bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonvolatile Electrical Control and Heterointerface‐Induced Half‐Metallicity of 2D Ferromagnets
Authors: Zhao Yinghe , Zhang Jun‐Jie , Yuan Shijun , Chen Zhongfang
Published: April 2019

Electrical control of atom‐thick van der Waals (vdW) ferromagnets is a key toward future magnetoelectric nanodevices; however, state‐of‐the‐art control approaches are volatile. In this work, introducing ferroelectric switching as an aided layer is demonstrated to be an effective approach toward achieving nonvolatile electrical control of 2D ferromagnets. For example, when a ferromagnetic monolayer CrI3 and ferroelectric MXene Sc2CO2 come together into multiferroic heterostructures, CrI3 is controlled by polarized states P↑ and P↓ of Sc2CO2. P↑ Sc2CO2 does not change the semiconducting nature of CrI3, but surprisingly P↓ Sc2CO2 makes CrI3 half‐metallic. Nonvolatility of the electrical switching between two oppositely ferroelectric polarized states, therefore, indirectly enables nonvolatile electrical control of CrI3 between ferromagnetic semiconductor and half‐metal. The heterointerface‐induced half‐metallicity in CrI3 is intrinsic without resorting to any chemical functionalization or external physical modification, which is rather beneficial to the practical application. This work paves the way for nonvolatile electrical control of 2D vdW ferromagnets and applications of CrI3 in half‐metal‐based nanospintronics.
Highly Stretchable Polymers: Mechanical Properties Improvement by Balancing Intra‐ and Intermolecular Interactions
Authors: Galant Or , Bae Suwon , Silberstein Meredith N. , Diesendruck Charles E.
Published: April 2019

The mechanical properties of polymers are highly dependent on the mobility of the underlying chains. Changes in polymer architecture can affect inter‐ and intramolecular interactions, resulting in different chain dynamics. Herein, an enhancement in the mechanical properties of poly(butylmethacrylate) is induced by folding the polymer chains through covalent intramolecular crosslinking (CL). Intramolecular CL causes an increase in intramolecular interactions and inhibition of intermolecular interactions. In both the glassy and rubbery states, this molecular rearrangement increases material stiffness. In the glassy state, this molecular rearrangement also leads to reduced failure strain, but surprisingly, in the rubbery state, the large strain elasticity is actually increased. An intermediate intramolecular CL degree, where there is a balance between intra‐ and intermolecular interactions, shows optimal mechanical properties. Molecular dynamics simulations are used to confirm and provide molecular mechanisms to explain the experimental results.
Effects of Programmed Local Delivery from a Micro/Nano‐Hierarchical Surface on Titanium Implant on Infection Clearance and Osteogenic Induction in an Infected Bone Defect
Authors: Li Dize , Li Yihan , Shrestha Annie , Wang Si , Wu Qingqing , Li Lingjie , Guan Chao , Wang Chao , Fu Tiwei , Liu Wenzhao , Huang Yuanding , Ji Ping , Chen Tao
Published: April 2019

The two major causes for implant failure are postoperative infection and poor osteogenesis. Initial period of osteointegration is regulated by immunocytes and osteogenic‐related cells resulting in inflammatory response and tissue healing. The healing phase can be influenced by various environmental factors and biological cascade effect. To synthetically orchestrate bone‐promoting factors on biomaterial surface, built is a dual delivery system coated on a titanium surface (abbreviated as AH‐Sr‐AgNPs). The results show that this programmed delivery system can release Ag+ and Sr2+ in a temporal‐spatial manner to clear pathogens and activate preosteoblast differentiation partially through manipulating the polarization of macrophages. Both in vitro and in vivo assays show that AH‐Sr‐AgNPs‐modified surface renders a microenvironment adverse for bacterial survival and favorable for macrophage polarization (M2), which further promotes the differentiation of preosteoblasts. Infected New Zealand rabbit femoral metaphysis defect model is used to confirm the osteogenic property of AH‐Sr‐AgNPs implants through micro‐CT, histological, and histomorphometric analyses. These findings demonstrate that the programmed surface with dual delivery of Sr2+ and Ag+ has the potential of achieving an enhanced osteogenic outcome through favorable immunoregulation.
Beyond 1000 nm Emission Wavelength: Recent Advances in Organic and Inorganic Emitters for Deep‐Tissue Molecular Imaging
Authors: Ding Feng , Fan Yong , Sun Yao , Zhang Fan
Published: April 2019

In vivo second near‐infrared (NIR‐II, 1.0–1.7 µm) bioimaging , a rapidly expanding imaging tool for preclinical diagnosis and prognosis, is of great importance to afford precise dynamic actions in vivo with high spatiotemporal resolution, deeper penetration, and decreasing light absorption and scattering. In the course of preclinical practices, organic and inorganic emitters with NIR‐II signals are indispensable keys to open the invisible biological window. In this review, NIR‐II emitters, including but not limited to organic emitters like organic small molecules and copolymers, and inorganic emitters such as lanthanide‐based nanocrystals, quantum dots like Ag2S dots, and carbon nanotubes, are described, especially regarding their unique optical features and noteworthy functions for animal bioimaging. Along with these existing advances, the challenges and potential spaces for further progress are discussed to offer an approximate direction for future researches.
Homogeneous Anodic TiO2 Nanotube Layers on Ti–6Al–4V Alloy with Improved Adhesion Strength and Corrosion Resistance
Authors: Hu Nan , Hu Tao , Gao Ang , Gao Nong , Starink Marco J. , Chen Ying , Sun Wanting , Liao Qing , Tong Liping , Xu Xiaochang , Chu Paul K. , Wang Huaiyu
Published: April 2019

Hexagonal TiO2 nanotubes (TNTs) arrays are generally fabricated on Ti‐based substrates for some biomedical purposes, but the TNT layers constructed on conventionally processed Ti alloys are usually inhomogeneous because the substrates typically contain both the α and β phases. In this work, high‐pressure torsion (HPT) is applied to obtain a saturated single α‐phase microstructure in Ti–6Al–4V alloys via strain‐induced β phase dissolution. Homogeneous anodic TNT layers with three different morphologies, one‐step nanoporous, one‐step nanotubular, and two‐step nanoporous structures, are electrochemically fabricated on the ultrafine‐grained (UFG) Ti–6Al–4V alloy substrates after HPT processing, whereas the TNT layers prepared on coarse‐grained substrates are normally inhomogeneous. More notably, the TNT layers show significantly improved adhesion strength to the UFG substrate as well as better corrosion resistance compared to those on the conventionally processed Ti–6Al–4V substrates. X‐ray diffraction analysis, scanning electron microscopy in combination with electron backscatter diffraction, and transmission electron microscopy indicate that the improvement is due to a larger dislocation density in the UFG substrate as well as strain‐induced β phase dissolution.
An Eco‐Friendly, CMOS‐Compatible Transfer Process for Large‐Scale CVD‐Graphene
Authors: Moon Ji‐Yun , Kim Seung‐Il , Son Seok‐Kyun , Kang Seog‐Gyun , Lim Jae‐Young , Lee Dong Kyu , Ahn Byungmin , Whang Dongmok , Yu Hak Ki , Lee Jae‐Hyun
Published: April 2019

Since the first realization of graphene synthesis through the chemical vapor deposition (CVD) method in 2009, CVD‐graphene is regarded as a key material in the future electronics industry, and one that requires high standard characteristics. However, because graphene itself is not a semiconductor, therefore it does not have a bandgap, a promising application is considered to integrate its use with semiconductors, rather than completely replace Si or Ge. Although numerous methods for a clean and uniform graphene transfer process are developed, graphene growth and transfer methods that are applicable to current mainstream Si‐based complementary metal‐oxide‐semiconductor (CMOS) manufacturing processes are not yet introduced. This study implements an eco‐friendly and CMOS‐compatible graphene transfer process through water‐soluble inorganic MoO3 film as a supporting layer. Since the monolayer graphene is grown on hydrogen‐terminated semiconductor Ge surface, the MoO3 thin film coated graphene is easily delaminated from the Ge substrate. The separated graphene could be transferred to arbitrary substrate without a chemical wet etching process, and the remaining Ge substrate could be employed for about 50 times multiple reuse for the growth of graphene, without degradation of the crystallinity of the graphene.
Thermally Dependent Dynamic Meta‐Holography Using a Vanadium Dioxide Integrated Metasurface
Authors: Liu Xingbo , Wang Qiu , Zhang Xueqian , Li Hua , Xu Quan , Xu Yuehong , Chen Xieyu , Li Shaoxian , Liu Meng , Tian Zhen , Zhang Caihong , Zou Chongwen , Han Jiaguang , Zhang Weili
Published: April 2019

Metasurfaces have drawn enormous attention in both the physics and engineering communities owing to their capabilities of arbitrarily manipulating the electromagnetic waves at subwavelength scale. One of the promising applications of metasurfaces is the realization of high‐quality holograms. However, due to the passive response of metasurface resonators, previous demonstrations on meta‐holography were mainly limited to generating static images. Seeking new approaches to realize active control over meta‐holograms is highly demanded for display applications, such as holographic movies. Here, a broadband active meta‐holography which enables temperature‐dependent dynamic holographic imaging is experimentally demonstrated. The meta‐hologram consists of two sets of resonators: set 1 is passive, being composed of simple metallic C‐shape split‐ring resonators (CSRRs) and set 2 is active, being composed of vanadium dioxide (VO2) integrated CSRRs (V‐CSRRs). Each set generates certain holographic images with predesigned amplitude and phase distributions. Under external heating, the insulator‐to‐metal transition property of VO2 will gradually short out the V‐CSRRs and their responses, thus dynamically changing the overall generated holographic image. The proposed approach presents a new way of tunable metasurface design and holds promise for active meta‐devices with versatile functionalities.
Bright and Multicolor Chemiluminescent Carbon Nanodots for Advanced Information Encryption
Authors: Shen Cheng‐Long , Lou Qing , Lv Chao‐Fan , Zang Jin‐Hao , Qu Song‐Nan , Dong Lin , Shan Chong‐Xin
Published: April 2019

The various luminescent properties of carbon nanodots (CDs) reveal fascinating applications in several areas. Here, bright and multicolor chemiluminescence (CL) is realized from CDs, whose CL quantum yield can be optimized by adjusting the energy level alignment between the CDs and 1,2‐dioxetanedione intermediate generated from the reaction of peroxalate and hydrogen peroxide. A CL quantum yield of 9.32 × 10−3 Einsteins mol−1, maximal luminance of 3.28 cd m−2, and lifetime of 186.4 s are achieved in red CDs, all of which are the best values ever reported for CDs. As a proof‐of‐concept prototype, a high‐quality information encryption strategy is established via CD based CL imaging techniques by virtue of the high brightness and multicolor CL.
Iron–Salen Complex and Co2+ Ion‐Derived Cobalt–Iron Hydroxide/Carbon Nanohybrid as an Efficient Oxygen Evolution Electrocatalyst
Authors: Du Jian , Liu Guoquan , Li Fei , Zhu Yong , Sun Licheng
Published: April 2019

Metal–salen complexes are widely used as catalysts in numerous fundamental organic transformation reactions. Here, CoFe hydroxide/carbon nanohybrid is reported as an efficient oxygen evolution electrocatalyst derived from the in situ formed molecular Fe–salen complexes and Co2+ ions at a low temperature of 160 °C. It has been evidenced that Fe–salen as a molecular precursor facilitates the confined‐growth of metal hydroxides, while Co2+ plays a critical role in catalyzing the transformation of organic ligand into nanocarbons and constitutes an essential component for CoFe hydroxide. The resulting Co1.2Fe/C hybrid material requires an overpotential of 260 mV at a current density of 10 mA cm−2 with high durability. The high activity is contributed to uniform distribution of CoFe hydroxides on carbon layer and excellent electron conductivity caused by intimate contact between metal and nanocarbon. Given the diversity of molecular precursors, these results represent a promising approach to high‐performance carbon‐based water splitting catalysts.
3D Printing of Personalized Thick and Perfusable Cardiac Patches and Hearts
Authors: Noor Nadav , Shapira Assaf , Edri Reuven , Gal Idan , Wertheim Lior , Dvir Tal
Published: April 2019

Generation of thick vascularized tissues that fully match the patient still remains an unmet challenge in cardiac tissue engineering. Here, a simple approach to 3D‐print thick, vascularized, and perfusable cardiac patches that completely match the immunological, cellular, biochemical, and anatomical properties of the patient is reported. To this end, a biopsy of an omental tissue is taken from patients. While the cells are reprogrammed to become pluripotent stem cells, and differentiated to cardiomyocytes and endothelial cells, the extracellular matrix is processed into a personalized hydrogel. Following, the two cell types are separately combined with hydrogels to form bioinks for the parenchymal cardiac tissue and blood vessels. The ability to print functional vascularized patches according to the patient's anatomy is demonstrated. Blood vessel architecture is further improved by mathematical modeling of oxygen transfer. The structure and function of the patches are studied in vitro, and cardiac cell morphology is assessed after transplantation, revealing elongated cardiomyocytes with massive actinin striation. Finally, as a proof of concept, cellularized human hearts with a natural architecture are printed. These results demonstrate the potential of the approach for engineering personalized tissues and organs, or for drug screening in an appropriate anatomical structure and patient‐specific biochemical microenvironment.
Defect Self‐Compensation for High‐Mobility Bilayer InGaZnO/In2O3 Thin‐Film Transistor
Authors: He Jiawei , Li Guoli , Lv Yawei , Wang Chunlan , Liu Chuansheng , Li Jinchai , Flandre Denis , Chen Huipeng , Guo Tailiang , Liao Lei
Published: April 2019

Here, the bilayer InGaZnO/In2O3 thin‐film transistors (TFTs) are deposited by radio‐frequency magnetron sputtering at room temperature. A high field‐effect mobility (μFE) of 64.4 cm2 V−1 s−1 and a small subthreshold swing (SS) of 204 mV per decade are achieved in the bilayer‐stack TFTs fabricated upon SiO2/Si substrate, with large improvement compared to the single‐layer InGaZnO and In2O3 TFTs. Implementing HfO2 and Si3N4 as high‐k gate dielectrics, μFE and SS are correspondingly enhanced to be 67.5 and 79.1 cm2 V−1 s−1, and 85 and 92 mV per decade in the bilayer TFTs. Defect self‐compensation effect is also revealed, i.e., (In)+ + (O)− → In − O, while, respectively, considering the indium‐ and oxygen‐related defects in InGaZnO and In2O3 and exploring the numerical simulations in SILVACO/Atlas (for electrical performance) and Quantum Espresso (for physical analysis). The InO formation can result in a significant reduction in defect density (validated by the X‐ray photoelectron spectra and low‐frequency noise characterizations) and therefore improvement of μFE and SS in the bilayer‐stack TFT. The important role of defect self‐compensation mechanism while combining different individual channel layers in the oxide semiconducting TFTs is underlined and highly potential application in next‐generation, fast‐speed flexible displays is shown.
Conductive Metal–Organic Frameworks Selectively Grown on Laser‐Scribed Graphene for Electrochemical Microsupercapacitors
Authors: Wu Hao , Zhang Wenli , Kandambeth Sharath , Shekhah Osama , Eddaoudi Mohamed , Alshareef Husam N.
Published: April 2019

Conductive 2D metal–organic frameworks (MOFs) have merits beyond traditional MOFs for electrochemical applications, but reports on using MOFs as electrodes for electrochemical microsupercapacitors (MSCs) are practically non‐existent. In this work, a Ni‐catecholate‐based MOF (Ni‐CAT MOF) having good conductivity and exhibiting redox chemistry in the positive and negative voltage windows is developed. A novel process is developed to selectively grow the conductive Ni‐CAT MOF on 3D laser scribed graphene (LSG). The LSG with its superior wettability serves as a functional matrix‐current collector for the hybridization of conductive Ni‐CAT MOF nanocrystals. Impressively, MSCs fabricated using the hybrid LSG/Ni‐CAT MOF show significant improvement compared with MOF‐free LSG electrodes. Specifically, the LSG/Ni‐CAT MOF electrodes can deliver MSCs with a wide operating voltage (1.4 V), high areal capacitance (15.2 mF cm−2), energy density (4.1 µWh cm−2), power density (7 mW cm−2), good rate performance, and decent cycling stability. This work opens up an avenue for developing electrochemical microsupercapacitors using conductive MOF electrodes.
Divergence in floral trait preferences between nonflower‐specialized birds and insects on the Galápagos
Authors: Hervías‐Parejo Sandra , Heleno Ruben , Nogales Manuel , Olesen Jens M. , Traveset Anna
Published: April 2019

Premise of the Study

The characteristic scarcity of insects on remote oceanic islands has driven nonflower‐specialized vertebrates to broaden their trophic niches and explore floral resources. From our previous studies in the Galápagos, we know that native insectivorous and frugivorous birds visit a wide range of entomophilous flowers and can also act as effective pollinators. Here, we tested whether opportunistic Galápagos birds show any preference for specific floral traits, and if so, this preference differs from that of insects.

Methods

Sixteen floral morphology and nectar traits of 26 native species were studied, as well as the frequency with which they are visited by birds and insects. Nonmetric multidimensional scaling (NMDS) was used to evaluate the distribution of flower traits values along two main dimensions and measure the similarity between the plants visited mostly by birds versus those by insects.

Key Results

NMDS of floral traits resulted in two species groups: (1) bell‐shaped, white flowers with wider corollas at nectary level and higher nectar volume, associated with high bird visitation rates; and (2) bowl and tubular‐shaped flowers with narrower corollas at nectary level and lower nectar volume, associated with high insect visitation rates.

Conclusions

Despite the divergence in floral trait preferences between opportunistic Galápagos birds and insects, bird‐visited flowers display mixed traits not fitting the classical ornithophilous syndrome. This finding is compatible with the existence of a transitional or bet‐hedging phenotype between insect and bird visitors and underscores the importance of coevolution and floral diversification in nonspecialized plant–visitor interactions.
Developing Through‐Space Charge Transfer Polymers as a General Approach to Realize Full‐Color and White Emission with Thermally Activated Delayed Fluorescence
Authors: Hu Jun , Li Qiang , Wang Xingdong , Shao Shiyang , Wang Lixiang , Jing Xiabin , Wang Fosong
Published: April 2019

Through‐space charge transfer polymers (TSCT polymers) that contain a non‐conjugated polystyrene backbone and spatially separated donor and acceptor units for solution‐processed OLEDs with full‐color and white emission is reported. By tuning the charge transfer strength between donor and acceptors with different electron‐accepting ability, emission color spanning from deep blue to red can be achieved. By incorporating two kinds of donor/acceptor pairs in one polymer to create duplex through‐space charge‐transfer channels, blue and yellow emission can be simultaneously obtained to realize white electroluminescence from a single polymer. The TSCT polymers exhibit thermally activated delayed fluorescence effect with delayed‐component lifetimes in range of 0.36–1.98 μs, and unexpected aggregation‐induced emission (emission intensity enhancement of up to 117 from solution to aggregation state).
Access to a Key Building Block for the Prostaglandin Family via Stereocontrolled Organocatalytic Baeyer–Villiger Oxidation
Authors: Zhu Kejie , Hu Sha , Liu Minjie , Peng Haihui , Chen Fen‐Er
Published: April 2019

A new protocol for the construction of a crucial bicyclic lactone of prostaglandins using a stereocontrolled organocatalytic Baeyer–Villiger (B‐V) oxidation was developed. The key B‐V oxidation of a racemic cyclobutanone derivative with aqueous hydrogen peroxide has enabled an early‐stage construction of a bicyclic lactone skeleton in high enantiomeric excess (up to 95 %). The generated bicyclic lactone is fully primed with two desired stereocenters and enabled the synthesis of the entire family of prostaglandins according to Corey′s route. Furthermore, the reactivity and enantioselectivity of B‐V oxidation of racemic bicyclic cyclobutanones were evaluated and 90–99 % ee was obtained, representing one of the most efficient routes to chiral lactones. This study further facilitates the synthesis of prostaglandins and chiral lactone‐containing natural products to promote drug discovery.
Mechanochromism, Twisted/Folded Structure Determination, and Derivatization of (N‐Phenylfluorenylidene)acridane
Authors: Matsuo Yutaka , Wang Ya , Ueno Hiroshi , Nakagawa Takafumi , Okada Hiroshi
Published: April 2019

(N‐Phenylfluorenylidene)acridane (Ph‐FA) compounds with electron‐withdrawing and ‐donating substituents (H, MeO, Ph, NO2, Br, F) at the para position of the phenyl group were successfully synthesized by Barton–Kellogg reactions of N‐aryl thioacridones and diazofluorene. By using the substituent on the nitrogen atom to alter the electronic properties, both the folded and twisted conformers of p‐NO2‐C6H4‐FA could be crystallographically characterized, which enabled the charge transfer from the electron‐donating acridane moiety to the electron‐accepting fluorenylidene moiety to be understood. Ground‐state mechanochromism, thermochromism, vapochromism, and proton‐induced chromism were demonstrated between the folded and twisted conformations of the conformers. Protonation and chemical oxidation of Ph‐FA gave two stable acridinium compounds, namely, the fluorenylacridinium and acridinium radical cations. The present study will contribute to the development of functional dyes and organic semiconductors.
Heterodiatomare Mehrfachbindung zwischen Elementen der Gruppe 13: Ein Komplex mit B‐Al‐π‐Bindung reduziert CO2
Authors: Hofmann Alexander , Légaré Marc‐André , Wüst Leonie , Braunschweig Holger
Published: April 2019

Verbindungen mit heterodiatomarer Mehrfachbindung zwischen Gruppe‐13‐Elementen sind bislang unbekannt. In dieser Zuschrift berichten wir über eine Darstellungsmethode von [(CAAC)PhB=AlCp3t] (1), einem Komplex, bei dem zwei Singulettfragmente nach Assoziation eine π‐Bindung zwischen Bor und Aluminium bilden. Neben den Eigenschaften dieser Mehrfachbindung wird die Reaktivität von 1 gegenüber CO2 präsentiert. Diese führt über eine ungewöhnliche Metathesereaktion zu einer B‐CO‐Verbindung.
Sr6Cd2Sb6O7S10: Strong SHG Response Activated by Highly Polarizable Sb/O/S Groups
Authors: Wang Ruiqi , Liang Fei , Wang Fakun , Guo Yangwu , Zhang Xian , Xiao Yi , Bu Kejun , Lin Zheshuai , Yao Jiyong , Zhai Tianyou , Huang Fuqiang
Published: April 2019

A new nonlinear optical (NLO) oxysulfide, Sr6Cd2Sb6O7S10, which contains the functional groups [SbOxS5−x]7− (x=0, 1) with a 5s2 electron configuration, is synthesized by a solid‐state reaction. This compound displays a phase‐matchable second harmonic generation (SHG) response four times stronger than AgGaS2 (AGS) under laser irradiation at 2.09 μm. Single‐crystal‐based optical measurements reveal a SHG intensity that can be tuned by temperature and novel photoluminescence properties. Theoretical analyses demonstrate that tetragonal [SbOS4]7− and [SbS5]7− pyramids make the predominant contribution to the enhanced SHG effect. Among those, the [SbOS4]7− units with mixed anions make a larger contribution. This work proposes that oxysulfide groups with an ns2 electron configuration can serve as new functional building units in NLO materials and opens a new avenue for the design of other optoelectronic materials.
Cobalt‐Catalyzed Enantioselective Hydroboration/Cyclization of 1,7‐Enynes: Asymmetric Synthesis of Chiral Quinolinones Containing Quaternary Stereogenic Centers
Authors: Wu Caizhi , Liao Jiayu , Ge Shaozhong
Published: April 2019

An asymmetric cobalt‐catalyzed hydroboration/cyclization of 1,7‐enynes to synthesize chiral six‐membered N‐heterocyclic compounds was developed. A variety of aniline‐tethered 1,7‐enynes react with pinacolborane to afford the corresponding chiral boryl‐functionalized quinoline derivatives in high yields with high enantioselectivity. This cobalt‐catalyzed asymmetric cyclization of 1,7‐enyens provides a general approach to access a series of chiral quinoline derivatives containing quaternary stereocenters.
A Gas‐Phase CanMn4−nO4+ Cluster Model for the Oxygen‐Evolving Complex of Photosystem II
Authors: Mauthe Silvia , Fleischer Irene , Bernhardt Thorsten M. , Lang Sandra M. , Barnett Robert N. , Landman Uzi
Published: April 2019

One of the fundamental processes in nature, the oxidation of water, is catalyzed by a small CaMn3O4⋅MnO cluster located in photosystem II (PS II). Now, the first successful preparation of a series of isolated ligand‐free tetrameric CanMn4−nO4+ (n=0–4) cluster ions is reported, which are employed as structural models for the catalytically active site of PS II. Gas‐phase reactivity experiments with D2O and H218O in an ion trap reveal the facile deprotonation of multiple water molecules via hydroxylation of the cluster oxo bridges for all investigated clusters. However, only the mono‐calcium cluster CaMn3O4+ is observed to oxidize water via elimination of hydrogen peroxide. First‐principles density functional theory (DFT) calculations elucidate mechanistic details of the deprotonation and oxidation reactions mediated by CaMn3O4+ as well as the role of calcium.
Selenium‐Modified Microgels as Bio‐Inspired Oxidation Catalysts
Authors: Tan Kok H. , Xu Wenjing , Stefka Simon , Demco Dan E. , Kharandiuk Tetiana , Ivasiv Volodymyr , Nebesnyi Roman , Petrovskii Vladislav S. , Potemkin Igor I. , Pich Andrij
Published: April 2019

Active colloidal catalysts inspired by glutathione peroxidase (GPx) were synthesized by integration of catalytically active selenium (Se) moieties into aqueous microgels. A diselenide crosslinker (Se X‐linker) was successfully synthesized and incorporated into microgels through precipitation polymerization, along with the conventional crosslinker N,N′‐methylenebis(acrylamide) (BIS). Diselenide bonds within the microgels were cleaved through oxidation by H2O2 and converted to seleninic acid whilst maintaining the intact microgel microstructure. Through this approach catalytically active microgels with variable amounts of seleninic acid were synthesized. Remarkably, the microgels exhibited higher catalytic activity and selectivity at low reaction temperatures than the molecular Se catalyst in a model oxidation reaction of acrolein to acrylic acid and methyl acrylate.
The Rise of Fiber Electronics
Authors: Xu Xiaojie , Xie Songlin , Zhang Ye , Peng Huisheng
Published: April 2019

As a new direction in applied chemistry, fiber electronics allow device configuration to evolve from three to two dimensions and then to one dimension. The reduction in dimension brings unique properties, such as ultraflexibility, tissue adaptability, and weavability, enabling their use in a variety of applications, particularly in various emerging fields related to implantable devices and wearable systems. The different types of fiber electrode materials are summarized based on the one‐dimensional configuration and their distinctive interfaces, various devices, and promising applications. The remaining challenges and future directions are finally highlighted.
Biomimetic Chiral Photonic Crystals
Authors: Lv Jiawei , Ding Defang , Yang Xuekang , Hou Ke , Miao Xiang , Wang Dawei , Kou Baichuan , Huang Ling , Tang Zhiyong
Published: April 2019

Although it is well known that the amazing iridescent colors of the cuticle of beetles reflect the intricate nanoscale organization of bio‐fibers, artificial inorganic materials with comparable optical responses have not yet been synthesized from abiotic nanoscale building blocks. Such materials could find broad applications, including in circular polarizers, to generate circularly polarized luminescence, or in lasers. Herein, we describe a general method for the fabrication of biomimetic chiral photonic crystals by Langmuir–Schaefer assembly of colloidal inorganic nanowires. We not only reproduced the intricate helical structure and circularly polarized color reflection observed in beetles, but also achieved the highest chiroptical activity with a dissymmetry factor of −1.6 ever reported for chiral inorganic nanostructures. More importantly, the programmable structural control based on the precise interlayer arrangement endows us with unprecedented freedom to manipulate the optical activity of as‐fabricated chiral photonic crystals.
Spectroscopic, textural, electrical and magnetic properties of antimicrobial nano Fe(III) Schiff base complex
Authors: Mousa Emad S. , Mahmoud Walaa H.
Published: April 2019

A novel Schiff base ligand (L) was prepared through condensation of 2,6‐diaminopyridine and dibenzoyl methane in a 1:1 ratio. This Schiff base ligand was used for complex formation reaction with Fe(III) chloride. The structures of the ligand and its complex were deduced from elemental analyses, mass spectroscopy, 1H NMR, IR, UV‐Vis, electronic spectra, magnetic moment, molar conductivity measurements, thermogravimetric analyses and X‐ray diffraction. The molecular and electronic structures of both ligand and complex were optimized theoretically using density function theory (DFT) method. Moreover, the antimicrobial activities of the prepared compounds were studied and proven against some pathogenic bacteria. The Fe(III) complex had higher biological activity than that of the free ligand. Proceeding from the collected information, the properties of the complex were further investigated. The particle size was determined by dynamic light scattering technique to be 92.59 nm. Textural properties of the nano complex were studied by N2 adsorption to estimate the specific surface area, pore volume and pore size distribution. The pores in the complex were found in the micropore–mesopore range. Differential scanning calorimetric measurements reveal the existence of four endothermic peaks at 243.8, 308, 339.8 and 380.5 K. Dielectric properties and conductivity were scanned at different frequencies and temperatures. The dielectric constant reaches a peak value of 600 at ~390 K, 30 Hz. A cross‐over from the universal dielectric response to the super linear power law of conductivity was reported for this complex at T ≤ 345 K. Finally, the AC‐magnetic susceptibility measurements were carried out in the low‐temperature region. The complex showed paramagnetic behavior with a slight change in the magnitude of its magnetic moment at T = 244 K.
A transformation‐based approach to Gaussian mixture density estimation for bounded data
Authors: Scrucca Luca
Published: April 2019

Finite mixture of Gaussian distributions provide a flexible semiparametric methodology for density estimation when the continuous variables under investigation have no boundaries. However, in practical applications, variables may be partially bounded (e.g., taking nonnegative values) or completely bounded (e.g., taking values in the unit interval). In this case, the standard Gaussian finite mixture model assigns nonzero densities to any possible values, even to those outside the ranges where the variables are defined, hence resulting in potentially severe bias. In this paper, we propose a transformation‐based approach for Gaussian mixture modeling in case of bounded variables. The basic idea is to carry out density estimation not on the original data but on appropriately transformed data. Then, the density for the original data can be obtained by a change of variables. Both the transformation parameters and the parameters of the Gaussian mixture are jointly estimated by the expectation‐maximization (EM) algorithm. The methodology for partially and completely bounded data is illustrated using both simulated data and real data applications.
Whole‐bacterium ribosome display selection for isolation of highly specific anti‐Staphyloccocus aureus Affitins for detection‐ and capture‐based biomedical applications
Authors: Béhar Ghislaine , Renodon‐Cornière Axelle , Kambarev Stanimir , Vukojicic Petar , Caroff Nathalie , Corvec Stéphane , Mouratou Barbara , Pecorari Frédéric
Published: April 2019

Detection and capture methods using antibodies have been developed to ensure identification of pathogens in biological samples. Though antibodies have many attractive properties, they also have limitations and there are needs to expand the panel of available affinity proteins with different properties. Affitins, that we developed from the Sul7d proteins, are a solid class of affinity proteins, which can be used as substitutes to antibodies or to complement them. We report the generation and characterization of antibacterial Affitins with high specificity for Staphylococcus aureus. For the first time, ribosome display selections were carried out using whole‐living‐cell and naïve combinatorial libraries, which avoid production of protein targets and immunization of animals. We showed that Affitin C5 exclusively recognizes S. aureus among dozens of strains, including clinical ones. C5 binds staphylococcal Protein A (SpA) with a K
D of 108 ± 2 nM and has a high thermostability (T
m = 77.0°C). Anti‐S. aureus C5 binds SpA or bacteria in various detection and capture applications, including ELISA, western blot analysis, bead‐fishing, and fluorescence imaging. Thus, novel anti‐bacteria Affitins which are cost‐effective, stable, and small can be rapidly and fully designed in vitro with high affinity and specificity for a surface‐exposed marker. This class of reagents can be useful in diagnostic and biomedical applications.
New insights into the performance characteristics of the Planova‐series hollow‐fiber parvovirus filters using confocal and electron microscopy
Authors: Nazem‐Bokaee Hadi , Chen Dayue , O'Donnell Sean Michael , Zydney Andrew L.
Published: April 2019

Virus filtration remains a critical step in the downstream process for the production of monoclonal antibodies and other mammalian cell‐derived biotherapeutics. Recent studies have shown large differences in virus capture behavior of different virus filters, although the origin of these differences is still unclear. The objective of this study was to use confocal and scanning electron microscopy to directly evaluate the capture of virus‐size nanoparticles in Planova 20N and BioEX hollow‐fiber virus filters. Confocal images of fluorescent nanoparticles were quantified using ImageJ image processing software based on the measured fluorescence intensity of the labeled nanoparticles. Nanoparticle capture by the Planova BioEX was independent of transmembrane pressure from 10 to 45 psi. In contrast, the Planova 20N showed significant differences in nanoparticle capture profile at low pressure, consistent with literature data showing virus breakthrough under these conditions. Images obtained after a process interruption show significant migration of previously captured nanoparticles in the Planova 20N filters but not in the BioEX. These results provide important insights into the nature of virus capture in different virus filters and its dependence on the underlying structure of the virus filtration membranes.
Structural and Energetic Impact of Non‐natural 7‐Deaza‐8‐azaguanine, 7‐Deaza‐8‐azaisoguanine, and Their 7‐Substituted Derivatives on Hydrogen‐Bond Pairing with Cytosine and Isocytosine
Authors: Chawla Mohit , Minenkov Yury , Vu Khanh B. , Oliva Romina , Cavallo Luigi
Published: April 2019

The impact of 7‐deaza‐8‐azaguanine (DAG) and 7‐deaza‐8‐azaisoguanine (DAiG) modifications on the geometry and stability of the G:C Watson–Crick (cWW) base pair and the G:iC and iG:C reverse Watson–Crick (tWW) base pairs has been characterized theoretically. In addition, the effect on the same base pairs of seven C7‐substituted DAG and DAiG derivatives, some of which have been previously experimentally characterized, has been investigated. Calculations indicate that all of these modifications have a negligible impact on the geometry of the above base pairs, and that modification of the heterocycle skeleton has a small impact on the base‐pair interaction energies. Instead, base‐pair interaction energies are dependent on the nature of the C7 substituent. For the 7‐substituted DAG‐C cWW systems, a linear correlation between the base‐pair interaction energy and the Hammett constant of the 7‐substituent is found, with higher interaction energies corresponding to more electron‐withdrawing substituents. Therefore, the explored modifications are expected to be accommodated in both parallel and antiparallel nucleic acid duplexes without perturbing their geometry, while the strength of a base pair (and duplex) featuring a DAG modification can, in principle, be tuned by incorporating different substituents at the C7 position.
Agar versus Agarose Gelled Electrolyte for In Situ Corrosion Studies on Metallic Cultural Heritage
Authors: Ramírez Barat Blanca , Cano Emilio
Published: April 2019

The use of gelled electrolytes has revealed an interesting solution for in situ electrochemical measures on cultural heritage, where liquid electrolytes cannot be easily handled. After developing an agar gelled electrolyte cell, other gelling agents such as agarose are being considered to improve it. In this work, the performance of agarose gels in different concentrations has been studied and compared to agar and a liquid electrolyte. Measurements have been done on patinated quaternary bronze and weathering steel, as representative materials of outdoor monuments. Agarose gels have been validated for in situ corrosion studies on bronze and weathering steel sculptures.
Synthesis of Off‐Stoichiometric CoS Nanoplates from a Molecular Precursor for Efficient H2/O2 Evolution and Supercapacitance
Authors: Gervas Charles , Khan Malik Dilshad , Mlowe Sixberth , Zhang Chunyang , Zhao Chen , Gupta Ram K. , Akerman Matthew P. , Mashazi Philani , Nyokong Tebello , Revaprasadu Neerish
Published: April 2019

The development of cost‐effective and easily accessible bifunctional materials, which can be effectively used for energy storage and energy generation, is highly desirable. Herein, a new molecular precursor [tris(morpholinodithiocarbamato)Co(III)] has been synthesized and the X‐ray crystal structure of the complex determined. The precursor was used to prepare oleylamine (OLA)‐capped cobalt sulfide nanoplatelets, using a facile hot injection method at two different temperatures (200 °C and 260 °C). The characterization of the samples shows that CoS synthesized at 200 °C is slightly sulfur rich, whereas CoS synthesized at 260 °C is slightly cobalt rich. The effect of off‐stoichiometry of CoS nanoplatelets on the energy generation and storage applications was studied. The oxygen evolution reaction catalytic performance of both samples indicate overpotentials of 307 and 276 mV as well as Tafel slopes of 96 and 82 mV/dec, respectively. Similarly, overpotentials of 132 and 153 mV were observed for the hydrogen evolution reaction, with Tafel slopes of 159 and 154 mV/dec, respectively. The capacitive behavior of the samples was also examined, and specific capacitance values of 298 and 440 F/g were obtained with cycling stabilities of 73 and 97 %, after 5000 cycles, respectively. The results indicate that sulfur‐deficient CoS can show superior performance for efficient energy generation and storage devices.
Nanoscale Perovskites as Catalysts and Supports for Direct Methanol Fuel Cells
Authors: Li Luyao , Tan Sha , Salvatore Kenna L. , Wong Stanislaus S.
Published: April 2019

With the ultimate goal of simultaneously finding cost‐effective, more earth‐abundant, and high‐performance alternatives to commercial Pt/Pd‐based catalysts for electrocatalysis, this review article highlights advances in the use of perovskite metal oxides as both catalysts and catalyst supports towards the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) within a direct methanol fuel cell (DMFC) configuration. Specifically, perovskite metal oxides are promising as versatile functional replacements for conventional platinum‐group metals, in part because of their excellent ionic conductivity, overall resistance to corrosion, good proton‐transport properties, and potential for interesting acidic surface chemistry, all of which contribute to their high activity and reasonable stability, especially within an alkaline electrolytic environment.
Azaarene Dimers
Authors: Hahn Sebastian , Butscher Julian , An Qingzhi , Jocic Angelina , Tverskoy Olena , Richter Marcus , Feng Xinliang , Rominger Frank , Vaynzof Yana , Bunz Uwe H. F.
Published: April 2019

Binaphthyl‐3,3′,4,4′‐tetraone was prepared and coupled to different bis(TIPS‐ethynyl)‐substituted (TIPS=triisopropyl silane) aromatic diamines, resulting in the formation of dimeric benzo‐fused azaacenes, centrally connected by a single bond. The two halves of the molecules are highly twisted with respect to each other and showed limited electronic interaction in the ground state because their absorption spectra remained very similar to those of the constituting monomers. The dimers displayed greatly reduced fluorescence when compared to the monomers, suggesting that there is a significant interaction of the two azarene units in the excited state. Preliminary investigations showed that the dimers are attractive for application as acceptors in organic photovoltaic because they significantly outperform their monomeric counterparts.
Pathfinders in oncology from the end of the 19th century to the first description of Ewing sarcoma
Authors: Hajdu Steven I.
Published: April 2019

During the period 1884 to 1922, the only option in cases of operable cancers was radical surgery, and only a minority of patients were cured. Sporadic attempts were made to treat inoperable cancer patients with bacterial toxins; however, with the discovery of x‐ray and radium, the era of radiation treatment as an alternative to surgery began. The discovery of transmissible cancers and experimental growth of cancer cells offered new information and not only led to a better understanding of the cellular composition of cancers but also yielded important information that ultimately paved the way to chemotherapy. These efforts also advanced the understanding of the pathogenesis of tumors and induced new clinical and pathologic classifications and subspecializations. It is important to emphasize that many of the initiatives and discoveries made in Europe in the second half of the 19th century were first put into clinical practice in the United States during the first 2 decades of the 20th century, including the use of x‐ray and radium for irradiation and as diagnostic tools. All things considered, the progress made between 1884 and 1922 came about through the hard work of many eminent individuals; however, there were 7 foresighted pathfinders (3 surgeons, 2 pathologists, 1 internist, and 1 physicist) who—despite their widely diverse backgrounds, personalities, and expertise—made remarkable contributions to oncology to an extent that is still felt today.
Aggregation‐Induced Emission‐Based Sensing Platform for Selective Detection of Zn2+: Experimental and Theoretical Investigations
Authors: Naskar Barnali , Dhara Anamika , Maiti Dilip K. , Kukułka Mercedes , Mitoraj Mariusz P. , Srebro‐Hooper Monika , Prodhan Chandraday , Chaudhuri Keya , Goswami Sanchita
Published: April 2019

Fluorescent chemosensors with aggregation induced emission enhancement (AIEE) emerge as promising tools in the field of sensing materials. Herein, we report the design, synthesis and applicability of a Schiff base chemosensor 1‐(benzo[1,3]dioxol‐4‐ylmethylene‐hydrazonomethyl)‐naphthalen‐2‐ol (Hbdhn) of AIE characteristics that exhibits highly effective and selective response towards Zn2+. The sensing effect of Hbdhn was evaluated by means of absorption/emission spectra and corresponding underlying photophysical mechanisms were proposed based on extensive quantum‐chemical (TD)DFT calculations. The aggregated states in different DMSO/H2O ratios and in a presence of Zn2+ were examined by fluorescence lifetime measurements, dynamic light scattering and scanning electron microscopy studies. The bioimaging abilities of Hbdhn were evaluated for Zn2+ in HepG2 cancer cells. The results demonstrate instant, stable in time and reproducible, colorimetric turn‐on response with superb selectivity and sensitivity of Hbdhn towards Zn2+, based on chelation enhanced fluorescence mechanism. AIEE improves further Hbdhn properties, leading to strong, long‐lived fluorescence, with appearance of rod‐like particles, in 90 % of water in DMSO and only 10 % of water in DMSO in the presence of Zn2+. All these features combined with successful biomaging studies make Hbdhn one of the most promising candidate for practical applications among recently proposed related systems.
Can Cyanuric Acid and 2,4,6‐Triaminopyrimidine Containing Ribonucleosides be Components of Prebiotic RNA? Insights from QM Calculations and MD Simulations
Authors: Kaur Sarabjeet , Sharma Purshotam , Wetmore Stacey D.
Published: April 2019

As a step toward assessing their fitness as pre‐RNA nucleobases, we employ DFT and MD simulations to analyze the noncovalent interactions of cyanuric acid (CA) and 2,4,6‐triaminopyrimidine (TAP), and the structural properties of the associated ribonucleosides (rNs) and oligonucleotides. Our calculations reveal that the TAP : CA pair has a comparable hydrogen‐bond strength to the canonical A : U pair. This strengthens the candidature of CA and TAP as prebiotic nucleobases. Further, the stacking between two canonical nucleobases is stronger than those between TAP or CA and a canonical base, as well as those between two TAP and/or CA, which indicates that enhanced stacking may have served as a driving force for the evolution from prebiotic to canonical nucleobases. Similarities in the DFT‐derived anti/syn rotational barriers and MD‐derived (anti) glycosidic conformation of the CA and TAP rNs and canonical rNs further substantiate their candidature as pre‐RNA components. Greater deglycosylation barriers (as obtained by DFT calculations) for TAP rNs compared to canonical rNs suggest TAP rNs indicate higher resistance to environmental factors, while lower barriers indicate that CA rNs were likely more suitable for less‐challenging locations. Finally, the tight packing in narrow CA:TAP‐containing helices suggests that the prebiotic polymers were shielded from water, which would aid their evolution into self‐replicating systems. Our calculations thus support proposals that CA and TAP can act as nucleobases of pre‐RNA.