bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical Studies on the Dynamics of the Fluorine Atom Reaction withtrans-1,3-butadiene
Authors: Song Hui , Wang Xiu-yan , Yang Xue-ming
Published: January 2011

Theoretical studies of F atom reaction with trans-1,3-butadiene were carried out at the CCSD(T)/6-311G(d,p)/B3LYP/6-311G(d,p) levels. Energies and structures for all reactants, products and transition states were determined. Two reaction pathways involving the formation of the complexes CH2CHCHFCH2 and CH2CHCHCH2F were found in this reaction. Theoretical results suggest that the H atom channel observed in previous crossed beam experiment occurs likely via these two long-lived complex formation pathways. For the complex CH2CHCHFCH2 pathway, another reaction channel (C2H3+C2H3F) is also accessible. Relative importance of the C2H3+C2H3F channel versus the H formation channel via the same reaction pathway has also been estimated, suggesting that it would be diffcult to observe the C2H3+C2H3F channel in a crossed molecular beam experiment. Theoretical analysis also shows that the HF formation proceeds via direct abstraction mechanisms, though it is likely a minor process in this reaction.
Atomic Simulation of Structure and Deformation's Influence on the Mechanical Properties of Single-walled Carbon Nanotubes
Authors: Ni Xiang-gui , Wang Yu , Zhang Zhong , Wang Xiu-xi
Published: January 2011

Tensile deformation behaviors and the Poisson's ratio of single-walled carbon nanotubes (SWCNTs) are numerically studied, using the molecular dynamics (MD) method. Effects of several structural features of crystal cells of SWCNTs, i.e., the size, chirality and strain, on their mechanical properties are analyzed systematically. The simulations indicate that Armchair SWCNTs (8, 8)-(22, 22) and Zigzag SWCNTs (9,0)-(29,0) can be stretched by 35%-38% and 20%-27% without sign of plasticity, respectively. The Young's modulus of SWCNTs under tension ranges from 960 GPa to 750 GPa as their radii increase. The Young's modulus of zigzag SWCNTs is higher than that of armchair SWCNTs. Additionally, three SWCNTs (9,9), (12,6) and (16,0) are investigated to obtain their Poisson's ratio under tensile and compressive loading. The results show that the Poisson's ratio of nanotubes decreases generally as the strain increases. Under the same tensile strain, the Poisson's ratio decreases as the chiral angles of SWCNTs decrease, while their Poisson's ratios increase under the same compressive strain.
Ionic Conduction and Fuel Cell Performance of Ba0.97Ce0.8Ho0.2O3 Ceramic
Authors: Qiu Li-gan
Published: January 2011

The perovskite-type-oxide solid solution Ba0.97Ce0.8Ho0.2O3 was prepared by high temperature solid-state reaction and its single-phase character was confirmed by X-ray diffraction. The ionic conduction of the sample was investigated using electrical methods at elevated temperatures, and the performance of the hydrogen-air fuel cell using the sample as solid electrolyte was measured, which were compared with those of BaCe0.8Ho0.2O3. In wet hydrogen, BaCe0.8Ho0.2O3 almost exhibits pure protonic conduction at 600-1000 C, and its protonic transport number is 1 at 600-900 C and 0.99 at 1000 C. Similarly, Ba0.97Ce0.8Ho0.2O3 exhibits pure protonic conduction with the protonic transport number of 1 at 600-700 C, but its protonic conduction is slightly lower than that of BaCe0.8Ho0.2O3, and the protonic transport number are 0.99-0.96 at 800-1000 C. In wet air, the two samples both show low protonic and oxide ionic conduction. For Ba0.97Ce0.8Ho0.2O3, the protonic and oxide ionic transport numbers are 0.01-0.11 and 0.30-0.31 respectively, and for BaCe0.8Ho0.2O3, 0.01-0.09 and 0.27-0.33 respectively. Ionic conductivities of Ba0.97Ce0.8Ho0.2O3 are higher than those of BaCe0.8Ho0.2O3 under wet hydrogen and wet air. The performance of the fuel cell using Ba0.97Ce0.8Ho0.2O3 as solid electrolyte is better than that of BaCe0.8Ho0.2O3. At 1000 C, its maximum short-circuit current density and power output density are 465 mA/cm2 and 112 mW/cm2, respectively.
Effect of Ammonia Thermal Treatment on the Structure and Activity of Titanium Oxide Photocatalysts
Authors: Tang Yu-chao , Huang Xian-huai , Yu Han-qing , Hu Chun
Published: January 2011

Different titanium oxide powders (ATiO2, BTiO2) were pretreated in ammonia (NH3) gas at high temperatures. After the pretreatment, the color of the titanium oxide powders changed from white to yellow or gray depending on the pretreatment temperatures. Morphologies and structures of the treated titanium oxide powders were characterized by physical chemical methods. XRD measurements showed that the crystalline structures were mainly mixture of anatase and rutile for the ATiO2 but only anatase for the BTiO2. Stronger absorption of visible light was observed for both types of samples using UV-Vis diffuse reflectance spectra. X-ray photoelectron spectroscopy demonstrated that doped nitrogen existed on the surface TiO2 after ammonia gas pretreatment. The photocatalytic activities of the treated titanium oxide samples were evaluated via the photodegradation of methyl orange and phenol in aqueous suspensions. No obvious improvement in photocatalytic activity was achieved by ammonia pretreatment although it could enhance the absorption of light. Effects of treatment temperatures on photoactivities were complete different for ATiO2 and BTiO2 (i.e. higher treated temperatures yielded higher activities for BTiO2 but lower for ATiO2). All samples yielded lower activity levels after ammonia pretreatment without regard to pretreatment temperature or the reaction light resource.
Hydrogen-bonding Interaction of 1,2,3-triazine-waters Complexes
Authors: Li Quan , Huang Fang-qian , Hu Jing-dan , Zhao Ke-qing
Published: January 2011

Density functional theory B3LYP method with 6-31++G** basis was used to optimize the geometries of the ground states for 1,2,3-triazine-(H2O)n (n=1,2,3) complexes. All calculations indicate that the 1,2,3-triazine-water complexes in the ground states have strong hydrogen-bonding interaction, and the complex having a N HO hydrogen bond and a chain of water molecules which is terminated by a O HC hydrogen bond is the most stable. The HO stretching modes of complexes are red-shifted relative to that of the monomer. In addition, the Natural bond orbit (NBO) analysis indicates that the intermolecular charge transfer between 1,2,3-triazine and water is 0.0222e, 0.0261e and 0.0273e for the most stable 1:1, 1:2 and 1:3 complexes, respectively. The first singlet (n, *) vertical excitation energy of the monomer 1,2,3-triazine and the hydrogen-bonding complexes of 1,2,3-triazine-(H2O)n were investigated by time-dependent density functional theory.
Estimation of Saturated Vapor Pressure from Nucleation Data
Authors: Wang Mei-li , Yang Ji-ming , Luo Xi-sheng
Published: January 2011

Saturated vapor pressure was calculated from the nucleation experimental data using the thermodynamically consistent nucleation theory in which the effect of real gas is considered. The cubic polynomial fit equations of saturation pressure for several substances were obtained based on the calculation. The results of the calculations were compared to those of thermodynamic equilibrium equation and the empirical equation and applied to the predictions of the classical nucleation theory. The results show that the saturation pressures estimated from the nucleation data agree fairly well with those of empirical equations for the substances investigated, and this indicates that the predictions from the classical nucleation theory are close to the experimental data.
Spherical Micro-lens Array of PMMA Produced by Micro-molding
Authors: Zhu Jian-hua , Shi Jin-xia , Wang Yuan , He Ping-sheng
Published: January 2011

Micro-lens (ML) and Micro-lens array (MLA) are important optical components widely used in many fields; Soft-lithography, a vital little process technology, has its unique performance to produce ML and MLA; The cylinder and spherical MLA of polymethyl methacrylate (PMMA) were successfully obtained by micro-molding in Soft-lithography. Some suitable experimental parameters in the process were discussed, and the imaging property of the MLA was also studied simply.
Differential Interference Angle of Collision-induced Rotational Energy Transfer in Na2(A1u+,v=8 b30u,v=14)-Na System
Authors: Li Jian , Li Yong-qing , Wang Wei-li , Ma Feng-cai
Published: January 2011

Here we report calculation of the differential interference angles (including b and b) for singlet-triplet mixed states of Na2(A1u+, v=8 b30u, v=14)-Na system in collision with Na, in order to study the collision-induced quantum interference on rotational energy transfer in an atom-diatom system. The calculation is based on the first-order Born approximation of time-dependent perturbation theory, and the anisotropic Lennard-Jones interaction potentials are also employed. The relationships between differential interference angle and impact parameter, including collision diameter and velocity, are obtained.
Chemical Reaction and Energy Transfer Between Hot H Atoms and CO2 Molecules
Authors: Shi Cong-yun , Ren Li , Kong Fan-ao
Published: January 2011

Collisions between hot H atoms and CO2 molecules were studied experimentally by time-resolved Fourier transform infrared emission spectroscopy. H atoms with three translational energies, 174.7, 241.0 and 306.2 kJ/mol respectively, were generated by UV laser photolysis to initiate a chemical reaction of H+CO2OH+CO. Vibrationally excited CO (v2) was observed in the spectrum, where CO was the product of the reaction. The highly efficient T-V energy transfer from the hot H atoms to the CO2 was verified too. The highest vibrational level of v=4 in CO2 (v3) was found. Rate ratio of the chemical reaction to the energy transfer was estimated as 10.
Pseudo-capacitive Behavior of Cobalt Hydroxide/Carbon Nanotubes Composite Prepared by Cathodic Deposition
Authors: Wang Xiao-feng , Ruan Dian-bo , You Zheng
Published: January 2011

A novel type of composite electrode based on multiwalled carbon nanotubes coated with sheet-like cobalt hydroxide particles was used in supercapacitors. Cobalt hydroxide cathodically deposited from Co(NO3)2 solution with carbon nanotubes as matrix exhibited large pseudo-capacitance of 322 F/g in 1 mol/L KOH. To characterize the cobalt hydroxide nanocomposite electrode, a charge-discharge cycling test, cyclic voltammetry, and an impedance test were done. This cobalt hydroxide composite exhibiting excellent pseudo-capacitive behavior (i.e. high reversibility, high specific capacitance, low impedance), was demonstrated to be a candidate for the application of electrochemical supercapacitors. A combined capacitor consisting of cobalt hydroxide composite as a cathode and activated carbon fiber as an anode was reported. The electrochemical performance of the combined capacitor was characterized by cyclic voltammetry and a dc charge/discharge test. The combined capacitor showed ideal capacitor behavior with an extended operating voltage of 1.4 V. According to the extended operating voltage, the energy density of the combined capacitor at a current density of 100 mA/cm2 was found to be 11 Wh/kg. The combined capacitor exhibited high-energy density and stable power characteristics.
Crystal Structure of 8-Hydroxyeremophil-7(11)-ene-12,8(4,6)-diolide
Authors: Xue Hui-qing , Xue Hui-feng , Wu Biao , Wang Han-qing , Xin Xue-lei , Wu Shui-xian
Published: January 2011

8-Hydroxyeremophil-7(11)-ene-12,8(4,6)-diolide was isolated from the Ligularia intermedia and characterized by MS, multi NMR and X-ray single crystal diffraction. Its crystal structure was determined as in a orthorhombic type, with space group P212121 with a=6.8519(5), b=10.7191(8), c=18.5942(14) A, V =1365.67(18) A3, Z=4, and the calculated density is 1.354 mg/m3. F(000)=592, =0.101 mm1.
Growth and Spectral Properties of Nd3+:NaLa(WO4)2 Crystals
Authors: Chen Chi-lai , Hou Yong-sheng , Cai Wei-li , Yao Lian-zeng
Published: January 2011

Nd3+:NaLa(WO4)2 crystals with a dimension up to 7 mm were grown from a high temperature solution using a double-crucible method. Scanning electron microscopy observations of the crystals showed that there were no small cracks on the surface of the crystals although they underwent two phase transitions when cooling down from high temperatures. X-ray diffraction studies indicated that the as-obtained product is pure low-temperature tetragonal Nd3+:NaLa(WO4)2. The absorption and fluorescence spectra for Nd3+:NaLa(WO4)2 were measured at room temperature. The absorption band at 804 nm has a wide full-width half maximum of 23 nm whose origin is discussed. The absorption and emission cross sections were calculated to be 7.2410-20 cm2 at 804 nm and 6.5410-20 cm2 at 1057 nm, respectively.
Micromolding in Capillaries Using Swollen Elastomeric Stamp
Authors: Shi Jin-xia , Wang Zheng , He Ping-sheng , Yang Hai-yang
Published: January 2011

Micromolding in capillaries of a micro-square array was carried out for polystyrene solution in acetone by means of swollen polydimethylsiloxane (PDMS) elastomeric stamp. The resulting micro-cubic poles were isolated and separable when the added amount of the polystyrene solution was small. Some special distorting micro-patterns in the micro-square array were observed because of shrinkage resulting from the varying evaporation rate of solvent at different places.
Fabrication and Characterization of LiFePO4 Nanotubes by a Sol-gel-AAO Template Process
Authors: Liu Xiao-hong , Wang Jin-qing , Zhang Jun-yan , Yang Sheng-rong
Published: January 2011

The LiFePO4 nanotubes were successfully fabricated by a sol-gel method with porous anodic aluminum oxide as the template. Transmission electron microscopy and scanning electron microscopy showed that the synthesized LiFePO4 nanotubes were monodispersed and parallel to one another. Selected area electron diffraction pattern, X-ray diffraction and X-ray photoelectron spectroscopy investigations jointly demonstrated that the synthesized LiFePO4 nanotubes were pure olivine structure. This approach offered a potentially way for fabricating ordered LiFePO4 nanotubes at room temperature and ambient conditions, which might be expected to find promising application as a new cathode material in lithium ion battery.
Crystal Structure and Photocatalytic Characteristics of Nanoscale Sb-doped TiO2 Thin Films
Authors: Ren Da-sen , Zhang Zhuang-jian
Published: January 2011

Nanoscale Sb doped titanium dioxide thin films photocatalyst (Ti1-xSbO2) were obtained from dip-coating sol-gel method. The influence of dopant Sb density on the crystal structure and the phase transformation of the thin films were characterized by X-ray diffraction (XRD) and Raman spectra. The results of XRD showed that as-prepared films were not only in anatase state but also in brookite. The crystalline size was estimated to be around 13.3-20 nm. Raman spectra indicated there coexisted other phases and a transformation from brookite to anatase in the samples doped with 0.2% Sb. After doping a proper amount of Sb, the crystallization rate and the content of the anatase Ti1-xSbO2 in the thin films was clearly enhanced because Sb replaced part of the Ti of TiO2 in the thin films. The anode current density (photocurrent density) and the first order reaction speed constant (k) of thin films doped with 0.2% Sb reached 42.49 A/cm2 and 0.171 h/cm2 under 254 nm UV illumination, respectively, which is about 11 times and 2 times that of the non-doped TiO2 anode prepared by the same method respectively.
Light Sheet Fluorescence Microscopy
Authors: Santi Peter A.
Published: February 2011

Light sheet fluorescence microscopy (LSFM) functions as a non-destructive microtome and microscope that uses a plane of light to optically section and view tissues with subcellular resolution. This method is well suited for imaging deep within transparent tissues or within whole organisms, and because tissues are exposed to only a thin plane of light, specimen photobleaching and phototoxicity are minimized compared to wide-field fluorescence, confocal, or multiphoton microscopy. LSFMs produce well-registered serial sections that are suitable for three-dimensional reconstruction of tissue structures. Because of a lack of a commercial LSFM microscope, numerous versions of light sheet microscopes have been constructed by different investigators. This review describes development of the technology, reviews existing devices, provides details of one LSFM device, and shows examples of images and three-dimensional reconstructions of tissues that were produced by LSFM.
Genome-wide Gene Expression Profiling of Formalin-fixed Paraffin-Embedded Breast Cancer Core Biopsies Using Microarrays
Authors: Budczies Jan , Weichert Wilko , Noske Aurelia , Müller Berit Maria , Weller Claudia , Wittenberger Timo , Hofmann Hans-Peter , Dietel Manfred , Denkert Carsten , Gekeler Volker
Published: February 2011

The routine workflow for invasive cancer diagnostics includes biopsy processing by formalin fixation and paraffin embedding. It has been shown only recently that this kind of sample can be used for gene expression analysis with microarrays. To support this view, the authors conducted a microarray study using formalin-fixed paraffin-embedded (FFPE) core needle biopsies from breast cancers. Typically, for the 3′-biased chip type that was used, the probe sets interrogate sequences near the poly-A-tail of the transcripts, and this kind of probe turned out to be suitable to measure RNA levels in FFPE biopsies. For ER and HER2, the authors observed strong correlations between RNA levels and protein expression ( p = 0.000003 and p = 0.0022). ER and HER2 classification of the biopsies by the RNA levels was feasible with high sensitivity and specificity (AUROC = 0.93 and AUROC = 0.96). Furthermore, a signature of 346 genes was identified that correlated with ER and a signature of 528 genes that correlated with HER2 protein status. Many of these genes (ER: 63%) could be confirmed by analysis of gene expression data from frozen tissues. The findings support the notion that clinically relevant information can be gained from microarray analyses of FFPE cancer biopsies. This opens new opportunities for biomarker detection studies and the integration of microarrays into the workflow of cancer diagnostics.
Regulation of Brown Fat Adipogenesis by Protein Tyrosine Phosphatase 1B
Authors: Matsuo Kosuke , Bettaieb Ahmed , Nagata Naoto , Matsuo Izumi , Keilhack Heike , Haj Fawaz G.
Published: January 2011

Background

Protein-tyrosine phosphatase 1B (PTP1B) is a physiological regulator of insulin signaling and energy balance, but its role in brown fat adipogenesis requires additional investigation.

Methodology/Principal Findings

To precisely determine the role of PTP1B in adipogenesis, we established preadipocyte cell lines from wild type and PTP1B knockout (KO) mice. In addition, we reconstituted KO cells with wild type, substrate-trapping (D/A) and sumoylation-resistant (K/R) PTP1B mutants, then characterized differentiation and signaling in these cells. KO, D/A- and WT-reconstituted cells fully differentiated into mature adipocytes with KO and D/A cells exhibiting a trend for enhanced differentiation. In contrast, K/R cells exhibited marked attenuation in differentiation and lipid accumulation compared with WT cells. Expression of adipogenic markers PPARγ, C/EBPα, C/EBPδ, and PGC1α mirrored the differentiation pattern. In addition, the differentiation deficit in K/R cells could be reversed completely by the PPARγ activator troglitazone. PTP1B deficiency enhanced insulin receptor (IR) and insulin receptor substrate 1 (IRS1) tyrosyl phosphorylation, while K/R cells exhibited attenuated insulin-induced IR and IRS1 phosphorylation and glucose uptake compared with WT cells. In addition, substrate-trapping studies revealed that IRS1 is a substrate for PTP1B in brown adipocytes. Moreover, KO, D/A and K/R cells exhibited elevated AMPK and ACC phosphorylation compared with WT cells.

Conclusions

These data indicate that PTP1B is a modulator of brown fat adipogenesis and suggest that adipocyte differentiation requires regulated expression of PTP1B.
Growth patterns in free-ranging bank voles, Myodes glareolus (Schreber 1780) from a mountainous area in central Italy
Authors: Amori Giovanni , Luiselli Luca
Published: January 2011

Growth patterns are nearly unknown in free-ranging rodents. Here, we analyse growth patterns (in body length) in relation to sex, year and population density in a population of bank voles, Myodes glareolus, studied by the capture-mark-recapture method at a mountainous site in central Italy during a 12-year period. In our study, (i) male and female bank voles had very similar growth rates and growth trajectories as described by von Bertalanffy growth functions; (ii) growth rates strongly varied interannually; and (iii) growth rates were independent on population densities, i.e., there was no density-dependence mechanism following individual growth rates in bank voles. The general implications of these patterns are discussed.
Sphingolipid Storage Affects Autophagic Metabolism of the Amyloid Precursor Protein and Promotes Aβ Generation
Authors: Tamboli Irfan Y. , Hampel Heike , Tien Nguyen T. , Tolksdorf Karen , Breiden Bernadette , Mathews Paul M. , Saftig Paul , Sandhoff Konrad , Walter Jochen
Published: February 2011

Deposition of amyloid β peptides (Aβs) in extracellular amyloid plaques within the human brain is a hallmark of Alzheimer's disease (AD). Aβ derives from proteolytic processing of the amyloid precursor protein (APP) by β- and γ-secretases. The initial cleavage by β-secretase results in shedding of the APP ectodomain and generation of APP C-terminal fragments (APP-CTFs), which can then be further processed within the transmembrane domain by γ-secretase, resulting in release of Aβ. Here, we demonstrate that accumulation of sphingolipids (SLs), as occurs in lysosomal lipid storage disorders (LSDs), decreases the lysosome-dependent degradation of APP-CTFs and stimulates γ-secretase activity. Together, this results in increased generation of both intracellular and secreted Aβ. Notably, primary fibroblasts from patients with different SL storage diseases show strong accumulation of potentially amyloidogenic APP-CTFs. By using biochemical, cell biological, and genetic approaches, we demonstrate that SL accumulation affects autophagic flux and impairs the clearance of APP-CTFs. Thus, accumulation of SLs might not only underlie the pathogenesis of LSDs, but also trigger increased generation of Aβ and contribute to neurodegeneration in sporadic AD.
What Does Local Functional Hyperemia Tell about Local Neuronal Activation?
Authors: Jukovskaya Natalya , Tiret Pascale , Lecoq Jérôme , Charpak Serge
Published: February 2011

In the brain, neuronal activation triggers a local increase in cerebral blood flow, a response named functional hyperemia. The extent to which functional hyperemia faithfully reports brain activation, spatially or temporally, remains a matter of debate. Here, we used the olfactory bulb glomerulus as a neurovascular model and two-photon microscopy imaging to investigate the correlation between calcium signals in glutamatergic terminals of olfactory sensory neurons and local vascular responses. We find that, depending on odor stimulation intensity, vascular responses are differently coupled to calcium signals. Upon moderate odor stimulation, glomerular vascular responses increase accordingly with calcium signals. In contrast, in silent glomeruli neighboring strongly activated ones and in glomeruli adapting upon high odor stimulation, vascular responses are independent of or negatively coupled to presynaptic calcium signals, respectively. Hence, functional hyperemia, a key signal used in functional imaging, can be, at times, an unreliable marker of local brain activation.
Leptin-Receptor-Expressing Neurons in the Dorsomedial Hypothalamus and Median Preoptic Area Regulate Sympathetic Brown Adipose Tissue Circuits
Authors: Zhang Yan , Kerman Ilan A. , Laque Amanda , Nguyen Phillip , Faouzi Miro , Louis Gwendolyn W. , Jones Justin C. , Rhodes Chris , Münzberg Heike
Published: February 2011

Brown adipose tissue (BAT) thermogenesis is critical to maintain homoeothermia and is centrally controlled via sympathetic outputs. Body temperature and BAT activity also impact energy expenditure, and obesity is commonly associated with decreased BAT capacity and sympathetic tone. Severely obese mice that lack leptin or its receptor (LepRb) show decreased BAT capacity, sympathetic tone, and body temperature and thus are unable to adapt to acute cold exposure (Trayhurn et al., 1976). LepRb-expressing neurons are found in several hypothalamic sites, including the dorsomedial hypothalamus (DMH) and median preoptic area (mPOA), both critical sites to regulate sympathetic, thermoregulatory BAT circuits. Specifically, a subpopulation in the DMH/dorsal hypothalamic area (DHA) is stimulated by fever-inducing endotoxins or cold exposure (Dimicco and Zaretsky, 2007; Morrison et al., 2008). Using the retrograde, transsynaptic tracer pseudorabies virus (PRV) injected into the BAT of mice, we identified PRV-labeled LepRb neurons in the DMH/DHA and mPOA (and other sites), thus indicating their involvement in the regulation of sympathetic BAT circuits. Indeed, acute cold exposure induced c-Fos (as a surrogate for neuronal activity) in DMH/DHA LepRb neurons, and a large number of mPOA LepRb neurons project to the DMH/DHA. Furthermore, DMH/DHA LepRb neurons (and a subpopulation of LepRb mPOA neurons) project and synaptically couple to rostral raphe pallidus neurons, consistent with the current understanding of BAT thermoregulatory circuits from the DMH/DHA and mPOA (Dimicco and Zaretsky, 2007; Morrison et al., 2008). Thus, these data present strong evidence that LepRb neurons in the DMH/DHA and mPOA mediate thermoregulatory leptin action.
Human Basal Ganglia and the Dynamic Control of Force during On-Line Corrections
Authors: Grafton Scott T. , Tunik Eugene
Published: February 2011

Natural movements are corrected in part by the generation of submovements, occurring early in a movement such that they amend an ongoing action. Submovements are associated with activity of the basal ganglia, implying a role for the structures in error correction. In parallel, the basal ganglia are linked to the generation and control of force amplitude, change, and duration. Here, we tested whether activity in human basal ganglia is associated with submovements generally, or was specific to a condition where the submovements only occurred in the face of unexpected proprioceptive error. Submovements were induced by introducing unexpected and variable viscous loads (augmenting the need for trial-specific grip forces) or by reducing target size (augmenting the need for visually guided on-line control) in a one-dimensional target-capture task. In both cases, subjects compensated for the increased task difficulty by generating corrective submovements, which were closely matched in frequency and type. Activity in the internal segment of the globus pallidus and subthalamic nucleus correlated strongly with the number of submovements during the viscous challenge but not with the target challenge. The effects could not be explained by kinematic differences, i.e., movement amplitude or average number of submovements. The results support a specific role for the basal ganglia in error correction under conditions of variable load where there is a need for the dynamic control of force within an ongoing movement.
Sleep Selectively Enhances Memory Expected to Be of Future Relevance
Authors: Wilhelm Ines , Diekelmann Susanne , Molzow Ina , Ayoub Amr , Mölle Matthias , Born Jan
Published: February 2011

The brain encodes huge amounts of information, but only a small fraction is stored for a longer time. There is now compelling evidence that the long-term storage of memories preferentially occurs during sleep. However, the factors mediating the selectivity of sleep-associated memory consolidation are poorly understood. Here, we show that the mere expectancy that a memory will be used in a future test determines whether or not sleep significantly benefits consolidation of this memory. Human subjects learned declarative memories (word paired associates) before retention periods of sleep or wakefulness. Postlearning sleep compared with wakefulness produced a strong improvement at delayed retrieval only if the subjects had been informed about the retrieval test after the learning period. If they had not been informed, retrieval after retention sleep did not differ from that after the wake retention interval. Retention during the wake intervals was not affected by retrieval expectancy. Retrieval expectancy also enhanced sleep-associated consolidation of visuospatial (two-dimensional object location task) and procedural motor memories (finger sequence tapping). Subjects expecting the retrieval displayed a robust increase in slow oscillation activity and sleep spindle count during postlearning slow-wave sleep (SWS). Sleep-associated consolidation of declarative memory was strongly correlated to slow oscillation activity and spindle count, but only if the subjects expected the retrieval test. In conclusion, our work shows that sleep preferentially benefits consolidation of memories that are relevant for future behavior, presumably through a SWS-dependent reprocessing of these memories.
Horizontal Cell Feedback without Cone Type-Selective Inhibition Mediates “Red–Green” Color Opponency in Midget Ganglion Cells of the Primate Retina
Authors: Crook Joanna D. , Manookin Michael B. , Packer Orin S. , Dacey Dennis M.
Published: February 2011

The distinctive red–green dimension of human and nonhuman primate color perception arose relatively recently in the primate lineage with the appearance of separate long (L) and middle (M) wavelength-sensitive cone photoreceptor types. “Midget” ganglion cells of the retina use center–surround receptive field structure to combine L and M cone signals antagonistically and thereby establish a “red–green, color-opponent” visual pathway. However, the synaptic origin of red–green opponency is unknown, and conflicting evidence for either random or L versus M cone-selective inhibitory circuits has divergent implications for the developmental and evolutionary origins of trichromatic color vision. Here we directly measure the synaptic conductances evoked by selective L or M cone stimulation in the midget ganglion cell dendritic tree and show that L versus M cone opponency arises presynaptic to the midget cell and is transmitted entirely by modulation of an excitatory conductance. L and M cone synaptic inhibition is feedforward and thus occurs in phase with excitation for both cone types. Block of GABAergic and glycinergic receptors does not attenuate or modify L versus M cone antagonism, discounting both presynaptic and postsynaptic inhibition as sources of cone opponency. In sharp contrast, enrichment of retinal pH-buffering capacity, to attenuate negative feedback from horizontal cells that sum L and M cone inputs linearly and without selectivity, completely abolished both the midget cell surround and all chromatic opponency. Thus, red–green opponency appears to arise via outer retinal horizontal cell feedback that is not cone type selective without recourse to any inner retinal L versus M cone inhibitory pathways.
Thermoregulatory Phenotype of theTrpv1Knockout Mouse: Thermoeffector Dysbalance with Hyperkinesis
Authors: Garami Andras , Pakai Eszter , Oliveira Daniela L. , Steiner Alexandre A. , Wanner Samuel P. , Almeida M. Camila , Lesnikov Vladimir A. , Gavva Narender R. , Romanovsky Andrej A.
Published: February 2011

This study aimed at determining the thermoregulatory phenotype of mice lacking transient receptor potential vanilloid-1 (TRPV1) channels. We usedTrpv1knockout (KO) mice and their genetically unaltered littermates to study diurnal variations in deep body temperature (Tb) and thermoeffector activities under basal conditions, as well as thermoregulatory responses to severe heat and cold. Only subtle alterations were found in the basalTbofTrpv1KO mice or in theirTbresponses to thermal challenges. The main thermoregulatory abnormality ofTrpv1KO mice was a different pattern of thermoeffectors used to regulateTb. On the autonomic side,Trpv1KO mice were hypometabolic (had a lower oxygen consumption) and hypervasoconstricted (had a lower tail skin temperature). In agreement with the enhanced skin vasoconstriction,Trpv1KO mice had a higher thermoneutral zone. On the behavioral side,Trpv1KO mice preferred a lower ambient temperature and expressed a higher locomotor activity. Experiments with pharmacological TRPV1 agonists (resiniferatoxin and anandamide) and a TRPV1 antagonist (AMG0347) confirmed that TRPV1 channels located outside the brain tonically inhibit locomotor activity. With age (observed for up to 14 months), the body mass ofTrpv1KO mice exceeded that of controls, sometimes approaching 60 g. In summary,Trpv1KO mice possess a distinct thermoregulatory phenotype, which is coupled with a predisposition to age-associated overweight and includes hypometabolism, enhanced skin vasoconstriction, decreased thermopreferendum, and hyperkinesis. The latter may be one of the primary deficiencies inTrpv1KO mice. We propose that TRPV1-mediated signals from the periphery tonically suppress the general locomotor activity.
Wnt Signaling Regulates Neuronal Differentiation of Cortical Intermediate Progenitors
Authors: Munji Roeben N. , Choe Youngshik , Li Guangnan , Siegenthaler Julie A. , Pleasure Samuel J.
Published: February 2011

Cortical intermediate progenitors (IPs) comprise a secondary neuronal progenitor pool that arises from radial glia (RG). IPs are essential for generating the correct number of cortical neurons, but the factors that regulate the expansion and differentiation of IPs in the embryonic cortex are essentially unknown. In this study, we show that the Wnt–β-catenin pathway (canonical Wnt pathway) regulates IP differentiation into neurons. Upregulation of Wnt–β-catenin signaling by overexpression of Wnt3a in the neocortex induced early differentiation of IPs into neurons and the accumulation of these newly born neurons at the subventricular zone/intermediate zone border. Long-term overexpression of Wnt3a led to cortical dysplasia associated with the formation of large neuronal heterotopias. Conversely, downregulation of Wnt–β-catenin signaling with Dkk1 during mid and late stages of neurogenesis inhibited neuronal production. Consistent with previous reports, we show that Wnt–β-catenin signaling also promotes RG self-renewal. Thus, our findings show differential effects of the Wnt–β-catenin pathway on distinct groups of cortical neuronal progenitors: RG self-renewal and IP differentiation. Moreover, our findings suggest that dysregulation of Wnt signaling can lead to developmental defects similar to human cortical malformation disorders.
Heparan Sulphate Proteoglycan and the Low-Density Lipoprotein Receptor-Related Protein 1 Constitute Major Pathways for Neuronal Amyloid-β Uptake
Authors: Kanekiyo Takahisa , Zhang Juan , Liu Qiang , Liu Chia-Chen , Zhang Lijuan , Bu Guojun
Published: February 2011

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disorder in which the aggregation and deposition of amyloid-β (Aβ) peptides in the brain are central to its pathogenesis. In healthy brains, Aβ is effectively metabolized with little accumulation. Cellular uptake and subsequent degradation of Aβ is one of the major pathways for its clearance in the brain. Increasing evidence has demonstrated significant roles for the low-density lipoprotein receptor-related protein 1 (LRP1) in the metabolism of Aβ in neurons, glia cells, and along the brain vasculatures. Heparan sulfate proteoglycan (HSPG) has also been implicated in several pathogenic features of AD, including its colocalization with amyloid plaques. Here, we demonstrate that HSPG and LRP1 cooperatively mediate cellular Aβ uptake. Fluorescence-activated cell sorter and confocal microscopy revealed that knockdown of LRP1 suppresses Aβ uptake, whereas overexpression of LRP1 enhances this process in neuronal cells. Heparin, which antagonizes HSPG, significantly inhibited cellular Aβ uptake. Importantly, treatment with heparin or heparinase blocked LRP1-mediated cellular uptake of Aβ. We further showed that HSPG is more important for the binding of Aβ to the cell surface than LRP1. The critical roles of HSPG in cellular Aβ binding and uptake were confirmed in Chinese hamster ovary cells genetically deficient in HSPG. We also showed that heparin and a neutralizing antibody to LRP1 suppressed Aβ uptake in primary neurons. Our findings demonstrate that LRP1 and HSPG function in a cooperative manner to mediate cellular Aβ uptake and define a major pathway through which Aβ gains entry to neuronal cells.
Antiferromagnetic behavior in Y–Ba–(Cu1−xScx)–O
Authors: Chakraborty A. , Chen X. D. , Zuo F. , Patton B. R. , Gaines J. R. , Epstein A. J.
Published: February 2011

We report the results on x-ray diffraction and magnetic susceptibility study of Y–Ba–(Cu1−xScx)–O. The materials were prepared in a stoichiometry corresponding to Y1Ba2(Cu1−xScx)3O7. Although x-ray analysis reveals the increasing presence of a subtle second phase with increasing Sc content, the superconducting transition temperature and resistivity did not change substantially in the composition range 0.0  x ≤ 0.15. In contrast, the magnetic susceptibility studies showed dramatic changes. Although Sc3+ has no spin by itself, an enhanced paramagnetic Curie susceptibility was observed above Tc with a moment of 1.5 μB per Sc. At 16 K a sharp cusp is observed in the temperature dependent susceptibility corresponding to the onset of a three-dimensionally ordered antiferromagnetic state. These results are discussed in terms of an additional previously unreported phase of Y–Ba–(Cu–Sc)–O that has an antiferromagnetic Néel temperature of 16 K. For composition of x = 1.0, a new phase is formed which is nonmagnetic.
Solid Electrolytes: Advances in Science and Technology
Authors: Jain Himanshu , Thomas John O. , Whittingham M. Stanley
Published: February 2011

The interdisciplinary area of science and engineering dealing with solid electrolytes and mixed conductors is frequently known as solid-state ionics. It concerns materials that show rapid ionic motion with or without electronic conductivity, from basic science through application. Interest in solid-state ionic materials has continued for the past few decades due to several important, promising applications, such as fuel cells, batteries, sensors, and electrochemical pumps. The principle behind these applications is simply either the Nernst law (as exemplified by Equation 1 in the article by Singhal in this issue) or Faraday's laws of electrochemistry (which connect current flow to mass flow), as applied to a cell consisting of an electrolyte and two electrodes. However, the technological issues are complex, and demands on materials can be very diverse, as illustrated by the five articles in this issue. These articles are based, in part, on the invited talks presented at a symposium in April 1999 on the same subject at Lehigh University to commemorate G.C. Farrington's inauguration as its president.
Integrated Fabrication Processes for Solid-Oxide Fuel Cells Using Thermal Plasma Spray Technology
Authors: Gitzhofer François , Boulos Maher , Heberlein Joachim , Henne Rudolf , Ishigaki Takamasa , Yoshida Toyonobu
Published: February 2011

In the manufacture of solid-oxide fuel cells (SOFCs), thermal-plasma technology, especially plasma spraying, offers several advantages, the most important of which is the ability to achieve considerably higher deposition rates than those that can be obtained with such approaches as physical or chemical vapor deposition (PVD or CVD). This article describes an international collaborative research project partially funded by NEDO (New Energy and Industrial Technology Development Organization, Japan) and carried out at five research laboratories around the world: at the University of Tokyo and National Institute for Research in Inorganic Materials (NIRIM) in Japan, the University of Minnesota in the United States, the University of Sherbrooke in Canada, and DLR—Stuttgart in Germany. The objective of the project was to conduct a comparative study on the possible use of four thermal-plasma spraying techniques for the integrated fabrication of SOFCs.
Toward Commercialization of the Beta-Alumina Family of Ionic Conductors
Authors: Sudworth J. L. , Barrow P. , Dong W. , Dunn B. , Farrington G. C. , Thomas J. O.
Published: February 2011

The beta-alumina family of materials has played a central role in the field of solid-state ionics. β- and β-alumina have been a principal theme in the field ever since Yao and Kummer reported the extraordinarily high conductivity for sodium β-alumina. The material “came of age” at a time when there was great interest in the science and technology of highconductivity solid electrolytes. A previous MRS Bulletin review introduced this broad family of materials, examining the range of compositions and the two major structures. The beta-alumina family emerged as almost an ideal system in which to explore structure-property relations, as its unusual structure is responsible for its remarkable ion-transport properties. Although the initial interest in this material, and the one which endures to this day, is its rapid sodium-ion transport, the rich ion-exchange chemistry added a dimension to this material that few inorganic systems can match, let alone exceed. β-alumina, in particular, is an almost universal solid electrolyte for cations. It constitutes a broad family of solid electrolytes whose properties are dependent upon the nature of the ion inserted into the conduction plane. As a result, the β-aluminas have served as model systems for a wide range of studies: proton transport and mixed-ion diffusion, order-disorder reactions, and superlattice phenomena. Moreover, these β-alumina compositions demonstrated that fast-ion transport was not limited to a few monovalentions, but could be extended to divalent and even trivalent cations. With the latter materials, the interest was not necessarily ion transport, but optical properties instead. The presence of trivalent cations in this unusual structure, coupled with the ability to control the chemistry of the local environment, enabled the β-aluminas to exhibit a number of novel optical properties.
Applications and Processing of Transparent Conducting Oxides
Authors: Lewis Brian G. , Paine David C.
Published: February 2011

The first report of a transparent conducting oxide (TCO) was published in 1907, when Badeker reported that thin films of Cd metal deposited in a glow discharge chamber could be oxidized to become transparent while remaining electrically conducting. Since then, the commercial value of these thin films has been recognized, and the list of potential TCO materials has expanded to include, for example, Al-doped ZnO, GdInOx, SnO2, F-doped In2O3, and many others. Since the 1960s, the most widely used TCO for optoelectronic device applications has been tin-doped indium oxide (ITO). At present, and likely well into the future, this material offers the best available performance in terms of conductivity and transmissivity, combined with excellent environmental stability, reproducibility, and good surface morphology. The use of other TCOs in large quantities is application-specific. For example, tin oxide is now widely used in architectural glass applications.
Chemical and Thin-Film Strategies for New Transparent Conducting Oxides
Authors: Freeman A. J. , Poeppelmeier K. R. , Mason T. O. , Chang R. P. H. , Marks T. J.
Published: February 2011

Transparent conducting oxides (TCOs) have been known and employed technologically for more than 50 years, primarily in the form of doped single-cation oxides such as In2O3 and SnO2. Beginning in the 1990s, however, multi-cation oxide TCOs began to be developed in Japan (see the article by Minami in this issue and the references therein) and at the former Bell Laboratories. Since then, new TCO phases are being reported with increasing frequency as technological interest in this area heightens. At the same time, our fundamental understanding of the chemical and structural origins of transparent conductivity continues to expand and promises a pathway to dramatically improved materials for a host of applications. This article describes a collaborative, multi-investigator bulk an d thin-film research effort at Northwestern University aimed at the synthesis, characterization, and enhanced understanding of multi-cation (compound and solidsolution) TCOs, and provides a brief account of what we are discovering about this important class of materials.
Soft Solution Processing: A Strategy for One-Step Processing of Advanced Inorganic Materials
Authors: Yoshimura Masahiro , Suchanek Wojciech L. , Byrappa Kullaiah
Published: February 2011

The term “materials cycle” is generally used to describe the synthesis of substances from raw materials (sometimes including the synthesis of manufactured raw materials), the fabrication of shaped materials, their use, and their eventual disposal. It is well known that all materials are extracted from the earth, then are converted to functional products through various fabrication processes, usually involving a high expenditure of energy, which in turn contributes to environmental problems such as global warming.
Three-Dimensional Network-Structured Cyanide-Based Magnets
Authors: Miller Joel S.
Published: February 2011

Magnets based on metal oxides have been important for hundreds of years. Magnetite, Fe3O4, Co-doped γ-Fe2O3, and CrO2 are important examples. The oxide (O2-) bridge between the magnetic metal ions has filled p orbitals (Figure 1a) that provide the pathway for strong spin coupling. Albeit with twice as many atoms, cyanide (C≡N−) can bridge between two metal ions via its pair of empty antibonding orbitals (Figure 1b) and filled nonbonding orbitals. Even prior to a detailed understanding of either their composition or structure, magnetic ordering of several cyanide complexes, although at low temperature, was noted. The differing atoms at each end of the cyanide ion have different binding affinities to metal ions, and simple coordination compounds, for example, [FeII(CN)6]2− (ferrocyanide), with alkali cations can easily be made. Replacement of the alkali cations with transition-metal cations affords insoluble materials, for example FeIII4[FeII(CN)6]3 (Prussian blue). Prussian blue has been used as a pigment and as an electrochromic and electrocatalyst material. The structure of Prussian blue was elucidated to be cubic (isotropic) with ⟶FeII⟵C≡N⟶FeIII⟵N≡C⟶FeII⟵ linkages along all three crystallographic directions (Figure 2). The FeII … FeIII separation is ∼5 Å. However, based on the composition, this is an idealized structure, as one FeII site per unit cell is missing. Water fills the vacant sites as well as the channels present in the structure. Due to the structural defects, it has been a challenge to grow single crystals.
Supramolecular Materials
Authors: Moore Jeffrey S.
Published: February 2011

This issue of MRS Bulletin is devoted to the subject of supramolecular materials. The term supramolecular is widely used to describe the intentional use of noncovalent interactions to bring about a desired arrangement of molecules. As the articles in this issue illustrate, this type of molecular engineering can provide structural control on the nanoscale and beyond, broadly impacting the properties of the resulting materials. The goal is to create a collection of molecules in which the whole possesses characteristics that are different and unattainable from the individual components.
Supramolecular Polymers
Authors: Brunsveld Luc , Folmer Brigitte J. B. , Meijer E. W.
Published: February 2011

What started as a scientific challenge roughly 10 years ago has become a technological reality today, as materials from supramolecular polymers and their many applications as smart materials have emerged. Synthetic polymeric materials are among the most important classes of new materials introduced in the 20th century. They are primarily used for construction, but electronic and biomedical applications are also at the forefront of science and technology.