模拟低温对龙眼果实发育及其果皮H_2O_2代谢的影响

以3年生‘储良’龙眼盆栽树为试验材料,于花后28 d时采取模拟低温(昼夜15/10℃)处理,研究该处理对龙眼果实发育及其果皮过氧化氢(H_2O_2)含量、过氧化物酶(POD)活性与过氧化氢酶(CAT)活性的影响,以常温(昼夜28/23℃)处理为对照。结果表明:模拟低温处理后的龙眼成熟果实单果重明显偏小、发育期显著增加,主要是延长了果实发育前期,但其累积落果率与对照差异不显著。模拟低温期间,果实生长缓慢,落果较少,果皮POD、CAT活性与H_2O_2含量均低于对照;但从处理后43 d起开始解除模拟低温后,果实发育迅速,落果剧烈,果皮POD、CAT活性及H_2O_2含量均呈先升后降的变化趋势,且在果实发育中后期均明显高于对照。这表明,模拟低温抑制了果实生长、延长了果实发育期,温度骤然回升引起果皮H_2O_2的爆发及果皮抗氧化酶活性的提高,进而诱导了果实大量脱落。     

电荷辅助氢键对腐殖酸分子量和溶解性的影响

采用体积排阻色谱和总有机碳分析法,分别测定腐殖酸体系中加入盐酸、甲酸、乙酸和丙酸后其分子量和溶解性发生的变化;通过分析抗坏血酸、苯甲酸、苯酚和邻苯二酚4种模型化合物在甲酸影响下的紫外光谱,以验证电荷辅助氢键的存在。结果表明:小分子有机酸能够明显降低腐殖酸的分子量;此外,当腐殖酸体系pH接近小分子有机酸的pKa时(DpKa<0.5),腐殖酸溶解性明显增大。小分子有机酸可能与腐殖酸之间形成电荷辅助氢键,从而打破弱作用力维持的腐殖酸超分子的稳态结构,导致腐殖酸分子量的降低和溶解性的增加;且弱酸与有机物之间的pKa相差越小,形成的电荷辅助氢键能量越高,腐殖酸分子结构受到的扰动程度越大。一维紫外光谱和同步二维相关紫外光谱分析进一步表明,小分子有机酸可能与pKa接近的化合物之间形成电荷辅助氢键,整体跃迁所需能量提高,造成低波长吸收增大而高波长吸收减小的结果。     

采用麦饭石和双氧水改善扇贝育苗用水水质的研究

研究了麦饭石和过氧化氢作为水质净化剂对水体中水化因子的调控作用和效果,结果表明:双氧水能有效去除水中有机物,且基本无残留;麦饭石对养殖水体具有双向调节酸碱度的作用,能有效降低水体中的有害物质含量,麦饭石的一次使用量为50 mg/L,一次效应为8天左右。随着使用量的提高,水体中的NH_4~ -N和NO_2~--N的浓度降低的效果更为明显,且效用时间更长,尤其是在水质恶化时其作用更为明显。     

硼酸铵-磷酸氢二铵协效阻燃杨木单板的制备与表征研究

利用极限氧指数、水平垂直燃烧测试、热重分析(TGA)和扫描电镜(SEM)比较研究了硼酸铵与磷酸氢二铵复配阻燃杨木单板的阻燃性能及热解特性。结果表明：磷酸氢二铵的阻燃性能优于硼酸铵,两者复配使用时具有明显的协效性;质量浓度为20%的复合阻燃剂溶液处理杨木单板的氧指数和残炭量最高,分别为61%和53.5%,在水平垂直燃烧试验中也显现出优异的阻燃性能;复合阻燃剂降低了热解阶段的初始分解温度、峰值分解温度和各阶段的表观活化能;燃烧后的SEM分析表明,阻燃剂的加入使得杨木单板在燃烧过程中形成了保护层,有效阻止了热和氧气的交换,从而提高了杨木单板的阻燃性能。     

过氧化氢诱导BRL细胞凋亡损伤模型的建立

动物冷应激过程中肝脏因发生氧化应激而受损。本试验采用过氧化氢(H2O2)诱导buffalo大鼠肝细胞(BRL)凋亡,建立体外氧化应激的凋亡损伤模型,为深入研究冷应激对肝脏损伤的机理奠定基础。试验采用不同浓度H2O2刺激BRL细胞2h,运用WST-1法检测细胞生长活力、Annexin-V/FITC-PI双染技术检测细胞凋亡率及Western blot方法检测Caspase-3的表达量来筛选BRL细胞凋亡的H2O2作用浓度。结果显示,与空白对照组相比,150μmol/L H2O2作用后,细胞增殖率明显下降,Caspase-3的蛋白表达量增加,流式细胞仪检测的凋亡率升高,同时细胞坏死较其他H2O2处理组低。结果表明,150μmol/L H2O2作用BRL细胞2h可模拟氧化应激造成的凋亡损伤。     

基于稳定同位素的黄土塬区村庄涝池对地下水补给的定量分析

[目的] 定量研究黄土塬区村庄涝池对地下水的补给情况,为地下水资源持续利用提供理论依据。[方法] 通过测定长武黄土塬区村庄涝池和农田深剖面土壤湿度及土壤水氢氧稳定同位素组成,利用同位素示踪技术计算村庄涝池对地下水的补给量。[结果] ①涝池深剖面土壤水分平均值为25.5%,大于农田深剖面土壤湿度（20.6%）; ②涝池土壤水的δD值介于-117.83‰~-56.66‰之间,δ¹⁸O值介于-16.63‰~-7.72‰之间,农田土壤水的δD介于-81.76‰~-52.03‰之间,δ¹⁸O值介于-10.64‰~-6.35‰之间;与农田相比,涝池土壤水分受蒸发影响较小,同位素组成偏负,且变幅较大; ③涝池土壤水同位素剖面保留了较大降水事件的同位素信号,表明涝池水通过活塞流形式对地下水进行了补给,活塞流速度为0.26 m/d;在涝池集水区内,地下水年均潜在补给量为134 mm,占年降水量的23.1%。[结论] 黄土塬区涝池是地下水重要的补给来源。因此,应加强涝池保护、恢复和重建工作,确保该区地下水的持续补给和利用。     

硫酸盐法竹浆无元素氯漂白的研究

研究了硫酸盐法竹浆低二氧化氯用量的DQP漂白中各个漂段的影响因素,并对D段终点pH值、Q段EDTA用量以及P段MgSO4用量进行优化.结果表明:当D段终点pH值为4,Q段EDTA用量为0.2%,P段MgSO4用量为0.02%(以Mg2+计),DQP漂白效果较好.仅用1.5%的有效氯(0.57%的ClO2)和1.5%的H2O2,就可将硫酸盐竹浆漂到83%ISO的白度.还对竹浆DQP和CEH漂白的漂终结果、纸浆强度性质以及废水特性进行了比较.结果表明:与CEH漂白相比,DQP漂白浆的白度稍低,但白度稳定性好,纸浆粘度高,强度性质较好,对环境污染较小.     

Mobilization of seed reserves pretreated with H2O2 during germination and establishment of sunflower seedlings under salinity

Abstract

Several studies have shown hydrogen peroxide (H₂O₂) as a metabolic messenger that increases plant tolerance to various stress conditions. However, little is known about its effect on the mobilization of seed reserves in the establishment of seedlings. Thus, this study aimed to evaluate the effect of pretreatment with H₂O₂ in salt-tolerance and mobilization of reserves during the germination of seeds and establishment of sunflower seedlings. Seeds were pre-imbibed for 24?hr in solutions containing: deionized water (control); H₂O₂ (1?mM); NaCl (100?mM). Subsequently, seeds were distributed on germitest paper, moistened with deionized water or saline solution (100?mM NaCl). In seedlings not pretreated with H₂O₂, the salinity increased Na⁺ and Cl^? ions contents and reduced the growth of sunflower seedlings. However, pretreatment of seeds with H₂O₂ reduced the negative effect of salinity, promoted an increase in salt-tolerance by the reduction of Na⁺ and Cl^? uptake, lower energy cost for osmoprotection by compatible solutes accumulation, and by the higher equilibrium in the mobilization of the cotyledon reserves for the development of the embryonic axis.     

Endogenous hydrogen sulfide results in increase of reactive oxygen species induced by angiotensin II in neurons

AIM：To determine the effect of endogenous hydrogen sulfide (H2S) on the production of reactive oxygen species (ROS) in medullary neurons induced by angiotensin II (Ang II). METHODS：Primary cultured rat medullary neurons were used in the study. Identification of medullary neurons and the co-expression of cystathionine β-synthetase (CBS) were detected by double-labeling immunofluorescence. Medullary neurons were treated with Ang II in the presence or absence of sodium butyrate (NaBu, a CBS agonist; 100 μmol/L, 250 μmol/L and 500 μmol/L). ROS production was measured by dihydroethidium staining. The activity of total superoxide dismutase (SOD) was detected by ELISA. The mRNA expression of CBS was determined by real-time PCR. RESULTS：The medullary neurons in the cultured cells were over 90%. Ang II (1 μmol/L) significantly increased ROS level in the medullary neurons. Ang II inhibited the activity of total SOD in the medullary neurons. CBS was expressed in the medullary neurons. Ang II decreased the mRNA expression of CBS. NaBu (250 μmol/L and 500 μmol/L) inhibited ROS production induced by Ang II with a dose-dependent manner, while NaBu alone had no influence on the ROS level in the medullary neurons. CONCLUSION：Ang II increases the level of ROS in medullary neurons partly by inhibiting the activity of total SOD and the mRNA expression of CBS. Endogenous H2S inhibits the ROS level increased by Ang II in the medullary neurons.