bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Emulsion Approach to Resolve the Paradox of 3D Printing of Very Soft Silicones
Authors: Perrinet Clément , Courtial Edwin‐Joffrey , Colly Arthur , Marquette Christophe , Fulchiron René 
Published: May 2020

Abstract3D printing of silicone has been a challenge for medical applications for several years. The main property of medical silicone (mostly polydimethylsiloxane) is its mechanical similitude with human tissues. The very soft tissues as prostate, skin, liver, etc, are of Young's modulus lower than 100 kPa. 3D printing for such soft materials is not as obvious as printing thermoplastic polymers. In this work, the goal is to elaborate formulations of room‐temperature‐vulcanizing (RTV) silicone leading to final materials of Young's modulus down to 25 kPa while being processable by liquid deposition modeling, a layer by layer deposit of extruded filament. The main challenge is keeping the material with a sufficient firmness during the process to maintain the shape of the object but without increasing its final rigidity. Therefore, a RTV silicone is mixed with a hydrophilic liquid to create an emulsion of high yield stress behavior. Different emulsions are tested to optimize the composition on the basis of rheological measurements carried out to determine the yield stress variation and compare it to an emulsion model. Then, after printing and curing, the hydrophilic liquid is removed to create a material of fine porosity and consequently of low Young's modulus.
Pulsed Laser Photopatterning of Cesium Lead Halide Perovskite Structures as Robust Solution‐Processed Optical Gain Media
Authors: Tan Max J. H. , Chan Yinthai 
Published: May 2020

AbstractSolution‐processed optical gain media such as thin films of colloidal semiconductor nanocrystals promise ease of fabrication and scalable production while offering a spectrally wide range of emission colors. However, depositing such gain media in a size‐ and shape‐specific manner at a precise location on a substrate can be highly challenging. In this work, a facile approach for fabricating solution‐processed cesium lead halide perovskite structures of any arbitrary shape and size from their nanocrystal counterparts via a pulsed laser photopatterning process is demonstrated. The photopatterned structures resist solvation in both polar and nonpolar solvents, allowing for the straightforward removal of unpatterned regions. Their robustness is attributed to the ligand‐removal, sintering, and photoannealing of the nanocrystals at the site of irradiation. Concomittantly, the photopatterning process results in lengthened Auger‐dominated biexciton lifetimes and larger absorption cross‐sections that permit relatively low amplified spontaneous emission thresholds. It is shown that the photopatterning process may be used to fabricate cesium lead halide based gain media capable of multiwavelength emission, orientation‐dependent wavelength of emission, as well as functional operation while fully immersed in various solvents. It is envisioned that the photopatterning process may be extended to other perovskite systems to include applications beyond those requiring light‐emission.
A Novel Bridge‐Ring Phosphine Oxide Host 5,10‐[1,2]Benzenophosphanthrene 5,10‐Dioxide for Ultralow‐Voltage‐Driven Blue Thermally Activated Delayed Fluorescence Diodes
Authors: Gao Feifei , Du Ruiming , Jiao Fuxing , Lu Guang , Zhang Jing , Han Chunmaio , Xu Hui 
Published: May 2020

AbstractThe molecular configuration optimization is crucial for accurately controlling the intermolecular interactions of organic conjugates. Herein, with the purpose to integrate spherical geometry and optoelectronic properties, the first phosphine oxide (PO) bridge‐ring host 5,10‐[1,2]benzenophosphanthrene 5,10‐dioxide (BPAO2) with phosphorus as bridgehead atom is demonstrated. The sphere‐like paddle‐wheel configuration of BPAO2 gives rise to the highly ordered layer‐by‐layer packing mode, owing to its single molecular orientation, which provides the weak π–π interactions in each layer and hydrogen bond networks between layers. These limited but sufficient interactions are preserved in dilute solution and vacuum‐evaporated film, balancing the charge transportation and the quenching suppression. As consequence, its blue thermally activated delayed fluorescence (TADF) diodes achieve the record‐low turn‐on voltage as 2.3 V, which is remarkably below blue photon energy (≈2.6 eV), and the power efficiency up to ≈70 lm W−1. This work demonstrates the great potential of hetero bridge‐ring systems for optoelectronic applications.
Crystalline Hydrogen‐Bonded Organic Chains Achieving Ultralong Phosphorescence via Triplet–Triplet Energy Transfer
Authors: Liu Bai‐Tong , Liu En‐Ping , Sa Rong‐Jian , Liu Tian‐Fu 
Published: May 2020

AbstractUltralong organic phosphorescent (UOP) materials without any metal species have broad application prospects in optical technologies and biological imaging due to the low cost and biocompatibility. However, it is still a challenge to prepare new UOP materials with long luminous life and high photoluminescence quantum yield (PLQY). Herein, two organic molecules, 1,4‐phenylenebisboronic acid (PBA) with high PLQY and isophthalic acid (IPA) with long lifetime, are orderly combined into two crystalline hydrogen‐bonded organic chains, named as PBA‐IPA1 and PBA‐IPA2, through supramolecular self‐assembly. Compared with PBA‐IPA1, PBA‐IPA2 shows much improved phosphorescent lifetime (1.59 s) and PLQY (15.72%) due to the triplet–triplet energy transfer between two components, which is further confirmed by computational studies. The obtained material can be potentially used in such areas as information encryption and fingerprint identification, providing a new strategy for design of UOP materials for practical applications.
First Exploration on Electrochemical Activation of Low‐Cost Albite Mineral for Boosting Lithium Storage Capability
Authors: Mei Jun , Wang Tiantian , Peng Hong , Ayoko Godwin A. , Liu Jianjun , Liao Ting , Sun Ziqi 
Published: May 2020

AbstractThe direct use of natural minerals for low‐cost energy storage is a promising solution toward large‐scale and affordable sustainable energy supply, but it is usually impeded by their inert electrochemical activity. In this work, electrochemically inert albite mineral layered particles are activated as a promising low‐cost anode material for electrochemical Li+ ion storage devices through a facile thermal reduction treatment technology. Via this strategy, partial SiO2 reduction within the albite mineral particles and a conductive carbon layer on the surface are simultaneously realized, which effectively addresses the issues of inactive lithium storage and poor electric conductivity of albite minerals. Via theoretical density functional theory calculations and molecular dynamics simulations, the activation mechanism of lithium storage achieved by silica reduction is understood. This innovatively activated albite mineral delivers a maximum specific capacity of >250 mAh g−1 based on a dominant surface‐driven capacitive storage mechanism, and demonstrates excellent capacity and cycling stability at high charging/discharging rates. This design opens a new pathway to address the current cost issue in energy devices, provides insights into producing cost‐effective anodes by using silica‐rich minerals, and gives an alternative solution for improving the chemical reactivity of inorganic natural minerals toward low‐cost and large‐scale energy storages.
Photoemission Spectroscopy Characterization of Halide Perovskites
Authors: Béchu Solène , Ralaiarisoa Maryline , Etcheberry Arnaud , Schulz Philip 
Published: May 2020

AbstractControlling the surface and interface properties of halide perovskites (HaPs) materials is key to improve performance and stability of HaP‐based optoelectronic devices such as solar cells. Here, an overview is given on the use of different photoemission spectroscopy (PES) techniques as a tool kit to investigate chemical and electronic properties of surfaces and interfaces in research on HaP compounds. The primary focus of the article is X‐ray photoelectron spectroscopy (XPS), hard X‐ray photoemission spectroscopy (HAXPES), ultraviolet photoemission spectroscopy (UPS), and inverse photoemission spectroscopy (IPES), highlighting the importance of good practices during PES measurements. Starting from the working principles of PES, critical measurement conditions are discussed. In particular, the exposure of the HaP surface to vacuum and high energy radiation can cause accelerated ageing, degradation, and also ionic migration in the sample. The impact of these changes on the electronic and chemical properties is discussed, followed by an analysis of the specific challenges encountered when performing PES measurements of HaPs. These include the deviation from pristine surface conditions, determination of “soft” band edges, and assessment of band bending. The review concludes by emphasizing good practices for PES measurements of HaP samples and outlining the scope of operando type measurements to capture the transient behavior of HaPs in the experiment.
Monolithic Perovskite Tandem Solar Cells: A Review of the Present Status and Advanced Characterization Methods Toward 30% Efficiency
Authors: Jošt Marko , Kegelmann Lukas , Korte Lars , Albrecht Steve 
Published: May 2020

AbstractTandem solar cells are the next step in the photovoltaic (PV) evolution due to their higher power conversion efficiency (PCE) potential than currently dominating, but inherently limited, single‐junction solar cells. With the emergence of metal halide perovskite absorber materials, the fabrication of highly efficient tandem solar cells, at a reasonable cost, can significantly impact the future PV landscape. The perovskite‐based tandem solar cells have already shown that they can convert light more efficiently than their standalone sub‐cells. However, to reach PCEs over 30%, several challenges have to be overcome and the understanding of this fascinating technology has to be broadened. In this review, the main scientific and engineering challenges in the field are presented, alongside a discussion of the current status of three main perovskite tandem technologies: perovskite/silicon, perovskite/CIGS, and perovskite/perovskite tandem solar cells. A summary of the advanced structural, electrical, optical, radiative, and electronic characterization methods as well as simulations being utilized for perovskite‐based tandem solar cells is presented. The main findings are summarized and the strength of the techniques to overcome the challenges and gain deeper knowledge for further performance improvement is assessed. Finally, the PCE potential in different experimental and theoretical limits is compared with an aim to shed light on the path towards overcoming the 30% efficiency threshold for all of the three herein reviewed tandem technologies.
Femtosecond Laser‐Etched MXene Microsupercapacitors with Double‐Side Configuration via Arbitrary On‐ and Through‐Substrate Connections
Authors: Li Qiang , Wang Qizhao , Li Linlin , Yang Lijun , Wang Yang , Wang Xiaohui , Fang Hai‐Tao 
Published: May 2020

AbstractThe capacitance of microsupercapacitors (MSCs) can double if both sides of substrates are used to construct MSCs. Nevertheless, achieving electric connections of MSCs through substrates is a challenge due to the difficulty in precisely positioning each MSC couple that has two of the same MSCs units on two sides. In this work, taking advantage of the synchronous etching on both sides of transparent polyethylene terephthalate substrates by femtosecond laser pulses, a double‐sided configuration is attained with high precision in the alignment of back‐to‐back MSC couples and versatile double‐side MSCs are realized via arbitrary on‐ and through‐substrate connections of MXene MSC units. The MXene double‐side MSC fabricated by the series connection of 12 spiral pattern MXene MSC units with interdigital electrodes of 10 μm width interspace can output a large working voltage of 7.2 V. Additionally, femtosecond laser etching brings the transformation of MXene into titania near‐etched edges with a lateral distance less than 1 µm. Such a small laser‐affected area has little influence on the capacitive performance, which is one of advantages for femtosecond laser over conventional lasers. This research is valuable for one‐step manufacturing of highly integrated MSCs in the field of miniaturized energy storage systems.
Fluorinating π‐Extended Molecular Acceptors Yields Highly Connected Crystal Structures and Low Reorganization Energies for Efficient Solar Cells
Authors: Swick Steven M. , Alzola Joaquin M. , Sangwan Vinod K. , Amsterdam Samuel H. , Zhu Weigang , Jones Leighton O. , Powers‐Riggs Natalia , Facchetti Antonio , Kohlstedt Kevin L. , Schatz George C. , Hersam Mark C. , Wasielewski Michael R. , Marks Tobin J. 
Published: May 2020

AbstractThe synthesis and characterization of new semiconducting materials is essential for developing high‐efficiency organic solar cells. Here, the synthesis, physiochemical properties, thin film morphology, and photovoltaic response of ITN‐F4 and ITzN‐F4, the first indacenodithienothiophene nonfullerene acceptors that combine π‐extension and fluorination, are reported. The neat acceptors and bulk‐heterojunction blend films with fluorinated donor polymer poly{[4,8‐bis[5‐(2‐ethylhexyl)‐4‐fluoro‐2‐thienyl]benzo[1,2‐b:4,5‐b′]‐dithiophene‐2,6‐diyl]‐alt‐[2,5‐thiophenediyl[5,7‐bis(2‐ethylhexyl)‐4,8‐dioxo‐4H,8H‐benzo[1,2‐c:4,5‐c′]dithiophene‐1,3‐diyl]]} (PBDB‐TF, also known as PM6) are investigated using a battery of techniques, including single crystal X‐ray diffraction, fs transient absorption spectroscopy (fsTA), photovoltaic response, space‐charge‐limited current transport, impedance spectroscopy, grazing incidence wide angle X‐ray scattering, and density functional theory level computation. ITN‐F4 and ITzN‐F4 are found to provide power conversion efficiencies greater and internal reorganization energies less than their non‐π‐extended and nonfluorinated counterparts when paired with PBDB‐TF. Additionally, ITN‐F4 and ITzN‐F4 exhibit favorable bulk‐heterojunction relevant single crystal packing architectures. fsTA reveals that both ITN‐F4 and ITzN‐F4 undergo ultrafast hole transfer (<300 fs) in films with PBDB‐TF, despite excimer state formation in both the neat and blend films. Taken together and in comparison to related structures, these results demonstrate that combined fluorination and π‐extension synergistically promote crystallographic π‐face‐to‐face packing, increase crystallinity, reduce internal reorganization energies, increase interplanar π–π electronic coupling, and increase power conversion efficiency.
Rationally Designed Dual‐Mode Triboelectric Nanogenerator for Harvesting Mechanical Energy by Both Electrostatic Induction and Dielectric Breakdown Effects
Authors: Zhou Linglin , Liu Di , Li Shaoxin , Zhao Zhihao , Zhang Chunlei , Yin Xin , Liu Li , Cui Shengnan , Wang Zhong Lin , Wang Jie 
Published: May 2020

AbstractWith the advantages of its light weight, low cost, and high efficiency especially at low operation frequency, the triboelectric nanogenerator (TENG) is considered to be a potential solution for self‐powered sensor networks and large‐scale renewable blue energy. However, the conventional TENG converts mechanical energy into electrical energy only via either electrostatic induction or electrostatic breakdown. Here, a novel dual‐mode TENG is presented, which can simultaneously harvest mechanical energy by electrostatic induction and dielectric breakdown in a single device. Based on the complementary working mechanism, it achieves a great improvement in the output performance with the sum of two TENGs via a single mechanism and reveals the effect of dielectric layer thickness on the triboelectrification, electrostatic induction, and air breakdown. This study establishes a new methodology to optimize TENGs and provides a new tool to investigate the triboelectrification, electrostatic induction and dielectric breakdown simultaneously.
Are Farmers Made Whole by Trade Aid?
Authors: Janzen Joseph P. , Hendricks Nathan P. 
Published: May 2020

AbstractThe USDA provided roughly $23.5 billion in Market Facilitation Program payments to compensate farmers for market losses due to retaliatory tariffs imposed by China and other countries. We examine the distribution of these payments across crops, farms, and regions. Payment rates are larger than estimated price impacts of retaliatory tariffs for most commodities—the difference is especially large for cotton and sorghum. Payment rates relative to farmland cash rent or on a per‐farm basis are greatest in the South. While payments exceed the tariff‐related price impact in the short run, the program may not compensate for long‐run losses due to the trade conflict.
Herbage responses and nitrogen agronomic efficiency of bahiagrass–legume mixtures
Authors: Santos Erick R. S. , Dubeux Jose C. B. , Jaramillo David M. , Garcia Liza , Mackowiak Cheryl L. , Blount Ann R. S. , Pereira‐Neto Jose D. , Queiroz Luana M. D. , Ruiz‐Moreno Martin 
Published: May 2020

AbstractBahiagrass (Paspalum notatum Flüggé) is the most utilized forage in Florida and requires N fertilization to optimize production. Integrating legumes into bahiagrass pastures may reduce N fertilizer inputs and improve forage nutritive value. This 2‐yr, 2‐location, on‐farm study established two legumes, alfalfa (Medicago sativa L.) or rhizoma peanut (RP; Arachis glabrata Benth.), in mixtures with bahiagrass. We compared bahiagrass–legume mixtures + 45 kg N ha−1 harvest−1 with their non‐N fertilized monocultures and with bahiagrass + 90 kg N ha−1 harvest−1 (N‐fertilized bahiagrass). Treatments were bahiagrass, N‐fertilized bahiagrass, bahiagrass–alfalfa, bahiagrass–RP, alfalfa, and RP. Variables analyzed included herbage accumulation (HA), botanical composition, forage N concentration, forage total N aboveground (TNAG), and N agronomic efficiency. Mixtures and N‐fertilized bahiagrass resulted in similar cumulative HA (10,400 kg dry matter [DM] ha−1 yr−1, on average) and they were greater than all other treatments (4,190 kg DM ha−1 yr−1, on average). Alfalfa and RP represented low proportions of the mixed swards, with alfalfa proportion being as high as 16.1% and as low as 1.6%. Rhizoma peanut greatest proportion was 2.1% and the lowest was 0.5%. Mixtures and N‐fertilized bahiagrass maintained similar N concentrations, but they were consistently lower than legume monocultures. The N‐fertilized bahiagrass and mixture treatments resulted in the greatest TNAG in four out of the six sampling dates. The AEN of mixtures was typically greater than N‐fertilized bahiagrass. Since legumes had low proportion in mixtures, 45 kg N ha−1 harvest−1 was the upper limit for reaching maximum HA in bahiagrass.
Site‐Selective Trifluoromethylation Reactions of Oligopeptides
Authors: Guerrero Itziar , Correa Arkaitz 
Published: May 2020

AbstractSite‐selective chemical modifications that target proteinogenic amino acid residues complement the methods entailing genetic manipulation, thereby allowing straightforward and rapid access to engineered proteins. The incorporation of the trifluoromethyl group into amino acids within a peptide sequence results in relevant peptidomimetics with unique biomedicinal properties. As a result, the last decade has witnessed the development of a powerful set of protocols toward the selective trifluoromethylation of small‐to‐medium size peptides and proteins in a late‐stage fashion. This minireview seeks to highlight those particularly compelling cases published in the last years.
Use of high‐fidelity 3‐dimensional–printed models for training novice residents in basic nasal endoscopic skills
Authors: Dong Dong , Liu Wentao , Wu Shuangxia , Cai Fangyu , Wang Yue , Lyu Lei , Zhao Yulin , Zhang Yanbing 
Published: May 2020

BackgroundThe use of 3‐dimensional (3D)–printed models is promising in nasal endoscopic technique training. Here, we aimed to develop postsurgical simulants for use in conjunction with 3D‐printed nasal models and to assess their usefulness in helping residents transfer basic endoscopic skills acquired during simulation training to clinical situations.MethodsThe secretion simulant was prepared via a crosslinked reaction between sodium alginate and acrylamide, whereas the packing simulant was prepared using a superabsorbent polymer. After the simulants’ fidelity and utility were evaluated by 5 rhinologists using a 5‐point Likert scale, 46 novice residents were trained using the 3D‐printed nasal models and postsurgical simulants for 2 weeks. A checklist and Global Rating Scale (GRS) were used to assess their performances before and after training, and the time to finish each task was also recorded. Following training, the qualified trainees operated on real patients and were reevaluated.ResultsThe simulants’ similarity and usefulness scored ≥4.0, and the training cost was 28 CNY ($4 USD) per session. Following training, the checklist and GRS scores increased, and the operation time decreased (all p < 0.05). There were no statistical differences between the trainees’ performances on the models with the simulants and on patients (all p > 0.05).ConclusionThe low‐cost simulated secretion and dressing are safe to use. The application of the simulants in conjunction with that of 3D‐printed nasal models in a simulated task setting can help residents in transferring endoscopic skills acquired during simulation teaching to real patients.
A Conjugate Addition Approach to Diazo‐Containing Scaffolds with β Quaternary Centers
Authors: Fang Jian , Howard Evan M. , Brewer Matthias 
Published: May 2020

AbstractStructurally complex diazo‐containing scaffolds are formed by conjugate addition to vinyl diazonium salts. The electrophile, a little studied α‐diazonium‐α,β‐unsaturated carbonyl compound, is formed at low temperature under mild conditions by treating β‐hydroxy‐α‐diazo carbonyls with Sc(OTf)3. Conjugate addition occurs selectively at the 3‐position of indole to give α‐diazo‐β‐indole carbonyls, and enoxy silanes react to give 2‐diazo‐1,4‐dicarbonyl products. These reactions result in the formation of tertiary and quaternary centers, and give products that would be otherwise difficult to form. Importantly, the diazo functional group is retained within the molecule for future manipulation. Treating an α‐diazo ester indole addition product with Rh2(OAc)4 caused a rearrangement to occur to give a 2‐(1H‐indol‐3‐yl)‐2‐enoate. In the case of diazo ketone compounds, this shift occurred spontaneously on prolonged exposure to the Lewis acidic reaction conditions.