materials composed of the polymer gel electrolyte and a layered double hydroxide (LDH) inorganic filler. Mg–Al LDHs were prepared with various ratios of Mg/Al. It was observed that the layered structure of Mg–Al LDH was totally exfoliated by the PEGDA. The ionic conductivity and mechanical strength were highly improved in the nanocomposite systems. In the case of the composite films having 4.5 wt% of the Mg–Al LDH, the ionic conductivity reached 1.6 × 10^?3 S cm^?1 at room temperature. The incorporation of nanoparticles into the gel resulted in a two‐ or threefold increase in the tensile modulus. Copyright © 2004 Society of Chemical Industry     

低聚物插层水滑石及其与PP制备的纳米复合材料的性能研究

采用自由基溶液聚合的方法将苯乙烯(St)与对苯乙烯磺酸钠.(SSS)共聚,合成了低聚物P(St-co-SSS).然后通过共沉淀法分别制备了Mg-Al-LDH和低聚物P(St-co-SSS)插层的有机改性Mg-Al-LDH(OLDH).将LDH及OLDH分别与聚丙烯(PP)熔融共混,制备PP/LDH和PP/OLDH纳米复合材料.运用XRD、FT-IR、TGA、BET对LDH和OLDH的结构和性能进行了表征,并研究了其复合材料的热稳定性、阻燃性和力学性能.结果表明,合成的LDH具有典型的片层结构,而OLDH具有插层或剥离型结构;少量的OLDH的加入能够大幅度地提高复合材料的热稳定性,阻燃性和力学性能也明显提高.     

LDH型MoO_4~(2-)缓蚀剂的合成及防腐性能

采用共沉淀法制备了镁铝氢氧化物为层板、MoO24-柱撑的LDH型MoO24-缓蚀剂(记为MoO24-LDH),利用XRD和Raman光谱对样品进行表征。通过缓释实验,讨论了LDH型缓蚀剂的释放能力以及缓蚀剂的缓蚀机理。SEM-EDS、ICP、N2吸附脱附和极化曲线测试结果表明,合成的LDH型MoO24-缓蚀剂具有很好的离子交换和吸附Cl-的性能,释放出MoO24-缓蚀剂进入电解液,24 h内对镁合金的腐蚀电流保持在9.129μA/cm2,减缓了镁合金腐蚀。添加质量分数20%MoO24-LDH颜料的环氧涂层在质量分数3.5%NaCl溶液中的EIS测试体现出较好的耐蚀作用,耐盐雾腐蚀187 h以上。