bluuebunny/crossref_metadata_2025_split huggingface dataset:
4,5‐Diazafluorene‐Based Donor–Acceptor Small Molecules as Charge Trapping Elements for Tunable Nonvolatile Organic Transistor Memory
Authors: Yu Yang , Bian Lin‐Yi , Chen Jian‐Guo , Ma Qi‐Hao , Li Yin‐Xiang , Ling Hai‐Feng , Feng Quan‐You , Xie Ling‐Hai , Yi Ming‐Dong , Huang Wei 
Published: September 2018

AbstractThree diazafluorene derivatives triphenylamine (TPA)(PDAF)n (n = 1, 2, 3) serving as small molecular elements are designed and synthesized via concentrated sulfuric acid mediated Friedel–Crafts reaction. With highly nonplanar topological configuration, TPA(PDAF)3 shows weaker intermolecular interaction in the solid states and thus exhibits single nanomolecular behavior, which is crucial for charge stored and retained in an organic field‐effect transistor (OFET) memory device. Furthermore, diazafluorene derivatives possess a completely separate highest occupied molecular orbital/lowest unoccupied molecular orbital, which offers ideal hole and electron trapping sites. As charge storage elements, triphenylamine groups provide the hole trapping sites, while diazafluorene units provide the electron trapping sites and act as a hole blocking group to restrain the leakage of stored holes trapped in triphenylamine. The pentacene‐based OFET memory device with solution‐processing TPA(PDAF)3 shows a good hole‐trapping ability, high hole trapping density (4.55 × 1012 cm−2), fast trapping speed (<20 ms), a large memory window (89 V), and a tunable ambipolar memory behavior. The optimized device shows a large ON/OFF current ratio (2.85 × 107), good charge retention (>104 s), and reliable endurance properties. This study suggests that diazafluorene based donor–acceptor small molecular elements have great promise for high‐performance OFET memory.
A Modular Approach to Sensitized Two‐Photon Patterning of Photodegradable Hydrogels
Authors: Lunzer Markus , Shi Liyang , Andriotis Orestis G. , Gruber Peter , Markovic Marica , Thurner Philipp J. , Ossipov Dmitri , Liska Robert , Ovsianikov Aleksandr 
Published: September 2018

AbstractPhotodegradable hydrogels have emerged as useful platforms for research on cell function, tissue engineering, and cell delivery as their physical and chemical properties can be dynamically controlled by the use of light. The photo‐induced degradation of such hydrogel systems is commonly based on the integration of photolabile o‐nitrobenzyl derivatives to the hydrogel backbone, because such linkers can be cleaved by means of one‐ and two‐photon absorption. Herein we describe a cytocompatible click‐based hydrogel containing o‐nitrobenzyl ester linkages between a hyaluronic acid backbone, which is photodegradable in the presence of cells. It is demonstrated for the first time that by using a cyclic benzylidene ketone‐based small molecule as photosensitizer the efficiency of the two‐photon degradation process can be improved significantly. Biocompatibility of both the improved two‐photon micropatterning process as well as the hydrogel itself is confirmed by cell culture studies.
Electrocatalytic properties of diiron ethanedithiolate complexes containing benzoate ester
Authors: Chen Fei‐Yan , He Jiao , Yu Xiao‐Yong , Wang Zheng , Mu Chao , Liu Xu‐Feng , Li Yu‐Long , Jiang Zhong‐Qing , Wu Hong‐Ke 
Published: September 2018

Six diiron ethanedithiolate complexes containing benzoate ester have been synthesized and characterized. Treatment of the starting material [{μ‐SCH2CH(CH2OH)S}Fe2(CO)6] (1) with benzoic acid in the presence of N,N′‐dicyclohexylcarbodiimide and 4‐dimethylaminopyridine afforded the benzoate ester‐containing complex [{μ‐SCH2CH(CH2O2CPh)S}Fe2(CO)6] (2) in 97% yield. Carbonyl substitution of complex 2 with a monophosphine ligand, such as triphenylphosphine, tris(2‐methoxyphenyl)phosphine, tris(4‐fluorophenyl)phosphine, isopropyldiphenylphosphine or cyclohexyldiphenylphosphine, in the presence of Me3NO⋅2H2O gave the derivatives [{μ‐SCH2CH(CH2O2CPh)S}Fe2(CO)5L] (L = PPh3, 3; P(C6H4OCH3‐2)3, 4; P(C6H4F‐4)3, 5; Ph2PCH(CH3)2, 6; Ph2PC6H11, 7) in 66–95% yields. Complexes 2–7 were characterized using elemental analysis, spectroscopy and X‐ray diffraction analysis. In addition, these complexes can catalyze the reduction of protons to H2 in the presence of weak acid HOAc under electrochemical conditions.
Bivalve sanctuaries to enhance stocks along the Algarve coast of southern Portugal: A spatio‐temporal approach
Authors: Rufino Marta M. , Vasconcelos Paulo , Pereira Fábio , Moura Paula , Gaspar Miguel B. 
Published: September 2018

Abstract

Populations of marine bivalves are subject to large interannual fluctuations as a result of their sensitivity to unfavourable environmental conditions. These populations have a strong dependence on recruitment, which constitutes a risk to stock conservation and the sustainability of the commercially exploited species. Bivalve sanctuaries comprising no‐take areas can promote the restocking of large coastal areas as a result of the high fecundity and the potentially long‐distance larval dispersal of bivalves.
The present study explores a novel spatio‐temporal approach to investigate suitable locations for bivalve sanctuaries, aimed at protecting and enhancing stocks along the Algarve coast in southern Portugal. In the context of small‐scale fisheries, bivalve dredging constitutes an important socio‐economic activity. Three bivalve species are targeted: the striped venus (Chamelea gallina), the donax clam (Donax trunculus), and the surf clam (Spisula solida).
Data gathered from 36 bivalve fishing surveys conducted over three decades (1986–2015) were analysed using geostatistical methods, accounting for temporal and spatial autocorrelation to produce continuous prediction maps of species distribution for each survey. The approach taken permitted the use of all scattered historical data collected by different methods. The predictions were then used to summarize and illustrate the spatial distribution of species across time, in terms of average biomass, variability, and maximum potential biomass, and to delimit the areas as a function of the species persistence (recurrent, occasional, or rare). The temporal patterns through space were further investigated using empirical orthogonal function (EOF) analysis. The areas accounting for 80% of the species biomass were also estimated.
Results of this set of analyses led to the proposal of locations for establishing bivalve sanctuaries, aimed at enhancing the stocks of commercial bivalve species in the long term. Such an innovative spatio‐temporal approach and management strategy is replicable in other fishing resources and geographic areas.
miR‐330‐3p promotes lung cancer cells invasion, migration, and metastasis by directly targeting hSOD2b
Authors: Shen Lianghua , Yi Shanze , Huang Luyuan , Li Shuaiguang , Bai Fang , Lei Sijia , Breitzig Mason , Czachor Alexander , Sun Hanxiao , Zheng Qing , Wang Feng 
Published: September 2018

AbstractLung cancer is a serious threat to human health. Studies have revealed that human manganese superoxide dismutase (hSOD2) and miRNAs play an essential role in the metastasis process of lung cancer. However, the miRNAs that associated with hSOD2 and involved in metastasis, remain elusive. After databases analysis and dual luciferase reporter validation, we demonstrated that miR‐330‐3p expression inversely correlated with hSOD2b expression level, and that miR‐330‐3p directly targeted the 3′untranslated region (3′UTR) of hSOD2b. Furthermore, overexpression of miR‐330‐3p promoted whereas knockdown of miR‐330‐3p inhibited invasion/migration and the epithelial–mesenchymal transition (EMT) process of lung cancer cells in vitro. Knockdown of miR‐330‐3p inhibited metastasis of lung cancer cells in vivo. Moreover, miR‐330‐3p‐mediated enhancement of invasion/migration in 95‐D cells could be rescued by over‐expression of hSOD2. In conclusion, we demonstrated that miR‐330‐3p promoted metastasis of lung cancer cells by suppressing hSOD2b expression and unveiled a new clinical application of miR‐330‐3p in the therapy of lung cancer.
C3−C3′ and C6−C6′ Oxidative Couplings of Carbazoles
Authors: Li Mao 
Published: September 2018

Abstract9‐Substituted carbazoles are widely used units in materials science, and their oxidative reactions have been utilized for the synthesis and characterization of polymers. Though the oxidative mechanism of carbazoles has been known for a few decades, structural definition has remained difficult, because their polymers are generally insoluble with incomplete characterization and unknown dependence of the electrochemical potentials. The oxidative reactions of 9‐substituted carbazoles should be carefully considered under specific oxidative conditions; otherwise, structure definitions could be wrong, because the IR and NMR spectra used previously cannot quantitatively analyze 3,3′‐coupling and 6,6′‐coupling of carbazoles. In this review, the best understanding of the C3−C3′ and C6−C6′ oxidative couplings of 9‐substituted carbazoles is presented, and the benefit of these oxidative reactions from the viewpoints of electrochemical synthesis, film engineering, and the synthesis and processing of polymers is highlighted.
Quadratic and Cubic Optical Nonlinearities of Y‐Shaped and Distorted‐H‐Shaped Arylalkynylruthenium Complexes
Authors: Morshedi Mahbod , Kodikara Mahesh S. , Corkery T. Christopher , Hurst Stephanie K. , Chavan Sanjay S. , Kulasekera Erandi , Stranger Rob , Samoc Marek , Van Cleuvenbergen Stijn , Asselberghs Inge , Clays Koen , Cifuentes Marie P. , Humphrey Mark G. 
Published: September 2018

AbstractStraightforward syntheses of bis[bis{1,2‐bis(diphenylphosphino)ethane}ruthenium]‐functionalized 1,3,5‐triethynylbenzene‐cored complexes via a methodology employing “steric control” permit facile formation of Y‐shaped Sonogashira coupling products and distorted‐H‐shaped homo‐coupled quadrupolar products. Cyclic voltammetric data from these products reveal two reversible metal alkynyl‐localized oxidation processes for all complexes. The wavelengths of the linear optical absorption maxima are dominated by the nature of the peripheral alkynyl ligand rather than the substituent at the unique arm of the “Y” or at the quadrupolar complex “core”. The quadratic optical nonlinearities of the Y‐shaped complexes were assessed by the hyper‐Rayleigh scattering technique at 800 nm and employing 100 fs light pulses; introduction of donor NEt2 and/or acceptor NO2 to the wedge periphery resulted in non‐zero nonlinearities, with the largest βHRS,800 values being observed for the complexes containing the 4‐nitrophenylalkynyl ligands. Depolarization ratios are consistent with substantial off‐diagonal first hyperpolarizability tensor components and 2D nonlinear character. Computational studies employing time‐dependent density functional theory have been employed to assign the key low‐energy transitions in the linear optical spectra and to compute the quadratic nonlinear optical tensorial components. Cubic optical nonlinearities of the quadrupolar complexes were assessed by the Z‐scan technique over the range 500–1600 nm and employing 130 fs light pulses; two‐photon absorption cross‐sections for these distorted‐H‐shaped complexes are moderate to large in value (up to 5500 GM at 880 nm), while one example displays significant three‐photon absorption (1300×10−80 cm6 s2 at 1200 nm).
Light‐Induced Spin Transitions in Copper‐Nitroxide‐Based Switchable Molecular Magnets: Insights from Periodic DFT+U Calculations
Authors: Sánchez‐de‐Armas Rocío , Cruz Hernández Norge , Calzado Carmen J. 
Published: September 2018

AbstractThe electronic structure and magnetic interactions of three members of the breathing crystal Cu(hfac)2LR family (hfac=hexafluoroacetylacetonato, LR=pyrazole‐substituted nitronyl nitroxides with R=Me, Et, Pr, iPr, Bu ), mainly Cu(hfac)2LPr (1), Cu(hfac)2LBu⋅0.5 C8H18 (2) and Cu(hfac)2LBu⋅0.5 C8H10 (3), have been analyzed by means of periodic plane‐wave based DFT+U calculations. These CuII‐nitroxide based molecular magnets display thermally and optically induced switchable behavior and light‐induced excited spin state trapping phenomena. The calculations confirm the presence of temperature‐dependent exchange interaction within the spin triads formed by the nitroxide‐copper(II)‐nitroxide units, in line with the changes observed in the effective magnetic moment. Moreover, they quantify the interchain interaction mediated by the terminal nitroxide group of two spin triads in neighboring polymer chains. This interaction competes with the exchange interaction within the spin triads at high temperature, and introduces 1D exchange channels that do not coincide with the polymeric chains. The density of states reveal that the low‐lying conduction states potentially involved in the UV/Vis transitions are located on the nitroxide radicals, the hfac groups and the Cu atoms. Then, the density of states is almost independent of the solvent and the R group. This suggests the possibility of light‐induced spin switching for other members of this family. The 500 nm band of the low‐temperature phase can be ascribed to a ligand‐to‐metal charge transfer transition between the nitroxide and Cu bands.
Modular Enzymatic Cascade Synthesis of Vitamin B5 and Its Derivatives
Authors: Abidin Mohammad Z. , Saravanan Thangavelu , Zhang Jielin , Tepper Pieter G. , Strauss Erick , Poelarends Gerrit J. 
Published: September 2018

AbstractAccess to vitamin B5 [(R)‐pantothenic acid] and both diastereoisomers of α‐methyl‐substituted vitamin B5 [(R)‐ and (S)‐3‐((R)‐2,4‐dihydroxy‐3,3‐dimethylbutanamido)‐2‐methylpropanoic acid] was achieved using a modular three‐step biocatalytic cascade involving 3‐methylaspartate ammonia lyase (MAL), aspartate‐α‐decarboxylase (ADC), β‐methylaspartate‐α‐decarboxylase (CrpG) or glutamate decarboxylase (GAD), and pantothenate synthetase (PS) enzymes. Starting from simple non‐chiral dicarboxylic acids (either fumaric acid or mesaconic acid), vitamin B5 and both diastereoisomers of α‐methyl‐substituted vitamin B5, which are valuable precursors for promising antimicrobials against Plasmodium falciparum and multidrug‐resistant Staphylococcus aureus, can be generated in good yields (up to 70 %) and excellent enantiopurity (>99 % ee). This newly developed cascade process may be tailored and used for the biocatalytic production of various vitamin B5 derivatives by modifying the pantoyl or β‐alanine moiety.
Single‐Site, Organometallic Aluminum Catalysts for the Precise Group Transfer Polymerization of Michael‐Type Monomers
Authors: Weger Michael , Giuman Marco M. , Knaus Maximilian G. , Ackermann Maximilian , Drees Markus , Hornung Julius , Altmann Philipp J. , Fischer Roland A. , Rieger Bernhard 
Published: September 2018

AbstractInvited for the cover of this issue is the group of Bernhard Rieger and colleagues at the Technical University of Munich. The image depicts a polymerization process with an aluminum‐based catalyst and its cyclopentadienyl‐ligands. Read the full text of the article at 10.1002/chem.201802075.
Cobalt‐Based Metal–Organic Framework Nanoarrays as Bifunctional Oxygen Electrocatalysts for Rechargeable Zn‐Air Batteries
Authors: Chen Guangbo , Zhang Jian , Wang Faxing , Wang Lanlan , Liao Zhongquan , Zschech Ehrenfried , Müllen Klaus , Feng Xinliang 
Published: September 2018

AbstractOwing to their high theoretical energy density, environmental benign character, and low cost, rechargeable Zn‐air batteries have emerged as an attractive energy technology. Unfortunately, their energy efficiency is seriously plagued by sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) that alternately occurs on air electrodes. Herein, we demonstrate Co‐based metal–organic framework (Co(bpdc)(H2O)4 (bpdc=biphenyl −4, 4′‐dicarboxylic acid), Co‐MOF) arrays as novel bifunctional oxygen electrocatalysts. The Co‐MOF is in situ constructed on a three‐dimensional graphite foam (GF) through a hydrothermal reaction. In a 1 m KOH aqueous solution, the resultant Co‐MOF/GF exhibits an OER overpotential of only ≈220 mV at 10 mA cm−2, which is much lower than those for Ir/C and previously reported noble metal‐free electrocatalysts. In conjunction with its ORR half‐wave potential of 0.7 V (vs. RHE), the Co‐MOF/GF manifests a greatly decreased potential gap of ≈0.75 V in comparison with Pt/C‐Ir/C couple and previously reported bifunctional oxygen electrocatalysts. Furthermore, an assembled rechargeable zinc‐air battery using Co‐MOF electrocatalyst in an air electrode delivers a maximum power density of 86.2 mW cm−2 and superior charge–discharge performance. Microscopic, spectroscopic and electrochemical analyses prove that the initial Co‐MOF is transformed into Co‐oxyhydroxides during the OER and ORR process, which essentially serve as bifunctional active centers.
Box‐Behnken response surface modeling assisted enantiomeric resolution of some racemic β‐blockers using HPTLC and β‐cyclodextrin as chiral mobile phase additive: Application to check the enantiomeric purity of betaxolol
Authors: El‐Kimary Eman I. , Ragab Marwa A.A. 
Published: September 2018

AbstractStereospecific separation method of (±) betaxolol, (±) carvedilol, and (±) sotalol using High Performance Thin Layer Chromatography (HPTLC) and β‐cyclodextrin as chiral selector has been developed and validated. The Box‐Behnken surface response design was selected for optimizing the operating variables based on 15 trials design. The optimized method involves separation on Fluka HPTLC silica gel plates 60 F254 (20 × 10 cm) using acetonitrile‐methanol‐acetic acid‐water (3.4:3.6:0.18:1 v/v) as a mobile phase containing 0.57 mM β‐cyclodextrin. Densitometric measurements were made at 220 nm for betaxolol and sotalol or at 245 nm for carvedilol. Maximum separation of the enantiomers of the three drugs was obtained by optimizing concentration of chiral selector, the mobile phase composition including acetonitrile amount in the organic part of the mobile phase and the volume of acetic acid added. The proposed method enables estimation of (−) and (+) enantiomers of betaxolol in drug substance and in various pharmaceuticals. The detection limit of betaxolol was 0.15 and 0.13 μg band−1 for (−) and (+) enantiomers, respectively. The detection limits were found to be 0.2 and 0.3 μg band−1 for carvedilol and sotalol, respectively, as racemate. In addition, the proposed method was applied in checking the enantiomeric purity of (−) BET in the presence of (+) BET at 1% level where the inactive (+) enantiomer was quantified with good accuracy and precision at 1% level in the active (−) enantiomer.
Lithiumgewinnung aus heimischen Rohstoffen
Authors: Martin Gunther , Schneider Anke , Bertau Martin 
Published: September 2018

ZusammenfassungLithium gilt als eines der strategischen Elemente mit einem großen Zukunftspotential. Vor dem Hintergrund eines steigenden Bedarfs, aber auch der Ungleichverteilung der weltweiten Lithiumvorkommen gilt es, auch heimische Vorkommen wie die Zinnwalditlagerstätte bei Zinnwald/Cínovec (650.000 t Li), für eine mögliche großtechnische Lithiumgewinnung genauer zu betrachten. Unter Berücksichtigung der besonderen Voraussetzungen des lithiumhaltigen Minerals erfolgte die Entwicklung von zwei verschiedenen Verfahren zur Lithiumcarbonatgewinnung aus Zinnwalditkonzentrat. Dabei wurden sowohl ein ganzheitlicher Salzsäureaufschluss wie auch ein selektives Direktcarbonatisierungsverfahren mittels überkritischem Kohlendioxid untersucht. Bei dem salzsäurebasierten Verfahren wird durch eine optimierte Laugung bis zu 96 % des im Zinnwalditkonzentrat enthaltenen Lithiums mobilisiert. Säurerückgewinnungsverfahren reduzieren dabei den Säurebedarf. Die Umsetzung von kalziniertem Zinnwalditkonzentrat (~ 950 °C) im System sc‐CO2/H2O ist ein vielversprechender Ansatz zur Lithiumcarbonatgewinnung (COOL‐Verfahren). Grundlage des Direktcarbonatisierungsverfahren ist das umfassende Verständnis der mineralischen Zusammensetzung sowie des thermischen Verhaltens in oxidierender Atmosphäre. Bei minimalem Chemikalieneinsatz werden durch den CO2‐Aufschluss hochselektiv Alkalimetallkationen, bevorzugt Lithium, als Hydrogencarbonate mobilisiert. Die aus ökonomischer Sicht zu bevorzugenden Aufschlussparameter (Doppellaugung, Fest : Flüssig‐Verhältnis ~ 1:30, 230 °C, 100 bar, 3 h, d50 ~ 18 μm) führten zu einer Lithiumlaugungsrate von 71 %.
Cationic Branched Polyethylenimine (BPEI) Disables Antibiotic Resistance in Methicillin‐Resistant Staphylococcus epidermidis (MRSE)
Authors: Lam Anh K. , Hill Melissa A. , Moen Erika L. , Pusavat Jennifer , Wouters Cassandra L. , Rice Charles V. 
Published: September 2018

AbstractStaphylococcus epidermidis is one of the most prevalent prokaryotic species on human skin and mucosal membranes that constitute the commensal flora. S. epidermidis has become one of the most common causes of primary bacteremia. Infections are difficult to diagnose because the pathogen has natural niches on human skin and the ability to adhere to inanimate surfaces via biofilms. Alarmingly, S. epidermidis has acquired resistance to many antibiotics, which presents a danger to human health. Known as methicillin‐resistant S. epidermidis (MRSE), most clinical isolates of MRSE in North America exhibit β‐lactam resistance primarily due to the presence of mecA, a gene that bestows β‐lactam antibiotic resistance in a manner similar to methicillin‐resistant Staphylococcus aureus (MRSA). MecA encodes for expression of penicillin‐binding protein 2a (PBP2a), which is absent in β‐lactam susceptible strains of S. epidermidis. We can disable this resistance factor in MRSE with 600‐Da branched polyethylenimine (BPEI). Cationic BPEI targets anionic wall teichoic acid (WTA), an essential cofactor for proper functioning of PBP2a. We found that BPEI synergizes the activity of β‐lactam antibiotics against MRSE. Growth curves suggest that the combination of BPEI and oxacillin is bactericidal. Electron micrographs indicate abnormalities in the cellular septa and cell walls of treated samples. Therefore, first‐line clinical treatments can be effective against MRSE when used in combination with BPEI.