Controlled synthesis of functional photoluminescent materials are of particular interest due to their fascinating optical properties. Herein, highly uniform SiO2:xTb3+spherical nanoparticles are fabricated by a facile...Controlled synthesis of functional photoluminescent materials are of particular interest due to their fascinating optical properties. Herein, highly uniform SiO2:xTb3+spherical nanoparticles are fabricated by a facile sol-gel method. The structure, morphology, compositions, and luminescence properties of As-prepared samples were well investigated using TEM, SEM, EDX, XRD, XPS and luminescence spectroscopy. The PL intensity of SiO2:xTb3+spherical nanoparticles is Tb3+ ions concentration dependent achieved a maximum at 3 mol % of Tb3+. Particularly, SiO2:xTb3+spherical nanoparticles exhibit a green emission corresponding to 5D4→7Fj transition (541 nm) of Tb3+. These results show that As-prepared phosphors may find potential application in solid-state lighting fields.展开更多
To understand and improve the stability of the insecticidal activity of tobacco extract,the 3 rd instar larvae of Malacosoma neustria testacea was determined by the leaf film method.Spectrophotometry identified extrac...To understand and improve the stability of the insecticidal activity of tobacco extract,the 3 rd instar larvae of Malacosoma neustria testacea was determined by the leaf film method.Spectrophotometry identified extract effects on activities of several enzymes.In addition,to improve the stability of the extract,microcapsules were prepared by complex coacervation and phase separation with the extract as core material,and gelatin and gum arabic as wall material.With the embedding rate as the evaluation index,the response surface method was used to optimize the preparation process of the microcapsules.The results show that the extract had a strong insecticidal activity on the larvae,with inhibitory effects on several enzymes examined of carboxylesterase,acetylcholinesterase,glutathione-S transferase,catalase,and superoxide dismutase.The inhibition rate increased with time.The best preparation process of tobacco extract microcapsules was 25% mass fraction of emulsifier,2.05% mass fraction of gelatin,3% mass fraction of gum arabic,1.34 wall core ratio,36 min of complex coacervation time.The embedding rate was 58.4% which is approximately the theoretical embedding rate(58.9%).The microcapsules prepared by this method have a smooth surface,good combining form and particle size distribution,and a median diameter of 8.6 μm.Infrared characteristic peaks of the extracts were preserved at 877.55 cm^(-1) and2922.13 cm^(-1).Microencapsulation can improve the thermal stability of the tobacco extract.Indoor toxicity tests showed that LC_(50) of extract microcapsules was 20.2 mg·mL^(-1),equivalent to the toxicity level of the tobacco extract itself,indicating that microencapsulation did not reduce extract insecticidal effects.This research may provide a reference for the optimization of the tobacco extract microcapsule preparation process.展开更多
Controlled synthesis of functional photoluminescent materials is of particular interest due to their fascinating optical properties. Herein, highly uniform one-dimensional (1D) SiO2:xTb3+ nanofibers and nanobelts are ...Controlled synthesis of functional photoluminescent materials is of particular interest due to their fascinating optical properties. Herein, highly uniform one-dimensional (1D) SiO2:xTb3+ nanofibers and nanobelts are fabricated by electrospinning method combined with sol-gel method. The as-prepared SiO2:xTb3+ nanofibers are belt-like morphology after calcination. The formation mechanism of SiO2:xTb3+ nanofibers and nanobelts is proposed based on decomposition of polyvinylpyrrolidone (PVP) and crystallization of SiO2. The photoluminescence (PL) intensity of SiO2:xTb3+ nanofibers and nanobelts is Tb3+ ions concentration dependent with a maximum at 4 mol% of Tb3+. Particularly, SiO2:xTb3+ nanofibers and nanobelts exhibit a green emission corresponding to 5D4 → 7Fj transition (541 nm) of Tb3+.展开更多
文摘Controlled synthesis of functional photoluminescent materials are of particular interest due to their fascinating optical properties. Herein, highly uniform SiO2:xTb3+spherical nanoparticles are fabricated by a facile sol-gel method. The structure, morphology, compositions, and luminescence properties of As-prepared samples were well investigated using TEM, SEM, EDX, XRD, XPS and luminescence spectroscopy. The PL intensity of SiO2:xTb3+spherical nanoparticles is Tb3+ ions concentration dependent achieved a maximum at 3 mol % of Tb3+. Particularly, SiO2:xTb3+spherical nanoparticles exhibit a green emission corresponding to 5D4→7Fj transition (541 nm) of Tb3+. These results show that As-prepared phosphors may find potential application in solid-state lighting fields.
基金funded by the Fundamental Research Funds for the Central Universities (2572019AA04)the Central Financial Fund for Forestry Science and Technology Promotion (JLT[2019]HZT02)the Forestry Science and Technology Project of Key State-owned Forest Management Bureau in Daxing 'anling,Inner Mongolia (2018003)。
文摘To understand and improve the stability of the insecticidal activity of tobacco extract,the 3 rd instar larvae of Malacosoma neustria testacea was determined by the leaf film method.Spectrophotometry identified extract effects on activities of several enzymes.In addition,to improve the stability of the extract,microcapsules were prepared by complex coacervation and phase separation with the extract as core material,and gelatin and gum arabic as wall material.With the embedding rate as the evaluation index,the response surface method was used to optimize the preparation process of the microcapsules.The results show that the extract had a strong insecticidal activity on the larvae,with inhibitory effects on several enzymes examined of carboxylesterase,acetylcholinesterase,glutathione-S transferase,catalase,and superoxide dismutase.The inhibition rate increased with time.The best preparation process of tobacco extract microcapsules was 25% mass fraction of emulsifier,2.05% mass fraction of gelatin,3% mass fraction of gum arabic,1.34 wall core ratio,36 min of complex coacervation time.The embedding rate was 58.4% which is approximately the theoretical embedding rate(58.9%).The microcapsules prepared by this method have a smooth surface,good combining form and particle size distribution,and a median diameter of 8.6 μm.Infrared characteristic peaks of the extracts were preserved at 877.55 cm^(-1) and2922.13 cm^(-1).Microencapsulation can improve the thermal stability of the tobacco extract.Indoor toxicity tests showed that LC_(50) of extract microcapsules was 20.2 mg·mL^(-1),equivalent to the toxicity level of the tobacco extract itself,indicating that microencapsulation did not reduce extract insecticidal effects.This research may provide a reference for the optimization of the tobacco extract microcapsule preparation process.
文摘Controlled synthesis of functional photoluminescent materials is of particular interest due to their fascinating optical properties. Herein, highly uniform one-dimensional (1D) SiO2:xTb3+ nanofibers and nanobelts are fabricated by electrospinning method combined with sol-gel method. The as-prepared SiO2:xTb3+ nanofibers are belt-like morphology after calcination. The formation mechanism of SiO2:xTb3+ nanofibers and nanobelts is proposed based on decomposition of polyvinylpyrrolidone (PVP) and crystallization of SiO2. The photoluminescence (PL) intensity of SiO2:xTb3+ nanofibers and nanobelts is Tb3+ ions concentration dependent with a maximum at 4 mol% of Tb3+. Particularly, SiO2:xTb3+ nanofibers and nanobelts exhibit a green emission corresponding to 5D4 → 7Fj transition (541 nm) of Tb3+.
