bluuebunny/crossref_metadata_2025 huggingface dataset:
Organization and modulation of nuclear lamina structure
Authors: Gerace Larry , Comeau Claudette , Benson Mary
Published: April 2013

The nuclear lamina is a protein meshwork associated with the nucleoplasmic surface of the inner nuclear membrane, that is suggested to be important for organizing nuclear envelope and interphase chromosome architecture. To investigate the structural organization of the lamina, we have analysed rat liver nuclear envelopes by various chemical extraction procedures. From these studies, we have defined conditions that yield a nuclear envelope subfraction that is both highly enriched in the lamina and devoid of pore complexes. This fraction contains mostly lamins A, B and C, the three major lamina polypeptides that are apparently arranged in a polymeric assembly. Our chemical extraction studies also indicate that lamin B has a stronger interaction with nuclear membranes than the other two lamins, and support the possibility that lamin B is important for attaching the lamina to the inner nuclear membrane.

We have examined the synthesis and assembly of the lamins during interphase in tissue-culture cells to investigate lamina structure by a second approach. We found that all three lamins are synthesized at similar rates throughout the cell cycle in synchronized Chinese hamster ovary cells, and that their biosynthesis is not temporally coupled to DNA replication. Our studies indicate that newly synthesized lamins are rapidly assembled into an insoluble lamina structure but that the apparent half-time for lamina insertion differs for individual lamins. We have also observed that lamin A is synthesized as an apparent precursor molecule that is converted to mature lamin A only after integration into the lamina structure.

The lamina is reversibly depolymerized during cell division, a process that may be mediated by enzymic phosphorylation of the lamins. To investigate this possibility further, we have analysed charge-altering modifications of the lamins on two-dimensional gels, and have found that phosphorylation is the only detectable modification of these proteins that occurs specifically during mitosis. Furthermore, we have determined that when the lamins are disassembled during metaphase, each lamin has approximately 2 moles of associated phosphate/mole lamin, a value that is four to sevenfold higher than the average interphase level. Considering this information, we discuss a model by which depolymerization and reassembly of the lamina can regulate the reversible disassembly of the nuclear envelope during mitosis.
School of Professor S.V. Belov (to the anniversary of Life Activity Safety founder)
Authors: Павлихин  , Pavlikhin Gennadiy , Жердев  , Zherdev A. , Коршунов  , Korshunov S. , Федоров  , Fedorov I. , Александров  , Aleksandrov Anatoliy , Девисилов  , Devisilov Vladimir , Суровцев  , Surovtsev I.
Published: April 2013

Stages of activity of Sergey Viktorovich Belov, Professor of Moscow State Technical University named after N.E. Bauman, on creation of new scientific and educational direction “Life Activity Safety” are briefly considered. Now it is possible to speak about S.V. Belov’s school which bases were put nearly 30 years ago. The new educational direction created in Russia has a world priority and actively evolves all over the levels of Russian education system.
Institutionalization and the Genesis of Noxological Education
Authors: Девисилов  , Devisilov Vladimir , Ванаев  , Vanaev V.
Published: April 2013

Questions of noxological education institutionalization and genesis from science and practice origin in the field of safety through three chronological stages up to introduction of new subject domain «noxology» are considered in this article. Genealogy of noxological education is presented, allowing to track transformation of scientific and educational area and foreseen its development tendency.
Population Information Support in Case of Threat or Occurrence of Emergency Situations on Transport
Authors: Веденеева  , Vedeneeva T. , Омельченко  , Omelchenko M. , Лукьянович  , Lukyanovich Aleksey , Попова  , Popova A.
Published: April 2013

Questions of population informing and alerting on transport infrastructure objects’ territories in case of threat or occurrence of emergency situations or terroristic acts are considered in this article. Results of trial operation of protection system segments against the emergency situations of natural and technogenic character, as well as results of informing and alerting of population in transport and results of public opinion researches on the questions of satisfaction with system are presented. Directions of further development and improvement of the system are defined on the basis of revealed shortcomings.
A Social Information Processing Perspective of Coworker Influence on a Focal Employee
Authors: Chen Zhijun , Takeuchi Riki , Shum Cass
Published: April 2013

Acritical omission in the coworker influence literature is how a coworker influences a closely related (focal) employee’s job performance behaviors and whether this influence is contingent on that coworker’s own behaviors. By integrating social information processing and social cognitive theories with social exchange and role theories, we hypothesize that there are, at least, three distinct types of coworker dyadic influence. Accordingly, we developed and tested a moderated mediation model to explicate such influence. Two multisource, field-design studies conducted in Hong Kong support the modeled relationships in that employee role ambiguity partially mediated the relationships between coworker–employee exchange and two types of employee job performance behaviors—task performance and organizational citizenship behavior (OCB). Furthermore, coworker OCB fostered employee job performance behavior both directly and interactively, acting as a moderator to weaken the relationships between employee role ambiguity and the two types of job performance behaviors.
Efficacy and Safety Evaluation of a Large Niacin Therapeutic Interchange Program
Authors: Chaffman Michael O , Webster William B , Winiecki John T
Published: April 2013

BACKGROUND

An extended-release niacin product (Niaspan, Abbott Laboratories) was identified as a product with a less costly therapeutic alternative; a therapeutic product interchange was implemented.

OBJECTIVE

To evaluate the efficacy and safety of a product therapeutic interchange from Niaspan to a controlled-release niacin product (Slo-Niacin, Upsher-Smith Laboratories) among patients at a large US Department of Veterans Affairs health care facility.

METHODS

Patients with active prescriptions for Niaspan underwent a therapeutic product interchange to Slo-Niacin; following conversion of the product, the medical record for each patient was reviewed and pre- and postconversion clinical information and conversion details were transcribed into a database for subsequent analysis and study. The primary efficacy end point was pre- and postconversion level of low-density lipoprotein cholesterol; secondary efficacy end points were levels of serum total cholesterol, high-density lipoprotein cholesterol, and triglycerides. Abnormal serum liver enzyme levels greater than 3 times the upper limits of normal was the primary safety end point; blood hemoglobin A1c was assessed as a secondary safety end point.

RESULTS

A total of 5321 patients' medical records were reviewed; for the efficacy evaluation, 539 patients were maintained on a daily dose of Slo-Niacin that was the same as the previous Niaspan dose. The dosage of any other concurrently prescribed dyslipidemia medication was unchanged. Analysis of these cases indicated that the conversion of Niaspan to Slo-Niacin was not associated with a difference in serum lipids over a mean (SD) of 503.9 (98.0) postconversion observation days with the exception of a decrease in mean serum triglyceride concentration of 19.8 mg/dL (p = 0.0003). Evaluation of all 5321 patients given Slo-Niacin for up to 724 days did not detect any safety differences between Slo-Niacin and Niaspan. Local facility cost avoidance exceeded $800,000 in the first postconversion year.

CONCLUSIONS

Data from a medication use evaluation of modified-release niacin products therapeutic interchange in a large US Department of Veterans Affairs health care facility show that the switch from Niaspan to Slo-Niacin had no negative effects on lipid-altering efficacy or safety but generated significant cost avoidance.
Skeletal Muscle Calpain Acts through Nitric Oxide and Neural miRNAs to Regulate Acetylcholine Release in Motor Nerve Terminals
Authors: Zhu Haipeng , Bhattacharyya Bula J. , Lin Hong , Gomez Christopher M.
Published: April 2013

Cholinergic overactivity in diseases of neuromuscular transmission elicits a retrograde signal resembling homeostatic synaptic plasticity that downregulates transmitter release. Understanding this compensatory pathway could provide insights into novel therapeutic avenues and molecular mechanisms underlying learning and memory. Here we identify nitric oxide as a possible source of this signal in pathological human and mouse muscle samples and link this signaling pathway to changes in synaptic function in the neuromuscular junction. We further show that neuronal nitric oxide synthase is regulated by cholinergic excess through activation of skeletal muscle calpain and its effect on Cdk5 and CaMKII, leading to direct modulation of presynaptic function. Finally, we show that this signaling pathway acts through specific miRNA control of presynaptic vesicle protein expression. The control of presynaptic miRNA levels by postsynaptic activity represents a novel mechanism for the modulation of synaptic activity in normal or pathological conditions.
Genome-Wide Expression Analysis ofPtf1a- andAscl1-Deficient Mice Reveals New Markers for Distinct Dorsal Horn Interneuron Populations Contributing to Nociceptive Reflex Plasticity
Authors: Wildner Hendrik , Das Gupta Rebecca , Bröhl Dominique , Heppenstall Paul A. , Zeilhofer Hanns Ulrich , Birchmeier Carmen
Published: April 2013

Inhibitory interneurons of the spinal dorsal horn play critical roles in the processing of noxious and innocuous sensory information. They form a family of morphologically and functionally diverse neurons that likely fall into distinct subtypes. Traditional classifications rely mainly on differences in dendritic tree morphology and firing patterns. Although useful, these markers are not comprehensive and cannot be used to drive specific genetic manipulations targeted at defined subsets of neurons. Here, we have used genome-wide expression profiling of spinal dorsal horns of wild-type mice and of two strains of transcription factor-deficient mice (Ptf1a−/−andAscl1/Mash1−/−mice) to identify new genetic markers for specific subsets of dorsal horn inhibitory interneurons.Ptf1a−/−mice lack all inhibitory interneurons in the dorsal horn, whereas only the late-born inhibitory interneurons are missing inAscl1−/−mice. We found 30 genes that were significantly downregulated in the dorsal horn ofPtf1a−/−mice. Twenty-one of those also showed reduced expression inAscl1−/−mice.In situhybridization analyses of all 30 genes identified four genes with primarily non-overlapping expression patterns in the dorsal horn. Three genes,pDyncoding the neuropeptide dynorphin,Kcnip2encoding a potassium channel associated protein, and the nuclear receptor encoding geneRorb, were expressed inAscl1-dependent subpopulations of the superficial dorsal horn. The fourth gene,Tfap2b, encoding a transcription factor, is expressed mainly in aAscl1-independent subpopulation of the deep dorsal horn. Functional experiments in isolated spinal cords showed that theAscl1-dependent inhibitory interneurons are key players of nociceptive reflex plasticity.
Intra-axonal Synthesis of Eukaryotic Translation Initiation Factors Regulates Local Protein Synthesis and Axon Growth in Rat Sympathetic Neurons
Authors: Kar Amar N. , MacGibeny Margaret A. , Gervasi Noreen M. , Gioio Anthony E. , Kaplan Barry B.
Published: April 2013

Axonal protein synthesis is a complex process involving selective mRNA localization and translational regulation. In this study, usingin situhybridization and metabolic labeling, we show that the mRNAs encoding eukaryotic translation initiation factors eIF2B2 and eIF4G2 are present in the axons of rat sympathetic neurons and are locally translated. We also report that a noncoding microRNA, miR16, modulates the axonal expression of eIF2B2 and eIF4G2. Transfection of axons with precursor miR16 and anti-miR16 showed that local miR16 levels modulated axonal eIF2B2 and eIF4G2 mRNA and protein levels, as well as axon outgrowth. siRNA-mediated knock-down of axonal eIF2B2 and eIF4G2 mRNA also resulted in a significant decrease in axonal eIF2B2 and eIF4G2 protein. Moreover, results of metabolic labeling studies showed that downregulation of axonal eIF2B2 and eIF4G2 expression also inhibited local protein synthesis and axon growth. Together, these data provide evidence that miR16 mediates axonal growth, at least in part, by regulating the local protein synthesis of eukaryotic translation initiation factors eIF2B2 and eIF4G2 in the axon.
Increasing Tip60 HAT Levels Rescues Axonal Transport Defects and Associated Behavioral Phenotypes in aDrosophilaAlzheimer's Disease Model
Authors: Johnson Ashley A. , Sarthi Jessica , Pirooznia Sheila K. , Reube William , Elefant Felice
Published: April 2013

Axonal transport defects and axonopathy are prominent in early preclinical stages of Alzheimer's disease (AD), often preceding known disease-related pathology by over a year. As epigenetic transcriptional regulatory mechanisms, such as histone acetylation, are critical for neurogenesis, it is postulated that their misregulation might be linked to early pathophysiological mechanisms that contribute to AD. The histone acetyltransferase (HAT) Tip60 epigenetically regulates genes enriched for neuronal functions and is implicated in AD via its formation of a transcriptional regulatory complex with the amyloid precursor protein (APP) intracellular domain. Disruption of APP function is associated with axonal transport defects, raising the possibility that an epigenetic role for Tip60 might also be involved. Here, we examine whether Tip60 HAT activity functions in axonal transport usingDrosophilaCNS motor neurons as a well-characterized transport model. We show that reduction of Tip60 HAT activity in the nervous system causes axonopathy and transport defects associated with epigenetic misregulation of certain axonal transport-linked Tip60 target genes. Functional consequences of these defects are evidenced by reduced locomotion activity of the mutant Tip60 larvae, and these phenotypes can be partially rescued with certain histone deacetylase inhibitors. Finally, we demonstrate that Tip60 function in axonal transport is mediated by APP and that, remarkably, excess Tip60 exerts a neuroprotective role in APP-induced axonal transport and functional locomotion defects. Our observations highlight a novel functional interactive role between Tip60 HAT activity and APP in axonal transport and provide insight into the importance of specific HAT modulators for cognitive disorder treatment.
Ligand-Gating by Ca2+Is Rate Limiting for Physiological Operation of BKCaChannels
Authors: Berkefeld Henrike , Fakler Bernd
Published: April 2013

Large conductance Ca2+- and voltage-activated potassium channels (BKCa) shape neuronal excitability and signal transduction. This reflects the integrated influences of transmembrane voltage and intracellular calcium concentration ([Ca2+]i) that gate the channels. This dual gating has been mainly studied as voltage-triggered gating modulated by defined steady-state [Ca2+]i, a paradigm that does not approximate native conditions. Here we use submillisecond changes of [Ca2+]ito investigate the time course of the Ca2+-triggered gating of BKCachannels expressed in Chinese hamster ovary cells at distinct membrane potentials in the physiological range. The results show that Ca2+can effectively gate BKCachannels and that Ca2+gating is largely different from voltage-driven gating. Most prominently, Ca2+gating displays a pronounced delay in the millisecond range between Ca2+application and channel opening (pre-onset delay) and exhibits slower kinetics across the entire [Ca2+]i-voltage plane. Both characteristics are selectively altered by co-assembled BKβ4 or an epilepsy-causing mutation that either slows deactivation or speeds activation and reduces the pre-onset delay, respectively. Similarly, co-assembly of the BKCachannels with voltage-activated Ca2+(Cav) channels, mirroring the native configuration, decreased the pre-onset delay to submillisecond values. In BKCa–Cav complexes, the time course of the hyperpolarizing K+-current response is dictated by the Ca2+gating of the BKCachannels. Consistent with Cav-mediated Ca2+influx, gating was fastest at hyperpolarized potentials, but decreased with depolarization of the membrane potential. Our results demonstrate that under experimental paradigms meant to approximate the physiological conditions BKCachannels primarily operate as ligand-activated channels gated by intracellular Ca2+and that Ca2+gating is tuned for fast responses in neuronal BKCa–Cav complexes.
Enhanced Tonic Inhibition Influences the Hypnotic and Amnestic Actions of the Intravenous Anesthetics Etomidate and Propofol
Authors: Kretschmannova Karla , Hines Rochelle M. , Revilla-Sanchez Raquel , Terunuma Miho , Tretter Verena , Jurd Rachel , Kelz Max B. , Moss Stephen J. , Davies Paul A.
Published: April 2013

Intravenous anesthetics exert a component of their actions via potentiating inhibitory neurotransmission mediated by γ-aminobutyric type-A receptors (GABAARs). Phasic and tonic inhibition is mediated by distinct populations of GABAARs, with the majority of phasic inhibition by subtypes composed of α1–3βγ2 subunits, whereas tonic inhibition is dependent on subtypes assembled from α4–6βδ subunits. To explore the contribution that these distinct forms of inhibition play in mediating intravenous anesthesia, we have used mice in which tyrosine residues 365/7 within the γ2 subunit are mutated to phenyalanines (Y365/7F). Here we demonstrate that this mutation leads to increased accumulation of the α4 subunit containing GABAARs in the thalamus and dentate gyrus of female Y365/7F but not male Y365/7F mice. Y365/7F mice exhibited a gender-specific enhancement of tonic inhibition in the dentate gyrus that was more sensitive to modulation by the anesthetic etomidate, together with a deficit in long-term potentiation. Consistent with this, female Y365/7F, but not male Y365/7F, mice exhibited a dramatic increase in the duration of etomidate- and propofol-mediated hypnosis. Moreover, the amnestic actions of etomidate were selectively potentiated in female Y365/7F mice. Collectively, these observations suggest that potentiation of tonic inhibition mediated by α4 subunit containing GABAARs contributes to the hypnotic and amnestic actions of the intravenous anesthetics, etomidate and propofol.
Cancelling Prism Adaptation by a Shift of Background: A Novel Utility of Allocentric Coordinates for Extracting Motor Errors
Authors: Uchimura Motoaki , Kitazawa Shigeru
Published: April 2013

Many previous studies have reported that our brains are able to encode a target position not only in body-centered coordinates but also in terms of landmarks in the background. The importance of such allocentric memory increases when we are forced to complete a delayed reaching task after the target has disappeared. However, the merit of allocentric memory in natural situations in which we are free to make an immediate reach toward a target has remained elusive. We hypothesized that allocentric memory is essential even in an immediate reach for dissociating between error attributable to the motor system and error attributable to target motion. We show here in humans that prism adaptation, that is, adaptation of reaching movements in response to errors attributable to displacement of the visual field, can be cancelled or enhanced simply by moving the background in mid-flight of the reaching movement. The results provide direct evidence for the novel contribution of allocentric memory in providing information on “where I intended to go,” thereby discriminating the effect of target motion from the error resulting from the issued motor control signals.
Mitochondrial Exchanger NCLX Plays a Major Role in the Intracellular Ca2+Signaling, Gliotransmission, and Proliferation of Astrocytes
Authors: Parnis Julia , Montana Vedrana , Delgado-Martinez Ignacio , Matyash Vitali , Parpura Vladimir , Kettenmann Helmut , Sekler Israel , Nolte Christiane
Published: April 2013

Mitochondria not only provide cells with energy, but are central to Ca2+signaling. Powered by the mitochondrial membrane potential, Ca2+enters the mitochondria and is released into the cytosol through a mitochondrial Na+/Ca2+exchanger. We established that NCLX, a newly discovered mitochondrial Na+/Ca2+exchanger, is expressed in astrocytes isolated from mice of either sex. Immunoblot analysis of organellar fractions showed that the location of NCLX is confined to mitochondria. Using pericam-based mitochondrial Ca2+imaging and NCLX inhibition either by siRNA or by the pharmacological blocker CGP37157, we demonstrated that NCLX is responsible for mitochondrial Ca2+extrusion. Suppression of NCLX function altered cytosolic Ca2+dynamics in astrocytes and this was mediated by a strong effect of NCLX activity on Ca2+influx via store-operated entry. Furthermore, Ca2+influx through the store-operated Ca2+entry triggered strong, whereas ER Ca2+release triggered only modest mitochondrial Ca2+transients, indicating that the functional cross talk between the plasma membrane and mitochondrial domains is particularly strong in astrocytes. Finally, silencing of NCLX expression significantly reduced Ca2+-dependent processes in astrocytes (i.e., exocytotic glutamate release,in vitrowound closure, and proliferation), whereas Ca2+wave propagation was not affected. Therefore, NCLX, by meditating astrocytic mitochondrial Na+/Ca2+exchange, links between mitochondria and plasma membrane Ca2+signaling, thereby modulating cytoplasmic Ca2+transients required to control a diverse array of astrocyte functions.
Representation of Abstract Quantitative Rules Applied to Spatial and Numerical Magnitudes in Primate Prefrontal Cortex
Authors: Eiselt Anne-Kathrin , Nieder Andreas
Published: April 2013

Processing quantity information based on abstract principles is central to intelligent behavior. Neural correlates of quantitative rule selectivity have been identified previously in the prefrontal cortex (PFC). However, whether individual neurons represent rules applied to multiple magnitude types is unknown. We recorded from PFC neurons while monkeys switched between “greater than/less than” rules applied to spatial and numerical magnitudes. A majority of rule-selective neurons responded only to the quantitative rules applied to one specific magnitude type. However, another population of neurons generalized the magnitude principle and represented the quantitative rules related to both magnitudes. This indicates that the primate brain uses rule-selective neurons specialized in guiding decisions related to a specific magnitude type only, as well as generalizing neurons that respond abstractly to the overarching concept “magnitude rules.”
TSH induces metallothionein 1 in thyrocytes via Gq/11- and PKC-dependent signaling
Authors: Bäck Christer M , Stohr Stefanie , Schäfer Eva A M , Biebermann Heike , Boekhoff Ingrid , Breit Andreas , Gudermann Thomas , Büch Thomas R H
Published: April 2013

Metallothioneins (MTs) are cytoprotective proteins acting as scavengers of toxic metal ions or reactive oxygen species. MTs are upregulated in follicular thyroid carcinoma and are regarded as a marker of thyroid stress in Graves' disease. However, the mechanism of MT regulation in thyrocytes is still elusive. In other cellular systems, cAMP-, calcium-, or protein kinase C (PKC)-dependent signaling cascades have been shown to induce MT expression. Of note, all of these three pathways are activated following the stimulation of the TSH receptor (TSHR). Thus, we hypothesized that TSH represents a key regulator of MT expression in thyrocytes. In fact, TSHR stimulation induced expression of MT isoform 1X (MT1X) in human follicular carcinoma cells. In these cells, Induction of MT1X expression critically relied on intact Gq/11signaling of the TSHR and was blocked by chelation of intracellular calcium and inhibition of PKC. TSHR-independent stimulation of cAMP formation by treating cells with forskolin also led to an upregulation of MT1X, which was completely dependent on PKA. However, inhibition of PKA did not affect the regulation of MT1X by TSH. As in follicular thyroid carcinoma cells, TSH also induced MT1 protein in primary human thyrocytes, which was PKC dependent as well. In summary, these findings indicate that TSH stimulation induces MT1X expression via Gq/11and PKC, whereas cAMP–PKA signaling does not play a predominant role. To date, little has been known regarding cAMP-independent effects of TSHR signaling. Our findings extend the knowledge about the PKC-mediated functions of the TSHR.
Prediction of hot flow curves of construction steels by physically-based constitutive equations
Authors: Varela-Castro G. , Cabrera J.M.
Published: April 2013

The development of accurate constitutive equations is important for the success of computer simulations of high temperature forming operations. Often, these simulations must be made on alloys that have not been completely characterized. For that reason physically-based constitutive equations taking the chemical composition into consideration, involving deformation mechanisms and characteristic properties of the material are necessary. The influence that exerts the solute elements to an alloy on the mechanisms of diffusion on deformation processes at high temperatures is not an easy subject and the available information in literature is scarce.

This study examines that influence working on the basis of eight structural plain carbon steels with the chemical composition ranging between 0.15-0.45%C, 0.2-0.4%Si and 0.6-1.6%Mn produced by Electro-Slag Remelting ESR process and tested by isothermal uniaxial compression technique. The studied deformation conditions include strain rates ranging between 5·10−4 to 1·10−1 s−1 and temperatures between 0.6-0.75Tm, with Tm the melting temperature.

A constitutive expression for the hot working behavior is proposed, it includes the variation of the diffusion parameters with the chemical composition. To such aim the effect of the chemical composition of the alloy on the pre-exponential factor D0 of the gamma iron self-diffusion coefficient Dsd is included. Finally, a comparison of the experimental and predicted results shows the good agreement of the model with experimental flow data.
Enhanced Performance of Symmetric Double Layer Capacitor by Flexible Binder-free SWCNT Membrane Electrodes
Authors: Ma Danhao , Kalupson James , Shetty Pralav , Adu Kofi , Rajagopalan Ramakrishnan
Published: April 2013

We present results on an aqueous symmetric double layer electrochemical capacitor (EDLC) constructed with a flexible binder-free single wall carbon (SWCNTs) membrane as electrodes. The capacitors were cycled from 0 to 1V @ 10 A/g for 10,000 cycles with 99.9% coulombic efficiency and 94% energy efficiency, and 100% depth of discharge. The power performance of the aqueous symmetric SWCNTs membrane capacitor is almost 100 –1000 times better than commercial non-aqueous EDLC capacitors.
Mechanical Properties of Pillared-Graphene Nanostructures under Shear Loads
Authors: Sasaki H. , Hagi T. , Shintani K.
Published: April 2013

The shear deformations of pillared-graphene nanostructures are investigated using molecular dynamics simulation. Slight anisotropy regarding the direction of a shear load is detected. Changing the loading area in graphene and the radius of a single-walled carbon nanotube (SWNT) as a pillar, the deformations near the joints of graphene and a SWNT are examined in detail. It is concluded the anisotropy of the shear deformation of the nanostructure is due to the atomic structures at the joints of graphene and a SWNT as a pillar, and the out-of-plane deformations of graphene near the joints dominantly affect the overall shear deformation of the nanostructure.
Biaxially Stretchable Transparent Conductors That Use Metallic Single-Walled Carbon Nanotube Films
Authors: Ho Xinning , Tey Ju Nie , Liu Wenjun , Cheng Chek Kweng , Wei Jun
Published: April 2013

Transparent electronic devices that retain their electrical properties upon stretching and twisting are envisioned to be used in transparent wearable electronics and stretchable displays. An integral part of stretchable transparent electronic devices is the stretchable transparent conductor. In this work, we demonstrate biaxially stretchable transparent conductors that use metallic single-walled carbon nanotube films. Two dimensionally buckled metallic single-walled carbon nanotube films are realized. The “wavy” film “flattens out” when stretched and its electrical resistance hardly changes up to 3% applied strain. A similar film without any buckled structures suffers a severe degradation in electrical conductivity. Besides exhibiting stretchability, these transparent conductors display good sheet resistance (down to 3 kΩ/□) and transmittance (∼ 80% at a wavelength of 550 nm).
Concentrated Solutions of Highly Conductive Pyrene-Functionalized Carbon Nanotubes Suitable for Printing
Authors: Landorf Christopher William , Lamb James , Shih Wu-Sheng , Kayastha Vijaya , Bledsoe John , Garrison Jacqueline , Nelson Marriana
Published: April 2013

As produced, raw carbon nanotubes are not soluble in many solvents necessary for printing applications. Standard methods for circumventing this problem involve sidewall functionalization and surfactants. Sidewall functionalization invariably destroys the π-network that gives carbon nanotubes their useful electronic properties, while surfactants deposit an insulating layer onto the carbon nanotube surface that must be washed off to regain the desired properties. Non-covalent functionalization offers the possibility to achieve solubility without destroying the π-network, but published methods have resulted in relatively low concentrations or substandard electronic performance. We have developed a scalable method to non-covalently functionalize long (> 3 μm) carbon nanotubes with simple pyrene derivatives. This method produces highly dispersed solutions with concentrations as high as 2.5 g/l that can be used to produce conductive coatings with sheet resistance as low as 350 Ω/sq with 85% transmittance at 550 nm without post-deposition washing or doping treatments. The functionalized carbon nanotubes can be formulated into solutions that can be printed by ink-jet deposition, Aerosol-Jet® deposition, screen printing, and spray coating for printed electronics fabrication, and the solutions are stable for months without signs of bundling.
The effects of Pulsed Green Laser Annealing for Carbon NanoWalls (CNWs)
Authors: Kawaguchi Norihito , Yoshimura Akihiko
Published: April 2013

The effects of the pulsed green laser annealing at ambient nitrogen for two different heights-CNWs grown on silicon substrate were investigated on the crystallinity and morphology using Raman spectroscopy, SEM, TEM and XPS. For the 1μm height-CNWs, the peak intensity of D-band spectra decreased as the laser energy density increased up to 1.3Jcm-2, ID/IG ratio decreased from 2.5 to 0.7. The crystallinity of CNWs was improved by the laser irradiation. For the 1μm height-CNWs irradiated above 1.5Jcm-2, the height of CNWs decreased gradually as the laser energy density increased, it was clarified that the surfaces of CNWs were vaporized by the laser irradiation. For the 20μm height-CNWs, the peak intensity of D band spectra also decreased until the laser energy density increased up to 0.8Jcm-2, ID/IG ratio decreased from 1.6 to 0.5. From the TEM observation of CNWs irradiated at 0.8 Jcm-2, it was confirmed that the laser irradiation changed CNWs to be highly oriented crystal structure. However above 0.8Jcm-2, the crystallinity was deteriorated due to the vaporization of CNWs as the same as the 1μm height-CNWs. The pulsed green laser annealing is effective to improve the crystallinity of CNWs on optimal laser energy density for both height-CNWs, the higher laser energy densities vaporized the CNWs and changed the morphology and crystallinity of CNWs.
Solubility of Carbon in Nanocrystalline α-Iron
Authors: Kirchner Alexander , Eymann Konrad , Quadbeck Peter , Strauß Alexander , Kieback Bernd
Published: April 2013

By using a thermodynamic model of nanocrystalline alloys the grain size effect on the solubility of carbon in α-iron is calculated. More specifically the enrichment at grain boundaries is predicted to result in a solubility enhancement. An experimental setup is devised to measure carbon solubility in nanocrystalline iron powder in equilibrium with graphite. At 390 °C a solubility of 0.514 at% is determined for nanocrystalline iron with a grain size of 23 nm.
Fracture Patterns of Boron Nitride Nanotubes
Authors: Perim Eric , Santos Ricardo Paupitz , Autreto Pedro Alves da Silva , Galvao Douglas S.
Published: April 2013

During the last years carbon-based nanostructures (such as, fullerenes, carbon nanotubes and graphene) have been object of intense investigations. The great interest in these nanostructures can be attributed to their remarkable electrical and mechanical properties. Their inorganic equivalent structures do exist and are based on boron nitride (BN) motifs. BN fullerenes, nanotubes and single layers have been already synthesized. Recently, the fracture patterns of single layer graphene and multi-walled carbon nanotubes under stress have been studied by theoretical and experimental methods. In this work we investigated the fracturing process of defective carbon and boron nitride nanotubes under similar stress conditions. We have carried out fully atomistic molecular reactive molecular dynamics simulations using the ReaxFF force field. The similarities and differences between carbon and boron nitride fracture patterns are addressed.
Effects of Processing Parameters and Nanofillers on Mechanical and Thermal Properties and Morphology of Impact Modified Poly (lactic acid)
Authors: Acik Eda , Yilmazer Ulku
Published: April 2013

Ternary nanocomposites of poly (lactic acid) (PLA) were produced by melt blending with two types of elastomers and five types of organoclays to obtain improved mechanical properties such as tensile strength, modulus and impact strength. One of the elastomers is a random copolymer of ethylene and glycidyl methacrylate (E-GMA) and the other one is a random terpolymer of ethylene-butyl acrylate-maleic anhydride (E-BA-MAH). Organically modified montmorillonites (OMMT) were utilized as nanofillers. XRD, DSC, tensile and impact tests were done on the injection molded samples. FTIR, SEM and TEM analyses are still in progress. As preliminary results, thermal analysis showed that the addition of compatibilizers and organoclays does not have a distinct effect on the thermal properties of the composites, and no evidence of nucleation activity of compatibilizers or organoclays was found. For all types of organoclays, the nanocomposites produced with E-GMA exhibited better mechanical properties in comparison to nanocomposites containing E-BA-MAH, especially for the impact strength.
Microstructural Behavior of Energetic Crystalline Aggregates
Authors: LABARBERA D. , ZIKRY M.A.
Published: April 2013

A dislocation-density based crystalline plasticity and specialized finite-element formulations were used to study the behavior of energetic crystalline aggregates. The energetic crystalline material studied was RDX (cyclotrimethylene trinitramine) with a polymer binder and different void porosities. The aggregate was subjected to different dynamic pressures, and the analyses indicate that maximum temperature increases, constrained dislocation densities, and plastic strain accumulations occurred around the void peripheries, which affected overall deformation behavior. These regions of extreme temperature rise and thermal decomposition can result in hot spot formation.
Physical properties of La0.8Sr0.2MnO3nanotubes and fibers
Authors: Simião Daniel Felipe , Zenatti Alessandra , Escote Marcia T.
Published: April 2013

This work describes the study of synthesis and physical characterization of nanostructured manganite oxides. The La0.8Sr0.2MnO3 (LSM) nanotubes and fibers have been prepared by electrospinning and pore wetting technique. The samples were characterized by Xray diffraction (XRD), scanning electron microscopy (SEM) and magnetization as a function of temperature (M(T)). XRD results of LSM fibers and nanotubes revealed that both samples crystallize in a rhombohedra-distorted perovskite structure. SEM pictures of these samples revealed ultrafine grains assembled in fibers and nanotubes samples. Analysis of these images revealed samples with external diameter ranging from 300 to 1.4 mm, and 7 μm to hundreds of mm in length. The M(T) measurements of samples La0.8Sr0.2MnO3 revealed a paramagnetic/ferromagnetic transition with decreasing temperature. Such transition occurs at temperatures of Tc ≈ 337 K and Tc ≈ 360 K for the nanotubes and fibers, respectively. Furthermore, this variation of the Tc values is also reported in literature for other manganite nanostructures. Such variation can be related to the microstructural characteristics observed for both LSM samples produced in this work. In general, it is believed that both methodologies allowed the production of nanostructures LSM. Also, these results suggest that the dimensionality of the samples seems to interfere in the physical properties of LSM manganite.
Control of Volume Fraction of Non-180° Domains by Thermal Strain in Epitaxial Rhombohedral Pb(Zr, Ti)O3 Thick Films
Authors: Ehara Yoshitaka , Utsugi Satoru , Oikawa Takahiro , Yamada Tomoaki , Funakubo Hiroshi
Published: April 2013

Epitaxial rhombohedral Pb(Zr0.65Ti0.35)O3films with (100) and (110)/(10-1) and (111)/(11-1) orientations were grown on various kinds of singlecrystal substrates having different thermal expansion coefficient. Volume fractions of (110) and (111) orientations in respective (110)/(10-1) and (111)/(11-1)-oriented films were almost linearly increased with increasing thermal strain, εthermal, applied to the films that wasgenerated under the cooling process after the deposition from the growth temperature to the Curie temperature.Observed saturationpolarization (Psat)was changed linearly with the volume fractions of (110) and (111) orientations, in the same manner asthe volume fractions of (001) and (101) orientations in (001)/(100) and (101)/(110) oriented tetragonal Pb(Zr,Ti)O3 filmsreported previously. These results showed that the volume fraction of the non-180o domains Pb(Zr,Ti)O3films of both tetragonal and rhombohedral symmetriescan be manipulated by εthermal, which brings possibly to control the Psat value.
Carrier Transport Mechanisms in Metal-Insulator–Metal Au/Ba0.8Sr0.2TiO3/ ZrO2/ Ba0.8Sr0.2TiO3/Pt Thin Film Heterostructures
Authors: Sahoo Santosh K. , Bakhru H. , Kumar Sumit , Misra D. , Wolden Colin A. , Mohapatra Y. N. , Agrawal D. C.
Published: April 2013

Ba0.8Sr0.2TiO3/ZrO2 heterostructured thin films are deposited on Pt/Ti/SiO2/Si substrates by a sol-gel process. The current versus voltage (I-V) measurements of metal-insulator-metal (MIM) devices using the above multilayered thin film as the dielectric have been taken in the temperature range of 310 to 410K. The electrical conduction mechanisms contributing to the leakage current at different field regions have been studied in this work. Various models are used to know the different leakage mechanisms contributing to the conduction current in these devices. It is observed that Poole-Frenkel mechanism is the dominant conduction process in the high field region with a deep trap level energy (φt) of 1.31 eV whereas space charge limited current (SCLC) mechanism and Ohmic conduction process are contributing to the leakage current in the medium and low field regions respectively. The estimated shallow trap level (Et) for SCLC mechanism is 0.26 eV whereas the activation energy (Ea) for the electrons in the Ohmic conduction process is about 0.07 eV. An energy band diagram is given to explain the various leakage mechanisms in different field regions for these heterostructured thin films.
Silver Decorated Carbon Nanospheres as Effective Visible Light Photocatalyst
Authors: Armstrong W. , Sapkota B. , Mishra S. R.
Published: April 2013

The objective of this study was to assess usability of silver nanoparticles loaded on amorphous carbon (Ag-C) hollow nanospheres for the removal of Methylene Blue (MB) molecules from aqueous solutions. Using microwave technique, silver nanoparticles of different weight ratio was deposited onto amorphous carbon templates. The carbon hollow spheres were derived from glucose using hydrothermal technique. Interestingly crystallite size of Ag decreased with the silver loading on carbon nanospheres. Using UV-vis spectroscopy, the kinetics of MB removal from the solution was assessed. The degradation of MB followed pseudo-first-order kinetics. The obtained results showed that Ag-C particles are efficient MB degradation agent with the rate constant as high as 0.19 m-1 under visible light and 0.041 m -1 under UV light. Thus Ag-C particles are good alternative as low-cost scavenger of dye molecules in wastewater treatments.
Reduction of thermal conductivity in semiconducting composite films consisting of silicon and transition-metal silicide nanocrystals
Authors: Uchida N. , Ohishi Y. , Kurosaki K. , Yamanaka S. , Tada T. , Kanayama T.
Published: April 2013

We observed significant reduction of thermal conductivity in semiconducting composite films of Si and molybdenum (Mo)-silicide nanocrystals (NCs). These films were synthesized by phase separation due to annealing at 700 -1000°C from sputtered amorphous Mo–Si alloy. Transmission electron microscope images showed that the NCs were grown to diameters of∼10 nm in the films by annealing at 800°C. Raman scattering spectra showed lower shift of peak positions of Si transverse optical (TO) phonon due to the confinement effect and the tensile stress. The electrical resistivity of the films was 0.17- 9 Ωm at room temperature and showed a semiconducting temperature dependence at 20-400 K. Thermal conductivity of the film was reduced to 4.4 W/mK by enhancement of phonon scattering at NC interfaces, suggesting that the composite film is promising as a high-efficiency Si-based thermoelectric material.
Metabolic balances of sulfur in patients with hepatolenticular degeneration and effect of the use of D-penicillamine
Authors: Canelas Horacio M. , De Jorge Francisco B. , Tognola Waldir A.
Published: April 2013

The metabolic balances of sulfur in two cases of hepatolenticular degeneration were studied. A positive balance was found in both cases; in one patient submitted to mixed diet, the average was significantly higher than the normal mean. The administration of D-penicillamine promoted a marked increase in the urinary excretion of sulfur, leading to a strongly negative balance. The blood sulfur contents, which were normal in the control periods, showed a progressive increment after D-penicillamine was started.
O líquido cefalorraqueano no post-mortem
Authors: Spina-França A. , Cavallo Tito , Machado Aluizio de B. B. , Rocha A. Gama da , Galhardo Naide
Published: April 2013

Foi estudado o LCR de 45 cadáveres, sendo os resultados considerados em função do tempo decorrido entre o momento da morte e a colheita do LCR (TOC). Obedecendo a esse critério os casos foram assim grupados: 1) aqueles com TOC até 4 horas; 2) aqueles com TOC de 4 a 8 horas; 3) aqueles com TOC de 8 horas ou mais. Com o aumento do TOC a presença de hemácias no LCR de cadáveres se torna mais freqüente e mais intensa. A mistura de sangue ao LCR prejudica a avaliação das modificações cadavéricas de outros componentes do LCR, conforme foi demonstrado para as concentrações de cloretos glicose e proteínas totais, para o perfil protêico e para a atividade de transaminases. Assim sendo, para avaliar as modificações da composição do LCR próprias ao post-mortem devem ser considerados apenas os casos com menos de 1000 hemácias/mm³. O número normal de leucócitos foi proporcionalmente mais comum nas amostras provenientes de cadáveres cujo TOC era igual ou superior a 8 horas. A pleocitose foi observada com mais freqüência que o número normal de leucócitos, sendo mais comumente ligeira ou discreta. Quantidades superiores a 50 leucócitos/mm³ foram observadas geralmente em casos relativos a pacientes que faleceram na vigência de processos infecciosos agudos. As concentrações de cloretos e de glicose no LCR tendem a cair no postmortem e as diminuições mostraram-se, em média, tanto mais intensas quanto maior o TOC. A hipoglicorraquia foi, em média mais acentuada nos casos com pleoeitose mais intensa. A concentração de uréia tende a elevar-se de modo precoce, não tendo sido encontradas médias significativamente diversas em função do TOC. A atividade de TGO tende a elevar-se no post-mortem sendo esta elevação, em média, mais nítida a partir do grupo de casos com TOC de 4 até 8 horas. Ocorre também tendência a aumento da atividade de TGP; esta se mostrou menos intensa que a de TGO e, em média, foi mais nítida a partir do grupo de casos com TOC de 8 horas ou mais. A hiperproteinorraquia foi comum e mostrou, em média, tendência a acentuar-se com o aumento do TOC. O perfil protêico foi, geralmente, de tipo "misto", com aumento das globulinas alfa e/ou gama, compensado por queda do teor albumínico. O aumento dessas globulinas foi mais freqüente nos casos em que o óbito ocorreu na vigência de processos infecciosos. Nos casos com menos de 1000 hemácias/mm³ as modificações do perfil protêico, embora do mesmo tipo, eram menos acentuadas; em conjunto, houve predomínio das globulinas, especialmente das dos grupos alfa e gama. Em função do TOC foram verificadas discretas modificações do perfil protêico: com o aumento do TOC tendia a ser maior a participação da globulina gama e menor a da globulina beta. Os aspectos da composição do LCR aqui analisados permitem concluir que, 4 horas após a morte, já se delineiam modificações que caracterizam o LCR no post-mortem, sendo mais nítidas as relacionadas com o número de leucócitos e às concentrações de uréia, cloretos e glicose.
Derivação ventriculoperitoneal com válvula no tratamento da hidrocefalia do lactente
Authors: Almeida Gilberto Machado de , Pereira Walter C.
Published: April 2013

As derivações ventriculovenosas, se bem que tenham propiciado grande progresso no tratamento da hidrocefalia, não podem ser consideradas como solução definitiva do problema. Entre os vários inconvenientes que surgiram com estas técnicas, o embolismo e a fibrose pulmonares avultam entre os mais sérios, sendo suas conseqüências tardias ainda desconhecidas. Julgamos, portanto, justificada a busca de novas técnicas cirúrgicas ou o aprimoramento de outras já conhecidas. De dezembro de 1965 a março de 1969 empregamos a derivação ventriculoperitoneal com válvula em 110 doentes, 79 dos quais eram crianças com hidrocefalia. Nossos resultados permitiram verificar que, do ponto de vista mecânico, as derivações para a corrente sangüínea e para o peritônio funcionam de maneira semelhante, não sendo necessárias revisões freqüentes, como ocorria quando eram feitas drenagens para o peritônio sem válvula. Por outro lado, com as derivações ventriculoperitoneais evitamos a microembolia pulmonar; além disso as infecções no sistema de drenagem provocam quadro menos grave e de mais fácil solução que o observado nas ventrículo -atriostomias.