bluuebunny/crossref_metadata_2025 huggingface dataset:
Veracity is in the eye of the beholder: A lens model examination of consistency and deception
Authors: Hudson Charlotte A. , Vrij Aldert , Akehurst Lucy , Hope Lorraine , Satchell Liam P.
Published: April 2020

Research has attempted to explain perceived cues to deception based upon self‐report of what participants believe are ‘good’ cues to deception, or self‐report of what cues participants say they base their veracity judgements on. However, it is not clear to what extent participants can accurately self‐report what influences their decision‐making. Using a within‐subjects design, 285 participants completed a questionnaire regarding their beliefs about deception before rating a selection of truthful and deceptive statements on a variety of cues. Expert coders also rated the statements for the same cues. Laypeople and expert coders do not conceptualise between‐subject consistency in the same way. A lens model showed that whilst perceptions of cues, such as consistency and amount of detail, influence veracity judgements, these perceptions (and overall veracity judgements) are mostly inaccurate. Fundamentally, there seems to be inconsistencies between how deception research examines consistency and how it is understood and used by laypeople.
Rational Chemical Multifunctionalization of Graphene Interface Enhances Targeted Cancer Therapy
Authors: Lucherelli Matteo Andrea , Yu Yue , Reina Giacomo , Abellán Gonzalo , Miyako Eijiro , Bianco Alberto
Published: April 2020

The synthesis of a drug delivery platform based on graphene was achieved through a step‐by‐step strategy of selective amine deprotection and functionalization. The multifunctional graphene platform, functionalized with indocyanine green, folic acid, and doxorubicin showed an enhanced anticancer activity. The remarkable targeting capacity for cancer cells in combination with the synergistic effect of drug release and photothermal properties prove the great advantage of a combined chemo‐ and phototherapy based on graphene against cancer, opening the doors to future therapeutic applications of this type of material.
Doppelrotoren mit fluktuierenden Achsen: Domino‐Rotation und Katalyse der Azid‐Alkin‐Huisgen‐Cycloaddition
Authors: Goswami Abir , Schmittel Michael
Published: April 2020

Die einfache Herstellung der Mehrkomponentengeräte [Cu4(A)2]4+ und [Cu2(A)(B)]2+, beides Rotoren mit fluktuierenden Achsen, die sich in einer Domino‐Rotation befinden, unterstreicht das Potenzial der Selbstsortierung. Das Konzept der Domino‐Rotation erfordert die Interkonversion von Achse und Rotator, was die räumlich‐zeitliche Entkopplung zweier entarteter Austauschprozesse in [Cu4(A)2]4+ ermöglicht, die mit 142 kHz auftreten. Die Addition von zwei Äquivalenten B zum Rotor [Cu4(A)2]4+ führte zum heteromeren zweiachsigen Rotor [Cu2(A)(B)]2+ mit zwei unterschiedlichen Austauschprozessen (64.0 kHz und 0.55 Hz). Die Bewegung, die eine Spaltung der Pyridin→Zinkporphyrin‐Bindung erfordert, ist 1.2×105‐mal schneller als diejenige, die über eine Spaltung der Terpyridin→[Cu(phenAr2)]+‐Bindung erfolgt. Schließlich sind beide Rotoren wegen ihres Kupfer(I)‐Anteils Katalysatoren. Es konnte gezeigt werden, dass der schnelle Domino‐Rotor (142 kHz) die Produktinhibierung bei der Katalyse der Azid‐Alkin‐Huisgen‐Cycloaddition unterdrückt.
Intrinsische elektrokatalytische Aktivitätssteuerung von M‐N‐C‐Einzelatom‐Katalysatoren für die Sauerstoffreduktionsreaktion
Authors: Zhao Chang‐Xin , Li Bo‐Quan , Liu Jia‐Ning , Zhang Qiang
Published: April 2020

Einzelatom‐Katalysatoren (SACs) mit hochaktiven, auf Substraten atomar verteilten Reaktionsstellen haben Vorteile in Bezug auf die maximale atomare Effizienz, die Vielfalt chemischer Strukturen und ihr außerordentliches katalytisches Leistungsvermögen. M‐N‐C‐SACs (M=Übergangsmetallatom) weisen eine optimale elektrokatalytische Aktivität für die Sauerstoffreduktionsreaktion (ORR) auf. Bisher wurden die Prinzipien der Steuerung der intrinsischen elektrokatalytischen Aktivität von M‐N‐C‐Aktivstellen jedoch nicht ausreichend dargestellt. In diesem Aufsatz werden Steuerungsstrategien zur Förderung der intrinsischen elektrokatalytischen ORR‐Aktivität von M‐N‐C‐SACs zusammengestellt, indem jeweils die Metall‐Zentralatome, die koordinierenden Atome, die Umgebungsatome und die Gastgruppen modifiziert werden. Um ein tieferes Verständnis der Struktur‐Leistungs‐Beziehung zu gewinnen, werden theoretische und experimentelle Studien einbezogen. Schließlich werden Richtungen für die weitere Entwicklung von M‐N‐C‐SACs für die elektrokatalytische ORR und andere Reaktionen vorgeschlagen.
Identifizierung von halbleitenden Bereichen in thermisch behandeltem monolagigem Oxo‐funktionalisiertem Graphen
Authors: Wang Zhenping , Yao Qirong , Neumann Christof , Börrnert Felix , Renner Julian , Kaiser Ute , Turchanin Andrey , Zandvliet Harold J. W. , Eigler Siegfried
Published: April 2020

Die thermische Zersetzung von Graphenoxid (GO) ist auf atomarer Ebene ein komplexer Prozess und noch nicht vollständig verstanden. In dieser Untersuchung wurde eine Unterklasse von GO verwendet, oxofunktionalisiertes Graphen (oxo‐G), um die thermische Disproportionierung zu untersuchen. Wir stellen den Einfluss des Erhitzens auf die elektronischen Eigenschaften einer einschichtigen oxo‐G‐Flocke vor und korrelieren die chemische Zusammensetzung und die Topographie durch Zwei‐Kontakt‐Transportmessungen, XPS, TEM, FTIR und STM. Überraschenderweise fanden wir heraus, dass oxo‐G, das auf 300 °C erhitzt wurde, neben Graphendomänen und Löchern auch C‐C‐sp3‐Bereiche und möglicherweise C‐O‐C‐Bindungen enthält. Auffallend ist, dass diese C‐O‐C/C‐C‐sp3‐getrennten sp2‐Bereiche mit wenigen Nanometern Durchmesser Halbleitereigenschaften mit einer Bandlücke von etwa 0.4 eV aufweisen. Wir schlagen vor, dass sp3‐Bereiche konjugierte sp2‐C‐Atomgruppen einschließen, was zu den lokalen Halbleitereigenschaften führt. Dementsprechend ist Graphen mit sp3‐C in Doppelschichtbereichen eine potentielle Klasse von Halbleitern und ein potentielles Ziel für zukünftige chemische Modifikationen.
Double Rotors with Fluxional Axles: Domino Rotation and Azide–Alkyne Huisgen Cycloaddition Catalysis
Authors: Goswami Abir , Schmittel Michael
Published: April 2020

The simple preparation of the multicomponent devices [Cu4(A)2]4+ and [Cu2(A)(B)]2+, both rotors with fluxional axles undergoing domino rotation, highlights the potential of self‐sorting. The concept of domino rotation requires the interconversion of axle and rotator, allowing the spatiotemporal decoupling of two degenerate exchange processes in [Cu4(A)2]4+ occurring at 142 kHz. Addition of two equiv of B to rotor [Cu4(A)2]4+ afforded the heteromeric two‐axle rotor [Cu2(A)(B)]2+ with two distinct exchange processes (64.0 kHz and 0.55 Hz). The motion requiring a pyridine→zinc porphyrin bond cleavage is 1.2×105 times faster than that operating via a terpyridine→[Cu(phenAr2)]+ rupture. Finally, both rotors are catalysts due to their copper(I) content. The fast domino rotor (142 kHz) was shown to suppress product inhibition in the catalysis of the azide–alkyne Huisgen cycloaddition.
Intrinsic Electrocatalytic Activity Regulation of M–N–C Single‐Atom Catalysts for the Oxygen Reduction Reaction
Authors: Zhao Chang‐Xin , Li Bo‐Quan , Liu Jia‐Ning , Zhang Qiang
Published: April 2020

Single‐atom catalysts (SACs) with highly active sites atomically dispersed on substrates exhibit unique advantages regarding maximum atomic efficiency, abundant chemical structures, and extraordinary catalytic performances for multiple important reactions. In particular, M–N–C SACs (M=transition metal atom) demonstrate optimal electrocatalytic activity for the oxygen reduction reaction (ORR) and have attracted extensive attention recently. Despite substantial efforts in fabricating various M–N–C SACs, the principles for regulating the intrinsic electrocatalytic activity of their active sites have not been sufficiently studied. In this Review, we summarize the regulation strategies for promoting the intrinsic electrocatalytic ORR activity of M–N–C SACs by modulation of the center metal atoms, the coordinated atoms, the environmental atoms, and the guest groups. Theoretical calculations and experimental investigations are both included to afford a comprehensive understanding of the structure–performance relationship. Finally, future directions of developing advanced M–N–C SACs for electrocatalytic ORR and other analogous reactions are proposed.
Identification of Semiconductive Patches in Thermally Processed Monolayer Oxo‐Functionalized Graphene
Authors: Wang Zhenping , Yao Qirong , Neumann Christof , Börrnert Felix , Renner Julian , Kaiser Ute , Turchanin Andrey , Zandvliet Harold J. W. , Eigler Siegfried
Published: April 2020

The thermal decomposition of graphene oxide (GO) is a complex process at the atomic level and not fully understood. Here, a subclass of GO, oxo‐functionalized graphene (oxo‐G), was used to study its thermal disproportionation. We present the impact of annealing on the electronic properties of a monolayer oxo‐G flake and correlated the chemical composition and topography corrugation by two‐probe transport measurements, XPS, TEM, FTIR and STM. Surprisingly, we found that oxo‐G, processed at 300 °C, displays C−C sp3‐patches and possibly C−O−C bonds, next to graphene domains and holes. It is striking that those C−O−C/C−C sp3‐separated sp2‐patches a few nanometers in diameter possess semiconducting properties with a band gap of about 0.4 eV. We propose that sp3‐patches confine conjugated sp2‐C atoms, which leads to the local semiconductor properties. Accordingly, graphene with sp3‐C in double layer areas is a potential class of semiconductors and a potential target for future chemical modifications.
Efficient reduction of CO2 to CO by Ag3PO4/TiO2 photocatalyst under ultraviolet and visible light irradiation
Authors: Qi Fengjiao , Li Hailong , Yang Zequn , Zhao Jiexia , Hu Yingchao , Liu Hui
Published: April 2020

Efficient conversion of carbon dioxide (CO2) into energy‐bearing compounds using abundant solar energy is a promising technique that simultaneously responds to the concerns on global warming and energy shortage. The purpose of this study was to find a photocatalyst that can efficiently utilize sunlight for an efficient reduction of CO2 to energy‐bearing carbon monoxide (CO). Silver phosphate/titanium dioxide (Ag3PO4/TiO2) hetero‐structured photocatalysts with different mole ratios of Ag3PO4 to TiO2 were synthesized by a facile precipitation method, and for the first time used for photocatalytic CO2 reduction by water vapor (H2O). When the mole ratio of Ag3PO4 to TiO2 was 0.15, the as‐synthesized photocatalyst exhibited the highest CO2 reduction activity under ultraviolet (UV) and visible light irradiation, with the productivity of CO reaching as high as 74.84 μmol·g−1 within a 3‐h experiment. This is 3.5 and 11.7 times higher than that for the bare Ag3PO4 and TiO2, respectively. The characterization results indicate that a heterojunction was formed between Ag3PO4 and TiO2, which significantly promoted the photocatalytic CO2 reduction reactions through facilitating the separation and migration of the photogenerated charge carriers. This study verified that the Ag3PO4/TiO2 catalyst can effectively utilize solar energy for reduction of CO2 to CO.
Internal stress analysis of epoxy adhesively‐boned joints based on their thermomechanical properties at cryogenic temperature
Authors: Li Hong , Wang Kun , Chen Gong , Sun Lingyu , Yang Jiping
Published: April 2020

Internal stress analysis is essential to structural design of materials applied in cryogenic engineering. In this contribution, thermomechanical properties including dynamic thermomechanical properties and thermal expansion behavior of four epoxy resins, namely the polyurethane modified epoxy resin (PUE), diglycidyl ether of bisphenol A (DGEBA), tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM) and triglycidyl‐p‐aminophenol (TGPAP) were studied by dynamic thermomechanical analysis. Internal stress of the epoxy layer in the bonded joint was calculated based on the thermomechanical properties. Meanwhile, the structure‐cryogenic property relationship of epoxy resins were investigated. Results demonstrate that internal stress in the four epoxies bonded joints is 6 ~ 21 MPa at −150°C, and is positively correlated with the average thermal expansion coefficient (CTE) of epoxy resins. TGDDM and TGPAP showed higher retention of lap shear strength both at −196°C and after temperature cycling due to their lower CTE. Morphology of the fractured surface of bonded joints demonstrated that internal stress is responsible for the severe interface failure at −196°C. It reveals that selection of epoxy resins with low CTE is beneficial for designing high‐performance epoxy adhesive systems served at cryogenic temperature.
Thin film composite nanofiltration membranes with polystyrene sodium sulfonate–polypiperazinetrimesamide semi‐interpenetrating polymer network active layer
Authors: Polisetti Veerababu , Ray Paramita
Published: April 2020

The present work depicts the preparation, characterization, and application of thin film composite nanofiltration (TFCNF) membranes. TFCNF membranes having polyacrylonitrile ultrafiltration support with active layer made of polystyrene sodium sulfonate–polypiperazinetrimesamide semi‐interpenetrating polymer network (semi‐IPN) are prepared. Membranes with semi‐IPN active layer exhibited better hydrophilicity, higher negative zeta potential and surface roughness in comparison with NF membranes having virgin polypiperazinetrimesamide as the active layer. Semi‐IPN membranes exhibited pure water permeability 103 ± 10 LMH at 150 psi pressure and rejection ratio of bivalent to monovalent salts as 2.7, whereas for virgin polypiperazinetrimesamide membrane the values, are 42 ± 5 LMH and 2.1, respectively. The semi‐IPN NF membranes showed better antifouling behavior than the virgin polypiperazinetrimesamide membrane. The flux recovery ratio and total fouling ratio of semi‐IPN NF membrane were observed 97.8 and 3.3% whereas for polypiperazinetrimesamide NF membranes, the values are 90.9 and 10.5%, respectively.
A simple, non‐toxic method for separating seeds based on density, and its application in isolating Arabidopsis thaliana seed oil mutants
Authors: Dean Gillian H. , Pang Flora , Haughn George W. , Kunst Ljerka
Published: April 2020

Premise

Seed oil is an economically important trait in Brassica oilseed crops. A novel method was developed to isolate Arabidopsis thaliana seeds with altered oil content.

Methods and Results

In A. thaliana, seed oil content is correlated with seed density, with high‐oil seeds being less dense than wild type and tending to float in solution, and low‐oil seeds being denser and tending to sink. In contrast to previous methods, which used toxic chemicals and density gradient centrifugation, different concentrations of calcium chloride (CaCl2) were employed to separate seeds without the need for centrifugation. The method was validated using known seed oil mutants, and 120,822 T‐DNA mutagenized A. thaliana lines were then screened for novel seed density phenotypes.

Conclusions

A number of candidate mutants, as well as new alleles of two genes known to influence seed oil biosynthesis, were successfully isolated.
Inferring the impacts of evolutionary history and ecological constraints on spore size and shape in the ferns
Authors: Barrington David S. , Patel Nikisha R. , Southgate Morgan W.
Published: April 2020

Premise

In the ferns, cell size has been explored with spores, which are largely uniform within species, produced in abundance, and durable. However, spore size and shape have been variously defined, and the relationship of these traits to genome size has not been well established. Here, we explore the variation in fern spore size and shape by ploidy level and genome size.

Methods

Measurements of spore dimensions for two study sets of ferns, Polystichum and Adiantum, both including diploid and tetraploid taxa, provided the basis for computing estimates of shape and size as defined here. These traits were compared between and within ploidy levels and regressed with genome size estimates from flow cytometry analysis.

Results

All size traits were strongly correlated with genome size; the shape trait was weakly correlated. Tetraploids were larger than diploids as expected; the spores of some closely related diploid species were also significantly different in size.

Discussion

Researchers with access to a student‐grade compound microscope can develop a valid estimate of relative genome size for ferns. These estimates provide enough resolution to infer ploidy level and explore the relationship between genome size, habitat, and physiological constraints for species within ploidy level.
Confirmation of a wear‐compensation mechanism in dental roots of ruminants
Authors: Ackermans Nicole L. , Martin Louise F. , Codron Daryl , Kircher Partick R. , Richter Henning , Clauss Marcus , Hatt Jean‐Michel
Published: April 2020

Diet affects many factors of an animal's anatomy, but teeth are a specific focus of dietary research, as their durability lends them to record information on a large variety of scales. Abrasive diets like those of grazing herbivores are known to wear down teeth, but how that wear affects tooth growth and the relations between its different morphological components is rarely investigated. Seven pelleted diets varying in abrasive size and concentration were fed over a 17‐month period to 49 sheep (Ovis aries), of which n = 39 qualified for morphology measurements. Using computed tomography, scans of the skulls were made over the course of the experiment, and the impact of diet‐related wear was observed on tooth volume and morphology, including the position of dental burr marks, over time. Digital caliper measurements were applied to 3D renderings of the teeth, and the volume of crown and root segments were investigated separately. We aimed to detect a signal of root growth compensating for wear, and test if this mechanism would be affected by dietary abrasives. Crown‐segment volume loss was correlated to root‐segment volume gain. Height and burr mark measurements indicated a much higher experimental tooth wear than that previously reported for free‐ranging animals. The reason for this is unclear. There was no relationship between tooth height and dentine basin depth. For all parameters, there was no effect of diet; hence, while the measurements corroborate general understanding of tooth wear and compensatory processes, these methods appear not suitable to assess subtle differences between feeding regimes.
Konventionelle Abbruchplanung von Kühltürmen unter Verwendung eines progressiven Schadensmodells
Authors: Giesa Tristan , Rost Markus
Published: April 2020

Der circa 160 m hohe Kühlturm des Kernkraftwerks Mülheim‐Kärlich wurde konventionell ohne Sprengung in einem mehrstufigen Prozess abgebrochen. Der Prozess unterteilt sich in die Phasen: vertikaler Zugang, maschineller und automatisierter Abbruch der oberen Kühlturmhälfte, kontrollierter Kollaps der unteren Kühlturmhälfte, Restabbruch. Es wird eine neue Methodik für den Abbruch präsentiert, bei dem die Struktur erst durch Schnitte in der Kühlturmschale und dann durch das sukzessive Entfernen von Stützen geschwächt wurde. Ein definierter Impuls, das Entfernen eines kritischen Stützelements, führt zu einem dem Abbruch mit Sprengstoff ähnlichen Versagen. Der Abbruchprozess wurde mithilfe der Finite‐Elemente‐Analyse modelliert. Ein progressives Versagensmodell, das anhand von Materialversuchen kalibriert und validiert wurde, konnte das Versagen der Schale präzise vorhersagen. Solche Analysetechniken können effektiv eingesetzt werden, um die Sicherheit des Abbruchs mittels kontrollierten Einsturzes hinsichtlich Einsturzverhalten, Fallrichtung und Erschütterungsprognose zu verbessern.
Insulin production from hiPSC‐derived pancreatic cells in a novel wicking matrix bioreactor
Authors: Amini Nooshin , Paluh Janet L. , Xie Yubing , Saxena Vinit , Sharfstein Susan T.
Published: April 2020

Clinical use of pancreatic β islets for regenerative medicine applications requires mass production of functional cells. Current technologies are insufficient for large‐scale production in a cost‐efficient manner. Here, we evaluate advantages of a porous cellulose scaffold and demonstrate scale‐up to a wicking matrix bioreactor as a platform for culture of human endocrine cells. Scaffold modifications were evaluated in a multiwell platform to find the optimum surface condition for pancreatic cell expansion followed by bioreactor culture to confirm suitability. Preceding scale‐up, cell morphology, viability, and proliferation of primary pancreatic cells were evaluated. Two optimal surface modifications were chosen and evaluated further for insulin secretion, cell morphology, and viable cell density for human‐induced pluripotent stem cell‐derived pancreatic cells at different stages of differentiation. Scale‐up was accomplished with uncoated, amine‐modified cellulose in a miniature bioreactor, and insulin secretion and cell metabolic profiles were determined for 13 days. We achieved 10‐fold cell expansion in the bioreactor along with a significant increase in insulin secretion compared with cultures on tissue culture plastic. Our findings define a new method for expansion of pancreatic cells a on wicking matrix cellulose platform to advance cell therapy biomanufacturing for diabetes.
Introducing underrepresented high school students to software engineering: Using the micro:bit microcontroller to program connected autonomous cars
Authors: Kelly Dylan G. , Seeling Patrick
Published: April 2020

Outreach that considers underrepresented groups has become one particular push to increase participation in Science, Technology, Engineering, and Math‐related disciplines, with Computer Science and Software Engineering representing one particular domain. We describe our outreach programming employing the micro:bit microcontroller environment for hands‐on software development and how students change their high‐level domain knowledge and attitudes. We find that overall, students were gaining general knowledge and slight increases in their positive attitudes towards a computer science‐related post‐secondary education. We also find differences between incoming knowledge level groups and self‐perception as well as performance differences. We also note a slight majority of students indicated that they liked our approach and that the utilization of the micro:bit microcontroller overall was worthwhile. Future iterations of our programming will utilize these findings and add additional data gathering efforts supplanting the current pre‐ and posttest instruments.
Gatekeeping in cancer clinical trials in Canada: The ethics of recruiting the “ideal” patient
Authors: Bell Jennifer A. H. , Kelly Mary T. , Gelmon Karen , Chi Kim , Ho Anita , Rodney Patricia , Balneaves Lynda G.
Published: April 2020

Background

Perspectives of clinical trial (CT) personnel on accrual to oncology CTs are relatively absent from the literature. This study explores CT personnel's experience recruiting patients to oncology CTs.

Methods

A qualitative study design was utilized. In‐depth, individual interviews with 12 oncology CT personnel were conducted, including six CT nurses and six physician‐investigators. Interviews were digitally recorded and transcribed verbatim. Data were subjected to thematic and ethical analysis to identify key concepts and themes.

Results

CT personnel reported considering two ethical commitments in CT recruitment: maintaining trial integrity and ensuring patient autonomy through obtaining informed consent. The process of gatekeeping emerged as a way to navigate these ethical commitments during CT accrual. Gatekeeping was influenced by: (a) perceptions of patients’ personal suitability for a trial, and (b) healthcare resources and infrastructure. CT personnel's discernment of personal suitability was influenced by patients’ cognitive and mental health status, language and cultural background, geographic location, family support, and disease status. Three structural factors impacted gatekeeping: complexity of CTs, consent process, and time limitations in the healthcare system. CT personnel experienced most factors as constraints to accrual and gaining patients’ informed consent.

Conclusion

CT personnel discussed navigating ethical challenges in CT recruitment by offering enrollment to specific patient populations, exacerbating other ethical tensions. Systems‐level strategies are needed to address barriers to ethical CT recruitment. Future research should investigate the role of policies and/or tools (eg, decision aids) to support patients and CT personnel's discussions about CT participation, promote more ethical recruitment, and potentially increase accrual.
Recent Applications of Carbon‐Nitrogen Lyases in Asymmetric Synthesis of Noncanonical Amino Acids and Heterocyclic Compounds
Authors: Zhang Jielin , Abidin Mohammad Z. , Saravanan Thangavelu , Poelarends Gerrit J.
Published: April 2020

Carbon‐nitrogen (C−N) lyases are enzymes that normally catalyze the cleavage of C−N bonds. Reversing this reaction towards carbon‐nitrogen bond formation can be a powerful approach to prepare valuable compounds that could find applications in everyday life. This review focuses on recent (last five years) applications of native and engineered C−N lyases, either as stand‐alone biocatalysts or as part of multienzymatic and chemoenzymatic cascades, in enantioselective synthesis of noncanonical amino acids and dinitrogen‐fused heterocycles, which are useful tools for neurobiological research and important synthetic precursors to pharmaceuticals and food additives.
MXene‐Based Nanocomposites for Energy Conversion and Storage Applications
Authors: Zhang Aitang , Liu Rui , Tian Jinmi , Huang Weiguo , Liu Jingquan
Published: April 2020

Novel nanomaterials and advanced nanotechnology continuously push forward the rapid development of sustainable energy conversion and storage equipment. An emerging family of two‐dimensional transition‐metal carbides, nitrides and carbonitrides, also known as MXenes, have attracted increasing attention and in depth investigation. Benefitting from their unique intrinsic properties, MXenes have attracted significant attention and they have been considered as promising candidate materials for the development of environmentally friendly energy resources. A large number of studies show that MXenes have great potential in energy conversion and storage fields. Despite of their exceptional properties, MXenes also have some inherent characteristics, such as low capacities and unstable retention performances, which severely hinder their prospect applications in energy conversion and storage fields. In this Minireview, the latest progress on MXenes and their hybrid composites with small molecules, polymers, carbon or metal ions, and their applications in energy conversion and storage fields is highlighted, including their use in different types of batteries, supercapacitors, hydrogen/oxygen evolution reactions, electromagnetic interference absorption/shielding and solar steam generation. In addition, the critical challenges and further development prospects of MXene‐based materials are also introduced.
Fast Acquisition of Proton‐Detected HETCOR Solid‐State NMR Spectra of Quadrupolar Nuclei and Rapid Measurement of NH Bond Lengths by Frequency Selective HMQC and RESPDOR Pulse Sequences
Authors: Wijesekara Anuradha V. , Venkatesh Amrit , Lampkin Bryan J. , VanVeller Brett , Lubach Joseph W. , Nagapudi Karthik , Hung Ivan , Gor'kov Peter L. , Gan Zhehong , Rossini Aaron J.
Published: April 2020

Fast magic‐angle spinning (MAS), frequency selective (FS) heteronuclear multiple quantum coherence (HMQC) experiments which function in an analogous manner to solution SOFAST HMQC NMR experiments, are demonstrated. Fast MAS enables efficient FS excitation of 1H solid‐state NMR signals. Selective excitation and observation preserves 1H magnetization, leading to a significant shortening of the optimal inter‐scan delay. Dipolar and scalar 1H{14N} FS HMQC solid‐state NMR experiments routinely provide 4‐ to 9‐fold reductions in experiment times as compared to conventional 1H{14N} HMQC solid‐state NMR experiments. 1H{14N} FS resonance‐echo saturation‐pulse double‐resonance (RESPDOR) allowed dipolar dephasing curves to be obtained in minutes, enabling the rapid determination of NH dipolar coupling constants and internuclear distances. 1H{14N} FS RESPDOR was used to assign multicomponent active pharmaceutical ingredients (APIs) as salts or cocrystals. FS HMQC also provided enhanced sensitivity for 1H{17O} and 1H{35Cl} HMQC experiments on 17O‐labeled Fmoc‐alanine and histidine hydrochloride monohydrate, respectively. FS HMQC and FS RESPDOR experiments will provide access to valuable structural constraints from materials that are challenging to study due to unfavorable relaxation times or dilution of the nuclei of interest.
Design and Synthesis of 56 Shape‐Diverse 3D Fragments
Authors: Downes Thomas D. , Jones S. Paul , Klein Hanna F. , Wheldon Mary C. , Atobe Masakazu , Bond Paul S. , Firth James D. , Chan Ngai S. , Waddelove Laura , Hubbard Roderick E. , Blakemore David C. , De Fusco Claudia , Roughley Stephen D. , Vidler Lewis R. , Whatton Maria Ann , Woolford Alison J.‐A. , Wrigley Gail L. , O'Brien Peter
Published: April 2020

Fragment‐based drug discovery is now widely adopted for lead generation in the pharmaceutical industry. However, fragment screening collections are often predominantly populated with flat, 2D molecules. Herein, we describe a workflow for the design and synthesis of 56 3D disubstituted pyrrolidine and piperidine fragments that occupy under‐represented areas of fragment space (as demonstrated by a principal moments of inertia (PMI) analysis). A key, and unique, underpinning design feature of this fragment collection is that assessment of fragment shape and conformational diversity (by considering conformations up to 1.5 kcal mol−1 above the energy of the global minimum energy conformer) is carried out prior to synthesis and is also used to select targets for synthesis. The 3D fragments were designed to contain suitable synthetic handles for future fragment elaboration. Finally, by comparing our 3D fragments with six commercial libraries, it is clear that our collection has high three‐dimensionality and shape diversity.
Direct Mechanocatalysis: Using Milling Balls as Catalysts
Authors: Pickhardt Wilm , Grätz Sven , Borchardt Lars
Published: April 2020

Direct mechanocatalysis describes catalytic reactions under the involvement of mechanical energy with the distinct feature of milling equipment itself being the catalyst. This novel type of catalysis features no solubility challenges of the catalysts nor the substrate and on top offering most facile way of separation.
Octaboraneyl Complexes of Nickel: Monomers for Redox‐Active Coordination Polymers
Authors: Drover Marcus W. , Dufour Maeve C. , Lesperance‐Nantau Lindsay A. , Noriega Rayni P. , Levin Kirill , Schurko Robert W.
Published: April 2020

Herein, we establish the preparation, characterization, and reactivity of a new diphosphine ligand, 1,2‐bis(di(3‐dicyclohexylboraneyl)propylphosphino)ethane (P2BCy4), a scaffold that contains four pendant boranes. An entryway into the coordination chemistry of P2BCy4 is established by using nickel, providing the octaboraneyl complex [Ni(P2BCy4)2]—this species contains a boron‐rich secondary coordination sphere that reacts readily with Lewis bases. In the case of 4,4′‐bipyridine, an air‐sensitive coordination polymer is obtained. Characterization of this material by solid‐state NMR and EPR spectroscopy reveals the presence of a charge‐transfer polymer, which forms as a function of intramolecular Ni→4,4′‐bpy electron transfer (ET), providing an array of oxidized nickel sites and reduced 4,4′‐bpy radical anion sites. Notably, the related intermolecular reaction between the model fragments [Ni(dnppe)2] (dnppe=1,2‐bis(di‐n‐propylphosphino)ethane) and a bis(boraneyl)‐protected 4,4′‐bpy, provides no ET. Overall, the P2BCy4 fragment provides a unique opportunity for Lewis base activation, in one case allowing for the facile construction of monomers for incorporation into redox‐active macromolecules.
The Xanthate Route to Indolines, Indoles, and their Aza Congeners
Authors: Zard Samir Z.
Published: April 2020

Convergent routes to a variety of indolines, indoles, oxindoles, and their aza analogues involving radical additions of xanthates are described. Three approaches are summarized. The first is the least general and relies on the generation of aryl or heteroaryl radicals starting from diazonium salts. The second involves radical addition to N‐allylanilines followed by ring‐closure onto the aromatic core. A large variety of indolines and azaindolines can thus be obtained and, in many cases, converted into the corresponding indoles and azaindoles by various methods. The synthesis of novel fluoroazaindolines and fluoroazaindoles by a rare homolytic ipso‐substitution of fluorine atoms is particularly noteworthy. The last approach hinges on the direct modification of indoles by radical addition to the pyrrole subunit of the indole nucleus. Application of this methodology to the total synthesis of melatonin and the alkaloids mersicarpine, caulerpine, and the pentacyclic skeleton of tronocarpine is briefly discussed. Most of the compounds described herein would be difficult to obtain by more traditional routes.
Discoveries and Challenges en Route to Swinhoeisterol A
Authors: Duecker Fenja L. , Heinze Robert C. , Steinhauer Simon , Heretsch Philipp
Published: April 2020

In this work, a full account of the authors’ synthetic studies is reported that culminated in the first synthesis of 13(14→8),14(8→7)diabeo‐steroid swinhoeisterol A as well as the related dankasterones A and B, 13(14→8)abeo‐steroids, and periconiastone A, a 13(14→8)abeo‐4,14‐cyclo‐steroid. Experiments are described in detail that provided further insight into the mechanism of the switchable radical framework reconstruction approach. By discussing failed strategies and tactics towards swinhoeisterol A, the successful route that also allowed an access to structurally closely related analogues, such as Δ22‐24‐epi‐swinhoeisterol A, is eventually presented.
A Resin‐Supported Formate Catalyst for the Transformative Reduction of Carbon Dioxide with Hydrosilanes
Authors: Pramudita Ria Ayu , Manaka Yuichi , Motokura Ken
Published: April 2020

A heterogeneous formate anion catalyst for the transformative reduction of carbon dioxide (CO2) based on a polystyrene and divinylbenzene copolymer modified with alkylammonium formate was prepared from a widely available anion exchange resin. The catalyst preparation was easy and the characterization was carried out by using elemental analysis, Fourier transform infrared (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), and solid‐state 13C cross‐polarization/magic‐angle spinning nuclear magnetic resonance (13C CP/MAS NMR) spectroscopy. The catalyst displayed good catalytic activity for the direct reduction of CO2 with hydrosilanes, tunably yielding silylformate or methoxysilane products depending on the hydrosilanes used. The catalyst was also active for the reductive insertion of CO2 into both primary and secondary amines. The catalytic activity of the resin‐supported formate can be predicted from the FTIR spectra of the catalyst, probably because of the difference in the ionic interaction strength between the supported alkylammonium cations and formate anions. The ion pair density is thought to influence the catalytic activity, as shown by the elemental and solid‐state 13C NMR analyses.
Organoboron Derivatives of Stereoregular Phenylcyclosilsesquioxanes
Authors: Anisimov Anton A. , Drozdov Fedor V. , Vysochinskaya Yulia S. , Minyaylo Ekaterina O. , Peregudov Alexander S. , Dolgushin Fedor M. , Shchegolikhina Olga I. , Muzafarov Aziz M.
Published: April 2020

This study presents the synthesis of organoboron derivatives of stereoregular 4‐, 6‐, and 12‐unit phenylcyclosilsesquioxanes. All compounds obtained were isolated in good yields (70–80 %) and were fully characterized by 1H, 13C, 29Si, 11B NMR, IR spectroscopy, HRMS ESI, and elemental microanalysis. The structure of the key modifier, obtained for the first time, 4‐(tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)phenyl) dimethylvinylsilane, was also confirmed by single‐crystal XRD.
Noncovalent Functionalization of Few‐Layered Antimonene with Fullerene Clusters and Photoinduced Charge Separation in the Composite
Authors: Umeyama Tomokazu , Ohara Tomoya , Tsutsui Yusuke , Nakano Shota , Seki Shu , Imahori Hiroshi
Published: April 2020

Few‐layered antimonene (FLSb) nanosheets were noncovalently functionalized with fullerene C60 clusters by quick addition of a poor solvent (i.e., acetonitrile) into a mixed dispersion of FLSb and C60 in a good solvent (i.e., toluene). In a flash‐photolysis time‐resolved microwave conductivity (FP‐TRMC) measurement, the FLSb‐C60 composite, (FLSb+C60)m, showed a rapid rise in transient conductivity, whereas no conductivity signal was observed in the single components, FLSb and C60. This demonstrated the occurrence of photoinduced charge separation between FLSb and C60 in (FLSb+C60)m. Furthermore, a photoelectrochemical device with an electrophoretically deposited (FLSb+C60)m film exhibited an enhanced efficiency of photocurrent generation, compared to those of the single‐components, FLSb and C60, due to the photoinduced charge separation between FLSb and C60. This work provides a promising approach for fabrication of antimonene–organic molecule composites and paves the way for their application in optoelectronics.
Modular Medical Imaging Agents Based on Azide–Alkyne Huisgen Cycloadditions: Synthesis and Pre‐Clinical Evaluation of 18F‐Labeled PSMA‐Tracers for Prostate Cancer Imaging
Authors: Böhmer Verena I. , Szymanski Wiktor , van den Berg Keimpe‐Oeds , Mulder Chantal , Kobauri Piermichele , Helbert Hugo , van der Born Dion , Reeβing Friederike , Huizing Anja , Klopstra Marten , Samplonius Douwe F. , Antunes Ines F. , Sijbesma Jürgen W. A. , Luurtsema Gert , Helfrich Wijnand , Visser Ton J. , Feringa Ben L. , Elsinga Philip H.
Published: April 2020

Since the seminal contribution of Rolf Huisgen to develop the [3+2] cycloaddition of 1,3‐dipolar compounds, its azide–alkyne variant has established itself as the key step in numerous organic syntheses and bioorthogonal processes in materials science and chemical biology. In the present study, the copper(I)‐catalyzed azide–alkyne cycloaddition was applied for the development of a modular molecular platform for medical imaging of the prostate‐specific membrane antigen (PSMA), using positron emission tomography. This process is shown from molecular design, through synthesis automation and in vitro studies, all the way to pre‐clinical in vivo evaluation of fluorine‐18‐ labeled PSMA‐targeting ‘F‐PSMA‐MIC’ radiotracers (t1/2=109.7 min). Pre‐clinical data indicate that the modular PSMA‐scaffold has similar binding affinity and imaging properties to the clinically used [68Ga]PSMA‐11. Furthermore, we demonstrated that targeting the arene‐binding in PSMA, facilitated through the [3+2]cycloaddition, can improve binding affinity, which was rationalized by molecular modeling. The here presented PSMA‐binding scaffold potentially facilitates easy coupling to other medical imaging moieties, enabling future developments of new modular imaging agents.
Evidence of Alpha Radiolysis in the Formation of a Californium Nitrate Complex
Authors: Galley Shane S. , Gaggioli Carlo Alberto , Zeller Matthias , Celis‐Barros Cristian , Albrecht‐Schmitt Thomas E. , Gagliardi Laura , Bart Suzanne C.
Published: April 2020

Well‐characterized complexes of transplutonium elements are scarce because of the experimental challenges of working with these elements and the rarity of the isotopes. This leads to a lack of structural and spectroscopic data needed to understand the nature of chemical bonds in these compounds. In this work, the synthesis of Cf(DOPOq)2(NO3)(py) (DOPOq=2,4,6,8‐tetra‐tert‐butyl‐1‐oxo‐1H‐phenoxazin‐9‐olate; py=pyridine) is reported, in which the nitrate anion is hypothesized to form through the α‐radiolysis‐induced reaction of pyridine and/or the ligand. Computational analysis of the electronic structure of the complex reveals that the CfIII–ligand interactions are largely ionic.
Iminodiacetic Acid as a Novel Metal‐Binding Pharmacophore for New Delhi Metallo‐β‐lactamase Inhibitor Development
Authors: Chen Allie Y. , Thomas Caitlyn A. , Thomas Pei W. , Yang Kundi , Cheng Zishuo , Fast Walter , Crowder Michael W. , Cohen Seth M.
Published: April 2020

The fungal natural product aspergillomarasmine A (AMA) has been identified as a noncompetitive inhibitor of New Delhi metallo‐β‐lactamase‐1 (NDM‐1) that inhibits by removing ZnII from the active‐site. The nonselective metal‐chelating properties and difficult synthesis and derivatization of AMA have hindered the development of this scaffold into a potent and selective inhibitor of NDM‐1. Iminodiacetic acid (IDA) has been identified as the metal‐binding pharmacophore (MBP) core of AMA that can be leveraged for inhibitor development. Herein, we report the use of IDA for fragment‐based drug discovery (FBDD) of NDM‐1 inhibitors. IDA (IC50=120 μM) was developed into inhibitor 23 f (IC50=8.6 μM, Ki=2.6 μM), which formed a ternary complex with NDM‐1, as evidenced by protein thermal‐shift and native‐state electrospray ionization mass spectrometry (ESI‐MS) experiments. Combining mechanistic analysis with inhibitor derivatization, the use of IDA as an alternative AMA scaffold for NDM‐1 inhibitor development is detailed.
Metastable Dianions and Dications
Authors: Quiñonero David , Alkorta Ibon , Elguero Jose
Published: April 2020

A theoretical study of metastable dianions and dications has been carried out at the CCSD(T)//MP2 level. MX32−and LX42−(M=Li and Na, L=Be and Mg, X=F and Cl) have been considered as dianions, M3X2+(M=Li and Na, X=F and Cl), YH32+and ZH42+(Y=F and Cl and Z=O, S) as dications. Minima structures are found in all cases, but they are less stable than the corresponding dissociated pair of mono‐ions. The dissociation profile of the molecules in two mono‐ions has been explored showing in all cases a maximum that prevent their spontaneous dissociation. The strength and nature of the chemical bond in the dianions and dications have been analyzed with the QTAIM, NBO and LMOEDA method and compared to the corresponding monoanions and monocations.
A New Conducting Copolymer Bearing Electro‐Active Nitroxide Groups as Organic Electrode Materials for Batteries
Authors: Assumma L. , Kervella Y. , Mouesca J.‐M. , Mendez M. , Maurel V. , Dubois L. , Gutel T. , Sadki S.
Published: April 2020

To reduce the amount of conducting additives generally required for polynitroxide‐based electrodes, a stable radical (TEMPO) is combined with a conductive copolymer backbone consisting of 2,7‐bisthiophene carbazole (2,7‐BTC), which is characterized by a high intrinsic electronic conductivity. This work deals with the synthesis of this new polymer functionalized by a redox nitroxide. Fine structural characterization using electron paramagnetic resonance (EPR) techniques established that: 1) the nitroxide radicals are properly attached to the radical chain (continuous wave EPR) and 2) the polymer chain has very rigid conformations leading to a set of well‐defined distances between first neighboring pairs of nitroxides (pulsed EPR). The redox group combined with the electroactive polymer showed not only a very high electrochemical reversibility but also a perfect match of redox potentials between the de‐/doping reaction of the bisthiophene carbazole backbone and the redox activity of the nitroxide radical. This new organic electrode shows a stable capacity (about 60 mAh g−1) and enables a strong reduction in the amount of carbon additive due to the conducting‐polymer skeleton.
TRPM6 and TRPM7: Novel players in cell intercalation during vertebrate embryonic development
Authors: Runnels Loren W. , Komiya Yuko
Published: April 2020

A common theme in organogenesis is how the final structure of organs emerge from epithelial tube structures, with the formation of the neural tube being one of the best examples. Two types of cell movements co‐occur during neural tube closure involving the migration of cells toward the midline of the embryo (mediolateral intercalation or convergent extension) as well as the deep movement of cells from inside the embryo to the outside of the lateral side of the neural plate (radial intercalation). Failure of either type of cell movement will prevent neural tube closure, which can produce a range of neural tube defects (NTDs), a common congenital disease in humans. Numerous studies have identified signaling pathways that regulate mediolateral intercalation during neural tube closure. Less understood are the pathways that govern radial intercalation. Using the Xenopus laevis system, our group reported the identification of transient receptor potential (TRP) channels, TRPM6 and TRPM7, and the Mg2+ ion they conduct, as novel and key factors regulating both mediolateral and radial intercalation during neural tube closure. Here we broadly discuss tubulogenesis and cell intercalation from the perspective of neural tube closure and the respective roles of TRPM7 and TRPM6 in this critical embryonic process.
Self‐organizing cicada choruses respond to the local sound and light environment
Authors: Sheppard Lawrence W. , Mechtley Brandon , Walter Jonathan A. , Reuman Daniel C.
Published: April 2020

Periodical cicadas exhibit an extraordinary capacity for self‐organizing spatially synchronous breeding behavior. The regular emergence of periodical cicada broods across the United States is a phenomenon of longstanding public and scientific interest, as the cicadas of each brood emerge in huge numbers and briefly dominate their ecosystem. During the emergence, the 17‐year periodical cicada species Magicicada cassini is found to form synchronized choruses, and we investigated their chorusing behavior from the standpoint of spatial synchrony.

Cicada choruses were observed to form in trees, calling regularly every five seconds. In order to determine the limits of this self‐organizing behavior, we set out to quantify the spatial synchronization between cicada call choruses in different trees, and how and why this varies in space and time.

We performed 20 simultaneous recordings in Clinton State Park, Kansas, in June 2015 (Brood IV), with a team of citizen‐science volunteers using consumer equipment (smartphones). We use a wavelet approach to show in detail how spatially synchronous, self‐organized chorusing varies across the forest.

We show how conditions that increase the strength of audio interactions between cicadas also increase the spatial synchrony of their chorusing. Higher forest canopy light levels increase cicada activity, corresponding to faster and higher‐amplitude chorus cycling and to greater synchrony of cycles across space. We implemented a relaxation‐oscillator‐ensemble model of interacting cicadas, finding that a tendency to call more often, driven by light levels, results in all these effects.

Results demonstrate how the capacity to self‐organize in ecology depends sensitively on environmental conditions. Spatially correlated modulation of cycling rate by an external driver can also promote self‐organization of phase synchrony.