bluuebunny/crossref_metadata_2025_split huggingface dataset:
Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 2: Insights from Oligocene–Miocene dinoflagellate cyst assemblages
Authors: Bijl Peter K. , Houben Alexander J. P. , Hartman Julian D. , Pross Jörg , Salabarnada Ariadna , Escutia Carlota , Sangiorgi Francesca 
Published: July 2018

Abstract. Next to atmospheric CO2 concentrations, ice-proximal oceanographic
conditions are a critical factor for the stability of Antarctic
marine-terminating ice sheets. The Oligocene and Miocene epochs
(∼ 34–5 Myr ago) were time intervals with atmospheric CO2
concentrations between those of present-day and those expected for the near
future. As such, these past analogues may provide insights into ice-sheet
volume stability under warmer-than-present-day climates. We present
organic-walled dinoflagellate cyst (dinocyst) assemblages from
chronostratigraphically well-constrained Oligocene to mid-Miocene sediments
from Integrated Ocean Drilling Program (IODP) Site U1356. Situated
offshore the Wilkes Land continental margin, East Antarctica, the sediments
from Site U1356 have archived the dynamics of an ice sheet that is today
mostly grounded below sea level. We interpret dinocyst assemblages in terms
of paleoceanographic change on different timescales, i.e. with regard to
both glacial–interglacial and long-term variability. Our record shows that a
sea-ice-related dinocyst species, Selenopemphix antarctica, occurs
only for the first 1.5 Myr of the early Oligocene, following the onset of full
continental glaciation on Antarctica, and after the Mid-Miocene Climatic
Optimum. Dinocysts suggest a weaker-than-modern sea-ice season for the
remainder of the Oligocene and Miocene. The assemblages generally bear strong
similarity to present-day open-ocean, high-nutrient settings north of the
sea-ice edge, with episodic dominance of temperate species similar to those
found in the present-day subtropical front. Oligotrophic and temperate
surface waters prevailed over the site notably during interglacial times,
suggesting that the positions of the (subpolar) oceanic frontal systems have
varied in concordance with Oligocene–Miocene glacial–interglacial climate
variability.
Piezo‐Phototronic Effect for Enhanced Flexible MoS2/WSe2 van der Waals Photodiodes
Authors: Lin Pei , Zhu Laipan , Li Ding , Xu Liang , Pan Caofeng , Wang Zhonglin 
Published: July 2018

AbstractThe recent discoveries of transition‐metal dichalcogenides (TMDs) as novel 2D electronic materials hold great promise to a rich variety of artificial van der Waals (vdWs) heterojunctions and superlattices. Moreover, most of the monolayer TMDs become intrinsically piezoelectric due to the lack of structural centrosymmetry, which offers them a new degree of freedom to interact with external mechanical stimuli. Here, fabrication of flexible vdWs p–n diode by vertically stacking monolayer n‐MoS2 and a few‐layer p‐WSe2 is achieved. Electrical measurement of the junction reveals excellent current rectification behavior with an ideality factor of 1.68 and photovoltaic response is realized. Performance modulation of the photodiode via piezo‐phototronic effect is also demonstrated. The optimized photoresponsivity increases by 86% when introducing a −0.62% compressive strain along MoS2 armchair direction, which originates from realigned energy‐band profile at MoS2/WSe2 interface under strain‐induced piezoelectric polarization charges. This new coupling mode among piezoelectricity, semiconducting, and optical properties in 2D materials provides a new route to strain‐tunable vdWs heterojunctions and may enable the development of novel ultrathin optoelectronics.
Composition‐Tuned Wide Bandgap Perovskites: From Grain Engineering to Stability and Performance Improvement
Authors: Zhou Yang , Jia Yong‐Heng , Fang Hong‐Hua , Loi Maria Antonietta , Xie Fang‐Yan , Gong Li , Qin Min‐Chao , Lu Xin‐Hui , Wong Ching‐Ping , Zhao Ni 
Published: July 2018

AbstractWide bandgap (WB) organic–inorganic hybrid perovskites (OIHPs) with a bandgap ranging between 1.7 and 2.0 eV have shown great potential to improve the efficiency of single‐junction silicon or thin‐film solar cells by forming a tandem structure with one of these cells or with a narrow bandgap perovskite cell. However, WB‐OIHPs suffer from a large open‐circuit voltage (Voc) deficit in photovoltaic devices, which is associated with the phase segregation of the materials under light illumination. In this work the photoinstability is demonstrated and Voc loss can be addressed by combining grain crystallization and grain boundary passivation, achieved simultaneously through tuning of perovskite precursor composition. Using FA0.17Cs0.83PbI3–xBrx (x = 0.8, 1.2 1.5, and 1.8), with a varied bandgap from 1.72 to 1.93 eV, as the model system it is illustrated how precursor additive Pb(SCN)2 should be matched with a proper ratio of FAX (I and Br) to realize large grains with defect‐healed grain boundaries. The optimized WB‐OIHPs show good photostability at both room‐temperature and elevated temperature. Moreover, the corresponding solar cells exhibit excellent photovoltaic performances with the champion Voc/stabilized power output efficiency reaching 1.244 V/18.60%, 1.284 V/16.51%, 1.296 V/15.01%, and 1.312 V/14.35% for WB‐OIHPs with x = 0.8, 1.2, 1.5, and 1.8, respectively.
The Application of Hollow Structured Anodes for Sodium‐Ion Batteries: From Simple to Complex Systems
Authors: Xie Fangxi , Zhang Lei , Ye Chao , Jaroniec Mietek , Qiao Shi‐Zhang 
Published: July 2018

AbstractHollow structures exhibit fascinating and important properties for energy‐related applications, such as lithium‐ion batteries, supercapacitors, and electrocatalysts. Sodium‐ion batteries, as analogs of lithium‐ion batteries, are considered as promising devices for large‐scale electrical energy storage. Inspired by applications of hollow structures as anodes for lithium‐ion batteries, the application of these structures in sodium‐ion batteries has attracted great attention in recent years. However, due to the difference in lithium and sodium‐ion batteries, there are several issues that need to be addressed toward rational design of hollow structured sodium anodes. Herein, this research news article presents the recent developments in the synthesis of hollow structured anodes for sodium‐ion batteries. The main strategies for rational design of materials for sodium‐ion batteries are presented to provide an overview and perspectives for the future developments of this research area.
Designing Efficient Energy Funneling Kinetics in Ruddlesden–Popper Perovskites for High‐Performance Light‐Emitting Diodes
Authors: Yantara Natalia , Bruno Annalisa , Iqbal Azhar , Jamaludin Nur Fadilah , Soci Cesare , Mhaisalkar Subodh , Mathews Nripan 
Published: July 2018

AbstractMixed Ruddlesden–Popper (RP) perovskites are of great interest in light‐emitting diodes (LEDs), due to the efficient energy transfer (funneling) from high‐bandgap (donor) domains to low‐bandgap (acceptor) domains, which leads to enhanced photoluminescence (PL) intensity, long PL lifetime, and high‐efficiency LEDs. However, the influence of reduced effective emitter centers in the active emissive film, as well as the implications of electrical injection into the larger bandgap donor material, have not been addressed in the context of an active device. The electrical and optical signatures of the energy cascading mechanisms are critically assessed and modulated in a model RP perovskite series ((C8H17NH3)2(CH(NH2)2)m−1PbmBr3m+1). Optimized devices demonstrate a current efficiency of 22.9 cd A−1 and 5% external quantum efficiency, more than five times higher than systems where funneling is absent. The signature of nonideal funneling in RP perovskites is revealed by the appearance of donor electroluminescence from the device, followed by a reduction in the LED performance
Interface Engineering for All‐Inorganic CsPbI2Br Perovskite Solar Cells with Efficiency over 14%
Authors: Yan Lei , Xue Qifan , Liu Meiyue , Zhu Zonglong , Tian Jingjing , Li Zhenchao , Chen Zhen , Chen Ziming , Yan He , Yip Hin‐Lap , Cao Yong 
Published: July 2018

AbstractIn this work, a SnO2/ZnO bilayered electron transporting layer (ETL) aimed to achieve low energy loss and large open‐circuit voltage (Voc) for high‐efficiency all‐inorganic CsPbI2Br perovskite solar cells (PVSCs) is introduced. The high‐quality CsPbI2Br film with regular crystal grains and full coverage can be realized on the SnO2/ZnO surface. The higher‐lying conduction band minimum of ZnO facilitates desirable cascade energy level alignment between the perovskite and SnO2/ZnO bilayered ETL with superior electron extraction capability, resulting in a suppressed interfacial trap‐assisted recombination with lower charge recombination rate and greater charge extraction efficiency. The as‐optimized all‐inorganic PVSC delivers a high Voc of 1.23 V and power conversion efficiency (PCE) of 14.6%, which is one of the best efficiencies reported for the Cs‐based all‐inorganic PVSCs to date. More importantly, decent thermal stability with only 20% PCE loss is demonstrated for the SnO2/ZnO‐based CsPbI2Br PVSCs after being heated at 85 °C for 300 h. These findings provide important interface design insights that will be crucial to further improve the efficiency of all‐inorganic PVSCs in the future.
Dotted Core–Shell Nanoparticles for T1‐Weighted MRI of Tumors
Authors: Shen Zheyu , Song Jibin , Zhou Zijian , Yung Bryant C. , Aronova Maria A. , Li Yan , Dai Yunlu , Fan Wenpei , Liu Yijing , Li Zihou , Ruan Huimin , Leapman Richard D. , Lin Lisen , Niu Gang , Chen Xiaoyuan , Wu Aiguo 
Published: July 2018

AbstractGd‐based T
1‐weighted contrast agents have dominated the magnetic resonance imaging (MRI) contrast agent market for decades. Nevertheless, they are reported to be nephrotoxic and the U.S. Food and Drug Administration has issued a general warning concerning their use. In order to reduce the risk of nephrotoxicity, the MRI performance of the Gd‐based T
1‐weighted contrast agents needs to be improved to allow a much lower dosage. In this study, novel dotted core–shell nanoparticles (FeGd‐HN3‐RGD2) with superhigh r
1 value (70.0 mM−1 s−1) and very low r
2/r
1 ratio (1.98) are developed for high‐contrast T
1‐weighted MRI of tumors. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay and histological analyses show good biocompatibility of FeGd‐HN3‐RGD2. Laser scanning confocal microscopy images and flow cytometry demonstrate active targeting to integrin αvβ3 positive tumors. MRI of tumors shows high tumor ΔSNR for FeGd‐HN3‐RGD2 (477 ± 44%), which is about 6‐7‐fold higher than that of Magnevist (75 ± 11%). MRI and inductively coupled plasma results further confirm that the accumulation of FeGd‐HN3‐RGD2 in tumors is higher than liver and spleen due to the RGD2 targeting and small hydrodynamic particle size (8.5 nm), and FeGd‐HN3‐RGD2 is readily cleared from the body by renal excretion.
Nasal airflow resistance measured by rhinomanometry in a healthy population of China
Authors: Ren Lei , Zhang Luo , Duan Su , Zhang Wei , Zhang Yuan 
Published: July 2018

BackgroundAlthough nasal congestion is among the most common symptoms in subjects suffering from nasal diseases, relatively few data on normal airflow resistance are available for reference, especially in healthy Chinese subjects. The aim of present study was therefore to objectively measure the normal airflow resistance by rhinomanometry, and calculate mean and standard reference intervals in a cohort of healthy Chinese subjects.MethodsA total of 1084 participants were recruited in Huairou region in Beijing, China from November to December 2011. All participants were required to complete 2 questionnaires and undergo nasal examination and objective assessment of nasal resistance by rhinomanometry and acoustic rhinometry.ResultsA total of 704 adults completed both questionnaires and nasal examinations; with 505 (71.73%) subjects considered “healthy” based on negative medical history, absence of nasal symptoms, and normal findings by nasal examination. The mean total nasal resistance in the congested nose was 0.168 Pa/cm3/sec (95% CI, 0.068 to 0.268 Pa/cm3/sec) at 75 Pa pressure and 0.243 Pa/cm3/sec (95% CI, 0.112 to 0.374 Pa/cm3/sec) at 150 Pa pressure. The mean total nasal resistance in males was significantly lower compared to females at 75 Pa and 150 Pa (p < 0.001). The mean unilateral nasal resistance was 0.357 Pa/cm3/sec (95% CI, 0.034 to 0.680 Pa/cm3/sec) at 75 Pa and 0.511 Pa/cm3/sec (95% CI, 0.086 to 0.936 Pa/cm3/sec) at 150 Pa, with no significant difference between males and females. Application of a vasoconstrictor decreased both total and unilateral nasal resistance, which was significant at 75 Pa.ConclusionThese reference values maybe useful for the Chinese clinicians in evaluating the nasal function and in choosing and assessing efficacy of therapy for nasal congestion in Chinese patients.
A Far‐Red Fluorescent DNA Binder for Interaction Studies of Live Multidrug‐Resistant Pathogens and Host Cells
Authors: Schulte Leon N. , Heinrich Benedikt , Janga Harshavardhan , Schmeck Bernd T. , Vázquez Olalla 
Published: July 2018

AbstractTransgene expression of green fluorescent protein (GFP) has facilitated the spatiotemporal investigation of host–pathogen interactions; however, introduction of the GFP gene remains challenging in drug‐resistant bacteria. Herein, we report a novel far‐red fluorescent nucleic acid stain, 6‐TramTO‐3, which efficiently labels bacteria through a DNA binding mode without affecting growth and viability. Exemplarily, we stained Klebsiella pneumoniae, a major threat to hospitalized patients, and deciphered divergent interaction strategies of antibiotic‐resistant and antibiotic‐sensitive Klebsiella strains with immune cells. 6‐TramTO‐3 constitutes an off‐the‐shelf reagent for real‐time analysis of bacterial infection, including strains for which the use of genetically encoded reporters is not feasible. Eventually, our approach may aid the development of strategies to combat a major worldwide health threat: multidrug‐resistant bacteria.
Control of the Stereochemical Course of [4+2] Cycloaddition during trans‐Decalin Formation by Fsa2‐Family Enzymes
Authors: Kato Naoki , Nogawa Toshihiko , Takita Ryo , Kinugasa Kiyomi , Kanai Misae , Uchiyama Masanobu , Osada Hiroyuki , Takahashi Shunji 
Published: July 2018

AbstractEnzyme‐catalyzed [4+2] cycloaddition has been proposed to be a key transformation process in various natural product biosynthetic pathways. Recently Fsa2 was found to be involved in stereospecific trans‐decalin formation during the biosynthesis of equisetin, a potent HIV‐1 integrase inhibitor. To understand the mechanisms by which fsa2 determines the stereochemistry of reaction products, we sought an fsa2 homologue that is involved in trans‐decalin formation in the biosynthetic pathway of an enantiomerically opposite analogue, and we found phm7, which is involved in the biosynthesis of phomasetin. A decalin skeleton with an unnatural configuration was successfully constructed by gene replacement of phm7 with fsa2, thus demonstrating enzymatic control of all stereochemistry in the [4+2] cycloaddition. Our findings highlight enzyme‐catalyzed [4+2] cycloaddition as a stereochemically divergent step in natural product biosynthetic pathways and open new avenues for generating derivatives with different stereochemistry.
Bis(η5:η1‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives
Authors: Manßen Manfred , Dierks Anna , de Graaff Simon , Schmidtmann Marc , Beckhaus Rüdiger 
Published: July 2018

AbstractTransition‐metal carbene complexes and their reactivities are a key topic of chemistry. They are an integral part of researches in catalysis, organic synthesis, coordination chemistry, and numerous other areas. In this context, we report the synthesis of a low‐valent bis(η5:η1‐(di‐p‐tolyl)‐pentafulvene)niobium chloride. Owing to the π‐η5:σ‐η1 coordination mode of the pentafulvenes and the resulting high nucleophilic character of the exocyclic carbon atom of the ligand, the bis(η5:η1‐pentafulvene)niobium complex is able to achieve the umpolung of a coordinated vinyl unit and the resulting formation of the first η5:η1 cyclic niobium Schrock carbene complex. This new synthetic route is, in comparison to classical α‐hydrogen elimination reactions or thermolysis of diazo compounds, completely unprecedented. The reactivity of the cyclic carbene function and the remaining fulvene ligand is demonstrated by double N−H bond activation of primary amines to niobium imido complexes.
Bor(II)‐Kationen: Ein Zusammenspiel zwischen Lewis‐Paar‐Akzeptor‐ und Elektronendonor‐Eigenschaften
Authors: Widera Anna , Vogler Daniel , Wadepohl Hubert , Kaifer Elisabeth , Himmel Hans‐Jörg 
Published: July 2018

AbstractBor(III)‐Kationen finden in der Synthesechemie eine breite Anwendung als Lewis‐Säuren. Im Gegensatz dazu sind Bor(II)‐Kationen ausgesprochen selten, und ihre Chemie ist nahezu unerforscht. Sie sind zugleich Lewis‐Säuren und Elektronendonoren, Eigenschaften, die gewöhnlich mit katalytisch aktiven Metallkomplexen der späten Übergangsmetallreihe assoziiert werden. Dieses zweifache Reaktivitätsmuster lässt eine reiche und vielfältige Chemie erwarten. Hier berichten wir über eine einfache Synthese einiger neuer Bor(II)‐Kationen beginnend mit einem besonderen Diboran mit zwei leicht austauschbaren Triflatsubstituenten. Durch die Erhöhung der π‐Akzeptorstärke neutraler σ‐Donoren als Reaktionspartner konnte zum ersten Mal die kombinierte Lewis‐Acidität und Elektronendonor‐Eigenschaft der Bor(II)‐Kationen zur Reduktion organischer Moleküle angewendet werden. Die Ergebnisse unserer Untersuchung bahnen den Weg zur Anwendung dieser ungewöhnlichen Verbindungen in der Synthesechemie.
Selection of Secondary Structures of Heterotypic Supramolecular Peptide Assemblies by an Enzymatic Reaction
Authors: Li Jie , Zhan Ziqing , Du Xuewen , Wang Jiaqing , Hong Brandon , Xu Bing 
Published: July 2018

AbstractIn a model study to investigate the consequence of reactions of intrinsically disordered regions (IDRs) of proteins in the context of the formation of highly ordered structures, we found that enzymatic reactions control the secondary structures of peptides during assembly. Specifically, phosphorylation of an α‐helix‐dominant peptide results in mostly disordered conformations, which become β‐strand‐dominant after enzymatic dephosphorylation to regenerate the peptide. In the presence of another peptide largely with a β‐strand conformation, direct coassembly of the peptides results in amorphous aggregates consisting of α‐helix and β‐strand peptides, but the enzymatically generated peptide coassemblies (from the phosphopeptide) mainly adopt a β‐strand conformation and form ordered structures (e.g., nanofibers). These results indicate that enzymatic dephosphorylation instructs conformationally flexible peptides to adopt thermodynamically favorable conformations in homotypic or heterotypic supramolecular assemblies.
A three‐dimensional (3D) manganese (II) coordination polymer: Synthesis, structure and catalytic activities
Authors: Pal Souvik , Maiti Sudip , Nayek Hari Pada 
Published: July 2018

A new Mn (II)‐containing coordination polymer, [Mn6(Ipa)6(ad)⋅6H2O] (1; Ipa = isophthalate ligand; ad = adenine), was synthesized by reacting hydrated manganese nitrate with isophthalic acid and adenine under solvothermal reaction conditions. Polymer 1 was characterized using single‐crystal X‐ray diffraction analysis and other techniques such as Fourier transform infrared spectroscopy, elemental analyses and powder X‐ray diffraction. The solid‐state structure of 1 confirmed the formation of a three‐dimensional framework structure based on Mn6 secondary building units. Phase purity of bulk 1 and its thermal stability were investigated. Polymer 1 was evaluated for its performance as a heterogeneous catalyst for the Henry (nitroaldol) reaction of nitromethane with several aldehydes. The recyclability of 1 and heterogeneity of the reaction were also explored. A plausible mechanism for such reaction is proposed. To the best of our knowledge, polymer 1 represents the first example of a Mn (II)‐ and adenine‐containing coordination polymer as well as the first example of a Mn (II)‐containing coordination polymer that has been employed for the Henry reaction.
Iron oxide modified with pyridyl‐triazole ligand for stabilization of gold nanoparticles: An efficient heterogeneous catalyst for A3 coupling reaction in water
Authors: Gholinejad Mohammad , Zareh Fatemeh , Najera Carmen 
Published: July 2018

Fe3O4 nanoparticles were modified with pyridyl‐triazole ligand and the new magnetic solid was applied for the stabilization of very small and uniform gold nanoparticles. The resulting magnetic material, Fe3O4@PT@Au, was characterized using various methods. These gold nanoparticles on a magnetic support were applied as an efficient heterogeneous catalyst for the three‐component reaction of amines, aldehydes and alkynes (A3 coupling) in neat water with 0.01 mol% Au loading. Using magnetic separation, this catalyst could be recycled for seven consecutive runs with very small decrease in activity. Characterization of the reused catalyst did not show appreciable structural modification.
DFT/TDDFT insight into the impact of ring size of the NHC chelating unit of high effective phosphorescent Platinum (II) complexes
Authors: Yan Xi , Li Wenqian , Zhang Huize , Cai Wanlin , Wang Jian , Shen Wei 
Published: July 2018

Uncovering the photodeactivation mechanisms of unique N‐heterocyclic carbene (NHC)‐based transition metal complexes is favorable for designing more high‐efficiency phosphorescent materials. In this work, four bidentate platinum (II) complexes with NHC‐chelate are investigated by the density functional theory (DFT) and time‐dependent density functional theory (TDDFT) to probe into how the ring size of NHC‐chelate unit influences on electronic structures and the phosphorescent properties. To illustrate the photodeactivation mechanisms clearly, three significant photodeactivation processes (radiative decay process, temperature‐independent and temperature‐dependent nonradiative decay processes) were taken into consideration. We stated that radiative decay rate constants kr slightly increased with declined number of NHC‐chelate ring, owing to the gradually larger SOC matrix elements between the T1 state and Sn states. Combining the temperature‐independent with temperature‐dependent nonradiative decay processes, the nonradiative decay rate knr is Pt‐4 (five‐membered) < Pt‐3 (six‐membered) < Pt‐2 (seven‐membered) < Pt‐1 (eight‐membered). The calculated results testify that the decrease of size of the NHC chelating unit is a reliable insurance to improve the quantum yield. The designed complex Pt‐4 with five‐membered NHC‐ring can serve as a highly efficient phosphorescent material in the future. The results indicated controlling the ring size of NHC‐chelate is a feasible method to tune phosphorescence properties of Pt (II) complexes.