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排序方式: 共有174条查询结果,搜索用时 875 毫秒
171.
Haihua Wang Yonghao Ni M. Sarwar Jahan Zehua Liu Thioni Schafer 《Journal of Thermal Analysis and Calorimetry》2011,103(1):293-302
The thermo-oxidative stability of acetic acid lignin-containing polyurethane (LPU) that contains cross-linking agents, such
as 1-aminopropyltriethoxy-silane (APTS) and/or trimethylolpropane (TMP) was investigated based on the thermogravimetric analysis
(TGA) method, their kinetic parameters in the thermo-oxidative process was determined. FT-IR certified the occurrence of interaction
between lignin and polyurethane (PU). It was found that continuous membrane can be formed when lignin concentration was 43.3%,
but rupture took place when it increased to 50%. When the degradation was performed in nitrogen, TG and dynamic differential
thermogravimetry (DTG) results demonstrated that the PU underwent three stages of degradation while the LPU involved one main
degradation stage with a shoulder, and the degradation stability increased with the increase in the lignin concentration and
PEG length. It was also found that the addition of a cross-linking agent is beneficial to the improvement of thermal stability
and, in particular, APTS gave the best thermal stability for the LPU produced, among the cross-linking agents tested. Furthermore,
LPU exhibited multistage degradation process in air and displayed higher thermo-oxidative stability than PU. At the same time,
the kinetic study showed that LPU modified with APTS exhibited higher activation energy than LPU modified with TMP. And the
maximum activation energy was found for the sample modified with the simultaneous addition of APTS and TMP. 相似文献
172.
Seyedeh Zeinab Mousavi‐Sani Jahan Bakhsh Raoof Reza Ojani Ezat Hamidi‐Asl 《中国化学会会志》2013,60(6):650-656
In this paper, nano‐gold modified carbon paste electrode (NGMCPE) was employed to develop an electrochemical DNA hybridization biosensor. The proposed sensor was made up by immobilization of 15‐mer single stranded oligonucleotide probe for detection of target DNA. Hybridization detection relies on the alternation in guanine oxidation signal following hybridization of the probe with complementary genomic DNA. The guanine oxidation was monitored using differential pulse voltammetry (DPV). Different factors such as activation potential, activation time and probe immobilization conditions were optimized. The selectivity of the sensor was investigated by non‐complementary oligonucleotides. Diagnostic performance of the biosensor was described and the detection limit was found 1.9 × 10?13 M at the NGMCPE surface. All of the investigations were performed in both CPE and NGMCPE and finally their results were compared. 相似文献
173.
A carbon‐paste electrode modified with 2,7‐bis(ferrocenyl ethyl)fluoren‐9‐one and carbon nanotubes was used for the sensitive voltammetric determination of levodopa (LD). The electrochemical response characteristics of the modified electrode toward LD, uric acid (UA) and folic acid (FA) were investigated. The results showed an efficient catalytic activity of the electrode for the electrooxidation of LD, which leads to lowering its overpotential by more than 320 mV. The modified electrode exhibits an efficient electron mediating behavior together with well‐separated oxidation peaks for LD, UA and FA. Also, the modified electrode was used for determination of LD in some real samples. 相似文献
174.
Md. Sazzad Hossain Adolfo I. B. Romo Seth T. Putnam Jahan Dawlaty Veronica Augustyn Joaquín Rodríguez-López 《Angewandte Chemie (International ed. in English)》2023,62(24):e202304218
Recently, non-Faradaic effects were used to modify the electronic structure and reactivity of electrode-bound species. We hypothesize that these electrostatic perturbations could influence the chemical reactivity of electrolyte species near an electrode in the absence of Faradaic electron transfer. A prime example of non-Faradaic effects is acid-base dissociation near an interface. Here, we probed the near-electrode dissociation of N-heterocycle-BF3 Lewis adducts upon electrode polarization, well outside of the redox potential window of the adducts. Using scanning electrochemical microscopy and confocal fluorescence spectroscopy, we detected a potential-dependent depletion of the adduct near the electrode. We propose an electro-inductive effect where a more positive potential leads to electron withdrawal on the N-heterocycle. This study takes a step forward in the use of electrostatics at electrochemical interfaces for field-driven electrocatalytic and electro-synthetic processes. 相似文献