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Based on classical contagion models we introduce an artificial cyber lab: the digital twin of a complex cyber system in which possible cyber resilience measures may be implemented and tested. Using the lab, in numerical case studies, we identify two classes of measures to control systemic cyber risks: security‐ and topology‐based interventions. We discuss the implications of our findings on selected real‐world cybersecurity measures currently applied in the insurance and regulation practice or under discussion for future cyber risk control. To this end, we provide a brief overview of the current cybersecurity regulation and emphasize the role of insurance companies as private regulators. Moreover, from an insurance point of view, we provide first attempts to design systemic cyber risk obligations and to measure the systemic risk contribution of individual policyholders. [ABSTRACT FROM AUTHOR]

Partial ligand substitution at the iron pentacarbonyl radical cation generates novel half‐sandwich complexes of the type [Fe(η6‐arene)(CO)2]⋅+ (arene=1,3,5‐tri‐tert‐butylbenzene, 1,3,5‐trimethylbenzene, benzene and fluorobenzene). Of those, the bulkier 1,3,5‐tri‐tert‐butylbenzene (mes*) derivative [Fe(mes*)(CO)2]⋅+ was fully characterized by XRD analysis, IR, NMR, cw‐EPR, Mössbauer spectroscopy and cyclic voltammetry as the [Al(ORF)4]− (RF=C(CF3)3) salt. Chemical electronation, i. e. the single electron reduction, with decamethylferrocene generates neutral [Fe(mes*)(CO)2], whereas further deelectronation under CO‐pressure leads to a dicationic three‐legged [Fe(mes*)(CO)3]2+ salt with [Al(ORF)4]− counterion. The full substitution of the carbonyl ligands in [Fe(CO)5]⋅+[Al(ORF)4]− mainly resulted in disproportionation reactions, giving solid Fe(0) and the dicationic bis‐arene salts [Fe(η6‐arene)2]2+([Al(ORF)4]−)2 (arene=1,3,5‐trimethylbenzene, benzene and fluorobenzene). Only by employing the very large fluoride bridged anion [F‐{Al(ORF)3}2]−, it was possible to isolate an open shell bis‐arene cation salt [Fe(C6H6)2]⋅+[F‐{Al(ORF)3}2]−. The highly reactive cation was characterized by XRD analysis, cw‐EPR, Mössbauer spectroscopy and cyclic voltammetry. The disproportionation of [Fe(C6H6)2]⋅+ salts to give solid Fe(0) and [Fe(C6H6)2]2+ salts was analyzed by a suitable cycle, revealing that the thermodynamic driving force for the disproportionation is a function of the size of the anion used and the polarity of the solvent. [ABSTRACT FROM AUTHOR]

Understanding electron and ion dynamics is an important task for improving modern energy materials, such as photovoltaic perovskites. These materials usually have delicate nano‐ and microstructures that influence the device parameters. To resolve detailed structure–function relationships on the relevant micro‐ and nanometer length scales, the current macroscopic and microscopic measurement techniques are often not sufficient. Here, nanoscale surface photovoltage spectroscopy (nano‐SPV) and nanoscale ideality factor mapping (nano‐IFM) via time‐resolved Kelvin probe force microscopy are introduced. These methods can map nanoscale variations in charge carrier recombination, ion migration, and defects. To show the potential of nano‐SPV and nano‐IFM, these methods are applied to perovskite samples with different morphologies. The results clearly show an improved uniformity of the SPV and SPV decay distribution within the perovskite films upon passivation and increasing the grain size. Nevertheless, nano‐SPV and nano‐IFM can still detect local variations in the defect density on these optimized samples, guiding the way for further optimization. [ABSTRACT FROM AUTHOR]

Deazaflavins are important analogues of the naturally occurring flavins: riboflavin, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD). The use of 5‐deazaflavin as a replacement coenzyme in a number of flavoproteins has proven particularly valuable in unraveling and manipulating their reaction mechanisms. It was frequently reported that one‐electron‐transfer reactions in flavoproteins are impeded with 5‐deazaflavin as the cofactor. Based on these findings, it was concluded that the 5‐deazaflavin radical is significantly less stable compared to the respective flavin semiquinone and quickly re‐oxidizes or undergoes disproportionation. The long‐standing paradigm of 5‐deazaflavin being solely a two‐electron/hydride acceptor/donor—"a nicotinamide in flavin clothing"—needs to be re‐evaluated now with the indirect observation of a one‐electron‐reduced (paramagnetic) species using photochemically induced dynamic nuclear polarization (photo‐CIDNP) 1H nuclear magnetic resonance (NMR) under biologically relevant conditions. [ABSTRACT FROM AUTHOR]

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The unsubstituted acenium radical cations (ARCs) are extremely sensitive and were hitherto only studied in situ, i. e. in the gas phase, as dilute solutions in strong acids or by matrix isolation spectroscopy at about 10 K. In this study, room temperature stable ARC salts with the weakly coordinating anion [F{Al(ORF)3}2]− (ORF=−OC(CF3)3) supported by the weakly coordinating solvent 1,2,3,4‐tetrafluorobenzene (TFB) were prepared and structurally, electrochemically and spectroscopically characterized. Reaction of the neutral acenes with Ag+[F{Al(ORF)3}2]− led, non‐innocent,[54] to intermediate [Ag2(acene)2]2+ complexes, which decompose over time to Ag0 and the corresponding (impure) ARC salts. By contrast, direct deelectronation with the recently developed innocent[54] deelectronator radical cation salt [anthraceneHal]+⋅[F{Al(ORF)3}2]− led to phase‐pure products [acene]+⋅[F{Al(ORF)3}2]− (anthraceneHal=9,10‐dichlorooctafluoroanthracene; acene=anthra‐, tetra‐, pentacene). For the first time, a homogenous set of spectroscopic data on analytically pure ARC salts was obtained. In addition, cyclovoltammetric measurements of the acenes connected the potentials in solution with those in the gas‐phase. Hence, the data complement the existing isolated gas‐phase, strong acid or matrix isolation studies. A first entry to follow‐up chemistry of the acenium radical cations as ligand forming oxidizers was demonstrated by reaction with 1/2 ${{ 1/2 }}$ Co2(CO)8 giving [Co(anthracene)(CO)2]+. [ABSTRACT FROM AUTHOR]

Protection of creditors is a key objective of financial regulation. Where the protection needs are high, that is, in banking and insurance, regulatory solvency requirements are an instrument to prevent that creditors incur losses on their claims. The current regulatory requirements based on value at risk (V@R) and average value at risk (AV@R) limit the probability of default of financial institutions, but they fail to control the size of recovery on creditors' claims in the case of default. We resolve this failure by developing a novel risk measure, recovery V@R. Our conceptual approach is flexible and allows the construction of general recovery risk measures for various risk management purposes. We provide detailed case studies and applications. We show that recovery risk measures can be used for performance‐based management of business divisions of firms and discuss how to calibrate recovery risk measures to historical regulatory standards. Finally, we analyze how recovery risk measures react to the joint distributions of assets and liabilities on firms' balance sheets and compare the corresponding capital requirements with the current regulatory benchmarks based on V@R and AV@R. [ABSTRACT FROM AUTHOR]

The synthesis of imines denotes a cornerstone in organic chemistry. The use of alcohols as renewable substituents for carbonyl-functionality represents an attractive opportunity. Consequently, carbonyl moieties can be in situ generated from alcohols upon transition-metal catalysis under inert atmosphere. Alternatively, bases can be utilized under aerobic conditions. In this context, we report the synthesis of imines from benzyl alcohols and anilines, promoted by KOtBu under aerobic conditions at room temperature, in the absence of any transition-metal catalyst. A detailed investigation of the radical mechanism of the underlying reaction is presented. This reveals a complex reaction network fully supporting the experimental findings. [ABSTRACT FROM AUTHOR]

This study introduces a new chemical method for controlling the strain in methylammonium lead iodide (MAPbI3) perovskite crystals by varying the ratio of Pb(Ac)2 and PbCl2 in the precursor solution. To observe the effect on crystal strain, a combination of piezoresponse force microscopy (PFM) and X‐ray diffraction (XRD) is used. The PFM images show an increase in the average size of ferroelastic twin domains upon increasing the PbCl2 content, indicating an increase in crystal strain. The XRD spectra support this observation with strong crystal twinning features that appear in the spectra. This behavior is caused by a strain gradient during the crystallization due to different evaporation rates of methylammonium acetate and methylammonium chloride as revealed by time‐of‐flight secondary ion mass spectroscopy and grazing incidince X‐ray diffraction measurements. Additional time‐resolved photoluminescence shows an increased carrier lifetime in the MAPbI3 films prepared with higher PbCl2 content, suggesting a decreased trap density in films with larger twin domain structures. The results demonstrate the potential of chemical strain engineering as a simple method for controlling strain‐related effects in lead halide perovskites. [ABSTRACT FROM AUTHOR]

A MnI‐catalyzed hydroboration of terminal alkenes and a 1,2‐diboration of terminal alkynes with pinacolborane (HBPin) is described. For alkenes, anti‐Markovnikov hydroboration takes place; for alkynes the reaction proceeds with excellent trans‐1,2‐selectivity. The most active pre‐catalyst is bench‐stable alkyl bisphosphine MnI complex fac‐[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn–alkyl bond to yield an acyl intermediate, which undergoes B−H bond cleavage of HBPin (for alkenes) and rapid C−H bond cleavage (for alkynes), forming the active MnI boryl and acetylide catalysts [Mn(dippe)(CO)2(BPin)] and [Mn(dippe)(CO)2(C≡CR)], respectively. A broad variety of aromatic and aliphatic alkenes and alkynes was efficiently and selectively borylated. Mechanistic insights are provided based on experimental data and DFT calculations revealing that an acceptorless reaction is operating involving dihydrogen release. [ABSTRACT FROM AUTHOR]

Antibodies play an important role in host defense against microorganisms. Besides direct microbicidal activities, antibodies can also provide indirect protection via crosstalk to constituents of the adaptive immune system. Similar to many human chronic viral infections, persistence of Lymphocytic choriomeningitis virus (LCMV) is associated with compromised T‐ and B‐cell responses. The administration of virus‐specific non‐neutralizing antibodies (nnAbs) prior to LCMV infection protects against the establishment of chronic infection. Here, we show that LCMV‐specific nnAbs bind preferentially Ly6Chi inflammatory monocytes (IMs), promote their infection in an Fc‐receptor independent way, and support acquisition of APC properties. By constituting additional T‐cell priming opportunities, IMs promote early activation of virus‐specific CD8 T cells, eventually tipping the balance between T‐cell exhaustion and effector cell differentiation, preventing establishment of viral persistence without causing lethal immunopathology. These results document a beneficial role of IMs in avoiding T‐cell exhaustion and an Fc‐receptor independent protective mechanism provided by LCMV‐specific nnAbs against the establishment of chronic infection. [ABSTRACT FROM AUTHOR]

Copyright of Nachrichten aus der Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The development of nucleoside triphosphate prodrugs is one option to apply nucleoside reverse transcriptase inhibitors. Herein, we report the synthesis and evaluation of d4TTP analogues, in which the γ‐phosphate was modified covalently by lipophilic alkyl residues, and acyloxybenzyl prodrugs of these γ‐alkyl‐modified d4TTPs, with the aim of delivering of γ‐alkyl‐d4TTP into cells. Selective formation of γ‐alkyl‐d4TTP was proven with esterase and in CD4+‐cell extracts. In contrast to d4TTP, γ‐alkyl‐d4TTPs proved highly stable against dephosphorylation. Primer extension assays with HIV reverse transcriptase (RT) and DNA‐polymerases α, β or γ showed that γ‐alkyl‐d4TTPs were substrates for HIV‐RT only. In antiviral assays, compounds were highly potent inhibitors of HIV‐1 and HIV‐2 also in thymidine‐kinase‐deficient T‐cell cultures (CEM/TK−). Thus, the intracellular delivery of such γ‐alkyl‐nucleoside triphosphates may potentially lead to nucleoside triphosphates with a higher selectivity towards the viral polymerase that can act in virus‐infected cells. [ABSTRACT FROM AUTHOR]

Arylazopyrazoles are an emerging class of photoswitches with redshifted switching wavelength, high photostationary states, long thermal half‐lives and facile synthetic access. Understanding pathways for a simple modulation of the thermal half‐lives, while keeping other parameters of interest constant, is an important aspect for out‐of‐equilibrium systems design and applications. Here, it is demonstrated that the thermal half‐life of a water‐soluble PEG‐tethered arylazo‐bis(o‐methylated)pyrazole (AAP) can be tuned by more than five orders of magnitude using simple pH adjustment, which is beyond the tunability of azobenzenes. The mechanism of thermal relaxation is investigated by thorough spectroscopic analyses and density functional theory (DFT) calculations. Finally, the concepts of a tunable half‐life are transferred from the molecular scale to the material scale. Based on the photochromic characteristics of E‐ and Z‐AAP, transient information storage is showcased in form of light‐written patterns inside films cast from different pH, which in turn leads to different times of storage. With respect to prospective precisely tunable materials and time‐programmed out‐of‐equilibrium systems, an externally tunable half‐life is likely advantageous over changing the entire system by the replacement of the photoswitch. [ABSTRACT FROM AUTHOR]

We prepared conceptually novel, fully rigid, spiro compact electron donor (Rhodamine B, lactam form, RB)/acceptor (naphthalimide; NI) orthogonal dyad to attain the long‐lived triplet charge‐transfer (3CT) state, based on the electron spin control using spin‐orbit charge transfer intersystem crossing (SOCT‐ISC). Transient absorption (TA) spectra indicate the first charge separation (CS) takes place within 2.5 ps, subsequent SOCT‐ISC takes 8 ns to produce the 3NI* state. Then the slow secondary CS (125 ns) gives the long‐lived 3CT state (0.94 μs in deaerated n‐hexane) with high energy level (ca. 2.12 eV). The cascade photophysical processes of the dyad upon photoexcitation are summarized as 1NI*→1CT→3NI*→3CT. With time‐resolved electron paramagnetic resonance (TREPR) spectra, an EEEAAA electron‐spin polarization pattern was observed for the naphthalimide‐localized triplet state. Our spiro compact dyad structure and the electron spin‐control approach is different to previous methods for which invoking transition‐metal coordination or chromophores with intrinsic ISC ability is mandatory. [ABSTRACT FROM AUTHOR]

The perfluorinated dihydrophenazine derivative (perfluoro‐5,10‐bis(perfluorophenyl)‐5,10‐dihydrophenazine) ("phenazineF") can be easily transformed to a stable and weighable radical cation salt by deelectronation (i.e. oxidation) with Ag[Al(ORF)4]/ Br2 mixtures (RF=C(CF3)3). As an innocent deelectronator it has a strong and fully reversible half‐wave potential versus Fc+/Fc in the coordinating solvent MeCN (E°′=1.21 V), but also in almost non‐coordinating oDFB (=1,2‐F2C6H4; E°′=1.29 V). It allows for the deelectronation of [FeIIICp*2]+ to [FeIV(CO)Cp*2]2+ and [FeIV(CN‐tBu)Cp*2]2+ in common laboratory solvents and is compatible with good σ‐donor ligands, such as L=trispyrazolylmethane, to generate novel [M(L)x]n+ complex salts from the respective elemental metals. [ABSTRACT FROM AUTHOR]

An efficient additive‐free manganese‐catalyzed hydrogenation of nitriles to primary amines with molecular hydrogen is described. The pre‐catalyst, a well‐defined bench‐stable alkyl bisphosphine Mn(I) complex fac‐[Mn(dpre)(CO)3(CH3)] (dpre=1,2‐bis(di‐n‐propylphosphino)ethane), undergoes CO migratory insertion into the manganese‐alkyl bond to form acyl complexes which upon hydrogenolysis yields the active coordinatively unsaturated Mn(I) hydride catalyst [Mn(dpre)(CO)2(H)]. A range of aromatic and aliphatic nitriles were efficiently and selectively converted into primary amines in good to excellent yields. The hydrogenation of nitriles proceeds at 100 °C with a catalyst loading of 2 mol % and a hydrogen pressure of 50 bar. Mechanistic insights are provided by means of DFT calculations. [ABSTRACT FROM AUTHOR]

Background & Aims: Ablation plays an important role in the treatment of hepatocellular carcinoma. Because image‐guided navigation technology has recently entered the clinical setting, we aimed to analyse its safety, therapeutic and procedural efficiency. Methods: Retrospective analysis of patients treated with stereotactic image‐guided microwave ablation (SMWA) between January 2015 and December 2017. Interventions were performed using computertomography‐guidance with needle trajectory, ablation planning and automatic single‐marker patient registration. Needle placement and ablation coverage was controlled by image fusion under general anaesthesia with jet‐ventilation. Results: In total 174 ablations were performed in 88 patients during 119 interventions. Mean age was 66 (46‐84) years, 74 (84.1%) were men and 74% were Child Pugh Class A. Median tumour size was 16 (4‐45) mm, 62.2% were BCLC A. Median lateral and longitudinal error of needle placement were 3.2 (0.2‐14.1) and 1.6 (0‐15.8) mm. Median one tumour (1‐4) was ablated per session. One patient developed a Dindo IIIb (0.8%) complication, six minor complications. After re‐ablation of 12 lesions, an efficacy rate of 96.3% was achieved. Local tumour progression was 6.3% (11/174). Close proximity to major vessels was significantly correlated with local tumour progression (P < .05). Median overall follow‐up was 17.5 months after intervention and 24 months after initial diagnosis. BCLC stage, child class and previous treatment were significantly correlated with overall survival (P < .05). Conclusion: Stereotactic image‐guided microwave ablation is a safe and efficient treatment for HCC offering a curative treatment approach in general and in particular for lesions not detectable on conventional imaging or untreatable because of difficult anatomic locations. See Editorial on Page 1798 [ABSTRACT FROM AUTHOR]

Protective immunity against intracellular pathogens, including bacteria, usually relies on cellular immunity. However, antibodies are also implicated in mediating protection against intracellular bacteria. In case of airway infection with Legionella pneumophila (Lpn), the causative agent of Legionnaires' disease, pre‐existing Lpn‐specific antibodies were shown to afford protection within two days of infection. Here we dissected the early kinetics of Ab‐mediated protection against airway Lpn infection and observed two kinetically and mechanistically distinct phases of protection by passively administered antibodies. Within the first hour of infection, Lpn‐opsonizing antibodies provided almost 10‐fold protection in an antibody Fc‐dependent, but FcR‐independent manner. Later on, by two days post infection, Lpn‐specific Ab‐mediated protection strictly involved FcγR, Syk kinase activity in alveolar macrophages and induction of reactive oxygen species (ROS). The findings presented here contribute to the understanding of the mechanisms of Ab‐mediated control of Lpn infection in actively or passively immunized individuals. [ABSTRACT FROM AUTHOR]

The NiI salt [Ni(cod)2]+[Al(ORF)4]– {RF = C(CF3)3} is the starting material for ligand exchange reactions with arenes (benzene, mesitylene and hexamethylbenzene) yielding cationic and purely organometallic 19 valence electron [Ni(cod)(arene)]+ complex salts. The reactions are accompanied by fast solution color changes from yellow to intensely green. Single crystal X‐ray structure analysis, EPR, UV/Vis and IR‐spectroscopic investigations confirm the formation of [Ni(cod)(C6Me6)][Al(ORF)4] (2) as well as [Ni(cod)(mes)][Al(ORF)4] (3, mes = mesitylene) with η6‐coordinated arenes and bidentate cod ligands. The reaction with benzene is plausible but remains less characterized. The energetics of these reactions were used to evaluate diverse DFT methods. 16 functionals with and without D3(BJ) dispersion correction failed to describe the reaction energetics correctly. However, correcting the basic reaction energies with a CCSD(T)/TZ→QZ approach and using further isodesmic reactions with inclusion of COSMO‐RS solvation gave reaction energetics in best agreement with all experimental observations. [ABSTRACT FROM AUTHOR]

A biphasic process for the hydrogenation of aldehydes was developed using a well‐defined iron (II) PNP pincer complex as model system to investigate the performance of various ionic liquids. A number of suitable hydrophobic ionic liquids based on the N(Tf)2− anion were identified, allowing to immobilize the iron (II) catalyst in the ionic liquid layer and to facilitate the separation of the desired alcohols. Further studies showed that targeted Brønsted basic ionic liquids can eliminate the need of an external base to activate the catalyst. Biphasic catalysis: A biphasic process for the hydrogenation of aldehydes was developed using a well‐defined iron (II) PNP pincer complex in various ionic liquids as reaction media. [ABSTRACT FROM AUTHOR]

Here we report on a paediatric case from Germany where TB focused abdominal ultrasound during the diagnostic TB work-up was the determining diagnostic tool to establish a timely diagnosis of active TB. In our case, the additional diagnostic value of TB focused abdominal ultrasound was decisive in establishing the diagnosis of active TB at the time of presentation and hence several weeks before cultures confirmed the diagnosis. Irrespective of TB endemicity children have a higher risk for extra-thoracic TB even in the absence of HIV-infection and may therefore benefit from abdominal ultrasound during TB work-up. In summary, available evidence and our case report suggest that the diagnostic utility of (TB focused) ultrasound as a standard diagnostic examination during paediatric and adult TB work-up should also be investigated in settings with an overall low TB burden. [Extracted from the article]

Abstract: The development of energy‐conversion devices using water movement has actively progressed. Ionovoltaic devices, which are driven by ion dynamics, show ion specificity by which different ions with identical charges show different output performance. However, the ion specificity remains poorly understood because the influence of the ion species on generated electric signals is not elucidated. The ion specificity in electric signals induced by flowing water droplet was investigated in terms of its relationship with the potential profile across the solid–liquid interface. [ABSTRACT FROM AUTHOR]

To provide a better understanding of the recently published pure metalorganic NiI species, [Ni(cod)2][Al(ORF)4] (1) [cod = 1,5- cyclooctadiene, RF = C(CF3)3], further characterizations were performed and analyzed. Thus, the solvation of 1 in THF was examined by EPR, surprisingly disclosing the initiation of a disproportionation reaction to [NiII(THF)6][Al(ORF)4]2 (3) and Ni0. Further studies con- cerning the ability of 1 to activate small molecules exhibit the formation of a remarkable [Ni3S2(cod)3]2+ cluster (5) in an oxidation reaction with S8, while EPR measurements of the resulting product in a reaction with oxygen indicate a possible coordination of O2. Single crystal X-ray structures as well as spectroscopic analyses of 3 and 5 are described. [ABSTRACT FROM AUTHOR]

The recently published purely metallo-organic NiI salt [Ni(cod)2][Al(ORF)4] (1, cod=1,5-cyclooctadiene, RF= C(CF3)3) provides a starting point for a new synthesis strategy leading to NiI phosphine complexes, replacing cod ligands by phosphines. Clearly visible colour changes indicate reactions within minutes, while quantum chemical calculations (PBE0-D3(BJ)/def2-TZVPP) approve exergonic reaction enthalpies in all performed ligand exchange reactions. Hence, [Ni(dppp)2][Al(ORF)4] (2, dppp=1,3-bis(diphenylphosphino) propane), [Ni(dppe)2][Al(ORF)4] (3, dppe=1,3-bis(diphenyl- phosphino)ethane), three-coordinate [Ni(PPh3)3] [Al(ORF)4] (4) and a remarkable two-coordinate NiI phosphine complex [Ni(PtBu3)2][Al(ORF)4] (5) were characterised by single crystal X-ray structure analysis. EPR studies were performed, confirming a nickel d9 -configuration in complexes 2, 4 and 5. This result is supported by additional magnetization measurements of 4 and 5. Further investigations by cyclic voltammetry indicate relatively high oxidation potentials for these NiI compounds between 0.7 and 1.7 V versus Fc/Fc+. Screening reactions with O2 and CO gave first insights on the reaction behaviour of the NiI phosphine complexes towards small molecules with formation of mixed phosphine- CO-NiI complexes and oxidation processes yielding new NiI and/or NiII derivatives. Moreover, 4 reacted with CH2Cl2 at RT to give a dimeric NiII ylide complex (4c). As CH2Cl2 is a rather stable alkyl halide with relatively high C@Cl bond energies, 4 appears to be a suitable reagent for more general C@Cl bond activation reactions. [ABSTRACT FROM AUTHOR]

Here, this study reports a novel single-step preparation of graphene functionalized by redox-active nitroxyl radicals, a promising electrode material, without the requirement of graphite oxidation. Key feature of this concept is the Diels-Alder [4+2] cycloaddition of dispersed graphene (DG), which has been obtained by shear-induced solution exfoliation of graphite and functionalized maleimides as dienophiles. The redox-active organic radical 2,2,6,6,-tetramethylpiperdinyl-1-oxyl (TEMPO) is covalently attached by cycloaddition of DG with either N-(1-oxyl-2,2,6,6,-tetramethyl-4-piperidinyl)-maleimide (TEMPO-MI), or N-(2,2,6,6-tetramethyl-piperidinyl)-maleimide (TEMP-MI), and subsequent oxidation. Successful product formation could be confirmed by high field Electron Paramagnetic Resonance (EPR) spectroscopy. Temperature-dependent reaction monitoring by time-resolved EPR in conjunction with Raman spectroscopy and elemental analysis results in an optimum cycloaddition temperature of 130 °C, at which 2.2 wt% TEMPO-MI has been incorporated. However, owing to the limited thermal stability of TEMPO-MI at temperatures above 100 °C, as again verified by EPR spectroscopy, the route via TEMP-MI and subsequent oxidation is favored. Cyclovoltammetric evaluation of TEMPO-functionalized graphene shows a reversible redox potential of +0.65 V as measured against Ag/AgCl, similar to that of TEMPO in solution. Hence, organic radical functionalized graphene derived by cycloaddition shows great potential for an easy production of electrodes that aim toward applications in organic energy storage devices. [ABSTRACT FROM AUTHOR]

Light-generated short-lived radial pairs have been suggested to play pivotal roles in cryptochromes and photolyases. Cryptochromes are very probably involved in magnetic compass sensing in migratory birds and the magnetic-field-dependent behavior of insects. We examined photo-generated transient states in the cryptochrome of Drosophila melanogaster and in the structurally related DNA-repair enzyme Escherichia coli DNA photolyase. Using pulsed EPR spectroscopy, the exchange and dipolar contributions to the electron spin-spin interaction were determined in a straightforward and direct way. With these parameters, radical-pair partners may be identified and the magnetoreceptor efficiency of cryptochromes can be evaluated. We present compelling evidence for an extended electron-transfer cascade in the Drosophila cryptochrome, and identified W394 as a key residue for flavin photoreduction and formation of a spin-correlated radical pair with a sufficient lifetime for high-sensitivity magnetic-field sensing. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

5′-deoxyadenosyl radicals have been proposed as the first common intermediate in the molecular reaction mechanism of the family of radical S-adenosyl -l-methionine (SAM) enzymes. However, this radical species has not yet been directly observed in a catalytically active enzyme environment. In a reduced and SAM-containing C140A mutant of the spore photoproduct lyase from Geobacillus thermodenitrificans, a mutant with altered catalytic activity, we were able to identify an organic radical with pronounced hyperfine structure using electron paramagnetic resonance spectroscopy. Guided by quantum-chemical computations at the density functional theory level of theory, this radical could be tentatively assigned to a deoxyadenosyl radical, which provides first experimental evidence for this intermediate in the reaction mechanism of radical SAM enzymes. [ABSTRACT FROM AUTHOR]

This work characterizes the properties of deposited plasma polymer that has been generated using three different low-pressure, low-temperature plasma modes: magnetron-enhanced audio frequency (15 kHz), magnetron-enhanced radio frequency (13.56 MHz), and radio frequency (13.56 MHz). A correlation between the applied plasma modes, the concentration of generated radicals in the deposited nanofilms, and the radical decay kinetics was found and is discussed. In addition, the role of the plasma driving frequency with respect to the properties of the films, in particular their density and their barrier properties, has been elucidated. [ABSTRACT FROM AUTHOR]

Cu- and V-doped BNKT10-based piezoelectric ceramics with up to 0.5 at.% dopant concentration were synthesized and displayed more homogeneous grain growth compared to undoped BNKT10 ceramics. The defect chemistry and defect structure, studied by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR), indicate a slightly rhombic electronic environment with major unidirectional octahedral distortion of the local environment of Cu. The solubility limit of Cu2+ in this material system is lower than 0.05 at.% Cu; above this limit, a Cu segregation at the grain boundaries is prevalent, unlike in PZT and KNN. Here, V was shown to be incorporated into the perovskite lattice and possess oxidation states of +4 and +5, acting both as isovalent and donor dopant, predominantly compensated by A-site vacancies. A trend toward higher ceramic densities, higher maximum polarization, and higher remanent polarization with increasing Cu concentration was observed. A maximum mechanical coupling factor could be obtained in the case of doping with 0.4 at.% V and 0.1 at.% Cu with a planar coupling of 0.19 and a thickness coupling factor of 0.56. [ABSTRACT FROM AUTHOR]

The straightforward synthesis of the cationic, purely organometallic NiI salt [Ni(cod)2]+[Al(ORF)4]- was realized through a reaction between [Ni(cod)2] and Ag[Al(ORF)4] (cod=1,5-cyclooctadiene). Crystal-structure analysis and EPR, XANES, and cyclic voltammetry studies confirmed the presence of a homoleptic NiI olefin complex. Weak interactions between the metal center, the ligands, and the anion provide a good starting material for further cationic NiI complexes. [ABSTRACT FROM AUTHOR]

Blue light receptors using FAD ( BLUFs) facilitate blue light-induced signal transduction via light-induced rearrangement of hydrogen bonds between the flavin chromophore and a conserved glutamine side chain. Here, we investigated the photochemistry of the BLUF domain Slr1694 from Synechocystis sp. in which the glutamine side chain was removed. Without the glutamine, no red-shifted signaling state is formed, but light-induced proton-coupled electron transfer between protein and flavin takes place similarly as for the wild-type protein. However, the lifetime of the neutral flavin semiquinone-tyrosyl radical pair is greatly prolonged from < 100 ps to several nanoseconds, which indicates that the formation of radical intermediates drives the hydrogen bond rearrangement in BLUF photoactivation. Moreover, glutamine plays a central role in the molecular organization of the hydrogen bond network in the flavin-binding pocket, as its removal enhances electron transfer from tyrosine to the excited flavin, and enables competing electron transfer from a nearby tryptophan. [ABSTRACT FROM AUTHOR]

Drosophila melanogaster cryptochrome is one of the model proteins for animal blue-light photoreceptors. Using time-resolved and steady-state optical spectroscopy, we studied the mechanism of light-induced radical-pair formation and decay, and the photoreduction of the FAD cofactor. Exact kinetics on a microsecond to minutes timescale could be extracted for the wild-type protein using global analysis. The wild-type exhibits a fast photoreduction reaction from the oxidized FAD to the FAD•− state with a very positive midpoint potential of ~ +125 mV, although no further reduction could be observed. We could also demonstrate that the terminal tryptophan of the conserved triad, W342, is directly involved in electron transfer; however, photoreduction could not be completely inhibited in a W342F mutant. The investigation of another mutation close to the FAD cofactor, C416N, rather unexpectedly reveals accumulation of a protonated flavin radical on a timescale of several seconds. The obtained data are critically discussed with the ones obtained from another protein, Escherichia coli photolyase, and we conclude that the amino acid opposite N(5) of the isoalloxazine moiety of FAD is able to (de)stabilize the protonated FAD radical but not to significantly modulate the kinetics of any light-inducted reactions. [ABSTRACT FROM AUTHOR]

Time-resolved electron paramagnetic resonance (TREPR) spectroscopy is shown to be a powerful tool to characterize triplet excitons of conjugated polymers. The resulting spectra are highly sensitive to the orientation of the molecule. In thin films cast on PET film, the molecules' orientation with respect to the surface plane can be determined, providing access to sample morphology on a microscopic scale. Surprisingly, the conjugated polymer investigated here, a promising material for organic photovoltaics, exhibits ordering even in bulk samples. Orientation effects may significantly influence the efficiency of solar cells, thus rendering proper control of sample morphology highly important. [ABSTRACT FROM AUTHOR]

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This phase I study tested the safety, feasibility, pharmacokinetics and pharmacodynamics of cisplatin administered as hyperthermic intraoperative intraperitoneal chemoperfusion (HIPEC) in patients with platinum-sensitive recurrent epithelial ovarian cancer (EOC) undergoing secondary cytoreductive surgery followed by postoperative platinum-based intravenous chemotherapy. Twelve patients with operable, recurrent platinum-sensitive EOC (recurrence ≥6 months after first-line therapy) were included according to the classical 3+3 dose-escalation design at three dose levels-60, 80 and 100 mg/m2. After surgical cytoreduction, a single dose of cisplatin was administered via HIPEC for 90 min at 41-43°C. Postoperatively, all patients were treated with standard intravenous platinum-based combination chemotherapy. One of six patients experienced a dose-limiting toxicity (grade 3 renal toxicity) at a dose of 100 mg/m2. The remaining five patients treated with 100 mg/m2 tolerated their treatment well. The recommended phase II dose was established at 100 mg/m2. The mean peritoneal-to-plasma AUC ratio was 19·5 at the highest dose level. Cisplatin-induced DNA adducts were confirmed in tumor samples. Common postoperative grade 1-3 toxicities included fatigue, postoperative pain, nausea, and surgical site infection. The ability to administer standard intravenous platinum-based chemotherapy after HIPEC was uncompromised. Cisplatin administered as HIPEC at a dose of 100 mg/m2 has an acceptable safety profile in selected patients undergoing secondary cytoreductive surgery for platinum-sensitive recurrent EOC. Favorable pharmacokinetic and pharmacodynamic properties of HIPEC with cisplatin were confirmed at all dose levels, especially at 100 mg/m2. The results are encouraging to determine the efficacy of HIPEC as a complementary treatment in patients with EOC. [ABSTRACT FROM AUTHOR]

Nanocrystalline zirconia particles with a diameter of about 4 nm were obtained by microwave-assisted decomposition of basic zirconium acetate in ethoxyethanol. The reaction yields optically transparent and stable dispersions, which can ideally be employed for the manufacture of dielectric thin films by spin-coating followed by a subsequent annealing step. The influence of the processing conditions on the electronic performance of an electrical capacitor device built from this nanomaterial was studied. Electron paramagnetic resonance spectroscopic studies exclude the presence of point defects within the zirconia bulk; however, they reveal the presence of surface-related paramagnetic species. [ABSTRACT FROM AUTHOR]

Background Cardiogoniometry (CGM) is a novel resting electrocardiac method based on computer-generated three-dimensional data derived from cardiac potentials. The purpose of this study was to determine CGM's and electrocardiography's (ECG) accuracy for detecting myocardial ischemia and/or lesions in comparison with stress/rest myocardial perfusion scintigraphy (single photon emission computer tomography [SPECT]). Method A cohort of consecutively enrolled patients (n = 100) with suspected or known coronary artery disease (mean age 67.8 years, 52% female) were examined by CGM and resting ECG before stress/rest myocardial scintigraphy. Results Pathological scintigraphy findings at adenosine stress perfusion (ASP) and/or rest were conclusively identified in 21 patients. Diagnostic sensitivity was 71% for CGM and 24% for ECG, specificity was 70% for CGM and 95% for ECG. Reversible ischemia was diagnosed in 16 of 21 patients with pathological scintigraphy results. In this subgroup, sensitivity was 67% for CGM and 25% for ECG. Conclusions At rest, the sensitivity of a CGM significantly surmounts that of a standard 12-lead ECG for detection of isolated myocardial ischemia or myocardial lesions revealed by scintigraphy/SPECT; specificity is in a reasonable range. CGM's ease of use and its considerable agreement with the results of myocardial scintigraphy, suggests a possible role for patient screening in the primary care setting. [ABSTRACT FROM AUTHOR]

The perhalogenated closo-dodecaborate dianions [B12X12]2− (X=H, F, Cl, Br, I) are three-dimensional counterparts to the two-dimensional aromatics C6X6 (X=H, F, Cl, Br, I). Whereas oxidation of the parent compounds [B12H12]2− and benzene does not lead to isolable radicals, the perhalogenated analogues can be oxidized by chemical or electrochemical methods to give stable radicals. The chemical oxidation of the closo-dodecaborate dianions [B12X12]2− with the strong oxidizer AsF5 in liquid sulfur dioxide ( lSO2) yielded the corresponding radical anions [B12X12] ⋅− (X=F, Cl, Br). The presence of radical ions was proven by EPR and UV/Vis spectroscopy and supported by quantum chemical calculations. Use of an excess amount of the oxidizing agent allowed the synthesis of the neutral perhalogenated hypercloso-boranes B12X12 (X=Cl, Br). These compounds were characterized by single-crystal X-ray diffraction of dark blue B12Cl12 and [Na(SO2)6][B12Br12] ⋅B12Br12. Sublimation of the crude reaction products that contained B12X12 (X=Cl, Br) resulted in pure dark blue B12Cl12 or decomposition to red B9Br9, respectively. The energetics of the oxidation processes in the gas phase were calculated by DFT methods at the PBE0/def2-TZVPP level of theory. They revealed the trend of increasing ionization potentials of the [B12X12]2− dianions by going from fluorine to bromine as halogen substituent. The oxidation of all [B12X12]2− dianions was also studied in the gas phase by mass spectrometry in an ion trap. The electrochemical oxidation of the closo-dodecaborate dianions [B12X12]2− (X=F, Cl, Br, I) by cyclic and Osteryoung square-wave voltammetry in liquid sulfur dioxide or acetonitrile showed very good agreement with quantum chemical calculations in the gas phase. For [B12X12]2− (X=F, Cl, Br) the first and second oxidation processes are detected. Whereas the first process is quasi-reversible (with oxidation potentials in the range between +1.68 and +2.29 V ( lSO2, versus ferrocene/ferrocenium (Fc0/+))), the second process is irreversible (with oxidation potentials ranging from +2.63 to +2.71 V ( lSO2, versus Fc0/+)). [B12I12]2− showed a complex oxidation behavior in cyclic voltammetry experiments, presumably owing to decomposition of the cluster anion under release of iodide, which also explains the failure to isolate the respective radical by chemical oxidation. [ABSTRACT FROM AUTHOR]

Background We investigate the frequency of esophageal tissue injury (ETI) following ablation of atrial fibrillation (AF) using the pulmonary vein ablation catheter (PVAC) ascertained by esophageal endoscopy (ESE) and corresponding magnetic resonance imaging (MRI). Methods A total of 41 patients with symptomatic AF presenting for pulmonary vein isolation (PVI) were included consecutively in two observational groups. Group A received MRI the day before and ESE plus MRI within 3-4 weeks following the ablation procedure using the PVAC. Group B received MRI the day before and ESE plus MRI within 2 days after PVI. MRI included T2-weighted and T1-weighted postcontrast with fat suppression (fs) and late-enhancement scans to demonstrate postprocedural edema and contrast enhancement of the esophageal wall. Results A total of 13 (32%) patients were enrolled in Group A (26 ± 11 days post-PVI), and 28 (68%) patients in Group B (2 ± 0.6 days post-PVI). ETI was found by ESE in one (2%) patient (Group B) and resolved under conservative therapy. Corresponding MRI showed a false negative result with no alterations of esophageal structures using T1-weighted, T2-weighted, and late enhancement scans. In addition, false positive results were demonstrated by late-enhancement MRI in five (12%) patients (three patients in Group A and two patients in Group B), which could not be verified by corresponding ESE. Conclusions Endoluminal ETI is a rare but possible complication, which should be considered following PVAC procedures. MRI of the esophagus is currently not a reliable screening method due to false positive and negative findings compared to ESE. [ABSTRACT FROM AUTHOR]

Blue-light sensitive photoreceptory BLUF domains are flavoproteins, which regulate various, mostly stress-related processes in bacteria and eukaryotes. The photoreactivity of the flavin adenine dinucleotide (FAD) cofactor in three BLUF domains from Rhodobacter sphaeroides, Synechocystis sp . PCC 6803 and Escherichia coli have been studied at low temperature using time-resolved electron paramagnetic resonance. Photoinduced flavin triplet states and radical-pair species have been detected on a microsecond time scale. Differences in the electronic structures of the FAD cofactors as reflected by altered zero-field splitting parameters of the triplet states could be correlated with changes in the amino-acid composition of the various BLUF domains' cofactor binding pockets. For the generation of the light-induced, spin-correlated radical-pair species in the BLUF domain from Synechocystis sp. PCC 6803, a tyrosine residue near the flavin's isoalloxazine moiety plays a critical role. [ABSTRACT FROM AUTHOR]