bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractEfficient 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

AbstractInternal 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

AbstractThe 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

PremiseSeed 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 ResultsIn 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.ConclusionsA 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

PremiseIn 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.MethodsMeasurements 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.ResultsAll 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.DiscussionResearchers 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

AbstractDiet 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

AbstractDer 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

AbstractClinical 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

AbstractOutreach 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

AbstractBackgroundPerspectives 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.MethodsA 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.ResultsCT 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.ConclusionCT 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

AbstractCarbon‐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

AbstractNovel 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

AbstractFast 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

AbstractFragment‐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

AbstractDirect 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

AbstractHerein, 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.