bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regioselective C−H Xanthylation as a Platform for Polyolefin Functionalization
Authors: Williamson Jill B. , Czaplyski William L. , Alexanian Erik J. , Leibfarth Frank A. 
Published: April 2018

AbstractPolyolefins that contain polar functional groups are important materials for next‐generation lightweight engineering thermoplastics. Post‐polymerization modification is an ideal method for the incorporation of polar groups into branched polyolefins; however, it typically results in chain scission events, which have deleterious effects on polymer properties. Herein, we report a metal‐free method for radical‐mediated C−H xanthylation that results in the regioselective functionalization of branched polyolefins without coincident polymer‐chain scission. This method enables a tunable degree of polymer functionalization and capitalizes on the versatility of the xanthate functional group to unlock a wide variety of C−H transformations previously inaccessible on branched polyolefins.
Enantioselective Formation of 2‐Azetidinones by Ring‐Assisted Cyclization of Interlocked N‐(α‐Methyl)benzyl Fumaramides
Authors: Martinez‐Cuezva Alberto , Bautista Delia , Alajarin Mateo , Berna Jose 
Published: April 2018

AbstractThe synthesis of optically active interlocked and non‐interlocked 2‐azetidinones by intramolecular cyclization of N‐(α‐methyl)benzyl fumaramide [2]rotaxanes is described. Two different strategies of asymmetric induction were tested in which the chiral group was located either proximal or distal to the reacting center of the thread. During these experiments, an interesting equilibration process inside the macrocyclic void occurred, thus leading to the cyclization through the (α‐methyl)benzyl carbon atom and giving rise to β‐lactams, with a quaternary carbon atom, in an enantio‐ and diastereocontrolled manner. This cyclization also proceeds in kinetically stable chiral pseudo[2]rotaxanes, thus allowing further dethreading to provide enantioenriched 3,4‐disubstituted trans‐2‐azetidinones. The stereochemical outcomes of the cyclizations inside and outside the macrocycle demonstrated noticeable differences.
Catholyte‐Free Electrocatalytic CO2 Reduction to Formate
Authors: Lee Wonhee , Kim Young Eun , Youn Min Hye , Jeong Soon Kwan , Park Ki Tae 
Published: April 2018

AbstractElectrochemical reduction of carbon dioxide (CO2) into value‐added chemicals is a promising strategy to reduce CO2 emission and mitigate climate change. One of the most serious problems in electrocatalytic CO2 reduction (CO2R) is the low solubility of CO2 in an aqueous electrolyte, which significantly limits the cathodic reaction rate. This paper proposes a facile method of catholyte‐free electrocatalytic CO2 reduction to avoid the solubility limitation using commercial tin nanoparticles as a cathode catalyst. Interestingly, as the reaction temperature rises from 303 K to 363 K, the partial current density (PCD) of formate improves more than two times with 52.9 mA cm−2, despite the decrease in CO2 solubility. Furthermore, a significantly high formate concentration of 41.5 g L−1 is obtained as a one‐path product at 343 K with high PCD (51.7 mA cm−2) and high Faradaic efficiency (93.3 %) via continuous operation in a full flow cell at a low cell voltage of 2.2 V.
Reversible Response of Luminescent Terbium(III)–Nanocellulose Hydrogels to Anions for Latent Fingerprint Detection and Encryption
Authors: Hai Jun , Li Tianrong , Su Junxia , Liu Weisheng , Ju Yanmin , Wang Baodui , Hou Yanglong 
Published: April 2018

AbstractFingerprint fluorescence imaging has become one of the most prominent technologies in the field of forensic medicine, but it seldom considers the security protection of detection information, which is of great importance in modern society. Herein we demonstrate that luminescent TbIII–carboxymethyl cellulose (CMC) complex binding aptamer hydrogels that are reversibly responsive to ClO−/SCN− can be used for the selective detection, protection, and storage of fingerprint information. The imaging information of the fingerprint can be quenched and recovered by ClO−/SCN− regulation, respectively, resulting in reversible on/off conversion of the luminescence signals for the encryption and decryption of multiple levels of information. The present study opens new avenues for multilevel imaging, data recording, and security protection of fingerprint information with tunable fluorescent hydrogels.
Selective Hydrogenation of CO2 to Ethanol over Cobalt Catalysts
Authors: Wang Lingxiang , Wang Liang , Zhang Jian , Liu Xiaolong , Wang Hai , Zhang Wei , Yang Qi , Ma Jingyuan , Dong Xue , Yoo Seung Jo , Kim Jin‐Gyu , Meng Xiangju , Xiao Feng‐Shou 
Published: April 2018

AbstractMethods for the hydrogenation of CO2 into valuable chemicals are in great demand but their development is still challenging. Herein, we report the selective hydrogenation of CO2 into ethanol over non‐noble cobalt catalysts (CoAlOx), presenting a significant advance for the conversion of CO2 into ethanol as the major product. By adjusting the composition of the catalysts through the use of different prereduction temperatures, the efficiency of CO2 to ethanol hydrogenation was optimized; the catalyst reduced at 600 ° gave an ethanol selectivity of 92.1 % at 140 °C with an ethanol time yield of 0.444 mmol g−1 h−1. Operando FT‐IR spectroscopy revealed that the high ethanol selectivity over the CoAlOx catalyst might be due to the formation of acetate from formate by insertion of *CHx, a key intermediate in the production of ethanol by CO2 hydrogenation.
Organocatalytic Atroposelective Intramolecular [4+2] Cycloaddition: Synthesis of Axially Chiral Heterobiaryls
Authors: Liu Yidong , Wu Xiaoyan , Li Shan , Xue Lu , Shan Chunhui , Zhao Zhengxing , Yan Hailong 
Published: April 2018

AbstractThe enantioselective construction of axially chiral aryl‐naphthopyran skeletons was realized by organocatalytic atroposelective intramolecular [4+2] cycloaddition of in situ generated vinylidene ortho‐quinone methides, from 2‐ethynylphenol derivatives, with alkynes. Through this method, the heteroatropisomers were obtained with excellent yields and enantioselectivities. Moreover, a speculative model of the stereochemical outcome is proposed based on preliminary mechanistic studies. The products having various functional groups can be easily transformed into valuable intermediates as either potential ligands or organocatalysts.
Direct Aryloxylation/Alkyloxylation of Dialkyl Phosphonates for the Synthesis of Mixed Phosphonates
Authors: Huang Hai , Denne Johanna , Yang Chou‐Hsun , Wang Haobin , Kang Jun Yong 
Published: April 2018

AbstractA strategy for the direct functionalization strategy of inertial dialkyl phosphonates with hydroxy compounds to afford diverse mixed phosphonates with good yields and functional‐group tolerance has been developed. Mechanistic investigations involving both NMR studies and DFT studies suggest that an unprecedented highly reactive PV species (phosphoryl pyridin‐1‐ium salt), a key intermediate for this new synthetic transformation, is generated in situ from dialkyl phosphonate in the presence of Tf2O/pyridine.
Design of Trifluoroalkenyl Iodonium Salts for a Hypervalency‐Aided Alkenylation–Cyclization Strategy: Metal‐Free Construction of Aziridine Rings
Authors: Mészáros Ádám , Székely Anna , Stirling András , Novák Zoltán 
Published: April 2018

AbstractThe synthesis of fluorinated compounds and their use as pharmaceutical ingredients or synthetic building blocks have been in the focus of chemical and medicinal research. However, the efficient synthesis of trifluoromethylated nitrogen heterocycles is sometimes challenging. Herein, we disclose a simple aziridination process that relies on the use of amines and novel alkenyl iodonium reagents for the synthesis of strained, trifluoromethylated heterocycles. With the utilization of a newly designed and bench‐stable but highly reactive hypervalent alkenyl iodonium species, these three‐membered‐ring heterocyclic compounds can be efficiently constructed from simple amines under mild conditions in the absence of transition‐metal catalysts. The special reactivity of the new trifluoropropenyl synthon towards nucleophilic centers could be exploited in more general cyclization and alkenylation reactions in the future.
CuH‐Catalyzed Asymmetric Hydroamidation of Vinylarenes
Authors: Zhou Yujing , Engl Oliver D. , Bandar Jeffrey S. , Chant Emma D. , Buchwald Stephen L. 
Published: April 2018

AbstractA CuH‐catalyzed enantioselective hydroamidation reaction of vinylarenes has been developed using readily accessible 1,4,2‐dioxazol‐5‐ones as electrophilic amidating reagents. This method provides a straightforward and efficient approach to synthesize chiral amides in good yields with high levels of enantiopurity under mild conditions. Moreover, this transformation tolerates substrates bearing a broad range of functional groups.
Cobalt‐Catalyzed Intramolecular Reactions between a Vinylcyclopropane and an Alkyne: Switchable [5+2] Cycloaddition and Homo‐Ene Pathways
Authors: Wu Chunlin , Yoshikai Naohiko 
Published: April 2018

AbstractCobalt–diphosphine catalysts have been found to promote intramolecular reactions between a vinylcyclopropane and an alkyne to selectively afford either the [5+2] cycloaddition product or the homo‐ene reaction product under solvent control. The former product is exclusively formed in noncoordinating 1,2‐dichloroethane, whereas the latter is dominant in coordinating solvents, such as acetonitrile and dimethylacetamide. Furthermore, a highly enantioselective variant of the homo‐ene reaction afforded chiral tetrahydrofuran, pyrrolidine, and cyclopentane derivatives bearing 1,3‐diene and alkylidene substituents.
Electrochemical Functional‐Group‐Tolerant Shono‐type Oxidation of Cyclic Carbamates Enabled by Aminoxyl Mediators
Authors: Wang Fei , Rafiee Mohammad , Stahl Shannon S. 
Published: April 2018

AbstractAn electrochemical method has been developed for α‐oxygenations of cyclic carbamates by using a bicyclic aminoxyl as a mediator and water as the nucleophile. The mediated electrochemical process enables substrate oxygenation to proceed at a potential that is approximately 1 V lower than the redox potential of the carbamate substrate. This feature allows for functional‐group compatibility that is inaccessible with conventional Shono oxidations, which proceed by direct electrochemical substrate oxidation. This reaction also represents the first α‐functionalization of non‐activated cyclic carbamates with oxoammonium oxidants.
Variation among macroinvertebrate communities suggests the importance of conserving desert springs
Authors: Stanislawczyk Keara , Walters Ashley D. , Haan Tara J. , Sei Makiri , Lang Brian K. , Berg David J. 
Published: April 2018

AbstractDesert springs are highly threatened ecosystems inhabited by a substantial number of endemic species.Macroinvertebrate communities of five springs in the northern Chihuahuan Desert of west Texas and south‐eastern New Mexico were sampled seasonally. Rather than focusing on individual taxa, this study examined the community structure of springs to identify patterns that are likely to reflect both local conditions and potential dispersal barriers.In total, 46 774 individuals representing 109 taxa were collected with high relative abundances of gastropods, amphipods, and oligochaetes. Spatial variation in community composition was greater than temporal variation.Although there were differences in the salinity content and concentrations of several major anions and cations among sites, these were not significant predictors of difference in community structure. Two springs sharing the same groundwater source contained similar macroinvertebrate communities and had similar physicochemical conditions. Results from this study suggest that springs in the northern Chihuahuan Desert contain unique communities and endemic species owing to historical processes such as isolation and dispersal limitation, rather than contemporary processes such as environmental filtering and species sorting.Springs located in the northern Chihuahuan Desert, like those located in other arid regions of the world, are valuable for their biodiversity because of their distinct invertebrate communities and high rates of endemism. Thus, they should be conserved individually to ensure the preservation of unique species and communities.
An investigation of salmonid host utilization by the endangered freshwater pearl mussel (Margaritifera margaritifera) in north‐west Scotland
Authors: Clements Elizabeth A. , Thomas Rhian , Adams Colin E. 
Published: April 2018

Abstract

The complex life cycle of the globally threatened Margaritifera margaritifera includes a parasitic stage, where glochidia attach to the gills of fishes of the genus Salmo; however, the species of Salmo used appears to vary across its range. In previous literature the reported primary host in Scotland, home to a high proportion of the world's remaining M. margaritifera populations, is the Atlantic salmon Salmo salar, and in its absence the brown trout Salmo trutta.
In this study, the prevalence of infection in putative Salmo hosts in eight rivers in north‐west Scotland was determined. At a selected site on each river, where both S. trutta and S. salar were collected in abundance, S. trutta was the preferred host.
At sites where S. salar were abundant but S. trutta were at low density, however, S. salar showed a high prevalence of infection (with the exception of one river where neither S. salar nor S. trutta were infected). Thus, the primary host appears to be very site‐specific in the rivers sampled.
We speculate that this may be because M. margaritifera have population‐specific responses to cues for attachment to a host. Alternatively, it may be that host population‐specific immune responses mediate infections by glochidia. In addition, larger fish were less likely to be infected than smaller fish, and gills 1 and 5 were less heavily infected than gills 2–4.
One consequence of this finding, for both national and international conservation management of this globally endangered species, is that any current or future management activity must take into account local population host preferences, otherwise conservation efforts may be in vain.
Development and Functional Organization of the Cranial Nerves in Lampreys
Authors: Pombal Manuel A. , Megías Manuel 
Published: April 2018

ABSTRACTLampreys, together with hagfishes, are the only extant representatives of the oldest branch of vertebrates, the agnathans, which are the sister group of gnathostomes; therefore, studies on these animals are of great evolutionary significance. Lampreys exhibit a particular life cycle with remarkable changes in their behavior, concomitant, in part, with important modifications in the head and its musculature, which might influence the development of the cranial nerves. In this context, some cranial nerves such as the optic nerve and the ocular motor nerves, which develop slowly during an extremely long larval period lasting more than five years, have been more thoroughly investigated; however, much less experimental information is available about others, such as the facial or the hypoglossal nerves. In addition, the possible existence of a “true” accessory nerve in these animals is still a matter of conjecture. Although growing in last decades, investigations on the physiology of the lamprey cranial nerves is scanty. This review focuses on past and recent findings that have contributed to characterize the anatomical organization of the cranial nerves in lampreys, including their components and nuclei, and their relations in the brain; in addition, comments on their development and functional role are also included. Anat Rec, 302:512–539, 2019. © 2018 Wiley Periodicals, Inc.
Hypochlorite‐Mediated Modulation of Photoinduced Electron Transfer in a Phenothiazine–Boron dipyrromethene Electron Donor–Acceptor Dyad: A Highly Water Soluble “Turn‐On” Fluorescent Probe for Hypochlorite
Authors: Soni Disha , Duvva Naresh , Badgurjar Deepak , Roy Tapta Kanchan , Nimesh Surendra , Arya Geeta , Giribabu Lingamallu , Chitta Raghu 
Published: April 2018

AbstractA highly water‐soluble phenothiazine (PTZ)–boron dipyrromethene (BODIPY)‐based electron donor–acceptor dyad (WS‐Probe), which contains BODIPY as the signaling antennae and PTZ as the OCl− reactive group, was designed and used as a fluorescent chemosensor for the detection of OCl−. Upon addition of incremental amounts of NaOCl, the quenched fluorescence of WS‐Probe was enhanced drastically, which indicated the inhibition of reductive photoinduced electron transfer (PET) from PTZ to 1BODIPY*; the detection limit was calculated to be 26.7 nm. Selectivity studies with various reactive oxygen species, cations, and anions revealed that WS‐Probe was able to detect OCl− selectively. Steady‐state fluorescence studies performed at varied pH suggested that WS‐Probe can detect NaOCl and exhibits maximum fluorescence in the pH range of 7 to 8, similar to physiological conditions. ESI‐MS analysis and 1H NMR spectroscopy titrations showed the formation of sulfoxide as the major oxidized product upon addition of hypochlorite. More interestingly, when WS‐Probe was treated with real water samples, the fluorescence response was clearly visible with tap water and disinfectant, which indicated the presence of OCl− in these samples. The in vitro cell viability assay performed with human embryonic kidney 293 (HEK 293) cells suggested that WS‐probe is non‐toxic up to 10 μm and implicates the use of the probe for biological applications.
Ruthenium(II)−Bipyridine/NanoC3N4 Hybrids: Tunable Photochemical Properties by Using Exchangeable Alkali Metal Cations
Authors: Mori Kohsuke , Tatsumi Daisuke , Iwamoto Tomoyuki , Masui Yoichi , Onaka Makoto , Yamashita Hiromi 
Published: April 2018

AbstractA series of nanoporous carbon nitrides that contained a range of alkali metal cations (M@nanoC3N4: M=Li+, Na+, K+, Rb+, and Cs+) have been successfully synthesized from as‐synthesized g‐C3N4 by delamination with concentrated sulfuric acid, followed by neutralization with aqueous solutions of the corresponding alkali metal hydroxides. Tris(2,2′‐bipyridine)ruthenium(II) complexes, [Ru(bpy)3]2+, were grafted onto the carbon nitrides in an effort to explore the physicochemical properties of the deposited [Ru(bpy)3]2+, as well as its photocatalytic activity in the aerobic photooxidation of phenylboronic acid and H2 production from aqueous media in the presence of a Pt co‐catalyst under visible‐light irradiation. Highly porous nanoC3N4 could significantly enhance photocatalytic activity, because of its high surface area, owing to its unique porous structure. More interestingly, the photoluminescence intensities of [Ru(bpy)3]2+ complexes that were associated with M@nanoC3N4 increased in the presence of lighter alkali metal cations, which correlated with increased photocatalytic activities for both reactions. This study demonstrates that M@nanoC3N4 are fascinating supports, in which the local environment of an immobilized metal complex can be precisely controlled by varying the alkali metal cation from Li+ to Cs+.
Vergleichende Betrachtung klimatischer Referenzdatensätze hinsichtlich ihres Einflusses auf die energetische Simulation eines Gebäudes
Authors: Schöner Tobias , Zirkelbach Daniel 
Published: April 2018

AbstractDie Bedeutung von Simulationen des Bauteil‐ und Gebäudeverhaltens als Teil einer ganzheitlichen Betrachtung im Rahmen des Building Information Modeling (BIM) nimmt stetig zu. Die Qualität der erzeugten Ergebnisse wird dabei maßgeblich von den gewählten klimatischen Randbedingungen bestimmt. Derzeit ist der Anwender dazu gezwungen, abhängig von der Fragestellung unterschiedliche klimatische Referenzdatensätze für seine Simulation zu verwenden. In diesem Beitrag wird die Auswirkung unterschiedlicher deutscher Referenzklimata auf den Gebäudeenergiebedarf eines Beispielgebäudes näher betrachtet. Für den Vergleich werden die stationären Heizgradtage sowie das instationäre Gebäudeverhalten bei Verwendung unterschiedlicher Randbedingungen miteinander verglichen. Abschließend werden die mit den Referenzdatensätzen erzeugten Ergebnisse in Relation zu den natürlich auftretenden klimatischen Schwankungen gesetzt.
Systematic review of the influence of socioeconomic deprivation on mortality after colorectal surgery
Authors: Poulton T E , Salih T , Martin P , Rojas-Garcia A , Raine R , Moonesinghe S R 
Published: April 2018

Abstract

Background
Socioeconomic deprivation is a potentially important factor influencing surgical outcomes. This systematic review aimed to summarize the evidence for any association between socioeconomic group and mortality after colorectal surgery, and to report the definitions of deprivation used and the approaches taken to adjust for co-morbidity in this patient population.

Methods
MEDLINE, Embase, the Cochrane Library and Web of Science were searched for studies up to November 2016 on adult patients undergoing major colorectal surgery, which reported on mortality according to socioeconomic group. Risk of bias and study quality were assessed by extracting data relating to study size, and variations in inclusion and exclusion criteria. Quality was assessed using a modification of a previously described assessment tool.

Results
The literature search identified 59 studies published between 1993 and 2016, reporting on 2 698 403 patients from eight countries. Overall findings showed evidence for higher mortality in more deprived socioeconomic groups, both in the perioperative period and in the longer term. Studies differed in how they defined socioeconomic groups, but the most common approach was to use one of a selection of multifactorial indices based on small geographical areas. There was no consistent approach to adjusting for co-morbidity but, where this was considered, the Charlson Co-morbidity Index was most frequently used.

Conclusion
This systematic review suggests that socioeconomic deprivation influences mortality after colorectal surgery.
With a little help from a stranger: The impact of external change agents on corporate sustainability investments
Authors: Hoppmann Joern , Sakhel Alice , Richert Marcel 
Published: April 2018

AbstractWe investigate the role external change agents (e.g., consultants), play in stimulating corporate sustainability investments. Using data on more than 5,300 energy efficiency investment decisions by 462 firms, we find that firms that draw more strongly on external change agents seize significantly more sustainable investment opportunities. We show that external change agents are more effective in stimulating investments if they broadly search for investment opportunities and are more strongly involved in the implementation of change initiatives. Moreover, surprisingly, we do not find that using internal change agents in parallel with external agents enhances the effectiveness of external change agents. Our findings have important implications for the literature on corporate sustainability as they point to external change agents as an important means of steering firms onto more sustainable pathways. Additionally, we shed light on the conditions under which external change agents can be used to most effectively overcome organizational path dependencies.