bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantum Confinement of Dirac Quasiparticles in Graphene Patterned with Sub‐Nanometer Precision
Authors: Cortés‐del Río Eva , Mallet Pierre , González‐Herrero Héctor , Lado José Luis , Fernández‐Rossier Joaquín , Gómez‐Rodríguez José María , Veuillen Jean‐Yves , Brihuega Iván
Published: June 2020

Quantum confinement of graphene Dirac‐like electrons in artificially crafted nanometer structures is a long sought goal that would provide a strategy to selectively tune the electronic properties of graphene, including bandgap opening or quantization of energy levels. However, creating confining structures with nanometer precision in shape, size, and location remains an experimental challenge, both for top‐down and bottom‐up approaches. Moreover, Klein tunneling, offering an escape route to graphene electrons, limits the efficiency of electrostatic confinement. Here, a scanning tunneling microscope (STM) is used to create graphene nanopatterns, with sub‐nanometer precision, by the collective manipulation of a large number of H atoms. Individual graphene nanostructures are built at selected locations, with predetermined orientations and shapes, and with dimensions going all the way from 2 nm up to 1 µm. The method permits the patterns to be erased and rebuilt at will, and it can be implemented on different graphene substrates. STM experiments demonstrate that such graphene nanostructures confine very efficiently graphene Dirac quasiparticles, both in 0D and 1D structures. In graphene quantum dots, perfectly defined energy bandgaps up to 0.8 eV are found that scale as the inverse of the dot’s linear dimension, as expected for massless Dirac fermions.
Conversion of Intercalated MoO3 to Multi‐Heteroatoms‐Doped MoS2 with High Hydrogen Evolution Activity
Authors: Yang Weiwei , Zhang Shuqing , Chen Qian , Zhang Chao , Wei Yi , Jiang Huaning , Lin Yunxiang , Zhao Mengting , He Qianqian , Wang Xingguo , Du Yi , Song Li , Yang Shubin , Nie Anmin , Zou Xiaolong , Gong Yongji
Published: June 2020

Lack of effective strategies to regulate the internal activity of MoS2 limits its practical application for hydrogen evolution reactions (HERs). Doping of heteroatoms without forming aggregation or an edge enrichment is still challenging, and its effect on the HER needs to be further explored. Herein, a two‐step method is developed to obtain multi‐metal‐doped H‐MoS2, which includes intercalation of the layered MoO3 precursor with a following sulfurization. Benefiting from the capability of the intercalation method to uniformly and simultaneously introduce different elements into the van der Waals gap, this method is universal to obtain multi‐heteroatoms co‐doped MoS2 without forming clusters, phase separation, and an edge enrichment. It is demonstrated that the doping of adjacent cobalt and palladium monomers on MoS2 greatly enhances the HER catalytic activity. The overpotential at 10 mA cm−2 and Tafel slope of Co and Pd co‐doped MoS2 is found to be 49.3 mV and 43.2 mV dec−1, respectively, representing a superior acidic HER catalytic activity. This intercalation‐assisted method also provides a new and general strategy to synthesize uniformly doped transition metal dichalcogenides for various applications.
Directed Assembly of Liquid Metal–Elastomer Conductors for Stretchable and Self‐Healing Electronics
Authors: Krisnadi Febby , Nguyen Linh Lan , Ankit  , Ma Jinwoo , Kulkarni Mohit Rameshchandra , Mathews Nripan , Dickey Michael D.
Published: June 2020

Growing interest in soft robotics, stretchable electronics, and electronic skins has created demand for soft, compliant, and stretchable electrodes and interconnects. Here, dielectrophoresis (DEP) is used to assemble, align, and sinter eutectic gallium indium (EGaIn) microdroplets in uncured poly(dimethylsiloxane) (PDMS) to form electrically conducting microwires. There are several noteworthy aspects of this approach. 1) Generally, EGaIn droplets in silicone at loadings approaching 90 wt% remain insulating and form a conductive network only when subjected to sintering. Here, DEP facilitates assembly of EGaIn droplets into conductive microwires at loadings as low as 10 wt%. 2) DEP is done in silicone for the first time, enabling the microwires to be cured in a stretchable matrix. 3) Liquid EGaIn droplets sinter during DEP to form a stretchable metallic microwire that retains its shape after curing the silicone. 4) Use of liquid metal eliminates the issue of compliance mismatch observed in soft polymers with solid fillers. 5) The silicone–EGaIn “ink” can be assembled by DEP within the crevices of severely damaged wires to create stretchable interconnects that heal the damage mechanically and electrically. The DEP process of this unique set of materials is characterized and the interesting attributes enabled by such liquid microwires are demonstrated.
Multiply Charged Conjugated Polyelectrolytes as a Multifunctional Interlayer for Efficient and Scalable Perovskite Solar Cells
Authors: Jung Eui Dae , Harit Amit Kumar , Kim Do Hui , Jang Chung Hyeon , Park Jong Hyun , Cho Shinuk , Song Myoung Hoon , Woo Han Young
Published: June 2020

A series of anionic conjugated polyelectrolytes (CPEs) is synthesized based on poly(fluorene‐co‐phenylene) by varying the side‐chain ionic density from two to six per repeat units (MPS2‐TMA, MPS4‐TMA, and MPS6‐TMA). The effect of MPS2, 4, 6‐TMA as interlayers on top of a hole‐extraction layer of poly(bis(4‐phenyl)‐2,4,6‐trimethylphenylamine (PTAA) is investigated in inverted perovskite solar cells (PeSCs). Owing to the improved wettability of perovskites on hydrophobic PTAA with the CPEs, the PeSCs with CPE interlayers demonstrate a significantly enhanced device performance, with negligible device‐to‐device dependence relative to the reference PeSC without CPEs. By increasing the ionic density in the MPS‐TMA interlayers, the wetting, interfacial defect passivation, and crystal growth of the perovskites are significantly improved without increasing the series resistance of the PeSCs. In particular, the open‐circuit voltage increases from 1.06 V for the PeSC with MPS2‐TMA to 1.11 V for the PeSC with MPS6‐TMA. The trap densities of the PeSCs with MPS2,4,6‐TMA are further analyzed using frequency‐dependent capacitance measurements. Finally, a large‐area (1 cm2) PeSC is successfully fabricated with MPS6‐TMA, showing a power conversion efficiency of 18.38% with negligible hysteresis and a stable power output under light soaking for 60 s.
Chiral Assemblies of Laser‐Printed Micropillars Directed by Asymmetrical Capillary Force
Authors: Hu Yanlei , Yuan Hongwei , Liu Shunli , Ni Jincheng , Lao Zhaoxin , Xin Chen , Pan Deng , Zhang Yiyuan , Zhu Wulin , Li Jiawen , Wu Dong , Chu Jiaru
Published: June 2020

Artificial microstructures composed of chiral building blocks are of great significance in the fields of optics and mechanics. Here, it is shown that highly ordered chiral structures can be spontaneously assembled by a meniscus‐directed capillary force arising in an evaporating liquid. The chirality is facilitated by rationally breaking the intrinsic symmetry in the unit cells through cooperative control of the geometry and spatial topology of the micropillars. The interfacial dynamics of the assembly process are studied to show that the sequential self‐organization of the micropillars is influenced by the geometries, stiffness, and spatial arrangements. A diversity of chiral assemblies with controlled handedness is yielded by varying the pillar number, height, cross‐section, laser power, and spatial topology. Lastly, the differential reflectance of light carrying opposite orbital angular momentums on the assembled chiral architectures are investigated, showcasing their potential in the field of chiral photonics concerning enantioselective response and exceptional optical functions.
Soft Electronics for the Skin: From Health Monitors to Human–Machine Interfaces
Authors: Rao Zhoulyu , Ershad Faheem , Almasri Abdullah , Gonzalez Lei , Wu Xiaoyang , Yu Cunjiang
Published: June 2020

Conventional bulky and rigid electronics prevent compliant interfacing with soft human skin for health monitoring and human–machine interaction, due to the incompatible mechanical characteristics. To overcome the limitations, soft skin‐mountable electronics with superior mechanical softness, flexibility, and stretchability provide an effective platform for intimate interaction with humans. In addition, soft electronics offer comfortability when worn on the soft, curvilinear, and dynamic human skin. Herein, recent advances in soft electronics as health monitors and human–machine interfaces (HMIs) are briefly discussed. Strategies to achieve softness in soft electronics including structural designs, material innovations, and approaches to optimize the interface between human skin and soft electronics are briefly reviewed. Characteristics and performances of soft electronic devices for health monitoring, including temperature sensors, pressure sensors for pulse monitoring, pulse oximeters, electrophysiological sensors, and sweat sensors, exemplify their wide range of utility. Furthermore, the soft electronic devices for prosthetic limb, household object, mobile machine, and virtual object control are presented to highlight the current and potential implementations of soft electronics for a broad range of HMI applications. Finally, the current limitations and future opportunities of soft skin‐mountable electronics are also discussed.
A Gel‐Free Ti3C2Tx‐Based Electrode Array for High‐Density, High‐Resolution Surface Electromyography
Authors: Murphy Brendan B. , Mulcahey Patrick J. , Driscoll Nicolette , Richardson Andrew G. , Robbins Gregory T. , Apollo Nicholas V. , Maleski Kathleen , Lucas Timothy H. , Gogotsi Yury , Dillingham Timothy , Vitale Flavia
Published: June 2020

Wearable sensors for surface electromyography (EMG) are composed of single‐ to few‐channel large‐area contacts, which exhibit high interfacial impedance and require conductive gels or adhesives to record high‐fidelity signals. These devices are also limited in their ability to record activation across large muscle groups due to poor spatial coverage. To address these challenges, a novel high‐density EMG array is developed based on titanium carbide (Ti3C2Tx) MXene encapsulated in parylene‐C. Ti3C2Tx is a 2D nanomaterial with excellent electrical, electrochemical, and mechanical properties, which forms colloidally stable aqueous dispersions, enabling safe, scalable solutions‐processing. Leveraging the excellent combination of metallic conductivity, high pseudocapacitance, and ease of processability of Ti3C2Tx MXene, the fabrication of gel‐free, high‐density EMG arrays is demonstrated, which are ≈8 µm thick, feature 16 recording channels, and are highly skin conformable. The impedance of Ti3C2Tx electrodes in contact with human skin is 100–1000× lower than the impedance of commercially available electrodes which require conductive gels to be effective. Furthermore, the arrays can record high‐fidelity, low‐noise EMG, and can resolve muscle activation with improved spatiotemporal resolution and sensitivity compared to conventional gelled electrodes. Overall, the results establish Ti3C2Tx‐based bioelectronic interfaces as a powerful platform technology for high‐resolution, noninvasive wearable sensing technologies.
Boosting Efficiency of Near‐Infrared Emitting Iridium(III) Phosphors by Administrating Their π–π Conjugation Effect of Core–Shell Structure in Solution‐Processed OLEDs
Authors: You Caifa , Liu Denghui , Yu Junting , Tan Hua , Zhu Mengbing , Zhang Bin , Liu Yu , Wang Yafei , Zhu Weiguo
Published: June 2020

High‐efficiency near‐infrared (NIR) phosphorescent emitter is still a great challenge in solution processable organic light‐emitting diodes (OLEDs). Herein, four novel NIR‐emitting iridium(III) complexes with core–shell structure, named as Ir1, Ir2, Ir3, and Ir4, are rationally designed and synthesized, in which the highly rigid dibenzo[a,c] phenazine (DBPz) moiety is used as coordinated core and the flexible hexyl‐thienyl or 4‐(N,N‐diphenylamino)phenyl as peripheral shell anchored in 3, 6‐, or 11, 12‐positions of DBPz. The influence of the core–shell structure on molecular aggregation, photophysical properties, and electroluminescent (EL) performance is systematically investigated. It is found that core–shell structure and substituted positions of shells have great influences on properties of iridium(III) complexes. Intense NIR emissions at 710–740 nm are observed with luminescent quantum yields of 18–30% in these complexes. Solution‐processed NIR‐OLEDs based on Ir3 or Ir4 show better electroluminescent properties. The maximum external quantum efficiency of 13.72% with a radiance of 26 996 mW Sr−1 m−2 (@708 nm) is obtained in Ir3‐doped OLEDs, representing the state‐of‐the‐art EL performance in the iridium complex‐based NIR‐OLEDs. This work demonstrates that administrating π–π conjugation effects of core–shell structure in C^N ligand is a new avenue to obtain high‐efficiency NIR‐emitting iridium(III) complexes.
Reversible On–Off of Chirality and Anisotropy in Patterned Coexistence of Achiral‐Anisotropic and Chiral‐Isotropic Soft Materials
Authors: Mo Qinyu , Liu Binghui , Huang Wenbin , Sun Pei‐Zhi , Li Zhiying , Bisoyi Hari Krishna , Shen Dong , Zheng Zhi‐Gang , Lu Yan‐Qing , Li Quan
Published: June 2020

Achieving a coexistence of two or multiple phases of soft matters via a delicate trade‐off of free energy and long‐range order with one another has been inspiring abundant interest on fundamental sciences and engineering. In this work, a stable coexistence of the optically achiral‐anisotropic liquid crystalline nematic phase and the optically chiral‐isotropic liquid crystalline blue phase is proposed and demonstrated, with their distribution tailored in a micro‐pattern by the developed localized micro‐regional polymer templating technique. Such a stable patterned coexistence of the two different phases with a distinct molecular arrangement, optical chirality, and anisotropy is achieved depending on a delicate matching of the elastic energy on the interface between liquid crystals and polymer networks. In contrast to the majority of soft coexistence systems, a specific dynamic and reversible on–off response of chirality and anisotropy is observed in such a system driven by an electric field. The structure of patterned coexistence system in the presence and absence of external stimulation is explored by microscopy and optical technique, and furthermore, the prospective photonic applications are demonstrated. This investigation indicates another category of functional soft material with fantastic adaptive characteristics for application in optics, electronics, interface physics, and chemistry.
Plasmon Hybridization in Compressible Metal–Insulator–Metal Nanocavities: An Optical Approach for Sensing Deep Sub‐Wavelength Deformation
Authors: Carrara Angelica , Maccaferri Nicolò , Cerea Andrea , Bozzola Angelo , De Angelis Francesco , Proietti Zaccaria Remo , Toma Andrea
Published: June 2020

A pressure‐induced deformation‐sensitive device (DSD) is presented based on 2D matrices of plasmonic gold nanodisks coupled to a metal thin layer through a compressible dielectric spacer, namely a deformable metal–insulator–metal (MIM) nanocavity, to report deep sub‐wavelength size variations (<λ/200). The system is characterized by two hybrid branches, which are resonant in the visible/near infrared spectral region. The fundamental mode, owing to the near‐field interaction between the plasmonic nanostructures and the metal film, exhibits a remarkable sensitivity to the gap size, exceeding that of a planar “macroscopic” optical cavity and extending its operational domain to the sub‐wavelength range, where excellent opportunities toward truly multiscale MIMs‐based pressure sensors can be envisioned. Concurrently, its intrinsic plasmonic nature synergistically combines into a single platform multi‐purpose functionalities, such as ultrasensitive detection and remote temperature readout, with practical perspectives in ultra‐compact inspection tools for structural and functional information at the nanoscale.
Synthesis of Seleno‐Heterocycles via Electrophilic/Radical Cyclization of Alkyne Containing Heteroatoms
Authors: Sonawane Amol D. , Sonawane Rohini A. , Ninomiya Masayuki , Koketsu Mamoru
Published: June 2020

containing heterocyclic scaffolds by virtue of their interesting reactivities and a broad range of applications in the medicinal and materials chemistry. This review involves the electrophilic/radical cyclization of alkynes containing heteroatoms which resulted into the novel Se‐heterocycles. The synthesis of seleno‐heterocycles via different nucleophiles including O, N, S, Se, Te, and C‐nucleophiles is exhaustively discussed. Also, one‐pot electrophilic cyclization of 1,3‐diynes and 1,3,5‐triynes was described in details. Furthermore, the various mechanisms underlying the synthesis of selenium‐β‐lactam, carbapenem heterocycle, bis‐ and tris‐selenide alkene, β‐selenosulfonation and selenated alkynes were discussed. The Se‐heterocycles reported in this review allow preparing these selenated compounds bearing the selenium moiety both on the rings (outside) and inside the ring (e. g. selenophenes). The review demonstrates the growing opportunities to construct selenium containing heterocycles from alkynes containing heteroatoms.

magnified image
Fast Charging Materials for High Power Applications
Authors: Babu Binson , Simon Patrice , Balducci Andrea
Published: June 2020

An overview of fast charging materials for high power applications is given. The behavior at high current density of several anodic and cathodic materials that have been utilized in lithium‐, sodium‐, and potassium‐ion batteries is considered. Furthermore, the behavior of capacitive and pseudocapacitive materials suitable for electrochemical capacitors and, also, of those that have been utilized for the realization of hybrid‐ion capacitors, which are nowadays an interesting reality in the field of high power devices, is discussed. The advantages and limitations of all these materials are critically analyzed with the aim of understanding their impact on real devices. On the basis of this analysis, the most important aspects are identified, which should be addressed in the future for the realization of advanced high power devices.
Chronic stress and age‐related pattern of blood pressure: A cross‐sectional study in rural China
Authors: Yazawa Aki , Inoue Yosuke , Tu Raoping , Yamamoto Taro , Watanabe Chiho , Kawachi Ichiro
Published: June 2020

Objective

Chronic stress is a risk factor for hypertension in adults. However, there is conflicting evidence for older adults. We hypothesized that age‐related arterial stiffening, which leads to a lower blood pressure (especially diastolic blood pressure [DBP]), is more pronounced among older adults with high vs low stress. The objectives of this study were (a) to investigate age‐related trends in systolic and DBPs among adults in rural Fujian, China, and (b) to examine differences in age‐related blood pressure trends according to levels of stress by using Epstein‐Barr virus (EBV) antibody titer as a marker of chronic stress status.

Methods

We collected cross‐sectional data from 764 rural community‐dwelling adults in rural Fujian, China (mean age = 59.4). Participants were categorized into high and low stress groups by median split of EBV antibody titer. A least‐squares regression analysis was used to investigate the association between age and blood pressures.

Results

We observed an inverted U‐shaped association between age and DBP, while there was a linear association between age and systolic blood pressure in the overall sample. When stratified by stress, the inverted U‐shaped associations with age (both systolic and DBPs) were seen only among those with high stress; DBP peaked at the age of ~68 years, and the declining trend later in life was more clearly observed among those with high chronic stress.

Discussion

Decrease of DBP was more pronounced among older adults with high vs low chronic stress in rural China.
Apolipoprotein E knockout rabbit model of intracranial atherosclerotic disease
Authors: Zabriskie Matthew S. , Wang Chuanzhuo , Wang Shuping , Alexander Matthew D.
Published: June 2020

Intracranial atherosclerotic disease (ICAD) is the most common cause of ischemic stroke. Poor understanding of the disease due to limited human data leads to imprecise treatment. Apolipoprotein E knockout (ApoE‐KO) rabbits were compared to an existing model, the Watanabe heritable hyperlipidemic (WHHL) rabbit, and wild‐type New Zealand white (NZW) rabbit controls. Intracranial artery samples were assessed on histopathology for the presence of ICAD. Logistic and ordinal regression analyses were performed to assess for disease presence and severity, respectively. Eighteen rabbits and 54 artery segments were analyzed. Univariate logistic analysis confirmed the presence of ICAD in model rabbits (P < .001), while no difference was found between WHHL and ApoE‐KO rabbits (P = .178). In multivariate analysis, only classification as a model vs wild‐type animal (P < .001) was associated with the presence of ICAD. Univariate ordinal regression analysis demonstrated an association between ICAD severity and model animals (P = .001), with no difference was noted between WHHL and ApoE‐KO rabbits (P = .528). In multivariate ordinal regression analysis, only classification as a model retained significance (P < .001). ICAD can be reliably produced in ApoE‐KO rabbits, developing the disease comparably to the older WHHL model. Further analysis is warranted to optimize accelerated development of ICAD in ApoE‐KO rabbits to more efficiently study this disease.
Development and Validation of Forecasting Next Reported Seizure Using e‐Diaries
Authors: Goldenholz Daniel M. , Goldenholz Shira R. , Romero Juan , Moss Rob , Sun Haoqi , Westover Brandon
Published: June 2020

Objective

There are no validated methods for predicting the timing of seizures. Using machine learning, we sought to forecast 24‐hour risk of self‐reported seizure from e‐diaries.

Methods

Data from 5,419 patients on SeizureTracker.com (including seizure count, type, and duration) were split into training (3,806 patients/1,665,215 patient‐days) and testing (1,613 patients/549,588 patient‐days) sets with no overlapping patients. An artificial intelligence (AI) program, consisting of recurrent networks followed by a multilayer perceptron (“deep learning” model), was trained to produce risk forecasts. Forecasts were made from a sliding window of 3‐month diary history for each day of each patient's diary. After training, the model parameters were held constant and the testing set was scored. A rate‐matched random (RMR) forecast was compared to the AI. Comparisons were made using the area under the receiver operating characteristic curve (AUC), a measure of binary discrimination performance, and the Brier score, a measure of forecast calibration. The Brier skill score (BSS) measured the improvement of the AI Brier score compared to the benchmark RMR Brier score. Confidence intervals (CIs) on performance statistics were obtained via bootstrapping.

Results

The AUC was 0.86 (95% CI = 0.85–0.88) for AI and 0.83 (95% CI = 0.81–0.85) for RMR, favoring AI (p < 0.001). Overall (all patients combined), BSS was 0.27 (95% CI = 0.23–0.31), also favoring AI (p < 0.001).

Interpretation

The AI produced a valid forecast superior to a chance forecaster, and provided meaningful forecasts in the majority of patients. Future studies will be needed to quantify the clinical value of these forecasts for patients. ANN NEUROL 2020;88:588–595
The Aluminyl Anion: A New Generation of Aluminium Nucleophile
Authors: Hicks Jamie , Vasko Petra , Goicoechea Jose M. , Aldridge Simon
Published: June 2020

Trivalent aluminium compounds are well known for their reactivity as Lewis acids/electrophiles, a feature that is exploited in many pharmaceutical, industrial and laboratory‐based reactions. Recently, a series of isolable aluminium(I) anions (“aluminyls”) have been reported, which offer an alternative to this textbook description: these reagents behave as aluminium nucleophiles. This minireview covers the synthesis, structure and reactivity of aluminyl species reported to date, together with their associated metal complexes. The frontier orbitals of each of these species have been investigated using a common methodology to allow for a like‐for‐like comparison of their electronic structure and a means of rationalising (sometimes unprecedented) patterns of reactivity.
Revisiting the Intriguing Electronic Features of the BeOBeC Carbyne and Some Isomers: A Quantum‐Chemical Assessment
Authors: Li Jilai , Geng Caiyun , Weiske Thomas , Zhou Mingfei , Li Jun , Schwarz Helmut
Published: June 2020

Extensive high‐level quantum‐chemical calculations reveal that the rod‐shaped molecule BeOBeC, which was recently generated in matrix experiments, exists in two nearly isoenergetic states, the 5Σ quintet (56) and the 3Σ triplet (36). Their IR features are hardly distinguishable at finite temperature. The major difference concerns the mode of spin coupling between the terminal beryllium and carbon atoms. Further, the ground‐state potential‐energy surface of the [2Be,C,O] system at 4 K is presented and differences between the photochemical and thermal behaviors are highlighted. Finally, a previously not considered, so far unknown C2v‐symmetric rhombus‐like four‐membered ring 3[Be(O)(C)Be] (35) is predicted to represent the global minimum on the potential‐energy surface.
Pressure‐Induced Conversion of a Paramagnetic FeCo Complex into a Molecular Magnetic Switch with Tuneable Hysteresis
Authors: Li Yanling , Benchohra Amina , Xu Buqin , Baptiste Benoît , Béneut Keevin , Parisiades Paraskevas , Delbes Ludovic , Soyer Alain , Boukheddaden Kamel , Lescouëzec Rodrigue
Published: June 2020

A key challenge in the design of magnetic molecular switches is to obtain bistability at room temperature. Here, we show that application of moderate pressure makes it possible to convert a paramagnetic FeIII2CoII2 square complex into a molecular switch exhibiting a full dia‐ to paramagnetic transition: FeIICoIII ⇔ FeIIICoII. Moreover, the complex follows a rare behavior: the higher the pressure, the broader the magnetic hysteresis. Thus, the application of an adequate pressure allows inducing a magnetic bistability at room temperature with predictable hysteresis width. The structural studies at different pressures suggest that the pressure‐enhanced bistability is due to the strengthening of intermolecular interactions upon pressure increase. An original microscopic Ising‐like model including pressure effects is developed to simulate this unprecedented behavior. Overall, this study shows that FeCo complexes could be very sensitive piezo switches with potential use as sensors.
Experimental and Computational Investigations of the Reactions between α,β‐Unsaturated Lactones and 1,3‐Dienes by Cooperative Lewis Acid/Brønsted Acid Catalysis
Authors: Weber Anja , Breugst Martin , Pietruszka Jörg
Published: June 2020

The reactions of α,β‐unsaturated δ‐lactones with activated dienes such as 1,3‐dimethoxy‐1‐[(trimethylsilyl)oxy]‐1,3‐butadiene (Brassard's diene) are barely known in literature and show high potential for the synthesis of isocoumarin moieties. An in‐depth investigation of this reaction proved a stepwise mechanism via the vinylogous Michael‐products. Subsequent cyclisation and oxidation by LHMDS and DDQ, respectively, provided six mellein derivatives (30–84 %) and four angelicoin derivatives (40–78 %) over three steps. DFT‐calculations provide insights into the reaction mechanism and support the theory of a stepwise reaction.
Biomimetic surface delivery of NGF and BDNF to enhance neurite outgrowth
Authors: Sandoval‐Castellanos Ana M. , Claeyssens Frederik , Haycock John W.
Published: June 2020

Treatment for peripheral nerve injuries includes the use of autografts and nerve guide conduits (NGCs). However, outcomes are limited, and full recovery is rarely achieved. The use of nerve scaffolds as a platform to surface immobilize neurotrophic factors and deliver locally is a promising approach to support neurite and nerve outgrowth after injury. We report on a bioactive surface using functional amine groups, to which heparin binds electrostatically. X‐ray photoelectron spectroscopy analysis was used to characterize the presence of nitrogen and sulfur. Nerve growth factor (NGF) and brain‐derived neurotrophic factor (BDNF) were bound by electrostatic interaction to heparin, and the release profile evaluated by enzyme‐linked immunosorbent assay, which showed that ca. 1% of NGF was released from each of the bioactive surface within 7 days. Furthermore, each surface showed a maximum release of 97% of BDNF. Neurotrophin release on neurite outgrowth was evaluated by primary dorsal root ganglion with a maximum neurite growth response in vitro of 1,075 µm detected for surfaces immobilized with NGF at 1 ng/ml. In summary, the study reports on the design and construction of a biomimetic platform to deliver NGF and BDNF using physiologically low concentrations of neurotrophin. The platform is directly applicable and scalable for improving the regenerative ability of existing NGCs and scaffolds.
Bioprocess development for scalable production of cultivated meat
Authors: Hanga Mariana P. , Ali Junaid , Moutsatsou Panagiota , de la Raga Fritz A. , Hewitt Christopher J. , Nienow Alvin , Wall Ivan
Published: June 2020

Traditional farm‐based products based on livestock are one of the main contributors to greenhouse gas emissions. Cultivated meat is an alternative that mimics animal meat, being produced in a bioreactor under controlled conditions rather than through the slaughtering of animals. The first step in the production of cultivated meat is the generation of sufficient reserves of starting cells. In this study, bovine adipose‐derived stem cells (bASCs) were used as starting cells due to their ability to differentiate towards both fat and muscle, two cell types found in meat. A bioprocess for the expansion of these cells on microcarriers in spinner flasks was developed. Different cell seeding densities (1,500, 3,000, and 6,000 cells/cm2) and feeding strategies (80%, 65%, 50%, and combined 80%/50% medium exchanges) were investigated. Cell characterization was assessed pre‐ and postbioprocessing to ensure that bioprocessing did not negatively affect bASC quality. The best growth was obtained with the lowest cell seeding density (1,500 cells/cm2) with an 80% medium exchange performed (p < .0001) which yielded a 28‐fold expansion. The ability to differentiate towards adipogenic, osteogenic, and chondrogenic lineages was retained postbioprocessing and no significant difference (p > .5) was found in clonogenicity pre‐ or postbioprocessing in any of the feeding regimes tested.
Virus harvesting in perfusion culture: Choosing the right type of hollow fiber membrane
Authors: Nikolay Alexander , de Grooth Joris , Genzel Yvonne , Wood Jeffery A. , Reichl Udo
Published: June 2020

The use of bioreactors coupled to membrane‐based perfusion systems enables very high cell and product concentrations in vaccine and viral vector manufacturing. Many virus particles, however, are not stable and either lose their infectivity or physically degrade resulting in significant product losses if not harvested continuously. Even hollow fiber membranes with a nominal pore size of 0.2 µm can retain much smaller virions within a bioreactor. Here, we report on a systematic study to characterize structural and physicochemical membrane properties with respect to filter fouling and harvesting of yellow fever virus (YFV; ~50 nm). In tangential flow filtration perfusion experiments, we observed that YFV retention was only marginally determined by nominal but by effective pore sizes depending on filter fouling. Evaluation of scanning electron microscope images indicated that filter fouling can be reduced significantly by choosing membranes with (i) a flat inner surface (low boundary layer thickness), (ii) a smooth material structure (reduced deposition), (iii) a high porosity (high transmembrane flux), (iv) a distinct pore size distribution (well‐defined pore selectivity), and (v) an increased fiber wall thickness (larger effective surface area). Lowest filter fouling was observed with polysulfone (PS) membranes. While the use of a small‐pore PS membrane (0.08 µm) allowed to fully retain YFV within the bioreactor, continuous product harvesting was achieved with the large‐pore PS membrane (0.34 µm). Due to the low protein rejection of the latter, this membrane type could also be of interest for other applications, that is, recombinant protein production in perfusion cultures.
The value relevance of corporate financial and nonfinancial information provided by the integrated report: A systematic review
Authors: Veltri Stefania , Silvestri Antonella
Published: June 2020

The integrated report (IR) is a new reporting tool connecting financial and nonfinancial information, in one report. The aim of IR is to present the firm's value creation over time. In recent years, IR has received both increasing academic and professional interest. Recent researches have focused on the potentialities (and criticalities) of IR and on its determinants, while there is a dearth of studies examining the value relevance of the information disclosed through IR for investors. Furthermore, in the literature, there are two competing views on IR usefulness for investors, one positing IR as beneficial, the other, detrimental to investors. Our study intends to contribute to the existing literature by systematically reviewing the empirical studies conducted until now in a thorough and unbiased manner, allowing more general conclusions to be drawn about the phenomenon than is possible from individual studies and to give some insights for further research activities.
C Tutor usage in relation to student achievement and progress: A study of introductory programming courses in Portugal and Serbia
Authors: Alves Luís , Gajić Dušan , Rangel Henriques Pedro , Ivančević Vladimir , Ivković Vladimir , Lalić Maksim , Luković Ivan , Varanda Pereira Maria João , Popov Srđan , Correia Tavares Paula
Published: June 2020

Previous research studies on introductory programming courses in engineering education in Portugal and Serbia have indicated that although high motivation and high expectations seem to be reported by students, many students may fail the course. This prompted a further inquiry into student attitudes, behavior, and achievement, and it also led to the introduction of C Tutor, a widely known program visualization tool, into courses in both countries. As a result, in the present study, self‐reported student achievement (grades), self‐reported student progress (knowledge improvement and confidence), and self‐reported usage and helpfulness of C Tutor were investigated. Anonymous data about students and their experience in the course, which also included the usage of C Tutor, were collected in a survey in Portugal and Serbia. Quantitative methods, including descriptive statistics, clustering, statistical testing of independence, and partial correlation analysis, were applied in analyses of survey data. The distribution of grades differed between the two countries, but overall attitudes were similar. Various uncovered patterns involving student attitudes and usage of C Tutor may serve as a starting point for new research studies.
Evaluation of the Period of PURPLE Crying: An Abusive Head Trauma Prevention Programme
Authors: Groisberg Shaina , Hashmi S. Shahrukh , Girardet Rebecca
Published: June 2020

Abusive head trauma (AHT) in infants is thought to be triggered by caregiver frustration with persistent crying. The Period of PURPLE Crying (POPC) is designed to educate parents about normal infant crying, strategies to use when infants cry and the dangers of shaking in an effort to decrease AHT. Studies evaluating the POPC have measured changes in parent knowledge and behaviour regarding infant crying. Our objective was to evaluate the POPC's effect on caregiver frustration with infant crying compared to standard discharge information (SDI). We taught paediatric interns and medical students rotating in the newborn nursery to deliver the POPC and discuss infant crying. New parents were pseudo‐randomised to receive SDI or the POPC plus SDI. Parents were contacted five‐to‐eight weeks after discharge and asked knowledge questions about infant crying as well as the number of times that they were frustrated by their infant's crying in the preceding week. Of 271 parents who consented to participate, 164 (61%) completed the survey. The POPC group answered two of the knowledge questions correctly more often than the control group (score differences: 17%, 95% confidence interval (CI) 3–32% and 21%, 95% CI 7–36%). However, parents reported frustration due to infant crying at similar rates between the control (55/80, 69%) and POPC (60/84, 71%) groups. Our results support previous findings that the POPC improves caregiver knowledge concerning infant crying. The POPC does not appear to affect caregiver frustration with crying.

‘Our objective was to evaluate the POPC's effect on caregiver frustration with infant crying compared to standard discharge information’

Key Practitioner Messages

Instructing new parents about normal infant crying and the dangers of shaking an infant remains an important part of anticipatory guidance.

The POPC is not more effective at reducing caregiver frustration with infant crying than standard discharge instructions.

Future investigations should specifically aim to include male caregivers as recipients of the programme.
Incidence and Risk Factors for Abusive Head Trauma: A Population‐Based Study
Authors: Rebbe Rebecca , Mienko Joseph A. , Martinson Melissa L.
Published: June 2020

Previous studies of abusive head trauma (AHT) suggest that incidence may vary by geographic location, and there is limited information regarding population‐based risk factors for this form of child maltreatment. This study provides new knowledge regarding these two aspects using the population of the US State of Washington born between 1999 and 2013. We used a linked administrative dataset comprising birth, hospital discharge, child protective services (CPS) and death records to identify the scale and risk factors for AHT for the state population using quantitative survival methods. We identified AHT using diagnostic codes in hospital discharge records defined by the US Centers for Disease Control and Prevention. A total of 354 AHT hospitalisations were identified, and the incidence for the state was 22.8 per 100 000 children under the age of one. Over 10 per cent of these children died. Risk factors included a teenaged mother at the time of birth, births paid for using public insurance, a child's low birth weight and maternal Native American race. The strongest risk factor was a prior CPS allegation, a similar finding to a California study of injury mortality. The practice and policy implications of these findings are discussed.

Key Practitioner Messages

A prior CPS report is a risk factor for AHT, regardless of the findings of the CPS report.

Two peaks of AHT were found, one at two months and another at eight months.

Prevention programming can target sociodemographic information available on birth records including teenaged mothers, low birth weight and births paid for with public insurance.
Benefit of a staged in‐hospital revascularization strategy in hemodynamically stable patients with ST‐segment elevation myocardial infarction and multivessel disease: Analyses by risk stratification
Authors: Kim Min Chul , Bae SungA , Ahn Youngkeun , Sim Doo Sun , Hong Young Joon , Kim Ju Han , Jeong Myung Ho , Kim Hyo‐Soo , Chae Shung Chull , Cha Kwang Soo ,   Other Korea Acute Myocardial Infarction Registry Investigators
Published: June 2020

Aims

The proper timing and indication of revascularization for a non‐culprit artery in patients with ST‐segment elevation myocardial infarction (STEMI) and multivessel disease (MVD) without cardiogenic shock remains controversial.

Methods and Results

This multicenter study included patients with STEMI and MVD without cardiogenic shock. Data were analyzed at 3 years according to the percutaneous coronary intervention (PCI) strategy: immediate multivessel revascularization (MVR) (n = 351), stepwise MVR (n = 510), and culprit‐only PCI (n = 1,142). The primary outcome was all‐cause mortality. The stepwise MVR group had a lower risk of all‐cause death. The results were consistent after multivariate regression, propensity‐score matching, inverse probability weighting, and Bayesian proportional hazards modeling. In subgroup analyses stratified by the Global Registry of Acute Coronary Events score, stepwise MVR also lowered the risk of all‐cause death compared to culprit‐only PCI and immediate MVR in high risk patients but not in patients at low to intermediate risk.

Conclusions

In patients with STEMI and MVD without cardiogenic shock, in‐hospital stepwise MVR was associated with a lower risk of all‐cause death than culprit‐only PCI or immediate MVR, particularly in the high‐risk subgroup.
First case report: Late‐onset coronary artery spasm after radiofrequency catheter ablation for atrial fibrillation in a Caucasian patient
Authors: Tsushima Takahiro , Osman Mohammed Najeeb , Josephson Richard A. , Thal Sergio G.
Published: June 2020

Most of the coronary vasospasms were found intraprocedurally, and it is very rare to see late‐onset vasospasms that happened a few hours after uncomplicated ablations. The recognition of this rare but potentially life‐threatening complication is important to improve the conventional practice of catheter ablation for patients with drug‐refractory atrial fibrillation.
Advances in the Synthesis of Imine‐Containing Azaarene Derivatives via Photoredox Catalysis
Authors: Yin Yanli , Zhao Xiaowei , Jiang Zhiyong
Published: June 2020

Abundant and structurally diverse nitrogen‐containing aromatic heterocycles (azaarenes) are of great importance in many scientific and industrial fields. The development of methods for accessing azaarene derivatives has thus attracted substantial attention from chemists. In particular, directly exploiting the electronic properties of azaarenes to trigger transformations of azaarene‐containing substrates has long been appreciated as a powerful tool because it avoids the use of extra activating groups and allows the straightforward functionalization of azaarenes. In recent years, numerous advances have been made in the synthesis of imine‐containing azaarene derivatives under photoredox catalysis; the unique electronic and structural properties of these azaarenes as well as highly reactive and non‐traditional radical‐based process have inspired a number of targeted strategies and the corresponding efficient methodologies. In view of the currently available reviews, here, we will discuss the advances in the strategies of using these azaarenes as analogues of carbonyls and as single‐electron oxidants from the first example to the present.
Oxygen Electrocatalysis with Mesoporous Co−N−C Catalysts: Towards Understanding the Active Site and Development of Rechargeable Zn‐Air Batteries
Authors: Samanta Arpan , Raj C. Retna
Published: June 2020

We demonstrate the synthesis of two bifunctional electrocatalysts (Co−N−C‐TET and Co−N−C‐Phen) based on cobalt‐ and nitrogen‐doped mesoporous carbon derived from cobalt complexes and their bifunctional electrocatalytic activity towards oxygen electrocatalysis. Both catalysts are bifunctionally active towards the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) in alkaline pH. Co−N−C‐TET has excellent OER activity and delivers the benchmark current density of 10 mA cm−2 at a remarkably low overpotential of 0.28 V. The Co−N−C‐Phen catalyst is superior in terms of overall bifunctional activity and durability. The nitrogen and cobalt content of the catalyst controls the overall oxygen electrocatalytic performance. The nitrogen content, and its chemical nature in the catalyst, decides the ORR activity, whereas the metal content of the catalyst regulates the OER activity. Cobalt‐rich Co−N−C‐TET has significantly high OER activity compared to Co−N−C‐Phen. The enhanced OER activity of the Co−N−C‐TET catalyst is ascribed to the presence of a high cobalt content. The graphitic‐N‐ and pyridinic‐N‐rich Co−N−C‐Phen catalyst has enhanced ORR activity. An aqueous rechargeable Zn‐air battery (ZAB) is fabricated using the Co−N−C‐Phen‐based air‐cathode. The ZAB shows an open‐circuit voltage of 1.40 V and power density of 128.2 mW cm−2 with >48 h of galvanostatic charge‐discharge cycling stability. It outperforms the reference ZAB made of Pt and IrO2 catalysts.
Tuning the Triplet Excited State of Bis(dipyrrin) Zinc(II) Complexes: Symmetry Breaking Charge Transfer Architecture with Exceptionally Long Lived Triplet State for Upconversion
Authors: Mahmood Zafar , Rehmat Noreen , Ji Shaomin , Zhao Jianzhang , Sun Shanshan , Di Donato Mariangela , Li Mingde , Teddei Maria , Huo Yanping
Published: June 2020

Zinc(II) bis(dipyrrin) complexes, which feature intense visible absorption and efficient symmetry breaking charge transfer (SBCT) are outstanding candidates for photovoltaics but their short lived triplet states limit applications in several areas. Herein we demonstrate that triplet excited state dynamics of bis(dipyrrin) complexes can be efficiently tuned by attaching electron donating aryl moieties at the 5,5′‐position of the complexes. For the first time, a long lived triplet excited state (τT=296 μs) along with efficient ISC ability (ΦΔ=71 %) was observed for zinc(II) bis(dipyrrin) complexes, formed via SBCT. The results revealed that molecular geometry and energy gap between the charge transfer (CT) state and triplet energy levels strongly control the triplet excited state properties of the complexes. An efficient triplet–triplet annihilation upconversion system was devised for the first time using a SBCT architecture as triplet photosensitizer, reaching a high upconversion quantum yield of 6.2 %. Our findings provide a blueprint for the development of triplet photosensitizers based on earth abundant metal complexes with long lived triplet state for revolutionary photochemical applications.
Intermacrocyclic Interactions upon Stepwise Oxidations in a Monometallic Porphyrin Dimer: Ring versus Metal‐Center Oxidations and Effect of Counter Anions
Authors: Singh Akhil Kumar , Rath Sankar Prasad
Published: June 2020

The effect of intermacrocyclic interactions was studied by controlled and stepwise oxidations of a monometallic silver(II) porphyrin dimer that contains a highly flexible ethane bridge. Monometallic dimers are unique systems and behave differently from their dimetallic analogues on the basis of their available sites for storing oxidizing equivalents. UV‐visible spectrometry, 1H NMR spectroscopy, XPS and single crystal X‐ray diffraction studies clearly suggest the removal of the first electron from the metal center. The removal of the second electron occurred from the ring center to form a π‐cation radical and, thereby, form a very unique mixed‐valent species. However, unlike in all other ethane‐bridged metalloporphyrin dimers reported earlier, the 2e‐oxidized species showed quite unusual structures depending on the nature of counter ions. Ions, such as SbF6, SbCl6 and PF6, are engaged in strong interactions with the porphyrin π‐cation radical and causes substantial structural changes, including large deformation of the ring. The solid‐state structure remains intact in solution as well. The observations are further supported by DFT calculations.