bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tin Oxide Nanoparticles and SnO2/SiO2 Hybrid Materials by Twin Polymerization Using Tin(IV) Alkoxides
Authors: Leonhardt Christian , Brumm Susann , Seifert Andreas , Cox Gerhard , Lange Arno , Rüffer Tobias , Schaarschmidt Dieter , Lang Heinrich , Jöhrmann Nathanael , Hietschold Michael , Simon Frank , Mehring Michael 
Published: October 2013

AbstractTwin polymerization was used to prepare composite materials composed of SnO2 nanoparticles entrapped in a polymer matrix. Novel, well‐defined tin‐containing molecular precursors, so‐called twin monomers, were synthesized by transesterification starting from Sn(OR)4 (R=tBu, tAm) to give Sn(OCH2C4H3O)4 (1), [Sn(OCH2C4H3S)4⋅HOCH2C4H3S]2 (2), [Sn(OCH2‐2‐OCH3C6H4)4⋅HOCH2‐2‐OCH3C6H4]2 (3), [Sn(OCH2‐2,4‐(OCH3)2C6H3)4⋅HOCH2‐2,4‐(OCH3)2C6H3]2 (4), 2,2′‐spirobi[4H‐1,3,2‐benzodioxastannine] (5), 2,2′‐spirobi[6‐methylbenzo(4H‐1,3,2)‐dioxastannine] (6), and 2,2′‐spirobi[6‐methoxybenzo(4H‐1,3,2)dioxastannine] (7). 13C and 119Sn NMR spectroscopy in the solid state and in solution as well as IR spectroscopy and elemental analysis were used to characterize the tin alkoxides. The molecular structures of compounds 2 and 3 were determined by single‐crystal X‐ray diffraction analysis. The moisture sensitivity of the tin(IV) alkoxides was demonstrated by the formation of the tin oxocluster [Sn3(μ3‐O)(μ2‐OH)(μ2‐OCH2C4H3S)3(OCH2C4H3S)6(HOCH2C4H3S)]2 (2 a), a hydrolysis product of compound 2. Polymerization reactions in the melt (for 1 and 5) and in solution (for 2–4) resulted in cross‐linked nanocomposites of the type polymer/SnO2. Subsequent oxidation of the composites gave SnO2 with BET surface areas up to 178 m2 g−1. Simultaneous twin polymerization of compounds 5–7 with the silicon derivative 2,2′‐spirobi[4H‐1,3,2‐benzodioxasiline] resulted in the formation of polymer/SnO2/SiO2 hybrid materials. Oxidation gave porous materials with SnO2 nanoparticles embedded in a silica network with BET surface areas up to 378 m2 g−1. The silica acts as a crystal growth inhibitor, which prevents sintering of the SnO2 nanoparticles 20–32 nm in size.
Shape‐Controlled Ceria‐based Nanostructures for Catalysis Applications
Authors: Qiao Zhen‐An , Wu Zili , Dai Sheng 
Published: October 2013

AbstractAmong oxide catalysts, ceria is a technologically important material because of its wide applications as a promoter in three‐way catalysts for the elimination of toxic exhaust gases, low‐temperature water–gas‐shift reaction, oxygen sensors, oxygen permeation membrane systems, and fuel cells. The catalytic activities of cerium oxide are highly dependent on interfacial structures and nanocrystal morphologies. This Minireview highlights the recent progress in the research of ceria nanoshapes as both catalysts and catalyst supports, including the synthesis, structure characterization, catalytic properties, surface chemistry, as well as reaction mechanisms. Insights from in situ spectroscopy study and theoretical modeling of nanostructured ceria‐based materials have shed light on the origin of the ceria shape effect. It is suggested that the surface structure of ceria controls the catalytic activity and selectivity through structure‐dependent surface‐site geometry, surface vacancy formation energy, defect sites, and coordinatively unsaturated sites on ceria. The morphology‐dependent catalysis in ceria has offered a new strategy to finely tune the catalytic activity and selectivity through shape control without altering the catalyst composition. A brief summary and an outlook on this research field will be presented at the end.
The Effect of Lattice Strain on the Catalytic Properties of Pd Nanocrystals
Authors: Kuo Chun‐Hong , Lamontagne Leo K. , Brodsky Casey N. , Chou Lien‐Yang , Zhuang Jia , Sneed Brian T. , Sheehan Margaret K. , Tsung Chia‐Kuang 
Published: October 2013

AbstractThe effect of lattice strain on the catalytic properties of Pd nanoparticles is systematically studied. Synthetic strategies for the preparation of a series of shape‐controlled Pd nanocrystals with lattice strain generated from different sources has been developed. All of these nanocrystals were created with the same capping agent under similar reaction conditions. First, a series of Pd nanoparticles was synthesized that were enclosed in {111} surfaces: Single‐crystalline Pd octahedra, single‐crystalline AuPd core–shell octahedra, and twinned Pd icosahedra. Next, various {100}‐terminated particles were synthesized: Single‐crystalline Pd cubes and single‐crystalline AuPd core–shell cubes. Different extents of lattice strain were evident by comparing the X‐ray diffraction patterns of these particles. During electrocatalysis, decreased potentials for CO stripping and increased current densities for formic‐acid oxidation were observed for the strained nanoparticles. In the gas‐phase hydrogenation of ethylene, the activities of the strained nanoparticles were lower than those of the single‐crystalline Pd nanoparticles, perhaps owing to a larger amount of cetyl trimethylammonium bromide on the surface.
Exposed Surfaces on Shape‐Controlled Ceria Nanoparticles Revealed through AC‐TEM and Water–Gas Shift Reactivity
Authors: Agarwal Shilpa , Lefferts Leon , Mojet Barbara L. , Ligthart D. A. J. Michel , Hensen Emiel J. M. , Mitchell David R. G. , Erasmus Willem J. , Anderson Bruce G. , Olivier Ezra J. , Neethling Johannes H. , Datye Abhaya K. 
Published: October 2013

AbstractAberration‐corrected transmission electron microscopy and high‐angle annular dark field imaging was used to investigate the surface structures and internal defects of CeO2 nanoparticles (octahedra, rods, and cubes). Further, their catalytic reactivity in the water–gas shift (WGS) reaction and the exposed surface sites by using FTIR spectroscopy were tested. Rods and octahedra expose stable (111) surfaces whereas cubes have primarily (100) facets. Rods also had internal voids and surface steps. The exposed planes are consistent with observed reactivity patterns, and the normalized WGS reactivity of octahedra and rods were similar, but the cubes were more reactive. In situ FTIR spectroscopy showed that rods and octahedra exhibit similar spectra for OH groups and that carbonates and formates formed upon exposure to CO whereas for cubes clear differences were observed. These results provide definitive information on the nature of the exposed surfaces in these CeO2 nanostructures and their influence on the WGS reactivity.
Improvement of robust smart‐card‐based password authentication scheme
Authors: Jiang Qi , Ma Jianfeng , Li Guangsong , Li Xinghua 
Published: October 2013

SUMMARYSmart‐card‐based password authentication scheme is one of the commonly used mechanisms to prevent unauthorized service and resource access and to remove the potential security threats over the insecure networks and has been investigated extensively in the last decade. Recently, Chen et al. proposed a smart‐card‐based password authentication scheme and claimed that the scheme can withstand offline password guessing attacks even if the information stored in the smart card is extracted by the adversary. However, we observe that the scheme of Chen et al. is insecure against offline password guessing attacks in this case. To remedy this security problem, we propose an improved authentication protocol, which inherits the merits of the scheme of Chen et al. and is free from the security flaw of their scheme. Compared with the previous schemes, our improved scheme provides more security guarantees while keeping efficiency. Copyright © 2013 John Wiley & Sons, Ltd.
Are food restriction and pressure‐to‐eat parenting practices associated with adolescent disordered eating behaviors?
Authors: Loth Katie A. , MacLehose Richard F. , Fulkerson Jayne A. , Crow Scott , Neumark‐Sztainer Dianne 
Published: October 2013

ABSTRACTObjectiveTo examine associations between parental pressure‐to‐eat and food restriction and adolescent disordered eating behaviors, within a sample of parent–adolescent pairs.MethodAdolescents (N = 2,231) and their parents (N = 3,431) participated in two, coordinated, population‐based studies designed to examine factors associated with weight and weight‐related behaviors in adolescents.ResultsOverall, higher levels of pressure‐to‐eat or food restriction were significantly and positively associated with use of disordered eating behaviors among boys. For every one unit increase [Scale Range: 1 (low control) to 4 (high control)] in mothers' food restriction, boys were twice as likely to engage in extreme weight control behaviors (p ≤ .01). Examination of the association between food‐related parenting practices and disordered eating behaviors among girls revealed fewer significant associations. However, analyses revealed that for every one unit increase in mothers' food restriction, girls were 1.33 times more likely to engage in extreme weight control behaviors (p = .04).DiscussionStudy findings provide evidence of an association between controlling food‐related parenting practices and adolescent disordered eating behaviors, particularly in boys. Future longitudinal research is needed to establish directionality of observed associations. © 2013 Wiley Periodicals, Inc. (Int J Eat Disord 2014; 47:310–314)
Mitochondrial DNA inference between European populations of Tanymastix stagnalis and their glacial survival in Scandinavia
Authors: Arukwe Augustine , Langeland Arnfinn 
Published: October 2013

AbstractThe early observation from 1914 of Tanymastix stagnalis in Norway was not repeated recently, showing a rare and restricted distribution of this species. All four sampled localities were concentrated in the same area of the Trollheimen Mountains with altitudes of 900–1244 m above sea level. In March 2002, a new population of T. stagnalis was observed at about 50 km north of Madrid at an altitude of 1350 m. In general, all habitats with T. stagnalis were fishless shallow ponds and varied in size from 1 to about 300 m2. Natural variability of the global temperature is well accepted, but recent climate models have predicted increases in global average temperature. Based on the new biogeographical distribution, diurnal temperature variations, and biological evidence (inference with the analysis of mitochondria DNA), the immigration history of T. stagnalis was considered on the basis of two opposing immigration theories and in relation to the implications of global climate change. Two immigration theories, namely – the Tabula rasa and Nunatak, have prevailed in explaining the present distribution of plants and animals in Scandinavia. It was concluded that the rare occurrence of T. stagnalis in Norway fits into the Nunatak theory and that the species probably survived, at least, the last glaciation on Nunataks or coast refuges located in central northwestern Norway at Møre mountain and coast areas.
Possible combined effects of climate change, deforestation, and harvesting on the epiphyte Catopsis compacta: a multidisciplinary approach
Authors: del Castillo Rafael F. , Trujillo‐Argueta Sonia , Rivera‐García Raul , Gómez‐Ocampo Zaneli , Mondragón‐Chaparro Demetria 
Published: October 2013

AbstractClimate change, habitat loss, and harvesting are potential drivers of species extinction. These factors are unlikely to act on isolation, but their combined effects are poorly understood. We explored these effects in Catopsis compacta, an epiphytic bromeliad commercially harvested in Oaxaca, Mexico. We analyzed local climate change projections, the dynamics of the vegetation patches, the distribution of Catopsis in the patches, together with population genetics and demographic information. A drying and warming climate trend projected by most climate change models may contribute to explain the poor forest regeneration. Catopsis shows a positive mean stochastic population growth. A PVA reveals that quasi‐extinction probabilities are not significantly affected by the current levels of harvesting or by a high drop in the frequency of wet years (2%) but increase sharply when harvesting intensity duplicates. Genetic analyses show a high population genetic diversity, and no evidences of population subdivision or a past bottleneck. Colonization mostly takes place on hosts at the edges of the fragments. Over the last 27 years, the vegetation cover has being lost at a 0.028 years−1 rate, but fragment perimeter has increased 0.076 years−1. The increases in fragment perimeter and vegetation openness, likely caused by climate change and logging, appear to increase the habitat of Catopsis, enhance gene flow, and maintain a growing and highly genetically diverse population, in spite of harvesting. Our study evidences conflicting requirements between the epiphytes and their hosts and antagonistic effects of climate change and fragmentation with harvesting on a species that can exploit open spaces in the forest. A full understanding of the consequences of potential threatening factors on species persistence or extinction requires the inspection of the interactions of these factors among each other and their effects on both the focus species and the species on which this species depends.
A bioturbation classification of European marine infaunal invertebrates
Authors: Queirós Ana M. , Birchenough Silvana N. R. , Bremner Julie , Godbold Jasmin A. , Parker Ruth E. , Romero‐Ramirez Alicia , Reiss Henning , Solan Martin , Somerfield Paul J. , Van Colen Carl , Van Hoey Gert , Widdicombe Stephen 
Published: October 2013

AbstractBioturbation, the biogenic modification of sediments through particle reworking and burrow ventilation, is a key mediator of many important geochemical processes in marine systems. In situ quantification of bioturbation can be achieved in a myriad of ways, requiring expert knowledge, technology, and resources not always available, and not feasible in some settings. Where dedicated research programmes do not exist, a practical alternative is the adoption of a trait‐based approach to estimate community bioturbation potential (BPc). This index can be calculated from inventories of species, abundance and biomass data (routinely available for many systems), and a functional classification of organism traits associated with sediment mixing (less available). Presently, however, there is no agreed standard categorization for the reworking mode and mobility of benthic species. Based on information from the literature and expert opinion, we provide a functional classification for 1033 benthic invertebrate species from the northwest European continental shelf, as a tool to enable the standardized calculation of BPc in the region. Future uses of this classification table will increase the comparability and utility of large‐scale assessments of ecosystem processes and functioning influenced by bioturbation (e.g., to support legislation). The key strengths, assumptions, and limitations of BPc as a metric are critically reviewed, offering guidelines for its calculation and application.
Adaptive divergence along environmental gradients in a climate‐change‐sensitive mammal
Authors: Henry P. , Russello M. A. 
Published: October 2013

AbstractIn the face of predicted climate change, a broader understanding of biotic responses to varying environments has become increasingly important within the context of biodiversity conservation. Local adaptation is one potential option, yet remarkably few studies have harnessed genomic tools to evaluate the efficacy of this response within natural populations. Here, we show evidence of selection driving divergence of a climate‐change‐sensitive mammal, the American pika (Ochotona princeps), distributed along elevation gradients at its northern range margin in the Coast Mountains of British Columbia (BC), Canada. We employed amplified‐fragment‐length‐polymorphism‐based genomic scans to conduct genomewide searches for candidate loci among populations inhabiting varying environments from sea level to 1500 m. Using several independent approaches to outlier locus detection, we identified 68 candidate loci putatively under selection (out of a total 1509 screened), 15 of which displayed significant associations with environmental variables including annual precipitation and maximum summer temperature. These candidate loci may represent important targets for predicting pika responses to climate change and informing novel approaches to wildlife conservation in a changing world.
Application of Pulse Radiolysis to Mechanistic Investigations of Water Oxidation Catalysis
Authors: Polyansky Dmitry E. , Hurst James K. , Lymar Sergei V. 
Published: October 2013

AbstractRadiolysis is a powerful technique capable of generating both inorganic and organic strong one‐electron oxidants over a wide range of aqueous medium conditions. Accordingly, current pulse radiolysis methods are quite advanced and have been productively used to study dynamics of many types of redox reactions for several decades. Nonetheless, despite its apparent usefulness for gaining mechanistic insights into water oxidation catalysis through probing normally inaccessible oxidation states of the catalysts, pulse radiolysis has only infrequently been applied to this purpose. In this paper, we identify those oxidizing radicals deemed most suited to these types of studies and describe methods for their radiolytic generation, review the scant literature on pulse radiolysis studies of both heterogeneous and homogeneous water oxidation catalysts, and discuss results of our own investigations of two dimeric and one monomeric ruthenium‐based catalysts, each of which appears to oxidize water by a distinct pathway. The optical spectra and redox dynamics of transient species determined have in each case provided information central to evaluating proposed catalytic mechanisms. Moreover, quantitative “over‐oxidation” by generating a stoichiometric excess amount of radicals has permitted investigation of an intermediate formed from a highly reactive precursor, demonstrating the unique capability of the pulse radiolysis method. As illustrated by these examples, this technique is broadly applicable to investigations of catalyzed water oxidation, which has the potential to become a method of choice for detecting and characterizing reaction transients.
Donor Behaviour of Anionic and Asymmetric Phosphanido Derivatives of Platinum and Palladium
Authors: Arias Andersson , Forniés Juan , Fortuño Consuelo , Martín Antonio , Mastrorilli Piero , Gallo Vito , Latronico Mario , Todisco Stefano 
Published: October 2013

AbstractThe reactions of [Ag(OClO3)(PPh3)] with [NBu4][(C6F5)2Pt(μ‐PPh2)2M(hq)], [NBu4][(C6F5)2Pt(μ‐PPh2)2M(bq)], [NBu4][(C6F5)2Pt(μ‐PPh2)2M(pic)] and [NBu4][(C6F5)2Pt(μ‐PPh2)2Pt(C6F5)(tht)] (M = Pt, Pd; hq = 8‐hydroxyquinolinate, bq = benzoquinolinate, pic = picolinate, tht = tetrahydrothiophene) afford the corresponding neutral adducts [(C6F5)2Pt(μ‐PPh2)2(μ‐AgPPh3)M(bq)] (M = Pt, 1; Pd, 2), [(C6F5)2Pt(μ‐PPh2)2(μ‐AgPPh3)M(hq)] (M = Pt, 3; Pd, 4) [(C6F5)2Pt(μ‐PPh2)2(μ‐AgPPh3)Pt(C6F5)(tht)] (5) and [(C6F5)2Pt(μ‐PPh2)2M(pic‐AgPPh3)] (M = Pt, 6; Pd, 7) as yellow solids. The XRD structures of 1–5, in which a [AgPPh3]+ moiety bridges the metal centres, were confirmed in solution at low temperature. At room temperature, a dynamic process for the [AgPPh3]+ moiety, which passes from the top to the bottom part of the molecules 1–5, was ascertained. For 6 and 7, the XRD analyses revealed structures in which the [AgPPh3]+ moiety is linked to the picolinate oxygen atom bonded to the M centre; however, although such a structure was confirmed in solution for the Pt–Pd species 7, the stable form of the Pt–Pt species 6 in solution is that with the [AgPPh3]+ moiety bridging the metal centres.
Synthesis, Structure, and Magnetic Study of Two Tridecanuclear Planar Cobalt Clusters with Unique Core Geometries
Authors: Peng Yan , Tian Chong‐Bin , Lan Yan‐Hua , Magnani Nicola , Li Qi‐Peng , Zhang Hua‐Bin , Powell Annie K. , Du Shao‐Wu 
Published: October 2013

AbstractThe reaction of Co(NO3)2·6H2O with N,N‐diethanolamine (H2L1) in the presence of sodium acetate, using triethylamine as a base, leads to a tridecanuclear mixed‐valent cobalt cluster [CoII9CoIII4(OH)6(H2O)2(L1)8(OAc)4](NO3)4·24H2O (1). Similar reaction with a newly designed hydroxy‐ and nitrogen‐rich chelating ligand 2‐[bis(pyridin‐2‐ylmethyl)amino]‐2‐(hydroxymethyl)propane‐1,3‐diol (H2L2) gives a mixed‐valent Co13 cluster [CoII7CoIII6(OH)12(L2)6](NO3)8·10H2O (2). The cobalt ions in both 1 and 2 are nearly coplanar, forming a novel shieldlike configuration for 1 and a unique hexagram structure for 2, both of which have not been observed for the polynuclear cobalt clusters. The magnetic susceptibility investigation showed that complexes 1 and 2 exhibited ferromagnetic coupling between CoII ions. Further magnetic studies revealed a slight frequency dependence of 2, which suggests that 2 might be a single‐molecule magnet.
Direct Synthesis of Ag Nanoparticles Incorporated on a Mesoporous Hybrid Material as a Sensitive Sensor for the Simultaneous Determination of Dihydroxybenzenes Isomers
Authors: Canevari Thiago C. , Raymundo‐Pereira Paulo A. , Landers Richard , Machado Sérgio A. S. 
Published: October 2013

AbstractThis paper describes the synthesis, characterization, and applications of a mesoporous silica/ multiwalled carbon nanotube (SiO2/MWCNT) hybrid material, which was obtained by a sol–gel process and decorated with silver nanoparticles (AgNPs) ranging in size from 5 to 8 nm. The AgNPs were prepared directly on the surface of the SiO2/MWCNTs material by using N,N‐dimethylformamide (DMF) as the reducing agent, and the resulting material was designated Ag/SiO2/MWCNT. The Ag/SiO2/MWCNT material was characterized by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), high‐resolution transmission electron microscopy (HR‐TEM), and X‐ray photoelectron spectroscopy (XPS). A glassy carbon electrode, modified with the Ag/SiO2/MWCNT material, was used in the development of a sensitive electrochemical sensor for the determination of hydroquinone and catechol in the presence of resorcinol by squarewave voltammetry. Well‐defined and separate oxidation peaks were observed in phosphate buffer solution (PBS) at pH 7. The Ag/SiO2/MWCNT‐modified electrode exhibited high sensitivity for the simultaneous determination of hydroquinone and catechol in the presence of resorcinol, and the limits of detection for hydroquinone and catechol are 0.0117 and 0.0121 μM, respectively. No significant interference was seen for 2,6‐dichloroindophenol, phenol, 4‐nitrophenol, and nitrite ions in the detection of dihydroxybenzenes. Our study demonstrates that the resultant Ag/SiO2/MWCNT‐modified electrode can be used for hydroquinone and catechol detection in the presence of resorcinol and other potentially interfering materials in river water samples.
NaRb7(Si4–xGex)2 – Soluble Zintl Phases Containing Heteroatomic Tetrahedral ­[Si4–xGex]4– Clusters
Authors: Waibel Markus , Pecher Oliver , Mausolf Bernhard , Haarmann Frank , Fässler Thomas F. 
Published: October 2013

AbstractThe quaternary phases NaRb7(Si4–xGex)2 (x = 1–3) crystallize with an NaRb7Ge8‐type structure and contain tetrahedral four‐atom clusters that consist of Si and Ge atoms. The quaternary phases possess larger cell volumes with increasing Ge amount. The formation of heteroatomic [Si4–xGex]4– clusters is indicated by chemically different Si environments, which were analyzed by means of solid‐state 29Si MAS (magic‐angle spinning) NMR spectroscopy of a 29Si‐enriched NaRb7(Si4–xGex)2 sample with x = 0.5 as well as quantum chemical calculations of the NMR coupling parameters. NaRb7(Si4–xGex)2 represents another rare example of a phase with exclusively tetrahedral clusters that readily dissolves in liquid ammonia. The nature of the heteroatomic clusters was further investigated by dissolution of NaRb7(Si4–xGex)2 with x = 2 in liquid ammonia. In the presence of MesCu (Mes = mesityl) and 18‐crown‐6 as a sequestering agent, crystals with the composition [Rb(18‐crown‐6)]2Rb2[(MesCu)2(Si4–xGex)](NH3)11 were isolated with x = 2.2(1). [(MesCu)2(Si4–xGex)]4– represents another isomer of a MesCu‐stabilized tetrahedral anion and supports the observation that Zintl phases, which contain solely tetrahedranide subunits, represent a new class of soluble Zintl phases.