bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Phase Stability in CsPbI3 Enabled by Pb–I Octahedra Anchors for Efficient Inorganic Perovskite Photovoltaics
Authors: Wang Yong , Chen Gaoyuan , Ouyang Dan , He Xinjun , Li Can , Ma Ruiman , Yin Wan‐Jian , Choy Wallace C. H. 
Published: May 2020

AbstractCsPbI3 inorganic perovskite has exhibited some special properties particularly crystal structure distortion and quantum confinement effect, yet the poor phase stability of CsPbI3 severely hinders its applications. Herein, the nature of the photoactive CsPbI3 phase transition from the perspective of PbI6 octahedra is revealed. A facile method is also developed to stabilize the photoactive phase and to reduce the defect density of CsPbI3. CsPbI3 is decorated with multifunctional 4‐aminobenzoic acid (ABA), and steric neostigmine bromide (NGBr) is subsequently used to further mediate the thin films' surface (NGBr‐CsPbI3(ABA)). The ABA or NG cation adsorbed onto the grain boundaries/surface of CsPbI3 anchors the PbI6 octahedra via increasing the energy barriers of octahedral rotation, which maintains the continuous array of corner‐sharing PbI6 octahedra and kinetically stabilizes the photoactive phase CsPbI3. Moreover, the added ABA and NGBr not only interact with shallow‐ or deep‐level defects in CsPbI3 to significantly reduce defect density, but also lead to improved energy‐level alignment at the interfaces between the CsPbI3 and the charge transport layers. Finally, the champion NGBr‐CsPbI3(ABA)‐based inorganic perovskite solar cell delivers 18.27% efficiency with excellent stability. Overall, this work demonstrates a promising concept to achieve highly phase‐stabilized inorganic perovskite with suppressed defect density for promoting its optoelectronic applications.
Direct Evidence of Graphene‐Induced Molecular Reorientation in Polymer Films
Authors: Carr Amanda J. , Head Ashley , Boscoboinik Jorge Anibal , Bhatia Surita R. , Eisaman Matthew D. 
Published: May 2020

AbstractFor the first time, direct evidence of graphene‐induced molecular reorientation in polymer films using polarization modulated infrared reflection absorption spectroscopy (PM‐IRRAS) is presented. By creating favorable electrostatic interactions, graphene–polymer interfaces can be controlled by varying polymer and solvent composition. After transfer of unmodified graphene from copper onto a polymer substrate, polymer chain rearrangement relative to the orientation at the polymer‐copper interfaces is observed using PM‐IRRAS. Transfer success is characterized using both optical transmission measurements and Raman spectroscopy to quantify the transfer fidelity, that is, graphene coverage fraction. Taken together, oxygen‐containing poly(ethylene‐co‐vinyl acetate) shows more polymer chain rearrangement and better graphene coverage compared to oxygen‐free polyethylene. Polymer composition seems to dominate graphene–polymer interactions while solvent choice has a smaller effect on transfer quality. These results are the first direct measurement of this effect and point toward the possibility of engineering graphene–polymer interactions for specific applications.
Ion‐Selective Sensors Based on Laser‐Induced Graphene for Evaluating Human Hydration Levels Using Urine Samples
Authors: Kucherenko Ivan S. , Sanborn Delaney , Chen Bolin , Garland Nate , Serhan Michael , Forzani Erica , Gomes Carmen , Claussen Jonathan C. 
Published: May 2020

AbstractComplex graphene electrode fabrication protocols including conventional chemical vapor deposition and graphene transfer techniques as well as more recent solution‐phase printing and postprint annealing methods have hindered the wide‐scale implementation of electrochemical devices including solid‐state ion‐selective electrodes (ISEs). Herein, a facile graphene ISE fabrication technique that utilizes laser induced graphene (LIG), formed by converting polyimide into graphene by a CO2 laser and functionalization with ammonium ion (NH4+) and potassium ion (K+) ion‐selective membranes, is demonstrated. The electrochemical LIG ISEs exhibit a wide sensing range (0.1 × 10−3–150 × 10−3 m for NH4+ and 0.3 × 10−3–150 × 10−3 m for K+) with high stability (minimal drop in signal after 3 months of storage) across a wide pH range (3.5–9.0). The LIG ISEs are also able to monitor the concentrations of NH4+ and K+ in urine samples (29–51% and 17–61% increase for the younger and older patient; respectively, after dehydration induction), which correlate well with conventional hydration status measurements. Hence, these results demonstrate a facile method to perform in‐field ion sensing and are the first steps in creating a protocol for quantifying hydration levels through urine testing in human subjects.
Wearable Devices Using Nanoparticle Chains as Universal Building Blocks with Simple Filtration‐Based Fabrication and Quantum Sensing
Authors: Fan Hua , Maheshwari Vivek 
Published: May 2020

AbstractSelf‐assembled micrometer long gold nanoparticle chains are used as building block to fabricate a range of flexible devices to monitor human physiological signals by an easy filtration method. The chains serve as the base material for all the devices and their interconnects and contact pads as well. The micrometer long chains are an array of nanoparticles with gaps of 1–2 nm between adjacent particles. The gaps serve as quantum tunneling barrier and their modulation is basis of signal sensing in these devices. Deposited on a flexible membrane, the chains monitor temperature, artery pulsation, and electrocardiograms (ECG) signals with ease. This simple method provides an avenue to fabricate low cost integrated wearable devices based on quantum phenomena.
External Stimuli Responsive Bis(anthryl)borylaniline AIEgens for Viscosity and Temperature Sensing: The Game of Molecular Flexibility
Authors: Pandey Umesh Pratap , Thilagar Pakkirisamy 
Published: May 2020

AbstractExternal stimuli‐responsive luminogens have attracted a lot of attention in the recent years owing to their potential applications in various fields such as sensing, bio‐probes, and optical devices. In this work, the design and synthesis of a new class of external stimuli‐responsive anthracene based fluorescent bis‐(anthryl)boryl anilines 1 and 2 are disclosed. The electronic and optical properties of these compounds are fine‐tuned by varying the amine donor strength. Using steady‐state and time‐resolved photoluminescnece studies in both solution and condensed state together with computational studies (both ground and excited state), it is established that both 1 and 2 exhibit molecular motion dependent emission characteristics. Owing to their molecular conformational flexibility and inherent charge transfer characteristics, 1 and 2 show intriguing optical features such as aggregation induced emission enhancement, viscochromism, temperature sensing, and mechanoluminescence as compared to structurally rigid tris(9‐anthryl)boron without amine donor moieties. These unique properties of 1 and 2 are utilized for detecting local viscosity and temperature sensing over a wide range from 190–300 K. Compound 2 emits pure white light ((Commission internationale de l'éclairage) CIE 0.33, 0.33) at 250 K.
Compact Optical Polarization‐Insensitive Zoom Metalens Doublet
Authors: Wei Yunxuan , Wang Yuxi , Feng Xing , Xiao Shunyuan , Wang Zhaokun , Hu Tie , Hu Manchen , Song Jinwen , Wegener Martin , Zhao Ming , Xia Jinsong , Yang Zhenyu 
Published: May 2020

AbstractMetasurface‐based lenses (metalenses) offer specific conceptual advantages compared to ordinary refractive lenses. For example, it is possible to tune the focal length of a metalens doublet by varying the relative angle between the two metalenses while fixing their distance, leading to an extremely compact zoom lens. An improved polarization‐insensitive design based on silicon nanocylinders on silica substrates is presented. This design is realized and characterized experimentally at 1550 nm wavelength. By varying the relative angle between the metalenses in steps of 10°, tuning of the doublet focal length is demonstrated from −54 mm to ±3 mm to +54 mm. This results in a zoom factor of an imaging system varying between 1 and 18. For positive focal lengths, the doublet focusing efficiency has a minimum of 34% and a maximum of 83%. Experiment and theory are in very good agreement.
Versatile Cross‐Polarization Conversion Chiral Metasurface for Linear and Circular Polarizations
Authors: Fei Peng , Vandenbosch Guy A. E. , Guo Weihua , Wen Xin , Xiong Di , Hu Wei , Zheng Qi , Chen Xing 
Published: May 2020

AbstractIn this work, first the necessary conditions for a versatile cross‐polarization conversion meta‐atom that operates both for linear and circular cross polarizations are discussed. Based on these, a versatile chiral metasurface cross‐polarization converter is proposed. The correspondence between its physical geometry and polarization domain characteristics is studied. To verify the design concept, a prototype is fabricated and measured. An effective vertical and horizontal linear cross‐polarization conversion is achieved from 29.3 to 38.8 GHz (27.90%) and from 34.0 to 36.6 GHz (7.36%), respectively. Furthermore, the proposed converter also achieves circular polarization handedness rotation from 34.5 to 36.6 GHz (5.91%).
Enhanced Operational Stability of Perovskite Light‐Emitting Electrochemical Cells Leveraging Ionic Additives
Authors: Mishra Aditya , Alahbakhshi Masoud , Haroldson Ross , Bastatas Lyndon D. , Gu Qing , Zakhidov Anvar A. , Slinker Jason D. 
Published: May 2020

AbstractHybrid perovskites are emerging as highly efficient materials for optoelectronic applications, however, their operational lifetime has remained a limiting factor for their continued progress. In this work, perovskite light emitting electrochemical cells utilizing an optimized fraction of lithium hexafluorophosphate (LiPF6) salt additive exhibit enhanced stability. At 0.5 wt% LiPF6, devices exhibit 100 h operation at high brightness in excess of 800 cd m−2 under constant current driving, achieving a maximum luminance of 3260 cd m−2 and power efficiency of 9.1 Lm W−1. This performance extrapolates to a 6700 h luminance half‐life from 100 cd m−2, a 5.6‐fold improvement over devices with no LiPF6. Analysis under constant voltage driving reveals three current regimes, with lithium addition strongly enhancing current in the second and third regimes. The third regime correlates lower rates of luminance with lowered current flow. These losses are mitigated by LiPF6 addition, an effect postulated to arise from preservation of perovskite structure. Electrochemical impedance spectroscopy with equivalent circuit modeling reveals that electrical double layer widths are minimized at 0.5 wt% LiPF6 and inversely correlated with efficient performance. These results demonstrate that an optimal LiPF6 concentration improves stability and efficiency through improved double layer formation and retention of perovskite structure.
Long‐Lived Efficient Inverted Organic Light‐Emitting Diodes Developed by Controlling Carrier Injection Barrier into Emitting Layer
Authors: Fukagawa Hirohiko , Ito Hirokazu , Kawamura Shizuka , Iwasaki Yukiko , Inagaki Kaito , Oono Taku , Sasaki Tsubasa , Shimizu Takahisa 
Published: May 2020

AbstractInverted organic light‐emitting diodes (iOLEDs), where electrons are injected without the use of reactive metals such as alkali metals, have attracted extensive attention owing to their higher air stability than conventional OLEDs (cOLEDs). Although iOLEDs are promising for use in applications such as flexible displays, little is known about the emitting layer most suitable for improving their operational lifetime, which is one of the most important parameters for practical applications. Here, it is shown that the operational lifetimes of both iOLEDs and cOLEDs strongly depend on the hole and electron injection barriers of the emitting layer, which is clarified by synthesizing novel emitting hosts having similar molecular structures but different energy levels. The cOLED employing the novel emitting host with the largest hole injection barrier exhibits the shortest operational lifetime, whereas the iOLED employing the same emitting host exhibits the longest operational lifetime owing to the smallest electron injection barrier. The appropriate energy levels of the emitting layer can differ between iOLEDs and cOLEDs since the management conditions of the carriers, excitons, and polarons in iOLEDs are different from those in cOLEDs. A green iOLED with performance equivalent to that of state‐of‐the‐art green cOLEDs reported in the literature is first realized.
Distribution of Market Facilitation Program Payments and their Financial Impact for Illinois, Kansas, and Minnesota Farms
Authors: Paulson Nicholas D. , Featherstone Allen M. , Hadrich Joleen C. 
Published: May 2020

AbstractThe recent infusion of cash into production agriculture due to damages from retaliatory trade actions has been large. Up to $28 billion has been authorized through the Trade Mitigation Program in 2018 and 2019, accounting for a significant share of farm income and providing liquidity in an extended period of low prices. Using farm‐level data from Illinois, Kansas, and Minnesota, this research examines the importance of market facilitation program payments in supporting incomes and reducing credit default risk. Results illustrate the additional liquidity provided for farms, and the distributional effects across states and among farms within each state.
Comparison of Active Learning Techniques: Audience Response Questions Versus Small Group Discussion on Immediate‐ and Long‐term Knowledge Gain
Authors: Jordan Jaime , Missaghi Babak , Douglass Amy , Tolles Juliana 
Published: May 2020

AbstractObjectivesActive learning techniques help with motivation, involvement, and retention during didactics. There are few studies comparing different active learning methods, and these have yielded mixed results. The objective of this study was to compare the effect of two active learning methods—small‐group discussion and audience response system (ARS)—on immediate‐ and long‐term knowledge gain.MethodsThis was a prospective experimental study of emergency medicine (EM) subinterns and residents. Participants were randomized into two groups, and baseline knowledge was assessed with a multiple‐choice pretest. Didactic sessions on salicylate toxicity and ocular trauma were given to both groups utilizing either small‐group discussion or ARS. A crossover design was utilized to ensure that both groups received instruction by each method. A multiple‐choice posttest was administered following the didactics and again 2 months later. Pre‐ and posttests were identical. All test items were written by an academic faculty member with advanced training in medical education and item writing and were based on the goals and objectives of the session. Test items were piloted with a reference group of learners. Didactic instructors were blinded to test items. Data were analyzed using a linear mixed‐effects model.ResultsThirty‐eight subinterns and residents participated in the study. Both instructional methods showed immediate‐ and long‐term knowledge gain. The linear mixed‐effects model did not demonstrate any significant difference between instructional methods on immediate knowledge gain (mean difference = 0.18, p = 0.62, 95% confidence interval [CI] = −0.52 to 0.88) or long‐term knowledge gain (mean difference = −0.42, p = 0.36, 95% CI = −1.32 to 0.47).ConclusionIn this small study, there was no significant difference between instructional methods on immediate‐ and long‐term knowledge gain in EM subinterns and residents.
Discrete element method study on hopper discharge behaviors of binary mixtures of nonspherical particles
Authors: Zhao Ya , Chew Jia Wei 
Published: May 2020

AbstractThis study is aimed at unveiling the influence of binary mixtures of nonspherical particles on hopper discharge behavior, which remains poorly understood. The discrete element method (DEM) is employed to simulate seven particle types with aspect ratios between 0 and 2 (namely, a sphere, two ellipsoids, two cylinders, and two cuboids) with the same volume. Seven monodisperse systems and twelve binary‐shape mixtures are assessed. For the monodisperse systems, particle shape is the dominant factor dictating discharge rate, compared to other factors like aspect ratio, preferential orientation, and packing. Regarding the binary‐shape mixtures, the discharge rates are similar for all twelve mixtures, reflecting a surprising lack of shape effects, which in turn means the negligible impact of solid volume fraction, aspect ratio, and segregation extent. Moreover, collision force is generally negatively correlated with discharge rate.
Kβ X‐Ray Emission Spectroscopic Study of a Second‐Row Transition Metal (Mo) and Its Application to Nitrogenase‐Related Model Complexes
Authors: Castillo Rebeca G. , Henthorn Justin T. , McGale Jeremy , Maganas Dimitrios , DeBeer Serena 
Published: May 2020

AbstractIn recent years, X‐ray emission spectroscopy (XES) in the Kβ (3p‐1s) and valence‐to‐core (valence‐1s) regions has been increasingly used to study metal active sites in (bio)inorganic chemistry and catalysis, providing information about the metal spin state, oxidation state and the identity of coordinated ligands. However, to date this technique has been limited almost exclusively to first‐row transition metals. In this work, we present an extension of Kβ XES (in both the 4p‐1s and valence‐to‐1s [or VtC] regions) to the second transition row by performing a detailed experimental and theoretical analysis of the molybdenum emission lines. It is demonstrated in this work that Kβ2 lines are dominated by spin state effects, while VtC XES of a 4d transition metal provides access to metal oxidation state and ligand identity. An extension of Mo Kβ XES to nitrogenase‐relevant model complexes shows that the method is sufficiently sensitive to act as a spectator probe for redox events that are localized at the Fe atoms. Mo VtC XES thus has promise for future applications to nitrogenase, as well as a range of other Mo‐containing biological cofactors. Further, the clear assignment of the origins of Mo VtC XES features opens up the possibility of applying this method to a wide range of second‐row transition metals, thus providing chemists with a site‐specific tool for the elucidation of 4d transition metal electronic structure.
Independent Generation and Time‐Resolved Detection of 2′‐Deoxyguanosin‐N2‐yl Radicals
Authors: Zheng Liwei , Dai Xiaojuan , Su Hongmei , Greenberg Marc M. 
Published: May 2020

AbstractGuanine radicals are important reactive intermediates in DNA damage. Hydroxyl radical (HO.) has long been believed to react with 2′‐deoxyguanosine (dG) generating 2′‐deoxyguanosin‐N1‐yl radical (dG(N1‐H).) via addition to the nucleobase π‐system and subsequent dehydration. This basic tenet was challenged by an alternative mechanism, in which the major reaction of HO. with dG was proposed to involve hydrogen atom abstraction from the N2‐amine. The 2′‐deoxyguanosin‐N2‐yl radical (dG(N2‐H).) formed was proposed to rapidly tautomerize to dG(N1‐H).. We report the first independent generation of dG(N2‐H). in high yield via photolysis of 1. dG(N2‐H). is directly observed upon nanosecond laser flash photolysis (LFP) of 1. The absorption spectrum of dG(N2‐H). is corroborated by DFT studies, and anti‐ and syn‐dG(N2‐H). are resolved for the first time. The LFP experiments showed no evidence for tautomerization of dG(N2‐H). to dG(N1‐H). within hundreds of microseconds. This observation suggests that the generation of dG(N1‐H). via dG(N2‐H). following hydrogen atom abstraction from dG is unlikely to be a major pathway when HO. reacts with dG.
Highly Selective Removal of Perfluorinated Contaminants by Adsorption on All‐Silica Zeolite Beta
Authors: Van den Bergh Matthias , Krajnc Andraž , Voorspoels Stefan , Tavares Sergio Rodrigues , Mullens Steven , Beurroies Isabelle , Maurin Guillaume , Mali Gregor , De Vos Dirk E. 
Published: May 2020

AbstractPerfluorinated alkylated substances (PFASs) are widely used in industrial and commercial applications, leading to a widespread occurrence of these persistent and harmful contaminants in our environment. Removal of these compounds from surface and waste waters is being mandated by European and U.S. governments. Currently, there are no treatment techniques available that lower the concentrations of these compounds for large water bodies in a cost‐ and energy‐efficient way. We hereby propose a hydrophobic, all‐silica zeolite Beta material that is a highly selective and high‐capacity adsorbent for PFASs, even in the presence of organic competitors. Advanced characterization data demonstrate that the adsorption process is driven by a very negative adsorption enthalpy and favorable steric factors.
Biosynthesis of Biscognienyne B Involving a Cytochrome P450‐Dependent Alkynylation
Authors: Lv Jian‐Ming , Gao Yao‐Hui , Zhao Huan , Awakawa Takayoshi , Liu Ling , Chen Guo‐Dong , Yao Xin‐Sheng , Hu Dan , Abe Ikuro , Gao Hao 
Published: May 2020

AbstractThe alkyne is a biologically significant moiety found in many natural products and a versatile functional group widely used in modern chemistry. Recent studies have revealed the biosynthesis of acetylenic bonds in fatty acids and amino acids. However, the molecular basis for the alkynyl moiety in acetylenic prenyl chains occurring in a number of meroterpenoids remains obscure. Here, we identify the biosynthetic gene cluster and characterize the biosynthetic pathway of an acetylenic meroterpenoid biscognienyne B based on heterologous expression, feeding experiments, and in vitro assay. This work shows that the alkyne moiety is constructed by an unprecedented cytochrome P450 enzyme BisI, which shows promiscuous activity towards C5 and C15 prenyl chains. This finding provides an opportunity for discovery of new compounds, featuring acetylenic prenyl chains, through genome mining, and it also expands the enzyme inventory for de novo biosynthesis of alkynes.
Long‐term seagrass degradation: Integrating landscape, demographic, and genetic responses
Authors: Manent Pablo , Bañolas Gonzalo , Alberto Filipe , Curbelo Leticia , Espino Fernando , Tuya Fernando 
Published: May 2020

Abstract

Seagrass meadows are crucial habitats on nearshore areas, which are exposed to human disturbances that frequently cause seagrass loss. Although demographic and mapping data have been widely used in long‐term monitoring programmes, the integration of multi‐locus genotype data through time remains rare.
The present work links, for the first time, landscape, demographic, and genetic data for a seagrass, so as to explore long‐term responses to persistent human impacts. The temporal patterns in meadow area, shoot density, and clonal and genetic diversity of three Cymodocea nodosa meadows were compared: in one meadow directly affected by the construction of an industrial port and in two control areas. The hypothesis tested was that seagrass deterioration and subsequent habitat loss at the affected meadow would be associated with a reduction of seagrass clonal and genetic diversity.
The results show significant reductions in both meadow area (from approx. 21 to 1.5 ha) and shoot density (from approx. 1,800 to 400 shoots per m2) at the impacted meadow, with concurrently reduced clonal and allelic richness (by approx. 22%), as well as heterozygosity (HLmean, approx. 21%; Hobs, approx. 12%). These descriptors, however, remained stable, or even increased, in the controls.
Importantly for seagrass management, multi‐disciplinary analysis made it possible to link slower, large‐scale, landscape and genetic degradation processes with faster demographic deterioration on an intermediate meadow scale. Multi‐locus genotype data were also crucial for revealing long‐term degradation processes at the genetic level, which is undetectable by traditional monitoring techniques.
In summary, this holistic approach provides a valuable framework for long‐term seagrass monitoring programmes to detect cumulative signals of seagrass meadow degradation across a range of scales.