不同pH值下MgO NPs悬浮液中Mg^(2+)质量浓度的动态变化及其对小麦生长的影响

MgO NPs在广泛应用的同时会进入到植物的生长环境中,环境的pH值也会影响纳米粒子中金属离子的释放及其与植物间的相互作用。本文选择我国种植面积较大的农作物—小麦(Triticum aestivum L.)为受试对象,使用镁离子选择性微电极研究不同pH值时MgO NPs悬浮液中Mg^(2+)质量浓度的动态变化及其对小麦生长的影响。结果表明,MgO NPs悬浮液中Mg^(2+)质量浓度随时间逐渐增大,48 h后趋于稳定。调节pH值至悬浮液呈酸性促进了Mg^(2+)的释放,对于80 mg/L的MgO NPs悬浮液,pH=6.5时Mg^(2+)质量浓度由未调节pH值时的24.31 mg/L增加到31.47 mg/L。与此同时,小麦对Mg^(2+)的吸收增加,从而在一定程度上减轻了MgO NPs对小麦生长的抑制作用。

MgO纳米颗粒对油菜子叶外植体的影响

MgO纳米颗粒(MgO NPs)是在药剂、污染修复、涂料及半导体等中得到广泛应用的无毒环保材料,以油菜(Brassica napusL.)品种‘宁油12’培养于MS培养基上4—5 d的子叶外植体为供体材料,在添加0—10.0 mmol∕L MgO NPs的油菜不定芽再生培养基(MS+4.5 mg∕L 6-BA)上培养21 d。结果表明:1.5 mmol∕L MgONPs处理的子叶外植体不定芽再生频率和单个外植体平均不定芽数均达最高值,分别为83.33%和19.33个,显著高于对照;0.5—1.5 mmol∕L MgO NPs处理显著提高了子叶不定根的再生频率;超过2.0 mmol∕L,对外植体有明显抑制效应;超过8.0 mmol∕L,外植体完全失去再生能力。但在4.0 mmol∕L时,从子叶不定根再生频率以及外植体质量上看,较2.0 mmol∕L时的活力有明显提高,可能存在纳米颗粒团聚效应降低了高浓度MgO NPs对外植体再生的抑制效应。以上结果表明:低浓度MgO NPs处理对油菜子叶外植体再生有显著促进作用,但超过2.0 mmol∕L表现出明显的毒害效应。低浓度MgO NPs亦可作为组培上值得尝试的价廉环保的添加剂。

An efficient and comparative adsorption of Congo red and Trypan blue dyes on MgO nanoparticles: Kinetics, thermodynamics and isotherm studies

Cubic phase of Mg O nanoparticles were prepared by microwave-assisted combustion synthesis and investigated for the removal of toxic dyes like Congo Red(CR)and Trypan blue(TB).The crystallite size of the Mg O nanoparticle was calculated to be 18 nm from XRD pattern.The sample was further characterized by FTIR,TGA and FESEM techniques.The dyes were subjected to prototypical batch adsorption process,including investigation of different parameters like Mg O dosage,dye concentration,solution pH,agitation speed and temperature.It was found that,0.2 g of Mg O NPs showed maximum removal efficiency for both the dyes(more than 98%),having 25 ppm of dye concentration at an acidic p H(3–4).The maximum loading capacity of Mg O NPs was obtained to be 136 mg/g and 132 mg/g for CR and TB,respectively.Different thermodynamic parameters like△G^(0),△H^(0)and△S^(0)were measured.The negative△H^(0)and the positive△S^(0)values for both the dyes correspond to an exothermic process and an increase in randomness of the adsorbent and dye.The isotherm analysis exhibited that the Freundlich model fits better to the experimental equilibrium data,suggesting heterogeneous surface of the nanoparticles.Whereas,the kinetic data revealed a pseudo 2 nd order rate for adsorption process.

纳米氧化镁对柑橘炭疽菌的抗菌效应

纳米氧化镁(MgO NP)因其自身卓越的物理化学性质,尤其是较高的比表面积,使其在光学、电学、材料学和生物医学等各个领域都表现出重要的应用前景.MgO NP对细菌表现出良好的抗菌性,而对真菌的抗菌性研究较少.本文研究了MgO NP对柑橘炭疽病菌胶孢炭疽菌(Colletotrichum gloeosporioides)的抗菌作用,测定了其对胶孢炭疽菌的菌丝生长和菌丝形态的影响,以及对孢子萌发的抑制作用,并测定了MgO NP对柑橘炭疽病的防控效果.研究结果表明,100~800μg/mL的MgO NP都能较好抑制胶孢炭疽菌菌丝生长和孢子萌发,其中400μg/mL和800μg/mL剂量效果最明显;同时提前施用400μg/mL的MgO NP表现出较好的柑橘炭疽病防治效果,说明MgO NP具有作为植物保护剂的潜力.