bluuebunny/crossref_metadata_2025_split huggingface dataset:
Macromolecule‐to‐Amphiphile Conversion Process of a Polyoxometalate–Polymer Hybrid and Assembled Hybrid Vesicles
Authors: Xiao Yu , Han Yao‐Kun , Xia Nan , Hu Min‐Biao , Zheng Ping , Wang Wei 
Published: July 2012

AbstractWe report our findings on the macromolecule‐to‐amphiphile conversion process of a polyoxometalate–polymer hybrid and the assembled hybrid vesicles formed by aggregation of the hybrid amphiphile. The polyoxometalate–polymer hybrid is composed of a polyoxometalate (POM) cluster, which is covered by five tetrabutylammonium (Bu4N+) countercations, and a polystyrene (PS) chain. Through a cation‐exchange process the Bu4N+ countercations can be replaced by protons to form a hybrid amphiphile composed of a hydrophilic, protonated POM cluster and a hydrophobic PS chain. By implementing a directed one‐dimensional diffusion and analyzing the diffusion data, we confirmed that the diffusion of solvated protons rather than macromolecules or aggregates is the key factor controlling the conversion process. Once the giant hybrid amphiphiles were formed, they immediately assembled into kinetically favored vesicular aggregates. During subsequent annealing these vesicular aggregates were transformed into thermodynamically stable vesicular aggregates with a perfect vesicle structure. The success in the preparation of the POM‐containing hybrid vesicles provides us with an opportunity of preparing POM‐functionalized vesicles.
Bluish‐Green BMes2‐Functionalized PtII Complexes for High Efficiency PhOLEDs: Impact of the BMes2 Location on Emission Color
Authors: Rao Ying‐Li , Schoenmakers Dylan , Chang Yi‐Lu , Lu Jia‐Sheng , Lu Zheng‐Hong , Kang Youngjin , Wang Suning 
Published: July 2012

AbstractNew phosphorescent PtII compounds based on dimesitylboron (BMes2)‐functionalized 2‐phenylpyridyl (ppy) N,C‐chelate ligands and an acetylacetonato ancillary ligand have been achieved. We have found that BMes2 substitution at the 4′‐position of the phenyl ring can blue‐shift the phosphorescent emission energy of the PtII compound by approximately 50 nm, compared to the 5′‐BMes2 substituted analogue, without substantial loss of luminescent quantum efficiencies. The emission color of the 4′‐BMes2 substituted PtII compound, Pt(Bppy)(acac) (1) can be further tuned by the introduction of a substituent group at the 3′‐position of the phenyl ring. A methyl substituent red‐shifts the emission energy of 1 by approximately 10 nm whereas a fluoro substituent blue‐shifts the emission energy by about 6 nm. Using this strategy, three bright blue‐green phosphorescent PtII compounds 1, 2 and 3 with emission energy at 481, 492, and 475 nm and ΦPL=0.43, 0.26 and 0.25, respectively, have been achieved. In addition, we have examined the impact of BMes2 substitution on 3,5‐dipyridylbenzene (dpb) N,C,N‐chelate PtII compounds by synthesizing compound 4, Pt(Bdpb)Cl, which has a BMes2 group at the 4′‐position of the benzene ring. Compound 4 has a phosphorescent emission band at 485 nm and ΦPL=0.70. Highly efficient blue‐green electroluminescent (EL) devices with a double‐layer structure and compounds 1, 3 or 4 as the phosphorescent dopant have been fabricated. At 100 cd m−2 luminance, EL devices based on 1, 3 and 4 with an external quantum efficiency of 4.7, 6.5 and 13.4 %, respectively, have been achieved.
Fluorinated Organocatalysts for the Enantioselective Epoxidation of Enals: Molecular Preorganisation by the Fluorine‐Iminium Ion Gauche Effect
Authors: Tanzer Eva‐Maria , Zimmer Lucie E. , Schweizer W. Bernd , Gilmour Ryan 
Published: July 2012

AbstractThe fluorine‐iminium ion gauche effect is triggered upon union of a secondary β‐fluoroamine and an α,β‐unsaturated aldehyde, providing a useful strategy for controlling the molecular topology of intermediates that are central to organocatalytic processes. The β‐fluoroamine (S)‐2‐(fluorodiphenylmethyl)pyrrolidine (1) is an effective catalyst for the enantioselective epoxidation of α,β‐unsaturated aldehydes. A process of structural editing has revealed that the efficiency of this catalyst is due to the (fluorodiphenyl)methyl group when it is embedded in a β‐fluoroiminium motif. Epoxidations of challenging cyclic α,β‐disubstituted, β,β‐disubstituted and α,β,β‐trisubstituted enals catalysed by 1 proceed with excellent levels of enantiocontrol (up to 98 % ee).
Facile Synthesis of Fluorine‐Substituted Benzothiadiazole‐Based Organic Semiconductors and Their Use in Solution‐Processed Small‐Molecule Organic Solar Cells
Authors: Cho Nara , Song Kihyung , Lee Jae Kwan , Ko Jaejung 
Published: July 2012

AbstractA facile new protocol for the synthesis of iodinated derivatives of fluorinated benzothiadiazoles is demonstrated for the production of p‐type semiconducting materials. The newly synthesized small‐molecule compounds bis[TPA‐diTh]‐MonoF‐BT and bis[TPA‐diTh]‐DiF‐BT exhibited a power conversion efficiency of 2.95 % and a high open‐circuit voltage of 0.85 V in solution‐processed small‐molecule organic solar cells.
Facile Metalation of Silicon and Germanium Analogues of Thiocarboxylic Acids with a Manganese(II) Hydride Precursor
Authors: Yao Shenglai , Xiong Yun , Driess Matthias 
Published: July 2012

AbstractSynthesis and characterization of the first manganese(II)‐containing heavier thiocarboxylate analogues, [LDipSi(S)OMnLDep] (4; LDip=CH[C(Me)N(2,6‐iPr2C6H3)]2, LDep=CH[C(Me)N(2,6‐Et2C6H3)]2) and [LDipGe(S)OMnLDep] (5) are described. They are accessible through reaction of the silicon and germanium analogues of the respective thiocarboxylic acids [LDipE(S)OH] (E=Si, Ge) with the β‐diketiminato (nacnac) manganese(II) hydride precursor [(LDepMn)2(μ‐H)2] (3) in high yield. The first Mn nacnac hydride 3 has been prepared by the reaction of manganese bromide [(LDepMn)2(μ‐Br)2] (2) with KBEt3H. Compounds 4 and 5 represent the first transition‐metal heavier thiocarboxylates with the SiS and GeS functionalities. All new compounds are paramagnetic and were characterized by elemental analysis, IR spectroscopy, MS (EI), and single‐crystal X‐ray diffraction analyses. Due to the N→E (E=Si, Ge) and E=S→Mn donor–acceptor interaction as well as the carboxylate‐like π‐electron delocalization within the E(S)O moieties, the ES double bonds in these compounds are resonance stabilized.
Bulge‐like Asymmetric Heterodye Clustering in DNA Duplex Results in Efficient Quenching of Background Emission Based on the Maximized Excitonic Interaction
Authors: Fujii Taiga , Hara Yuichi , Osawa Takuya , Kashida Hiromu , Liang Xingguo , Yoshida Yasuko , Asanuma Hiroyuki 
Published: July 2012

AbstractAsymmetric dye clusters with a single fluorophore (Cy3) and multiple quenchers (4′‐methylthioazobenzene‐4‐carboxylate, methyl red, and 4′‐dimethylamino‐2‐nitroazobenzene‐4‐carboxylate) were prepared. The dye and one‐to‐five quenchers were tethered through D‐threoninol to opposite strands of a DNA duplex. NMR analysis revealed that the clusters with a single fluorophore and two quenchers formed a sandwich‐like structure (antiparallel H‐aggregates). The melting temperatures of all the heteroclusters were almost the same, although structural distortion should become larger, as the number of quenchers increased. An asymmetric heterocluster of a single fluorophore and two quenchers showed larger excitonic interaction (i.e., hypochromicity of Cy3), than did a single Cy3 and a single quencher. Due to the larger exciton coupling between the dyes, the 1:2 heterocluster suppressed the background emission more efficiently than the 1:1 cluster. However, more quenchers did not enhance quenching efficiency due to the saturation of exciton coupling with two quenchers. Finally, this asymmetric 1:2 heterocluster was introduced into the stem region of a molecular beacon (MB; also known as an in‐stem MB) targeting the fusion site in the L6 BCR‐ABL fusion gene. With this MB design, the signal/background ratio was as high as 68 due to efficient suppression of background emission resulting from the maximized excitonic interaction.
Filter design for phased‐array mr image reconstruction using super algorithm
Authors: Giovannetti Giulio , Martini Nicola , Di Lascio Nicole , Vanello Nicola , Positano Vincenzo , Hartwig Valentina , De Marchi Daniele , Lombardi Massimo , Landini Luigi , Santarelli Maria Filomena 
Published: July 2012

AbstractReceiver coils in magnetic resonance (MR) systems are used to acquire the signals emitted by the nuclei. Surface coils provide a high signal‐to‐noise ratio due to their small sensitive region but the usable field of view is also limited to the size of the sensitive region. The use of array coils permits to increase the sensitive region. The outputs from the receiver channels are combined to construct a single composite image from the data of many coils. The image reconstruction is usually performed by using root sum‐of‐squares (RSS) method, which combines data without the knowledge of the coils sensitivity but it is known to introduce bias in low‐signal regions. SUPER reconstruction permits to yield a composite image with higher contrast between high‐ and low‐signal regions than RSS algorithm, by preliminary estimating coil sensitivities using low‐pass filtering of original images. The purpose of this work is to introduce a theory for obtaining estimated coil sensitivity maps from the individual coil images and successively combining data from array elements using SUPER algorithm. Performance evaluation and comparison with RSS reconstruction were carried out with MR acquisitions performed using a 32‐elements cardiac phased‐array coil in a 3 T scanner. © 2012 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 41B: 85–93, 2012
A 28‐channel coil array for improved imaging of the optic nerve
Authors: Merrill Robb P. , Hadley J. Rock , Minalga Emilee , Kholmovski Eugene G. , Vijayakumar Sathya , Kim Seong‐Eun , Quigley Edward P. , Parker Dennis L. , Rose John W. 
Published: July 2012

AbstractThis work describes the design and construction of a radio‐frequency (RF) coil optimized for imaging the optic nerve on a Siemens 3T TIM Trio MRI scanner. The specific goals were to optimize signal sensitivity from the orbit to the optic chiasm and improve SNR over previous designs. The optic nerve (ON) coil was constructed using two fiberglass formers that fit together in a clamshell arrangement to maintain a high filling factor for any head size. This design maintains close coil‐to‐sample coupling near the eyes and around the entire head to eliminate the air void regions that occur between coil and sample when heads are imaged in one‐piece rigid head coils. The anterior mask former holds 26 overlapping coil elements in a soccer ball layout. The posterior former supports the neck and head and houses two additional overlapped coil elements, totaling to 28 elements. Signal‐to‐noise‐ratio (SNR) measurements on a custom‐made homogeneous head phantom using the optic nerve coil showed a 310% increase in SNR near the orbits and 60% increase at the optic chiasm compared to the 12‐channel Siemens head coil. Inverse g‐factor maps show that the ON coil performs well for parallel imaging over the region of the optic nerve, providing a possible reduction of eyeball motion artifacts. Images from volunteer studies demonstrate that high‐resolution imaging of the optic nerve can be achieved using 3T MRI with advanced imaging coils, leading to improved patient care for optic neuritis patients. © 2012 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 41B: 73–84, 2012
Vocal‐motor and auditory connectivity of the midbrain periaqueductal gray in a teleost fish
Authors: Kittelberger J. Matthew , Bass Andrew H. 
Published: July 2012

AbstractThe midbrain periaqueductal gray (PAG) plays a central role in the descending control of vocalization across vertebrates. The PAG has also been implicated in auditory‐vocal integration, although its precise role in such integration remains largely unexplored. Courtship and territorial interactions in plainfin midshipman fish depend on vocal communication, and the PAG is a central component of the midshipman vocal‐motor system. We made focal neurobiotin injections into the midshipman PAG to both map its auditory‐vocal circuitry and allow evolutionary comparisons with tetrapod vertebrates. These injections revealed an extensive bidirectional pattern of connectivity between the PAG and known sites in both the descending vocal‐motor and the ascending auditory systems, including portions of the telencephalon, dorsal thalamus, hypothalamus, posterior tuberculum, midbrain, and hindbrain. Injections in the medial PAG produced dense label within hindbrain auditory nuclei, whereas those confined to the lateral PAG preferentially labeled hypothalamic and midbrain auditory areas. Thus, the teleost PAG may have functional subdivisions playing different roles in vocal‐auditory integration. Together the results confirm several pathways previously identified by injections into known auditory or vocal areas and provide strong support for the hypothesis that the teleost PAG is centrally involved in auditory‐vocal integration. J. Comp. Neurol. 521:791–812, 2013. © 2012 Wiley Periodicals, Inc.
Morphological and neurochemical comparisons between pulvinar and V1 projections to V2
Authors: Marion Roan , Li Keji , Purushothaman Gopathy , Jiang Yaoguang , Casagrande Vivien A. 
Published: July 2012

AbstractThe flow of visual information is clear at the earliest stages: the retina provides the driving (main signature) activity for the lateral geniculate nucleus (LGN), which in turn drives the primary visual cortex (V1). These driving pathways can be distinguished anatomically from other modulatory pathways that innervate LGN and V1. The path of visual information after V1, however, is less clear. There are two primary feedforward projections to the secondary visual cortex (V2), one from the lateral/inferior pulvinar and the other from V1. Because both lateral/inferior pulvinar and V2 cannot be driven visually following V1 removal, either or both of these inputs to V2 could be drivers. Retinogeniculate and geniculocortical projections are privileged over modulatory projections by their layer of termination, their bouton size, and the presence of vesicular glutamate transporter 2 (Vglut2) or parvalbumin (PV). It has been suggested that such properties might also distinguish drivers from modulators in extrastriate cortex. We tested this hypothesis by comparing lateral pulvinar to V2 and V1 to V2 projections with LGN to V1 projections. We found that V1 and lateral pulvinar projections to V2 are similar in that they target the same layers and lack PV. Projections from pulvinar to V2, however, bear a greater similarity to projections from LGN to V1 because of their larger boutons (measured at the same location in V2) and positive staining for Vglut2. These data lend support to the hypothesis that the pulvinar could act as a driver for V2. J. Comp. Neurol. 521:813–832, 2013. © 2012 Wiley Periodicals, Inc.
Group Invariant Scattering
Authors: Mallat Stéphane 
Published: July 2012

AbstractThis paper constructs translation‐invariant operators on
$\font\open=msbm10 at 10pt\def\R{\hbox{\open R}}{\bf L}^2({{{\R}}}^d)$, which are Lipschitz‐continuous to the action of diffeomorphisms. A scattering propagator is a path‐ordered product of nonlinear and noncommuting operators, each of which computes the modulus of a wavelet transform. A local integration defines a windowed scattering transform, which is proved to be Lipschitz‐continuous to the action of C2 diffeomorphisms. As the window size increases, it converges to a wavelet scattering transform that is translation invariant. Scattering coefficients also provide representations of stationary processes. Expected values depend upon high‐order moments and can discriminate processes having the same power spectrum. Scattering operators are extended on L2(G), where G is a compact Lie group, and are invariant under the action of G. Combining a scattering on $\font\open=msbm10 at 10pt\def\R{\hbox{\open R}}{\bf L}^2({{{\R}}}^d)$
and on L2(SO(d)) defines a translation‐ and rotation‐invariant scattering on $\font\open=msbm10 at 10pt\def\R{\hbox{\open R}}{\bf L}^2({{{\R}}}^d)$. © 2012 Wiley Periodicals, Inc.
Space of Ricci Flows I
Authors: Chen Xiuxiong , Wang Bing 
Published: July 2012

AbstractIn this paper, we study the moduli spaces of m‐dimensional, κ‐noncollapsed Ricci flow solutions with bounded
$\int |Rm|^{{m}/{2}}$
and bounded scalar curvature. We show a weak compactness theorem for such moduli spaces and apply it to study the estimates of isoperimetric constants, the Kähler‐Ricci flows, and the moduli spaces of gradient shrinking solitons. © 2012 Wiley Periodicals, Inc.
Mass Spectrometric Monitoring of the Gas Phase during the CVD of Copper from Copper Cyclopentadienyl Triethylphosphine
Authors: Turgambaeva Asiya E. , Prud'homme Nathalie , Krisyuk Vladislav V. , Vahlas Constantin 
Published: July 2012

AbstractApplication of mass spectrometry (MS) for the investigation of metal‐organic (MO)CVD processes is demonstrated through the example of the deposition of copper films from copper(I) cyclopentadienyltriethylphosphine (CpCuPEt3). In‐situ MS, where a miniature hot‐wall CVD reactor built in the time‐of‐flight mass analyzer, is used to investigate the decomposition mechanism of the precursor during low‐pressure (LP) MOCVD. On line MS is used to explore the gas phase upon copper film production as a function of temperature in a cold‐wall MOCVD reactor operating under 10 Torr. The two MS techniques provide compatible information which illustrates the vapor behavior of the precursors on the growing surface, and correlates all changes in the composition of the gas phase with the growth rate of Cu films in any stage of the deposition process. In agreement with reported experimental results, a monotonic increase in the intensity of the precursor and a decrease in the intensity of the products are observed with deposition time at low deposition temperature, indicating a gradual decrease in the growth rate. This behavior is attributed to the saturation of the growing surface with adsorbed triethylphosphine which hinders precursor supply to the deposition zone. It is shown, through the example of the co‐deposition of Al‐Cu films from dimethylamine alane and CpCuPEt3, that there is no mutual interaction of the precursors in the gas phase.
A Comparative Study of the Properties of ZnO Nano/Microstructures Grown using Two Types of Thermal Evaporation Set‐Up Conditions
Authors: Yousefi Ramin , Jamali‐Sheini Farid , Zak Ali Khorsand 
Published: July 2012

AbstractZnO nano/microstructures are grown on Si(111) substrates using two types of thermal evaporation set‐up. The effects of thermal evaporation set‐up conditions and substrate temperature on the morphological and optical properties of ZnO nano/microstructures are investigated. Tubes with either one‐end open and one end sealed (OOE), or both ends open (TOE) are used as the objects that could change the conditions in a thermal evaporation set‐up. Observations show that, under similar source and substrate temperatures, such changes result in different shapes and sizes of ZnO structures. Room temperature photoluminescence (PL) and Raman spectroscopy (RS) studies demonstrate that the ZnO structures grown in the OOE tube have better crystalline quality and optical properties than those grown in the TOE tube. In fact, the results show that the morphology and crystalline qualities of the products can be controlled by the set‐up conditions.
High energy‐efficient and privacy‐preserving secure data aggregation for wireless sensor networks
Authors: Liu Chen‐Xu , Liu Yun , Zhang Zhen‐Jiang , Cheng Zi‐Yao 
Published: July 2012

SUMMARYAn efficient data process technology is needed for wireless sensor networks composed of many sensors with constrained communication, computational, and memory resources. Data aggregation is presented as an efficient and significant method to reduce transmitted data and prolong lifetime for wireless sensor networks. Meanwhile, many applications require preserving privacy for secure data aggregation. In this paper, we propose a high energy‐efficient and privacy‐preserving scheme for secure data aggregation. Because of the importance of communication overhead and accuracy, our scheme achieves less communication overhead and higher data accuracy besides providing for privacy preservation. For extensive simulations, we evaluate and conclude the performance of our high energy‐efficient and privacy‐preserving scheme. The conclusion shows that the high energy‐efficient and privacy‐preserving scheme provides better privacy preservation and is more efficient than existing schemes. Copyright © 2012 John Wiley & Sons, Ltd.
Solvothermal Synthesis of Uniform Co3O4/C Hollow Quasi‐Nanospheres for Enhanced Lithium Ion Intercalation Applications
Authors: Liu Jun , Wan Yanling , Liu Chunping , Liu Wei , Ji Shaomin , Zhou Yichun , Wang Jinbin 
Published: July 2012

AbstractNanostructured hollow electrodes can greatly improve the electrochemical performance of lithium ion batteries by reducing the diffusion distance for lithium ion transport, providing more freedom for volume change, which can reduce the overpotential and allow better reaction kinetics at the electrode surface. In this communication, we report the synthesis of carbon‐coated single‐crystalline Co3O4 porous and hollow quasi‐nanospheres by an in situ carbon‐coating and Ostwald ripening solvothermal process. The process of structure evolution from carbon‐coated solid nanocubes to porous and hollow quasi‐nanospheres was demonstrated with SEM and TEM images after different solvothermal reaction times. The carbon‐coated porous and hollow structure facilitates lithium ion transport from the electrolyte solution to the electrode, increases the electronic conductivity of the electrodes, which leads to the formation of uniform and thin solid electrolyte interphase (SEI) films on the surface, and maintains the integrity of the nanoparticles. As a result, these carbon‐coated Co3O4 porous and hollow quasi‐nanospheres exhibit good recyclability and high rate capability (629 and 256 mA h g–1 at 2 C and 15 C, respectively).
Complete Characterization of the 3D Properties of the CCR5 Antagonist Vicriviroc through DFT Calculations, NMR Spectroscopy, and X‐ray Analysis
Authors: Legnani Laura , Colombo Diego , Villa Stefania , Meneghetti Fiorella , Castellano Carlo , Gelain Arianna , Marinone Albini Franca , Toma Lucio 
Published: July 2012

AbstractVicriviroc is a piperazine‐based CCR5 receptor antagonist, with better oral availability, potency, safety, and pharmacological properties than those of its precursor SCH‐C, but whose development has been stopped. A full evaluation of the 3D properties of vicriviroc was carried out in order to achieve a complete knowledge of its conformational behavior and, consequently, to identify the parameters necessary to design new, possibly better, analogs. The theoretical study was performed at the B3LYP/6‐31G(d) level of calculations. Particular attention was focused on the arrangement at the planar amido function and the conformational preferences of the piperazine and piperidine rings. Several conformational families, characterized by different through‐space contacts and comparable energy values, were located and confirmed by high‐field NMR spectroscopy. Two distinct series of signals, originating from the barrier to rotation of the amido function, were observed in the NMR spectrum. Moreover, a NOESY experiment provided evidence for all the close contacts present assuring the coexistence, in solution, of numerous conformations in equilibrium, characterized by different chair geometries of the heterocyclic rings.