bluuebunny/crossref_metadata_2025 huggingface dataset:
Increasing AIP Macrocycle Size Reveals Key Features of agr Activation in Staphylococcus aureus
Authors: Johnson Jeffrey G. , Wang Boyuan , Debelouchina Galia T. , Novick Richard P. , Muir Tom W.
Published: March 2015

The agr locus in the commensal human pathogen, Staphylococcus aureus, is a two‐promoter regulon with allelic variability that produces a quorum‐sensing circuit involved in regulating virulence within the bacterium. Secretion of unique autoinducing peptides (AIPs) and detection of their concentrations by AgrC, a transmembrane receptor histidine kinase, coordinates local bacterial population density with global changes in gene expression. The finding that staphylococcal virulence can be inhibited through antagonism of this quorum‐sensing pathway has fueled tremendous interest in understanding the structure–activity relationships underlying the AIP–AgrC interaction. The defining structural feature of the AIP is a 16‐membered, thiolactone‐containing macrocycle. Surprisingly, the importance of ring size on agr activation or inhibition has not been explored. In this study, we address this deficiency through the synthesis and functional analysis of AIP analogues featuring enlarged and reduced macrocycles. Notably, this study is the first to interrogate AIP function by using both established cell‐based reporter gene assays and newly developed in vitro AgrC‐I binding and autophosphorylation activity assays. Based on our data, we present a model for robust agr activation involving a cooperative, three‐points‐of‐contact interaction between the AIP macrocycle and AgrC.
The bigger they are, the harder they fall: A topical review on sedimented solutes for solid‐state NMR
Authors: Ravera Enrico
Published: March 2015

Sample preparation for solid‐state NMR of soluble proteins is all but a trivial accomplishment and often represents the factor that determines the success of the experiments, despite the dramatic methodological and technological improvements in the field of SSNMR. Several different sample preparation have been proposed and applied over the years, with varied results. Among those methods we have proposed the use of sedimentation for obtaining samples with high sensitivity and resolution. This review aims at covering the applications of NMR to sedimented solutes from its first description to the latest developments with implications in the field of DNP. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part A 43A: 209–227, 2015.
Thymol Bromination – A Comparison between Enzymatic and Chemical Catalysis
Authors: Sabuzi Federica , Churakova Ekaterina , Galloni Pierluca , Wever Ron , Hollmann Frank , Floris Barbara , Conte Valeria
Published: March 2015

The catalytic activity of the vanadium‐dependent bromoperoxidase isolated from the brown alga Ascophyllum nodosum is compared with the activity of a cheap, commercially available V‐catalyst precursor in the bromination of thymol. Organic solvents have been avoided to make the system appealing from a sustainable chemistry point of view. It is noteworthy that, notwithstanding the low solubility of the substrate, the thymol bromination reactions were performed in water, with a safe brominating source, under mild conditions, and with relatively inexpensive reagents. In this regard, the greenness of the systems was evaluated by the estimation of the E‐factor value; the result is that the chemical reaction has a lower environmental impact than the enzymatic process, with an E‐factor in the range of eco‐friendly processes.
Interception of Nazarov Reactions of Allenyl Vinyl Ketones with Dienes: (3+2)‐ versus (4+3)‐Cycloaddition and Subsequent Rearrangement
Authors: Morgan Timothy D. R. , LeFort François M. , Li Zhe , Marx Vanessa M. , Boyd Russell J. , Burnell D. Jean
Published: March 2015

Capture of the cyclic oxyallyl cation intermediates from the BF3‐mediated Nazarov reactions of three allenyl vinyl ketones with various dienes was accomplished by (3+2)‐ and (4+3)‐cycloaddition. The relative amounts of these types of products were dependent on the substitution on the diene, and this could be linked to steric hindrance. Treatment of the (3+2)‐cycloaddition products with BF3·Et2O led mainly to decomposition but also to ring‐opened molecules and ring‐enlarged structures. The computed Gibbs energies of the (3+2)‐cycloaddition products, the products of the acid treatment and of some transition states leading to rearranged products were compared.
Synthesis and Characterization of Co3O4/Multiwalled Carbon Nanotubes Nanocomposite for Amperometric Sensing of Hydrazine
Authors: Zhang Jie , Liu Haijing , Dou Meiling , Wang Feng , Liu Jingjun , Li Zhilin , Ji Jing
Published: March 2015

Co3O4 nanoparticles (NPs) were synthesized and decorated on the multi‐walled carbon nanotubes (MWCNTs) through a simple hydrothermal procedure. The deposited Co3O4 NPs on the sidewalls of MWCNTs were found to be cubic crystal structure and homogenously dispersed with a narrow particle size distribution centered at around 6 nm. The Co3O4/MWCNTs nanocomposite was then utilized for the electrochemical detection of hydrazine, and exhibited a high sensitivity of 34.5 µA mM−1, a low detection limit of 0.8 µM (S/N=3), a wide linear range of 20 µM to 1.1 mM along with a short response time of less than 5 s.
Acute‐on‐chronic liver failure precipitated by hepatic injury is distinct from that precipitated by extrahepatic insults
Authors: Shi Yu , Yang Ying , Hu Yaoren , Wu Wei , Yang Qiao , Zheng Min , Zhang Shun , Xu Zhaojun , Wu Yihua , Yan Huadong , Chen Zhi
Published: March 2015

Patients with acute‐on‐chronic liver failure (ACLF) represent a heterogeneous population. The aim of the study is to identify distinct groups according to the etiologies of precipitating events. A total of 405 ACLF patients were identified from 1,361 patients with cirrhosis with acute decompensation and categorized according to the types of acute insults. Clinical characteristics and prognosis between the hepatic group and extrahepatic group were compared, and the performance of prognostic models was tested in different groups. Two distinct groups (hepatic‐ACLF and extrahepatic‐ACLF) were identified among the ACLF population. Hepatic‐ACLF was precipitated by hepatic insults and had relatively well‐compensated cirrhosis with frequent liver and coagulation failure. In contrast, extrahepatic‐ACLF was exclusively precipitated by extrahepatic insults, characterized by more severe underlying cirrhosis and high occurrence of extrahepatic organ failures (kidney, cerebral, circulation, and respiratory systems). Both groups had comparably high short‐term mortality (28‐day transplant‐free mortality: 48.3% vs. 50.7%; P = 0.22); however, the extra‐hepatic‐ACLF group had significantly higher 90‐day and 1‐year mortality (90‐day: 58.9% vs. 68.3%, P = 0.035; 1‐year: 63.9% vs. 74.6%, P = 0.019). In hepatic‐ACLF group, the integrated Model for End‐Stage Liver Disease (iMELD) score had the highest area under the receiver operating characteristic curve (auROC = 0.787) among various prognostic models in predicting 28‐day mortality, whereas CLIF‐Consortium scores for ACLF patients (CLIF‐C‐ACLF) had the highest predictive value in the other group (auROC = 0.779). Conclusions: ACLF precipitated by hepatic insults is distinct from ACLF precipitated by extrahepatic insults in clinical presentation and prognosis. The iMELD score may be a better predictor for hepatic‐ACLF short‐term prognosis, whereas CLIF‐C‐ACLF may be better for extrahepatic‐ACLF patients. (Hepatology 2015;62:232‐242)
One‐Pot Methods for the Protection and Assembly of Sugars
Authors: Zulueta Medel Manuel L. , Janreddy Donala , Hung Shang‐Cheng
Published: March 2015

In recent years, there has been rapid expansion of glycan synthesis, fueled by the recognition that the structural complexity of sugars translates to a myriad of biological functions. Such chemical syntheses involve many challenges, mostly due to the regio‐ and stereochemical aspects of glycosidic bond formation. One‐pot strategies were developed to assist in attaining faster and more economical access to the glycan constructs. In this front, achievements in protecting group manipulation, glycosylation, and combinations of these have been reported. Protecting group manipulations in one pot take advantage of the reaction compatibility of commonly used transformations, many of which occur in high regioselectivity. Sequential glycosylations, on the other hand, rely on leaving group orthogonalities and reactivity tuning, as well as the preactivation technique. Altogether, these approaches offer attractive means to the much needed glycan structures and, consequently, help usher in advances in glycoscience.
The synthesis of new coke‐resistant support and its application in propane dehydrogenation to propene
Authors: Zhou Shijian , Zhou Yuming , Zhang Yiwei , Sheng Xiaoli , Zhang Zewu
Published: March 2015

BACKGROUND

ZSM‐5 zeolite has been used as a common support for PtSn‐based catalyst in the propane dehydrogenation reaction. But owing to its high acidy, coke accommodation and stability of the catalyst are not satisfactory. Here, in order to improve the performance, the new hierarchical‐porous ZSM‐5 (abbreviated henceforth as ZQ) has been synthesized.

RESULTS

By the introduction of hierarchical‐pores in ZQ, the pore structure was changed, the acid content was decreased, and the surface properties were promoted. These modifications to zeolite greatly improved the capacity of catalysts to accommodate coke. Moreover, the coke deposit on PtSnNa/ZQ migrated from active metal to the support. As expected, by using the catalyst PtSnNa/ZQ, the catalytic performance of propane dehydrogenation to propene and the stability of the catalyst were significantly promoted.

CONCLUSIONS

The new hierarchical‐porous ZSM‐5 support (ZQ) exhibits enhanced capacity to accommodate coke, and PtSnNa/ZQ enabled better propane conversion and improved catalyst stability. © 2015 Society of Chemical Industry
The larval head structures of Podagricomela shirahatai (Chûjô) (Chrysomelidae, Galerucinae, Alticini) and morphological effects of leaf mining
Authors: Hua Yi , Beutel Rolf G. , Ge Si‐Qin , Yang Xing‐Ke
Published: March 2015

Cover illustration. The larvae of the leaf beetle species Podagricomela shirahatai are specialized leaf‐miners. In this issue of the Journal of Morphology, Hua et al. (pp. 446–457 10.1002/jmor.20352) present a detailed morphological analysis of the head structures of P. shirahatai and discuss the morphological adaptations to leaf mining in these larvae.
Incorporating Virtual Reactions into a Logic‐based Ligand‐based Virtual Screening Method to Discover New Leads
Authors: Reynolds Christopher R. , Muggleton Stephen H. , Sternberg Michael J. E.
Published: March 2015

The use of virtual screening has become increasingly central to the drug development pipeline, with ligand‐based virtual screening used to screen databases of compounds to predict their bioactivity against a target. These databases can only represent a small fraction of chemical space, and this paper describes a method of exploring synthetic space by applying virtual reactions to promising compounds within a database, and generating focussed libraries of predicted derivatives. A ligand‐based virtual screening tool Investigational Novel Drug Discovery by Example (INDDEx) is used as the basis for a system of virtual reactions. The use of virtual reactions is estimated to open up a potential space of 1.21×1012 potential molecules. A de novo design algorithm known as Partial Logical‐Rule Reactant Selection (PLoRRS) is introduced and incorporated into the INDDEx methodology. PLoRRS uses logical rules from the INDDEx model to select reactants for the de novo generation of potentially active products. The PLoRRS method is found to increase significantly the likelihood of retrieving molecules similar to known actives with a p‐value of 0.016. Case studies demonstrate that the virtual reactions produce molecules highly similar to known actives, including known blockbuster drugs.
Efficient Edge‐swapping heuristics for the reload cost spanning tree problem
Authors: Raghavan S. , Sahin Mustafa
Published: March 2015

The reload cost spanning tree problem (RCSTP) is an NP‐hard problem, where we are given a set of nonnegative pairwise demands between nodes, each edge is colored and a reload cost is incurred when a color change occurs on the path between a pair of demand nodes. The goal is to find a spanning tree with minimum total reload cost. We propose a tree–nontree edge swap neighborhood for the RCSTP and an efficient way to search this neighborhood using preprocessed information. We then embed this edge swap neighborhood within a local search and a tabu search heuristic. We also discuss an initial solution procedure that is used by the local search and tabu search heuristic in a multistart framework. On a test set of 630 instances (that includes benchmark instances from Gamvros et al. [6]), the local search solution improves upon the initial solution in 416 instances by an average of 23.62%, and the tabu search solution improves upon the local search solution in 364 instances by an average of 35.79%. Out of 495 test instances from this set that we know the optimal solutions for, the initial solution is optimal 113 times, the local search solution is optimal 224 times, and the tabu search solution is optimal 481 times. On a second set of benchmark instances from Khalil and Singh [9], the tabu search solution improves upon the best known solution in 32 out of 44 instances. © 2015 Wiley Periodicals, Inc. NETWORKS, Vol. 65(4), 380–394 2015
Improved Ohmic contact to GaN and AlGaN/GaN two‐dimensional electron gas using trap assisted tunneling by B implantation
Authors: Upadhyay Pankaj , Meer Mudassar , Takhar Kuldeep , Khachariya Dolar , Kumar S Akhil , Banerjee Debashree , Ganguly Swaroop , Laha Apurba , Saha Dipankar
Published: March 2015

We have demonstrated that deep level traps created by B implantation can reduce the contact resistance by forming an additional path for electron transport via trap assisted tunneling in GaN and AlGaN/GaN heterostructures. B implantation by plasma‐immersion ion implantation creates deep level traps 0.36 eV below the conduction band edge to a shallow depth (10–25 nm) in the structure. These traps act as efficient percolation path for electrons between the TiN Ohmic contact and the active region, which can be bulk GaN or a two‐dimensional electron gas (2DEG) formed at the AlGaN/GaN heterostructure. The improved Ohmic behavior is manifested as reduced specific contact resistivity and normalized contact resistance. The specific contact resistance and the normalized contact resistance are found to decrease by 59% (30%) and 86% (51%), respectively, for bulk GaN (AlGaN/GaN). The effect of B implantation on the sheet resistance of the 2DEG is insignificant when the implantation energy and post‐implantation annealing time are controlled optimally.
The mammalian blastema: regeneration at our fingertips
Authors: Simkin Jennifer , Sammarco Mimi C. , Dawson Lindsay A. , Schanes Paula P. , Yu Ling , Muneoka Ken
Published: March 2015

In the mouse, digit tip regeneration progresses through a series of discrete stages that include inflammation, histolysis, epidermal closure, blastema formation, and redifferentiation. Recent studies reveal how each regenerative stage influences subsequent stages to establish a blastema that directs the successful regeneration of a complex mammalian structure. The focus of this review is on early events of healing and how an amputation wound transitions into a functional blastema. The stepwise formation of a mammalian blastema is proposed to provide a model for how specific targeted treatments can enhance regenerative performance in humans.
Analysis of cracking in steel fibre‐reinforced concrete (SFRC) structures in bending using probabilistic modelling
Authors: Rossi Pierre , Daviau‐Desnoyers Dominic , Tailhan Jean‐Louis
Published: March 2015

An improvement to the probabilistic discrete cracking model for fibre‐reinforced concretes, originally developed by Rossi, is proposed in this paper.

This new model features the following:

– Crack formation and propagation in the concrete is taken into account by using special interface elements. These elements open once the normal tensile stress at their centre of gravity reaches the tensile strength of the element. The probabilistic aspect of the cracking process is taken into account by the fact that the tensile strength is randomly distributed throughout the mesh elements.

– Immediately after the formation of cracks, the fibre bridging effect is considered by a damage model approach. The probabilistic aspect consists of randomly distributing the post‐cracking energy.

The improved numerical model is used to analyse the bending behaviour of three SFRC beams made from the same material. The numerical simulations are compared with experimental results in terms of the global behaviour of and cracking processes in the beams.
Defects in epoxy‐coated reinforcement and their impact on the service life of a concrete structure
Authors: Keßler Sylvia , Angst Ueli , Zintel Marc , Gehlen Christoph
Published: March 2015

Epoxy‐coated reinforcement (ECR) as a means of protection against chloride‐induced corrosion of steel in concrete is used in only a few countries due to doubts concerning its effectiveness. A common misconception is that possible defects in the coating are particularly weak points as these might favour high local corrosion rates and thus loss of steel cross‐section. This work discusses why a certain number of small defects can be tolerated. It is argued that prolongation of the initiation phase is caused by a higher critical chloride content compared with uncoated steel due to the “size effect”. Additionally, the propagation phase for ECR is likely to be extended due to the severely restricted cathodic area that limits the corrosion rate. This paper presents experimental and numerical tests to verify these assumptions.
Empirical validation of integrated learning performances for hydrologic phenomena: 3rd‐grade students' model‐driven explanation‐construction
Authors: Forbes Cory T. , Zangori Laura , Schwarz Christina V.
Published: March 2015

Water is a crucial topic that spans the K‐12 science curriculum, including the elementary grades. Students should engage in the articulation, negotiation, and revision of model‐based explanations about hydrologic phenomena. However, past research has shown that students, particularly early learners, often struggle to understand hydrologic phenomena and that scientific modeling remains underemphasized in elementary science learning environments. More research is, therefore, needed to understand and promote early learners' engagement in domain‐specific modeling practices. To address this need, we are engaged in design‐based research to foster and investigate 3rd‐grade students' model‐based explanations for the water cycle. Here, we report on the development of a set of empirically based learning performances that integrate core discipline‐specific concepts and the practice of scientific modeling. This framework (i) grounds the iterative adaptation and enhancement of a commonly used curricular unit focused on water and (ii) lays the foundation for ongoing development of an associated learning progression that spans K‐12 grades. Second, we report on findings from research investigating 3rd‐grade students' model‐based explanations within the context of the water cycle. Results illustrate epistemic features of mechanism‐based causal claims elementary students generate and highlight both target concepts and modeling practices emphasized in students' model‐based explanations for hydrologic cycling. © 2015 Wiley Periodicals, Inc. J Res Sci Teach 52: 895–921, 2015.
Exploiting the potential energy landscape to sample free energy
Authors: Ballard Andrew J. , Martiniani Stefano , Stevenson Jacob D. , Somani Sandeep , Wales David J.
Published: March 2015

We review a number of recently developed strategies for enhanced sampling of complex systems based on knowledge of the potential energy landscape. We describe four approaches, replica exchange, Kirkwood sampling, superposition‐enhanced nested sampling, and basin sampling, and show how each of them can exploit information for low‐lying potential energy minima obtained using basin‐hopping global optimization. Characterizing these minima is generally much faster than equilibrium thermodynamic sampling, because large steps in configuration space between local minima can be used without concern for maintaining detailed balance. WIREs Comput Mol Sci 2015, 5:273–289. doi: 10.1002/wcms.1217

This article is categorized under:

Structure and Mechanism > Molecular Structures

Structure and Mechanism > Computational Biochemistry and Biophysics

Structure and Mechanism > Computational Materials Science
Nitrogen‐Rich Alkali Metal Salts (Na and K) of [Bis(N,N‐bis(1H‐tetrazol‐5‐yl)amine)‐zinc(II)] Anion: Syntheses, Crystal Structures, and Energetic Properties
Authors: Li Fugang , Zhao Wenyuan , Chen Sitong , Zhang Tonglai , Zhou Zunning , Yang Li
Published: March 2015

Two nitrogen‐rich alkali metal salts based on nitrogen‐rich anion [Zn(bta)2]2–: {[Na2Zn(bta)2(H2O)8]·H2O}n (1) and {[K2Zn(bta)2(H2O)4]}n (2) were synthesized by reactions of alkali hydroxide, N,N‐bis(1H‐tetrazol‐5‐yl)amine (H2bta), and zinc chloride in aqueous solutions. The crystal structures of 1 and 2 were determined by low temperature single‐crystal X‐ray diffraction and fully characterized by elemental analysis and FT‐IR spectroscopy. The structures demonstrate that an infinite 1‐dimensional (1D) chain structure is constructed by Na+ ions and bridging water molecules in compound 1, which is connected by extensive hydrogen bonds forming a complex 3D network, whereas compound 2 features a more complicated 3D metal‐organic framework (MOF). The thermal behaviors of 1 and 2 were investigated by differential scanning calorimetry (DSC) measurements. The DSC results illustrate that both compounds exhibit high thermal stabilities (decomposition temperature > 345 °C). In addition, the heats of formation were calculated on the basis of the experimental constant‐volume energies of combustion measured by using bomb calorimetry. Lastly, the sensitivities towards impact and friction were assessed according to Bundesamt für Materialforschung (BAM) standard methods.
Preferences, Problems and Representation
Authors: Jennings Will , Wlezien Christopher
Published: March 2015

Scholars studying opinion representation often rely on a survey question that asks about the “most important problem” (MIP) facing the nation. While it is known that MIP responses reflect public priorities, less is known about their connection to policy preferences. This article directly addresses the issue. First, it conceptualizes policy preferences and MIP responses, specifically considering the possibility that the latter may be either policy or outcome based. Second, using aggregate-level data from the United States and the United Kingdom, it then examines the correspondence between public spending preferences and MIP responses over time. The results indicate that MIP responses and spending preferences tap very different things, and that using MIP responses substantially understates the representational relationship between public opinion and policy.
People of Adam: Divine Healing and Racial Cosmopolitanism in the Early Twentieth-Century Transvaal, South Africa
Authors: Cabrita Joel
Published: March 2015

This article analyses the intersection between cosmopolitanism and racist ideologies in the faith healing practices of the Christian Catholic Apostolic Church in Zion. Originally from Illinois, USA, this organization was the period's most influential divine healing group. Black and white members, under the leadership of the charismatic John Alexander Dowie, eschewed medical assistance and proclaimed God's power to heal physical affliction. In affirming the deity's capacity to remake human bodies, church members also insisted that God could refashion biological race into a capacious spiritual ethnicity: a global human race they referred to as the “Adamic” race. Zionist universalist teachings were adopted by dispossessed and newly urbanized Boer ex-farmers in Johannesburg, Transvaal, before spreading to the soldiers of the British regiments recently arrived to fight the Boer states in the war of 1899–1902. Zionism equipped these estranged white “races” with a vocabulary to articulate political reconciliation and a precarious unity. But divine healing was most enthusiastically received among the Transvaal's rural Africans. Amidst the period's hardening segregation, Africans seized upon divine healing's innovative racial teachings, but both Boers and Africans found disappointment amid Zion's cosmopolitan promises. Boers were marginalized within the new racial regimes of the Edwardian empire in South Africa, and white South Africans had always been ambivalent about divine healing's incorporations of black Africans into a unitary race. This early history of Zionism in the Transvaal reveals the constriction of cosmopolitan aspirations amidst fast-narrowing horizons of race, nation, and empire in early twentieth-century South Africa.
ON THE NOTION OF CANONICAL DERIVATIONS FROM OPEN ASSUMPTIONS AND ITS ROLE IN PROOF-THEORETIC SEMANTICS
Authors: FRANCEZ NISSIM
Published: March 2015

The paper proposes an extension of the definition of a canonical proof, central to proof-theoretic semantics, to a definition of a canonical derivation from open assumptions. The impact of the extension on the definition of (reified) proof-theoretic meaning of logical constants is discussed. The extended definition also sheds light on a puzzle regarding the definition of local-completeness of a natural-deduction proof-system, underlying its harmony.
THE RELEVANCE OF PREMISES TO CONCLUSIONS OF CORE PROOFS
Authors: TENNANT NEIL
Published: March 2015

The rules for Core Logic are stated, and various important results about the system are summarized. We describe its relationship to other systems, such as Classical Logic, Intuitionistic Logic, Minimal Logic, and the Anderson–Belnap relevance logicR. A precise, positive explication is offered of what it is for the premises of a proof to connect relevantly with its conclusion. This characterization exploits the notion of positive and negative occurrences of atoms in sentences. It is shown that all Core proofs are relevant in this precisely defined sense. We survey extant results about variable-sharing in rival systems of relevance logic, and find that the variable-sharing conditions established for them are weaker than the one established here for Core Logic (and for its classical extension). Proponents of other systems of relevance logic (such asRand its subsystems) are challenged to formulate a stronger variable-sharing condition, and to prove thatRor any of its subsystems satisfies it, but that Core Logic does not. We give reasons for pessimism about the prospects for meeting this challenge.
Unterrichtsstörungen
Authors: Kostorz Peter
Published: March 2015

Klassenführung und Disziplinmanagement sollen vor allem sicherstellen, dass geplante Lernarrangements möglichst störungsfrei umgesetzt und Lehr-Lern-Prozesse nicht beeinträchtigt werden. Klassenführung bedeutet daher auch immer, Störungen des Unterrichts vorzubeugen und im Bedarfsfall adäquat auf sie zu reagieren. Der vorliegende Beitrag greift diese Aspekte auf und beleuchtet die Bedeutung der Klassenführung für die Prävention von Unterrichtsstörungen und den reaktiven Umgang mit ihnen.
Was ist Kommunikativ-Emanzipatorische (Klassen-)Führung?
Authors: Ragutt Frank
Published: March 2015

Lässt sich eine Lerngruppe demokratisch und zum Zwecke der Humanität führen? Die Pädagogik der Kommunikation gibt Hinweise, wie dies gelingen kann und wie sich der Führungsstil gestaltet.
Klassenführung – früher und heute
Authors: Brosig Klemens M. , Haag Ludwig
Published: March 2015

Kein anderes Merkmal ist so eindeutig mit dem Leistungsniveau einer Klasse verknüpft wie Klassenführung. In vorliegendem Artikel wird die Begriffserweiterung aufgezeigt, die Klassenführung über die Jahre erfahren hat. Mit dieser Perspektive auf die Entwicklung des Begriffes kann schließlich klar herausgearbeitet werden, was heute Klassenführung in der Praxis bedeutet. Überlegungen, wie Klassenführung in der Biographie einer Lehrkraft zu verorten ist, schließen sich an.
Kompetenz-Assessment zur individuellen Lernbegleitung
Authors: Vennewald Nadja , Stumpf-Parketny Tanja
Published: March 2015

Studierende der beruflichen Lehramtsausbildung verfügen oft über unterschiedlich stark ausgeprägte berufsbezogene Kompetenzen. Das Pilotprojekt „Individuelle Lernbegleitung durch Kompetenz-Assessment (ILKA)“ unterstützt Bachelorstudierende an der Fachhochschule Münster gezielt, diese Kompetenzen aktiv zu stärken – Eine Konzeptvorstellung.
Jewell Presents Interior Department's Energy "Reform Agenda"
Authors: Showstack Randy
Published: March 2015

Interior Secretary Jewell says that the agency's agenda includes safe and responsible energy development, good government, and encouraging innovation.
Transfer hydrogenation catalysis in cells as a new approach to anticancer drug design
Authors: Soldevila-Barreda Joan J. , Romero-Canelón Isolda , Habtemariam Abraha , Sadler Peter J.
Published: March 2015

Organometallic complexes are effective hydrogenation catalysts for organic reactions. For example, Noyori-type ruthenium complexes catalyse reduction of ketones by transfer of hydride from formate. Here we show that such catalytic reactions can be achieved in cancer cells, offering a new strategy for the design of safe metal-based anticancer drugs. The activity of ruthenium(II) sulfonamido ethyleneamine complexes towards human ovarian cancer cells is enhanced by up to 50 × in the presence of low non-toxic doses of formate. The extent of conversion of coenzyme NAD+ to NADH in cells is dependent on formate concentration. This novel reductive stress mechanism of cell death does not involve apoptosis or perturbation of mitochondrial membrane potentials. In contrast, iridium cyclopentadienyl catalysts cause cancer cell death by oxidative stress. Organometallic complexes therefore have an extraordinary ability to modulate the redox status of cancer cells.
Enterohemorrhagic Escherichia coli senses low biotin status in the large intestine for colonization and infection
Authors: Yang Bin , Feng Lu , Wang Fang , Wang Lei
Published: March 2015

Enterohemorrhagic Escherichia coli (EHEC) is an important foodborne pathogen that infects humans by colonizing the large intestine. Here we identify a virulence-regulating pathway in which the biotin protein ligase BirA signals to the global regulator Fur, which in turn activates LEE (locus of enterocyte effacement) genes to promote EHEC adherence in the low-biotin large intestine. LEE genes are repressed in the high-biotin small intestine, thus preventing adherence and ensuring selective colonization of the large intestine. The presence of this pathway in all nine EHEC serotypes tested indicates that it is an important evolutionary strategy for EHEC. The pathway is incomplete in closely related small-intestinal enteropathogenic E. coli due to the lack of the Fur response to BirA. Mice fed with a biotin-rich diet show significantly reduced EHEC adherence, indicating that biotin might be useful to prevent EHEC infection in humans.
Magnesiothermic synthesis of sulfur-doped graphene as an efficient metal-free electrocatalyst for oxygen reduction
Authors: Wang Jiacheng , Ma Ruguang , Zhou Zhenzhen , Liu Guanghui , Liu Qian
Published: March 2015

Efficient metal-free electrocatalysts for oxygen reduction reaction (ORR) are highly expected in future low-cost energy systems. We have successfully prepared crumpled, sheet-like, sulfur-doped graphene by magnesiothermic reduction of easily available, low-cost, nontoxic CO2 (in the form of Na2CO3) and Na2SO4 as the carbon and sulfur sources, respectively. At high temperature, Mg can reduce not only carbon in the oxidation state of +4 in CO32− to form graphene, but also sulfur in SO42− from its highest (+6) to lowest valence which was hybridized into the carbon sp2 framework. Various characterization results show that sulfur-doped graphene with only few layers has an appropriate sulfur content, hierarchically robust porous structure, large surface area/pore volume and highly graphitized textures. The S-doped graphene samples exhibit not only a high activity for ORR with a four-electron pathway, but also superior durability and tolerance to MeOH crossover to 40% Pt/C. This is mainly ascribed to the combination of sulfur-related active sites and hierarchical porous textures, facilitating fast diffusion of oxygen molecules and electrolyte to catalytic sites and release of products from the sites.
High Output Piezo/Triboelectric Hybrid Generator
Authors: Jung Woo-Suk , Kang Min-Gyu , Moon Hi Gyu , Baek Seung-Hyub , Yoon Seok-Jin , Wang Zhong-Lin , Kim Sang-Woo , Kang Chong-Yun
Published: March 2015

Recently, piezoelectric and triboelectric energy harvesting devices have been developed to convert mechanical energy into electrical energy. Especially, it is well known that triboelectric nanogenerators have a simple structure and a high output voltage. However, whereas nanostructures improve the output of triboelectric generators, its fabrication process is still complicated and unfavorable in term of the large scale and long-time durability of the device. Here, we demonstrate a hybrid generator which does not use nanostructure but generates much higher output power by a small mechanical force and integrates piezoelectric generator into triboelectric generator, derived from the simultaneous use of piezoelectric and triboelectric mechanisms in one press-and-release cycle. This hybrid generator combines high piezoelectric output current and triboelectric output voltage, which produces peak output voltage of ~370 V, current density of ~12 μA·cm−2 and average power density of ~4.44 mW·cm−2. The output power successfully lit up 600 LED bulbs by the application of a 0.2 N mechanical force and it charged a 10 μF capacitor to 10 V in 25 s. Beyond energy harvesting, this work will provide new opportunities for developing a small, built-in power source in self-powered electronics such as mobile electronics.
Elevated levels of perfluoroalkyl acids in family members of occupationally exposed workers: the importance of dust transfer
Authors: Fu Jianjie , Gao Yan , Wang Thanh , Liang Yong , Zhang Aiqian , Wang Yawei , Jiang Guibin
Published: March 2015

The exposure pathways of perfluoroalkyl acids (PFAAs) to humans are still not clear because of the complex living environment and few studies have simultaneously investigated the bioaccumulative behaviour of different PFAAs in humans. In this study, serum, dust, duplicate diet and other matrices were collected around a manufacturing plant in China and homologous series of PFAAs were analysed. PFAA levels in dust and serum of local residents in this area were considerably higher than those in non-polluted area. Although dietary intake was the major exposure pathway in the present study, dust ingestion played an important role in this case. Serum PFAAs in local residents was significantly correlated with dust PFAAs levels in their living or working microenvironment. Serum PFAAs and dust PFAAs were significantly higher in family members of occupational workers (FM) than in ordinary residents (OR) (p < 0.01). After a careful analysis of the PFAAs exposure pathway, a potential pathway in addition to direct dust ingestion was suggested: PFAAs might transferred from occupational worker's clothes to dinners via cooking processes. The bioaccumulative potential of PFHxS and PFOS were higher than other PFAAs, which suggested a substantial difference between the bioaccumulative ability of perfluorinated sulfonic acids and perfluorinated carboxylic acids.
Generation mechanism of hydroxyl radical species and its lifetime prediction during the plasma-initiated ultraviolet (UV) photolysis
Authors: Attri Pankaj , Kim Yong Hee , Park Dae Hoon , Park Ji Hoon , Hong Young J. , Uhm Han Sup , Kim Kyoung-Nam , Fridman Alexander , Choi Eun Ha
Published: March 2015

Through this work, we have elucidated the mechanism of hydroxyl radicals (OH•) generation and its life time measurements in biosolution. We observed that plasma-initiated ultraviolet (UV) photolysis were responsible for the continues generation of OH• species, that resulted in OH• to be major reactive species (RS) in the solution. The density and lifetime of OH• species acted inversely proportional to each other with increasing depth inside the solution. The cause of increased lifetime of OH• inside the solution is predicted using theoretical and semiempirical calculations. Further, to predict the mechanism of conversion of hydroxide ion (OH−) to OH• or H2O2 (hydrogen peroxide) and electron, we determined the current inside the solution of different pH. Additionally, we have investigated the critical criterion for OH• interaction on cancer cell inducing apoptosis under effective OH• exposure time. These studies are innovative in the field of plasma chemistry and medicine.
Perinatal outcomes of maternal overweight and obesity in term infants: a population-based cohort study in Canada
Authors: Vinturache Angela Elena , McDonald Sheila , Slater Donna , Tough Suzanne
Published: March 2015

The objective of this study was to assess the impact of increased pre-pregnancy maternal body mass index (BMI) on perinatal outcomes in term, singleton pregnancies who received prenatal care in community-based practices. The sample of 1996 infants included in the study was drawn from the All Our Babies Study, a prospective pregnancy cohort from Calgary. Multivariable logistic regression explored the relationship between the main outcomes, infant birth weight, Apgar score, admission to neonatal intensive care (NICU) and newborn duration of hospitalization and BMI prior to pregnancy. Approximately 10% of the infants were macrosoms, 1.5% had a low Apgar score (<7 at 5 min), 6% were admitted to intensive care and 96% were discharged within 48 h after delivery. Although the infants of overweight and obese women were more likely to have increased birth weight as compared to infants of normal weight women, there were no differences in Apgar score, admission to NICU, or length of postnatal hospital stay among groups. This study suggests that in otherwise healthy term, singleton pregnancies, obesity does not seem to increase the risk of severe fetal impairment, neonatal admission to intensive care or duration of postnatal hospitalization.
Exploring hydrogen peroxide responsive thiazolidinone-based prodrugs
Authors: Perez Christian , Monserrat Jean-Philippe , Chen Yao , Cohen Seth M.
Published: March 2015

A thiazolidinone moiety was found to serve as a protecting group for releasing carboxylic acid-containing therapeutics in the presence of hydrogen peroxide.
Recent advances in dialkyl carbonates synthesis and applications
Authors: Huang Shouying , Yan Bing , Wang Shengping , Ma Xinbin
Published: March 2015

This review describes the recent advances in the synthesis and applications of dialkyl carbonates, particularly focusing on the catalyst rational design, catalytic mechanism, and process intensification in the CO and CO2routes.
Insulin glycation coupled with liposomal lipid peroxidation and microglial cell death
Authors: Sabokdast Manijheh , Habibi-Rezaei Mehran , Poursasan Najmeh , Sabouni Farzaneh , Ferdousi Maryam , Azimzadeh-Irani Effat , Moosavi-Movahedi Ali Akbar
Published: March 2015

Type 2 diabetes is characterized jointly by hyperglycemia and hyperinsulinemia, which make insulin prone to glycation then fibrillation.
Four related mixed-ligand nickel(ii) complexes: effect of steric encumbrance on the structure, DNA/BSA binding, DNA cleavage and cytotoxicity
Authors: Gao Chun-Yan , Ma Zhong-Ying , Zhang Yong-Po , Li Si-Tong , Gu Wen , Liu Xin , Tian Jin-Lei , Xu Jing-Yuan , Zhao Jin-Zhong , Yan Shi-Ping
Published: March 2015

Four new interrelated mixed-ligand nickel(ii) complexes have been synthesized and characterized. The activities of DNA binding/cleavage, BSA binding with complexes and the vitro cytotoxicity also have been explored.
Interplay of particle shape and suspension properties: a study of cube-like particles
Authors: Audus Debra J. , Hassan Ahmed M. , Garboczi Edward J. , Douglas Jack F.
Published: March 2015

The dilute suspension properties, including the intrinsic viscosity, intrinsic solvent diffusivity, intrinsic conductivities of perfect conductors and perfect insulators, for a family of particles that smoothly interpolate between spheres and cubes were determined using three different simulation techniques in order to explore the role of particle shape.
High temperature superconducting materials as bi-functional catalysts for hydrogen evolution and oxygen reduction
Authors: Lim Chee Shan , Wang Lu , Chua Chun Kiang , Sofer Zdeněk , Jankovský Ondřej , Pumera Martin
Published: March 2015

This work seeks to investigate the feasibility of two high-temperature superconductors, YBCO and BSCCO in catalysing the hydrogen evolution and oxygen reduction reactions electrochemically.
A general catalytic reaction sequence to access alkaloid-inspired indole polycycles
Authors: Danda Adithi , Kumar Kamal , Waldmann Herbert
Published: March 2015

A general two-step catalytic reaction sequence affording a range of indole alkaloid-inspired complex molecular frameworks is presented.
Reversible and contrasting changes of the cloud point temperature of pillar[5]arenes with one quinone unit and tri(ethylene oxide) chains induced by redox chemistry and host–guest complexation
Authors: Ogoshi Tomoki , Akutsu Tomohiro , Tamura Yuko , Yamagishi Tada-aki
Published: March 2015

A new water-soluble redox-active pillar[5]arene was synthesized by incorporation of one benzoquinone unit.
Flavylium based dual photochromism: addressing cis–trans isomerization and ring opening-closure by different light inputs
Authors: Gago Sandra , Basílio Nuno , Moro Artur J. , Pina Fernando
Published: March 2015

A multistate system of 4′,7-dihydroxy-3-methoxyflavylium: two interconnected photochromic systems based on cis–trans isomerization and ring opening-closure are independently addressable at different wavelengths.
Photocatalytic overall water splitting on the perovskite-type transition metal oxynitride CaTaO2N under visible light irradiation
Authors: Xu Jiasheng , Pan Chengsi , Takata Tsuyoshi , Domen Kazunari
Published: March 2015

Photocatalytic overall water splitting was achieved on a simple perovskite-type oxynitride CaTaO2N (B.G. = 2.43 eV) after the proper surface modification.
Efficient charge separation on 3D architectures of TiO2 mesocrystals packed with a chemically exfoliated MoS2 shell in synergetic hydrogen evolution
Authors: Zhang Peng , Tachikawa Takashi , Fujitsuka Mamoru , Majima Tetsuro
Published: March 2015

With anisotropic electron flow and charge separation, TiO2 mesocrystals packed with a chemically exfoliated MoS2 shell exhibit efficient hydrogen evolution compared to nanocrystals.
X-ray crystallography-promoted drug design of carbonic anhydrase inhibitors
Authors: Ivanova Jekaterina , Leitans Janis , Tanc Muhammet , Kazaks Andris , Zalubovskis Raivis , Supuran Claudiu T. , Tars Kaspars
Published: March 2015

The X-ray co-crystallization experiments of saccharin derivative with carbonic anhydrase revealed hydrolysis of isothiazole ring of saccharin and guided design of new inhibitors.
Direct observation of enhanced plasmon-driven catalytic reaction activity of Au nanoparticles supported on reduced graphene oxides by SERS
Authors: Liang Xiu , You Tingting , Liu Dapeng , Lang Xiufeng , Tan Enzhong , Shi Jihua , Yin Penggang , Guo Lin
Published: March 2015

Compared with Au NPs, Au/rGO exhibited an enhanced catalytic activity in the reduction from 4-nitrobenzenethiol (4-NBT) to p,p′-dimercaptoazobenzene (DMAB) during systematic SERS experiments.
Atomic collisions in suprafluid helium-nanodroplets: timescales for metal-cluster formation derived from He-density functional theory
Authors: Hauser Andreas W. , Volk Alexander , Thaler Philipp , Ernst Wolfgang E.
Published: March 2015

Two copper atoms, collected in a pickup-process by a He droplet consisting of 5000 atoms, move along rosetta-like, planar trajectories until the inter-particle attraction makes them collide.
Heteroleptic naphthalo-phthalocyaninates of lutetium: synthesis and spectral and conductivity properties
Authors: Dubinina Tatiana V. , Kosov Anton D. , Petrusevich Elizaveta F. , Maklakov Sergey S. , Borisova Nataliya E. , Tomilova Larisa G. , Zefirov Nikolay S.
Published: March 2015

A series of novel near-IR absorbing heteroleptic complexes were obtained with high yields. The correlation between the nature of the substituents and spectral properties of the target complexes was determined.
Synthesis and characterization of mixed-valence manganese fluorophosphate and analogues with clathrate-like structures: MnIII6F12(PO3(OH))8[Na8(Kx(H3O)4−x(H2O)2)MIV(OH)6] (MIV = Mn, Ti, Ge)
Authors: Ren Wei-Jian , Wang Jing-Quan , Huang Ya-Xi , Sun Zhi-Mei , Pan Yuanming , Mi Jin-Xiao
Published: March 2015

A water-deficient hydrothermal method has been applied to synthesize the first-ever, mixed- and high-valence manganese (Mn3+/Mn4+) fluorophosphate with a clathrate-like structure.
Hierarchical LiZnVO4@C nanostructures with enhanced cycling stability for lithium-ion batteries
Authors: Zeng Lingxing , Huang Xiaoxia , Zheng Cheng , Qian Qingrong , Chen Qinghua , Wei Mingdeng
Published: March 2015

Hierarchical LiZnVO4@C nanostructures composed of thin nanobelt aggregates were synthesized for the first time and they exhibited a high performance for LIBs.
Ascorbic acid decomposition into oxalate ions: a simple synthetic route towards oxalato-bridged heterometallic 3d–4f clusters
Authors: Dinca Alina S. , Shova Sergiu , Ion Adrian E. , Maxim Catalin , Lloret Francesc , Julve Miguel , Andruh Marius
Published: March 2015

Dodecanuclear and hexanuclear heterometallic 3d–4f clusters have been obtained by connecting the lanthanide ions through oxalato bridges arising from the slow decomposition of the l-ascorbic acid.
Enhancing the electronic properties and quantum efficiency of sulfonyl/phosphoryl-substituted blue iridium complexes via different ancillary ligands
Authors: Si Yanling , Zhang Shuai , Qu Nan , Luan Guoyou , Wu Zhijian
Published: March 2015

The influence of the ancillary ligands for iridium complexes on the electronic structures, absorption and emission spectra, and quantum efficiency was investigated. The results reveal that they not only tune the energy gap but also enhance the quantum efficiency.
Stereoselective synthesis of (all-Z)-hentriaconta-3,6,9,12,15,19,22,25,28-nonaene
Authors: Filippova Liudmila , Aarum Ida , Ringdal Martine , Dahl Martin Kirkhus , Hansen Trond Vidar , Stenstrøm Yngve
Published: March 2015

EPA-EE was converted in eight steps and 15% overall yield to the natural product (all-Z)-hentriaconta-3,6,9,12,15,19,22,25,28-nonaene. The synthesis confirms the all-Z-configuration of all nine double bonds.
‘Blocky’ donor–acceptor polymers containing selenophene, benzodithiophene and thienothiophene for improved molecular ordering
Authors: Gao Dong , Gibson Gregory L. , Hollinger Jon , Li Pengfei , Seferos Dwight S.
Published: March 2015

A straightforward synthetic route to blocky D–A copolymers consisting of selenophene, benzodithiophene, and thienothiophene is reported.
Organic solar cells based on bowl-shaped small-molecules
Authors: Molina-Ontoria Agustín , Gallego María , Echegoyen Luís , Pérez Emilio M. , Martín Nazario
Published: March 2015

A supramolecular approach involving bowl-shape molecules as electron donors has been used for the preparation of small-molecule solar cells. The PCE values depend directly on the formation of the supramolecular complex.
New insights into reinforcement mechanism of nanoclay-filled isoprene rubber during uniaxial deformation by in situ synchrotron X-ray diffraction
Authors: Fu Xuan , Huang Guangsu , Xie Zhengtian , Xing Wang
Published: March 2015

The existence of a denser network domain formed by incorporation of filler and its vital role in determining the strain-induced crystallization behavior of nanocomposites is proved by in situ synchrotron X-ray diffraction characterization.