bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Developments of Laser Desorption Ionization Mass Spectrometry in Natural Products Research
Authors: Schinkovitz Andreas , Séraphin Denis , Richomme Pascal 
Published: June 2019

Abstract
Mass spectrometry (MS) represents an indispensable tool for the structural identification of natural products (NPs) and is one of the major focus areas of analytical chemistry research. The technique has long been used to obtain molecular weights and further molecular formulae. In the past, former ionization sources such as electronic impact (EI) limited MS analysis to predominately volatile, polar, and thermostable compounds. However, the development of soft ionization techniques such as electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and laser desorption/ionization (LDI) have gradually extended the scope of MS analysis to a much wider range of chemical entities. Moreover, the hyphenation of liquid and gas chromatography with MS (LC‐MS, GC‐MS) has provided a most powerful tool for the analysis of complex mixtures and NPs. In fact, LC‐MS is often considered as a method of first choice particularly when studying complex mixtures of small molecules. On the other hand, recent developments in matrix‐assisted laser desorption/ionization (MALDI) and LDI may provide useful supplements and potential alternatives to this approach. Both methods share similar, though slightly different ionization mechanisms. While MALDI uses small molecules comprising strong UV chromophores (matrices) to transfer laser energy to the sample material, LDI targets compounds that can be directly ionized by laser irradiation without any matrix support. Moreover, certain compounds showing LDI properties may also work as MALDI matrices. With regard to NPs research, MALDI and LDI may help overcoming certain limitations encountered in LC‐MS such as the indispensable use of buffer solutions when analyzing alkaloids. Moreover, as (MA)LDI hardly requires any sample conditioning, analysis time can be significantly shortened.
With all this in mind, the subsequent article will highlight some interesting MALDI and LDI applications, which focus on the detection of NPs in complex mixtures. This includes the use of specifically adapted matrices for the selective detection of alkaloids (i), the study of the inherent LDI and matrix properties of phenolic compounds (ii) as well of evaluation on the reproducibility of LDI signal patterns (iii). Eventually, a statistical approach toward LDI profiling, which may provide a future tool for quality control of large sample batches will be presented (iv).
Triplet vinylnitrenes
Authors: Banerjee Upasana , Thenna‐Hewa Kosala , Gudmundsdottir Anna D. 
Published: June 2019

Abstract
This chapter describes how intramolecular sensitization has been used to successfully form triplet vinylnitrene intermediates from vinyl azide, isoxazole, and azirine compounds. Triplet vinylnitrenes have been thoroughly characterized in cryogenic matrices using UV/vis absorption, infrared, and electron spin resonance spectroscopies. Electron spin resonance spectroscopy shows that vinylnitrenes have a significant 1,3‐biradical character, which is further supported by density functional theory calculations. Laser flash photolysis, which has allowed the direct detection of triplet vinylnitrenes in solution, reveals that they are short‐lived intermediates with lifetimes on the order of a few microseconds. Vinylnitrenes decay efficiently by intersystem crossing to form products because their 1,3‐biradical character renders their vinylic CC bond flexible, which enhances intersystem crossing. At cryogenic temperatures, flexible triplet vinylnitrenes are not stable and intersystem cross to form products. Nevertheless, triplet vinylnitrenes can be stabilized by limiting the flexibility of the vinylic CC bond, which renders them stabile in cryogenic matrices. Thus, they are promising building blocks for high‐spin assemblies. Furthermore, as stabilized vinylnitrenes can also be employed in bimolecular reactions, they have potential for use in various synthetical applications.
In Situ Observation of Crystallization Dynamics and Grain Orientation in Sequential Deposition of Metal Halide Perovskites
Authors: Meng Ke , Wang Xiao , Xu Qiaofei , Li Zhimin , Liu Zhou , Wu Longlong , Hu Youdi , Liu Ning , Chen Gang 
Published: June 2019

AbstractMetal halide perovskites have revolutionized the development of highly efficient, solution‐processable solar cells. Further advancements rely on improving perovskite film qualities through a better understanding of the underlying growth mechanism. Here, a systematic in situ grazing‐incidence X‐ray diffraction investigation is performed, facilitated by other techniques, on the sequential deposition of formamidinium lead iodide (FAPbI3)‐based perovskite films. The active chemical reaction, composition distribution, phase transition, and crystal grain orientation are all visualized following the entire perovskite formation process. Furthermore, the influences of additive ions on the crystallization speed, grain orientation, and morphology of FAPbI3‐based films, along with their photovoltaic performances, are fully evaluated and optimized, which leads to highly reproducible and efficient perovskite solar cells. The findings provide key insights into the perovskite growth mechanism and suggest the fabrication of high‐quality perovskite films for widespread optoelectronic applications.
Highly Sensitive Temperature Sensor: Ligand‐Treated Ag Nanocrystal Thin Films on PDMS with Thermal Expansion Strategy
Authors: Bang Junsung , Lee Woo Seok , Park Byeonghak , Joh Hyungmok , Woo Ho Kun , Jeon Sanghyun , Ahn Junhyuk , Jeong Chanho , Kim Tae‐il , Oh Soong Ju 
Published: June 2019

AbstractHighly sensitive temperature sensors are designed by exploiting the interparticle distance–dependent transport mechanism in nanocrystal (NC) thin films based on a thermal expansion strategy. The effect of ligands on the electronic, thermal, mechanical, and charge transport properties of silver (Ag) NC thin films on thermal expandable substrates of poly(dimethylsiloxane) (PDMS) is investigated. While inorganic ligand‐treated Ag NC thin films exhibit a low temperature coefficient of resistance (TCR), organic ligand‐treated films exhibit extremely high TCR up to 0.5 K−1, which is the highest TCR exhibited among nanomaterial‐based temperature sensors to the best of the authors' knowledge. Structural and electronic characterizations, as well as finite element method simulation and transport modeling are conducted to determine the origin of this behavior. Finally, an all‐solution based fabrication process is established to build Ag NC‐based sensors and electrodes on PDMS to demonstrate their suitability as low‐cost, high‐performance attachable temperature sensors.
Light‐Induced Swelling‐Responsive Conductive, Adhesive, and Stretchable Wireless Film Hydrogel as Electronic Artificial Skin
Authors: Ryplida Benny , Lee Kang Dae , In Insik , Park Sung Young 
Published: June 2019

AbstractLight‐induced wireless soft electronic skin hydrogels with excellent mechanical and electronic properties are important for several applications, such as soft robotics and intelligent wearable devices. Precise control of reversible stretchability and capacitive properties depending on intermolecular interaction and surface characteristics remains a challenge. Here, a thin‐film hydrogel is designed based on titanium oxide (TiO2) polydopamine–perfluorosilica carbon dot‐conjugated chitosan–polyvinyl alcohol‐loaded tannic acid with controllable hydrophobic–hydrophilic transition in the presence of UV–vis light irradiation. The shifting of surface wettability from hydrophobic to hydrophilic by irradiation affects thin‐film water permeability and swelling ratio. This allows the penetration of water into the matrix to change its mechanical strength, electronic properties, and adhesive behavior. Specifically, the hydrogel displays mechanical strain as high as 278% in response to light stimuli and demonstrates the ability to regain its initial state determining the elasticity of the fabricated material. Moreover, the thin‐film hydrogel shows an increase in conductivity to 1.096 × 10−3 and 1.026 × 10−3 S cm−1 when irradiated with UV and visible light, respectively. The hydrogel exhibits capacitive reversibility that follows finger motion which can be identified directly or remotely using wireless connection, indicative of its possible applications as an artificial electronic skin.
A Textile Platform Using Continuous Aligned and Textured Composite Microfibers to Engineer Tendon‐to‐Bone Interface Gradient Scaffolds
Authors: Calejo Isabel , Costa‐Almeida Raquel , Reis Rui L. , Gomes Manuela E. 
Published: June 2019

AbstractTendon‐to‐bone interfaces exhibit a hierarchical multitissue transition. To replicate the progression from mineralized to nonmineralized tissue, a novel 3D fibrous scaffold is fabricated with spatial control over mineral distribution and cellular alignment. For this purpose, wet‐spun continuous microfibers are produced using polycaprolactone (PCL)/ gelatin and PCL/gelatin/hydroxyapatite nano‐to‐microparticles (HAp). Higher extrusion rates result in aligned PCL/gelatin microfibers while, in the case of PCL/gelatin/HAp, the presence of minerals leads to a less organized structure. Biological performance using human adipose‐derived stem cells (hASCs) demonstrates that topography of PCL/gelatin microfibers can induce cytoskeleton elongation, resembling native tenogenic organization. Matrix mineralization on PCL/gelatin/HAp wet‐spun composite microfibers suggest the production of an osteogenic‐like matrix, without external addition of osteogenic medium supplementation. As proof of concept, a 3D gradient structure is produced by assembling PCL/gelatin and PCL/gelatin/HAp microfibers, resulting in a fibrous scaffold with a continuous topographical and compositional gradient. Overall, the feasibility of wet‐spinning for the generation of continuously aligned and textured microfibers is demonsrated, which can be further assembled into more complex 3D gradient structures to mimic characteristic features of tendon‐to‐bone interfaces.
Activating C‐Coordinated Iron of Iron Hexacyanoferrate for Zn Hybrid‐Ion Batteries with 10 000‐Cycle Lifespan and Superior Rate Capability
Authors: Yang Qi , Mo Funian , Liu Zhuoxin , Ma Longtao , Li Xinliang , Fang Daliang , Chen Shimou , Zhang Suojiang , Zhi Chunyi 
Published: June 2019

AbstractPrussian blue analogue (PBA)‐type metal hexacyanoferrates are considered as significant cathodes for zinc batteries (ZBs). However, these PBA‐type cathodes, such as cyanogroup iron hexacyanoferrate (FeHCF), suffer from ephemeral lifespan (≤1000 cycles), and inferior rate capability (1 A g−1). This is because the redox active sites of multivalent iron (Fe(III/II)) can only be very limited activated and thus utilized. This is attributed to the spatial resistance caused by the compact cooperation interaction between Fe and the surrounded cyanogroup, and the inferior conductivity. Here, it is found that high‐voltage scanning can effectively activate the C‐coordinated Fe in FeHCF cathode in ZBs. Thanks to this activation, the Zn–FeHCF hybrid‐ion battery achieves a record‐breaking cycling performance of 5000 (82% capacity retention) and 10 000 cycles (73% capacity retention), respectively, together with a superior rate capability of maintaining 53.2% capacity at superhigh current density of 8 A g−1 (≈97 C). The reversible distortion and recovery of the crystalline structure caused by the (de)insertion of zinc and lithium ions is revealed. It is believed that this work represents a substantial advance on PBA electrode materials and may essentially promote application of PBA materials.
Thermal Metamaterials with Site‐Specific Thermal Properties Fabricated by 3D Magnetic Printing
Authors: Ren Luquan , Zhou Xueli , Xue Jingze , Song Zhengyi , Li Bingqian , Liu Qingping , Zhao Che 
Published: June 2019

AbstractRecently, composites with global anisotropic thermal properties, including thermal conductivity and thermal expansion, have drawn increasing attention as promising thermal‐management materials for highly integrated electrical devices. However, fabricating thermal metamaterials with site‐specific thermal properties remains a great challenge. A 3D magnetic printing process to fabricate fiber‐reinforced composites with site‐specific thermal properties by controlling the orientation of the fibers is presented. In proof‐of‐concept experiments, nickel‐coated carbon fibers (NiCFs) dispersed in resin are site‐specifically aligned according to predesigned patterns through design of the magnet trajectory plan. Composites with aligned fibers are fabricated resulting in site‐specific thermal conductivity that can be locally modulated by a factor of up to 1.39, which is mainly attributable to the aligned NiCFs that can form thermal conductive pathways for phonon transport along the direction of the aligned fibers. These results demonstrate that the thermal properties of composites can be controlled by adjusting the orientation of the fibers. Finally, the present method is applied to fabricate a site‐specific thermal metamaterial as a proof‐of‐concept thermal control. The proposed strategy takes full advantage of 3D‐printing technology, opening a new avenue for manufacturing composites with programmable thermal conductivity, which is thus far inaccessible by traditional manufacturing technologies.
Thin Hydrogel–Elastomer Multilayer Encapsulation for Soft Electronics
Authors: Macron Jennifer , Gerratt Aaron P. , Lacour Stéphanie P. 
Published: June 2019

AbstractIn the exciting race to design and engineer biointegrated and body‐like electronic systems, many efforts concentrate on the integration of hydrogels in electronic assemblies. The versatility of hydrogels chemistry combined with their tissue‐mimicking properties inspires numerous demonstrations of hydrogel‐based touch panels, robots, and sensors over the years. However, their long‐term integration in a thin and functional electronic assembly remains a challenge: their sensitivity to both air‐drying and water swelling leads to important volume change of the network that is incompatible with the cohesion of a multilayer system, and has irreversible impact on the electronic properties of the assembly. To tackle this issue, proposed is a method to fabricate a hydrogel–elastomer micrometric bilayer with a stable interface, using of a low‐swelling type of hydrogel, i.e., poly(2‐hydroxyethyl methacrylate) and silicone rubber. The bilayer can sustain multiple hydration/dehydration cycles without delamination and can be kept for several months in its dry configuration. Combined with soft metallization technology, the bilayer can be readily integrated into a soft electronic circuit thereby opening a technological route for microfabricated, on‐demand morphing systems.
Switching between Copper‐Catalysis and Photocatalysis for Tunable Halofluoroalkylation and Hydrofluoroalkylation of 1,6‐Enynes toward 1‐Indenones
Authors: Shen Zheng‐Jia , Wang Shi‐Chao , Hao Wen‐Juan , Yang Shi‐Zhao , Tu Shu‐Jiang , Jiang Bo 
Published: June 2019

AbstractTunable halofluoroalkylation and hydrofluoroalkylation of 1,6‐enynes were first reported by switching between copper‐catalysis and photocatalysis, leading to the atom‐economic and highly stereoselective protocols toward functionalized 1‐indenones with moderate to good yields. Copper‐catalysis enabled the concomitant incorporation of two important fluoroalkyl and halo functionalities into 1‐indenone skeleton, in which fluoroalkyl bromides were transformed into (E)‐1‐indenones as a major stereoisomer while fluoroalkyl iodides oriented complete Z‐selectivity to access (Z)‐1‐indenones. Specifically, photocatalysis allowed hydrofluoroalkylation of 1,6‐enynes to access fluoroalkylated (Z)‐1‐indenones under mild conditions, in which THF behaved as a hydrogen source. These two approaches feature remarkable compatibility with a wide variety of 1,6‐enynes and fluoroalkyl halides and excellent atomic utilization.magnified image
Nanoengineering of Mesenchymal Stem Cells via Surface Modification for Efficient Cancer Therapy
Authors: Layek Buddhadev , Sehgal Drishti , Argenta Peter A. , Panyam Jayanth , Prabha Swayam 
Published: June 2019

AbstractMesenchymal stem cells (MSCs) can be used for tumor‐specific delivery of small molecular weight anticancer drugs by using nanoparticle‐encapsulated forms of the drugs. Current approaches to incorporate nanoparticles in MSCs rely on nonspecific endocytosis of nanoparticles or their conjugation to the cell surface via endogenous amines and thiols. These methods result in sub‐optimal drug loading, which hinders the widespread application of MSCs as drug carriers. An advanced nanoengineering strategy is reported here that involves generation of MSCs expressing azide functional groups on their surface and conjugation of dibenzyl cyclooctyne‐functionalized nanoparticles to the azide groups using copper‐free click chemistry. This novel strategy significantly improves the payload capacity of MSCs (≈48 pg of paclitaxel (PTX) per cell) relative to that reported previously (<1–20 pg per cell), without affecting their native phenotype. In vivo, the nanoengineered MSCs significantly inhibit tumor growth (p < 0.05) and improve survival (p < 0.0001) compared to free or nanoparticle encapsulated PTX and Abraxane in an orthotopic ovarian tumor model. In summary, the nanoengineering strategy reported here allows for improved delivery and anticancer efficacy of conventional chemotherapeutic agents using MSCs as drug carriers.
Social mobility of the father influences child growth: A three‐generation study
Authors: Koziel Slawomir , Zaręba Monika , Bielicki Tadeusz , Scheffler Christiane , Hermanussen Michael 
Published: June 2019

AbstractObjectivesThe association between body height and social status is known. We were interested in the effect of intergeneration changes in social status on height.MethodsBody height was measured in 2008 paternal grandfather‐father‐son and 1803 paternal grandfather‐father‐daughter triplets. The sample consisted of four child cohorts born in 1988, 1985, 1983, and 1980, and was measured annually from 6 to 11, 9 to 14, 11 to 16, and 14 to 18 years of age. Triplets were dichotomized according to grandfathers' occupation, into one “lower” and one “upper” grandparental class; and according to paternal education, into one “lower” and “upper” paternal class, resulting in four “family histories”: two nonmobile (grandfathers and fathers stayed in the same social class), and two mobile histories (social class of fathers and grandfathers differed).Results“Upper” class fathers are taller than “lower” class fathers. This class effect on height persists into the third generation. Upward social mobility (“lower” class fathers receive secondary or university education) results in taller stature both in the fathers and in the children. The opposite applies for downward social mobility. “Upper” class fathers with only basic or vocational education lose the social advantage and remain shorter. So do their children.ConclusionsThe class effect on height tends to persist into the next generation, but depends on education. Upward social mobility measured as a “better” education, results in taller stature, up to the third generation. The study highlights the importance of education as a major regulator of body height.
Positionen von Spinellfehlstellen in γ‐Al2O3
Authors: Prins Roel 
Published: June 2019

AbstractEin Nicht‐Spinellmodell für die Struktur von γ‐Al2O3, bei dem sich 25 % der Al3+‐Kationen an tetraedrischen Positionen befinden, hat viel Interesse erregt. 17O‐NMR‐Messungen und – erst kürzlich – 27Al‐NMR‐Messungen haben aber gezeigt, dass sich erheblich mehr Al3+‐Kationen an tetraedrischen Positionen befinden. Dies bedeutet, dass sich die Al3+‐Fehlstellen in γ‐Al2O3 nicht an tetraedrischen, sondern an oktaedrischen Positionen befinden, wie beim isostrukturellen γ‐Fe2O3 und in Übereinstimmung mit dichtefunktionaltheoretischen Voraussagen. Dies hat Folgen für die Struktur der γ‐Al2O3‐Oberfläche und für die Katalyse.
Tri‐Spiral Donor for High Efficiency and Versatile Blue Thermally Activated Delayed Fluorescence Materials
Authors: Li Wei , Li Binbin , Cai Xinyi , Gan Lin , Xu Zhida , Li Wenqi , Liu Kunkun , Chen Dongcheng , Su Shi‐Jian 
Published: June 2019

AbstractBlue thermally activated delayed fluorescence (TADF) emitters that can simultaneously achieve high efficiency in doped and nondoped organic light‐emitting diodes (OLEDs) are rarely reported. Reported here is a strategy using a tri‐spiral donor for such versatile blue TADF emitters. Impressively, by simply extending the nonconjugated fragment and molecular length, aggregation‐caused emission quenching (ACQ) can be greatly alleviated to achieve as high as a 90 % horizontal orientation dipole ratio and external quantum efficiencies (EQEs) of up to 33.3 % in doped and 20.0 % in nondoped sky‐blue TADF‐OLEDs. More fascinatingly, a high‐efficiency purely organic white OLED with an outstanding EQE of up to 22.8 % was also achieved by employing TspiroS‐TRZ as a blue emitter and an assistant host. This compound is the first blue TADF emitter that can simultaneously achieve high electroluminescence (EL) efficiency in doped, nondoped sky‐blue, and white TADF‐OLEDs.
Chemo‐ and Enantioselective Hydrogenation of α‐Formyl Enamides: An Efficient Access to Chiral α‐Amido Aldehydes
Authors: Zhang Jian , Jia Jia , Zeng Xincheng , Wang Yuanhao , Zhang Zhenfeng , Gridnev Ilya D. , Zhang Wanbin 
Published: June 2019

AbstractIn order to effectively synthesize chiral α‐amino aldehydes, which have a wide range of potential applications in organic synthesis and medicinal chemistry, a highly chemo‐ and enantioselective hydrogenation of α‐formyl enamides has been developed, catalyzed by a rhodium complex of a P‐stereogenic bisphosphine ligand. Under different hydrogen pressures, the chiral α‐amido aldehydes and β‐amido alcohols were obtained in high yields (97–99 %) and with excellent chemo‐ and enantioselectivities (up to >99.9 % ee). The hydrogenation can be carried out on a gram scale and with a high substrate/catalyst ratio (up to 20 000 S/C), and the hydrogenated products were further converted into several important chiral products. Computations of the catalytic cycle gave a clear description for the R/S pathways, provided a reasonable explanation for the enantioselectivity, and revealed several other specific features.
Location of the Spinel Vacancies in γ‐Al2O3
Authors: Prins Roel 
Published: June 2019

AbstractA non‐spinel model for the structure of γ‐Al2O3, with 25 % of the Al3+ cations at tetrahedral positions, has been the subject of wide interest. However, 17O NMR measurements and, more recently, 27Al NMR measurements have shown that there are considerably more Al3+ cations at tetrahedral positions. This means that the Al3+ vacancies in γ‐Al2O3 are not at tetrahedral but at octahedral positions, as in isostructural γ‐Fe2O3 and in accordance with density functional theory predictions. This has consequences with regard to the surface structure of γ‐Al2O3, and thus, for catalysis.
Switchable Reversible Addition–Fragmentation Chain Transfer (RAFT) Polymerization with the Assistance of Azobenzenes
Authors: Nie Huijun , Li Shenzhen , Qian Sijia , Han Zhongqiang , Zhang Wangqing 
Published: June 2019

AbstractModulating controlled radical polymerization is an interesting and important issue. Herein, modulating RAFT polymerization employing photosensitive azobenzenes is achieved. In the presence of azobenzenes and with visible light off, RAFT polymerization runs smoothly and follows a pseudo‐first‐order kinetics. In contrast, with light on, RAFT polymerization is greatly decelerated or quenched depending on the type and concentration of azobenzenes. Switchable RAFT polymerization of different (meth)acrylate monomers alternatively with light off and on is demonstrated. A mechanism of photoregulating RAFT polymerization involving radical quenching by azobenzenes is proposed.