bluuebunny/crossref_metadata_2025_split huggingface dataset:
Iridium(III)‐Catalyzed Intermolecular C(sp3)−H Insertion Reaction of Quinoid Carbene: A Radical Mechanism
Authors: Wang Hai‐Xu , Richard Yann , Wan Qingyun , Zhou Cong‐Ying , Che Chi‐Ming 
Published: November 2019

AbstractDescribed herein is an IrIII/porphyrin‐catalyzed intermolecular C(sp3)−H insertion reaction of a quinoid carbene (QC). The reaction was designed by harnessing the hydrogen‐atom transfer (HAT) reactivity of a metal‐QC species with aliphatic substrates followed by a radical rebound process to afford C−H arylation products. This methodology is efficient for the arylation of activated hydrocarbons such as 1,4‐cyclohexadienes (down to 40 min reaction time, up to 99 % yield, up to 1.0 g scale). It features unique regioselectivity, which is mainly governed by steric effects, as the insertion into primary C−H bonds is favored over secondary and/or tertiary C−H bonds in the substituted cyclohexene substrates. Mechanistic studies revealed a radical mechanism for the reaction.
Model‐Based Nanoengineered Pharmacokinetics of Iron‐Doped Copper Oxide for Nanomedical Applications
Authors: Naatz Hendrik , Manshian Bella B. , Rios Luci Carla , Tsikourkitoudi Vasiliki , Deligiannakis Yiannis , Birkenstock Johannes , Pokhrel Suman , Mädler Lutz , Soenen Stefaan J. 
Published: November 2019

AbstractThe progress in nanomedicine (NM) using nanoparticles (NPs) is mainly based on drug carriers for the delivery of classical chemotherapeutics. As low NM delivery rates limit therapeutic efficacy, an entirely different approach was investigated. A homologous series of engineered CuO NPs was designed for dual purposes (carrier and drug) with a direct chemical composition–biological functionality relationship. Model‐based dissolution kinetics of CuO NPs in the cellular interior at post‐exposure conditions were controlled through Fe‐doping for intra/extra cellular Cu2+ and biological outcome. Through controlled ion release and reactions taking place in the cellular interior, tumors could be treated selectively, in vitro and in vivo. Locally administered NPs enabled tumor cells apoptosis and stimulated systemic anti‐cancer immune responses. We clearly show therapeutic effects without tumor cells relapse post‐treatment with 6 % Fe‐doped CuO NPs combined with myeloid‐derived suppressor cell silencing.
An Organic–Inorganic Hybrid Cathode Based on S–Se Dynamic Covalent Bonds
Authors: Zhao Jiawei , Si Yubing , Han Zixiao , Li Junjie , Guo Wei , Fu Yongzhu 
Published: November 2019

AbstractA diphenyl trisulfide–selenium nanowire (DPTS‐Se) organic–inorganic hybrid cathode material is presented for rechargeable lithium batteries. During discharge, three voltage plateaus associated with three lithiation processes are observed. During recharge, the combination of the radicals formed upon delithiation leads to several new phenyl sulfoselenide compounds which are confirmed by HPLC‐QTof‐MS. The hybrid cathode exhibits superior cycling stability over pristine Se or DPTS as cathode alone. The first discharge shows a capacity of 96.5 % of the theoretical specific capacity and the cell retains 69.2 % of the initial capacity over 250 cycles. The hybrid cathode also shows a high Coulombic efficiency of over 99 % after 250 cycles. This study demonstrates that the combination of organic polysulfide and selenium can not only improve the utilization of active materials but also enhance the cycling performance.
Nickel‐Catalyzed Asymmetric Reductive 1,2‐Carboamination of Unactivated Alkenes
Authors: He Jun , Xue Yuhang , Han Bo , Zhang Chunzhu , Wang You , Zhu Shaolin 
Published: November 2019

AbstractStarting from diverse alkene‐tethered aryl iodides and O‐benzoyl‐hydroxylamines, the enantioselective reductive cross‐electrophilic 1,2‐carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β‐chiral amines with an enantioenriched aryl‐substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis.
Enantioselective Difunctionalization of Alkenes by a Palladium‐Catalyzed Heck/Sonogashira Sequence
Authors: Zhou Lujia , Li Sanliang , Xu Bing , Ji Danting , Wu Lizuo , Liu Yu , Zhang Zhan‐Ming , Zhang Junliang 
Published: November 2019

AbstractSonogashira‐type cross‐couplings are one of the most significant alkynylations in organic chemistry. One of the first palladium‐catalyzed intramolecular Heck/Sonogashira reactions of alkenes with terminal alkynes is now reported. With this method, a variety of uniquely substituted chiral benzene‐fused heterocycles bearing a propargyl‐substituted all‐carbon quaternary stereocenter were obtained in a straightforward, high‐yielding, and highly stereoselective manner under mild conditions. Salient features of this process include the use of readily available substrates, high selectivities, a broad substrate scope as well as versatile product functionalizations.
Synthesis of nonplanar bipyridyls bridged by disilane and disiloxane and their phosphorescent copper complexes
Authors: Ohshita Joji , Kai Takashi , Adachi Yohei , Yamaji Kosuke , Nakamura Masashi , Watase Seiji , Mori Shingo , Matsuyama Noritsumi 
Published: November 2019

Disilane‐ and disiloxane‐bridged bipyridyls (DSBPy and DSOBPy) were prepared and their optical properties were investigated in comparison with those of previously reported monosilane‐ and monogermane‐bridged counterparts. The UV–visible absorption and photoluminescence bands of DSBPy and DSOBPy were blue‐shifted as a result of elongation of the bridging units from monosilane and monogermane to disilane and disiloxane, likely due to the enhanced twisting of the bipyridyl units. Phosphorescent complexes DSBPy–Cu and DSOBPy–Cu were prepared by the interaction of DSBPy and DSOBPy with Cu2I2(PPh3)2. X‐ray diffraction studies of their single‐crystal structures revealed polymeric structures composed of repeat units of DSBPy or DSOBPy and [CuII(PPh3)]2. Organic light‐emitting diodes with the ITO/PEDOT:PSS/DSBPy–Cu or DSOBPy–Cu:PCTSQ/TAZ/Al structure were fabricated to examine the applications of the complexes as electroluminescent materials. The devices emitted yellow light with emission maxima at approximately 600 nm, and maximal luminance reached 120 and 190 cd m−2 for devices based on DSBPy–Cu and DSOBPy–Cu, respectively. The performance of the DSOBPy–Cu‐based device was improved by using TAZ as the dopant of the emissive layer, and luminance was increased to 390 cd m−2.
Assessing the effectiveness of restoration actions for Bryozoans: The case of the Mediterranean Pentapora fascialis
Authors: Pagès‐Escolà Marta , Linares Cristina , Gómez‐Gras Daniel , Medrano Alba , Hereu Bernat 
Published: November 2019

Abstract

Marine ecosystems are highly affected by several human stressors. In this context, beyond passive restoration measures such as the creation of marine protected areas, it is urgent that we explore active restoration measures to enhance and accelerate the recovery of sessile marine species.
Bryozoans are among the most common sessile invertebrates in rocky bottom ecosystems and are considered habitat‐forming species that are highly vulnerable to physical disturbances, such as recreational diving, ghost fishing nets, and global warming, which makes them highly vulnerable to other impacts. Despite their ecological importance and vulnerability, to date restoration actions for bryozoans have rarely been explored.
In this study, different restoration techniques were developed and tested, with a focus on two types of effective methodologies previously applied to other marine invertebrates: recruitment enhancement and the transplantation of adult colonies, in both cases using the Mediterranean bryozoan Pentapora fascialis as a model species.
First, different types of artificial surfaces were installed in different coralligenous habitats to test the enhancement of recruitment, concluding that plastic grids are the best substrate in terms of facilitating the recruitment of new bryozoan colonies.
Second, different methodologies were tested for adult transplantation. The most successful was to fix colonies to a suitable substrate with a nylon thread attached to the colony ex situ (i.e. on the boat).
Using this technique a trial restoration programme was undertaken, involving transplanting adult colonies collected from a ghost fishing net trapped on the bottom, which showed a high survival rate of ~50% after 6 months.
The low economic cost of the implementation of the proposed techniques as well as the successful results obtained highlight the viability of restoring bryozoan populations over long temporal and spatial scales.
Filter‐based portfolio strategies in an HMM setting with varying correlation parametrizations
Authors: Erlwein‐Sayer Christina , Grimm Stefanie , Ruckdeschel Peter , Sass Jörn , Sayer Tilman 
Published: November 2019

AbstractWe consider portfolio optimization in a regime‐switching market. The assets of the portfolio are modeled through a hidden Markov model (HMM) in discrete time, where drift and volatility of the single assets are allowed to switch between different states. We consider different parametrizations of the involved asset covariances: statewise uncorrelated assets (though linked through the common Markov chain), assets correlated in a state‐independent way, and assets where the correlation varies from state to state. As a benchmark, we also consider a model without regime switches. We utilize a filter‐based expectation‐maximization (EM) algorithm to obtain optimal parameter estimates within this multivariate HMM and present parameter estimators in all three HMM settings. We discuss the impact of these different models on the performance of several portfolio strategies. Our findings show that for simulated returns, our strategies in many settings outperform naïve investment strategies, like the equal weights strategy. Information criteria can be used to detect the best model for estimation as well as for portfolio optimization. A second study using real data confirms these findings.
Determination of urinary methylhippuric acids using MIL‐53‐NH2 (Al) metal–organic framework in microextraction by packed sorbent followed by HPLC–UV analysis
Authors: Pirmohammadi Zahra , Bahrami Abdulrahman , Nematollahi Davood , Alizadeh Saber , Ghorbani Shahna Farshid , Rahimpoor Razzagh 
Published: November 2019

AbstractFor the analysis of methylhippuric acids (MHAs) in human urine samples, in this study, a new method based on the metal–organic framework (MOF) of MIL‐53‐NH2 (Al) in microextraction by packed sorbent (MEPS) was developed. The synthesis of MIL‐53‐NH2 (Al) was characterized by Fourier transform infrared spectra, field emission‐scanning electron microscopy and X‐ray diffraction. Response surface methodology was used to investigate the influences of several parameters including type and volume of elution, type of conditional solvent, sample volume and extraction cycle on MEPS efficiency. The results showed good recoveries (>94%) and excellent extraction efficiencies (>96%) at three different concentrations of 50, 500 and 1500 μg ml−1 (as low, mid and high concentrations, respectively) of MHA isomers. Calibration curves of MHAs were linear over the concentration range of 1–1500 μg ml−1, with high correlation coefficients (r ≥ 0.998). The reproducibility of the proposed MIL‐53‐MEPS for determination of three isomers of MHA was found to be in the range of 3.5–11.1%. After optimization of the proposed technique, it was used to analyze MHAs in urine samples of workers exposed to xylenes in a petrochemical plant in Asalouyah, Iran. The results indicated that the MOF–MEPS method was selective, sensitive, rapid and efficient for the extraction of urinary MHAs. The technique is also environmentally friendly and inexpensive, and the MOF sorbent is reusable.
How can ‘we’ help? Exploring the role of shared social identity in the experiences and benefits of volunteering
Authors: Gray Debra , Stevenson Clifford 
Published: November 2019

AbstractPrevious research on volunteering has largely focused on the individual characteristics and experiences of volunteers, or on their relationship with a volunteering organisation, neglecting the group dynamics of volunteering. To address this gap, we apply a social identity and “Social Cure” perspective in a thematic analysis of interviews with 40 volunteers from across the South of England. This analysis highlights that group identities are fundamental to volunteers' motivations and experiences of volunteering. Sharing an identity with other volunteers promoted feelings of belonging, which in turn impacted upon the participants' wellbeing. Identity processes also underpinned interactions with the beneficiaries of help and how volunteers managed the challenges of helping. Finally, shared identity facilitated collective support between volunteers, which was necessary to deal with the challenges of the volunteering role, and this could be facilitated or hindered by the volunteering organisation. We discuss the implications for how volunteering organisations can enhance identity‐mediated helping, as well as for understanding the impact of volunteering on health and wellbeing.
Rectal perforation after barium enema: A case report
Authors: Duarte Josiana de Oliveira Martins , Pereira Paula Maria Lobato Pestana , Sobral Ana Sofia Gonçalves , de Oliveira João Pedro Rosa , Rita Henrique José Barrelas , de Sousa e Costa José António 
Published: November 2019

AbstractColorectal perforation after barium enema it is a rare complication, but has a high mortality rate. With the emergence of endoscopic examinations, barium enemas have fallen into disuse and doctors are less aware of its complications. This case is of the utmost importance as failure to recognize it could be fatal.
Methylerythritol Phosphate Pathway: Enzymatic Evidence for a Rotation in the LytB/IspH‐Catalyzed Reaction
Authors: Chaignon Philippe , Petit Benoît Eric , Vincent Bruno , Allouche Lionel , Seemann Myriam 
Published: November 2019

AbstractIspH/LytB, an oxygen‐sensitive [4Fe‐4S] enzyme, catalyzes the last step of the methylerythritol phosphate (MEP) pathway, a target for the development of new antimicrobial agents. This metalloenzyme converts (E)‐4‐hydroxy‐3‐methylbut‐2‐en‐1‐yl diphosphate (HMBPP) into the two isoprenoid precursors: isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Here, the synthesis of (S)‐[4‐2H1]HMBPP and (R)‐[4‐2H1]HMBPP is reported together with a detailed NMR analysis of the products formed after their respective incubation with E. coli IspH/LytB in the presence of the biological reduction system used by E. coli to reduce the [4Fe‐4S] center. (S)‐[4‐2H1]HMBPP was converted into [4‐2H1]DMAPP and (E)‐[4‐2H1]IPP, whereas (R)‐[4‐2H1]HMBPP yielded [4‐2H1]DMAPP and (Z)‐[4‐2H1]IPP, hence providing the direct enzymatic evidence that the mechanism catalyzed by IspH/LytB involves a rotation of the CH2OH group of the substrate to display it away from the [4Fe‐4S].
Black Phosphorus Nanosheets Counteract Bacteria without Causing Antibiotic Resistance
Authors: Liu Wenxin , Zhang Yinan , Zhang Yanling , Dong Alideertu 
Published: November 2019

AbstractAntibiotic resistance poses severe health threats throughout the world. Exploring new antibiotics is widely recognized as an effective strategy to counter antibiotic resistance, but new antibiotics will eventually lead to further antibiotic resistance when new drugs are misused or overused. An alternative tactic may be antibacterial regulation on demand. Here, we show experimentally and theoretically that unstable black phosphorus nanosheets (BPNs) can function as antibacterial agents without causing antibiotic resistance. This antibacterial strategy relies on an unprecedented synergism: The BPNs use reactive oxygen species, are not toxic towards nonbacterial cells within a wide range of BPN concentration (0.01–2.0 mg mL−1), and are chemically degradable on demand. BPNs thus offer a promising approach to fighting bacterial infections without causing antibiotic resistance. We believe this proposed strategy offers new insights into instability‐guided antibacterial therapy in clinical applications and indicates a new direction for fighting antibiotic resistance.
Disappearing Polymorphs in Metal–Organic Framework Chemistry: Unexpected Stabilization of a Layered Polymorph over an Interpenetrated Three‐Dimensional Structure in Mercury Imidazolate
Authors: Speight Isaiah R. , Huskić Igor , Arhangelskis Mihails , Titi Hatem M. , Stein Robin S. , Hanusa Timothy P. , Friščić Tomislav 
Published: November 2019

AbstractThe “disappearing polymorph” phenomenon is well established in organic solids, and has had a profound effect in pharmaceutical materials science. The first example of this effect in metal‐containing systems in general, and in coordination‐network solids in particular, is here reported. Specifically, attempts to mechanochemically synthesize a known interpenetrated diamondoid (dia) mercury(II) imidazolate metal–organic framework (MOF) yielded a novel, more stable polymorph based on square‐grid (sql) layers. Simultaneously, the dia‐form was found to be highly elusive, observed only as a short‐lived intermediate in monitoring solvent‐free synthesis and not at all from solution. The destabilization of a dense dia‐framework relative to a lower dimensionality one is in contrast to the behavior of other imidazolate MOFs, with periodic density functional theory (DFT) calculations showing that it arises from weak interactions, including structure‐stabilizing agostic C−H⋅⋅⋅Hg contacts. While providing a new link between MOFs and crystal engineering of organic solids, these findings highlight a possible role for agostic interactions in directing topology and stability of MOF polymorphs.
Formation Mechanism of ZnO Nanorod Superstructures in Different Solvents
Authors: Yue Mingli , Yang Lei , Hou Ying , Zhu Jiaqi , Yang Ming 
Published: November 2019

AbstractHierarchical superstructures consisting of nanoscale building blocks show great potential in achieving configurable properties. In this work, two patterns of ZnO nanorod superstructures are obtained directly by thermal decomposition of zinc acetylacetonate in different solvents. Namely, fan‐shaped structures are obtained in methanol, whereas side‐by‐side assembly is achieved in n‐pentanol. Time‐dependent observations indicate the formation of quasi‐spherical particles at the beginning of the reaction, which later transform into different superstructures depending on the types of solvents. The selective formation of superstructures is rationalized based on the calculation of interaction potentials between two nanorods with either crossed or side‐by‐side spatial organizations. The results reveal the significant role of solvents in affecting electrostatic repulsion, which may compete with attractive van der Waals forces leading to the favored superstructures.
Effect of Water and Alkali‐Ion Content on the Structure of Manganese(II) Hexacyanoferrate(II) by a Joint Operando X‐ray Absorption Spectroscopy and Chemometric Approach
Authors: Mullaliu Angelo , Aquilanti Giuliana , Conti Paolo , Giorgetti Marco , Passerini Stefano 
Published: November 2019

AbstractManganese hexacyanoferrate (MnHCF) is made of earth‐abundant elements by a safe and easy synthesis. The material features a higher specific capacity at a higher potential than other Prussian blue analogs. However, the effect of hydration is critical to determine the electrochemical performance as both the electrochemical behavior and the reaction dynamics are affected by interstitial/structural water and adsorbed water. In this study, the electrochemical activity of MnHCF is investigated by varying the interstitial ion content through a joint operando X‐ray absorption spectroscopy and chemometric approach, with the intent to assess the structural and electronic modifications that occur during Na release and Li insertion, as well as the overall dynamic evolution of the system. In MnHCF, both the Fe and Mn centers are electrochemically active and undergo reversible oxidation during the interstitial ion extraction (Fe2+/Fe3+ and Mn2+/Mn3+). The adsorption of water results in irreversible capacity during charge but only on the Fe site, which is suggested by our chemometric analysis. The local environment of Mn experiences a substantial yet reversible Jahn–Teller effect upon interstitial ion removal because of the formation of trivalent Mn, which is associated with a decrease of the equatorial Mn−N bond lengths by 10 %.
Controllable Fabrication and Li Storage Kinetics of 1 D Spinel LiMn2O4 Positive Materials for Li‐ion Batteries: An Exploration of Critical Diameter
Authors: Zhu Chengyi , Zhang Yannan , Yu Xiaohua , Dong Peng , Duan Jianguo , Liu Jiaming , Liu Jianxiong , Zhang Yingjie 
Published: November 2019

AbstractThe morphology and size of nanoelectrode materials determine their properties. Compared to the bulk structure electrodes, 1 D electrode materials for Li‐ion batteries have been intensively studied owing to their excellent Li+ diffusion kinetics. It is generally accepted that smaller‐sized electrode materials lead to better Li storage kinetics. In this study, this is found to not be the case in 1 D LiMn2O4 positive materials. A facile strategy of manipulating the KMnO4 concentration is introduced to precisely fabricate 1 D LiMn2O4 nanorods with four distinct diameter gradients from 30 to 170 nm. The role of 1 D crystal size in effecting interface chemical species and electrochemical performance is elucidated by comparative characterization methods. X‐ray photoelectron spectroscopy (XPS) Ar‐ion etching technology shows that the Mn2+ is electrochemically inactive on the surface of the sample, which explains the adverse effects observed on LiMn2O4 nanorods with the minimum diameter of 30–40 nm, such as decreased discharge capacity. The LiMn2O4 nanorod with a critical diameter of approximately 70–80 nm displays the highest discharge capacity and promising cycling performance. This work clarifies an important property that has previously been neglected and deepens the understanding for design of Mn‐based positive materials.
FRAME routing with game theory optimization for wireless networks
Authors: Radha Subramanyam , Bala Gnanadhas Josemin , Nagabushanam Perattur 
Published: November 2019

SummaryWireless ad hoc networks have a wide variety of applications in the present world. Creating routes between the nodes and with low energy consumption is a major challenge in wireless ad hoc networks. In this paper, we have proposed FRAME routing for ad hoc networks, which consider the entire network based on hierarchal Bayesian model. It works on game theory–based Chow‐Liu algorithm for establishing routes from source to destination considering the best neighbors in the path. FRAME routing is further analyzed with SMAC and conventional MAC in various scenarios. They are also compared with conventional MAC in AODV routing in terms of energy consumption, delay, throughput, PDR, and goodput. The entire simulations are carried out using NS2 and SMAC in FRAME routing that give better performance compared with conventional MAC in FRAME, AODV routing.