bluuebunny/crossref_metadata_2025 huggingface dataset:
Variability in under‐ice export fluxes of biogenic matter in the Arctic Ocean
Authors: Lalande Catherine , Nöthig Eva‐Maria , Somavilla Raquel , Bauerfeind Eduard , Shevchenko Vladimir , Okolodkov Yuri
Published: May 2014

A critical question regarding the organic carbon cycle in the Arctic Ocean is whether the decline in ice extent and thickness and the associated increase in solar irradiance in the upper ocean will result in increased primary production and particulate organic carbon (POC) export. To assess spatial and temporal variability in POC export, under‐ice export fluxes were measured with short‐term sediment traps in the northern Laptev Sea in July‐August‐September 1995, north of the Fram Strait in July 1997, and in the Central Arctic in August–September 2012. Sediment traps were deployed at 2–5 m and 20–25 m under ice for periods ranging from 8.5 to 71 h. In addition to POC fluxes, total particulate matter, chlorophyll a, biogenic particulate silica, phytoplankton, and zooplankton fecal pellet fluxes were measured to evaluate the amount and composition of the material exported in the upper Arctic Ocean. Whereas elevated export fluxes observed on and near the Laptev Sea shelf were likely the combined result of high primary production, resuspension, and release of particulate matter from melting ice, low export fluxes above the central basins despite increased light availability during the record minimum ice extent of 2012 suggest that POC export was limited by nutrient supply during summer. These results suggest that the ongoing decline in ice cover affects export fluxes differently on Arctic shelves and over the deep Arctic Ocean and that POC export is likely to remain low above the central basins unless additional nutrients are supplied to surface waters.
Geomagnetic activity effect on the global ionosphere during the 2007–2009 deep solar minimum
Authors: Chen Yiding , Liu Libo , Le Huijun , Wan Weixing
Published: May 2014

In this paper the significant effect of weaker geomagnetic activity during the 2007–2009 deep solar minimum on ionospheric variability on the shorter‐term time scales of several days was highlighted via investigating the response of daily mean global electron content (GEC, the global area integral of total electron content derived from ground‐based GPS measurements) to geomagnetic activity index Ap. Based on a case during the deep solar minimum, the effect of the recurrent weaker geomagnetic disturbances on the ionosphere was evident. Statistical analyses indicate that the effect of weaker geomagnetic activity on GEC variations on shorter‐term time scales was significant during 2007–2009 even under relatively quiet geomagnetic activity condition; daily mean GEC was positively correlated with geomagnetic activity. However, GEC variations on shorter‐term time scales were poorly correlated with geomagnetic activity during the solar cycle descending phase of 2003–2005 except under strong geomagnetic disturbance condition. Statistically, the effects of solar EUV irradiance, geomagnetic activity, and other factors (e.g., meteorological sources) on GEC variations on shorter‐term time scales were basically equivalent during the 2007–2009 solar minimum.
MARSIS observations of the Martian nightside ionosphere dependence on solar wind conditions
Authors: Diéval C. , Morgan D. D. , Němec F. , Gurnett D. A.
Published: May 2014

Despite the absence of solar radiation on the Martian nightside, a weak, irregular, and variable ionosphere is produced there. The nightside ionosphere is thought to be maintained by two main sources: dayside‐nightside plasma transport and electron precipitation. Observations by Mars Express (MEX) and Mars Global Surveyor (MGS) have shown that these plasma sources are either hindered or favored by the presence of strong crustal magnetic fields and that these effects are modulated by external parameters, such as the solar wind dynamic pressure and the orientation of the interplanetary magnetic field (IMF). These external drivers are expected to influence the supply of plasma to the nightside and thus the formation of the irregular nightside ionosphere. We here present a statistical study of the Martian ionosphere at solar zenith angle greater than 107° from November 2005 to May 2006, using remote measurements of ionospheric echoes with the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) radar sounder onboard MEX and using MGS‐based proxies for the solar wind dynamic pressure and the IMF clock angle. We find that the peak densities increase with the dynamic pressure and also that cases of very high peak density are almost always associated with Westward IMF orientation. We find that, using MEX/ASPERA‐3 electron data, these cases often seem to be linked to accelerated electrons. Plasma transport is known to be important in the near nightside. On the other hand, electron precipitation prevails when the dynamic pressure is high enough to compress the ionosphere and in vertical field regions where the IMF orientation matters.
Electric‐Driven Rotation of Silicon Nanowires and Silicon Nanowire Motors
Authors: Xu Xiaobin , Liu Chao , Kim Kwanoh , Fan D. L.
Published: May 2014

In this work, the first highly controllable assembly and rotation of silicon nanowires and nanomotors in suspension are reported. Si and Si composite nanowires are fabricated with precisely controlled dimensions via colloidal assisted catalytic etching. The nanowires can be rotated with deterministic speed and chirality. The rotation speed and orientation not only depend on the applied AC electric frequency, but also on the electronic type, geometry, surface coating, as well as the electric conductance of suspension mediums. Theoretical analysis is used to understand the rotation of Si nanowires, and also the electric resistivity of Si nanowires is determined from their mechanical rotation. The Si nanowires are precisely assembled into nanomotors that can be rotated with controlled speeds and orientations at prescribed locations. This work provides a new paradigm for designing and actuating various Si‐based nanoelectromechanical system (NEMS) devices, which are relevant to man‐made nanomotors, nanorobots, and nanoengines.
Self‐Directed Localization of ZIF‐8 Thin Film Formation by Conversion of ZnO Nanolayers
Authors: Khaletskaya Kira , Turner Stuart , Tu Min , Wannapaiboon Suttipong , Schneemann Andreas , Meyer Robert , Ludwig Alfred , Van Tendeloo Gustaaf , Fischer Roland A.
Published: May 2014

Control of localized metal–organic framework (MOF) thin film formation is a challenge. Zeolitic imidazolate frameworks (ZIFs) are an important sub‐class of MOFs based on transition metals and imidazolate linkers. Continuous coatings of intergrown ZIF crystals require high rates of heterogeneous nucleation. In this work, substrates coated with zinc oxide layers are used, obtained by atomic layer deposition (ALD) or by magnetron sputtering, to provide the Zn2+ ions required for nucleation and localized growth of ZIF‐8 films ([Zn(mim)2]; Hmim = 2‐methylimidazolate). The obtained ZIF‐8 films reveal the expected microporosity, as deduced from methanol adsorption studies using an environmentally controlled quartz crystal microbalance (QCM) and comparison with bulk ZIF‐8 reference data. The concept is transferable to other MOFs, and is applied to the formation of [Al(OH)(1,4‐ndc)]n (ndc = naphtalenedicarboxylate) thin films derived from Al2O3 nanolayers.
Low Temperature Direct of Graphene onto Metal Nano‐Spindt Tip with Applications in Electron Emission
Authors: Koh Angel T. T. , Foong Yuan Mei , Yusop Zamri , Tanemura Masaki , Chua Daniel H. C.
Published: May 2014

Graphene has been known for its superior electronic properties ever since its discovery in 2004. The high aspect ratio and ballistic transport properties exhibited by this one‐dimensional material are especially useful for electron emission applications. However, they are typically grown horizontally and excess efforts, such as the use of transfer techniques, is required to orientate them before effective electron emission from the graphene edges can occur. These transfer techniques have been shown to lead to additional defects to the as‐grown graphene structure, thereby degrading its properties. Here, we present an approach to directly fabricate graphene onto metal nano‐sized spindt tips (or nanocones) using the solid‐state transformation of carbon deposited from a pulsed laser system at low temperature. Besides providing a layer of chemical and mechanical protection for the metal nanocones, the graphene‐on‐metal nanocones gave enhanced emission properties compared to bare metal nanocones. This was due to the reduction of effective field emission tunneling barrier, which was a result of graphene‐metal charge transfer interactions. Controlling the metal nanocones density was also an important factor in determining the field emission performance, as electron screening from neighboring cones should be minimized.
Strain, Bubbles, Dirt, and Folds: A Study of Graphene Polymer‐Assisted Transfer
Authors: Hallam Toby , Berner Nina C. , Yim Chanyoung , Duesberg Georg S.
Published: May 2014

For many applications, in particular in electronics, where chemical vapor deposited (CVD) graphene is used, it needs to be transferred from the growth substrate to the device substrate, generally employing a polymer film as a support layer. This process step is crucial for the overall integrity and electronic performance of the graphene. In this work we will investigate the effects of the transfer using various polymers with atomic force, Raman spectroscopy and X‐ray photoelectron spectroscopy combined with field dependent transport measurements to build up a complete picture regarding the morphology, structural integrity and electrical performance of CVD graphene. Further, we introduce nitrocellulose based polymer alternatives to the most commonly used poly(methyl methacrylate) resist, outperforming the latter in most respects.
A General Approach towards Catechol and Pyrogallol through Ruthenium‐ and Palladium‐Catalyzed CH Hydroxylation by Weak Coordination
Authors: Yang Xinglin , Sun Yonghui , Chen Zhang , Rao Yu
Published: May 2014

An efficient ruthenium(II)‐ and palladium(II)‐catalyzed CH hydroxylation of aryl carbamates has been developed for the facile synthesis of catechols and pyrogallols. The reaction demonstrates excellent reactivity, regio‐ and chemoselectivity, good functional group compatibility and high yields. The practicality of this method has been proved by a gram‐scale synthesis.

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Reactivity of 3‐Substituted Fluorobenzenes in Palladium‐ Catalysed Direct Arylations with Aryl Bromides
Authors: Yan Tao , Zhao Liqin , He Mian , Soulé Jean‐François , Bruneau Christian , Doucet Henri
Published: May 2014

The influence of both electron‐withdrawing and electron‐donating substituents such as nitro, nitrile, chloro, bromo and methoxy at C‐3 on fluorobenzenes for their palladium‐catalysed direct C‐2 arylation has been explored. With electron‐withdrawing substituents, the reaction proceeds nicely using 2–4 mol% of an air‐stable palladium complex and potassium pivalate/dimethylacetamide (PivOK/DMA) as catalytic system; and in general, a very regioselective arylation at C‐2 was observed. Moreover, a variety of substituents on the aryl bromide coupling partner, such as benzoyl, formyl, nitro, nitrile, chloro and methyl, and also heteroaryl bromides were tolerated.

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The Oxidative Annulation of Tertiary Benzyl Alcohols with Internal Alkynes using an (Electron‐Deficient η5‐Cyclopenta‐ dienyl)Rhodium(III) Catalyst under Ambient Conditions
Authors: Fukui Miho , Hoshino Yuki , Satoh Tetsuya , Miura Masahiro , Tanaka Ken
Published: May 2014

It has been established that a dinuclear (electron‐deficient η5‐cyclopentadienyl)rhodium(III) complex catalyzes the oxidative annulation of tertiary benzyl alcohols with internal alkynes via sp2 CH/OH functionalization under ambient conditions (at room temperature under air) to give substituted isochromenes in good yields. The preference for annulation across electron‐rich substrates over electron‐deficient substrates was observed using this electron‐deficient rhodium(III) complex.

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Palladium‐Catalyzed Acyloxylation of 2‐Substituted 1,2,3‐Triazoles via Direct sp2 CH Bond Activation
Authors: Wang Zechao , Kuang Chunxiang
Published: May 2014

The palladium‐catalyzed acyloxylation of 2‐substituted 1,2,3‐triazoles with acids via direct sp2 CH bond activation is described. This reaction is applied to a wide variety of 2‐substituted 1,2,3‐triazoles and exhibits excellent functional group tolerance. The route is found to be efficient for the preparation of 2‐substituted 1,2,3‐triazole derivatives.

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Formal SN‐Type Reactions in Rhodium(III)‐Catalyzed CH Bond Activation
Authors: Kuhl Nadine , Schröder Nils , Glorius Frank
Published: May 2014

(Pentamethylcyclopentadienyl)rhodium (RhCp*)‐catalyzed CH transformations have emerged as a prosperous field in CH bond activation. Recent advances in this area have significantly focused on the development of new strategies for CC and Cheteroatom bond formation that are characterized by the novel reactivity of the RhCp* catalyst to undergo formal SN‐type reactions with electrophilic substrates. This review is intended to give an overview on this rather new class of RhCp*‐catalyzed CH transformations, covering recent CC and Cheteroatom bond‐forming reactions. The nature of the reaction partner in these CH functionalization reactions serves as a guideline throughout this article and, combined with selected descriptions of mechanistic proposals, should emphasize general characteristics of transformations within this novel reaction class.

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Wide spectrum of congenital anomalies including choanal atresia, malformed extremities, and brain and spinal malformations in a girl with a de novo 5.6‐Mb deletion of 13q12.11–13q12.13
Authors: Pavone Piero , Briuglia Silvana , Falsaperla Raffaele , Warm Amiel , Pavone Vito , Bernardini Laura , Novelli Antonio , Praticò Andrea D. , Salpietro Vincenzo , Ruggieri Martino
Published: May 2014

A 2 ½‐year‐old girl with multiple congenital anomalies and a de novo 5.6‐Mb deletion on chromosome 13q12.11–13q12.13 is reported. She showed choanal atresia, scalp aplasia cutis, mild dysmorphic features, severe malformation of the hands and feet, Sylvian aqueductal stenosis, hydrocephalus, small cerebellum with pointed cerebellar tonsils, cervical, lumbar and sacral clefting, single central incisor and mild developmental delay. The girl's anomalies were compared with: (A) one boy reported by each of Der Kaloustian et al. [2011] and Tanteles et al. [2011] with similar, albeit smaller, 2.1 to 2.9 Mb deletions in which the abnormalities consisted of mild facial dysmorphism, mild malformations of the fingers and/or toes, and developmental delay; (B) one girl reported by Friedman et al. [2006] with similar, albeit larger, 5.7 Mb deletion with mild developmental delay and haematological abnormalities; (C) one girl reported by Slee et al. [1991] with a deletion of band q12.2 in chromosome 13, who had Moebius syndrome with facial dysmorphism, high arched palate, micrognathia, and small tongue with no abnormalities of the extremities; and (D) seven additional individuals recorded in the DECIPHER 6.0 database who all had dysmorphic features and developmental delay plus a spectrum of clinical manifestations including deafness, ataxia/oculomotor apraxia, spasticity, small testes, and mild fingers' anomalies. The deleted region hereby reported encompassed 34 known genes, including GJA3, GJB2, and GJB6, which are responsible for autosomal recessive deafness, FGF9, which plays crucial roles in embryonic neurological development, and ATP8A2, which causes a cerebellar ataxia and disequilibrium syndrome. © 2014 Wiley Periodicals, Inc.
Altered DNA methylation status of human brain derived neurotrophis factor gene could be useful as biomarker of depression
Authors: Song Yixuan , Miyaki Koichi , Suzuki Tomoko , Sasaki Yasuharu , Tsutsumi Akizumi , Kawakami Norito , Shimazu Akihito , Takahashi Masaya , Inoue Akiomi , Kan Chiemi , Kurioka Sumiko , Shimbo Takuro
Published: May 2014

Brain‐derived neurotrophic factor (BDNF) is involved in the survival, development, and synaptic plasticity of neurons. BDNF is believed to be associated with the pathophysiology of psychiatric disorders. Several studies have suggested the relevance of DNA methylation in its promoter region with depression. Here, we report different methylation statuses in groups with different depressive scores or undergoing different levels of job‐stress. DNA samples were extracted from the saliva of 774 Japanese workers, and the methylation status was determined using the Illumina HumanMethylation 450 K Microarray. Depressive symptoms were measured using the Kessler's K6 questionnaire. Job‐stress scales were assessed via a self‐administered questionnaire. Independent DNA pools were formed based on K6 and job‐strain scores, and the methylation levels were compared among these pools. The average DNA methylation rate was significantly decreased in the highest K6 score group compared to the lowest group (methylated signals, 14.2% vs. 16.5%, P = 2 · 16 × 10−198). This difference remained for the CpG island in the promoter region (10.4% vs. 5.8%, P = 3 · 67 × 10−133). Regarding the job‐strain score, there was a slight increase in the methylation level of the whole gene in the group with the highest score compared to that with the lowest score; however, these groups showed no difference in the promoter region. Our results revealed significant changes in the DNA methylation status of the complete human BDNF gene in persons with depression compared to normal individuals, especially in the promoter region of exon 1. This indicates that DNA methylation in this gene is a promising biomarker for diagnosing depression. © 2014 The Authors. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics Published by Wiley Periodicals, Inc.
Thermal properties and crystallization behavior of fractionated blocky and random polyhydroxyalkanoate copolymers from mixed microbial cultures
Authors: Laycock Bronwyn , Arcos‐Hernandez Monica V. , Langford Alexandra , Buchanan Jessica , Halley Peter J. , Werker Alan , Lant Paul A. , Pratt Steven
Published: May 2014

This study represents the first detailed analysis of the thermal, morphological, and crystallization properties of the blend components within a range of mixed‐culture polyhydroxyalkanoates (PHAs), with 3‐hydroxyvalerate content in the as‐produced materials and in the fractions ranging from low (12 mol %) to high (91 mol %). Both coarse and fine fractionation of the as‐produced copolymers confirmed that they were blends of nominally blocky and/or random copolymers of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate), with very broad compositional distributions as governed by the PHA accumulation strategy. The crystallization kinetics and thermal properties of the fractions were found to be very significantly different from each other, consistent with the hypothesis that the overall mechanical properties were primarily controlled by the more rapidly crystallizing components. Two materials produced using an alternating feeding strategy demonstrated unique crystallization and thermal properties in their fractions, which are considered to have contributed to distinctly more elastic mechanical properties in these particular samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40836.
Electrospun fibrous membranes for efficient heavy metal removal
Authors: Huang Yunpeng , Miao Yue‐E , Liu Tianxi
Published: May 2014

Heavy metal pollution is a growing environmental problem in recent decades, which requires immediate and urgent action. In this article, we provide an overview of the works published in the last decade concerning the development of electrospinning‐based micro‐ and nano‐porous membranes for efficient heavy metal removal. Apart from their super‐high surface‐to‐volume ratio, electrospun nanofibers possess a variety of surface groups which enable their further functionalization and functional nanoparticle incorporation. Compared to typical adsorbents, electrospun fibrous membranes are superior in many ways like higher permeation flux, lower pressure drop, flexible component adjustment, and even multi‐target adsorption. Therefore, electrospun‐based fibrous membranes hold great potential on the treatment of heavy metal contaminants. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40864.
Toughening of poly(lactic acid) with the renewable bioplastic poly(trimethylene malonate)
Authors: Eyiler Ersan , Chu I‐Wei , Walters Keisha B.
Published: May 2014

The aim of this work was to enhance poly(lactic acid)'s (PLA) flexibility and ductility by blending it with another bioplastic. Poly(trimethylene malonate) (PTM), developed as part of this study, was synthesized from 1,3‐propane diol and malonic acid via melt polycondensation. Blend films of PLA and PTM were prepared by solvent casting from chloroform. Differential scanning calorimetry and thermogravimetric analysis were used to show shifted phase transitions and a single glass‐transition temperature, indicating miscibility of PTM in the blend films. Morphology and mechanical characterizations of the PLA/PTM blend films were performed by atomic force microscopy using a quantitative nanomechanical property mapping mode, tensile testing, and scanning electron microscopy. Miscible blends exhibited Young's modulus and elongation at break values that can significantly extend the usefulness of PLA in commercial applications. The blending of PTM with PLA resulted in films with a 27‐fold increase in toughness compared with neat PLA film. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40888.
Development and evaluation of oil in water nanoemulsions based on polyether silicone as demulsifier and antifoam agents for petroleum
Authors: Fraga Assis K. , Souza Luiz F. I. , Magalhães Jeniffer Rayane , Mansur Claudia R. E.
Published: May 2014

Oil in water (o/w) nanoemulsions were synthesized in order to be evaluated as an alternative to petroleum emulsions destabilization processes and inhibition of foam formed in the crude oil. The nanoemulsions were prepared by the high energy method through High Pressure Homogenizer (HPH), utilizing poly(propylene glycol) (PPG) and xylene solvent as oil phase and different polarity polyether silicone surfactants samples. These nanoemulsions were evaluated in respect to their efficiency in the petroleum demulsification process. The results of these tests showed that nanoemulsions performance on the destabilization of petroleum emulsions is influenced by the utilized surfactant's polarity. The nanoemulsions and pure samples of PPG and xylene solvent were evaluated concerning capacity of formed foam inhibition in petroleum (antifoam test), and the results showed no significant influence of samples on foam stability. Petroleum/saline water added interfacial tension measurements, added or not the nanoemulsions were executed and showed that the additives adsorption in the interface is related to the surfactant's polarity and nanoemulsion drop size. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40889.
Regionalism and Changing Regional Order in the Pacific Islands
Authors: Tarte Sandra
Published: May 2014

Institutional developments in Pacific Islands regionalism have been dramatic in recent years. These include the changing role of the Parties to the Nauru Agreement, a grouping of eight ‘tuna‐rich’ Pacific Island states that is transforming the dynamics of regional fisheries; the emergence of a more activist Melanesian Spearhead Group, which comprises the four largest economies of the Pacific Islands and is leading the process of regional economic integration; and the establishment of the Pacific Islands Development Forum, which promises a more inclusive ‘regionalism through partnerships’ approach in addressing climate change and sustainable development issues. This new dynamism is driven by the discontent of a growing number of island states with the established regional order, defined by prevailing institutions, power and ideas, and by a desire to assert greater control over their own futures. Against the backdrop of an increasingly dynamic geopolitical and geo‐economic landscape, Pacific Island states are using alternative regional frameworks to develop new approaches to the challenges facing them.
A profile‐boosted research analytics framework to recommend journals for manuscripts
Authors: Silva Thushari , Ma Jian , Yang Chen , Liang Haidan
Published: May 2014

With the increasing pressure on researchers to produce scientifically rigorous and relevant research, researchers need to find suitable publication outlets with the highest value and visibility for their manuscripts. Traditional approaches for discovering publication outlets mainly focus on manually matching research relevance in terms of keywords as well as comparing journal qualities, but other research‐relevant information such as social connections, publication rewards, and productivity of authors are largely ignored. To assist in identifying effective publication outlets and to support effective journal recommendations for manuscripts, a three‐dimensional profile‐boosted research analytics framework (RAF) that holistically considers relevance, connectivity, and productivity is proposed. To demonstrate the usability of the proposed framework, a prototype system was implemented using the ScholarMate research social network platform. Evaluation results show that the proposed RAF‐based approach outperforms traditional recommendation techniques that can be applied to journal recommendations in terms of quality and performance. This research is the first attempt to provide an integrated framework for effective recommendation in the context of scientific item recommendation.
Combining lexical and statistical translation evidence for cross‐language information retrieval
Authors: Kim Sungho , Ko Youngjoong , Oard Douglas W.
Published: May 2014

This article explores how best to use lexical and statistical translation evidence together for cross‐language information retrieval (CLIR). Lexical translation evidence is assembled from Wikipedia and from a large machine‐readable dictionary, statistical translation evidence is drawn from parallel corpora, and evidence from co‐occurrence in the document language provides a basis for limiting the adverse effect of translation ambiguity. Coverage statistics for NII Testbeds and Community for Information Access Research (NTCIR) queries confirm that these resources have complementary strengths. Experiments with translation evidence from a small parallel corpus indicate that even rather rough estimates of translation probabilities can yield further improvements over a strong technique for translation weighting based on using Jensen–Shannon divergence as a term‐association measure. Finally, a novel approach to posttranslation query expansion using a random walk over the Wikipedia concept link graph is shown to yield further improvements over alternative techniques for posttranslation query expansion. Evaluation results on the NTCIR‐5 English–Korean test collection show statistically significant improvements over strong baselines.
Trinuclear [CoIII2–LnIII] (Ln=Tb, Dy) Single‐Ion Magnets with Mixed 6‐Chloro‐2‐Hydroxypyridine and Schiff Base Ligands
Authors: Liu Cai‐Ming , Zhang De‐Qing , Hao Xiang , Zhu Dao‐Ben
Published: May 2014

The Schiff base ligand N1,N3‐bis(3‐methoxysalicylidene)diethylenetriamine (H2valdien) and the co‐ligand 6‐chloro‐2‐hydroxypyridine (Hchp) were used to construct two 3d–4f heterometallic single‐ion magnets [Co2Dy(valdien)2(OCH3)2(chp)2]⋅ClO4⋅5 H2O (1) and [Co2Tb(valdien)2(OCH3)2(chp)2]⋅ClO4⋅2 H2O⋅CH3OH (2). The two trinuclear [CoIII2LnIII] complexes behave as a mononuclear LnIII magnetic system because of the presence of two diamagnetic cobalt(III) ions. Complex 1 has a molecular symmetry center, and it crystallizes in the C2/c space group, whereas complex 2 shows a lower molecular symmetry and crystallizes in the P21/c space group. Magnetic investigations indicated that both complexes are field‐induced single‐ion magnets, and the CoIII2–DyIII complex possesses a larger energy barrier [74.1(4.2) K] than the CoIII2–TbIII complex [32.3(2.6) K].
Cooperative Catalysis: Electron‐Rich FeH Complexes and DMAP, a Successful “Joint Venture” for Ultrafast Hydrogen Production
Authors: Rommel Susanne , Hettmanczyk Lara , Klein Johannes E. M. N. , Plietker Bernd
Published: May 2014

A series of defined iron–hydrogen complexes was prepared in a straightforward one‐pot approach. The structure and electronic properties of such complexes were investigated by means of quantum‐chemical analysis. These new complexes were then applied in the dehydrogenative silylation of methanol. The complex (dppp)(CO)(NO)FeH showed a remarkable activity with a TOF of more than 600 000 h−1 of pure hydrogen gas within seconds.
Multiple testing in fMRI: An empirical case study on the balance between sensitivity, specificity, and stability
Authors: Durnez Joke , Roels Sanne P. , Moerkerke Beatrijs
Published: May 2014

Functional Magnetic Resonance Imaging is a widespread technique in cognitive psychology that allows visualizing brain activation. The data analysis encompasses an enormous number of simultaneous statistical tests. Procedures that either control the familywise error rate or the false discovery rate have been applied to these data. These methods are mostly validated in terms of average sensitivity and specificity. However, procedures are not comparable if requirements on their error rates differ. Moreover, less attention has been given to the instability or variability of results. In a simulation study in the context of imaging, we first compare the Bonferroni and Benjamini–Hochberg procedures. Considering Bonferroni as a way to control the expected number of type I errors enables more lenient thresholding compared to familywise error rate control and a direct comparison between both procedures. We point out that while the same balance is obtained between average sensitivity and specificity, the Benjamini–Hochberg procedure appears less stable. Secondly, we have implemented the procedure of Gordon et al. () (originally proposed for gene selection) that includes stability, measured through bootstrapping, in the decision criterion. Simulations indicate that the method attains the same balance between sensitivity and specificity. It improves the stability of Benjamini–Hochberg but does not outperform Bonferroni, making this computationally heavy bootstrap procedure less appealing. Third, we show how stability of thresholding procedures can be assessed using real data. In a dataset on face recognition, we again find that Bonferroni renders more stable results.
A 1,2‐propylene oxide sensor utilizing cataluminescence on CeO2 nanoparticles
Authors: Liu Hongmei , Zhang Yantu , Zhen Yanzhong , Ma Yuan , Zuo Weiwei
Published: May 2014

A simple and sensitive gas sensor was proposed for the determination of 1,2‐propylene oxide (PO) based on its cataluminescence (CTL) by oxidation in the air on the surface of CeO2 nanoparticles. The luminescence characteristics and optimal conditions were investigated in detail. Under optimized conditions, the linear range of the CTL intensity versus the concentration of PO was 10–150 ppm, with a correlation coefficient (r) of 0.9974 and a limit of detection (S/N = 3) of 0.9 ppm. The relative standard deviation for 40 ppm PO was 1.2% (n = 7). There was no or only weak response to common foreign substances including acetone, formaldehyde, ethyl acetate, acetic acid, chloroform, propanol, carbon tetrachloride, ether and methanol. There was no significant change in the catalytic activity of the sensor for 100 h. The proposed method was simple and sensitive, with a potential of detecting PO in the environment and industry. Copyright © 2014 John Wiley & Sons, Ltd.
Applications of micelle enhancement in luminescence‐based analysis
Authors: Alarfaj Nawal A. , El‐Tohamy Maha F.
Published: May 2014

Micelles are self‐assembled aggregates that arrange themselves into spheres in aqueous media. When the surfactant concentration reaches the critical micelle concentration, extensive aggregation of the surfactant monomers occurs to form micelles. A micelle has both a hydrophilic and a hydrophobic part. This allows them to form a spherical shape and for their glycolipid and phospholipid components to form lipid bilayers. The importance of micelles is increasing because of their wide analytical applications. Recently, colloidal carrier systems have received much attention in the field of analytical chemistry, especially in luminescence enhancement applications. Copyright © 2014 John Wiley & Sons, Ltd.
Predicting pneumonia mortality using CURB‐65, PSI, and patient characteristics in patients presenting to the emergency department of a comprehensive cancer center
Authors: Gonzalez Carmen , Johnson Tami , Rolston Kenneth , Merriman Kelly , Warneke Carla , Evans Scott
Published: May 2014

The prognostic accuracy of the CURB‐65 criteria and pneumonia severity index (PSI) in immunocompromised cancer patients with pneumonia is unknown. We sought to determine whether CURB‐65 and PSI predict 28‐day mortality in cancer patients with pneumonia, and identify other factors that predispose cancer patients with pneumonia to a high mortality risk. We assessed sensitivities, specificities, predictive values, and areas under the receiver operating curve area under the curve (AUC) of the CURB‐65 and PSI in predicting the 28‐day mortality of cancer patients presenting to our institution's emergency department with pneumonia. We used the DeLong and Clarke–Pearson approach to determine whether the addition of other risk factors improved the scales' performances. The overall and pneumonia‐related 28‐day mortality rates were 20.2% (n = 44) and 17.4% (n = 38), respectively. In predicting 28‐day mortality, the CURB‐65 score had sensitivity of 45% and specificity of 81%, and the PSI score had sensitivity of 82% and specificity of 34%. The CURB‐65 and PSI discriminated poorly between fatal and nonfatal pneumonia cases (AUCs, 0.664 and 0.658, respectively; 95% confidence interval [CI], 0.57–0.75 for each). The addition of radiation therapy (RT) within 4 weeks and stem cell transplant (SCT) significantly improved the AUCs of the CURB‐65 (0.75; 95% CI, 0.67–0.83) and PSI (0.73; 95% CI, 0.65‐0.82). Inadequate performances of CURB‐65 and PSI demonstrate that a tool for predicting pneumonia‐related mortality in cancer patients and other immunocompromised populations is needed. Pneumonia patients who have undergone recent RT or (SCT) are at a high risk of dying from pneumonia and require special consideration when assessing pneumonia‐related mortality risk.
Induction of dedifferentiated male mouse adipose stromal vascular fraction cells to primordial germ cell‐like cells
Authors: Cui Guanghui , Qi Zhengyu , Zhang Yanmin , Long Xia , Qin Jie , Guo Xin
Published: May 2014

The adipose stromal vascular fraction (SVF) contains abundant mesenchymal stem cell populations that have a limited ability to self‐renew and differentiate. Male mouse adipose SVF cells were dedifferentiated by reprogramming factors (c‐Myc, Oct4, Sox2, and Klf4) to form embryonic stem cell‐like cells (ESCLCs), which upgraded their limited differentiation potential. The ESCLCs were induced to differentiate toward epiblast‐like cells (EpiLCs) and primordial germ cell‐like cells (PGCLCs) by culturing in media supplied with activin A and BMP‐4, respectively. The derived ESCLCs possess embryonic stem cell features and can automatically form embryonic bodies. After culture in EpiLC induction medium for 2–3 days, ESCLCs formed flattened epithelial structures that were different from their original water drop‐like colonies, and the expression of pluripotency‐related genes decreased. When the cells that had been cultured in EpiLC induction medium for 2 days were isolated and cultured in PGCLC induction medium for 4–6 days, they formed typical water drop‐like colonies again. Moreover, expression of the pluripotency‐related genes and the primordial germ cell (PGC) specification‐related genes increased. During progression from ESCLCs toward EpiLCs and PGCLCs, the levels of histone methylases H3K9me2 and H3K27me3 kept changing, which resembled those seen in PGC specification. The derived PGCLCs expressed SSEA‐1, Blimp‐1, and Stella. Furthermore, methylation of Igf2r and Snrpn was retained, but H19 and Kcnq1ot1 methylation levels were slightly reduced compared to non‐PGCLCs, suggesting that the derived PGCLCs may have initiated the process of imprint erasure.
On Ammonia Binding to the Oxygen‐Evolving Complex of Photosystem II: A Quantum Chemical Study
Authors: Schraut Johannes , Kaupp Martin
Published: May 2014

A recent EPR study (M. Perrez Navarro et al., Proc. Natl. Acad. Sci.­ 2013, 110, 15561) provided evidence that ammonia binding to the oxygen‐evolving complex (OEC) of photosystem II in its S2 state takes place at a terminal‐water binding position (W1) on the “dangler” manganese center MnA. This contradicted earlier interpretations of 14N electron‐spin‐echo envelope modulation (ESEEM) and extended X‐ray absorption fine‐structure (EXAFS) data, which were taken to indicate replacement of a bridging oxo ligand by an NH2 unit. Here we have used systematic broken‐symmetry density functional theory calculations on large (ca. 200 atom) model clusters of an extensive variety of substitution patterns and core geometries to examine these contradictory pieces of evidence. Computed relative energies clearly favor the terminal substitution pattern over bridging‐ligand arrangements (by about 20–30 kcal mol−1) and support W1 as the preferred binding site. Computed 14N EPR nuclear‐quadrupole coupling tensors confirm previous assumptions that the appreciable asymmetry may be accounted for by strong, asymmetric hydrogen bonding to the bound terminal NH3 ligand (mainly by Asp61). Indeed, bridging NH2 substitution would lead to exaggerated asymmetries. Although our computed structures confirm that the reported elongation of an Mn–Mn distance by about 0.15 Å inferred from EXAFS experiments may only be reproduced by bridging NH2 substitution, it seems possible that the underlying EXAFS data were skewed by problems due to radiation damage. Overall, the present data clearly support the suggested terminal NH3 coordination at the W1 site. The finding is significant for the proposed mechanistic scenarios of OEC catalysis, as this is not a water substrate site, and effects of this ammonia binding on catalysis thus must be due to more indirect influences on the likely substrate binding site at the O5 bridging‐oxygen position.
Carborane Dyads for Photoinduced Electron Transfer: Photophysical Studies on Carbazole and Phenyl‐o‐carborane Molecular Assemblies
Authors: Kwon Soonnam , Wee Kyung‐Ryang , Cho Yang‐Jin , Kang Sang Ook
Published: May 2014

o‐Carborane‐based donor–acceptor dyads comprising an o‐carboranyl phenyl unit combined with N‐carbazole (1) or 4‐phenyl‐N‐carbazole (2) were prepared, and their dyad characters were confirmed by steady‐state photochemistry and photodynamic experiments as well as electrochemical studies. The absorption and electrochemical properties of the dyads were essentially the sum of those of the carbazole and o‐carboranyl phenyl units; this indicates negligible interaction between the carbazole and o‐carborane units in the ground state. However, the emission spectra of 1 and 2 indicated that carbazole fluorescence was effectively quenched and a new charge‐transfer (CT) emission was observed in solvents, varying from hexane to acetonitrile, which exhibited large Stoke shifts. The CT emission properties of o‐carborane‐based dyads were further analyzed by using Lippert–Mataga plots to show that unit charge separation occurred to form a charge‐separated species in the excited state, namely, 1⋅2. This excited‐state species was confirmed by nanosecond transient absorption spectra and spectroelectrochemical measurements; the photoexcitation of carbazole generated the CT state in which a radical cation and anion were formed at the carbazole and o‐carborane units, respectively, within a few nanoseconds. DFT calculations corroborated the presence of this CT species and showed localized populations of the highest singly occupied molecular orbital on 2 in the reduced anionic state. As a result, molecular assemblies formed by linking the carbazole group with the o‐carborane cage through a phenylene or multi‐phenylene spacer revealed that the photoinduced electron‐transfer process occurred intramolecularly.
Intercalation Study of Low‐Molecular‐Weight Hyperbranched Polyethyleneimine into Graphite Oxide
Authors: Tsoufis Theodoros , Katsaros Fotios , Sideratou Zili , Kooi Bart J. , Karakassides Michael. A. , Siozios Anastasios
Published: May 2014

We report for the first time the intercalation of low‐molecular‐weight hyperbranched polyethyleneimine (PEI) into graphite oxide (GO) for the facile, bulk synthesis of novel graphene‐based hybrid (GO‐PEI) materials exhibiting tailored interlayer galleries. The size of the intercalant as well as the loading in GO were systematically investigated to determine their contribution to the basal spacing of the resulting materials. Powder X‐ray diffraction measurements demonstrated the generation of constrained hybrid systems along the c axis that exhibit considerably increased interlayer distances compared with the starting, pristine GO. The results of X‐ray photoelectron and FTIR studies are consistent with a “grafting‐to” process of the intercalated PEI with the oxygen functional groups present along the GO framework. Furthermore, it was found that a great number of the nitrogen‐containing groups in PEI still remain available within the newly formed, confined micro‐environment of intercalated GO galleries. The increased surface area of the GO‐PEI hybrids in conjunction with the remaining available active groups of intercalated PEI render the synthesised hybrids very attractive candidates as nanostructured adsorbents.
Hierarchically Ordered Self‐Assembly of Amphiphilic Bifullerenes
Authors: Wasserthal Lennard , Schade Boris , Ludwig Kai , Böttcher Christoph , Hirsch Andreas
Published: May 2014

A series of novel functionalised dumbbell‐shaped bifullerenes in which two [5.0] pentakis‐adducts of C60 are covalently connected by cyclic bismalonates were synthesised. These dimeric compounds, carrying various combinations of hydrophilic and hydrophobic addends, self‐assemble in aqueous solution towards supramolecular architectures of different structural complexity as observed by cryogenic transmission electron microscopy (cryo‐TEM). The detailed analysis of the image data revealed an unprecedented hierarchical aggregation behaviour. Whereas completely hydrophilic substituted bifullerenes formed profoundly monodisperse populations of small oligomeric elementary micelles consisting of only three or four bifullerene molecules in a supposedly bent conformation, their amphiphilic equivalents underwent a hierarchical two‐step assembly process towards larger spherical and even rod‐like structures. The data suggest that the hierarchical assembly process is driven by hydrophobic interactions of preformed tetrameric elementary micelles.
Development of a Ruthenium/Phosphite Catalyst System for Domino Hydroformylation–Reduction of Olefins with Carbon Dioxide
Authors: Liu Qiang , Wu Lipeng , Fleischer Ivana , Selent Detlef , Franke Robert , Jackstell Ralf , Beller Matthias
Published: May 2014

Invited for the cover of this issue is the group of Matthias Beller at the Leibniz‐Institut für Katalyse e.V. an der Universität Rostock. The image depicts how ruthenium catalysts can effectively decreases the activation energy to promote the activation of CO2. Read the full text of the article at 10.1002/chem.201400358.
A Multifunctional Magnetic Material under Pressure
Authors: Rodríguez‐Velamazán J. Alberto , Fabelo Oscar , Beavers Christine M. , Natividad Eva , Evangelisti Marco , Roubeau Olivier
Published: May 2014

FeII(Metz)6](FeIIIBr4)2 (Metz=1‐methyltetrazole) is one of the rare systems combining spin‐crossover and long‐range magnetic ordering. A joint neutron and X‐ray diffraction and magnetometry study allows determining its collinear antiferromagnetic structure, and shows an increase of the Néel temperature from 2.4 K at ambient pressure, to 3.9 K at 0.95 GPa. Applied pressure also enables a full high‐spin to low‐spin switch at ambient temperature.
3,3′‐Bi(1,2,4‐oxadiazoles) Featuring the Fluorodinitromethyl and Trinitromethyl Groups
Authors: Kettner Marcos A. , Karaghiosoff Konstantin , Klapötke Thomas M. , Sućeska Muhamed , Wunder Swetlana
Published: May 2014

Here we report on the preparation of two hydrogen atom free 3,3′‐bi(1,2,4‐oxadiazole) derivatives. 5,5′‐Bis(fluorodinitromethyl)‐3,3′‐bi(1,2,4‐oxadiazole) was synthesised by fluorination of diammonium 5,5′‐bis(dinitromethanide)‐3,3′‐bi(1,2,4‐oxadiazole). For our previously reported analogue 5,5′‐bis(trinitromethyl)‐3,3′‐bi(1,2,4‐oxadiazole), a new synthetic route starting from new 3,3′‐bi(1,2,4‐oxadiazolyl)‐5,5′‐diacetic acid was developed. In this course also hitherto unknown 5,5′‐dimethyl‐3,3′‐bi(1,2,4‐oxadiazole) was isolated. The compounds were characterised by multinuclear NMR spectroscopy, IR and Raman spectroscopy, elemental analysis as well as mass spectrometry. X‐ray diffraction studies were performed and the crystal structures for the 5,5'‐dimethyl and 5,5'‐(fluorodinitromethyl) derivatives are reported. The energetic 5,5'‐(fluorodinitromethyl) and 5,5'‐(trinitromethyl) compounds do not contain any hydrogen atoms and show remarkable high densities. Furthermore, the thermal stabilities and sensitivities were determined by differential scanning calorimetry (DSC) and standardised impact and friction tests. The heats of formation were calculated by the atomisation method based on CBS‐4M enthalpies. With these values and the room‐temperature X‐ray densities, several detonation and propulsion parameters, such as the detonation velocity and pressure as well as the specific impulse of mixtures with aluminium, were computed using the EXPLO5 code.
Cross‐Conjugated Hexaphyrins and Their Bis‐Rhodium Complexes
Authors: Naoda Koji , Sung Young Mo , Lim Jong Min , Kim Dongho , Osuka Atsuhiro
Published: May 2014

A cross‐conjugated hexaphyrin that carries two meso‐oxacyclohexadienylidenyl (OCH) groups 9 was synthesized from the condensation of 5,10‐bis(pentafluorophenyl)tripyrrane with 3,5‐di‐tert‐butyl‐4‐hydroxybenzaldehyde. The reduction of 9 with NaBH4 afforded the Möbius aromatic [28]hexaphyrin 10. Bis‐rhodium complex 11, prepared from the reaction of 10 with [{RhCl(CO)2}2], displays strong Hückel antiaromatic character because of the 28 π electrons that occupy the conjugated circuit on the enforced planar structure. The oxidation of 11 with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) yielded complexes 12 and 13 depending upon the reaction conditions. Both 12 and 13 are planar owing to bis‐rhodium metalation. Although complex 12 bears two meso‐OCH groups at the long sides and is quinonoidal and nonaromatic in nature, complex 13 bears 3,5‐di‐tert‐butyl‐4‐hydroxyphenyl and OCH groups and exhibits a moderate diatropic ring current despite its cross‐conjugated electronic circuit. The diatropic ring current increases upon increasing the solvent polarity, most likely due to an increased contribution of an aromatic zwitterionic resonance hybrid.