bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl‐Bridged Digold Catalysts
Authors: Grirrane Abdessamad , Álvarez Eleuterio , García Hermenegildo , Corma Avelino 
Published: December 2016

AbstractTremorine and precursors of gemini surfactants were synthesised in a one‐pot, three‐step, double‐catalytic A3 coupling reaction and characterised by structural and spectroscopic methods. The cationic [AuI(L1)]SbF6 complex is a more active catalyst compared to neutral L2– and L3–AuI bis(trifluoromethanesulfonyl)imidate complexes (L1, L2=Buchwald‐type biaryl phosphane; L3=triphenylphosphine) in promoting the double A3 coupling of ethynyltrimethylsilane, secondary amines (cyclic, aliphatic, or aromatic) and formaldehyde. The solvent influences the catalytic performance by desilylation of silyl acetylene or deactivation of the catalyst by a halide anion. Acetylide‐bridged cationic digold(I) L1 and L2 complexes were isolated and characterised by means of single‐crystal X‐ray structure analysis and their spectroscopic properties. Iodine in the acetylene reagent deactivates the AuI catalyst by formation of the less active iodido‐bridged cationic digold(I) L1 complex, which was fully characterised by single‐crystal X‐ray crystal structure analysis and spectroscopy. The nature of the phosphine ligand of the gold complexes used as catalyst affects the stability and activity of the formed cationic ethynyl‐bridged AuI2–L intermediates, isolation of which lends support to the proposed double A3 coupling mechanism.
Phenyl Benzo[b]phenothiazine as a Visible Light Photoredox Catalyst for Metal‐Free Atom Transfer Radical Polymerization
Authors: Dadashi‐Silab Sajjad , Pan Xiangcheng , Matyjaszewski Krzysztof 
Published: December 2016

AbstractThis paper reports use of phenyl benzo[b]phenothiazine (Ph‐benzoPTZ) as a visible light‐induced metal‐free atom transfer radical polymerization (ATRP) photoredox catalyst. Well‐controlled polymerizations of various methacrylate monomers were conducted under a 392 nm visible light LED using Ph‐benzoPTZ to activate different alkyl halides. The use of the photocatalyst enabled temporal control over the growth of polymer chains during intermittent on/off periods. The polymerization was initiated and progressed only under stimulation by light and completely stopped in the absence of light. Block copolymers were synthesized to demonstrate high retention of chain end fidelity in the polymers and livingness of the process.
Probing the Peroxycarbenium [3+2] Cycloaddition Reactions with 1,2‐Disubstituted Ethylenes: Results and Insights
Authors: Xu Ze‐Jun , Wittlin Sergio , Wu Yikang 
Published: December 2016

AbstractThe causes for the title reaction to be limited to only the alkenes with an unsubstituted terminal alkenic carbon were explored. In some “failed” cases the cycloaddition products actually formed but rearranged concurrently. An oxygen atom or a N‐Boc (Boc=tert‐butyloxycarbonyl) group at the double bond was proven essential for acquisition of intact [3+2] cycloaddition products from 1,2‐disubstituted ethylenes.
Synchrotron X‐Ray Fluorescence Nanoprobe Reveals Target Sites for Organo‐Osmium Complex in Human Ovarian Cancer Cells
Authors: Sanchez‐Cano Carlos , Romero‐Canelón Isolda , Yang Yang , Hands‐Portman Ian J. , Bohic Sylvain , Cloetens Peter , Sadler Peter J. 
Published: December 2016

AbstractA variety of transition metal complexes exhibit anticancer activity, but their target sites in cells need to be identified and mechanisms of action elucidated. Here, it was found that the sub‐cellular distribution of [Os(η6‐p‐cym)(Azpy‐NMe2)I]+ (p‐cym=p‐cymene, Azpy‐NMe2=2‐(p‐[dimethylamino]phenylazo)pyridine) (1), a promising drug candidate, can be mapped in human ovarian cancer cells at pharmacological concentrations using a synchrotron X‐ray fluorescence nanoprobe (SXRFN). SXRFN data for Os, Zn, Ca, and P, as well as TEM and ICP analysis of mitochondrial fractions suggest localization of Os in mitochondria and not in the nucleus, accompanied by mobilization of Ca from the endoplasmic reticulum, a signaling event for cell death. These data are consistent with the ability of 1 to induce rapid bursts of reactive oxygen species and especially superoxide formed in the first step of O2 reduction in mitochondria. Such metabolic targeting differs from the action of Pt drugs, offering promise for combatting Pt resistance, which is a current clinical problem.
Exploring the Chemical Reaction Space at the Formation of Chalcogenidometalate Superspheres in Ionic Liquids
Authors: Santner Silke , Yogendra Sivathmeehan , Weigand Jan J. , Dehnen Stefanie 
Published: December 2016

AbstractThe synthesis of anionic chalcogenidometalate superspheres can be achieved from [Ge4Se10]4− salts and SnCl4 in ionic liquids with 1‐alkyl‐(2,)3‐(di)methylimidazolium cations, denoted as (Cn(C1)C1Im)+ (alkyl = butyl for n=4, hexyl for n=6, octyl for n=8). Their formation is apparently independent from the lengths of the Cn chain, and the presence or absence of a second methyl group at the ionic liquid cation (that are exchanged for alkali metal cations in precursor compounds during the reactions), although this may appear counterintuitive. In contrast, and equally counterintuitive, the ionic liquid anion was found to play a crucial role for both the general observability as well as the crystal yield and quality of the products, although they are not part of the product: a minimum content of chloride is needed, while ionic liquids with [BF4]− anions alone do not support the product formation/crystallization. The observation suggests a subtle equilibrium of SnCl4 with according halidostannate anions that decreases the reactivity of the tin source. The finding is of particular interest, as chloride anions were shown to have been major impurities of former “chloride‐free” ionic liquid charges, which potentially led to irreproducible synthesis protocols in the literature.
A Very Short Be–Be Distance but No Bond: Synthesis and Bonding Analysis of Ng–Be2O2–Ng′ (Ng, Ng′=Ne, Ar, Kr, Xe)
Authors: Zhang Qingnan , Li Wan‐Lu , Zhao Lili , Chen Mohua , Zhou Mingfei , Li Jun , Frenking Gernot 
Published: December 2016

AbstractShort interatomic distances below standard values for a single bond are usually identified with double or triple bonds. The synthesis and spectroscopic characterization of a molecule is reported where the distance between two beryllium atoms is shorter than a standard double bond but there is no bond. The cyclic diberyllium dioxide Be2O2molecule, which is coordinated by two noble gas atoms in Ng−Be2O2−Ng′ (Ng, Ng′=Ne, Ar, Kr, Xe) was isolated and spectroscopically identified in low‐temperature matrices. The complexes possess very short Be−Be distances, but the analysis of the electronic structure reveals that there is no chemical bond.
Enantioselective Tandem Oxidation/Michael–Aldol Approaches to Tetrasubstituted Cyclohexanes
Authors: Rana Nirmal K. , Joshi Harshit , Jha Rupesh K. , Singh Vinod K. 
Published: December 2016

AbstractEnantioselective tandem Michael–aldol and oxidative Michael–aldol approaches have been achieved for the formation of diversely substituted cyclohexanes in total regio‐, diastereo‐ and enantioselective fashion. The presence of nitro, hydroxy and keto groups in the product provides a wide scope for further structural transformations. Furthermore, the utility of the catalytic process is demonstrated in the context of enantioselective formal synthesis of ABT‐341, a DPP4 inhibitor.
Stereoselective bioaccumulation, transformation, and toxicity of triadimefon in Scenedesmus obliquus
Authors: Xu Peng , Huang Ledan 
Published: December 2016

AbstractIn this study the stereoselective bioaccumulation and transformation of triadimefon and the toxicity of triadimefon and its metabolite triadimenol to the green algae Scenedesmus obliquus were studied. In growth inhibition experiments, triadimenol was more toxic than triadimefon, and (1S,2R)‐triadimenol, which has the largest fungicidal activity, presented the highest toxicity to the algae. In bioaccumulation experiments, triadimefon was rapidly taken up by algae cells, and the decrease in the concentration of triadimefon was accompanied by an increase in triadimenol. The transformation of S‐(+)‐ triadimefon was faster than that of the R‐(−)‐enantiomer, resulting in four triadimenol stereoisomers at different forming rates: B2 (1S, 2S) > B1 (1R, 2R) > A2 (1S, 2R) > A1 (1R, 2S). Thus, it is necessary to explore the enantioselective toxicology and ecological fate of these chiral pesticides in an environmental risk assessment. Also, their metabolites should be paid specific attention to since they may pose higher ecological risks.
Gas holdup, bubble behaviour, and mass transfer characteristics in a two‐stage internal loop airlift reactor with different screens
Authors: Zhang Xiaobo , Guo Kai , Qi Wenzhe , Zhang Ting , Liu Chunjiang 
Published: December 2016

AbstractScreen internals were used in a two‐dimensional two‐stage internal loop airlift reactor (ILALR). The influence of screens on the hydrodynamics and mass transfer characteristics in the two‐stage ILALR, including gas holdup, mean bubble diameter, bubble rise velocity, and volumetric mass transfer coefficient (KLa), have been experimentally investigated. It is found that screens can efficiently break bubbles up. Radial bubble velocity distribution is more uniform when screens are installed. Mean bubble diameter with smaller screen pores seems smaller and slightly increases with the increasing of superficial gas velocity Ug. A larger gas holdup and KLa can be obtained when a suitable screen is mounted. The variation trend of overall gas holdup and interfacial area a with Ug is similar. A nearly constant liquid‐side mass transfer coefficient (KL) is found. The empirical correlations for the overall gas holdup and KLa have been proposed, which fit the experimental data well.
Sacrificial Templating Fabrication of Hierarchically Porous Nitrogen‐Doped Carbon Nanosheets as Superior Oxygen Reduction Electrocatalysts
Authors: Huang Tao , Yang Chongqing , Wang Xinjing , Qiu Feng , Jing Fan , Jiang Jianzhong , Liu Ruili , Han Sheng , Wu Dongqing 
Published: December 2016

AbstractAn unprecedented sacrificial templating strategy towards hierarchically porous N‐doped carbon nanosheets (PNC‐A) proceeds by the thermal treatment of the graphene hybrid coated with polyaniline‐encapsulated tin oxide nanoparticles, and the following etching process with acid and NH3. The resultant PNC‐A exhibits well‐defined 2D morphology, high ratio of graphitic N and pyridinic N atoms as the active sites, and hierarchically porous structures with high specific surface area. Serving as the electrocatalyst for oxygen reduction reaction (ORR) in basic media, PNC‐A exhibits excellent catalytic activity via a four‐electron pathway with half‐wave potentials of 0.76 V vs. RHE electrode in alkaline media; the diffusion‐limiting current density is 5.48 mA cm−2, which is superior to most of the reported metal‐free ORR catalysts and comparable to state‐of‐the‐art Pt/C.
Structure and Optical Properties of Carbon Nanoparticles Generated by Laser Treatment of Graphite in Liquids
Authors: Tarasenka Natalie , Stupak Aleksandr , Tarasenko Nikolai , Chakrabarti Supriya , Mariotti Davide 
Published: December 2016

AbstractIn this paper, we report the one‐step synthesis of luminescent carbon nanoparticles (NPs) via laser irradiation of a graphite target in a solvent [H2O, ethanol, or a 0.008 m aqueous diethylenetriaminepentaacetic acid (DTPA) solution]. This is a simple approach for the fabrication of carbon dots with tunable photoluminescence (PL) that differs from other preparation methods, as no post‐passivation step is required. The unfocused beam of the second harmonic (wavelength 532 nm) of the Nd:YAG laser was used in our experiments. The sizes of the prepared NPs were mainly distributed in the range of 1–8 nm with an average value of 3 nm. Carbon NPs of different inner structure were prepared: hexagonal diamond phase in aqueous DTPA solution, orthorhombic carbon phase in ethanol, and amorphous carbon in water. The synthesized carbon NPs have strong luminescence in the visible region, which makes them attractive for numerous biological applications. The photoluminescence of the synthesized NPs was investigated at different excitation wavelengths, from 260 to 450 nm. The highest intensities of the emission bands were detected for an excitation wavelength of 400 nm.
Large‐Scale Quantum Many‐Body Perturbation on Spin and Charge Separation in the Excited States of the Synthesized Donor–Acceptor Hybrid PBI–Macrocycle Complex
Authors: Ziaei Vafa , Bredow Thomas 
Published: December 2016

AbstractThe reliable calculation of the excited states of charge‐transfer (CT) compounds poses a major challenge to the ab initio community because the frequently employed method, time‐dependent density functional theory (TD‐DFT), massively relies on the underlying density functional, resulting in heavily Hartree–Fock (HF) exchange‐dependent excited‐state energies. By applying the highly sophisticated many‐body perturbation approach, we address the encountered unreliabilities and inconsistencies of not optimally tuned (standard) TD‐DFT regarding photo‐excited CT phenomena, and present results concerning accurate vertical transition energies and the correct energetic ordering of the CT and the first visible singlet state of a recently synthesized thermodynamically stable large hybrid perylene bisimide–macrocycle complex. This is a large‐scale application of the quantum many‐body perturbation approach to a chemically relevant CT system, demonstrating the system‐size independence of the quality of the many‐body‐based excitation energies. Furthermore, an optimal tuning of the ωB97X hybrid functional can well reproduce the many‐body results, making TD‐DFT a suitable choice but at the expense of introducing a range‐separation parameter, which needs to be optimally tuned.
Catalytic Activity of Gold(I) Complexes with Hemilabile P,N Ligands
Authors: Michelet Bastien , Lebœuf David , Bour Christophe , Škoch Karel , Horký Filip , Štěpnička Petr , Gandon Vincent 
Published: December 2016

AbstractTwo new cationic dinuclear gold(I) complexes, [Au2{μ(P,N)‐5}2]X2—in which X=NTf2 (7; Tf=trifluoromethanesulfonate) or SbF6 (8) and 2‐(diphenylphosphanyl)benzonitrile (5) is a P,N‐bridging donor—have been synthesized and structurally characterized. These air‐stable species and their dimeric and polymeric analogues possessing 1′‐(diphenylphosphanyl)‐1‐cyanoferrocene (1) as the bridging ligand, [Au2{μ(P,N)‐1}2](NTf2)2 and [Au{μ(P,N)‐1}]n[SbF6]n, were used as precatalysts in various Au‐mediated C−C and C−O bond‐forming reactions. The reactivity of these complexes revealed the hemilabile nature of their P,N ligands. In the series of tested precatalysts, complex 8 exerted particularly high catalytic activity at low Au loading, even in reactions that usually require high amounts of gold catalyst to proceed efficiently under standard reaction conditions.
Simultaneous automatic scoring and co‐registration of hormone receptors in tumor areas in whole slide images of breast cancer tissue slides
Authors: Trahearn Nicholas , Tsang Yee Wah , Cree Ian A. , Snead David , Epstein David , Rajpoot Nasir 
Published: December 2016

AbstractAutomation of downstream analysis may offer many potential benefits to routine histopathology. One area of interest for automation is in the scoring of multiple immunohistochemical markers to predict the patient's response to targeted therapies. Automated serial slide analysis of this kind requires robust registration to identify common tissue regions across sections. We present an automated method for co‐localized scoring of Estrogen Receptor and Progesterone Receptor (ER/PR) in breast cancer core biopsies using whole slide images. Regions of tumor in a series of fifty consecutive breast core biopsies were identified by annotation on H&E whole slide images. Sequentially cut immunohistochemical stained sections were scored manually, before being digitally scanned and then exported into JPEG 2000 format. A two‐stage registration process was performed to identify the annotated regions of interest in the immunohistochemistry sections, which were then scored using the Allred system. Overall correlation between manual and automated scoring for ER and PR was 0.944 and 0.883, respectively, with 90% of ER and 80% of PR scores within in one point or less of agreement. This proof of principle study indicates slide registration can be used as a basis for automation of the downstream analysis for clinically relevant biomarkers in the majority of cases. The approach is likely to be improved by implantation of safeguarding analysis steps post registration. © 2016 International Society for Advancement of Cytometry
Proportion of circulating tumor cell clusters increases during cancer metastasis
Authors: Suo Yuanzhen , Xie Chengying , Zhu Xi , Fan Zhichao , Yang Zhangru , He Hao , Wei Xunbin 
Published: December 2016

AbstractCirculating tumor cell (CTC) clusters are found among CTCs and show significantly greater potential for an important role in cancer metastasis than single CTCs, which have been traditionally believed as the majority of CTCs. The accurate proportion and dynamics of CTC clusters remain unclear due to the fact that CTCs in blood flow are very difficult to detect in vivo and in vitro. CTC clusters are even more difficult to be distinguished from CTCs without perturbation by state‐of‐the‐art detection methods. Here, we demonstrate that by using in vivo flow cytometry (IVFC), we can reliably measure the proportion and dynamics of CTC clusters in two murine tumor models. CTC clusters are easily identified by their unique fluorescent pattern with multiple peaks and wider time duration. We find that the proportion of CTC clusters increases significantly during cancer metastasis in both mouse models, the orthotopic liver cancer and the subcutaneous prostate cancer models. Our results suggest that CTC clusters account for a much larger proportion of CTCs than previously anticipated. Hence this report might provide a new‐level of understanding of CTCs during cancer development and progression. © 2016 International Society for Advancement of Cytometry
Offshore aquaculture: Spatial planning principles for sustainable development
Authors: Gentry Rebecca R. , Lester Sarah E. , Kappel Carrie V. , White Crow , Bell Tom W. , Stevens Joel , Gaines Steven D. 
Published: December 2016

AbstractMarine aquaculture is expanding into deeper offshore environments in response to growing consumer demand for seafood, improved technology, and limited potential to increase wild fisheries catches. Sustainable development of aquaculture will require quantification and minimization of its impacts on other ocean‐based activities and the environment through scientifically informed spatial planning. However, the scientific literature currently provides limited direct guidance for such planning. Here, we employ an ecological lens and synthesize a broad multidisciplinary literature to provide insight into the interactions between offshore aquaculture and the surrounding environment across a spectrum of spatial scales. While important information gaps remain, we find that there is sufficient research for informed decisions about the effects of aquaculture siting to achieve a sustainable offshore aquaculture industry that complements other uses of the marine environment.
Can spatial sorting associated with spawning migration explain evolution of body size and vertebral number inAnguillaeels?
Authors: Forsman Anders , Berggren Hanna 
Published: December 2016

AbstractSpatial sorting is a process that can contribute to microevolutionary change by assembling phenotypes through space, owing to nonrandom dispersal. Here we first build upon and develop the “neutral” version of the spatial sorting hypothesis by arguing that in systems that are not characterized by repeated range expansions, the evolutionary effects of variation in dispersal capacity and assortative mating might not be independent of but interact with natural selection. In addition to generating assortative mating, variation in dispersal capacity together with spatial and temporal variation in quality of spawning area is likely to influence both reproductive success and survival of spawning migrating individuals, and this will contribute to the evolution of dispersal‐enhancing traits. Next, we use a comparative approach to examine whether differences in spawning migration distance among 18 species of freshwaterAnguillaeels have evolved in tandem with two dispersal‐favoring traits. In our analyses, we use information on spawning migration distance, body length, and vertebral number that was obtained from the literature, and a published whole mitochondrialDNA‐based phylogeny. Results from comparative analysis of independent contrasts showed that macroevolutionary shifts in body length throughout the phylogeny have been associated with concomitant shifts in spawning migration. Shifts in migration distance were not associated with shifts in number of vertebrae. These findings are consistent with the hypothesis that spatial sorting has contributed to the evolution of more elongated bodies in species with longer spawning migration distances, or resulted in evolution of longer migration distances in species with larger body size. This novel demonstration is important in that it expands the list of ecological settings and hierarchical levels of biological organization for which the spatial sorting hypothesis seems to have predictive power.
Microsite and grazing intensity drive infiltration in a semiarid woodland
Authors: Vandandorj Sumiya , Eldridge David J. , Travers Samantha K. , Val James , Oliver Ian 
Published: December 2016

AbstractHuman activities such as vegetation removal and overgrazing that result in changes in land cover have substantial impacts on ecosystem processes, including the infiltration of water. Different land cover types (microsites) vary in their capacity to conduct water, but the extent to which infiltration is affected by different herbivores or microsites is largely unknown. We examined the effects of grazing and microsite on infiltration in two extensive woodland communities in semiarid eastern Australia that vary in current condition. Poor condition sites had lower steady‐state infiltration under ponding than either average or good condition sites, and this effect was consistent across the two communities. Ponded infiltration and sorptivity beneath grasses, shrubs or trees were about twice that on bare soil, and this corresponded to greater indices of macroporosity. Structural equation modelling showed that shrubs, trees, and grasses had strong positive effects on sorptivity and steady‐state infiltration under ponding, whereas grazing had generally negative effects. The suppressive effects of grazing on soil hydrological processes were mainly due to cattle grazing. The positive effects of grasses, shrubs, and trees on hydrology were twice as strong as the negative effects of grazing. Our results also suggest that prolonged overgrazing that leads to reductions in grass cover is likely to have a synergistic reduction in hydrological function in these woodlands by reducing the cover of highly conductive patches and by reducing the extent of macropores.