bluuebunny/crossref_metadata_2025 huggingface dataset:
ViSiElse: an innovative R-package to visualize raw behavioral data over time
Authors: Garnier Elodie M. , Fouret Nastasia , Descoins Médéric
Published: February 2020

The scientific community encourages the use of raw data graphs to improve the reliability and transparency of the results presented in articles. However, the current methods used to visualize raw data are limited to one or two numerical variables per graph and/or small sample sizes. In the behavioral sciences, numerous variables must be plotted together in order to gain insight into the behavior in question. In this article, we present ViSiElse, an R-package offering a new approach in the visualization of raw data. ViSiElse was developed with the open-source software R to visualize behavioral observations over time based on raw time data extracted from visually recorded sessions of experimental observations. ViSiElse gives a global overview of a process by creating a visualization of the timestamps for multiple actions and all participants into a single graph; individual or group behavior can then be easily assessed. Additional features allow users to further inspect their data by including summary statistics and time constraints.
Larger contactor area increases low-frequency vibratory sensitivity in hairy skin
Authors: Schmidt Daniel , Schlee Guenther , Germano Andresa M.C. , Milani Thomas L.
Published: February 2020

Background

In research, assessing vibratory cutaneous sensitivity is an important research branch to quantify various diseases or to develop devices for pattern recognition. The measured vibration perception thresholds (VPTs), however, are subjective and usually result in a large data variability. This might induce difficulties to detect differences, for example, when comparing different anatomical locations. Hence, a higher ability to detect changes is desirable. Another feature of VPTs is spatial summation, but in the literature it is controversially discussed whether or not this phenomenon is also present in the lower frequency range. For these reasons, the present study aimed to investigate whether an enlarged matrix contactor area (measured at the hairy skin) induces improvements in subjective sensitivity using high and low frequencies, and whether a large contactor area is better able to identify changes of VPTs than a small contactor area of a single contactor. For each frequency, we hypothesized an increased sensitivity for the matrix compared to the single contactor. We also hypothesized that changes can be better-detected between the anatomical locations when using the matrix than the single contactor.

Methods

Twenty healthy and young participants voluntarily took part in this study. Three anatomical locations at the torso were measured at the middle aspect of the lower back, middle lateral aspect of the upper arm, and the region just below the armpit. At each location, two frequencies (30, 200 Hz) and two contactor conditions (single contactor: 0.48 cm2 , contactor matrix: 9 × 0.48 cm2 = 4.32 cm2) were tested in a randomized order.

Results

Supporting our hypothesis, we found that improved cutaneous sensitivity after increasing the contactor size occurs not only at high, but also at low frequencies at all anatomical locations. Large contactor sizes resulted in higher sensitivity and in a superior ability to detect changes. The superior behavior of the matrix to exhibit a lower variability could not always be proven. This work may be relevant for future studies aiming to identify changes of VPTs in various patient groups, for example.
Enhanced Welfare through Market Integration: A Study of Growth, Variation and Price Integration of Chickpea
Authors: Wahlang L. , Sekhon M. K. , Kumar Sunny
Published: February 2020

Chickpea is the most important pulse in India. The present study is based on secondary data, worked out trends in production, seasonal variation and integration among major markets of India. Advance Econometrics analysis like Granger Causality test, Johansen Co-integration test and Vector Error Correction model were employed to examine the integration of markets. The trend in area and production shows fluctuations in major producing states except in Uttar Pradesh. In all the major producing states of chickpea, contribution of area was higher in production. The production trend improves in case of Madhya Pradesh whereas decreased in Rajasthan and Uttar Pradesh. Seasonality in arrivals has impacted the monthly retail price in all the selected markets. Out of six selected markets, five markets were having a long run price relationship. However, market integration has not yet reached an optimal level because all markets were not spatially integrated with one another in all the cases. The short run results indicated that chickpea’s markets were not well integrated. This could be due to poor market intelligence and unfavorable location of the markets. The policy intervention calls for strengthening market intelligent wing in all markets along with the establishing of online marketing system through computerization and networking. Strengthening of market infrastructure including transportation and communication facilities are the need of time in order to fully integrate the market prices. Concentration of marketing during the lean seasons helps reducing the impact of seasonality.
Oct motif variants in Beckwith–Wiedemann syndrome patients disrupt maintenance of the hypomethylated state of the H19/IGF2 imprinting control region
Authors: Kubo Shuichi , Murata Chihiro , Okamura Hanayo , Sakasegawa Taku , Sakurai Chiye , Hatsuzawa Kiyotaka , Hori Naohiro
Published: February 2020

The methylation status of imprinting control center 1 (IC1) regulates the monoallelic transcription of H19 and Igf2 in mammalian cells. Several single nucleotide variants in Oct motifs within IC1 occur in patients with Beckwith–Wiedemann syndrome (BWS) who have hypermethylated maternal IC1. However, the importance of Oct motifs in the regulation of IC1 methylation status remains unclear. Here, we demonstrate that three variants found in BWS (BWS variants) suppress intensive induction of DNA demethylation, whereas consensus disruption of motifs unrelated to BWS only slightly affects the induction of demethylation. BWS variants reduce DNA demethylation levels and trigger the accumulation of DNA methylation downstream of the IC1 transgenes. Thus, the risk of IC1 hypermethylation is associated with inhibitory levels of Oct motif‐dependent hypomethylation maintenance activities.
Scalable Synthesis of Ti3C2Tx MXene
Authors: Shuck Christopher E. , Sarycheva Asia , Anayee Mark , Levitt Ariana , Zhu Yuanzhe , Uzun Simge , Balitskiy Vitaliy , Zahorodna Veronika , Gogotsi Oleksiy , Gogotsi Yury
Published: February 2020

Scaling the production of synthetic 2D materials to industrial quantities has faced significant challenges due to synthesis bottlenecks whereby few have been produced in large volumes. These challenges typically stem from bottom‐up approaches limiting the production to the substrate size or precursor availability for chemical synthesis and/or exfoliation. In contrast, MXenes, a large class of 2D transition metal carbides and/or nitrides, are produced via a top‐down synthesis approach. The selective wet etching process does not have similar synthesis constraints as some other 2D materials. The reaction occurs in the whole volume; therefore, the process can be readily scaled with reactor volume. Herein, the synthesis of 2D titanium carbide MXene (Ti3C2Tx) is studied in two batch sizes, 1 and 50 g, to determine if large‐volume synthesis affects the resultant structure or composition of MXene flakes. Characterization of the morphology and properties of the produced MXene using scanning electron microscopy, X‐ray diffraction, dynamic light scattering, Raman spectroscopy, X‐ray photoelectron spectroscopy, UV–visible spectroscopy, and conductivity measurements show that the materials produced in both batch sizes are essentially identical. This illustrates that MXenes experience no change in structure or properties when scaling synthesis, making them viable for further scale‐up and commercialization.
Highly Stretchable Bilayer Lattice Structures That Elongate via In‐Plane Deformation
Authors: Yiming Burebi , Wu Lei , Zhang Mingqi , Han Zilong , Zhao Pei , Li Tiefeng , Jia Zheng , Qu Shaoxing
Published: February 2020

Many emerging technologies such as wearable batteries and electronics require stretchable functional structures made from intrinsically less deformable materials. The stretch capability of most demonstrated stretchable structures often relies on either initially out‐of‐plane configurations or the out‐of‐plane deflection of planar patterns. Such nonplanar features may dramatically increase the surface roughness, cause poor adhesion and adverse effects on subsequent multilayer processing, thereby posing a great challenge for flexible devices that require smooth surfaces (e.g., transparent electrodes in which flat‐surface‐enabled high optical transmittance is preferred). Inspired by the lamellar layouts of collagenous tissues, this work demonstrates a planar bilayer lattice structure, which can elongate substantially via only in‐plane motion and thus maintain a smooth surfaces. The constructed bilayer lattice exhibits a large stretchability up to 360%, far beyond the inherent deformability of the brittle constituent material and comparable to that of state‐of‐the‐art stretchable structures for flexible electronics. A stretchable conductor employing the bilayer lattice designs can remain electrically conductive at a strain of 300%, demonstrating the functionality and potential applications of the bilayer lattice structure. This design opens a new avenue for the development of stretchable structures that demand smooth surfaces.
Physically Adsorbed Metal Ions in Porous Supports as Electrocatalysts for Oxygen Evolution Reaction
Authors: Yang Liu , Liu Huibing , Shen Hangjia , Huang Yan , Wang Shitao , Zheng Lirong , Cao Dapeng
Published: February 2020

Developing highly efficient and earth‐abundant electrocatalysts for the oxygen evolution reaction (OER) is significantly important for water‐splitting. Here, for the first time it is reported that the physically adsorbed metal ions (PAMI) in porous materials can be served as highly efficient OER electrocatalysts, which provides a universal PAMI method to develop electrocatalysts. This PAMI method can be applied to almost all porous supports, including graphene, carbon nanotubes, C3N4, CaCO3, and porous organic polymers and all the systems exhibit excellent OER performance. In particular, the as‐synthesized Co0.7Fe0.3CB exhibits a small overpotential of 295 mV and 350 mV at the current density of 10 mA cm−2 and 100 mA cm−2, respectively, which exceeds commercial 40 wt% IrO2/CB and most reported non‐noble metal‐based OER catalysts. Moreover, the mass activity of Co0.7Fe0.3CB reaches 643.4 A g−1 at the overpotential of 320 mV, which is nearly 4.7 times higher than that of 40 wt% IrO2/CB. In addition, the advanced ex situ and in situ synchrotron X‐ray characterizations are carried out to unravel the PAMI synthetic process. In short, this PAMI method will break the conversional understanding, i.e., the most OER catalysts are synthesized chemically, because the new PAMI method does not require any chemical synthesis, which therefore opens a new avenue for the development of OER electrocatalysts.
Graphene/Strontium Titanate: Approaching Single Crystal–Like Charge Transport in Polycrystalline Oxide Perovskite Nanocomposites through Grain Boundary Engineering
Authors: Lin Yue , Dylla Maxwell Thomas , Kuo Jimmy Jiahong , Male James Patrick , Kinloch Ian Anthony , Freer Robert , Snyder Gerald Jeffery
Published: February 2020

Grain boundaries critically limit the electronic performance of oxide perovskites. These interfaces lower the carrier mobilities of polycrystalline materials by several orders of magnitude compared to single crystals. Despite extensive effort, improving the mobility of polycrystalline materials (to meet the performance of single crystals) is still a severe challenge. In this work, the grain boundary effect is eliminated in perovskite strontium titanate (STO) by incorporating graphene into the polycrystalline microstructure. An effective mass model provides strong evidence that polycrystalline graphene/strontium titanate (G/STO) nanocomposites approach single crystal‐like charge transport. This phenomenological model reduces the complexity of analyzing charge transport properties so that a quantitative comparison can be made between the nanocomposites and STO single crystals. In other related works, graphene composites also optimize the thermal transport properties of thermoelectric materials. Therefore, decorating grain boundaries with graphene appears to be a robust strategy to achieve “phonon glass–electron crystal” behavior in oxide perovskites.
Alloy Engineering in Few‐Layer Manganese Phosphorus Trichalcogenides for Surface‐Enhanced Raman Scattering
Authors: Hou Xiangyu , Zhang Xuyang , Ma Qingwei , Tang Xiao , Hao Qi , Cheng Yingchun , Qiu Teng
Published: February 2020

Manganese phosphorus trichalcogenides are widely used in the field of photocatalysis and magnetic studies due to their broadband gaps. Herein, an alloy engineering method for the few‐layer manganese phosphorus trichalcogenides (MnPS3–xSex, 0 ≤ x ≤ 3) in surface‐enhanced Raman scattering (SERS) is reported. A new strategy, with the coupling of exciton resonance (µex) and photoinduced charge transfer (PICT), is applied to screen out materials for SERS enhancement. According to the calculation of density functional theory, the bandgap of manganese phosphorus trichalcogenides (MnPS3) can be adjusted to match the band energy of Rhodamine 6G molecules by alloy engineering. Furthermore, a series of few‐layer MnPS3–xSex (0 ≤ x ≤ 3) are fabricated to study the PICT‐induced SERS behavior under resonance excitation. The good performance with a detection limit down to 10−9 m indicates that the synergistic resonances between µex and PICT are crucial to the enhancement.
Single‐Molecular White‐Light Emitters and Their Potential WOLED Applications
Authors: Chen Zhao , Ho Cheuk‐Lam , Wang Liqi , Wong Wai‐Yeung
Published: February 2020

White organic light‐emitting diodes (WOLEDs) are superior to traditional incandescent light bulbs and compact fluorescent lamps in terms of their merits in ensuring pure white‐light emission, low‐energy consumption, large‐area thin‐film fabrication, etc. Unfortunately, WOLEDs based on multilayered or multicomponent (red, green, and blue (RGB)) emissive layers can suffer from some remarkable disadvantages, such as intricate device fabrication and voltage‐dependent emission color, etc. Single molecules, which can emit white light, can be used to replace multiple emitters, leading to a simplified fabrication process, stable and reproducible WOLEDs. Recently, the performance of WOLEDs by using single molecules is catching up with that of the state‐of‐the‐art devices fabricated by multicomponent emitters. Therefore, an increasing attention has been paid on single white‐light‐emitting materials for efficient WOLEDs. In this review, different mechanisms of white‐light emission from a single molecule and the performance of single‐molecule‐based WOLEDs are collected and expounded, hoping to light up the interesting subject on single‐molecule white‐light‐emitting materials, which have great potential as white‐light emitters for illumination and lighting applications in the world.
Materials and Technologies to Combat Counterfeiting of Pharmaceuticals: Current and Future Problem Tackling
Authors: Zhang Heyang , Hua Dawei , Huang Chaobo , Samal Sangram Keshari , Xiong Ranhua , Sauvage Félix , Braeckmans Kevin , Remaut Katrien , De Smedt Stefaan C.
Published: February 2020

The globalization of drug trade leads to the expansion of pharmaceutical counterfeiting. The immense threat of low quality drugs to millions of patients is considered to be an under‐addressed global health challenge. Analytical authentication technologies are the most effective methods to identify active pharmaceutical ingredients and impurities. However, most of these analytical testing techniques are expensive and need skilled personnel. To combat counterfeiting of drugs, the package of an increasing number of drugs is being protected through advanced package labeling technologies. Though, package labeling is only effective if the drugs are not repackaged. Therefore “in‐drug labeling,” instead of “drug package labeling,” may become powerful tools to protect drugs. This review aims to overview how advanced micro‐ and nanomaterials might become interesting markers for the labeling of tablets and capsules. Clearly, how well such identifiers can be integrated into “solid drugs” without compromising drug safety and efficacy remains a challenge. Also, incorporation of tags has so far only been reported for the protection of solid drug dosage forms. No doubts that in‐drug labeling technologies for “liquid drugs,” like injectables which contain expensive peptides, monoclonal antibodies, vaccines, dermal fillers, could help to protect them from counterfeiting as well.
Supramolecular Chiral 2D Materials and Emerging Functions
Authors: Shen Bowen , Kim Yongju , Lee Myongsoo
Published: February 2020

Chiral materials are widely applied in various fields such as enantiomeric separation, asymmetric catalysis, and chiroptical effects, providing stereospecific conditions and environments. Supramolecular concepts to create the chiral materials can provide an insight for emerging chiro‐optical properties due to their well‐defined scaffolds and the precise functionalization of the surfaces or skeletons. Among the various supramolecular chiral structures, 2D chiral sheet structures are particularly interesting materials because of their extremely high surface area coupled with many unique chemical and physical properties, thereby offering potential for the next generation of functional materials for optically active systems and optoelectronic devices. Nevertheless, relatively limited examples for 2D chiral materials exhibiting specific functionality have been reported because incorporation of molecular chirality into 2D architectures is difficult at the present stage. Here, a brief overview of the recent advances is provided on the construction of chiral supramolecular 2D materials and their functions. The design principles toward 2D chirality and their potential applications are also discussed.
Understanding the Self‐Assembly of Cellulose Nanocrystals—Toward Chiral Photonic Materials
Authors: Tran Andy , Boott Charlotte E. , MacLachlan Mark J.
Published: February 2020

Over millions of years, animals and plants have evolved complex molecules and structures that endow them with vibrant colors. Among the sources of natural coloration, structural color is prominent in insects, bird feathers, snake skin, plants, and other organisms, where the color arises from the interaction of light with nanoscale features rather than absorption from a pigment. Cellulose nanocrystals (CNCs) are a biorenewable resource that spontaneously organize into chiral nematic liquid crystals having a hierarchical structure that resembles the Bouligand structure of arthropod shells. The periodic, chiral nematic organization of CNC films leads them to diffract light, making them appear iridescent. Over the past two decades, there have been many advances to develop the photonic properties of CNCs for applications ranging from cosmetics to sensors. Here, the origin of color in CNCs, the control of photonic properties of CNC films, the development of new composite materials of CNCs that can yield flexible photonic structures, and the future challenges in this field are discussed. In particular, recent efforts to make flexible photonic materials using CNCs are highlighted.
Thermal Effects on the Crystallization Kinetics, and Interfacial Adhesion of Single‐Crystal Phase‐Change Gallium
Authors: Yunusa Muhammad , Lahlou Aliénor , Sitti Metin
Published: February 2020

Although substrates play an important role upon crystallization of supercooled liquids, the influences of surface temperature and thermal property have remained elusive. Here, the crystallization of supercooled phase‐change gallium (Ga) on substrates with different thermal conductivity is studied. The effect of interfacial temperature on the crystallization kinetics, which dictates thermo‐mechanical stresses between the substrate and the crystallized Ga, is investigated. At an elevated surface temperature, close to the melting point of Ga, an extended single‐crystal growth of Ga on dielectric substrates due to layering effect and annealing is realized without the application of external fields. Adhesive strength at the interfaces depends on the thermal conductivity and initial surface temperature of the substrates. This insight can be applicable to other liquid metals for industrial applications, and sheds more light on phase‐change memory crystallization.
Surface Modification of a MXene by an Aminosilane Coupling Agent
Authors: Riazi Hossein , Anayee Mark , Hantanasirisakul Kanit , Shamsabadi Ahmad Arabi , Anasori Babak , Gogotsi Yury , Soroush Masoud
Published: February 2020

MXenes, two‐dimensional (2D) transition metal carbides and/or nitrides, possess surface termination groups such as hydroxyl, oxygen, and fluorine, which are available for surface functionalization. Their surface chemistry is critical in many applications. This article reports amine functionalization of Ti3C2Tx MXene surface with [3‐(2‐aminoethylamino)‐propyl]trimethoxysilane (AEAPTMS). Characterization techniques such as X‐ray photoelectron spectroscopy verify the success of the surface functionalization and confirm that the silane coupling agent bonds to Ti3C2Tx surface both physically and chemically. The functionalization changes the MXene surface charge from −35 to +25 mV at neutral pH, which allows for in situ preparation of self‐assembled films. Further, surface charge measurements of the functionalized MXene at different pH values show that the functionalized MXene has an isoelectric point at a pH around 10.7, and the highest reported positive surface charge of +62 mV at a pH of 2.58. Furthermore, the existence of a mixture of different orientations of AEAPTMS and the simultaneous presence of protonated and free amine groups on the surface of Ti3C2Tx are demonstrated. The availability of free amine groups on the surface potentially permits the fabrication of crosslinked electrically conductive MXene/epoxy composites, dye adsorbents, high‐performance membranes, and drug carriers. Surface modifications of this type are applicable to many other MXenes.
Collagenase‐Cleavable Peptide Amphiphile Micelles as a Novel Theranostic Strategy in Atherosclerosis
Authors: Chin Deborah D. , Poon Christopher , Trac Noah , Wang Jonathan , Cook Jackson , Joo Johan , Jiang Zhangjingyi , Sta Maria Naomi Sulit , Jacobs Russell E. , Chung Eun Ji
Published: February 2020

Atherosclerosis is an inflammatory disease characterized by plaques that can cause sudden myocardial infarction upon rupture. Such rupture‐prone plaques have thin fibrous caps due to collagenase degradation, and a noninvasive diagnostic tool and targeted therapy that can identify and treat vulnerable plaques and may inhibit the onset of acute cardiac events. Toward this goal, monocyte‐binding, collagenase‐inhibiting, and gadolinium‐modified peptide amphiphile micelles (MCG PAMs) are developed. Monocyte chemoattractant protein‐1 (MCP‐1) binds to C‐C chemokine receptor‐2 expressed on pathological cell types present within plaques. Through the peptide binding motif of MCP‐1, MCG PAMs bind to monocytes and vascular smooth muscle cells in vitro. Moreover, using magnetic resonance imaging, MCG PAMs show enhanced targeting and successful detection of plaques in diseased mice in vivo and act as contrast agents for molecular imaging. Through the collagenase‐cleaving peptide sequence of collagen [VPMS‐MRGG], MCG PAMs can compete for collagenases that degrade the fibrous cap of plaques, providing therapy. MCG PAM‐treated mice show increased fibrous cap thickness by 61% and 113% histologically compared to nontargeting micelle‐ or PBS‐treated mice (p = 0.0075 and 0.001, respectively). Overall, this novel multimodal nanoparticle offers new theranostic opportunities for noninvasive diagnosis and treatment of atherosclerotic plaques.
Fully Transparent Transceiver Using Single Binary Oxide Thin Film Transistors
Authors: Hassan Ali H. , Hota Mrinal K. , Alshammari Fwzah H. , Alshareef Husam N. , Salama Khaled N.
Published: February 2020

Using one binary oxide, a fully transparent thin‐film transistor (TFT)‐based transceiver circuit is presented. The proposed transceiver circuit is fabricated entirely using an atomic layer deposition process. Moreover, the proposed circuit presents two modulation schemes: frequency shift keying and ON/OFF keying. The fabricated TFTs exhibit saturation mobility, threshold voltage, a subthreshold swing, and an ON/OFF ratio of 18.2 cm2 V−1 s−1, 0.9 V, 419 mVdec−1, and 109 times, respectively. Finally, the circuit functionality is demonstrated by the word “KAUST” as a Morse code.
Enhanced Thermoelectric Performance in N‐Type Mg3.2Sb1.5Bi0.5 by La or Ce Doping into Mg
Authors: Zhang Fan , Chen Chen , Li Shan , Yin Li , Yu Bo , Sui Jiehe , Cao Feng , Liu Xingjun , Ren Zhifeng , Zhang Qian
Published: February 2020

N‐type Mg3.2Sb1.5Bi0.5 materials are prepared by cation‐site doping with lanthanides (La, Ce). Both La‐ and Ce‐doped samples exhibit a higher doping limit and greater efficiency than those of chalcogen (Te, Se, S)‐doped n‐type Mg3.2Sb1.5Bi0.5 samples. High electron carrier concentration ≈9 × 1019 cm−3 is obtained in Mg3.18La0.02Sb1.5Bi0.5 and Mg3.185Ce0.015Sb1.5Bi0.5, which is close to the theoretical doping‐concentration limit and induces contributions from more electron bands. A higher electrical conductivity was thus obtained and is beneficial to the enhanced ZT values for lanthanide‐doped Mg3.2Sb1.5Bi0.5. The highest ZT value ≈1.6 is achieved in Mg3.19La0.01Sb1.5Bi0.5 at 693 K, along with a ZT ≈1.50 in Mg3.19Ce0.01Sb1.5Bi0.5 at 693 K, indicating that lanthanides provide a promising doping strategy for Mg3.2Sb1.5Bi0.5‐based materials.
Mechanistic Study Revealing the Role of the Br3−/Br2 Redox Couple in CO2‐Assisted Li–O2 Batteries
Authors: Marques Mota Filipe , Kang Jin‐Hyuk , Jung Younguk , Park Jiwon , Na Moony , Kim Dong Ha , Byon Hye Ryung
Published: February 2020

Replacing oxygen (O2) with air is a critical step in the development of lithium (Li)–air batteries. A trace amount of carbon dioxide (CO2) in the air is, however, influentially involved in the O2 chemistry, which indicates that a fundamental understanding of the effect of CO2 is required for the design of practical cells. When up to 30% CO2 is added to Li–O2 cells, CO2 acts as an O2− scavenger. Their chemical reactions form soluble products, CO42− and C2O62−, in the tetraglyme electrolyte solution, and enhance full capacity and cell cyclability. A critical challenge is, however, the sluggish decomposition of the coproduct Li2CO3 during recharge. To lower the charging overpotential, a Br3−/Br2 redox couple is incorporated and its redox behavior is investigated using spectroscopic methods. The redox shuttle of Br3−/Br2 decomposes amorphous Li2CO3 more efficiently than its crystalline counterpart. It is revealed that Br2 combines with Br3− to form a Br2···Br3− complex, which acts as a mobile catalyst in the electrolyte solution without swift precipitation of the nonpolar Br2. This comprehensive study, revealing the molecular structure and redox process of mobile catalysts, provides an insight into improving the design of redox couples toward superior cycling performance.
Highly Efficient Perovskite Solar Cells Enabled by Multiple Ligand Passivation
Authors: Wu Zhifang , Jiang Maowei , Liu Zonghao , Jamshaid Afshan , Ono Luis K. , Qi Yabing
Published: February 2020

In the past decade, the efficiency of perovskite solar cells quickly increased from 3.8% to 25.2%. The quality of perovskite films plays vital role in device performance. The films fabricated by solution‐process are usually polycrystalline, with significantly higher defect density than that of single crystal. One kind of defect in the films is uncoordinated Pb2+, which is usually generated during thermal annealing process due to the volatile organic component. Another detrimental kind of defect is Pb0, which is often observed during the film fabrication process or solar cell operation. Because the open circuit voltage has a close relation with the defect density, it is thus desirable to passivate these two kinds of defects. Here, a molecule with multiple ligands is introduced, which not only passivates the uncoordinated Pb2+ defects, but also suppresses the formation of Pb0 defects. Meanwhile, such a treatment improves the energy level alignment between the valence band of perovskite and the highest occupied molecular orbital of spiro‐OMeTAD. As a result, the performance of perovskite solar cells significantly increases from 19.0% to 21.4%.
Energy Applications of Magnetocaloric Materials
Authors: Kitanovski Andrej
Published: February 2020

The need for energy‐efficient and environmentally friendly refrigeration, heat pumping, air conditioning, and thermal energy harvesting systems is currently more urgent than ever. Magnetocaloric energy conversion is among the best available alternatives for achieving these technological goals and has been the subject of substantial basic and applied research over the last two decades. The subject is strongly interdisciplinary, requiring proper understanding and efficient integration of knowledge in different specialized fields. This review article presents a historical and up‐to‐date account of the energy‐related applications of magnetocaloric materials and information about their processing and magnetic fields, thermodynamics, heat transfer, and other relevant characteristics. The article also discusses the conceptual design of magnetocaloric refrigeration and power generation systems and some guidelines for future research in the field.
Local Foods and Local Economic Performance
Authors: Stickel Maureen , Deller Steven
Published: February 2020

Using US county‐level data, we employ a difference‐in‐difference approach to model the effect of direct to consumer local foods activity on local economic performance. We find no evidence that growth in local foods activity is linked to economic performance measured by per capita income and some evidence of a decline in employment. These results casts doubts on the notion that the promotion of local foods can improve the performance of local economies. While the local foods market can present viable business opportunities for some producers, the overall size of the market is too thin to influence overall local economic performance.
Emergency Medicine Gender in Resident Leadership Study (EM GIRLS): The Gender Distribution Among Chief Residents
Authors: Mannix Alexandra , Parsons Melissa , Krzyzaniak Sara M. , Black Lauren Page , Alvarez Al’ai , Mody Shivani , Gottlieb Michael
Published: February 2020

Objectives

The goal of this research was to determine the gender distribution of chief residents in emergency medicine (EM) residencies in the United States to explore whether the gender leadership gap is present at the resident level in EM.

Methods

The investigators compiled a list of EM residency programs accredited by the Accreditation Council for Graduate Medical Education. Investigators reached out to the programs using established best practices in survey distribution collecting the following: program name, program location, program length, total number of residents, total number of female residents, total number of chief residents, and the total number of female chief residents.

Results

Of the 223 programs contacted 194 programs responded and 182 programs were included in the study (a response rate of 82%). As of the 2019 to 2020 academic year, female EM residents account for 37.0% (2,459/6,718) of all EM residents and female EM chief residents account for 42.2% (250/593) of EM chief residents. The proportion of female EM chief residents was significantly higher than the proportion of both female EM residents (42.2% vs. 37%, p = 0.007) and female EM attending physicians (42.2% vs. 27.5%, p < 0.001). When comparing proportions of female residents based on duration of program, female physicians comprised 35.0% (1,652/4,720) of residents at 3‐year programs and 40.4% (807/1998) of residents at 4‐year programs (p < 0.01).

Conclusions

While the proportion of female EM residents remains significantly lower than the proportion of male residents, females and males are similarly represented at the chief resident role.
Effects of defoliation and row spacing on intermediate wheatgrass II: Forage yield and economics
Authors: Hunter Mitchell C. , Sheaffer Craig C. , Culman Steven W. , Lazarus William F. , Jungers Jacob M.
Published: February 2020

Management systems that produce both grain and biomass coproducts could enhance the profitability of the novel perennial grain crop Kernza intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & D.R. Dewey] (IWG). Harvesting IWG for grain typically results in a straw harvest; in addition, vegetative biomass can be cut in spring, fall, or both for hay production. We evaluated the interacting effects of defoliation and row spacing on yield, forage quality, and economic return across the 3‐yr life of a conventionally managed IWG stand in St. Paul, MN. We measured straw and hay yield and forage quality and then used recent hay auction results to model forage price and total potential value. We then used estimated production costs to calculate potential net return from straw production alone and with additional hay harvests. Overall, straw was more valuable than hay, despite being of much lower quality, since yields were 3–4 times greater. Straw potential value was similar to the cost of producing both straw and grain, greatly reducing the financial risk in Kernza grain production. Hay production was almost always profitable. Straw and hay yield and value were greater in 15‐ and 30‐cm rows than in 61‐cm rows. Defoliating in both spring and fall led to lower hay and straw yields in the third year. Our results indicate that the best strategy for achieving consistent high net return to biomass production is to plant in 15‐ or 30‐cm rows and only cut hay in the fall.
Producer Attitudes Toward Output Price Risk: Experimental Evidence from the Lab and from the Field
Authors: Bellemare Marc F. , Lee Yu Na , Just David R.
Published: February 2020

A number of agricultural and food policy instruments are predicated on the idea that producers dislike output price risk. We test experimentally some theoretical predictions about the behavior of producers in the face of output price risk, namely Sandmo's (1971) prediction that price risk at the extensive margin causes risk‐averse producers to decrease how much they produce and Batra and Ullah's (1974) prediction that price risk at the intensive margin causes producers whose preferences exhibit decreasing absolute risk aversion to further decrease how much they produce. We do so in labs with US college students as well as in the field with Peruvian farmers. First, as regards price risk at the extensive margin, we find no support for Sandmo's prediction. Second, consistent with Batra and Ullah's prediction, we find that output decreases in response to price risk at the intensive margin when imposing a linear relationship between output and price risk. When relaxing the assumption of linearity between output and price risk, however, we find a nonmonotonic relationship between output and price risk. Taken together, these results are broadly inconsistent with expected utility theory. Alternative models of behavior in the face of risk, such as prospect theory, may explain the behavior we observe.
Reverse Endowment Effect for a New Product
Authors: Banerji A. , Rampal Jeevant
Published: February 2020

This article reports and provides an explanation for a discrepancy between two theoretically equivalent, frequently used, and incentive‐compatible methods of measuring premia for improved novel products: the full‐bidding and endow‐and‐upgrade methods. We found the following reverse endowment effect in a willingness‐to‐pay (WTP) elicitation Becker‐DeGroot‐Marschak (BDM) experiment for the newly developed biofortified high iron pearl millet (HIPM) conducted in rural India. The WTP for exchanging local pearl millet (LPM) for HIPM (the endow‐and‐upgrade measure of premium for HIPM over LPM), was significantly greater than the difference between the WTPs for HIPM and LPM (the theoretically equivalent full‐bidding measure). Our explanation is that subjects who possess an existing version of a product experience a reversal of loss aversion with respect to the novel and improved version of the product. We identify and structurally estimate the reverse loss aversion parameter. Our findings caution against using endow‐and‐upgrade and full‐bidding methods interchangeably for measuring premia for new products, even if the experimental design accounts for reciprocity and experimental‐income effect.
Effects of growth hormone treatment on thyroid function in pediatric patients with Prader–Willi syndrome
Authors: Oto Yuji , Murakami Nobuyuki , Matsubara Keiko , Saima Sohei , Ogata Hiroyuki , Ihara Hiroshi , Nagai Toshiro , Matsubara Tomoyo
Published: February 2020

It is unclear whether hypothyroidism is present in patients with Prader–Willi syndrome (PWS). This study aimed to clarify the state of the hypothalamic–pituitary–thyroid axis and the effects of growth hormone (GH) treatment on thyroid function in pediatric patients with PWS. We retrospectively evaluated thyroid function in 51 patients with PWS before GH treatment using a thyroid‐releasing hormone (TRH) stimulation test (29 males and 22 females; median age, 22 months). We also evaluated the effect of GH therapy on thyroid function by comparing serum free triiodothyronine (fT3), free thyroxine (fT4), and thyroid stimulating hormone (TSH) levels at baseline, 1 year, and 2 years after GH therapy. TSH, fT4, and fT3 levels were 2.28 μU/ml (interquartile range [IQR]; 1.19–3.61), 1.18 ng/dl (IQR; 1.02–1.24), and 4.02 pg/dl (IQR; 3.54–4.40) at baseline, respectively. In 49 of 51 patients, the TSH response to TRH administration showed a physiologically normal pattern; in two patients (4.0%), the pattern suggested hypothalamic hypothyroidism (delayed and prolonged TSH peak after TRH administration). TSH, fT4, and fT3 levels did not change significantly during 1 or 2 years after GH treatment. The TSH response to TRH showed a normal pattern in most patients, and thyroid function did not change significantly during the 2 years after initiating GH treatment.
The preparation of PA6/CS‐NPs nanofiber filaments with excellent antibacterial activity via a one‐step multineedle electrospinning method with liquid bath circling system
Authors: Jiang Rui , Yan Tao , Wang Yi‐Qi , Pan Zhi‐Juan
Published: February 2020

Because of the wide applications of the antibacterial fabrics, they have had broad‐based development recently. Chitosan is an environment‐friendly, biodegradable and natural organic antibacterial agent, which can be used to prepare the antibacterial fibers. Chitosan‐composited electrospun fibers have the potential to be applied in the fields such as surgical gowns, medical gauze, underwear, and sportswear. Therefore, using a one‐step 12‐needle electrospinning method with liquid bath circulating system, PA6/CS‐NPs nanofiber filaments would be fabricated. Under the combined effect of the drafting and impact forces, the surface of the nanofibers could adhere to a certain number of chitosan nanoparticles (CS‐NPs). By varying the mass ratios of 0.2 wt.% Span‐80/Tween‐80 (S‐80/T‐80) in the bath solution, water flow rate, and the winding rate, the filaments with different properties could be prepared. The results revealed that the surface of PA6 nanofibers could adhere to the largest number of CS‐NPs and the mechanical properties were good when the mass ratio of S‐80/T‐80 was 3/7, the water flow rate was 20 ml/min, and the roller rate was 40 r/min. The nanofibers fabricated by the optimum spinning parameters showed excellent antibacterial activity. In addition, the rate of bacteriostasis againstE. coliandS. aureuswas 99.9% and 98.9%, respectively.
Inclusion of covalent triazine framework into fluorinated polyimides to obtain composites with low dielectric constant
Authors: Purushothaman Revathi , Vaitinadin Hari Shankar
Published: February 2020

Polyimides possess good mechanical properties, favorable dielectric properties, and chemical inertness, which enabled them to find applications in microelectronic industries. The dielectric constant of the polyimides varies between 2.5 and 4, which is rather high for such applications. Hence, synthesizing polyimides with still lower dielectric constant has become one of the critical research confronts. As the properties of a terpolyimides (TPI) could be altered as per the requirement, it was synthesized by combining the dianhydrides 3,3′,4,4′‐biphenyldianhydride, 3,3′,4,4′‐oxydiphthalicdianhydride, and 4,4′‐(hexafluoroisopropylidene) with a diamine 4,4′‐(hexafluoroisopropylidene)dianiline or 2,2‐bis[4‐(4‐amino phenoxy)phenyl]hexafluoropropane. As porous covalent triazine framework (CTF‐1) is capable of capturing much air within its pores and interfacial voids, it was combined with the TPI matrix in different loadings to obtain CTF‐1/TPI composite films with low dielectric constant. The composites exhibited high thermal stability, as their thermal decomposition occurred above 520°C. The tensile properties and the dielectric constant of the composites declined with the raise in CTF‐1 loading up to 4%. The decrease in dielectric constant is essentially due to the incorporation of air voids (dielectric constant of air ~1) in the TPI matrix due to the inclusion of porous CTF‐1.
Solid‐State [2+2] Photodimerization of 1‐Aryl‐4‐pyridylbutadienes in Cation‐π‐Controlled Crystals
Authors: Yamada Shinji , Aya Kanae
Published: February 2020

Irradiation of HX (X=CF3SO3 or CF3CO2) salts of 1‐aryl‐4‐pyridylbutadienes 1 a–1 c in the solid‐state afforded syn head‐to‐tail dimers in good yields among a number of possible dimers, whereas irradiation of the neutral substrates gave a complex mixture or no products. A comparison of the X‐ray crystal structures of the neutral compounds and the HX salts clarified that their orientation modes are head‐to‐head and head‐to‐tail, respectively. Moreover, while the distances between the two neighboring double bonds of the neutral compounds are relatively far apart from each other, those of HX salts are close together, satisfying Schmidt's requirement. These findings suggested that cation‐π interactions between the pyridinium and aromatic rings are effective for the preorientation of the HX salts of substrates, leading to photodimers in high regio‐ and stereoselectivities.
Mechanochemical Synthesis of Functionalized Quinolines by Iodine Mediated Oxidative Annulation
Authors: Halder Atreyee , Maiti Debabrata , De Sarkar Suman
Published: February 2020

An iodine‐mediated environmentally benign synthesis of multi‐substituted quinoline derivatives is developed using a solvent‐free mechanochemical process. Appropriately designed and easily accessible protecting group‐free aniline derivatives were used for the oxidative annulation reaction, and a series of quinoline derivatives with variable functionalities were synthesized up to 89 % isolated yield. Importantly, the activator iodine remains in the quinoline molecule and promotes further functionalizations. The present methodology is beneficial with regard to operational simplicity and mild reaction conditions.
Group 13 Element Trihalide Complexes of Anionic N‐Heterocyclic Carbenes
Authors: Ho Luong Phong , Anders Lisa , Tamm Matthias
Published: February 2020

A series of group 13 complexes of the general type [{(WCA‐IDipp)EX3}Li(solv)] (E=B, Al, Ga, In; X=Cl, Br) that bear an anionic N‐heterocyclic carbene ligand with a weakly coordinating borate moiety (WCA‐IDipp, WCA=B(C6F5)3 and IDipp=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene) were prepared by the reaction of the respective group 13 trihalides (EX3) with the lithium salt [(WCA‐IDipp)Li ⋅ toluene]. The molecular structures of the BBr3, AlCl3, AlBr3, GaCl3 and InCl3 adducts were established by X‐ray diffraction analyses, revealing the formation of coordination polymers linked by halide‐lithium interactions, except for the indium derivative, which consists of isolated [Li(THF)4]+ and [(WCA‐IDipp)InCl3]− ions in the solid state.
Effects of Solid Acid Supports on the Bifunctional Catalysis of Levulinic Acid to γ‐Valerolactone: Catalytic Activity and Stability
Authors: Yu Zhihao , Lu Xuebin , Bai Hui , Xiong Jian , Feng Wenli , Ji Na
Published: February 2020

Heterogeneous transformation of levulinic acid (LA) to γ‐valerolactone (GVL) is regarded as a critical process of the lignocellulose‐based biorefinery system. Substantial progress on the catalytic conversion of LA to GVL has been continuously achieved recently. However, the traditional research paradigm typically emphasizes the metal‐catalyzed hydrogenation step, but lacks profound insights into the potential impacts of catalyst supports. Herein, an overview of the bifunctional catalytic system classified by representative solid acid supports for LA conversion to GVL is presented, and effects of critical factors on metal‐ and acid‐ catalyzed processes are discussed. Particularly, impacts of key issues on catalytic stability are thoroughly summarized and analyzed. Challenges and suggestions are also proposed from the perspective of increases in both catalytic activity and stability. This review potentially contributes to the rational design of high‐efficiency catalysts used in the biomass valorization for renewable energy production.
Reactive Ionic Liquid Enables the Construction of 3D Rh Particles with Nanowire Subunits for Electrocatalytic Nitrogen Reduction
Authors: Chen Tingting , Liu Shuai , Ying Hao , Li Zhonghao , Hao Jingcheng
Published: February 2020

Until now, the synthesis of Rh particles with unusual three‐dimensional (3D) nanostructures is still challenging. A 3D nanostructure enables fast ion/molecule transport and possesses plenty of exposed active surface, and therefore it is of great interest to construct 3D Rh particles catalysts for the N2 reduction reaction (NRR). Herein, we proposed a reactive ionic liquid strategy for fabricating unusual 3D Rh particles with nanowires as the subunits. The ionic liquid n‐octylammonium formate simultaneously worked as reaction medium, reductant and template for the successful construction of 3D Rh particles. The as‐prepared 3D Rh particles demonstrated excellent activity for electrocatalytic N2 fixation in 0.1 M KOH electrolyte under ambient conditions with a high NH3 yield of 35.58 μg h−1 mgcat.−1 at −0.2 V versus reversible hydrogen electrode (RHE), surpassing most of the state‐of‐the‐art noble metal catalysts. Our reactive ionic liquid strategy thus holds great promise for the rational construction of high‐performance electrocatalysts toward NRR.
Reversed Cation Selectivity of G8‐Octamer and G16‐Hexadecamer towards Monovalent and Divalent Cations
Authors: He Ying , Zhang Yanbin , Wojtas Lukasz , Akhmedov Novruz G. , Pan Qinhe , Guo Hao , Shi Xiaodong
Published: February 2020

A reverse‐binding‐selectivity between monovalent and divalent cations was observed for two different self‐assembly G16‐hexadecamer and G8‐octamer systems. The dissociation constant between G4‐quadruplex and monomer was calculated via VT‐1H NMR experiments. Quantitative energy profiles revealed entropy as the key factor for the weaker binding toward Ba2+ compared with K+ in the G8‐octamer system despite stronger ion‐dipole interactions. This study is the first direct comparison of the G4‐quartet binding affinity between mono and divalent cations and will benefit future applications of G‐quadruplex‐related research. Further competition experiments between the G8‐octamer and 18‐crown‐6 with K+ demonstrated the potential of this G8 system as a new potassium receptor.