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排序方式: 共有361条查询结果,搜索用时 15 毫秒
131.
Filip J Yngard RA Siskova K Marusak Z Ettler V Sajdl P Sharma VK Zboril R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(36):10097-10105
The reaction of potassium ferrate(VI), K2FeO4, with weak‐acid dissociable cyanides—namely, K2[Zn(CN)4], K2[Cd(CN)4], K2[Ni(CN)4], and K3[Cu(CN)4]—results in the formation of iron(III) oxyhydroxide nanoparticles that differ in size, crystal structure, and surface area. During cyanide oxidation and the simultaneous reduction of iron(VI), zinc(II), copper(II), and cadmium(II), metallic ions are almost completely removed from solution due to their coprecipitation with the iron(III) oxyhydroxides including 2‐line ferrihydrite, 7‐line ferrihydrite, and/or goethite. Based on the results of XRD, Mössbauer and IR spectroscopies, as well as TEM, X‐ray photoelectron emission spectroscopy, and Brunauer–Emmett–Teller measurements, we suggest three scavenging mechanisms for the removal of metals including their incorporation into the ferrihydrite crystal structure, the formation of a separate phase, and their adsorption onto the precipitate surface. Zn and Cu are preferentially and almost completely incorporated into the crystal structure of the iron(III) oxyhydroxides; the formation of the Cd‐bearing, X‐ray amorphous phase, together with Cd carbonate is the principal mechanism of Cd removal. Interestingly, Ni remains predominantly in solution due to the key role of nickel(II) carbonate, which exhibits a solubility product constant several orders of magnitude higher than the carbonates of the other metals. Traces of Ni, identified in the iron(III) precipitate, are exclusively adsorbed onto the large surface area of nanoparticles. We discuss the relationship between the crystal structure of iron(III) oxyhydroxides and the mechanism of metal removal, as well as the linear relationship observed between the rate constant and the surface area of precipitates. 相似文献
132.
We report on an optical characterisation of nanocrystalline diamond films photochemically functionalised with the organosilane-coupling
agent, N
1-(3-(trimethoxysilyl)propyl)hexane-1,6-diamine (alternative names: N-(6-aminohexyl)aminopropyl-trimethoxysilane, (3-(6-aminohexylamino)propyl) trimetoxysilane, AHAPS). The presence and homogeneity
of the organosilane layers were detected by fluorescence microscopy and infrared reflectance-absorbance spectroscopy. The
results indicated that a homogeneous surface coverage with organosilane layers was achieved on diamond surfaces which were
modified either by hydrogen or by oxygen plasma treatment. The functionalised nanocrystalline diamonds present a promising
solution in future biosensor applications. 相似文献
133.
Kurihara H Lu X Iiduka Y Mizorogi N Slanina Z Tsuchiya T Nagase S Akasaka T 《Chemical communications (Cambridge, England)》2012,48(9):1290-1292
We describe the first example of scandium dimetallofullerenes, Sc(2)@C(3v)(8)-C(82), which has the same cage as the previously assigned scandium carbide cluster fullerene Sc(2)C(2)@C(3v)(8)-C(82) but they exhibit distinctly different electronic configurations and electronic behaviours, confirming the drastic influence of the internal C(2) unit. 相似文献
134.
Claudia Aparicio Libor Machala Zdenek Marusak 《Journal of Thermal Analysis and Calorimetry》2012,110(2):661-669
The thermal decomposition of Prussian blue (iron(III) hexacyanoferrate) under inert atmosphere of argon was monitored by thermal analysis from room temperature up to 1000?°C. X-ray powder diffraction and 57Fe M?ssbauer spectroscopy were the techniques used for phase identification before and after sample heating. The decomposition reaction is based on a successive release of cyanide groups from the Prussian blue structure. Three principal stages were observed including dehydration, change of crystal structure of Prussian blue, and its decomposition. At 400?°C, a monoclinic Prussian blue analogue was identified, while at higher temperatures the formation of various polymorphs of iron carbides was observed, including an orthorhombic Fe2C. Increase in the temperature above 700?°C induced decomposition of primarily formed Fe7C3 and Fe2C iron carbides into cementite, metallic iron, and graphite. The overall decomposition reaction can be expressed as follows: Fe4[Fe(CN)6]3·4H2O????4Fe?+?Fe3C?+?7C?+?5(CN)2?+?4N2?+?4H2O. 相似文献
135.
Feng L Rudolf M Wolfrum S Troeger A Slanina Z Akasaka T Nagase S Martín N Ameri T Brabec CJ Guldi DM 《Journal of the American Chemical Society》2012,134(29):12190-12197
The potential of Lu(3)N@C(80) and its analogues as electron acceptors in the areas of photovoltaics and artificial photosynthesis is tremendous. To this date, their electron-donating properties have never been explored, despite the facile oxidations that they reveal when compared to those of C(60). Herein, we report on the synthesis and physicochemical studies of a covalently linked Lu(3)N@C(80)-perylenebisimide (PDI) conjugate, in which PDI acts as the light harvester and the electron acceptor. Most important is the unambiguous evidence--in terms of spectroscopy and kinetics--that corroborates a photoinduced electron transfer evolving from the ground state of Lu(3)N@C(80) to the singlet excited state of PDI. In stark contrast, the photoreactivity of a C(60)-PDI conjugate is exclusively governed by a cascade of energy-transfer processes. Also, the electron-donating property of the Lu(3)N@C(80) moiety was confirmed through constructing and testing a bilayer heterojunction solar cell device with a PDI and Lu(3)N@C(80) derivative as electron acceptor and electron donor, respectively. In particular, a positive photovoltage of 0.46 V and a negative short circuit current density of 0.38 mA are observed with PDI/Ca as anode and ITO/Lu(3)N@C(80) as cathode. Although the devices were not optimized, the sign of the V(OC) and the flow direction of J(SC) clearly underline the unique oxidative role of Lu(3)N@C(80) within electron donor-acceptor conjugates toward the construction of novel optoelectronic devices. 相似文献
136.
Jiang L Aigret B De Borggraeve WM Spacil Z Ilag LL 《Analytical and bioanalytical chemistry》2012,403(6):1719-1730
Algal blooms are well-known sources of acute toxic agents that can be lethal to aquatic organisms. However, one such toxin, β-N-methylamino-L-alanine (BMAA) is also believed to cause amyotrophic lateral sclerosis, also known as Lou Gehrig's disease. The detection and identification of BMAA in natural samples were challenging until the recent introduction of reliable methods. However, the issue of potential interference from unknown isomers of BMAA present in samples has not yet been thoroughly investigated. Based on a systematic database search, we generated a list of all theoretical BMAA structural isomers, which was subsequently narrowed down to seven possible interfering compounds for further consideration. The seven possible candidates satisfied the requirements of chemical stability and also shared important structural domains with BMAA. Two of the candidates, 2,4-diaminobutyric acid (DAB) and N-(2-aminoethyl) glycine (AEG) have recently been studied in the context of BMAA. A further isomer, β-amino-N-methyl-alanine (BAMA), has to be considered because it can potentially yield the fragment ion, which is diagnostic for BMAA. Here, we report the synthesis and analysis of BAMA, together with AEG, DAB, and other isomers that are of interest in the separation and detection of BMAA in biological samples by using either high-performance liquid chromatography or ultra-high-performance liquid chromatography coupled with tandem mass spectrometry. We detected for the first time BAMA in blue mussel and oyster samples. This work extends the previously developed liquid chromatography-tandem mass spectrometry platform Spacil et al. (Analyst 135:127, 2010) to allow BMAA isomers to be distinguished, improving the detection and identification of this important amino acid. 相似文献
137.
Rui Gusmo Zdenek Sofer Martin Pumera 《Angewandte Chemie (International ed. in English)》2019,58(28):9326-9337
Owing to their unique physical and chemical properties, layered two‐dimensional (2D) materials have been established as the most significant topic in materials science for the current decade. This includes layers comprising mono‐element (graphene, phosphorene), di‐element (metal dichalcogenides), and even multi‐element. A distinctive class of 2D layered materials is the metal phosphorous trichalcogenides (MPCh3, Ch=S, Se), first synthesized in the late 1800s. Having an unusual intercalation behavior, MPCh3 were intensively studied in the 1970s for their magnetic properties and as secondary electrodes in lithium batteries, but fell from scrutiny until very recently, being 2D nanomaterials. Based on their synthesis and most significant properties, the present surge of reports related to water‐splitting catalysis and energy storage are discussed in detail. This Minireview is intended as a baseline for the anticipated new wave of researchers who aim to explore these 2D layered materials for their electrochemical energy applications. 相似文献
138.
Jiri Sturala Zdenek Sofer Martin Pumera 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(23):7631-7637
Materials with few layers have been subjected to extensive research for the last few decades owing to their remarkable properties as for example catalysts, optical and electrical devices, or sensors. The properties and electronic structure of these materials can be tailored by the introduction of substituents. In the case of more reactive species, the modification also can improve stability, which is also an important factor with respect to device fabrication. This review focuses on monoelemental layered materials of Group 15 elements (pnictogens) and in particular their modification, leading to better ambient stability and/or different properties by covalent and non‐covalent modifications. The future modification and application of pnictogens are outlined. 相似文献
139.
Inside Cover: Anticorrelation between Surface and Subsurface Point Defects and the Impact on the Redox Chemistry of TiO2(110) (ChemPhysChem 2/2015)
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140.