bluuebunny/crossref_metadata_2025 huggingface dataset:
Silver‐Catalysed Enantioselective Addition of OH and NH Bonds to Allenes: A New Model for Stereoselectivity Based on Noncovalent Interactions
Authors: Arbour Jannine L. , Rzepa Henry S. , Contreras‐García Julia , Adrio Luis A. , Barreiro Elena M. , Hii King Kuok (Mimi)
Published: July 2012

The ability of silver complexes to catalyse the enantioselective addition of OH and NH bonds to allenes is demonstrated for the first time by using optically active anionic ligands that were derived from oxophosphorus(V) acids as the sources of chirality. The intramolecular addition of acids, alcohols, and amines to allenes can be achieved with up to 73 % ee. The exploitation of a CH anomeric effect allowed the absolute configuration of a sample of 2‐substituted tetrahydrofuran of low ee to be unambiguously assigned by comparison of the chiroptical ORD and VCD measurements with calculated spectra. In the second part of the work, the origin of the stereoselectivity was probed by DFT free‐energy calculations of the transition states. A new model of enantiomeric differentiation was developed that was based on noncovalent interactions. This model allowed us to identify the source of stereoselectivity as weak attractive interactions; such dispersive forces are often overlooked in asymmetric catalysis. A new computational approach was developed that represents these interactions as colour‐coded isosurfaces that are characterised by the reduced density‐gradient profile.
Asymmetric Inverse‐Electron‐Demand Hetero‐Diels–Alder Reaction for the Construction of Bicyclic Skeletons with Multiple Stereocenters by Using a Bifunctional Organocatalytic Strategy: An Efficient Approach to Chiral Macrolides
Authors: Jiang Xianxing , Wang Long , Kai Ming , Zhu Liping , Yao Xiaojun , Wang Rui
Published: July 2012

We have performed the first bifunctional organocatalytic highly enantioselective inverse‐electron‐demand hetero‐Diels–Alder reaction of cyclic ketones with enones to afford densely functionalized bicyclic skeletons that contain three stereocenters (up 82 % yield, 10:1 d.r., and 97 % ee). Unlike the previous IEDDAR catalytic strategy, this method features a double HOMOdienophile/ LUMOdiene‐activated pathway. Moreover, this process provides a promising method for the construction of enantioenriched macrolides.
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

We 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

New 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

The 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

A 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

Synthesis 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

Asymmetric 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

Receiver 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

This 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

The 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

The 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

This 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

In 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

Application 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

ZnO 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

An 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

Nanostructured 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

Vicriviroc 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.
Electrochemical Determination of Inorganic Contaminants in Automotive Fuels
Authors: Santos André L. , Takeuchi Regina M. , Muñoz Rodrigo A. A. , Angnes Lúcio , Stradiotto Nelson R.
Published: July 2012

This article critically reviews the electroanalytical methods developed for the determination of inorganic contaminants in automotive fuels. Topics include the methods applied to the analysis of liquid biofuels and liquid fossil fuels for which different strategies were developed based on analytes and sample matrices. Special attention is given to electrodes, detection techniques, and sample preparation protocols (when required). Analytes include anions such as chloride, sulfate and phosphate, and mainly metallic species such as sodium, potassium, magnesium, calcium, cadmium, copper, iron, lead, manganese, mercury, nickel, platinum, tin, vanadium, and zinc. Suggestions for future research are also presented.
Comparison of the Effects of Biofouling on Voltammetric and Potentiometric Measurements
Authors: Kuhlmann Julia , Dzugan Laura C. , Heineman William R.
Published: July 2012

Biofouling of sensors is a common problem when measuring biological samples. The adherence of proteins and biomolecules, called hemostasis, is the first of four steps that lead to biofouling and eventually a foreign body response. This typically occurs within the first hours after the exposure of the biosensor to a biological sample. The purpose of this study was to assess the effect of this initial step of biofouling on cyclic voltammetry and potentiometric measurements. The results show that biofouling occurred rapidly within minutes and strongly affected cyclic voltammetry measurements, while potentiometric measurements were minimally affected even after 24 hours.
Toxic effects of PCB126 and TCDD on shortnose sturgeon and Atlantic sturgeon
Authors: Chambers R. Christopher , Davis Dawn D. , Habeck Ehren A. , Roy Nirmal K. , Wirgin Isaac
Published: July 2012

Exposure to chemical contaminants is often invoked to explain recruitment failures to populations of sturgeon worldwide, but there is little empirical evidence to support the idea that young sturgeon are sensitive at environmentally relevant concentrations. The authors used shortnose sturgeon (Acipenser brevirostum) and Atlantic sturgeon (Acipenser oxyrinchus) as models to investigate the sensitivities of sturgeon to early-life-stage toxicities from embryonic exposures to graded doses of polychlorinated biphenyl 126 (PCB126) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Survival to hatching of shortnose sturgeon decreased with increasing dose, although the duration of the embryonic period was not significantly altered by exposure in either species. Morphometric features of larvae of both species were affected by dose, including shortening of the body, reduction in head size, reduction in quantity of yolk reserves, and reduction in eye size. Eye development in both species was delayed with increasing dose for both chemicals. The persistence of larvae in a food-free environment decreased inversely with dose in both species, with sharp declines occurring at PCB126 and TCDD doses of ≥1 ppb and ≥0.1 ppb, respectively. Dose-responsive early-life-stage toxicities reported here are among the more sensitive found in fish and occurred at burdens similar to those found in situ in a sympatric bottom-dwelling bony fish in the Hudson River Estuary. The present study is among the first demonstrating the sensitivity of any sturgeon to the hallmark early-life-stage toxicities induced by aryl hydrocarbon receptor agonists. Environ. Toxicol. Chem. 2012; 31: 2324–2337. © 2012 SETAC
Biomarkers of exposure and effect in a lacertid lizard (Podarcis bocagei Seoane) exposed to chlorpyrifos
Authors: Amaral Maria José , Sanchez-Hernandez Juan C. , Bicho Rita C. , Carretero Miguel A. , Valente Ricardo , Faustino Augusto M.R. , Soares Amadeu M.V.M. , Mann Reinier M.
Published: July 2012

In Europe, reptiles have been recently included in environmental risk-assessment processes for registration of plant-protection products. However, data on toxicity effects of most compounds are lacking. Chlorpyrifos is the most commonly used organophosphorus insecticide worldwide. In the present study, the authors exposed a lacertid lizard, Podarcis bocagei, to sublethal concentrations of chlorpyrifos. Individuals were exposed through spiked food for a period of 20 d (low dose 0.12 mg/kg/d, high dose 1.57 mg/kg/d). After exposure, various biomarkers of exposure and effect were evaluated, including the activities of glutathione S-transferase and enzymes involved in the glutathione redox cycle, glutathione concentrations, activities of esterases, liver and testes histopathologies, as well as locomotory and predatory behavior. The results indicate that sublethal, subchronic exposure to chlorpyrifos can affect P. bocagei in a dose-dependent manner. Adverse effects occurred at both the subindividual and individual levels, including inhibition of carboxylesterases and cholinesterases (ChEs), liver histopathological changes, and altered predatory behaviors. Animals exposed to chlorpyrifos took more time to capture and subdue prey items. The results suggest a link between effects at subindividual levels of organization with those observed at the whole individual level after exposure to environmentally realistic dosages of chlorpyrifos. Environ. Toxicol. Chem. 2012; 31: 2345–2353. © 2012 SETAC
A new TVD method for advection simulation on 2D unstructured grids
Authors: Hou J. , Simons F. , Hinkelmann R.
Published: July 2012

For advection schemes with flux limiters derived on one‐dimensional grids to two‐dimensional (2D) unstructured triangular ones. In this method, the variables located normal to this face are taken into more account to compute the flux, by means of defining required nodes along the line through the center point of the considered face and perpendicular to it. Besides, the new method adopts the improved total variation diminishing schemes in, which consider the face position between the two neighboring cells as well as the size differences of the related cells; therefore, it fits 2D unstructured grids well. Compared with the present flux limiting methods for 2D unstructured grids, a higher accuracy and efficiency and a good monotonicity are achieved by the new method.Copyright © 2012 John Wiley & Sons, Ltd.
A numerical investigation of a spectral‐type nodal collocation discontinuous Galerkin approximation of the Euler and Navier–Stokes equations
Authors: Bassi F. , Franchina N. , Ghidoni A. , Rebay S.
Published: July 2012

In this paper, we focus on the applicability of spectral‐type collocation discontinuous Galerkin methods to the steady state numerical solution of the inviscid and viscous Navier–Stokes equations on meshes consisting of curved quadrilateral elements. The solution is approximated with piecewise Lagrange polynomials based on both Legendre–Gauss and Legendre–Gauss–Lobatto interpolation nodes. For the sake of computational efficiency, the interpolation nodes can be used also as quadrature points. In this case, however, the effect of the nonlinearities in the equations and/or curved elements leads to aliasing and/or commutation errors that may result in inaccurate or unstable computations. By a thorough numerical testing on a set of well known test cases available in the literature, it is here shown that the two sets of nodes behave very differently, with a clear advantage of the Legendre–Gauss nodes, which always displayed an accurate and robust behaviour in all the test cases considered.Copyright © 2012 John Wiley & Sons, Ltd.
Co‐Firing with biomass can keep coal plants operating
Authors: Johnson Bill
Published: July 2012

Facing a myriad of state greenhouse gas (GHG) emission and renewable energy regulations and an absence of comprehensive federal energy policy, many in the energy industry are attempting to develop their own approach for energy security and environmental stewardship. A cornerstone of the industry's efforts is trying to anticipate the capital requirements likely necessary to comply with existing and potential regulations addressing GHG issues and various renewable energy objectives. Without policy certainty, these tasks are both complex and costly.
Electric transmission: Challenges of interconnecting renewable resources to the transmission grid
Authors: Sunderman Derek
Published: July 2012

The development of utility‐scale renewable projects (USRPs) is fraught with challenges and potential pitfalls that even experienced project development and utility professionals can find difficult to manage. These challenges include issues related to the environment, funding, equipment procurement, and transmission access.
Natural gas—International: China to supply huge natural gas growth
Authors: Clemente Jude
Published: July 2012

As the projected fastest‐growing fossil fuel through 2030, natural gas is viewed as the “bridge” source to a more sustainable energy future. Combusted gas emits 30 percent less carbon dioxide (CO2) than oil and 45 percent less than coal and has lower levels of nitrogen oxides, sulfur dioxide, and particulate matter.
Electric regulation: Utilities undertaking smart grid investment should use benchmarking techniques
Authors: Bowden Nicholas S.
Published: July 2012

In the simplest of terms, the regulator's goal is twofold: ensure utility solvency while inducing the utility to provide quality service at a price that reflects productive efficiency. The ostensible goal of Smart Grid investment is to increase the quality of service, while a likely outcome is the increase in the price needed to ensure utility solvency. Given the uncertainty about the efficacy of Smart Grid investment, public utility regulators would be prudent to undertake benchmarking studies that ensure that improvements in quality explain any increase in utility expenses that result in higher prices.
The Deposition and Chronology of Cenote T’isil: A Multiproxy Study of Human/Environment Interaction in the Northern Maya Lowlands of Southeast Mexico
Authors: Wollwage Lance , Fedick Scott , Sedov Sergey , Solleiro‐Rebolledo Elizabeth
Published: July 2012

Cenotes (natural wells or sinkholes) comprise the most common landscape features in the northern Maya Lowlands of the Yucatán Peninsula, México. Detailed study of dated soil‐sedimentary sequences, recovered from a cenote at the archaeological site T’isil and nearby wetlands, allows a partial reconstruction of environmental variability at the site for the last 2000 years. Biogenic calcite sedimentation and Calcisol development occur during three intervals of increased inundation in cenote and wetland environments, ca. A.D. 300, A.D. 1000, and A.D. 1300. Periods of increased inundation in the cenote and wetlands correlate with wetter climatic intervals, and periods of Maya occupation at sites in the Yalahau region. Evidence for Maya modification of the cenote environment may relate to regional wetland agricultural practices.
The “quad‐partite” synapse: Microglia‐synapse interactions in the developing and mature CNS
Authors: Schafer Dorothy P. , Lehrman Emily K. , Stevens Beth
Published: July 2012

Microglia are the resident immune cells and phagocytes of our central nervous system (CNS). While most work has focused on the rapid and robust responses of microglia during CNS disease and injury, emerging evidence suggests that these mysterious cells have important roles at CNS synapses in the healthy, intact CNS. Groundbreaking live imaging studies in the anesthetized, adult mouse demonstrated that microglia processes dynamically survey their environment and interact with other brain cells including neurons and astrocytes. More recent imaging studies have revealed that microglia dynamically interact with synapses where they appear to serve as “synaptic sensors,” responding to changes in neural activity and neurotransmitter release. In the following review, we discuss the most recent work demonstrating that microglia play active roles at developing and mature synapses. We first discuss the important imaging studies that have led us to better understand the physical relationship between microglia and synapses in the healthy brain. Following this discussion, we review known molecular mechanisms and functional consequences of microglia‐synapse interactions in the developing and mature CNS. Our current knowledge sheds new light on the critical functions of these mysterious cells in synapse development and function in the healthy CNS, but has also incited several new and interesting questions that remain to be explored. We discuss these open questions, and how the most recent findings in the healthy CNS may be related to pathologies associated with abnormal and/or loss of neural circuits. © 2012 Wiley Periodicals, Inc.
Liver grafts from CD39-overexpressing rodents are protected from ischemia reperfusion injury due to reduced numbers of resident CD4+ T cells
Authors: Pommey Sandra , Lu Bo , McRae Jennifer , Stagg John , Hill Prue , Salvaris Evelyn , Robson Simon C. , d'Apice Anthony J.F. , Cowan Peter J. , Dwyer Karen M.
Published: July 2012

Ischemia-reperfusion injury (IRI) is a major limiting event for successful liver transplantation, and CD4+ T cells and invariant natural killer T (iNKT) cells have been implicated in promoting IRI. We hypothesized that hepatic overexpression of CD39, an ectonucleotidase with antiinflammatory functions, will protect liver grafts after prolonged cold ischemia. CD39-transgenic (CD39tg) and wildtype (WT) mouse livers were transplanted into WT recipients after 18 hours cold storage and pathological analysis was performed 6 hours after transplantation. Serum levels of alanine aminotransferase and interleukin (IL)-6 were significantly reduced in recipients of CD39tg livers compared to recipients of WT livers. Furthermore, less severe histopathological injury was demonstrated in the CD39tg grafts. Immune analysis revealed that CD4+ T cells and iNKT cells were significantly decreased in number in the livers of untreated CD39tg mice. This was associated with a peripheral CD4+ T cell lymphopenia due to defective thymocyte maturation. To assess the relative importance of liver-resident CD4+ T cells and iNKT cells in mediating liver injury following extended cold preservation and transplantation, WT mice depleted of CD4+ T cells or mice genetically deficient in iNKT cells were used as donors. The absence of CD4+ T cells, but not iNKT cells, protected liver grafts from early IRI.

Conclusion

: Hepatic CD4+ T cells, but not iNKT cells, play a critical role in early IRI following extended cold preservation in a liver transplant model.
RhoE is frequently down-regulated in hepatocellular carcinoma (HCC) and suppresses HCC invasion through antagonizing the Rho/Rho-Kinase/Myosin phosphatase target pathway
Authors: Ma Wei , Wong Carmen Chak-Lui , Tung Edmund Kwok-Kwan , Wong Chun Ming , Ng Irene Oi-Lin
Published: July 2012

Deregulation of Rho guanosine triphosphatase (GTPase) pathways plays an important role in tumorigenesis and metastasis of hepatocellular carcinoma (HCC). RhoE/Rnd3 belongs to an atypical subfamily of the RhoGTPase, the Rnd family, as it lacks the intrinsic GTPase activity and remains always in its active GTP-bound form. In this study we investigated the role of RhoE in HCC. We examined the expression of RhoE in primary HCC samples from patients predominantly infected with the hepatitis B virus (HBV) and found that the RhoE messenger RNA (mRNA) level was frequently down-regulated (83.1%, 59/71) in HCCs. Low expression of RhoE in the tumors was significantly associated with shorter disease-free survival (P = 0.020) of the patients. Knockdown of RhoE by short-hairpin RNA using a lentiviral approach led to increased cell motility and invasiveness in SMMC7721 and BEL7402 HCC cells. Moreover, in vivo an orthotopic liver injection model in nude mice further demonstrated that knockdown of RhoE enhanced local invasion of HCC cells in the livers, with more invasive tumor front and increased incidence of venous invasion. Mechanistically, stable knockdown of RhoE in HCC cells significantly enhanced the phosphorylation of myosin phosphatase, promoted assembly of stress fibers, and increased the formation of plasma membrane blebbings, all these changes and activities being associated with activation of the Rho/Rho-kinase (ROCK) pathway. Conclusion: RhoE was frequently down-regulated in predominantly HBV-associated HCCs and this down-regulation was associated with a more aggressive HCC phenotype. RhoE regulated the cytoskeleton remodeling and suppressed HCC motility and invasiveness by way of inhibiting the Rho/ROCK axis. (Hepatology 2013)
Detection of recombinant growth hormone by evanescent cascaded waveguide coupler on silica‐on‐silicon
Authors: Ozhikandathil Jayan , Packirisamy Muthukumaran
Published: July 2012

An evanescent wave based biosensor is developed on the silica‐on‐silicon (SOS) with a cascaded waveguide coupler for the detection of recombinant growth hormone. So far, U ‐bends and tapered waveguides are demonstrated for increasing the penetration depth and enhancing sensitivity of the evanescent wave sensor. In this work, a monolithically integrated sensor platform containing a cascaded waveguide coupler with optical power splitters and combiners designed with S ‐bends and tapper waveguides is demonstrated for an enhanced detection of recombinant growth hormone. In the cascaded waveguide coupler, a large surface area to bind the antibody with increased penetration depth of evanescent wave to excite the tagged‐rbST is obtained by splitting the waveguide into multiple paths using Y splitters designed with s ‐bends and subsequently combining them back to a single waveguide through tapered waveguide and combiners. Hence a highly sensitive fluoroimmunoassay sensor is realized. Using the 2D FDTD (Finite‐difference time‐domain method) simulation of waveguide with a point source in Rsoft FullWAVE, the fluorescence coupling efficiency of straight and bend section of waveguide is analyzed. The sensor is demonstrated for the detection of fluorescently‐tagged recombinant growth hormone with the detection limit as low as 25 ng/ml. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Folate‐conjugated thermo‐responsive micelles for tumor targeting
Authors: Zhang Jian , Deng Dawei , Zhu Hongyan , Byun Youngro , Yang Victor C. , Gu Yueqing
Published: July 2012

Folate‐conjugated and thermo‐responsive poly((N‐isopropylacrylamide)‐co‐ acrylamide‐co‐(octadecyl acrylate)‐co‐(folate‐(polyethylene glycol)‐(acrylic acid))) (P(NIPA‐co‐AAm‐co‐ODA‐co‐FPA)) micelles with mean diameter of about 60 nm and lower critical solution temperature (LCST) of about 39°C were synthesized by free radical random copolymerization. Single‐factor tests of acrylamide and octadecyl acrylate were carried out to modulate micelles' LCST and diameter, respectively. LCST, diameter, and morphology of micelles were determined by UV–vis spectrophotometer, laser particle size analyzer, and transmittance electron microscope (TEM), respectively. Fluorescein was then used as a model drug to investigate the drug loading content of micelles. Micelles with maximum amount of octadecyl acrylate (180 mg) were found to yield drug loading content of 10.48%. Near infrared dye No.10 was chosen as the tracer to monitor micelles in vivo. The targeting behaviors of micelles in folate receptor positive Bel‐7402 tumor bearing nude mice were assessed by a self‐constructed near infrared imaging system. Results showed satisfactory targeting capability of the thermo‐responsive micelles toward Bel‐7402 tumors, and targeting accumulation could last for more than 96 h, enabling P(NIPA‐co‐AAm‐co‐ODA‐co‐FPA) micelles to function as a diagnostic reagent as well as a targeted tumor therapy. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:3134–3142, 2012.
Development of a mechanically tuneable 3D scaffold for vascular reconstruction
Authors: Rodriguez Maritza , Juran Cassandra , McClendon Mark , Eyadiel Cyril , McFetridge Peter S.
Published: July 2012

Material compliance has been shown to be a predictor of vascular graft patency and as such is a critical parameter when designing new materials. Although ex vivo derived materials have been clinically successful in a number of applications their mechanical properties are a direct function of the original vessel and are not easily controllable. These investigations describe an approach to modulate the mechanical properties of an ex vivo derived scaffold by machining variable (discrete) wall thicknesses to control compliance. Human umbilical arteries (HUAs) were machine lathed directly from the umbilical cord at wall thicknesses of 250, 500, 750, and 1000 μm then decellularized using 1% sodium dodecyl sulfate. Compliance over physiological pressures, increased from 3.08 ± 1.84% to 11.47 ± 4.11% as direct function of each discrete vessel diameter. Radial stress strain analysis revealed primary and secondary failure points attributed to the discrete layers within the anisotropic scaffold. Maximum strength and suture retention were shown to increase with increasing wall thickness, by contrast stress failure decreased with increasing thickness due to increasing proportions of the mechanically weaker amorphous Wharton's jelly. Reseeded smooth muscle cells were shown to adhere, proliferate, and migrate from the scaffold surface showing the potential of the HUA as a mechanically “tunable” material with applications as an acellular implant or as a tissue engineered construct. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:3189–3196, 2012.