bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of p‐WSe2/n‐Ge Heterojunctions for High‐Speed Broadband Photodetectors
Authors: Lee Chan Ho , Park Youngseo , Youn Sukhyeong , Yeom Min Jae , Kum Hyun S. , Chang Jiwon , Heo Junseok , Yoo Geonwook
Published: October 2021

Van der Waals (vdW) 2D/3D heterostructures are extensively studied for high‐performance photodetector applications. Until now, the type of 2D materials has been the primary area of interest rather than the design of 3D semiconductors. In this study, high‐speed broadband photodiodes (PDs) based on vdW p‐WSe2/n‐Ge heterojunctions are reported, and the performance compared with different n‐Ge regions formed via the ion‐implantation process. The fabricated PD with a typical long n‐Ge region and low doping concentration responds to a broad spectral range from visible to infrared near 1550 nm with a response time of ≈3 µs and responsivity of 1.3 A W−1. The inferior responsivity of PDs with short n‐Ge regions can be improved as demonstrated by experimental results and process simulation. Density functional theory calculations are performed to estimate the variation of the energy band structures with the doping concentration of n‐Ge. Fast photoresponse and efficient carrier separation across the heterojunction can be expected regardless of the n‐Ge doping concentration. Based on the experimental results together with theoretical band structure and process simulation, it is shown that the heterojunction with an optimized n‐Ge design is a promising high‐speed broadband photodetector that can be implemented with complementary metal‐oxide‐semiconductor design and fabrication processes.
Molecularly Tailored Interface for Long‐Term Xenogeneic Cell Transplantation
Authors: Madhurakkat Perikamana Sajeesh Kumar , Seale Nailah , Hoque Jiaul , Ryu Ji Hyun , Kumar Vardhman , Shih Yuru Vernon , Varghese Shyni
Published: October 2021

Encapsulation of therapeutic cells in a semipermeable device can mitigate the need for systemic immune suppression following cell transplantation by providing local immunoprotection while being permeable to nutrients, oxygen, and different cell‐secreted biomolecules. However, fibrotic tissue deposition around the device has been shown to compromise the long‐term function of the transplanted cells. Herein, a macroencapsulation device design that improves long‐term survival and function of the transplanted cells is reported. The device is comprised of a semipermeable chitosan pouch with a tunable reservoir and molecularly engineered interface. The chitosan pouch interface decorated with 1,12‐dodecanedioic acid (DDA), limits the cell adhesion and vigorous foreign body response while maintaining the barrier properties amenable to cell encapsulation. The device provides long‐term protection to the encapsulated human primary hepatocytes in the subcutaneous space of immunocompetent mice. The device supports the encapsulated cells for up to 6 months as evident from cell viability and presence of human specific albumin in circulation. Solutions that integrate biomaterials and interfacial engineering such as the one described here may advance development of easy‐to manufacture and retrievable devices for the transplantation of therapeutic cells in the absence of immunosuppression.
Machine Learning‐Driven Biomaterials Evolution
Authors: Suwardi Ady , Wang FuKe , Xue Kun , Han Ming‐Yong , Teo Peili , Wang Pei , Wang Shijie , Liu Ye , Ye Enyi , Li Zibiao , Loh Xian Jun
Published: October 2021

Biomaterials is an exciting and dynamic field, which uses a collection of diverse materials to achieve desired biological responses. While there is constant evolution and innovation in materials with time, biomaterials research has been hampered by the relatively long development period required. In recent years, driven by the need to accelerate materials development, the applications of machine learning in materials science has progressed in leaps and bounds. The combination of machine learning with high‐throughput theoretical predictions and high‐throughput experiments (HTE) has shifted the traditional Edisonian (trial and error) paradigm to a data‐driven paradigm. In this review, each type of biomaterial and their key properties and use cases are systematically discussed, followed by how machine learning can be applied in the development and design process. The discussions are classified according to various types of materials used including polymers, metals, ceramics, and nanomaterials, and implants using additive manufacturing. Last, the current gaps and potential of machine learning to further aid biomaterials discovery and application are also discussed.
Dual‐Single‐Atom Tailoring with Bifunctional Integration for High‐Performance CO2 Photoreduction
Authors: Cheng Lei , Yue Xiaoyang , Wang Linxi , Zhang Dainan , Zhang Peng , Fan Jiajie , Xiang Quanjun
Published: October 2021

Single‐atom photocatalysis has been demonstrated as a novel strategy to promote heterogeneous reactions. There is a diversity of monoatomic metal species with specific functions; however, integrating representative merits into dual‐single‐atoms and regulating cooperative photocatalysis remain a pressing challenge. For dual‐single‐atom catalysts, enhanced photocatalytic activity would be realized through integrating bifunctional properties and tuning the synergistic effect. Herein, dual‐single‐atoms supported on conjugated porous carbon nitride polymer are developed for effective photocatalytic CO2 reduction, featuring the function of cobalt (Co) and ruthenium (Ru). A series of in situ characterizations and theoretical calculations are conducted for quantitative analysis of structure–performance correlation. It is concluded that the active Co sites facilitate dynamic charge transfer, while the Ru sites promote selective CO2 surface‐bound interaction during CO2 photoreduction. The combination of atom‐specific traits and the synergy between Co and Ru lead to the high photocatalytic CO2 conversion with corresponding apparent quantum efficiency (AQE) of 2.8% at 385 nm, along with a high turnover number (TON) of more than 200 without addition of any sacrificial agent. This work presents an example of identifying the roles of different single‐atom metals and regulating the synergy, where the two metals with unique properties collaborate to further boost the photocatalytic performance.
Photoinduced Halide Segregation in Ruddlesden–Popper 2D Mixed Halide Perovskite Films
Authors: Cho Junsang , Mathew Preethi S. , DuBose Jeffrey T. , Kamat Prashant V.
Published: October 2021

2D lead halide perovskites, which exhibit bandgap tunability and increased chemical stability, have been found to be useful for designing optoelectronic devices. Reducing dimensionality with decreasing number of layers (n = 10–1) also imparts resistance to light‐induced ion migration as seen from the halide ion segregation and dark recovery in mixed halide (Br:I = 50:50) perovskite films. The light‐induced halide ion segregation efficiency, as determined from difference absorbance spectra, decreases from 20% to <1% as the dimensionality is decreased for 2D perovskite film from n = 10 to 1. The segregation rate constant (ksegregation), which decreases from 5.9 × 10−3 s−1 (n = 10) to 3.6 × 10−4 s−1 (n = 1), correlates well with nearly an order of magnitude decrease observed in charge‐carrier lifetime (τaverage = 233 ps for n = 10 vs τavg = 27 ps for n = 1). The tightly bound excitons in 2D perovskites make charge separation less probable, which in turn decreases the halide mobility and resulting phase segregation. The importance of controlling the dimensionality of the 2D architecture in suppressing halide ion mobility is discussed.
Intrinsic Linear Dichroism of Organic Single Crystals toward High‐Performance Polarization‐Sensitive Photodetectors
Authors: Wang Tianyu , Zhao Kai , Wang Pan , Shen Wanfu , Gao Haikuo , Qin Zhengsheng , Wang Yongshuai , Li Chunlei , Deng Huixiong , Hu Chunguang , Jiang Lang , Dong Huanli , Wei Zhongming , Li Liqiang , Hu Wenping
Published: October 2021

The ability to detect light in photodetectors is central to practical optoelectronic applications, which has been demonstrated in inorganic semiconductor devices. However, so far, the study of polarization‐sensitive organic photodetectors, which have unique applications in flexible and wearable electronics, has not received much attention. Herein, the construction of polarization‐sensitive photodetectors based on the single crystals of a superior optoelectronic organic semiconductor, 2,6‐diphenyl anthracene (DPA), is demonstrated. The systematic characterization of two‐dimensionally grown DPA crystals with various techniques definitely show their strong anisotropy in molecular vibration, optical reflectance and optical absorption. In terms of polarization sensitivity, DPA‐crystal based photodetectors exhibit a linear dichroic ratio up to ≈1.9. Theoretical calculations confirm that intrinsic linear dichroism, originated from the anisotropic in‐plane crystal structure, is responsible for the polarization sensitivity of DPA crystals. This work opens up a new door for exploiting organic semiconductors for developing highly compact polarization photodetectors and providing new functionalities in novel flexible optical and optoelectronic applications.
Developing the Nondevelopable: Creating Curved‐Surface Electronics from Nonstretchable Devices
Authors: Rich Steven I. , Lee Shinyoung , Fukuda Kenjiro , Someya Takao
Published: October 2021

The incorporation of electronics onto curved surfaces promises to bring new levels of intelligence to the ergonomic, aesthetic, aerodynamic, and optical surfaces that are ever‐present in our lives. However, since many of these surfaces have 2D (i.e., nondevelopable) curvature, they cannot be formed from the deformation of a flat, nonstretchable sheet. This means that curved electronics cannot capitalize on the rapid technological advances taking place in the field of ultrathin electronics, since ultrathin devices, though ultraflexible, are not stretchable. In this work, a shrink‐based paradigm is presented to apply such thin‐film electronics to nondevelopable surfaces, expanding the capabilities of current nondevelopable electronics, and linking future developments in thin‐film technology to similar developments in curved devices. The wrinkling of parylene‐based devices and the effects of shrinkage on common electrical components are examined, culminating in shrinkable touch sensors and organic photovoltaics, laminated to various nondevelopable surfaces without loss of performance.
The Importance of Surface Adsorbates in Solution‐Processed Thermoelectric Materials: The Case of SnSe
Authors: Liu Yu , Calcabrini Mariano , Yu Yuan , Genç Aziz , Chang Cheng , Costanzo Tommaso , Kleinhanns Tobias , Lee Seungho , Llorca Jordi , Cojocaru‐Mirédin Oana , Ibáñez Maria
Published: October 2021

Solution synthesis of particles emerges as an alternative to prepare thermoelectric materials with less demanding processing conditions than conventional solid‐state synthetic methods. However, solution synthesis generally involves the presence of additional molecules or ions belonging to the precursors or added to enable solubility and/or regulate nucleation and growth. These molecules or ions can end up in the particles as surface adsorbates and interfere in the material properties. This work demonstrates that ionic adsorbates, in particular Na+ ions, are electrostatically adsorbed in SnSe particles synthesized in water and play a crucial role not only in directing the material nano/microstructure but also in determining the transport properties of the consolidated material. In dense pellets prepared by sintering SnSe particles, Na remains within the crystal lattice as dopant, in dislocations, precipitates, and forming grain boundary complexions. These results highlight the importance of considering all the possible unintentional impurities to establish proper structure–property relationships and control material properties in solution‐processed thermoelectric materials.
Topotactic Electrochromism for Efficient Coloration Applications
Authors: Nguyen Hien Thi Dieu , Zhang Dawei , Nguyen Triet Minh , Zhang Haoze , Seidel Jan
Published: October 2021

Topotactic transitions, that is, reversible crystal structure changes due to controllable stoichiometry of material, offer substantial potential to control a wide variety of functionality in transition metal oxides, especially in systems with high ionic mobility and correlated electrons. Here the authors report on topotactic electrochromism with prominent coloration efficiency in SrCo0.66Fe0.34O3−δ associated with changes of electrical conductivity and electronic structure of the material. Changes in electron correlation lead to significant coloration and light absorption, which provides a general approach for utilizing topotactic transitions in electrochromic applications.
Metasurface‐Enhanced Photon Upconversion upon 1550 nm Excitation
Authors: Ahiboz Doğuşcan , Andresen Elina , Manley Phillip , Resch‐Genger Ute , Würth Christian , Becker Christiane
Published: October 2021

Photon upconversion upon 1550 nm excitation is of high relevance for applications in the third biological excitation window, for photovoltaics beyond current limitations, and enables appealing options in the field of glass fiber telecommunications. Trivalent doped erbium ions (Er3+) are the material of choice for 1550 nm excited upconversion, however, they suffer from a low absorption cross‐section and a low brightness. Therefore, the ability of silicon metasurfaces to provide greatly enhanced electrical near‐fields is employed to enable efficient photon upconversion even at low external illumination conditions. Hexagonally shaped β‐NaYF4:Er3+ nanoparticles are placed on large‐area silicon metasurfaces designed to convert near‐infrared (1550 nm) to visible light. More than 2400‐fold enhanced photon upconversion luminescence is achieved by using this metasurface instead of a planar substrate. With the aid of optical simulations based on the finite‐element method, this result is attributed to the coupling of the excitation source with metasurface resonances at appropriate incident angles. Analysis of the excitation power density dependence of upconversion luminescence and red‐to‐green‐emission ratios enables the estimation of nanoscale near‐field enhancement on the metasurface. The findings permit the significant reduction of required external excitation intensities for photon upconversion of 1550 nm light, opening perspectives in biophotonics, telecommunication, and photovoltaics.
Nonlinear Optical Properties and Ultrafast Carrier Dynamics of 2D Indium Selenide Nanosheets
Authors: Chen Chenduan , Dong Ningning , Huang Jiawei , Chen Xin , Wang Hongqiang , Wang Zixin , Wang Jun
Published: October 2021

This work reports the nonlinear optical properties and ultrafast carrier dynamics of indium selenide (InSe) nanosheets obtained via liquid‐phase exfoliation under pulsed excitation with different durations. InSe nanosheets exhibit a better saturable absorption response under 6 ns pulse excitation than that under 380 fs excitation. In addition, the scattering phenomena of InSe dispersions with different mechanisms under various pulse durations are discovered, which are caused by the thermal effect under ns pulse excitation and dynamic spatial self‐phase modulation affected by laser streaming under fs pulse excitation. The pump‐probe measurements reveal that the InSe dispersion has ultrafast saturable absorption and photoinduced absorption processes, which may be caused by free carrier absorption or bandgap renormalization.
Wide‐Gamut Blended Conjugated Polymer Microspheres
Authors: Zhang Lijuan , Mehreen Tanisha , Liu Xiaoyuan , Kumar Vishal , Vagin Sergey , Gardner Kirsty , Wang Hui , Sun Xuejun , Wu Shaoyi , Rieger Bernhard , Meldrum Alkiviathes
Published: October 2021

Conjugated polymers (CPs) can potentially provide an alternative to conventional fluorescent microsphere technologies; however, examples of CP microspheres encompassing an extensive range of sizes are few, and wide‐ranging spectral control, as needed for many applications, has never been demonstrated. Blended CP microspheres consisting of individual polymers are synthesized here. They are blended to have widely separated Commission Internationale de l'Éclairage (CIE) color coordinates and a compatible synthesis while at the same time forming well‐defined domain structures. By developing appropriate mixtures of selected blue, green, and red fluorescent CPs, blended CP microspheres are demonstrated to cover an extensive range of color coordinates including white. It is shown that multi‐CP microspheres with core–shell or related structures can provide optimum characteristics, while energy and/or charge transfer in finer mixtures result in microspheres without the desired emission properties. Pre‐ or postprocessing further directs consistent changes in the CP microspheres that ultimately regulate the overall spectral response. This approach can lead to a new class of bright fluorescent microparticles with applications in a wide range of disciplines that demand maximum brightness and highly specific emission spectra.
Recyclable, Immobilized Transition‐Metal Photocatalysts
Authors: Abramov Alex , Bonardd Sebastián , Pérez‐Ruiz Raúl , Díaz Díaz David
Published: October 2021

The use of transition‐metal complexes as photocatalysts have allowed the performance of diverse organic transformations in an outstanding manner, characterized not only by high yields, TOF, and selectivity values, but also by modulating and providing access to novel molecular structures that, without them, would be difficult if not impossible. However, one of the biggest concerns regarding the use of these photocatalysts relies on the difficulties associated with their isolation from reaction media and reutilization once the chemical process ends. The above, besides contaminating reaction products and requiring out tedious purification processes, prompts the inevitable loss of the catalyst, directly affecting its recyclability. In addition, this situation results in negative outcomes from an economic and environmental perspective, since transition‐metal complexes are usually expensive materials, and their unsuccessful recovery could result in leakage into the environment. These drawbacks served as inspiration for the elaboration of the present review focused on the development of novel strategies developed during the last decade for the successful recovery of these species. The strategies summarized herein, whether for homogeneous or heterogeneous systems, are based on the use of thermotropic solvents, changes in the hydrophilic balance of the catalyst, the employment of polymers, copolymers, porous macromolecular structures, and inorganic nanostructures as support of these entities. Moreover, the use of organized and confining media, such as micelles and gels in this context, is also discussed. We hope that this review will motivate the search for new strategies to develop novel catalytic systems, understanding that high performance is based not only on yields but also on recyclability, sustainability, and responsibility to the environment.

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Spin‐Dependent Electronic Structure and Magnetic Properties of 2D JANUS Mn2CFCl/CuBiP2Se6 Van Der Waals Multiferroic Heterostructures
Authors: Fu Luqian , Wang Xiaocha , Mi Wenbo
Published: October 2021

2D van der Waals (vdW) multiferroic heterostructures have potential applications in novel 2D spintronic devices. Here, the electronic structure and magnetic anisotropy of 2D vdW multiferroic Mn2CFCl/CuBiP2Se6 heterostructures are investigated systematically by first‐principles calculations. Ferroelectric material CuBiP2Se6 has a built‐in electric field. Mn2CFCl is a half‐metallicity with ferromagnetic. The plane average potential difference of Mn2CFCl/CuBiP2Se6 heterostructures is 0.02 eV in P↓ state and 0.39 eV in P↑ state. The magnetic anisotropy of P↑ and P↓ states is shown perpendicular magnetic anisotropy (PMA). The P↑ state exhibits metallic character with the biaxial strain of 4%, −6%, while the P↓ state demonstrates half‐metallicity at a strain of 2%, 4%, 6%. The P↑ state shows PMA at the different biaxial strain. However, the P↓ state shows PMA at biaxial strain of −2%, −4%, and 6%, which shifts PMA to in‐plane magnetic anisotropy at −6%, 2%, and 4%. These tunable electronic structure and magnetic anisotropy suggest that the 2D multiferroic Mn2CFCl/CuBiP2Se6 vdW heterostructures have potential applications in spintronic devices.
Sulfurization Engineering of One‐Step Low‐Temperature MoS2 and WS2 Thin Films for Memristor Device Applications
Authors: Gu Yuqian , Serna Martha I. , Mohan Sivasakthya , Londoño‐Calderon Alejandra , Ahmed Taimur , Huang Yifu , Lee Jack , Walia Sumeet , Pettes Michael T. , Liechti Kenneth M. , Akinwande Deji
Published: October 2021

2D materials have been of considerable interest as new materials for device applications. Non‐volatile resistive switching applications of MoS2 and WS2 have been previously demonstrated; however, these applications are dramatically limited by high temperatures and extended times needed for the large‐area synthesis of 2D materials on crystalline substrates. The experimental results demonstrate a one‐step sulfurization method to synthesize MoS2 and WS2 at 550 °C in 15 min on sapphire wafers. Furthermore, a large area transfer of the synthesized thin films to SiO2/Si substrates is achieved. Following this, MoS2 and WS2 memristors are fabricated that exhibit stable non‐volatile switching and a satisfactory large on/off current ratio (103–105) with good uniformity. Tuning the sulfurization parameters (temperature and metal precursor thickness) is found to be a straightforward and effective strategy to improve the performance of the memristors. The demonstration of large‐scale MoS2 and WS2 memristors with a one‐step low‐temperature sulfurization method with simple strategy to tuning can lead to potential applications such as flexible memory and neuromorphic computing.
Cubic Spinel XIn2S4 (X = Fe, Co, Mn): A New Type of Anode Material for Superfast and Ultrastable Na‐Ion Storage
Authors: Yan Dong , Li Ke , Yan Yaping , Huang Shaozhuan , Von Lim Yew , Shang Yang , Fang Daliang , Ang Lay Kee , Yang Hui Ying
Published: October 2021

Bimetallic sulfides are prospective candidates as Na‐ion battery (NIB) anodes owing to their abundant redox active sites and high specific capacities, while the rate and cycling performances are limited due to their severe mechanical strain and sluggish reaction kinetics. Herein, for the first time, a series of cubic spinel XIn2S4 (X = Fe, Co, Mn) anodes is proposed for superfast and ultrastable Na‐ion storage. The FeIn2S4 delivers the best electrochemical performance among them with the amazing results especially for its superfast charging (9–13 s per charge with ≈300 mAh g−1 input) and ultrastable cycling capabilities (25 K cycles with ultralow 0.000801% capacity loss per cycle). Further density functional theory calculations and experimental results indicate that Fe substitution at tetrahedral sites of cubic spinel In2.77S4 can significantly enhance its electrical conductivity, Na‐ion binding kinetics, and pseudocapacitive contributions, reduce its Na‐ion diffusion barrier, and relieve its mechanical strain. Moreover, the inherent In skeleton at octahedral sites can induce a complementary reaction to stabilize the conversion‐type Fe‐based components. Furthermore, the FeIn2S4‐based full cells with excellent electrochemical performance are assembled. This work demonstrates the feasibility of enhancing the synergies within bimetallic sulfides to realize remarkable electrochemical performance.
Rapid‐cycle deliberate practice improves time to defibrillation and reduces workload: A randomized controlled trial of simulation‐based education
Authors: Lemke Daniel S. , Young Ann L , Won Sharon K. , Rus Marideth C. , Villareal Nadia N. , Camp Elizabeth A. , Doughty Cara
Published: October 2021

Background

The optimal structure of simulation to train teams to perform pediatric advanced life support (PALS) requires further research. Most simulation is structured with an uninterrupted scenario with postsimulation debriefing (PSD). Rapid‐cycle deliberate practice (RCDP) is structured with a series of simulations with microdebriefing quickly switching within action targeting specific performance goals.

Objective

The objective was to compare team performance immediately after training, as well as learner workload, for teams trained using either PSD or RCDP.

Methods

In 2018–2019, a total of 41 interprofessional teams of 210 residents and nurses were recruited from 250 eligible participants (84%) and randomized into either arm (RCDP or PSD) teaching the same objectives of resuscitation of a patient in PEA arrest, in the same time frame. The structure of the simulation varied. Demographic surveys were collected before training, the National Aeronautics and Space Administration‐Task Load Index (NASA‐TLX) was administered immediately after training to assess workload during training and performance was assessed immediately after training using a pulseless ventricular tachycardia arrest with the primary outcome being time to defibrillation.

Results

Thirty‐nine teams participated over a 16‐month time span. Performance of teams randomized to RCDP showed significantly better time to defibrillation, 100 s (95% confidence interval [CI] = 90–111), compared to PSD groups, 163 s (95% CI = 120–201). The workload of the groups also showed a lower total NASA‐TLX score for the RCDP groups.

Conclusions

For team‐based time‐sensitive training of PALS, RCDP outperformed PSD. This may be due to a reduction in the workload faced by teams during training.
Selective forces on the maintenance of outcrossing in an almost exclusively cleistogamous violet species
Authors: Seguí Jaume , Hervías‐Parejo Sandra , Traveset Anna
Published: October 2021

Premise

Cleistogamous species constitute interesting study systems to resolve the longstanding question of how outcrossing is maintained given that seed production is ensured through selfing. In this work, we investigate the selective forces that allow the persistence of producing self‐pollinated cleistogamous (CL) and chasmogamous (CH) flowers inViola jaubertianaMarès & Vigin.

Methods

We monitored three populations at different elevation for two years, and studied the flowering phenology and the relative contribution of each flower morph to parental fitness. We tested whether allocation to CH and CL flowers differed across populations and if it covaried with herbivory and water stress conditions. We also performed hand‐pollination and bagging experiments in CH flowers to estimate inbreeding depression and heterosis.

Results

The CH flowers open in winter under unfavorable conditions for pollination, show high pollen limitation and no‐delayed selfing, and thus produce a low amount of seeds. Conversely, CL flowers appear in early spring, are physiologically cheaper to produce (i.e., dry weight is 3.4 times lower than that of CH flowers), and yield approximately 100 times more seeds than CH flowers. The CH flowers were favored under water stress and low herbivory. Crosses between populations showed up to 25% greater fitness than those within populations.

Conclusions

Despite the great pollen limitation in CH flowers, we suggest that the interaction among different environmental determinants and heterosis are probably sufficient forces to maintain chasmogamy in this long‐lived species, reducing deleterious fixed mutations in the selfed lines.
Strain‐Induced Magnetism in MSi2N4 (M = V, Cr): A First‐Principles Study
Authors: Li Yingmei , Wang Jing , Yang Guochun , Liu Yong
Published: October 2021

The discovery of ferromagnetic 2D van der Waals (vdW) materials has opened up opportunities for exploring and harnessing magnetism in low‐dimensional limit, and developing innovative paper‐like spintronic devices. Stress engineering demonstrates unique advantages in regulating material properties, especially for 2D materials. With the aid of first‐principles calculations, the effectiveness of strain engineering for modulating the electronic and magnetic properties of MSi2N4 (M = V, Cr) monolayers from a new family of layer‐structured 2D vdW materials is explored. Their magnetic configurations are effectively tuned via the uniaxial and biaxial tensile strain of in‐plane lattice vectors. VSi2N4 exhibits half‐metallic ferromagnetic character, whereas CrSi2N4 is prone to be antiferromagnetic (AFM), which is rationalized from the competition between the direct metal–metal AFM interaction and the 900 ferromagnetic superexchange. More intriguingly, VSi2N4 demonstrates a high magnetic ordering temperature of 285 K, which is close to room temperature. The predicted appealing properties of VSi2N4 under strain await experimental confirmation.
Molybdän‐vermittelte N2‐Spaltung und Funktionalisierung in Gegenwart eines koordinierten Alkins
Authors: Wagner Hannah K. , Wadepohl Hubert , Ballmann Joachim
Published: October 2021

Es wird von einem neuen [PCCP]Mo‐Pincerkomplex mit einem koordinierten Alkin berichtet, der zur Spaltung von molekularem Stickstoff eingesetzt wurde. Das, im Liganden fixierte η2‐Alkin blieb während dieser Reduktion verschont. DFT‐Rechnungen deuten darauf hin, dass die Reaktion über einen zunächst generierten terminalen N2‐Komplex verläuft, der dann in ein di‐nukleares μ‐(η1:η1)‐N2‐verbrücktes Intermediat überführt wird, bevor es zum N−N‐Bindungsbruch kommt. Die Protonierung, Alkylierung und Acylierung des hierbei gebildeten Molybdännitrido‐Komplexes führte zu den entsprechenden N‐funktionalisierten Imido‐Komplexen. Im Zuge einer nachgelagerten Oxidation des N‐acylierten Imido‐Derivats in MeCN kam es zur C−C‐Kupplung von MeCN und zum Aufbau eines Fumaronitril‐Fragments, welches zwei Molybdänzentren verbrückt. Die wichtige Erkenntnis, dass die starke N≡N‐Bindung in Gegenwart einer schwächeren, aber entsprechend fixierten C≡C‐Bindung gespalten werden kann, widerspricht der weit verbreiteten Denkweise, dass koordinierte Alkine stets reaktiver sind als gasförmiger Stickstoff.
La3Ga3Ge2S3O10: An Ultraviolet Nonlinear Optical Oxysulfide Designed by Anion‐Directed Band Gap Engineering
Authors: Yan Hong , Matsushita Yoshitaka , Yamaura Kazunari , Tsujimoto Yoshihiro
Published: October 2021

Chalcogenide‐containing compounds have been widely studied as infrared nonlinear optical (NLO) materials. However, they have never been applied in the ultraviolet (UV) region owing to the high energy levels of chalcogen anions, leading to band gap narrowing. We report the synthesis of a new UV NLO oxysulfide La3Ga3Ge2S3O10 with an exceptionally wide band gap of 4.70 eV due to from the unique anion‐ordered frameworks comprising 1D 1∞[(Ga3/5Ge2/5)3S3O3] triangular tubes and 0D (Ga3/5Ge2/5)2O7 dimers of corner‐sharing (Ga/Ge)S2O2 and (Ga/Ge)O4 tetrahedra, respectively. Second harmonic generation (SHG) measurements revealed that La3Ga3Ge2S3O10 was phase matchable with twice the SHG response of KH2PO4. The results of theoretical calculations suggest that the strong SHG response is mainly attributable to the S‐3p and O‐2p orbitals in the occupied states. The anion‐directed band‐gap engineering may give insights into the application of NLO oxychalcogenides in the UV regions.
Molybdenum‐Mediated N2‐Splitting and Functionalization in the Presence of a Coordinated Alkyne
Authors: Wagner Hannah K. , Wadepohl Hubert , Ballmann Joachim
Published: October 2021

A new [PCCP]‐coordinated molybdenum platform comprising a coordinated alkyne was employed for the cleavage of molecular dinitrogen. The coordinated η2‐alkyne was left unaffected during this reduction. DFT calculations suggest that the reaction proceeds via an initially generated terminal N2‐complex, which is converted to a dinuclear μ‐(η1:η1)‐N2‐bridged intermediate prior to N−N bond cleavage. Protonation, alkylation and acylation of the resulting molybdenum nitrido complex led to the corresponding N‐functionalized imido complexes. Upon oxidation of the N‐acylated imido derivative in MeCN, a fumaronitrile fragment was built up via C−C coupling of MeCN to afford a dinuclear molybdenum complex. The key finding that the strong N≡N bond may be cleaved in the presence of a weaker, but spatially constrained C≡C bond contradicts the widespread paradigm that coordinated alkynes are in general more reactive than gaseous N2.
Taming the Lewis Superacidity of Non‐Planar Boranes: C−H Bond Activation and Non‐Classical Binding Modes at Boron
Authors: Osi Arnaud , Mahaut Damien , Tumanov Nikolay , Fusaro Luca , Wouters Johan , Champagne Benoît , Chardon Aurélien , Berionni Guillaume
Published: October 2021

The rational design of a geometrically constrained boron Lewis superacid featuring exceptional structure and reactivity is disclosed. It enabled the formation of non‐classical electron deficient B−H−B type of bonding, which was supported by spectroscopic and structural parameters as well as computational studies. Taming the pyramidal Lewis acid electrophilicity through weak coordinating anion dissociation enabled a series of highly challenging chemical transformations, such as Csp2−H and Csp3−H activation under a frustrated Lewis pair regime and the cleavage of Csp3−Si bonds. The demonstration of such rich chemical behaviour and flexibility on a single molecular compound makes it a unique mediator of chemical transformations generally restricted to transition metals.
Copper‐Catalyzed 1,2‐Trifluoromethylation Carbonylation of Unactivated Alkenes: Efficient Access to β‐Trifluoromethylated Aliphatic Carboxylic Acid Derivatives
Authors: Wu Fu‐Peng , Yuan Yang , Wu Xiao‐Feng
Published: October 2021

A novel copper‐catalyzed carbonylative trifluoromethylation of unactivated alkenes has been developed. A broad range of β‐trifluoromethylated carboxylic acid derivatives were prepared in moderate to excellent yields from simple alkenes with excellent regioselectivity. It is noteworthy that ethylene gas, as the simplest olefin, can also be applied directly to obtain β‐trifluoromethylated amides and ester. This transformation presents the first example on carbonylative trifluoromethylation of alkenes.
Polysulfone membranes with the improved antibacterial property via surface co‐deposition of dopamine and sodium polystyrene sulfonate
Authors: Zhang Yan , Chen Bin , Zhao Haichao , Zhu Lijing
Published: October 2021

Mussel‐inspired dopamine (DA) surface modification has been widely recognized as a promoting strategy to design and exploit valuable multifunctional materials. Herein, polysulfone porous membrane was modified by the co‐deposition of DA and sodium polystyrene sulfonate. In the case of extended duration of the reaction time, the water contact angle of the membrane decreased by 30 ° and the color of the modified membrane presented dark. The rejection rates of bovine serum albumin and lysozyme can close to 100% of the modified membrane and the bacteriostatic rate reached 100% at 18 h. In addition, the co‐deposited membrane performed well bactericidal and excellent antiadhesion to Escherichia coli. This work provides a simple way for the fabrication of an antibacterial surface.
Study on electroactive shape memory behaviors of polyvinyl alcohol/waterborne polyurethane/short carbon fiber composites
Authors: Lin Liulan , Xu Yi , Sun Zhanli
Published: October 2021

The properties of electroactive shape memory composites fabricated from polyvinyl alcohol (PVA) and waterborne polyurethane (WPU) filled with short carbon fibers (SCFs) were studied. The addition of WPU effectively enhanced the elongation property and reduced the glass transition temperature. The elongation at break of the composites doubled, with a maximum content of WPU at nearly 50%. The tensile strength of the samples increased first and then decreased, reaching the maximum when the content of WPU was 10%. At the same time, the sample with WPU content of 10% showed the best electrical properties and the speed of response to external stimuli was faster. However, with the increase of WPU, the shape fixity ratio and the shape recovery ratio of the composites slightly dropped. Further, a reciprocating deformable robot was designed without adding any other materials, which could move forward under the action of alternating electric field. The above results indicated that the composites blended with an appropriate content of WPU could offer the possibility for the potential application in the field of soft robot.
Effect of varying polydimethylsiloxane chain length and content on the adhesion and thermal properties of polydimethylsiloxane‐grafted acrylic pressure‐sensitive adhesives
Authors: Park Hee‐Woong , Seo Hyun‐Su , Kwon Kiok , Shin Seunghan
Published: October 2021

Acrylic pressure‐sensitive adhesive (acrylic PSA) has advantages such as high adhesion, low cost, and high light transmittance, but it has a low adhesion to low‐surface‐energy substrates and low thermal stability. To solve these problems, PSA was modified with low surface energy moieties and crosslinked by UV curing. In this study, a polydimethylsiloxane (PDMS) structure with a low surface energy and good thermal properties was introduced into PSA through grafting polymerization to compensate for the disadvantages of acrylic PSA. PDMS‐grafted acrylic PSAs (PGPs) were synthesized by grafting through method using macromonomers with PDMS of three different lengths. They showed improved loop tack and 180° peel strength values on polypropylene, a low‐surface‐energy substrate. However, when a long PDMS‐based macromonomer (Mw ~ 5000) was used, phase separation was observed even at a low concentration, and the degree of improvement was decreased. The peel strength of PGPs significantly changed with dwelling time. As the surface energy difference between the substrate and PSA increased, the peel strength increased dramatically with dwelling time. 90° peel strengths measured with varying temperature (25–100°C) showed that a long PDMS chain was most effective in improving the thermal stability of the acrylic PSA by its own domains.
SMC/TPE bi‐layer configurations for structural vibration damping applications
Authors: Burgoa Aizeti , Lekube Blanca , Zulueta Kepa
Published: October 2021

Sheet molding compounds (SMCs) have considerable potential as lightweight alternative to traditional materials used in automotive components. However, despite their outstanding mechanical properties, their vibration damping characteristics are often relatively poor for several applications. Therefore, enhancing the vibration damping capability of SMCs represents a field with increasing interest. Application of viscoelastic layers to high stiffness materials, such as SMCs, represents an effective approach to add vibration damping functionalities to lightweight structural components. In this work, the incorporation of thermoplastic elastomers (TPEs) is studied as a novel strategy to enhance the structural vibration damping capability of SMCs. Several types of SMC and TPEs have been considered and the effect of TPE‐SMC thickness ratio on the damping and stiffness properties is investigated. The viscoelastic properties and vibration damping performance were evaluated by dynamic mechanical analysis. The effect of TPE addition on stiffness was studied by three‐point bending. Results reveal the potential of the incorporation of thin TPE layers as cost‐effective strategy to enlarge the vibration damping efficiency of SMCs while maintaining their overall high stiffness. It is expected that the bi‐material configurations presented in the current study will contribute to advance the development of new lightweight multi‐functional solutions for modern transport applications.
Modelling and predicting freshwater mussel distributions in the Midwestern USA
Authors: Schartel Tyler E. , Cao Yong , Henning Bridget , Feng Mei‐Ling , Hinz Leon C.
Published: October 2021

Historically diverse and abundant freshwater mussel communities in the Midwestern USA, as elsewhere in the world, are in substantial decline. An understanding of mussel distributions, habitat requirements and biodiversity is required to develop and optimize mussel conservation efforts.

Maxent was used to generate species distribution models (SDMs) based on a wide range of environmental variables. Binary predictions were generated using two approaches. Species richness (SR) was estimated through model stacking and evaluated with an independent dataset derived from intensive sampling. Two measures of species endemism were estimated. Factors important for mussel occurrence were identified and geospatial analyses characterized spatial patterns of predicted SR and endemism at multiple spatial scales.

SDMs generally performed at ‘fair’ or better levels (0.7 < AUC < 1). Stream size, climate and land use were important to mussel occurrence. SR estimates were positively and significantly correlated with observed SR in a separate dataset. SR and endemism hot and cold spots varied across spatial scales.

This study introduces a novel background selection process for aquatic SDMs that considers sampling biases, species records relative to stream size and species' geographical ranges. The results provide valuable insight into species status and distributions, important and actionable factors influencing mussel occurrence, and spatial patterns of highly diverse or endemic regions. This study demonstrates how synthesizing SDMs can inform regional, multi‐species efforts for conserving freshwater mussel diversity.
A creeping threat? Introduced Macquarie turtles and the future of endangered helmeted turtles in southern Australia
Authors: Chessman Bruce C.
Published: October 2021

The introduction of freshwater turtle species outside their natural ranges may threaten native turtles through competition for resources such as food or basking sites, hybridization, and transmission of diseases or parasites.

The three southern species of Australian helmeted turtles (Myuchelys bellii, Myuchelys georgesi, and Myuchelys purvisi) had no or minimal distributional overlap with the widespread Australian Macquarie turtle, Emydura macquarii, until about 30 years ago. Since that time, E. macquarii has been introduced within the ranges of all three Myuchelys spp., possibly through the release or escape of pet turtles.

The occurrence, catch per unit effort, and population structure of E. macquarii were compared among four introduced populations within the ranges of southern Myuchelys spp. and four native populations. The aim was to provide insight into the status of the introduced populations, their likely current impact on Myuchelys spp., and their potential for future increase.

Data analysis suggested that the introduced populations of E. macquarii are at varying stages of the invasion process and not yet severe threats to Myuchelys spp. However, continuing proliferation of introduced E. macquarii is likely, potentially placing intensifying pressure on Myuchelys populations in the long term.

Research is needed on interactions of E. macquarii and Myuchelys spp. and their comparative competitive abilities in order to inform the difficult policy decision of whether invasive E. macquarii should be removed or controlled.
Sexual size and shape dimorphism in Turkish common toads (Bufo bufoLinnaeus 1758)
Authors: Dursun Cantekin , Gül Serkan , Özdemir Nurhayat
Published: October 2021

Differences in male and female traits (sexual dimorphism [SD]) are widespread in animals. Dimorphism in morphological characters evolves under the effect of environmental and genetic factors and is shaped by natural and sexual selection. In this study, intersexual differences in size and shape in common toad,Bufo bufo, populations in Turkey were investigated. For this, linear measurements of 27 body‐related morphometric characters in a sample of 140 individuals (70 males and 70 females) were compiled. The data were analyzed using univariate and multivariate statistical methods. The results show SD in body size with females having larger body size, a trait related with fecundity and thus probably under sexual selection. Body shape differences, which are associated with head width and dorsal head, are likely to prey size. Male‐biased differences observed in nasal characters and tympanum may also be associated with sexual selection (male–male competition). Our findings are consistent with previous studies of major of Anura and support a role for selection pressures acting differentially upon individuals from both sexes, resulting in the evolution of sexually dimorphic traits.
Impact of Imine Bond Orientations on the Geometric and Electronic Structures of Imine‐based Covalent Organic Frameworks
Authors: Xun Sangni , Li Hong , Sini Gjergji , Bredas Jean‐Luc
Published: October 2021

Many efforts are currently devoted to improving the stability and crystallinity of imine‐based two‐dimensional (2D) covalent organic frameworks (COFs) given their wide range of potential applications. The variation in the relative orientations of the imine bonds has been found to be a critical factor that impacts the stacking of the 2D COF layers, leads to the formation of isomer structures, and influences the crystallinity of the final product. Most investigations to date have focused only on the structural properties, while the role of the imine orientations on the electronic properties has not been studied systematically. Here, we explore this effect by examining how the electronic band structures, electronic couplings, and effective masses evolve when considering four isomeric structures of an imine‐linked tetraphenyl‐pyrene naphthalene‐diimide COF. Our results provide an understanding of the impact of the imine orientations and how they need to be controlled to realize COF inter‐layer stackings that can lead to efficient cross‐plane electron transport. They can be used to guide the design and synthesis of imine‐based COFs for applications where charge transport needs to be optimized.
Crystal Structure Transformation in Hydrogen‐bonded Organic Frameworks via Ion Exchange
Authors: Liu Ying , Dai Juanjuan , Zhang Zhiguo , Yang Yiwen , Yang Qiwei , Ren Qilong , Bao Zongbi
Published: October 2021

Hydrogen‐bonded organic frameworks (HOFs) have emerged as rapidly growing porous materials while established permanent porosities are very fragile and difficult to stabilize due to weak hydrogen‐bonding interactions among building units. Herein, we report a stable hydrogen‐bonded metallotecton framework (termed as HOF‐ZJU‐102) that was constructed through hydrogen‐bonding networks between cationic metal‐organic complexes [Cu2(Hade)4(H2O)2]4+ (Hade=adenine) and GeF62− anions. The framework not only shows permanent porosity, but also exhibits efficient separation performance of C2H2/C2H4 at room temperature. More interestingly, its crystal structure could be irreversibly transformed into isostructural counterpart HOF‐ZJU‐101 by ion exchange in the SiF62− containing solution, evidenced by multiple characterization techniques including gas sorption measurements, 19F NMR spectra, FTIR and EDS. Utilizing such an ion exchange mechanism, the collapsed HOF‐ZJU‐102 could be restored into HOF‐ZJU‐101 by simply soaking in the salt solution.
Statistical disclosure control for continuous variables using an extended skew‐t copula
Authors: Chu Amanda M. Y. , Ip Chun Yin , Lam Benson S. Y. , So Mike K. P.
Published: October 2021

In this article, we extend the skew‐t data perturbation (STDP) to develop a new statistical disclosure control (SDC) method for data with continuous variables. In this new SDC method, we construct an extended skew‐t (EST) copula to release confidential data for third‐party usage. Using the EST copula for producing perturbed data, we can incorporate rich statistical information in the perturbed data while preserving the marginal distributions of the data. An advancement of this EST‐SDC method is to use a copula distribution, which allows generation of perturbed data from bivariate conditional EST copulas sequentially. We discuss the methodology of EST‐SDC and outline some statistical properties derived from copula theories. Simulations and a real data study are included to demonstrate how the EST‐SDC method can be applied and to compare with the STDP method.