bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultra-thin gold films on transparent polymers
Authors: Leosson Kristjan , Ingason Arni S. , Agnarsson Bjorn , Kossoy Anna , Olafsson Sveinn , Gather Malte C.
Published: January 2013

Fabrication of continuous ultra-thin gold films (<10 nm) on the surface of optical polymers (CYCLOTENE and ORMOCLEAR) is reported. Using a range of electrical, optical and structural characterization techniques, we show that polymers can be superior to more conventional (inorganic) materials as optical substrates for realizing ultra-thin gold films. Using these transparent polymer substrates, smooth, patternable gold films can be fabricated with conventional deposition techniques at room temperature, without adhesion or seeding layers, facilitating new photonic and plasmonic nanostructures, including transparent electrical contacts, thin film waveguides, metamaterials, biosensors and high-contrast superlenses.
An LED-induced fluorescence detection system with integrated on-chip lens based on microfluidic chips technology/Ein LED-induziertes Fluoreszenzdetektionssystem mit integrierter „Lens-on-Chip“ basierend auf der mikrofluidischen Chiptechnologie
Authors: Zhao Yingying , Li Qin , Hu Xiao-Ming , Yang Dong-Fang
Published: January 2013

The power density of optical excitation on microfluidic chips is attenuated due to the beam divergence of the optical fiber, making it difficult to collect either the emission or scattering light. The excitation power and coupling efficiency can be significantly increased by using an on-chip microlens system with integrated optical fibers, specially designed and simulated to reshape and collect the optical signal within the microfluidic chip.

This article presents research work for designing, fabricating, and testing a type of on-chip microlens. The on-chip microlens was designed by Code V

The export light beam could be focused to a very small point to satisfy the requirements of the fluorescence excitation of samples. On the other hand, the detection efficiency could also be increased with the help of the on-chip microlens. The presented fabrication method does not require any assembly process or external driving force. To fabricate a microlens with a different focus, it is only necessary to change the figures on the mask. This technique can be used in a variety of applications as it is possible to produce customized microlens for specific applications.
Preparation and characterization of poly(2-hydroxyethyl methacrylate)/ Na-montmorillonite intercalated nanocomposites
Authors: Koç Zafer , Çelik Meltem , Önal Müşerref , Sarıkaya Yüksel , Mogulkoc Yesim
Published: January 2013

A series of intercalated nanocomposites were prepared via in situ polymerization of 2-hydroxyethyl methacrylate (HEMA) between the interlayer spacing of hydrous Na-montmorillonite (Na-MMT) using benzoyl peroxide (Bz2O2) as a radical initiator. X-ray diffraction patterns showed the absence of any intercalation up to 61.7 mass% of HEMA, but anhydrous Na-MMT formed by the hydrophilic effect of HEMA. The interlayer spacing (d001) values of hydrous and anhydrous Na-MMT were calculated as 1.19 and 1.03 nm, respectively. At higher monomer contents, the increase in the value of d001 from 1.19 to 2.01 nm indicated intercalation of polymer in the interlayer spacing of Na-MMT. Besides, transmission electron microscopy results supported the formation of the intercalated nanocomposites. Thermogravimetric analysis showed that the thermal stability of the nanocomposites increased considerably by intercalation of pure poly-HEMA. Specific surface area and specific nanopore volume of the nanocomposites decreased with the increasing of the monomer content taken by the preparations. The decrease is due to the nonporous nature of the polymer matrix.
Drying of polyacrylamide-multiwalled carbon nanotube (MWNT) composites with various MWNTs contents: a fluorescence study
Authors: Evingür Gülşen Akın , Pekcan Önder
Published: January 2013

We studied the drying of polyacrylamide (PAAm)-multiwalled carbon nanotube (MWNT) composites, prepared by free radical crosslinking copolymerization in water, with a steady state fluorescence technique. Composite gels were prepared at room temperature with pyranine (Py) doped as a fluorescence probe. Drying experiments were performed in air at various MWNT contents by real time monitoring of the Py fluorescence intensity (I) which increased as the drying proceeded. The Stern-Volmer equation, combined with the moving boundary diffusion model, was used to explain the behavior of I during drying. It was observed that the desorption coefficient (D) increased as the temperature increased. Drying energies (ΔE) were measured for the drying processes for each MWNT content gel, by using fluorescence, gravimetrical and volumetric methods. It is understood that ΔE values decrease by increasing MWNT content, until 1 wt% MWNT, and then increase above the level of this threshold value. The energy of drying is strongly correlated with the MWNT content in the composite. ΔE drops to its lowest value, at which conducting cluster starts to appear.
Study on thermal properties of polyurethane-urea elastomers prepared with different dianiline chain extenders
Authors: Barikani Majid , Fazeli Naghmeh , Barikani Mehdi
Published: January 2013

A number of polyurethane prepolymers based on polycaprolactone diol (PCL) and 4,4′-diphenyl methane diisocyanate (MDI) were synthesized and extended with different dianilines such as: 4,4′-methylenebis(2,6-diisopropylaniline) (M-DIPA), 4,4′-methylenebis(2,6diethylaniline) (M-DEA), 4,4′-methylenebis(ortho chloroaniline) (MOCA), 4,4′-methylenebis(2-isopropyl-6-methylaniline) (M-MIPA) and 4,4′-methylenebis(3-chloro-2,6-diethylaniline) (M-CDEA). Infrared (IR) spectroscopy was used to check the end of the polymerization reaction in addition to the polymer characterization. The effect of the dianiline structure on the thermal properties of the cast films were studied through dynamic mechanical measurements (DMTA), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. It was found that the thermal properties and thermal stability of polyurethane are strongly affected by the molecular structure of the dianiline chain extender.
Oral Administration of a Small Molecule Targeted to Block proNGF Binding to p75 Promotes Myelin Sparing and Functional Recovery after Spinal Cord Injury
Authors: Tep Chhavy , Lim Tae Hee , Ko Pyung On , Getahun Sami , Ryu Jae Cheon , Goettl Virginia M. , Massa Stephen M. , Basso Michele , Longo Frank M. , Yoon Sung Ok
Published: January 2013

The lack of effective therapies for spinal cord injury points to the need for identifying novel targets for therapeutic intervention. Here we report that a small molecule, LM11A-31, developed to block proNGF-p75 interaction and p75-mediated cell death crosses the blood–brain barrier efficiently when delivered orally. Administered starting 4 h postinjury, LM11A-31 promotes functional recovery without causing any toxicity or increased pain in a mouse model of spinal contusion injury. In both weight-bearing open-field tests and nonweight-bearing swim tests, LM11A-31 was effective in improving motor function and coordination. Such functional improvement correlated with a >50% increase in the number of surviving oligodendrocytes and myelinated axons. We also demonstrate that LM11A-31 indeed inhibits proNGF-p75 interactionin vivo, thereby curtailing the JNK3-mediated apoptotic cascade. These results thus highlight p75 as a novel therapeutic target for an orally delivered treatment for spinal cord injury.
Neuronal Basic Helix–Loop–Helix Proteins Neurod2/6 Regulate Cortical Commissure Formation before Midline Interactions
Authors: Bormuth Ingo , Yan Kuo , Yonemasu Tomoko , Gummert Maike , Zhang Mingyue , Wichert Sven , Grishina Olga , Pieper Alexander , Zhang Weiqi , Goebbels Sandra , Tarabykin Victor , Nave Klaus-Armin , Schwab Markus H.
Published: January 2013

Establishment of long-range fiber tracts by neocortical projection neurons is fundamental for higher brain functions. The molecular control of axon tract formation, however, is still poorly understood. Here, we have identified basic helix–loop–helix (bHLH) transcription factorsNeurod2andNeurod6as key regulators of fasciculation and targeted axogenesis in the mouse neocortex. InNeurod2/6double-mutant mice, callosal axons lack expression of the cell adhesion molecule Contactin2, defasciculate in the subventricular zone, and fail to grow toward the midline without forming Probst bundles. Instead, mutant axons overexpress Robo1 and follow random trajectories into the ipsilateral cortex. In contrast to long-range axogenesis, generation and maintenance of pyramidal neurons and initial axon outgrowth are grossly normal, suggesting that these processes are under distinct transcriptional control. Our findings define a new stage in corpus callosum development and demonstrate that neocortical projection neurons require transcriptional specification by neuronal bHLH proteins to execute an intrinsic program of remote connectivity.
Accelerated High-Yield Generation of Limb-Innervating Motor Neurons from Human Stem Cells
Authors: Amoroso Mackenzie W. , Croft Gist F. , Williams Damian J. , O'Keeffe Sean , Carrasco Monica A. , Davis Anne R. , Roybon Laurent , Oakley Derek H. , Maniatis Tom , Henderson Christopher E. , Wichterle Hynek
Published: January 2013

Human pluripotent stem cells are a promising source of differentiated cells for developmental studies, cell transplantation, disease modeling, and drug testing. However, their widespread use even for intensely studied cell types like spinal motor neurons is hindered by the long duration and low yields of existing protocols forin vitrodifferentiation and by the molecular heterogeneity of the populations generated. We report a combination of small molecules that within 3 weeks induce motor neurons at up to 50% abundance and with defined subtype identities of relevance to neurodegenerative disease. Despite their accelerated differentiation, motor neurons expressed combinations of HB9, ISL1, and column-specific markers that mirror those observedin vivoin human embryonic spinal cord. They also exhibited spontaneous and induced activity, and projected axons toward muscles when grafted into developing chick spinal cord. Strikingly, this novel protocol preferentially generates motor neurons expressing markers of limb-innervating lateral motor column motor neurons (FOXP1+/LHX3−). Access to high-yield cultures of human limb-innervating motor neuron subtypes will facilitate in-depth study of motor neuron subtype-specific properties, disease modeling, and development of large-scale cell-based screening assays.
Gestational Stress Promotes Pathological Apneas and Sex-Specific Disruption of Respiratory Control Development in Newborn Rat
Authors: Fournier Stéphanie , Steele Shelby , Julien Cécile , Fournier Sébastien , Gulemetova Roumiana , Caravagna Céline , Soliz Jorge , Bairam Aida , Kinkead Richard
Published: January 2013

Recurrent apneas are important causes of hospitalization and morbidity in newborns. Gestational stress (GS) compromises fetal brain development. Maternal stress and anxiety during gestation are linked to respiratory disorders in newborns; however, the mechanisms remain unknown. Here, we tested the hypothesis that repeated activation of the neuroendocrine response to stress during gestation is sufficient to disrupt the development of respiratory control and augment the occurrence of apneas in newborn rats. Pregnant dams were displaced and exposed to predator odor from days 9 to 19 of gestation. Control dams were undisturbed. Experiments were performed on male and female rats aged between 0 and 4 d old. Apnea frequency decreased with age but was consistently higher in stressed pups than controls. At day 4, GS augmented the proportion of apneas with O2desaturations by 12%. During acute hypoxia (12% O2), the reflexive increase in breathing augmented with age; however, this response was lower in stressed pups. Instability of respiratory rhythm recorded from medullary preparations decreased with age but was higher in stressed pups than controls. GS reduced medullary serotonin (5-HT) levels in newborn pups by 32%. Bath application of 5-HT and injection of 8-OH-DPAT [(±)-8-hydroxy-2-di-(n-propylamino) tetralin hydrobromide; 5-HT1Aagonist;in vivo] reduced respiratory instability and apneas; these effects were greater in stressed pups than controls. Sex-specific effects were observed. We conclude that activation of the stress response during gestation is sufficient to disrupt respiratory control development and promote pathological apneas in newborn rats. A deficit in medullary 5-HT contributes to these effects.
Influence of Core Auditory Cortical Areas on Acoustically Evoked Activity in Contralateral Primary Auditory Cortex
Authors: Carrasco Andres , Brown Trecia A. , Kok Melanie A. , Chabot Nicole , Kral Andrej , Lomber Stephen G.
Published: January 2013

In contrast to numerous studies of transcallosal communication in visual and somatosensory cortices, the functional properties of interhemispheric connections between auditory cortical fields have not been widely scrutinized. Therefore, the purpose of the present investigation was to measure the magnitude and type (inhibitory/excitatory) of modulatory properties of core auditory fields on contralateral primary auditory cortex (A1) activity. We combined single-unit neuronal recordings with reversible cooling deactivation techniques to measure variations in contralateral A1 response levels during A1, anterior auditory field (AAF), or simultaneous A1 and AAF neuronal discharge suppression epochs in cat auditory cortex. Cortical activity was evoked by presentation of pure tones, noise bursts, and frequency-modulated (FM) sweeps before, during, and after cortical deactivation periods. Comparisons of neuronal response changes before and during neuronal silencing revealed three major findings. First, deactivation of A1 and AAF-induced significant peak response reductions in contralateral A1 activity during simple (tonal) and complex (noise bursts and FM sweeps) acoustic exposure. Second, decreases in A1 neuronal activity appear to be in agreement with anatomical laminar termination patterns emanating from contralateral auditory cortex fields. Third, modulatory properties of core auditory areas lack hemispheric lateralization. These findings demonstrate that during periods of acoustic exposure, callosal projections emanating from core auditory areas modulate A1 neuronal activity via excitatory inputs.
RIM3γ and RIM4γ Are Key Regulators of Neuronal Arborization
Authors: Alvarez-Baron Elena , Michel Katrin , Mittelstaedt Tobias , Opitz Thoralf , Schmitz Frank , Beck Heinz , Dietrich Dirk , Becker Albert J. , Schoch Susanne
Published: January 2013

The large isoforms of the Rab3 interacting molecule (RIM) family, RIM1α/β and RIM2α/β, have been shown to be centrally involved in mediating presynaptic active zone function. The RIM protein family contains two additional small isoforms, RIM3γ and RIM4γ, which are composed only of the RIM-specific C-terminal C2B domain and varying N-terminal sequences and whose function remains to be elucidated. Here, we report that both, RIM3γ and RIM4γ, play an essential role for the development of neuronal arborization and of dendritic spines independent of synaptic function. γ-RIM knock-down in rat primary neuronal cultures andin vivoresulted in a drastic reduction in the complexity of neuronal arborization, affecting both axonal and dendritic outgrowth, independent of the time point of γ-RIM downregulation during dendrite development. Rescue experiments revealed that the phenotype is caused by a function common to both γ-RIMs. These findings indicate that γ-RIMs are involved in cell biological functions distinct from the regulation of synaptic vesicle exocytosis and play a role in the molecular mechanisms controlling the establishment of dendritic complexity and axonal outgrowth.
Synchronization of Medial Temporal Lobe and Prefrontal Rhythms in Human Decision Making
Authors: Guitart-Masip Marc , Barnes Gareth R. , Horner Aidan , Bauer Markus , Dolan Raymond J. , Duzel Emrah
Published: January 2013

Optimal decision making requires that we integrate mnemonic information regarding previous decisions with value signals that entail likely rewards and punishments. The fact that memory and value signals appear to be coded by segregated brain regions, the hippocampus in the case of memory and sectors of prefrontal cortex in the case of value, raises the question as to how they are integrated during human decision making. Using magnetoencephalography to study healthy human participants, we show increased theta oscillations over frontal and temporal sensors during nonspatial decisions based on memories from previous trials. Using source reconstruction we found that the medial temporal lobe (MTL), in a location compatible with the anterior hippocampus, and the anterior cingulate cortex in the medial wall of the frontal lobe are the source of this increased theta power. Moreover, we observed a correlation between theta power in the MTL source and behavioral performance in decision making, supporting a role for MTL theta oscillations in decision-making performance. These MTL theta oscillations were synchronized with several prefrontal sources, including lateral superior frontal gyrus, dorsal anterior cingulate gyrus, and medial frontopolar cortex. There was no relationship between the strength of synchronization and the expected value of choices. Our results indicate a mnemonic guidance of human decision making, beyond anticipation of expected reward, is supported by hippocampal–prefrontal theta synchronization.
Retrograde Bone Morphogenetic Protein Signaling Shapes a Key Circadian Pacemaker Circuit
Authors: Gorostiza E. Axel , Ceriani M. Fernanda
Published: January 2013

The neuropeptide pigment-dispersing factor (PDF) synchronizes molecular oscillations within circadian pacemakers in theDrosophilabrain. It is expressed in the small ventral lateral neurons (sLNvs) and large ventral lateral neurons, the former being indispensable for maintaining behavioral rhythmicity under free-running conditions. How PDF circuits develop the specific connectivity traits that endow such global behavioral control remains unknown. Here, we show that mature sLNv circuits require PDF signaling during early development, acting through its cognate receptor PDFR at postsynaptic targets. Yet, axonal defects by PDF knockdown are presynaptic and become apparent only after metamorphosis, highlighting a delayed response to a signal released early on. Presynaptic expression of constitutively active bone morphogenetic protein (BMP) receptors preventspdfrmutants misrouting phenotype, while sLNv-restricted downregulation of BMP signaling components phenocopiedpdf01. Thus, we have uncovered a novel mechanism that provides an early “tagging” of synaptic targets that will guide circuit refinement later in development.
Global Dysrhythmia of Cerebro-Basal Ganglia–Cerebellar Networks Underlies Motor Tics following Striatal Disinhibition
Authors: McCairn Kevin W. , Iriki Atsushi , Isoda Masaki
Published: January 2013

Motor tics, a cardinal symptom of Tourette syndrome (TS), are hypothesized to arise from abnormalities within cerebro-basal ganglia circuits. Yet noninvasive neuroimaging of TS has previously identified robust activation in the cerebellum. To date, electrophysiological properties of cerebellar activation and its role in basal ganglia-mediated tic expression remain unknown. We performed multisite, multielectrode recordings of single-unit activity and local field potentials from the cerebellum, basal ganglia, and primary motor cortex using a pharmacologic monkey model of motor tics/TS. Following microinjections of bicuculline into the sensorimotor putamen, periodic tics occurred predominantly in the orofacial region, and a sizable number of cerebellar neurons showed phasic changes in activity associated with tic episodes. Specifically, 64% of the recorded cerebellar cortex neurons exhibited increases in activity, and 85% of the dentate nucleus neurons displayed excitatory, inhibitory, or multiphasic responses. Critically, abnormal discharges of cerebellar cortex neurons and excitatory-type dentate neurons mostly preceded behavioral tic onset, indicating their central origins. Latencies of pathological activity in the cerebellum and primary motor cortex substantially overlapped, suggesting that aberrant signals may be traveling along divergent pathways to these structures from the basal ganglia. Furthermore, the occurrence of tic movement was most closely associated with local field potential spikes in the cerebellum and primary motor cortex, implying that these structures may function as a gate to release overt tic movements. These findings indicate that tic-generating networks in basal ganglia mediated tic disorders extend beyond classical cerebro-basal ganglia circuits, leading to global network dysrhythmia including cerebellar circuits.
Organization of Cortical and Thalamic Input to Pyramidal Neurons in Mouse Motor Cortex
Authors: Hooks Bryan M. , Mao Tianyi , Gutnisky Diego A. , Yamawaki Naoki , Svoboda Karel , Shepherd Gordon M. G.
Published: January 2013

Determining how long-range synaptic inputs engage pyramidal neurons in primary motor cortex (M1) is important for understanding circuit mechanisms involved in regulating movement. We used channelrhodopsin-2-assisted circuit mapping to characterize the long-range excitatory synaptic connections made by multiple cortical and thalamic areas onto pyramidal neurons in mouse vibrissal motor cortex (vM1). Each projection innervated vM1 pyramidal neurons with a unique laminar profile. Collectively, the profiles for different sources of input partially overlapped and spanned all cortical layers. Specifically, orbital cortex (OC) inputs primarily targeted neurons in L6. Secondary motor cortex (M2) inputs excited neurons mainly in L5B, including pyramidal tract neurons. In contrast, thalamocortical inputs from anterior motor-related thalamic regions, including VA/VL (ventral anterior thalamic nucleus/ventrolateral thalamic nucleus), targeted neurons in L2/3 through L5B, but avoided L6. Inputs from posterior sensory-related thalamic areas, including POm (posterior thalamic nuclear group), targeted neurons only in the upper layers (L2/3 and L5A), similar to inputs from somatosensory (barrel) cortex. Our results show that long-range excitatory inputs target vM1 pyramidal neurons in a layer-specific manner. Inputs from sensory-related cortical and thalamic areas preferentially target the upper-layer pyramidal neurons in vM1. In contrast, inputs from OC and M2, areas associated with volitional and cognitive aspects of movements, bypass local circuitry and have direct monosynaptic access to neurons projecting to brainstem and thalamus.
Neurogenesis Continues in the Third Trimester of Pregnancy and Is Suppressed by Premature Birth
Authors: Malik Sabrina , Vinukonda Govindaiah , Vose Linnea R. , Diamond Daniel , Bhimavarapu Bala B. R. , Hu Furong , Zia Muhammad T. , Hevner Robert , Zecevic Nada , Ballabh Praveen
Published: January 2013

Premature infants exhibit neurodevelopmental delay and reduced growth of the cerebral cortex. However, the underlying mechanisms have remained elusive. Therefore, we hypothesized that neurogenesis in the ventricular and subventricular zones of the cerebral cortex would continue in the third trimester of pregnancy and that preterm birth would suppress neurogenesis. To test our hypotheses, we evaluated autopsy materials from human fetuses and preterm infants of 16–35 gestational weeks (gw). We noted that both cycling and noncycling Sox2+radial glial cells and Tbr2+intermediate progenitors were abundant in human preterm infants until 28 gw. However, their densities consistently decreased from 16 through 28 gw. To determine the effect of premature birth on neurogenesis, we used a rabbit model and compared preterm [embryonic day 29 (E29), 3 d old] and term (E32, <2 h old) pups at an equivalent postconceptional age. Glutamatergic neurogenesis was suppressed in preterm rabbits, as indicated by the reduced number of Tbr2+intermediate progenitors and the increased number of Sox2+radial glia. Additionally, hypoxia-inducible factor-1α, vascular endothelial growth factor, and erythropoietin were higher in term than preterm pups, reflecting the hypoxic intrauterine environment of just-born term pups. Proneural genes, including Pax6 and Neurogenin-1 and -2, were higher in preterm rabbit pups compared with term pups. Importantly, neurogenesis and associated factors were restored in preterm pups by treatment with dimethyloxallyl glycine, a hypoxia mimetic agent. Hence, glutamatergic neurogenesis continues in the premature infants, preterm birth suppresses neurogenesis, and hypoxia-mimetic agents might restore neurogenesis, enhance cortical growth, and improve neurodevelopmental outcome of premature infants.
Parallel Processing of Environmental Recognition and Locomotion in the Mouse Striatum
Authors: Yamin Hagar G. , Stern Edward A. , Cohen Dana
Published: January 2013

Information processing in behaving animals has been the target of many studies in the striatum; however, its dynamics and complexity remain to a large extent unknown. Here, we chronically recorded neuronal populations in dorsal striatum as mice were exposed to a novel environment, a paradigm which enables the dissociation of locomotion and environmental recognition. The findings indicate that non-overlapping populations of striatal projection neurons—the medium spiny neurons—reliably encode locomotion and environmental identity, whereas two subpopulations of short-spike interneurons encode distinct information: the fast spiking interneurons preferentially encode locomotion whereas the second type of interneurons preferentially encodes environmental identity. The three neuronal subgroups used cell-type specific coding schemes. This study provides evidence for the existence of parallel processing circuits within the sensorimotor region of the striatum.
Relationship between lactation duration and insulin and glucose response among women with prior gestational diabetes
Authors: Chouinard-Castonguay Sarah , Weisnagel S John , Tchernof André , Robitaille Julie
Published: January 2013

Background

Few studies have investigated whether favorable effects of lactation persist after weaning and protect women with prior gestational diabetes mellitus (GDM) against later development of insulin resistance and insulin secretion defects.

Objective

To investigate the impact of lactation duration on insulin and glucose response among women with prior GDM.

Design/methods

The study group comprised 144 women with a history of GDM between 2003 and 2010. Plasma insulin and glucose concentrations were obtained from a 75 g oral glucose tolerance test (OGTT). Total lactation duration (exclusive breastfeeding and breast and bottle-feeding) for all infants was self-reported in months.

Results

Mean age was 36.5±5.0 years. Time between delivery and metabolic testing was 4.0±1.9 years. Women breastfed for an average of 13.9±16.8 months. Most women (80.6%) reported a history of lactation. Women who lactated had higher homeostasis model assessment for insulin sensitivity (HOMA-IS) and Matsuda indices and lower fasting and 2-h post-OGTT insulin concentrations as well as area under the curve (AUC) for insulin (P≤0.01 for all). Compared with women who lactated for <10 months, women who lactated for ≥10 months had improved insulin sensitivity–secretion index, higher HOMA-IS and Matsuda indices, lower fasting and 2-h post-OGTT insulin concentrations as well as AUC for insulin, and lower incidence of impaired glucose intolerance (P≤0.05 for all). In multiple linear regression analyses, lactation duration emerged as an independent predictor of fasting insulin concentrations (β=−0.02) and insulin sensitivity indices (β=0.02) (P≤0.05 for all).

Conclusions

These results suggest that longer duration of lactation is associated with improved insulin and glucose response among women with prior GDM.
Mapping Quantitative Trait Loci AffectingArabidopsis thalianaSeed Morphology Features Extracted Computationally From Images
Authors: Moore Candace R , Gronwall David S , Miller Nathan D , Spalding Edgar P
Published: January 2013

Seeds are studied to understand dispersal and establishment of the next generation, as units of agricultural yield, and for other important reasons. Thus, elucidating the genetic architecture of seed size and shape traits will benefit basic and applied plant biology research. This study sought quantitative trait loci (QTL) controlling the size and shape of Arabidopsis thaliana seeds by computational analysis of seed phenotypes in recombinant inbred lines derived from the small-seeded Landsberg erecta × large-seeded Cape Verde Islands accessions. On the order of 103 seeds from each recombinant inbred line were automatically measured with flatbed photo scanners and custom image analysis software. The eight significant QTL affecting seed area explained 63% of the variation, and overlapped with five of the six major-axis (length) QTL and three of the five minor-axis (width) QTL, which accounted for 57% and 38% of the variation in those traits, respectively. Because the Arabidopsis seed is exalbuminous, lacking an endosperm at maturity, the results are relatable to embryo length and width. The Cvi allele generally had a positive effect of 2.6–4.0%. Analysis of variance showed heritability of the three traits ranged between 60% and 73%. Repeating the experiment with 2.2 million seeds from a separate harvest of the RIL population and approximately 0.5 million seeds from 92 near-isogenic lines confirmed the aforementioned results. Structured for download are files containing phenotype measurements, all sets of seed images, and the seed trait measuring tool.
Comparison of the Performance of Two Commercial Genome-Wide Association Study Genotyping Platforms in Han Chinese Samples
Authors: Jiang Lei , Willner Dana , Danoy Patrick , Xu Huji , Brown Matthew A
Published: January 2013

Most genome-wide association studies to date have been performed in populations of European descent, but there is increasing interest in expanding these studies to other populations. The performance of genotyping chips in Asian populations is not well established. Therefore, we sought to test the performance of widely used fixed-marker, genome-wide association studies chips in the Han Chinese population. Non-HapMap Chinese samples (n = 396) were genotyped using the Illumina OmniExpress and Affymetrix 6.0 platforms, whereas a subset also were genotyped using the Immunochip. Genotyped markers from the Affymetrix 6.0 and Illumina OmniExpress were used for full genome imputation based on the HapMap 2 JPT+CHB (Japanese from Tokyo, Japan and Chinese from Beijing, China) reference panel. The concordance between markers genotypes for the three platforms was very high whether directly genotyped or genotyped and imputed single nucleotide polymorphisms (SNPs; >99.8% for directly genotyped and >99.5% for genotyped and imputed SNPs, respectively) were compared. The OmniExpress chip data enabled more SNPs to be imputed, particularly SNPs with minor allele frequency >5%. The OmniExpress chip achieved better coverage of HapMap SNPs than the Affymetrix 6.0 chip (73.6% vs. 65.9%, respectively, for minor allele frequency >5%). The Affymetrix 6.0 and Illumina OmniExpress chip have similar genotyping accuracy and provide similar accuracy of imputed SNPs. The OmniExpress chip however provides better coverage of Asian HapMap SNPs, although its coverage of HapMap SNPs is moderate.
Compensatory Mutations in Predicted Metal Transporters Modulate Auxin Conjugate Responsiveness in Arabidopsis
Authors: Rampey Rebekah A , Baldridge Megan T , Farrow David C , Bay Sarah N , Bartel Bonnie
Published: January 2013

Levels of the phytohormone indole-3-acetic acid (IAA) can be altered by the formation and hydrolysis of IAA conjugates. The isolation and characterization of Arabidopsis thaliana mutants with reduced IAA-conjugate sensitivity and wild-type IAA responses is advancing the understanding of auxin homeostasis by uncovering the factors needed for conjugate metabolism. For example, the discovery that the IAA-Ala-resistant mutant iar1 is defective in a protein in the ZIP family of metal transporters uncovered a link between metal homeostasis and IAA-conjugate sensitivity. To uncover additional factors impacting auxin conjugate metabolism, we conducted a genetic modifier screen and isolated extragenic mutations that restored IAA-amino acid conjugate sensitivity to the iar1 mutant. One of these suppressor mutants is defective in a putative cation diffusion facilitator, MTP5 (At3g12100; formerly known as MTPc2). Loss of MTP5 function restored IAA conjugate sensitivity to iar1 but not to mutants defective in IAA-amino acid conjugate amidohydrolases. Our results are consistent with a model in which MTP5 and IAR1 transport metals in an antagonistic fashion to regulate metal homeostasis within the subcellular compartment in which the IAA-conjugate amidohydrolases reside, and support previous suggestions that the ion composition in this compartment influences hydrolase activity.
Optimized Hot-forming of an Intermetallic Multi-phase γ-TiAl Based Alloy
Authors: Gaitzenauer Andrea , Müller Martin , Clemens Helmut , Voigt Patrick , Hempel Robert , Mayer Svea
Published: January 2013

A robust processing route at low cost is an essential requirement for high-temperature materials used in automotive engines. Because of their excellent high-temperature properties, their low density, high elastic modulus as well as high specific strength, intermetallic γ-TiAl based alloys are potential candidates for application in advanced automotive turbochargers. So-called 3rdgeneration alloys, such as TNM™ alloys with a nominal composition of Ti-43.5Al-4Nb-1Mo-0.1B (in at%), are multi-phase alloys consisting of γ-TiAl, α2-Ti3Al and a low volume fraction of βo-TiAl phase. In this paper a novel hot-processing route, which is a combination of a one-shot hot-forging step and a controlled cooling treatment, leads to mechanical properties required for turbocharger turbine wheels. The observed strength can be attributed to the small lamellar spacing within the α2/γ colonies of the nearly lamellar microstructure. In order to analyze the microstructure and the prevailing phase fractions microscopic examinations and X-ray diffraction measurements were conducted. The mechanical properties were determined by hardness measurements as well as tensile and creep tests. The evolution of the microstructure during the hot-forming process is described and its relation to the obtained mechanical properties.
High Temperature Oxidation Protection of Multi-Phase Mo-Containing TiAl-Alloys by the Fluorine Effect
Authors: Donchev Alexander , Pflumm Raluca , Mayer Svea , Clemens Helmut , Schütze Michael
Published: January 2013

Intermetallic titanium aluminides are potential materials for application in high temperature components. In particular, alloys solidifying via the β-phase are of great interest because they possess a significant volume fraction of the disordered body-centered cubic β-phase at elevated temperatures ensuring good processing characteristics during hot-working. Nevertheless, their practical use at temperatures as high as 800°C requires improvements of the oxidation resistance. This paper reports on the fluorine effect on a multi-phase TiAl-alloy in the cast and hot-isostatically pressed condition at 800°C in air. The behavior of the so-called TNM material (Ti-43.5Al-4Nb-1Mo-0.1B, in at %) was compared with that of two other TiAl-alloys which are Nb-free and contain different amounts of Mo (3 and 7 at%, respectively). The oxidation resistance of the fluorine treated samples was significantly improved compared to the untreated samples. After fluorine treatment all alloys exhibit slow alumina kinetics indicating a positive fluorine effect. Results of isothermal and thermocyclic oxidation tests at 800°C in air are presented and discussed in the view of composition and microstructure of the TiAl-alloys investigated, along with the impact of the fluorine effect on the oxidation resistance of these materials.
Collocation and Integration of Back-End Fuel Cycle Facilities with the Repository: Implications for Waste Forms
Authors: Forsberg Charles
Published: January 2013

The organization of the fuel cycle is a legacy of World War II and the cold war. Fuel cycle facilities were developed and deployed without consideration of the waste management implications. This led to the fuel cycle model of an isolated single-purpose geological repository for disposal of wastes shipped from distant processing facilities. There is an alternative: collocation and integration of reprocessing and other backend facilities with the repository. Such an option alters waste form functional requirements by reducing storage and transport requirements. This, in turn, broadens the choice of waste forms by relaxing the incentives to minimize waste volumes. Waste forms can be chosen primarily on meeting two goals: repository performance and minimizing costs. Less restrictive waste volume constraints enable termination of safeguards on all wastes, enable use of solubility-limited waste forms, and reduce radiation damage as a waste form limitation. The implications of such changes in waste form requirements are discussed.
Impact of Annealing on the Thermoelectric Properties of Ge2Sb2Te5Films
Authors: Lee Jaeho , Kodama Takashi , Won Yoonjin , Asheghi Mehdi , Goodson Kenneth E.
Published: January 2013

Thermoelectric phenomena strongly influence the behavior of chalcogenide materials in nanoelectronic devices including phase-change memory cells. This paper presents the annealing temperature and phase dependent thermoelectric properties of Ge2Sb2Te5films including the thermoelectric power factor and the figure of merit. The Ge2Sb2Te5films annealed at different temperatures contain varying fractions of the amorphous and crystalline phases which strongly influence the thermoelectric properties. The thermoelectric power factor increases fom 3.2 μW/mK2to 65 μW/mK2as the crystal phase changes from face-centered cubic to hexagonal close-packed. The data are consistent with modeling based on effective medium theory and suggest that careful consideration of phase purity is needed to improve the figures of merit for phase change memories and potentially for thermoelectric energy conversion applications.
Relaxation Processes at High Temperature in TiAl-Nb-Mo Intermetallics
Authors: Simas Pablo , Schmoelzer Thomas , Mayer Svea , Nó Maria L. , Clemens Helmut , San Juan Jose
Published: January 2013

In the last decades there was a growing interest in developing new light-weight intermetallic alloys, which are able to substitute the heavy superalloys at a certain temperature range. At present a new Ti-Al-Nb-Mo family, called TNM™ alloys, is being optimized to fulfill the challenging requirements. The aim of the present work was to study the microscopic mechanisms of defect mobility at high temperature in TNM alloys in order to contribute to the understanding of their influence on the mechanical properties and hence to promote the further optimization of these alloys. Mechanical spectroscopy has been used to study the internal friction and the dynamic modulus up to 1460 K of a TNM alloy under different thermal treatments. These measurements allow to follow the microstructural evolution during in-situ thermal treatments. A relaxation process has been observed at about 1050 K and was characterized as a function of temperature and frequency in order to obtain the activation parameters of the responsible mechanism. In particular, the activation enthalpy has been determined to be H= 3 eV. The results are discussed and an atomic mechanism is proposed to explain the observed relaxation process.
Crystal Polarity and Electrical Properties of Heavily Doped ZnO Films
Authors: Adachi Yutaka , Ohashi Naoki , Sakaguchi Isao , Haneda Hajime
Published: January 2013

In this study, ZnO f ilms heavily doped with Al or Ga were grown on a polarity-controlled buffer layer using pulsed laser deposition. The films prepared using a 1 mol% Al-doped target with the buffer layer grown at 700 °C had the c(+)-face, whereas the films with the buffer layer grown at 400 °C had the c(-)-face, which means that the polarity control can be successfully carried out using the buffer layer. However, the films prepared using targets doped with more than 1 mol% Al or Ga had the c(+)-face regardless of the polarity of the buffer layer. The 1 mol% Al-doped ZnO film with the c(+)-face had lower electron concentration and higher growth rate than the film with the c(-)-face. This result indicates that the Al content in the film with the c(-)-face was larger than that in the film with the c(+)-face.
Optical, Structural, and Electrical Properties of Vanadium Dioxide Grown on Sapphire Substrates with Different Crystallographic Orientations
Authors: Nazari M. , Zhao Y. , Zhu Y. , Kuryatkov V. V. , Bernussi A. A. , Fan Z. , Holtz M.
Published: January 2013

The phase transition of VO2 grown on sapphire having different crystallographic growth planes is examined experimentally. Measurements of electrical resistivity are compared with spectroscopic ellipsometry studies, to obtain complex index of refraction and plasma frequency, and transmission in the terahertz frequency range, each as a function of temperature.
Development of Plasma-Assisted Processing for Selenization and Sulfurization of Absorber Layers
Authors: Kosaraju S. , Repins I. , Wolden C. A.
Published: January 2013

In the synthesis of copper chalcopyrite solar absorbers the chalcogen source is always supplied in excess due to its low reactivity. This paper describes preliminary work aimed at addressing this issue through plasma processing. An inductively coupled plasma (ICP) was use to activate both sulfur and selenium vapors. First, the thermodynamic arguments for using activated chalcogens are presented. Next, this paper describes the experimental ICP setup and its characterization using optical emission spectroscopy (OES). Stable discharges have been achieved with both sulfur and selenium vapors using argon as a carrier gas. The potential of this approach was demonstrated by converting indium films into In2Se3 and InSx. The indium samples were inserted into chalcogen-containing ICP plasmas. Through X-ray diffraction it was observed that chalcogen conversion was achieved in a matter of minutes at room temperature by plasma processing.
Effect of thermal cycling on performance of Poly(3-hexylthiophene) Transistors
Authors: Mattis Brian A. , Chang Paul C. , Subramanian Vivek
Published: January 2013

We present the results of studies on the electrical and physical modifications to Poly(3-hexylthiophene), upon thermal annealing. Thermally-induced performance modifications and thermal stability of polythiophene thin film transistors are explored. We observe substantial mobility improvements in devices annealed at low temperatures (>80°C), as well as increases in on/off ratios by two orders of magnitude at moderate anneal temperatures (~120°C). We document changes in conductivity, mobility, on current, and on/off ratio with anneal temperature and total thermal budget. In conjunction with material analysis, we develop qualitative models for the mechanisms involved in the annealing/degradation processes. Hence, this study provides a comprehensive analysis of the effect of thermal cycling of polythiophene TFTs on various device performance metrics, and identifies the relevant thermal limits and failure mechanisms.
Exposure of mortars to cyclic chloride ingress and carbonation
Authors: Backus Jonathon , McPolin Danny , Basheer Muhammed , Long Adrian , Holmes Niall
Published: January 2013

The presence of chloride ions is one of the primary factors causing the degradation of reinforced concrete structures. An investigation to monitor ingress of chlorides during a 24-week wetting and drying exposure regime to simulate conditions in which multiple-mode transport mechanisms are active was conducted on a variety of binders. Penetration was evaluated using free and total chloride profiles. Acid extraction of chlorides is quantitatively reliable and practical for assessing penetration. X-ray diffraction was used to determine the presence of bound chlorides and carbonation. The ability of the cement blends to resist chloride penetration was, from best to worst, ground granulated blast-furnace slag, microsilica, pulverised-fuel ash, Portland cement. The effect of carbonation on binding capability was observed and the relative quantity of chlorides also showed a correlation with the amount of chlorides bound in the form of Friedel's salt.
The effect of prehydration on the engineering properties of CEM I Portland cement
Authors: Whittaker Mark , Dubina Elina , Al-Mutawa Faisal , Arkless Leslie , Plank Johann , Black Leon
Published: January 2013

Prehydration – the reaction between anhydrous cement and water vapour – has deleterious effects on engineering properties such as compressive strength, workability and setting time. This study assessed changes in the engineering properties of CEM I Portland cement exposed to relative humidities (RHs) of 60% or 85% for 7 and 28 days. Thin layers (no more than 2 mm thick) of CEM I 42.5R cement were exposed to controlled RHs of 60% and 85%, followed by assessment of compressive strength, setting time and workability. These measurements were complemented by characterising the prehydrated anhydrous cement using isothermal calorimetry, scanning electron microscopy, X-ray diffraction and thermal gravimetric analysis. Following prehydration at 60% RH, conventional hydration resulted in a negligible reduction in strength development plus a decrease in workability and increase in setting time. At 85% RH, compressive strength was greatly reduced, particularly at early ages. There was also a greater loss of workability and increase in setting time.
On a new hydraulic binder from stainless steel converter slag
Authors: Pontikes Yiannis , Kriskova Lubica , Cizer Özlem , Jones Peter Tom , Blanpain Bart
Published: January 2013

The aim of this work was to investigate the hydraulic behaviour of a stainless steel converter slag after changing its chemical composition and cooling path. The target slag was designed to resemble ground granulated blast-furnace slag (GGBFS). A synthetic slag with a chemical composition close to stainless steel converter slags was mixed with 22, 30 and 38 wt% fly ash (FA) from lignite combustion, heated up to 1550°C and then granulated by quenching in water; the solidified new slags were named FA22, FA30 and FA38 respectively. Quantitative X-ray diffraction on FA22 revealed that the amorphous phase was approximately 40 wt%, the rest being bredigite and merwinite. For FA addition of 30 wt% or more, the amorphous phase reached almost 100 wt%. The resulting slags showed significant hydraulic activity when mixed with sodium-based activators, with C-S-H, hydrotalcite and hydrogarnet being the main hydration products formed. The calorimetric behaviour and the mechanical properties of blended cements with 30 wt% FA30 and FA38 were comparable to a blended cement with GGBFS. Assuming that FA addition will take place during the liquid state of the slag, the proposed process can result in a new hydraulic binder.
Aspects of replacing gypsum with other calcium salts in Portland cement
Authors: Justnes Harald
Published: January 2013

Calcium sulfate (e.g. gypsum) is the common set regulator in Portland cement. It has been shown that ground clinker can be set regulated by calcium salts other than gypsum, in particular calcium acetate, formate and nitrate. Rheology of the paste is improved when gypsum is replaced by other salts, probably due to less water binding and surface hydration products without the needle-like morphology of ettringite. In particular, for calcium nitrate, the cumulative hydration temperature is reduced, which allows for low-energy cement without changing clinker chemistry. Removing calcium sulfate all together may also allow heat curing or evolution of hydration heat in massive structures to exceed 70°C without risking delayed ettringite formation. These aspects have been elucidated by the experiments reported in this paper.