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The assessment of human health risks resulting from the presence of metabolites in groundwater and food residues has become an important element in pesticide authorisation. In this context, the evaluation of mutagenicity is of particular interest and a paradigm shift from exposure-triggered testing to in silico-based screening has been recommended in the European Food Safety Authority (EFSA) Guidance on the establishment of the residue definition for dietary risk assessment. In addition, it is proposed to apply in silico predictions when experimental mutagenicity testing is not possible due to a lack of sufficient quantities of the pesticide metabolite. This, combined with animal welfare and economic considerations, has led to a situation where an increasing number of in silico studies are submitted to regulatory authorities. Whilst there is extensive experience with in silico predictions for mutagenicity in the chemical and pharmaceutical industry, their suitability in pesticide regulation is still insufficiently considered. Therefore, we herein discuss critical issues that need to be resolved to successfully implement (Quantitative) Structure-Activity Relationship ((Q)SAR) as an accepted tool in pesticide regulation. For illustration purposes, the results of a pilot study are included. The presented study highlights a need for further improvement regarding the predictivity and applicability domain of (Q)SAR systems for pesticides and their metabolites, but also raises other questions such as model selection, establishment of acceptance criteria, harmonised approaches to the combination of model outputs into overall conclusions, adequate reporting and data sharing. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Der Begriff Aerogel beschreibt im Wesentlichen eine besondere geometrische Struktur der Materie, die materialunabhangig ist und keinem speziellen Syntheseverfahren unterliegt. Grundsatzlich konnen daher Aerogele aus unzahligen Materialien bestehen, wodurch die Anwendungsmoglichkeiten nahezu unbegrenzt sind. Dasselbe trifft auf Nanopartikel zu. Diese werden ebenso durch ihre geometrischen Eigenschaften definiert. In den letzten Jahrzehnten standen daher nanoskalige Materialien im Fokus der Forschung, und es entwickelten sich mogliche Anwendungen in vielen naturwissenschaftlichen Bereichen. Heute ist eine Vielzahl an Metall-, Halbleiter-, Oxid- und anderen Nanopartikeln durch kolloidale Synthesen zuganglich. Dennoch ist es fur eine Anwendung oft notwendig, dass diese Materialien zuvor in makroskopische Strukturen angeordnet werden. Dieser Aufsatz gibt eine ausfuhrliche Ubersicht uber die Entwicklung, die die Welt der kolloidalen Nanopartikel und der Aerogele miteinander vereint. Ermoglicht wurde dies durch die kontrollierte Destabilisierung der vorab gebildeten Nanopartikel, die zu einer Anordnung der Nanopartikel zu einem dreidimensionalen, makroskopischen Netzwerk fuhrt. Dieses revolutionare Konzept verleiht die Moglichkeit, prazise kontrollierte Nanopartikel als Grundbausteine fur makroskopische, porose Strukturen mit einstellbaren Eigenschaften zu nutzen.

Multimetallic aerogels have emerged as promising unsupported and high-surface-area metal materials for different applications in heterogeneous catalysis and electrochemistry, which are fabricated using a gelation process characterized by the controlled aggregation of metallic nanoparticles to form a macroscopic network structure in aqueous solution. However, the achievement of the structural homogeneity of the multimetallic aerogels in terms of the diameter of the nanochains and the chemical composition at the nano- and the macro-scale is still a great challenge. In this paper, we investigated two Pd-Pt aerogels prepared by the two-step gelation method. The structural homogeneity and chemical distribution of both metals inside the aerogels were analyzed by using high-resolution (scanning) transmission microscopy, energy-dispersive X-ray spectroscopy, extended X-ray absorption fine structure spectroscopy and cyclic voltammetry. The Pd-Pt aerogels show the presence of Pd/Pt-rich domains inside the long-range framework. It is evident that the initial monometallic features dominate over alloying during the gelation process. Although the same synthetic approach for Pd-Pt aerogels with different atomic ratios was used, we observed that the sizes of these monometallic domains varied strongly between the Pd-rich and Pt-rich aerogels. The presence of such metal clusters influenced the electrochemical robustness of the Pd-Pt aerogels dramatically. Electrochemical durability investigations revealed that the aerogels with a high content of Pd are less stable because of the gradual dissolution of the less noble metal particularly inside the Pd-rich domains. A chemical and structural homogeneity might improve the lifetime of the Pd-Pt aerogels under electrochemical conditions. In this work, we provide a better understanding of the structure and chemical distribution of the bimetallic aerogel framework prepared by the two-step gelation process.

One plausible approach to endow aerogels with specific properties while preserving their other attributes is to fine-tune the building blocks. However, the preparation of metallic aerogels with designated properties, for example catalytically beneficial morphologies and transition-metal doping, still remains a challenge. Here, we report on the first aerogel electrocatalyst composed entirely of alloyed PdNi hollow nanospheres (HNSs) with controllable chemical composition and shell thickness. The combination of transition-metal doping, hollow building blocks, and the three-dimensional network structure make the PdNi HNS aerogels promising electrocatalysts for ethanol oxidation. The mass activity of the Pd83 Ni17 HNS aerogel is 5.6-fold higher than that of the commercial Pd/C catalyst. This work expands the exploitation of the electrocatalysis properties of aerogels through the morphology and composition control of its building blocks.

Eine gezielte Verbesserung der Baueinheiten ist eine naheliegende Herangehensweise, um Aerogele mit herausragenden Eigenschaften zu versehen und gleichzeitig ihre Vorzuge zu erhalten. Bestimmte Eigenschaften, wie die Optimierung der Morphologie fur katalytische Anwendungen oder die Ubergangsmetalldotierung in metallischen Aerogelen, sind jedoch nach wie vor schwer zu realisieren. In diesem Zusammenhang prasentieren wir hier erstmalig elektrokatalytisch aktive Aerogele, welche sich vollstandig aus legierten PdNi-Hohlnanospharen (HNS) aufbauen und deren chemische Zusammensetzung und Schalendicke gezielt eingestellt werden kann. Die Kombination von Ubergangsmetalldotierung mit hohlen Baueinheiten in einem dreidimensionalen Netzwerk machen PdNi-HNS-Aerogele zu vielversprechenden Elektrokatalysatoren fur die Ethanoloxidation. Gegenuber dem kommerziellen Pd/C-Katalysator zeigt das Pd83Ni17-HNS-Aerogel eine 5.6-fach hohere Massenaktivitat. Durch diese Arbeit wird die Nutzbarkeit von metallischen Aerogelen in der Elektrokatalyse erweitert, indem die Morphologie und Zusammensetzung der Baueinheiten gezielt kontrolliert werden.

In this study, we introduce the first membraneless glucose/O2 biofuel cell using Pd-based aerogels as electrode materials. The bioanode was fabricated with a coimmobilized mediator and glucose oxidase for the oxidation of glucose, in which ferrocenecarboxylic acid was integrated into a three-dimensional porous beta-cyclodextrin-modified Pd aerogel to mediate the bioelectrocatalytic reaction. Bilirubin oxidase and Pd-Pt alloy aerogel were confined to an electrode surface, which realized the direct bioelectrocatalytic function for the reduction of O2 to H2 O with a synergetic effect at the biocathode. By employing these two bioelectrodes, the assembled glucose/O2 biofuel cell showed a maximum power output of 20 μW cm(-2) at 0.25 V.

Mixed metal–semiconductor nanocrystal aerogels are fabricated, which are light-emitting and highly porous macroscopic monoliths. Thiol-stabilized CdTe and Au nanoparticles from aqueous synthesis act as building blocks for the hybrid material. The Au colloids undergo a surface-modifi cation to enhance the particle stability and achieve thiol functionalities. A photochemical treatment is applied for the gelation process which is found to be reversible by subsequent addition of thiol molecules. Via supercritical drying aerogels are formed. The variation of the initial CdTe to Au nanoparticle ratio permits a facile tuning of the content and the properties of the resulting aerogels. The obtained structures were characterized by means of optical spectroscopy, electron microscopy, elemental analysis, and nitrogen physisorption.