bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of Diastereomeric Bicyclo[3.3.1]nonane Dibenzoyl Esters and Study of Their Chiroptical Properties
Authors: Bagdžiūnas G. , Butkus E. , Stončius S. 
Published: July 2012

ABSTRACTA synthesis of diastereomeric bicyclic dibenzoyl esters derived from enantiomerically pure (1S,5S)‐bicyclo[3.3.1]nonane‐2,6‐dione was accomplished. Molecules containing two benzoyl chromophores with different configuration in the bicyclic framework were obtained. Chiroptical properties of the synthesized enantiomerically pure molecules were studied. Diastereomeric esters exhibited exciton couplets in the circular dichroism (CD) spectra because of transannular interaction between non‐conjugated benzoate chromophores. The conformational effects and solvent impact on the exciton coupling were examined by CD spectroscopy. Theoretical computation of the CD spectra of diastereomers correctly reproduced the sign of the exciton couplets in the studied molecules, however, no major solvent dielectric constant influence and conformational effects per se on the exciton coupling was observed. Chirality 24:810–816, 2012. © 2012 Wiley Periodicals, Inc.
Experimental Investigation on the Use of Wire Mesh Inserts and Structured Tubes in Thermosyphon Reboilers
Authors: Hammerschmidt Jochen , Scholl Stephan 
Published: July 2012

AbstractEs werden experimentelle Untersuchungen zum Einsatz von Turbulenzpromotoren in Naturumlaufverdampfern vorgestellt. An einem Einrohr‐Naturumlaufverdampfer wurde das fluiddynamische und wärmetechnische Verhalten bei der Verdampfung von Wasser sowie eines Wasser/Glycerin‐Gemisches untersucht. Bei der Verdampfung von Wasser wurde insbesondere mit dem innenberippten Rohr eine Stabilisierung der Fluiddynamik und deutliche Erhöhung des Wärmeübergangs festgestellt. Für das Wasser/Glycerin‐Gemisch zeigte das Drahtgestrick‐Insert die besten Ergebnisse.
Complex Formation of d‐Metal Ions at the Interface of TbIII‐Doped Silica Nanoparticles as a Basis of Substrate‐Responsive TbIII‐Centered Luminescence
Authors: Davydov Nikolay , Mustafina Asiya , Burilov Vladimir , Zvereva Elena , Katsyuba Sergey , Vagapova Liliya , Konovalov Alexander , Antipin Igor 
Published: July 2012

AbstractThe complex formation of d‐metal ions at the interface of TbIII‐doped silica nanoparticles modified by amino groups is introduced as a route to sensing d‐metal ions and some organic molecules. Diverse modes of surface modification (covalent and noncovalent) are used to fix amino groups onto the silica surface. The interfacial binding of d‐metal ions and complexes is the reason for the TbIII‐centered luminescence quenching. The regularities and mechanisms of quenching are estimated for the series of d‐metal ions and their complexes with chelating ligands. The obtained results reveal the interfacial binding of CuII ions as the basis of their quantitative determination in the concentration range 0.1–2.5 μM by means of steady‐state and time‐resolved fluorescence measurements. The variation of chelating ligands results in a significant effect on the quenching regularities due to diverse binding modes (inner or outer sphere) between amino groups at the interface of nanoparticles and FeIII ions. The applicability of the steady‐state and time‐resolved fluorescence measurements to sense both FeIII ions and catechols in aqueous solution by means of TbIII‐doped silica nanoparticles is also introduced.
Nanocomposites of Ni(OH)2/Reduced Graphene Oxides with Controllable Composition, Size, and Morphology: Performance Variations as Pseudocapacitor Electrodes
Authors: Xiao Junwu , Yang Shihe 
Published: July 2012

AbstractAlthough Ni(OH)2 is a promising electrode material for electrochemical capacitors on account of its high theoretical specific capacitance and low cost, its application has been hindered by the low measured specific capacitance and poor cycle stability often associated with low specific surface area and poor electrical conductivity. This study aims to develop an amorphous‐precursor method to anchor Ni(OH)2 nanocrystals onto conductive graphene sheets. We demonstrate the ability to control the composition, size, and morphology of Ni(OH)2 nanocrystals on graphene sheets by combination with an Ostwald ripening process, which has allowed investigation on how such factors influence their performance if used as pseudocapacitor electrodes. It was found that the specific capacitance increased and then decreased as the ratio of reduced graphene oxide (RGO) to Ni(OH)2 increased; the sample that contained 5.2 wt % of RGO achieved the highest specific capacitance of 1804.0 F g−1 (based on the total composite mass) and 1902.9 F g−1 (based on the mass of Ni(OH)2), close to the theoretical value of Ni(OH)2 (2082 F g−1). With a given ratio of RGO to Ni(OH)2, the specific capacitance decreased as the Ni(OH)2 nanocrystal size increased. However, the cycling performance increased as the stability of Ni(OH)2 in the nanocomposites increased; the highest was achieved for the most stable Ni(OH)2 hexagonal nanoplates on RGO. In all, with appropriate optimization of the parameters of the materials, a good pseudocapacitor performance was achieved for the Ni(OH)2/RGO hybrid system in terms of both the specific capacitance and the cycling stability.
Controllable synthesis of hierarchical strontium molybdate by sonochemical method
Authors: Jiang Wanquan , Zhu Wei , Peng Chao , Yang Fan , Xuan Shouhu , Gong Xinglong 
Published: July 2012

AbstractLarge‐scale chrysanthemum‐like strontium molybdate (SrMoO4) with hierarchical structure has been successfully synthesized via a facile and fast ultrasound irradiation approach at room temperature. By varying the experimental conditions, SrMoO4 with different morphologies, such as spindles, peanuts, spheres, and rods, can be obtained. The products are characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected‐area electron diffraction (SAED). The influent parameters including concentration, pH value, and surfactants have been investigated. A possible growth mechanism is proposed and the shape evolution of the products is characterized. The as‐prepared chrysanthemum‐like SrMoO4 particles are used as the precursor for electrorheological fluid and their electrorheological property is investigated.
A new tool for conditional gene manipulation in a subset of keratin‐expressing epithelia
Authors: Wang Yinqiu , Guo Qiusha , Casey Adam , Lin Congxing , Chen Feng 
Published: July 2012

AbstractMegsin is a serine protease inhibitor (Serpin) that has known expression in kidney mesangial cells. Here, we report the generation and characterization of a bacterial artificial chromosome (BAC) transgene expressing Cre under the control of Megsin regulatory elements. When crossed to the ROSA26R‐lacZ reporter mice, the Megsin‐Cre transgene mediates loxP recombination primarily in the skin, forestomach, and esophagus, but surprisingly not in the mesangial cells. Within the skin, cells in all epidermal layers and the hair follicle cells expressed Cre. This transgene also has uniform expression in the epithelium of the forestomach and esophagus. Conditional deletion of Adam10, a gene known to have important functions in skin development, by using this Megsin‐Cre transgene led to severe skin defects. In addition, these mutants appear to have reduced folds and surface area in the forestomach. These results show that the Megsin‐Cre transgene can mediate loxP‐recombination in all epidermal layers of the skin, the hair follicle cells, as well as in the epithelium of the forestomach and esophagus, all of which have known expression of various keratins. This Megsin‐Cre transgene can serve as a new tool for conditional genetic manipulation to study development and diseases in the skin and the upper digestive tract. genesis 50:899–907, 2012. © 2012 Wiley Periodicals, Inc.
Atypical reproductive cycles in a population of Sceloporus grammicus (Squamata: Phrynosomatidae) from the Mexican Plateau
Authors: Ramírez‐Bautista Aurelio , Stephenson Barry P. , Lozano Abraham , Uribe‐Rodríguez Héctor , Leyte Manrique Adrian 
Published: July 2012

AbstractThe spiny lizard Sceloporus grammicus (Squamata: Phrynosomatidae) is a small reptile from central México and the southern United States, occurring in a wide geographic area characterized by extensive variation in topographic and climatic regimes. Genetic variation among lineages from central México is substantial, though the extent to which this variation corresponds with life‐history traits remains obscure. To address part of this puzzle, we studied a population of S. grammicus from Tepeapulco, Hidalgo, México. Male‐biased sexual dimorphism was extensive in this population; males were larger than females overall, and expressed proportionately larger heads and longer limbs. Minimum size at sexual maturity was similar in the sexes (males: 43 mm; females: 42 mm). In contrast to other populations from the Central Plateau, reproductive activity of males and females was synchronous. Testicular recrudescence of adult males was initiated in October–November, and maximum testis size maintained from December to July. Female reproductive activity showed no clear seasonal pattern: females had vitellogenic follicles from October to July, and pregnant females were found throughout the year. Female body size was not related to litter size. Neither male nor female gonadal mass was correlated with any abiotic environmental variable examined. Differences in reproductive characteristics among populations of S. grammicus might be indicative of plasticity in response to local environmental conditions, local adaptation, or complex gene × environment interactions. We consider these results in the context of previously studied populations of S. grammicus from the Central Plateau and elsewhere, and propose directions for future research.
Evidence of a strong coupling between root exudation, C and N availability, and stimulated SOM decomposition caused by rhizosphere priming effects
Authors: Bengtson Per , Barker Jason , Grayston Sue J. 
Published: July 2012

AbstractIncreased temperatures and concomitant changes in vegetation patterns are expected to dramatically alter the functioning of northern ecosystems over the next few decades. Predicting the ecosystem response to such a shift in climate and vegetation is complicated by the lack of knowledge about the links between aboveground biota and belowground process rates. Current models suggest that increasing temperatures and rising concentrations of atmospheric CO
2 will be partly mitigated by elevated C sequestration in plant biomass and soil. However, empirical evidence does not always support this assumption, as elevated temperature and CO
2 concentrations also accelerate the belowground C flux, in many cases extending to increased decomposition of soil organic matter (SOM) and ultimately resulting in decreased soil C stocks. The mechanism behind the increase has remained largely unknown, but it has been suggested that priming might be the causative agent. Here, we provide quantitative evidence of a strong coupling between root exudation, SOM decomposition, and release of plant available N caused by rhizosphere priming effects. As plants tend to increase belowground C allocation with increased temperatures and CO
2 concentrations, priming effects need to be considered in our long‐term analysis of soil C budgets in a changing environment. The extent of priming seems to be intimately linked to resource availability, as shifts in the stoichiometric nutrient demands of plants and microorganisms will lead to either cooperation (resulting in priming) or competition (no priming will occur). The findings lead us on the way to resolve the varying response of primary production, SOM decomposition, and release of plant available N to elevated temperatures, CO
2 concentrations, and N availability.
Intra‐annual variability and environmental controls over transpiration in a 58‐year‐old even‐aged stand of invasive woodyJuniperus virginianaL. in the Nebraska Sandhills, USA
Authors: Awada Tala , El‐Hage Rita , Geha Makram , Wedin David A. , Huddle Julie A. , Zhou Xinhua , Msanne Joseph , Sudmeyer Robert A. , Martin Derrel L. , Brandle James R. 
Published: July 2012

ABSTRACTWe investigated the intra‐annual variability and environmental controls over transpiration (E) in a planted, even‐aged (58 years; 537 trees ha−1), experimental forest of invasive nativeJuniperus virginianain the Nebraska Sandhills, with three canopy classes (dominant, co‐dominant, and suppressed) by using sap flux techniques, in a year where drought was absent (2008, 34% above average precipitation). DailyEwas closely linked to growing‐season length and variability in the environment. Minimum and average daily air temperatures, photosynthetically active radiation, and precipitation explained the majority of the intra‐annual daily variability inE. Vapour pressure deficit was a significant factor in spring and summer, shallow volumetric soil water content (VSWC 0·2 m) was important during summer particularly June, and deep VSWC (0·6 m) was a significant factor in January and August.Ewas highest in the dominant trees and contributed to the majority (~77%) of stand transpiration (Ec) on site because of their larger canopy size, greater tree density, more leaf area, and accessibility to water resources compared with the co‐dominant and suppressed tree canopies, which contributed to 16% and 7%, respectively.Ecaveraged ~413 mm year−1, corresponding to ~24% of potential evapotranspiration. Soils were significantly drier in theJ. virginianastand than in adjacent C4‐dominated grasslands, which could be due to the longer growing season over which physiological activity extends inJ. virginianacompared with C4‐dominated grasslands in the region and precipitation interception by the canopy and forest floor, which evaporates before reaching the soil. Copyright © 2012 John Wiley & Sons, Ltd.
Tellurium–Nitrogen π‐Heterocyclic Chemistry – Synthesis, Structure, and Reactivity Toward Halides and Pyridine of 3,4‐Dicyano‐1,2,5‐telluradiazole
Authors: Semenov Nikolay A. , Pushkarevsky Nikolay A. , Beckmann Jens , Finke Pamela , Lork Enno , Mews Rüdiger , Bagryanskaya Irina Yu. , Gatilov Yuri V. , Konchenko Sergey N. , Vasiliev Vladimir G. , Zibarev Andrey V. 
Published: July 2012

AbstractThe reaction of 2,3‐diaminomaleonitrile with TeX4(X = Cl, Br) in the presence of pyridine (Py) and/or triethylamine (Et3N) provided 3,4‐dicyano‐1,2,5‐telluradiazole (1), which was isolated neat and as stable adducts with pyridine, chloride, and bromide, namely,1·2Py, (PyH)(1·Cl), (PyH)2(1·2Cl), (Et3NH)(1·Cl), (PyH)(1·Br), and (PyH)2(1·2Br). The molecular and supramolecular structures of these compounds were investigated by X‐ray crystallography. In the solid state, intermolecular associations through secondary Te···N interactions as well as N–H···X and N–H···N hydrogen bonding (X = Cl, Br) were observed. For (PyH)(1·Br), two polymorphs were found. The bonding situation of1and its pyridine and chloride adducts were investigated by MP2 calculations supplemented with the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. The π symmetry of the frontier molecular orbitals (MOs) of1are preserved in the1·2Py, (1·Cl–), and (1·2Cl–) adducts. In the chloride adducts, the highest occupied molecular orbital (HOMO) can be described as an antibonding combination of the HOMO of1with the 3p atomic orbitals (AOs) of the chloride ions, whereas the lowest occupied molecular orbital (LUMO) resembles that of the parent1. The charge transfer onto the heterocycle in the adducts increases in the order1·2Py, (1·2Cl–), and (1·Cl–). QTAIM analyses of the adducts in the gas phase reveal closed‐shell interactions, whereas NBO analyses indicate negative hyperconjugation as the main formation pathway in these complexes. This description agrees with the Alcock model suggested for secondary bonding interactions between atoms of heavy p‐block elements and atoms with lone pairs.
Straightforward Synthesis of Aromatic Imines from Alcohols and Amines or Nitroarenes Using an Impregnated Copper Catalyst
Authors: Pérez Juana M. , Cano Rafael , Yus Miguel , Ramón Diego J. 
Published: July 2012

AbstractThe impregnated copper on magnetite catalyst is a versatile system for the synthesis of imines starting from alcohols and amines. This catalyst does not require any type of expensive and difficult to handle organic ligand or typical transition metals, and provides excellent yields achievable under mild reaction conditions. Moreover, the catalyst is very easy to remove from the reaction medium by simply using a magnet. The one‐pot process of dehydrogenation of alcohols in the presence of aniline followed by aqueous hydrolysis gave pure alcohols in excellent yields. In addition to amines, nitroarenes could be used as the nitrogen‐containing reagent. In the case of primary amines the expected imines were successfully prepared under similar reaction conditions.
Aziridines in Formal [3+2] Cycloadditions: Synthesis of Five‐Membered Heterocycles
Authors: Cardoso Ana L. , Pinho e Melo Teresa M. V. D. 
Published: July 2012

AbstractChemistry based on ring opening of aziridines has been widely studied in organic synthesis. However, it has mainly been centered on ring opening by nucleophiles and on cycloaddition of azomethine ylides generated by carbon–carbon bond cleavage. In recent years, significant effort has been dedicated to study of the participation of aziridines in formal [3+2] cycloadditions, which provide routes for the construction of a wide variety of functionalized five‐membered heterocycles. Here we review the most relevant aspects of the reactivities and selectivities of aziridines as masked zwitterionic 1,3‐dipoles generated through C–N bond cleavage.
Single‐Step Radiosynthesis of “18F‐Labeled Click Synthons” from Azide‐Functionalized Diaryliodonium Salts
Authors: Chun Joong‐Hyun , Pike Victor W. 
Published: July 2012

AbstractPositron emission tomography (PET) is an increasingly important biomedical imaging technique that relies on the development of radiotracers labeled with positron emitters to achieve biochemical specificity. Fluorine‐18 (t1/2 = 109.7 min) is an attractive positron‐emitting radiolabel for organic radiotracers, primarily because of its longer half‐life and greater availability relative to those of the main alternative, carbon‐11 (t1/2 = 20.4 min). Rapid, simple methods are sought for labeling prospective PET radiotracers with fluorine‐18 from cyclotron‐produced aqueous [18F]fluoride ion, which must often be converted first into a suitably reactive labeling synthon for use in a subsequent labeling reaction. The use of 18F‐labeled synthons in “click chemistry” is attracting increasing attention for labeling PET radiotracers. Herein we describe rapid, single‐step radiosynthesis of azido‐ or azidomethyl‐bearing [18F]fluoroarenes from the reactions of diaryliodonium salts with no‐carrier‐added [18F]fluoride ion within a microfluidic apparatus to provide previously poorly accessible 18F‐labeled click synthons in radiochemical yields of 15 % for 4‐[18F]fluorophenyl azide and about 40 % for each of the [18F](azidomethyl)fluorobenzenes. The radiosynthesis of the latter synthons was possible under “wet conditions”, so obviating the need to dry the cyclotron‐produced [18F]fluoride ion and greatly enhancing the practicality of the method.
Krueppel‐like factor 15 regulates Wnt/β‐catenin transcription and controls cardiac progenitor cell fate in the postnatal heart
Authors: Noack Claudia , Zafiriou Maria‐Patapia , Schaeffer Hans‐Joerg , Renger Anke , Pavlova Elena , Dietz Rainer , Zimmermann Wolfram H. , Bergmann Martin W. , Zelarayán Laura C. 
Published: July 2012

AbstractWnt/β‐catenin signalling controls adult heart remodelling in part via regulation of cardiac progenitor cell (CPC) differentiation. An enhanced understanding of mechanisms controlling CPC biology might facilitate the development of new therapeutic strategies in heart failure. We identified and characterized a novel cardiac interaction between Krueppel‐like factor 15 and components of the Wnt/β‐catenin pathway leading to inhibition of transcription. In vitro mutation, reporter assays and co‐localization analyses revealed that KLF15 requires both the C‐terminus, necessary for nuclear localization, and a minimal N‐terminal regulatory region to inhibit transcription. In line with this, functional Klf15 knock‐out mice exhibited cardiac β‐catenin transcriptional activation along with functional cardiac deterioration in normal homeostasis and upon hypertrophy. We further provide in vivo and in vitro evidences for preferential endothelial lineage differentiation of CPCs upon KLF15 deletion. Via inhibition of β‐catenin transcription, KLF15 controls CPC homeostasis in the adult heart similar to embryonic cardiogenesis. This knowledge may provide a tool for reactivation of this apparently dormant CPC population in the adult heart and thus be an attractive approach to enhance endogenous cardiac repair.
Seismic risk prioritization of residential buildings in Istanbul
Authors: Yakut Ahmet , Sucuoğlu Halûk , Akkar Sinan 
Published: July 2012

SUMMARYA large scale seismic risk prioritization study was conducted for medium‐rise, gravity‐designed reinforced concrete residential buildings in Istanbul. The implemented procedure was based on evaluating selected building parameters that could be easily observed or measured during a systematic sidewalk survey. The survey was actually conducted on approximately 100,000 buildings in the six subprovinces of Istanbul over the period 2004–2009 by a large team of trained surveyors. The collected data were processed to calculate a safety score for each building, which is in turn used for ranking the surveyed buildings with respect to their expected seismic performance under the calculated ground motion intensities produced for a scenario earthquake of M7.5 along the Marmara Sea Fault. The basic objective of this laborious study was to identify the buildings that would be likely to sustain severe damage or suffer collapse during the expected Istanbul earthquake. Accordingly, a rational risk reduction planning can be conducted for minimizing the life and property losses. This paper presents the methodology, results of field surveys and risks evaluated in 100,000 buildings. As a result, 52,000 buildings have been classified as ‘high risk’, that is, expected to sustain severe damage or collapse during the scenario event. Copyright © 2012 John Wiley & Sons, Ltd.
Expected earthquake damage and repair costs in reinforced concrete frame buildings
Authors: Ramirez C. M. , Liel A. B. , Mitrani‐Reiser J. , Haselton C. B. , Spear A. D. , Steiner J. , Deierlein G. G. , Miranda E. 
Published: July 2012

SUMMARYThis study examines the expected cost of repairing earthquake damage in a set of 30 archetype reinforced concrete moment frame buildings. Varying in height from 1 to 20 stories, these archetype buildings are representative of office buildings with special RC moment frames, designed according to modern seismic codes. Economic losses associated with repair are computed using a performance‐based earthquake engineering framework, which integrates the site‐specific seismic hazard, structural response, damage to building components and contents, and the resulting repair costs. Results are presented in terms of expected losses under the design basis earthquake, expected annual losses, and present value of life cycle losses. Expected annual economic losses for the set of RC frame buildings are approximately 1.0% of building replacement cost for the high seismic California site considered. Repair costs are shown to vary significantly depending on building height and other architectural and structural design parameters. These metrics provide important information about the level of economic losses expected in code‐conforming structures and the effect of design decisions on the earthquake losses. Copyright © 2012 John Wiley & Sons, Ltd.