In vitro and in vivo antioxidative and hepatoprotective activity of aqueous extract of Cortex Dictamni

AIM To investigate the antioxidant and hepatoprotective effects of Cortex Dictamni aqueous extract(CDAE) in carbon tetrachloride(CCl4)-induced liver damage in rats.METHODS The in vitro antioxidant effect of CDAE was investigated using α,α-diphenyl-β-picrylhydrazyl(DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)(ABTS), β-carotene bleaching, reducing power, and thiobarbituric acid reactive substance assays. A linoleic acid system, including ferric thiocyanate(FTC) and thiobarbituric acid(TBA) assays, was used to evaluate the inhibition of lipid peroxidation. The in vivo hepatoprotective and antioxidant effects of CDAEagainst CCl4-induced liver damage were evaluated in Sprague-Dawley rats. Silymarin was used as a positive control. Liver damage was assessed by determining hepatic histopathology and liver marker enzymes in serum. Enzyme and non-enzyme antioxidant levels and lipid peroxide content were measured in the liver. Cytochrome P450 2E1(CYP2E1) protein expression was measured via immunohistochemical staining. Nuclear factor E2-related factor(Nrf2), heme oxygenase-1(HO-1), NAD(P)H quinine oxidoreductase 1(NQO1), and γ-glutamylcysteine synthetase catalytic subunit(γ-GCSc) protein expression was measured by Western blot.RESULTS Our results showed that CDAE exhibited a strong antioxidant activity in vitro. CDAE scavenged DPPH and ABTS radicals in a dose-dependent manner. CDAE inhibited lipid peroxidation with a lipid peroxide inhibition rate of 40.6% ± 5.2%. In the FTC and TBA assays, CDAE significantly inhibited lipid peroxidation(P < 0.01). In vivo histopathological studies indicated that CCl4-induced liver injury was alleviated following CDAE treatment in rats of both sexes. CDAE(160 and 320 mg/kg) significantly prevented CCl4-induced elevations of alkaline phosphatase, glutamate pyruvate transaminase, aspartate aminotransferase, and total bilirubin levels in rats of both sexes(P < 0.05, 0.01, or 0.001). Moreover, CDAE restored the decreased activities of hepatic antioxidant enzymes, including superoxide dismutase, catalase, and glutathione peroxidase, as well as non-enzyme antioxidant glutathione, which were induced by CCl4 treatment. CDAE significantly suppressed the up-regulation of CYP2E1 and promoted Nrf2, HO-1, NQO1, and γ-GCSc protein expression.CONCLUSION CDAE exhibits good antioxidant performance in vitro, with marked radical-scavenging and anti-lipid peroxidation activities. CDAE is effective in preventing CCl4-induced hepatic damage in rats of both sexes. The hepatoprotective activity of CDAE may be attributable to its antioxidant activity, which may involve Keap1-Nrf2-mediated antioxidant regulation.

不同脱色方法对三七多糖物理性质及体外抗氧化活性的影响

本文考察了活性炭脱色法和树脂脱色法对三七多糖(Panax notoginseng polysaccharide,PNP)的脱色效果、物理性质及其体外抗氧化活性的影响。以综合评分为评价指标,通过单因素实验考察活性炭用量、温度、时间,在单因素实验基础上采用正交实验优化脱色条件;通过静态吸附实验,从6种树脂中筛选最佳脱色树脂,随后通过单因素实验考察其上样量、脱色时间、转速对综合评分的影响,在单因素实验基础上采用正交实验优化脱色条件。通过溶解度、粒径、差示扫描量热分析、傅立叶变换红外光谱分析、pH值、相对分子质量及其大小分析比较未脱色的三七多糖(Unbleached Panax notoginseng polysaccharide,UPNP)、活性炭脱色法制备的PNP(Panax notoginseng polysaccharide prepared by activated carbon decolorization,PNPC)及D285树脂脱色法制备的PNP(Panax notoginseng polysaccharide prepared by D285 resin decolorization,PNPD)的物理性质;并比较三者对DPPH、ABTS^(+)自由基清除率、金属离子螯合能力。结果表明活性炭脱色的综合评分为78.00%;D285为最佳脱色树脂,综合评分为71.00%。与UPNP、PNPC相比较,PNPD溶解度低,在水溶液中粒径分布不均匀、稳定性较差,pH值增大、相对分子质量较大,体外抗氧化活性低。推测由于D285树脂离子交换过程中产生的强碱性环境,导致PNP糖苷键水解所致。不同脱色方法会对PNP物理性质、体外抗氧化活性产生影响。

不同溶解性面包果果胶的理化、结构性质及抗氧化活性的比较

该研究以面包果为原料,提取了水溶性果胶(Water-soluble Pectin,WSP)、螯合剂可溶性果胶(Chelate-soluble Pectin,CSP)、碳酸钠可溶性果胶(Sodium Carbonate-soluble Pectin,SSP),分析并比较了三者的理化性质、结构特性和抗氧化活性。结果表明:WSP具有高粘度(145.80 mPa·s)、高分子量(1241.3 ku)和高酯化度(86.33%)的特点,CSP具有低粘度(17.88 mPa·s)、低分子量(218.6 ku)和低酯化度(45.73%)的特点,SSP具有提取率高(47.73%)、溶解性好(96.20%)、粘度低(4.63 mPa·s)和分子量低(186.3 ku)的特点。三种果胶都主要由鼠李糖、阿拉伯糖、半乳糖、葡萄糖、木糖、半乳糖醛酸组成,红外分析光谱和扫描电镜结果表明这三种果胶的结构存在显著差异。抗氧化结果表明,WSP、CSP和+SSP对羟自由基、ABTS自由基和DPPH自由基的清除能力随质量浓度增加而增强。其中SSP对自由基的清除能力最强,在质量浓度为0.5 mg/mL时,对+ABTS自由基的清除率达到了96.56%。综上所述,SSP果胶表现出较好的抗氧化活性是由其较小分子量、支链丰富、低粘度以及光滑表面导致的。

Green hydrothermal synthesis of multifunctional carbon dots from cassava pulps for metal sensing,antioxidant,and mercury detoxification in plants

Carbon dots(CDs)have been attracted to nanocarbon materials for metal ion sensing,biological activity,and plant phytotoxicity due to their excellent photophysical properties,such as low cytotoxicity,high quantum yield,tunable fluorescence emission,and biocompatibility.Cassava pulp,which consists mainly of starch,has been identified as a low-cost biomass waste from the cassava starch industry.Therefore,this research developed CDs and nitrogen-doped CDs(NCDs)from cassava pulp using a one-step hydrothermal process in deionized water at 200℃.The effects of the synthesis conditions,including reaction time(6-24 h)and the nitrogen doping derivatives,were also investigated.CDs and ethylenediamine doped-NCDs exhibited tunable fluorescence emission,strong quantum yield,high photostability,and tolerance to photobleaching.Furthermore,the potential applications of CDs-12 h were demonstrated such as fluorescent sensors for metal ion sensing,antioxidant activity,and mercury detoxification in plants.Fluorescence quenching of the CDs-12 h via both static and dynamic quenching mechanisms was observed in the presence of several metal ions such as Hg^(2+),Cu^(2+),and Fe^(3+)with the detection limit in micromolar levels and further applied to real water samples with good recovery and acceptable relative standard derivation.The paper test strip coated with CDs-12 h could also detect these metal ions under UV light.CDs and NCDs-EDA also showed potential DPPH radical scavenging activity and alleviated mercury toxicity in the Chinese cabbage seedlings with the incubation of CDs-12 h and NCDs-EDA-12 h(30 mg/L).

Curcuma angustifolia ameliorates carbon tetrachloride-induced hepatotoxicity in HepG2 cells and Swiss albino rats

Objective:To determine the antioxidant and hepatoprotective potential of methanol extract of rhizome of Curcuma angustifolia(MECA)against carbon tetrachloride(CCl4)-induced hepatic damage in vitro and in vivo.Methods:DPPH,ABTS and reducing power assays were performed to estimate the antioxidant effect of MECA.In vitro cytotoxicity of MECA against HepG2 cells was evaluated,whereas serum biochemical parameters and levels of antioxidative enzymes were measured in vivo and in vitro.Additionally,histopathological studies were estimated in order to investigate the hepatoprotective efficacy of MECA.Furthermore,GC-MS analysis of the extract was performed to identify the chemical components.Results:MECA exhibited strong antioxidant activity and attenuated CCl4-induced decrease in the viability of HepG2 cells.Additionally,MECA significantly restored the ALT,AST,ALP,TP and albumin level in comparison with the CCl4 group.After pre-treatment with MECA,effects of SOD,CAT and GSH were increased as well as lipid peroxidation amount decreased on CCl4-induced hepatotoxicity in in vitro and in vivo model.Furthermore,histopathological observation confirmed that MECA reduced liver injury induced by CCl4 in rats.GC-MS analysis confirmed the presence of bioactive constituents such as α-tocopherol(12.27%),phytol(7.61%),squalene(3.71%),β-sitosterol(2.19%),eugenol(2.59%),curcumenol(1.20%),β-elemene(1.00%)and eucalyptol(0.89%).Conclusions:MECA contains antioxidant and hepatoprotective constituents such asα-tocopherol,phytol,squalene and eugenol and exerts hepatoprotective effect both in vitro and in vivo.

Comparative study on some selected species of <i>Ocimum</i>genus on free radical scavenging activity and hepatoprotective activity against CCl4 induced intoxication in rats

In this study, we compared the in vitro antioxidant property among the selected Ocimum species (O. sanctum, O. americanum, O. basilicum and O. gratissimum) and hepatoprotective activities of their extracts against CCl4 induced intoxication. The results suggested that the four species of Ocimum genus showed variability in Phenolic content and in vitro antioxi-dant activity against DPPH, superoxide and hydroxyl radicals in the following manner: O. sanctum > O. americanum > O. basilicum > O. gratissimum respec-tively. Based on serum AST, ALT, ALP and T. Bil levels, the alcoholic extracts of Ocimum species showed a significant dose dependent (250 mg and 500 mg and 750 mg/kg p.o.) and a protective effect against CCl4 induced hepatotoxicity in albino rats. The results further revealed that the potential hepatoprotective activity of Ocimum sanctum among the Ocimum species.

Phytochemical screening, hepatoprotective and antioxidant effects of leaf extracts of <i>Zapoteca portoricensis</i>

Fresh leaves of Zapoteca portoricensis are used in Eastern Nigeria for management/treatment of various disorders without any scientific basis. Hepatoprotective and antioxidant properties in albino rats, and phytochemical composition of distilled water and ethanol leaf extracts were studied. Fifty-five animals were placed in eleven groups (A-K) of five in each. Different doses (100, 200, 400 and 600 mg/kg body weight) of the extracts, 20 mg/kg body weight of vitamin C (standard antioxidant) and distilled water were orally administered to groups A-H, I and J-K respectively for six consecutive days. On the seventh day, 2.5 ml/kg body weight of carbon tetrachloride (CCl4) was given intraperitoneally to groups A-J, while group K received distilled. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma glutamyltransferase (GGT) were used to study hepatoprotective effect. Malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) levels in the liver were monitored to assess antioxidant activity. Phytochemical analysis revealed the presence of alkaloids, tannins, saponins, flavonoids, anthraquinones, terpenoids and cardiac glycosides in the extracts. Pretreatment of the rats with the extracts produced a significant decrease (p < 0.05) in ALT, AST, GGT and MDA, while the activity of SOD and CAT increased significantly (p < 0.05) relative to the positive control. These results, which were dose-dependent, are indicative of hepatoprotective and antioxidants potentials of the extracts, and may be due to their phytoconstituents.

不同提取工艺下海黄牡丹精油组分及其抗氧化活性的比较

【目的】分析不同提取工艺下海黄牡丹鲜花和烘干花瓣精油的化学成分及其体外抗氧化活性的差异,为海黄牡丹精油的综合利用与深度开发提供参考依据。【方法】采用同时蒸馏提取(SDE)法和超临界CO_(2)萃取(SFE)法分别提取海黄牡丹新鲜和烘干花瓣精油,利用气质联用技术(GC-MS)对精油成分进行分析,测定不同质量浓度精油对DPPH和ABTS自由基的清除率及其总抗氧化能力,并测定精油中生物活性成分总酚和总黄酮含量。【结果】采用SFE法提取的海黄牡丹精油得率明显高于SDE法,用SFE法从新鲜花瓣中提取精油得率最高,为0.76%。从2种不同方法提取的海黄牡丹鲜花和干花精油中检测到了108种化合物,其中SFE法提取的鲜花瓣精油中有41种、烘干花瓣精油中有52种,SDE法提取的鲜花瓣精油中有33种、烘干花瓣精油中有13种,植酮、正十九烷、正二十一烷3种主要成分在4种精油中同时存在。不同方式提取的海黄牡丹花精油中化合物成分主要有烷类、醇类、烯类、酮类、酯类、醛类、酸类、酚类和其他共9类化合物,其中烷类和醇类化合物的数量和含量显著高于其他类别化合物。不同方式提取的海黄牡丹精油对DPPH和ABTS自由基均具有一定的抗氧化清除活性,并且也具有一定的抗氧化能力,表现出SFE法提取的精油清除率高于SDE法,从新鲜花瓣中提取的精油清除率高于烘干花瓣。SFE法提取的新鲜花瓣精油中总酚含量最高,SDE法提取的烘干花瓣精油中总酚含量最低;总黄酮含量以SFE法提取的烘干花瓣精油中最高,SDE法提取的烘干花瓣精油中最低。【结论】不同方法提取的海黄牡丹鲜花和烘干花瓣精油的得率和化合物组成存在一定差异,SFE法提取的新鲜花瓣精油在体外的抗氧化活性优于其他提取方式。

响应面法优化活性炭对附子多糖的脱色工艺及抗氧化性研究

采用响应面分析法优化活性炭对附子多糖的脱色工艺,并测定了脱色后的附子多糖的抗氧化性。根据前期的单因素实验结果,以活性炭的用量、脱色的温度和脱色的时间为自变量,脱色率为响应值,利用Box-Benhnken中心组合实验并结合响应面分析法,优化附子多糖的脱色工艺,并通过测定DPPH自由基和羟基自由基的清除率,来评价脱色后的附子多糖的抗氧化性。结果表明,附子多糖的最佳脱色工艺条件为:活性炭用量为1.4%(m/m),脱色温度60℃,脱色时间52min,在此条件下,附子多糖的平均脱色率为84.99%,与预测值(85.22%)接近;附子多糖的质量浓度为0.018~0.090 mg·mL^(-1)时,对DPPH·和·OH的清除率,最大分别为85.54%和72.64%。

制油工艺对三叶木通籽油活性成分及抗氧化活性的影响

目的:比较不同制油工艺对三叶木通籽油活性成分及氧化活性的影响。方法:以三叶木通籽为原料,采用冷榨法、热榨法、超临界CO_(2)萃取法和浸提法4种油脂制取工艺分别制备三叶木通籽油,分析其脂肪酸组成、活性成分(类胡萝卜素、生育酚、多酚、黄酮)含量,以及其清除DPPH自由基的能力。结果:4种工艺制得的三叶木通籽油脂肪酸组成相近,其中棕榈酸含量在20.62%~21.42%,硬脂酸含量在2.68%~3.08%,油酸含量在47.03%~47.37%,亚油酸含量在27.75%~28.07%,其他脂肪酸含量则均未超过0.5%;在活性成分含量方面,冷榨法制取的三叶木通籽油总生育酚、黄酮和多酚含量均最高,分别达到了349.05,103.37,51.78 mg/kg,而浸提法制取的三叶木通籽油总生育酚、黄酮和多酚含量则显著低于其他3种提取方法,仅220.24,57.73,23.45 mg/kg;在DPPH自由基清除能力方面,冷榨法三叶木通籽油的清除效果最佳、浸提法最差。结论:三叶木通籽油富含油酸和亚油酸,且具有清除DPPH自由基能力。

壳寡糖及其衍生物对CCl_4诱导的小鼠肝损伤的保护作用

研究壳寡糖(COS)、氨基葡萄糖(GlcNH2)和N-乙酰氨基葡萄糖(GlcNAc)对CCl4诱导的雄性昆明种小鼠肝毒性的保护作用,并探讨其可能机制.小鼠腹腔注射CCl4(20 mg/kg体重)24 h后,血清天门冬氨酸转氨酶(AST)和丙氨酸转氨酶(ALT)活性明显提高,引起肝脏脂质过氧化反应,巯基含量降低,总抗氧化能力(T-AOC)减弱,诱发基因毒性.提前连续12天分别灌胃给予COS,GlcNH2和GlcNAc(1.5 g/kg体重)能够显著诱导金属硫蛋白(MT)的表达,体内的抗氧化防御系统随之增强以抵抗CCl4诱导的氧化损伤.血清AST和ALT活性明显降低,肝脏丙二醛(MDA)生成被抑制,巯基含量,T-AOC明显恢复.但是,从DNA电泳结果反应出的基因毒性并未减轻.实验结果证明,提前给予COS,GlcNH2和GlcNAc对CCl4诱导的小鼠肝损伤能够起到有效的保护作用,其中,GlcNH2的作用效果最显著.

苦荞中D-手性肌醇的纯化及其抗氧化活性研究

采用超声浸提法提取苦荞D-手性肌醇(DCI),通过高碘酸钠氧化法测定DCI含量,利用活性炭柱分离纯化苦荞粗提物,高效液相色谱法(HPLC)分析粗提物和纯化产物的组成及含量。以VC、BHT为对照,通过对DPPH自由基、羟自由基、超氧阴离子的体外抗氧化评价体系和总还原力的测定,评价对比苦荞DCI粗提物和纯化产物的抗氧化活性。结果表明,苦荞粗提物中D-手性肌醇的含量仅为0.129%,经活性炭柱纯化后,苦荞中D-手性肌醇的含量可以达到27.26%;苦荞DCI提取物对DPPH自由基、超氧阴离子自由基和羟基自由基均具有不同程度的清除作用,同时具有较好的还原性,且DCI纯化产物的抗氧化活性要明显强于DCI粗提物。

壳寡糖的抗氧化及肝保护功能

目的研究壳寡糖(COS)的抗氧化能力和对CCl4诱导的小鼠肝损伤的保护作用,并初步探讨其作用机制。方法雄性昆明种小鼠,腹腔注射CCl4(20 mg.kg-1)制造肝损伤模型,实验组提前连续12 d灌胃给予COS(1.5 g.kg-1)。小鼠经CCl4损伤24 h后,取血,分离得到血清,测定各组小鼠血清中丙氨酸转氨酶(ALT)和天门冬氨酸转氨酶(AST)的活性。脱颈处死小鼠,取部分肝组织,分别测定肝匀浆中总抗氧化能力(T-AOC)、总巯基(T-SH)和非蛋白结合巯基(NP-SH)含量、金属硫蛋白含量(MT)、丙二醛(MDA)含量和DNA损伤情况等指标。结果COS组与CCl4组相比,ALT、AST活性和MDA含量分别下降了62.2%、52.9%和34.3%。T-AOC和NP-SH含量分别提高了26.1%和16.3%。MT含量是空白对照组的2.15倍。但是没有抑制T-SH含量降低的作用。DNA电泳结果显示,COS组与CCl4组的DNA链都形成一系列1 kb大小左右的DNA片断。结论COS具有抗氧化能力,对CCl4诱导的小鼠肝损伤有较为明显的保护作用,但是不能减轻DNA的氧化性损伤。

小麦胚芽制备抗氧化肽脱色工艺研究

主要研究了粉末活性炭对小麦胚芽酶解液的脱色条件。以脱色率和氮保留率为指标,考察了粉末活性炭的脱色效果,同时测定了脱色对小麦胚芽酶解液抗氧化活性的影响。结果表明,粉末活性炭的最佳脱色条件为:活性炭用量2%,脱色时间30 m in,脱色温度50℃。在此条件下酶解液脱色率为83.9%,氮保留率为60.6%。活性炭脱色会在一定程度上削弱酶解液的抗氧化活性。

板蓝根多糖活性炭脱色工艺及抗氧化活性研究

采用活性炭对板蓝根多糖进行了脱色研究。在单因素实验的基础上进行了正交实验,得到活性炭脱色的最佳工艺条件为:70℃下调节p H为7.0,添加体积分数为1.0%的活性炭,搅拌80 min,脱色率为92.97%、多糖保留率为92.45%。采用DPPH孤电子配对法测定DPPH自由基的清除作用;采用邻苯三酚自氧化法检测超氧阴离子自由基的清除作用。实验结果表明,板蓝根多糖具有一定的清除自由基的能力,但脱色后的多糖清除自由基的能力降低。

超临界CO_2萃取益智油及益智油的抗氧化活性

运用超临界CO2分离技术萃取益智仁中的抗氧化性物质,以l,1-二苯基-2-苦基苯肼(DPPH)清除率和过氧化值为检验指标,采用气相色谱-质谱联用技术分析超临界CO2萃取的益智油的化学成分.分析结果表明,在40℃,15MPa下分离萃取的益智油中含有诺卡酮、益智酮A和益智酮B.不同条件萃取的益智油对花生油的抗氧化性顺序为:40℃,15MPa下的萃取油>2,6-二叔丁基对甲酚(BHT)>35℃,25MPa下的萃取油>50℃,12MPa下的萃取油>35℃,25MPa(乙醇夹带)下的萃取油.超临界CO2萃取所得的益智油对DPPH的清除率明显高于水蒸气萃取油,其中,40℃和15MPa下所得的萃取油对DPPH的清除率最高;高温萃取油对DPPH的清除率有所降低.

氨基葡萄糖对CCl4所致小鼠肝损伤的改善作用

目的:研究氨基葡萄糖(GlcNH2)的抗氧化能力和对CCl4诱导的小鼠肝损伤的改善作用。方法:雄性昆明种小鼠24只随机均分为3组。GlcNH2组每dGlcNH2(1.5g/kg)灌胃;CCl4损伤组和空白对照组每d给予相应体积的生理盐水。前2组于第12天末次给药3h后腹腔注射CCl4(20mg/kg),24h后眼球取血,分别测定各组小鼠血清中丙氨酸转氨酶(ALT)和天门冬氨酸转氨酶(AST)的活性,处死动物后取肝组织,测定肝匀浆中总抗氧化能力(T-AOC),总巯基(T-SH)、非蛋白结合巯基(NP-SH)、金属硫蛋白(MT)、丙二醛(MDA)含量和DNA损伤情况。结果:小鼠腹腔注射CCl424h后,血清AST和ALT活性明显提高,引起肝脏脂质过氧化反应,巯基含量降低,T-AOC减弱,诱发基因毒性。提前连续12d灌胃给予GlcNH2能够显著诱导MT的表达,体内的抗氧化防御系统随之增强以抵抗CCl4诱导的氧化损伤。GlcNH2组与CCl4损伤组相比,AST、ALT活性和MDA含量均明显下降,T-AOC和T-SH、NP-SH、MT含量与CCl4组相比均明显提高。DNA电泳结果显示,GlcNH2组与CCl4组的DNA链都形成一系列1000bp大小左右的DNA片段。结论:GlcNH2具有抗氧化能力,其对CCl4诱导的小鼠肝损伤有较为明显的改善作用,但是不能减轻DNA的氧化性损伤。

超临界CO_2萃取余甘子精油成分及其抗氧化活性研究(英文)

采用超临界CO2萃取余甘子精油,选择萃取压力、温度、时间和甲醇添加量为因素进行正交实验,得出影响精油得率的大小次序为:萃取压力>萃取时间>萃取温度>甲醇添加量,优选出超临界CO2萃取的最佳工艺条件为:萃取压力20 MPa ,萃取温度35 ℃,萃取时间3 h,甲醇添加量10 mL.在这个最佳条件下试验,余甘子精油得率为2·5 %(w/w) .采用DPPH自由基体系和亚油酸过氧化体系测定余甘子精油的抗氧化活性,并运用GC-MS法分析鉴定其化学成分.结果表明,超临界CO2萃取的余甘子精油具有较强的抗氧化活性,其清除DPPH自由基的活性优于维生素E和合成抗氧化剂BHA,抑制亚油酸过氧化的能力优于维生素E;从该精油中鉴定出了30种化学成分,其中主要成分为β波旁烯(30·15 %)、丁香酚(8·25 %)、β丁香烯(8·56 %)、二十四醇(14·42 %)及十七烷醇(2·92 %) ,初步推断甲基丁香酚、β丁香烯、β波旁烯为主要的抗氧化成分.余甘子精油具有较强的抗氧化作用,可望开发成为天然食品抗氧化剂.

反应热压烧结制备ZrB_2-SiC复合陶瓷的高温抗氧化性能研究

以硅和活性碳为添加剂,在1850℃、20MPa条件下,利用反应热压烧结工艺制备出了ZrB2-SiC陶瓷基复合材料。复合材料在1500℃下进行高温氧化处理,研究了添加剂含量对ZrB2陶瓷抗氧化性能的影响。借助X射线衍射和扫描电镜分析了复合材料氧化前后物相组成和微观结构的变化规律,并对复合材料的抗氧化机理进行了探讨。研究结果表明:纯ZrB2陶瓷在氧化过程中形成多孔ZrO2层,其抗氧化性较差,而含SiC的复合陶瓷在氧化过程中,样品表面形成致密的富SiO2玻璃层,能显著提高复合材料的抗氧化性。

纳米碳点对花生幼苗生长及其相关生理生化指标的影响

在室内水培条件下,研究了不同质量浓度的纳米碳点对花生幼苗生长及相关生理生化指标的影响。结果表明,不同质量浓度的纳米碳点处理对花生种子萌发、幼苗生长、根系活力和抗氧化酶活性等均有不同程度的促进作用,且随着纳米碳点质量浓度的升高,花生种子的发芽势、发芽率、主根长、苗高、根干质量、地上部干质量、根系活力及幼苗的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性均表现出先升高后降低的趋势;此外,不同质量浓度的纳米碳点处理可降低花生幼苗中丙二醛(MDA)的含量,增加花生幼苗可溶性糖的含量。在各处理中,以纳米碳点质量浓度为180 mg/L时使用效果最佳,与CK相比,该处理花生幼苗的主根长、苗高、根干质量、地上部干质量、根鲜质量、地上部鲜质量、SOD活性、CAT活性分别比CK增加了36.84%,46.24%,31.03%,47.03%,55.93%,42.22%,22.73%,36.81%,而根系活力则提高了4.5倍。研究表明,适宜质量浓度的纳米碳点可以调节花生幼苗生理生化过程,促进幼苗的生长。