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951.
石墨烯-壳聚糖修饰玻碳电极应用于环境水中五氯酚的测定 总被引:1,自引:0,他引:1
制备了石墨烯(CRG)-壳聚糖(CS)修饰玻碳(CRG-CS/GC)电极,用循环伏安法和示差脉冲伏安法研究了五氯酚(PCP)的电化学行为,发现其氧化电流信号与GC电极相比明显增强,表明修饰电极对PCP具有较强的吸附作用,并能够加速电子传递。 建立了一种灵敏简便、重现性好、稳定性好的测定PCP的新修饰电极方法,线性响应范围为1.00×10-7~1.00×10-5 mol/L(R=0.9975),检测限为2.3×10-8 mol/L(S/N=3)。 将该修饰电极应用于实际水样分析,回收率为97%~103%。 相似文献
952.
We report on a sensitive electrochemical sensor for dopamine (DA) based on a glassy carbon electrode that was modified with a nanocomposite containing electrochemically reduced graphene oxide (RGO) and palladium nanoparticles (Pd-NPs). The composite was characterized by scanning electron microscopy, energy dispersive spectroscopy, and electrochemical impendence spectroscopy. The electrode can oxidize DA at lower potential (234 mV vs Ag/AgCl) than electrodes modified with RGO or Pd-NPs only. The response of the sensor to DA is linear in the 1–150 μM concentration range, and the detection limit is 0.233 μM. The sensor was applied to the determination of DA in commercial DA injection solutions. Figure
Schematic representation showing the oxidation of DA at RGO-Pd-NPs composite electrode. 相似文献
953.
954.
Róbert Berkecz István Ilisz Aleksandra Misicka Dagmara Tymecka Ferenc Fülöp Hee Jung Choi Myung Ho Hyun Antal Péter 《Journal of separation science》2009,32(7):981-987
RP high‐performance liquid chromatographic methods were developed for the enantioseparation of eleven unusual β2‐homoamino acids. The underivatized analytes were separated on a chiral stationary phase containing (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid as chiral selector. The effects of organic (alcoholic) and acidic modifiers, the mobile phase composition and temperature on the separation were investigated. The structures of the substituents in the α‐position of the analytes substantially influenced the retention and resolution. The elution sequence was determined in some cases: the S enantiomers eluted before the R enantiomers. 相似文献
955.
Park YB Kim YY Oh SK Chung SG Ku SY Kim SH Choi YM Moon SY 《Experimental & molecular medicine》2008,40(1):98-108
Human embryonic stem cells (hESCs) are considered to be able to stably maintain their characteristics in vitro for prolonged periods, but we had previously encountered changes in proliferative ability and differentiation potential during extended culture of hESCs. Therefore, we investigated the proliferative ability and differentiation potential of hESCs during long-term culture. The hESCs, SNUhES3, were used to analyze population-doubling time, proliferation rate and differentiation potential. We classified hESCs into three groups according to culture period. Ten colonies of hESCs for each group were daily measured colony area and population-doubling time was assessed by the changes of colony area. Proliferation rate of hESCs was measured by 5-bromo-2'-deoxyuridine (BrdU) assay and telomerase activity. To evaluate differentiation potentials for hESCs, expression levels of undifferentiated and/or differentiated hESCs markers were examined by FACS, RT-PCR and immunostaining. Population-doubling time of early passage hESCs was longer than those of middle or late passage. Proliferative ability of hESCs was accelerated depending on culture periods. Cellular morphologies and the expression level of each three germ layer markers were obviously different from each passage of reattached embryoid bodies (EBs) after spontaneous differentiation. Differentiated cells of late passage expressed higher levels of undifferentiated markers such as Oct4 and SSEA4 than those of early and middle passage. But differentiated cells of early and middle passage expressed higher level of differentiated state markers, Nestin (ectoderm), Brachyury (mesoderm), HNF3beta (endoderm). From these results, it can be inferred that hESCs show higher proliferative abilities and reduced differentiation potentials as the passage number increased. Therefore, we conclude that early passage hESCs could be more suitable than middle and late passage hESCs in differentiation studies. 相似文献
956.
Effect of phase stability degradation of bismuth on sensor characteristics of nano-bismuth fixed electrode has been investigated using square-wave anodic stripping voltammetry technique, scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectroscopy. From the analyses of square-wave anodic stripping voltammograms (SWASV) repetitively measured on the nano-bismuth fixed electrode, it was found that the oxidation peak currents dropped by 81%, 68% and 59% for zinc, cadmium and lead, respectively, after the 100th measurement (about 400 min of operation time). The sphere bismuth nanoparticles gradually changed to the agglomerates with petal shape as the operation time increased. From the analyses of SEM images and XRD patterns, it is confirmed that the oxidation of Bi into BiOCl/Bi2O2CO3 and the agglomeration of bismuth nanoparticles caused by the phase change decrease a reproducibility of the stripping voltammetric response. Moreover, most of the bismuth becomes BiOCl at pH 3.0 and bismuth hydroxide, Bi(OH)3 at pH 7.0, which results in a significant decrease in sensitivity of the nano-bismuth fixed electrode. 相似文献
957.
K. Miernik W. Dominik Z. Janas M. Pfützner L. Grigorenko C. Bingham H. Czyrkowski M. ?wiok I. G. Darby R. Da?browski T. Ginter R. Grzywacz M. Karny A. Korgul W. Ku?mierz S. N. Liddick M. Rajabali K. Rykaczewski A. Stolz 《The European Physical Journal A - Hadrons and Nuclei》2009,42(3):431-439
The decay of the extremely neutron-deficient isotope 45Fe has been studied by using a new type of gaseous detector in which a technique of optical imaging is used to record tracks of charged particles. The two-proton radioactivity and the $ \beta$ -decay channels were clearly identified. For the first time, the angular and energy correlations between two protons emitted from the 45Fe ground state were measured. The obtained results were confronted with predictions of a three-body model. 相似文献
958.
Dr. Piotr Winiarz Kacper Dzierzgowski Dr. Aleksandra Mielewczyk-Gryń Prof. Maria Gazda Dr. Sebastian Wachowski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(17):5393-5398
Lanthanum orthoantimonate was synthesized using a solid-state synthesis method. To enhance the possible protonic conductivity, samples with the addition of 1 mol % Ca in La-site were also prepared. The structure was studied by the means of X-ray diffraction, which showed that both specimens were single phase. The materials crystallized in the space group P21/n. Dilatometry revealed that the material expanded non-linearly with the temperature. The nature of this deviation is unknown; however, the calculated linear fraction thermal expansion coefficient was 9.56×10−6 K−1. Electrical properties studies showed that the material is a proton conductor in oxidizing conditions, which was confirmed both by temperature studies in wet in dry air, but also by the H/D isotope exchange experiment. The conductivity was rather modest, peaking at the order of 10−6 S cm−1 at 800 °C, but this could be further improved by microstructure and doping optimization. This is the first time protonic conductivity in lanthanum orthoantimonates is reported. 相似文献
959.
The typical form of the low-field magnetoresistance anomaly induced by a strong one-dimensional periodic modulation of the background potential is described. It is shown that the magnetoresistance peak due to the magnetic breakdown is always followed by a resistance increase at higher magnetic fields, for which οcτ > 1. 相似文献
960.
Kleperis Jānis Bajārs Gunārs Grīnberga Līga Vaivars Guntars Purāns Juris Vītiņš Ģirts Kučinskis Gints 《Journal of Solid State Electrochemistry》2023,27(7):1641-1660
Journal of Solid State Electrochemistry - Solid state ionics is one of the key research topics of the Institute of Solid State Physics, University of Latvia since its establishment. The research... 相似文献