Chemical Composition and Biological Activities of Essential Oils from the Leaves,Stems, and Roots of Kadsura coccinea

The chemical composition and biological activities of the essential oils from the leaves, stems, and roots of Kadsura coccinea (K. coccinea) were investigated. The essential oils were extracted by hydro distillation and analyzed by gas chromatography mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GC-FID). Antioxidant activities of the essential oils were examined with DPPH radical scavenging assay, ABTS cation radical scavenging assay, and ferric reducing antioxidant power assay. Antimicrobial activities were evaluated by determining minimum inhibitory concentrations (MIC) and minimum microbiocidal concentrations (MMC). Acetylcholinesterase and butyrylcholinesterase inhibitory activity of the essential oils were also tested. A total of 46, 44, and 47 components were identified in the leaf, stem, and root oils, representing 95.66%, 97.35%, and 92.72% of total composition, respectively. The major compounds of three essential oils were α-pinene (16.60–42.02%), β-pinene (10.03–18.82%), camphene (1.56–10.95%), borneol (0.50–7.71%), δ-cadinene (1.52–7.06%), and β-elemene (1.86–4.45%). The essential oils were found to have weak antioxidant activities and cholinesterase inhibition activities. The essential oils showed more inhibitory effects against Staphylococcus aureus (S. aureus) than those of other strains. The highest antimicrobial activity was observed in the root oil against S. aureus, with MIC of 0.78 mg/mL. Therefore, K. coccinea essential oils might be considered as a natural antibacterial agent against S. aureus with potential application in food and pharmaceutical industries.     

Preparation and characterisation of ammonium polyphosphate intercalated layered double hydroxides composite by joint method with or without sonochemical technique

In this article, composites of ammonium polyphosphate (APP) intercalated layered double hydroxides (LDH) were prepared using joint methods (JM) and joint methods combined with a sonochemical technique (JMST). The structures of the composites were characterised by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry and energy dispersive X-ray spectroscopy. Results indicated that both methods allowed the combination of LDH with APP to form APP/LDH composites via covalent bonds. APP intercalation into LDH layers or grafting onto LDH surfaces using JMST was favourable. The APP content of APP/LDH composites prepared by JMST was 1.5 times higher than that in products prepared only by JM. Furthermore, composites prepared by JMST were smaller in size.     

表面纳米化对316L不锈钢低周疲劳性能的影响

超声喷丸(USSP)处理工艺在316L不锈钢表面制备出了纳米表面晶层,对表面纳米化后和未表面纳米化的316L不锈钢试样进行对比拉拉低周疲劳试验,运用数理统计学的方法分析研究了表面纳米化处理对316L不锈钢的低周疲劳性能的影响,并就表面纳米化对疲劳性能的影响机理进行了初步分析探讨.研究结果表明,超声喷丸表面纳米化处理可以有效地提高316L不锈钢的低周疲劳寿命;超声喷丸处理在表面所形成的残余压应力、晶粒细化的纳米强化表层是疲劳寿命提高的主要原因.     

凹叶厚朴各部位挥发油成分比较研究

采用顶空固相微萃取(HS-SPME)提取凹叶厚朴不同部位的挥发油成分,气相色谱-质谱(GC-MS)分析其组成.结果显示:根鉴定出19个化合物,其中4(14),11-桉叶二烯(26.04％),(1S-顺)-1,4-二甲基-7-(1-甲基亚乙基)-奠(24.94％),石竹烯(9.41％),β-桉叶醇(7.28％)为主要成分...     

非晶氧化锆水合物红外研究

用红外吸收光谱（ＩＲ）结合Ｘ射线衍射（ＸＲＤ）、差热（ＤＴＡ）和理分析（ＴＧ）详细研究了氧化锆前驱物（溶胶凝胶法制得的非晶态氧化锆水合物）的结构,实验结果表明在非晶态氧化锆水合物中有三种不同的近程结构,它表现为不同条件下制得的非晶氧化锆水合物的红外吸收谱在１７００～１２００ｃｍ＾－１水和羟基的弯曲振动吸收区出现１６３３、１５５１、１４００和１３４０ｃｍ＾－１四个不同的羟基吸收峰,这表明样品中有三种     

关于定积分微元法的一点补充

通过一个实例提出问题,进而给出微元法中推导微元及检验微元表达式的简便方法.     

原子吸收光谱法在烟草行业中的应用进展

对1961～2011年间3种类型的原子吸收光谱法,包括火焰原子吸收光谱法、石墨炉原子吸收光谱法和蒸气发生原子吸收光谱法在烟草行业中的应用进行了综述(引用文献63篇)。     

ICP-AES测定自制风味红枣豆浆的营养元素

通过正交试验设计实验方案,以方差分析优化实验条件制备得到了风味独特的红枣豆浆。采用ICP-AES测定自制红枣豆浆的Ca、Zn、Fe、Mn、Mg、Cu和K7种营养元素。该法简单、快速、灵敏度高,准确性好。回收率在96.9%—100.5%之间,相对标准偏差小于2.02%。实验结果表明:自制红枣豆浆中K、Ca、Mg、Fe、Zn含量较为丰富,风味独特、品质较好。     

多次测量随机误差分布的实验设计

利用Matlab设计多次测量时间的实验,首先使倒计时钟倒数,计算机自动取倒数到零的时刻t0,同时鼠标点击“计时”按键,程序取点击时刻t1,误差为t1-t0,多次测量后可以得到随机误差的分布,实验表明,误差符合高斯分布。