bluuebunny/crossref_metadata_2025 huggingface dataset:
Depolarization of Cochlear Outer Hair Cells Evokes Active Hair Bundle Motion by Two Mechanisms
Authors: Kennedy Helen J. , Evans Michael G. , Crawford Andrew C. , Fettiplace Robert
Published: March 2006

There is current debate about the origin of mechanical amplification whereby outer hair cells generate force to augment the sensitivity and frequency selectivity of the mammalian cochlea. To distinguish contributions to force production from the mechanotransducer (MET) channels and somatic motility, we have measured hair bundle motion during depolarization of individual outer hair cells in isolated rat cochleas. Depolarization evoked rapid positive bundle deflections that were reduced by perfusion with the MET channel blocker dihydrostreptomycin, with no effect on the nonlinear capacitance that is a manifestation of prestin-driven somatic motility. However, the movements were also diminished by Na salicylate and depended on the intracellular anion, properties implying involvement of the prestin motor. Furthermore, depolarization of one outer hair cell caused motion of neighboring hair bundles, indicating overall motion of the reticular lamina. Depolarization of solitary outer hair cells caused cell-length changes whose voltage-activation range depended on the intracellular anion but were insensitive to dihydrostreptomycin. These results imply that both the MET channels and the somatic motor participate in hair bundle motion evoked by depolarization. It is conceivable that the two processes can interact, a signal from the MET channels being capable of modulating the activity of the prestin motor.
Cocaine Self-Administration in Mice Is Inversely Related to Phosphorylation at Thr34 (Protein Kinase A Site) and Ser130 (Kinase CK1 Site) of DARPP-32
Authors: Zhang Y. , Svenningsson P. , Picetti R. , Schlussman S. D. , Nairn A. C. , Ho A. , Greengard P. , Kreek M. J.
Published: March 2006

The reinforcing effect of cocaine is associated with increases in dopamine in the striatum. The phosphoprotein DARPP-32 (dopamine- and cAMP-regulated phosphoprotein) has been shown to mediate the intracellular events after activation of dopamine receptors. DARPP-32 is phosphorylated at multiple sites by different protein kinases, but little is known about the functional role of these different sites. Cocaine self-administration and striatal levels of dopamine after acute “binge” cocaine administration were measured in separate lines of mice with alanine mutations introduced into DARPP-32 at either Thr34 (protein kinase A site, Thr34A), Thr75, (cyclin-dependent kinase 5 site, Thr75A), Ser97 (kinase CK2 site, Ser97A), or Ser130 (kinase CK1 site, Ser130A). Acquisition of stable cocaine self-administration required significantly more time in Thr34A−/− mice. Both Thr34A- and Ser130A-DARPP-32 mutant mice self-administered more cocaine than their respective wild-type controls. Also, cocaine-induced increases of dopamine in dorsal striatum were attenuated in the Thr34A- and Ser130A-DARPP-32 phosphomutant mice compared with wild-type mice. Notably, levels of P-Thr34- and P-Ser130-DARPP-32 were reduced after self-administration of cocaine in wild-type mice. Thus, phosphorylation states of Thr34- and Ser130-DARPP-32 play important roles in modulating the reinforcing effects of cocaine.
Gasping ActivityIn Vitro: A Rhythm Dependent on 5-HT2AReceptors
Authors: Tryba Andrew K. , Peña Fernando , Ramirez Jan-Marino
Published: March 2006

Many rhythmic behaviors are continuously modulated by endogenous peptides and amines, but whether neuromodulation is critical to the expression of a rhythmic behavior often remains unknown, particularly in mammals. Here, we address this issue in the respiratory network that was isolated in spontaneously rhythmic medullary slice preparations from mice. Under control conditions, the respiratory network generates fictive eupneic activity. We hypothesized previously that this activity depends on two types of pacemaker neurons. The bursting properties of one pacemaker rely on the persistent sodium current (INa(p)) and are insensitive to blockade of calcium channels with cadmium (CI-pacemakers), whereas bursting mechanisms of a second pacemaker are sensitive to cadmium (CS-pacemakers) and the calcium-dependent nonspecific cation current blocker flufenamic acid. During hypoxia, fictive eupneic activity is supplanted by the neural correlate of gasping, which is proposed to depend only on CI-pacemakers. Because CI-pacemakers require endogenous activation of 5-HT2Areceptors, we tested the hypothesis that 5-HT2Areceptor activation is critical for gasping. Here, we demonstrate that fictive gasping and CI-pacemaker bursting were selectively eliminated by the 5-HT2Areceptor antagonist piperidine or ketanserin. Neither 5-HT2Aantagonist eliminated bursting by CS-pacemakers and ventral respiratory group (VRG) population activity. However, this VRG activity was very different from eupneic activity. In the presence of 5-HT2Aantagonists, VRG activity was eliminated by flufenamic acid and could not be reliably restored by adding substance P. These data support the hypothesis that two types of pacemaker bursting mechanisms underlie fictive eupnea, whereas only one burst mechanism is critical for gasping.
Fine Temporal Properties of Center–Surround Interactions in Motion Revealed by Reverse Correlation
Authors: Tadin Duje , Lappin Joseph S. , Blake Randolph
Published: March 2006

Center–surround interactions are a key property of visual motion mechanisms. Using a temporal reverse correlation method with human observers, we investigated perceptual interactions between a brief center motion (∼20 ms) and a surround that moved up–down with a new direction chosen randomly every 5 ms. The aim was to reveal interactions between center and surround motions and their dependency on relative direction, contrast, and timing. Hypothesizing that surround computation involves different neural circuitry than the center response, we manipulated surround contrast to affect the relative timing of center and surround signals. The reverse correlation analysis yielded temporal profiles of surround influence indicating, in 5 ms steps, the time course of the effect of the surround on the discriminability of center motion. The resulting temporal profiles varied systematically with contrast: as surround contrast decreased, both the latency and duration of its influence increased. This finding, consistent with longer and variable neural response latencies at low contrast, psychophysically reveals fine-scale temporal interactions between center and surround signals. Additionally, the strength of surround influence was correlated with psychophysical thresholds for discriminating center motion. The directionality of this relationship, however, depended only on center contrast. When center motion was high contrast, poor direction discrimination was associated with an increased probability of same-direction surround motions. Low-contrast center motion, however, was more discriminable when surrounded by motion in the same direction, regardless of surround contrast. This suggests that the previously reported adaptive nature of center–surround interactions in motion is driven primarily by the visibility of the center motion signals.
Local Morphology Predicts Functional Organization of the Dorsal Premotor Region in the Human Brain
Authors: Amiez Céline , Kostopoulos Penelope , Champod Anne-Sophie , Petrides Michael
Published: March 2006

A confusing picture of the functional organization of the dorsal premotor region of the human brain emerged when functional neuroimaging studies that either examined visuomotor hand conditional activity or attempted to localize the human frontal eye field reported activity increases at the same general location, namely the junction of the superior precentral sulcus with the superior frontal sulcus. The present functional magnetic resonance imaging study examined visuomotor hand conditional activity and the locus of the frontal eye field as defined by a standard task, on a subject-by-subject basis, to clarify their location and reveal relationships between the pattern of local morphology and functional activity. The results demonstrate that visuomotor hand conditional activity and the frontal eye field lie within distinct parts of the superior precentral sulcus, revealing an organization of the human premotor cortex consistent with that observed in experimental studies in the monkey.
Region-Specific Reduction in Entorhinal Gamma Oscillations and Parvalbumin-Immunoreactive Neurons in Animal Models of Psychiatric Illness
Authors: Cunningham Mark O. , Hunt Jillian , Middleton Steven , LeBeau Fiona E. N. , Gillies Martin G. , Davies Ceri H. , Maycox Peter R. , Whittington Miles A. , Racca Claudia
Published: March 2006

Psychiatric illnesses, particularly schizophrenia, are associated with disrupted markers for interneuronal function and interneuron-mediated brain rhythms such as gamma frequency oscillations. Here we investigate a possible link between these two observations in the entorhinal cortex and hippocampus by using a genetic and an acute model of psychiatric illness. Lysophosphatidic acid 1 receptor-deficient (LPA1-deficient) mice show psychomotor-gating deficits and neurochemical changes resembling those seen in postmortem schizophrenia studies. Similar deficits are seen acutely with antagonism of the NMDA subtype of glutamate receptor. Neither model induced any change in power or frequency of gamma rhythms generated by kainate in hippocampal slices. In contrast, a dramatic decrease in the power of gamma oscillations was seen in superficial, but not deep, medial entorhinal cortex layers in both models. Immunolabeling for GABA, parvalbumin, and calretinin in medial entorhinal cortex from LPA1-deficient mice showed an ∼40% reduction in total GABA- and parvalbumin-containing neurons, but no change in the number of calretinin-positive neurons. This deficit was specific for layer II (LII). No change in the number of neurons positive for these markers was seen in the hippocampus. Acute NMDA receptor blockade, which selectively reduces synaptic drive to LII entorhinal interneurons, also disrupted gamma rhythms in a similar manner in superficial entorhinal cortex, but not in hippocampus. These data demonstrate an area-specific deficit in gamma rhythmogenesis in animal models of psychiatric illness and suggest that loss, or reduction in function, of interneurons having a large NMDA receptor expression may underlie the network dysfunction that is seen.
Prefrontal Cell Activities Related to Monkeys' Success and Failure in Adapting to Rule Changes in a Wisconsin Card Sorting Test Analog
Authors: Mansouri Farshad A. , Matsumoto Kenji , Tanaka Keiji
Published: March 2006

The cognitive flexibility to select appropriate rules in a changing environment is essential for survival and is assumed to depend on the integrity of prefrontal cortex (PFC). To explore the contribution of the dorsolateral PFC to flexible rule-based behavior, we recorded the activity of cells in this region of monkeys performing a Wisconsin Card Sorting Test (WCST) analog. The monkey had to match a sample to one of three test items by either color or shape. Liquid reward and a discrete visual signal (error signal) were given as feedback to correct and incorrect target selections, respectively. The relevant rule and its frequent changes were not cued, and the monkeys could find it only by interpreting the feedback. In one-third of cells, cellular activity was modulated by the relevant rule, both throughout the trial and between trials. The magnitude of the modulation correlated with the number of errors that the monkeys committed after each rule change in the course of reestablishing high performance. Activity of other cells differed between correct and error trials independently from the rule-related modulation. This difference appeared during actual responses and before the monkeys faced the problems. Many PFC cells responded to the error-signal presentation, and, in some of them, the magnitude of response depended on the relevant rule. These results suggest that the dorsolateral PFC contributes to WCST performance by maintaining the relevant rule across trials, assessing behavioral outcomes, and monitoring the processes that could lead to success and failure in individual trials.
Impaired Bidirectional Synaptic Plasticity and Procedural Memory Formation in Striatum-Specific cAMP Response Element-Binding Protein-Deficient Mice
Authors: Pittenger Christopher , Fasano Stefania , Mazzocchi-Jones David , Dunnett Stephen B. , Kandel Eric R. , Brambilla Riccardo
Published: March 2006

The striatum has a well documented role in procedural learning and memory. However, the synaptic and molecular mechanisms of acquisition and storage of this form of memory remain poorly understood. We examined procedural memory and plasticity in transgenic mice reversibly expressing a dominant-negative cAMP response element-binding protein (CREB) mutant in the dorsal striatum. In these transgenic mice, corticostriatal long-term potentiation and depression are abolished, indicating that CREB function is essential for bidirectional long-term synaptic plasticity in this structure. Importantly, CREB-deficient animals show reversible alterations in several forms of striatum-dependent memory, including footshock avoidance learning and “response” learning in the cross maze. These findings implicate transcriptional regulation by CREB family transcription factors in striatum-dependent information processing and provide the first clear correlation between procedural learning and memory and synaptic plasticity at the corticostriatal synapse.
Extraction of short-lived zirconium and hafnium isotopes using crown ethers: A model system for the study of rutherfordium
Authors: Sudowe Ralf , Calvert M.G. , Düllmann Ch. E. , Farina L. M. , Folden C. M. , Gregorich K. E. , Gallaher S. E. H. , Hoffman D. C. , Nelson S. L. , Phillips D. C. , Schwantes J. M. , Wilson R. E. , Zielinski P. M. , Nitsche Heino
Published: March 2006

The extraction of zirconium and hafnium from hydrochloric acid media was studied using the crown ethers dibenzo-18-crown-6 (DB18C6), dicyclohexano-18-crown-6 (DC18C6) and dicyclohexano-24-crown-8 (DC24C8) as extractants. The goal was to find an extraction system that exhibits a high selectivity between the members of group 4 of the periodic table and is suitable for the study of rutherfordium. It was found that Zr and Hf are both extracted using DB18C6, DC18C6 and DC24C8. The extraction yield increases with increasing acid concentration and increasing concentration of crown ether. The extracted species most likely consists of an ion-association complex formed between a Zr or Hf chloro complex and a hydronium crown ether complex. Conditions can be found for each extractant that provide for the separation of Zr from Hf. This selective separation between Zr and Hf makes the extraction with crown ethers from HCl well suited to study the extraction behaviour of Rf and compare it to the behaviour of Zr and Hf. These extraction systems can be used to determine whether the extraction behaviour of Rf is similar to Zr, similar to Hf or follows the trend established by the lighter homologs. The extraction kinetics are fast enough for the study of the 78-s isotope 261mRf.
Recovery of fission palladium by electrodeposition using room temperature ionic liquids
Authors: Giridhar P. , Venkatesan K. A. , Reddy B. P. , Srinivasan T. G. , Vasudeva Rao P. R.
Published: March 2006

Room temperature molten salts for possible application of recovery of fission palladium from irradiated nuclear fuel/wastes have been investigated. The redox behavior of a solution of palladium(II) chloride and 1-butyl-3-methylimidazolium chloride (bmimCl) at glassy carbon working electrode has been studied at various temperatures using cyclic voltammetry. The voltammogram of bmimCl-PdCl2consists of a single reduction and two oxidation waves indicating that Pd2+undergoes a single step two-electron quasi-reversible reduction process at the working electrode. Controlled potential deposition of palladium on platinum electrode gave a black deposit, which was characterized to be metallic palladium. Extraction of palladium by Aliquat-336 has been studied as a function of nitric acid concentration and the redox behavior of palladium in Aliquat-336 phase has been investigated by cyclic voltammetry. The results suggest that some aqueous insoluble room temperature ionic liquids can act both as extractant and electrolytic medium and also have the potential of recovering of palladium from nuclear wastes.
Sunflower stem: a novel and economical scavenger for Hg(II) ions from aqueous solutions and its kinetic and thermodynamic investigation
Authors: Malik Ummat Rasul , Hasany Syed Moosa , Subhani Muhammad Sadiq
Published: March 2006

The sorption of > 93% of Hg(II) ions is achieved onto sunflower stem (50 mg/4.5 cm3) from deionized water (D.W.) in 10 minutes equilibration time between two phases. The kinetics of sorption follows Reichenberg, Lagergren and Morris-Weber equations. The first order rate constant of sorption computed from Lagergren equation is 0.28 ± 0.01 min-1. The sorption data obey Dubinin–Radushkevich (D–R) and Freundlich isotherms. The Freundlich sorption capacity K
F = 13 ± 6 mmol g-1, 1/n = 0.68 ± 0.03 and D–R saturation capacity C
m = (2.9 ± 0.4)×102 μmol g-1, β = -0.0047 ± 0.0002 mol2 kJ-2 and mean free energy = 10.3 ± 0.2 kJ mol-1. The variation of sorption with temperature (293–318 K) gives ΔH = - 32 ± 2 kJ mol-1, ΔS = 123 ± 6 J mol-1 K-1, ΔG
298K = - 4.30 ± 0.05 kJ mol-1. Ascorbate, Sr(II) and Y(III) enhance the sorption whereas disufite, iodide, Cd(II), bisulfite and thiocyanate suppress the sorption. Selectivity studies indicate that Hg(II) ions can be separated from I(I) and Cs(I) using sunflower stem column. The sorbent may be used as a scavenger for the preconcentration of Hg(II) ions from its very dilute solutions or treatment of industrial and municipal effluents containing Hg(II) ions. A possible mechanism of biosorption of Hg(II) ions onto the sunflower stem is suggested.
Evaluation of cerium(IV) catalyzed remediation of plutonium contaminated soils at the Idaho Cleanup Project
Authors: Gombert Dirk , Karraker David , Drake Ron
Published: March 2006

An engineering and analytical chemical program was used to evaluate a proposed process to remove plutonium from contaminated soils at the Department of Energy's Idaho National Engineering and Environmental Laboratory Site. The design was based on the premise that the chemical process would be extremely efficient, reducing up to 250 nCi/g total transuranic contamination including both plutonium, in several chemical forms, and americium to less than 10 nCi/g. To ensure the effectiveness of the process on even heat-treated forms of plutonium, a very aggressive cerium IV catalyzed hot nitric acid leach step was used. Laboratory experiments showed that the chemistry could indeed remove plutonium, but due to the secondary wastes generated by coincident dissolution of the soil matrix, the process did not meet other design requirements.
Introduction: The Archaeology of Childhood in Context
Authors: Baxter Jane Eva
Published: March 2006

This introductory chapter contextualizes the volume contents within broader themes and histories in the archaeological and anthropological study of childhood. Some of these broader issues include how archaeologists have situated childhood studies within the discipline, how archaeologists have identified children through the archaeological record, and how the archaeological study of childhood leads to interdisciplinary conversations across the subfields.
Constructing an Archaeology of Children: Studying Children and Child Material Culture from the African Past
Authors: Bugarin Flordeliz T.
Published: March 2006

This chapter addresses the implications of an archaeology that includes studies of children and their material environment. Focusing on examples of African populations, it offers models that contribute to theories about child behavior. The construction of an archaeology of children is feasible and important for furthering our understanding of the past. Through ethnoarchaeological approaches, we have the opportunity to begin a discourse on children and to set a foundation for future studies on what the children left behind.
Making Space for Children in Archaeological Interpretations
Authors: Baxter Jane Eva
Published: March 2006

Childhood is a prolonged period of dependence during which children mature physically and acquire the cultural knowledge necessary to become accepted members of a society. Members of every culture create and define “children” through the process of socialization, whereby children are taught “acceptable” roles, practices, beliefs, and values by their families, peers, and communities. Socialization creates a culturally specific framework for children's behavior, including their use of space. The process of socialization also relies on material culture as a means to symbolically reinforce messages about proper behaviors, roles, and values. These factors make it possible to study the process of socialization through the archaeological record. A recent comparative study of archaeological data from five 19th‐century domestic sites has been used (1) to demonstrate empirically that children produce structured artifact distributions in the archaeological record and (2) to demonstrate that behavioral patterns and artifact types may be used to investigate how children were socialized in past cultures. The results of this research have wide‐ranging implications for studying the distribution of material culture and interpreting site‐formation processes at both historic and prehistoric sites. This chapter presents an overview of this research with an emphasis on the theoretical and methodological basis for linking childhood socialization to the material record. Particularly, this chapter introduces a methodology for recovering and interpreting evidence related to children in behavioral, nonmortuary contexts in the archaeological record. While the case study is from 19th‐century America, the methodologies are presented to emphasize their applicability in other archaeological contexts, both historic and prehistoric.
Redefining Childhood through Bioarchaeology: Toward an Archaeological and Biological Understanding of Children in Antiquity
Authors: Perry Megan A.
Published: March 2006

Many critiques surrounding the archaeology of childhood have addressed the disparate social and biological identifications of children. Bioarchaeological information can elucidate the lives of children and the meaning of childhood in antiquity. Bioanthropological techniques additionally can identify biological developmental stages of childhood that may link to socially defined age grades. This chapter presents and critically evaluates the diverse techniques that may be used to illuminate relationships between biological evidence and social interpretations in the archaeological study of children and childhood. A brief example from the Byzantine Near East illustrates the utility of bioarchaeology in the study of ancient children.
Synthesis and electrochemical properties of InP nanocrystals
Authors: Kumar Sandeep , Thomann Ralf , Nann Thomas
Published: March 2006

In this report, we present a new organometallic synthetic method to prepare nearly monodisperse InP nanoparticles using indium trifluoroacetate as the In precursor. Spherical particles of various sizes were prepared by modulating the growth duration. The optical and electrochemical properties were investigated and discussed with reference to band edge positions. This is the first report on the band edge position of quantum confined InP nanoparticles, which is a key parameter for development of electro-optic devices like solar cells and light-emitting diodes based on it.
Robust quantum-based interatomic potentials for multiscale modeling in transition metals
Authors: Moriarty John A. , Benedict Lorin X. , Glosli James N. , Hood Randolph Q. , Orlikowski Daniel A. , Patel Mehul V. , Söderlind Per , Streitz Frederick H. , Tang Meijie , Yang Lin H.
Published: March 2006

First-principles generalized pseudopotential theory (GPT) provides a fundamental basis for transferable multi-ion interatomic potentials in transition metals and alloys within density-functional quantum mechanics. In the central body-centered cubic (bcc) metals, where multi-ion angular forces are important to materials properties, simplified model GPT (MGPT) potentials have been developed based on canonical d bands to allow analytic forms and large-scale atomistic simulations. Robust, advanced-generation MGPT potentials have now been obtained for Ta and Mo and successfully applied to a wide range of structural, thermodynamic, defect, and mechanical properties at both ambient and extreme conditions. Selected applications to multiscale modeling discussed here include dislocation core structure and mobility, atomistically informed dislocation dynamics simulations of plasticity, and thermoelasticity and high-pressure strength modeling. Recent algorithm improvements have provided a more general matrix representation of MGPT beyond canonical bands, allowing improved accuracy and extension to f-electron actinide metals, an order of magnitude increase in computational speed for dynamic simulations, and the development of temperature-dependent potentials.
Electron energy-loss spectroscopy study of a multilayered SiOx and SiOxCy film prepared by plasma-enhanced chemical vapor deposition
Authors: Zhang Zaoli , Wagner Thomas , Sigle Wilfried , Schulz Andreas
Published: March 2006

A multilayered structure of SiOx and SiOxCy on silicon substrate was prepared by plasma-enhanced chemical vapor deposition from gas mixtures of hexamethyldisiloxane and oxygen. Scanning transmission electron microscopy studies showed that the structure is well defined with distinct layers. The distributions of Si, C, and O were measured via electron energy-loss spectroscopy. We found that the elements C, Si, and O interdiffuse quite differently across the interfaces. The Si–L2,3 energy-loss near-edge structures in the SiOx and SiOxCy layers were different from those of pure Si, SiC, and Si3N4, which all contain a tetrahedral structure unit. Slight variations of the relative ratio of the first two sharp peaks at about 108 and 115 eV were found, which can probably be attributed to C partially substituting O atoms in the Si–O tetrahedral structure.
Identification of viscoplastic material parameters from spherical indentation data: Part I. Neural networks
Authors: Tyulyukovskiy E. , Huber N.
Published: March 2006

In this paper, a new method for the identification of material parameters is presented. Neural networks, which are trained on the basis of finite element simulations, are used to solve the inverse problem. The material parameters to be identified are part of a viscoplasticity model that has been formulated for finite deformations and implemented in the finite element code ABAQUS. A proper multi-creep loading history was developed in a previous paper using a phenomenological model for viscoplastic spherical indentation. Now, this phenomenological model is replaced by a more realistic finite element model, which provides fast computation and numerical solutions of high accuracy at the same time. As a consequence, existing neural networks developed for the phenomenological model have been extended from a power law hardening with two material parameters to an Armstrong–Frederick hardening rule with three parameters. These are the yield stress, the initial slope of work hardening, and maximum hardening stress of the equilibrium response. In addition, elastic deformation is taken into account. The viscous part is based on a Chaboche-like overstress model, consisting of two material parameters determining velocity dependence and overstress as a function of the strain rate. The method has been verified by additional finite element simulations. Its application for various metals will be presented in Part II, [J. Mater. Res.21, 677 (2006)].
Textures and compressive properties of ferromagnetic shape-memory alloy Ni48Mn25Ga22Co5 prepared by isothermal forging process
Authors: Wang Y.D. , Cong D.Y. , Peng R. Lin , Zetterström P. , Zhang Z.F. , Zhao X. , Zuo L.
Published: March 2006

A ferromagnetic shape-memory alloy Ni48Mn25Ga22Co5 was prepared by the induction melting and isothermal forging process. Dynamic recrystallization occurs during the isothermal forging. The deformation texture was studied by the neutron diffraction technique. The main texture components consist of (110)[112] and (001)[100], which suggested that in-plane plastic flow anisotropy should be expected in the as-forged condition. The uniaxial compression fracture strain in the forged alloy reaches over 9.5%. The final room-temperature fracture of the polycrystalline Ni48Mn25Ga22Co5 is controlled mainly by intergranular mode.
Surface oxides and their effect on the oxidation behavior of amorphous and nanoquasicrystalline Zr–Pd and Zr–Pt alloys
Authors: Mondal K. , Chatterjee U.K. , Murty B.S.
Published: March 2006

The oxidation behavior of melt-spun Zr75Pd25 and Zr80Pt20 alloys with nanoquasicrystalline phase embedded in amorphous matrix has been studied isothermally as well as nonisothermally in static air. The nature of oxides formed during oxidation has been studied by x-ray diffraction and scanning electron microscopy, and a transition in the structure of the oxides has been shown as one of the primary reasons for the difference in the oxidation behavior of the alloys.
Effect of electromigration on mechanical shear behavior of flip chip solder joints
Authors: Nah Jae-Woong , Ren Fei , Paik Kyung-Wook , Tu K.N.
Published: March 2006

Effect of electromigration on mechanical shear behavior of flip chip solder joints consisting of 97Pb3Sn and 37Pb63Sn composite solder joints was studied. The under bump metallurgy (UBM) on the chip side was TiW/Cu/electroplated Cu, and the bond pad on the board side was electroless Ni/Au. It was found that the mode of shear failure has changed after electromigration and the mode depends on the direction of electron flow during electromigration. The shear induced fracture occurs in the bulkof 97Pb3Sn solder without current stressing, however, after 10 h current stressing at 2.55 × 104 A/cm2 at 140 °C, it occurs alternately at the cathode interfaces between solder and intermetallic compounds (IMCs). In the downward electron flow, from the chip to substrate, the failure site was at the Cu–Sn IMC/solder interface near the Si chip. However, in the upward electron flow, from the substrate to chip, failure occurred at the Ni–Sn IMC/solder interface near the substrate. The failure mode has a strong correlation to microstructural change in the solder joint. During the electromigration, while Pb atoms moved to the anode side in the same direction as with the electron flow, Sn atoms diffused to the cathode side, opposite the electron flow. In addition, electromigration dissolves and drives Cu or Ni atoms from UBM or bond pad at the cathode side into the solder. These reactions resulted in the large growth of Sn-based IMC at the cathode sides. Therefore, mechanical shear failure occurs predominantly at the cathode interface.
Mechanical properties of AZ31 Mg alloy recycled by severe deformation
Authors: Chino Yasumasa , Hoshika Tetsuji , Lee Jae-Seol , Mabuchi Mamoru
Published: March 2006

AZ31 Mg machined chips were recycled by extrusion at 673 K with a low extrusion ratio of 45:1 and a high extrusion ratio of 1600:1. Oxide contaminants were dispersed more uniformly in the recycled specimen with the high extrusion ratio than in that with the low extrusion ratio. In tensile tests, the recycled specimens with the high extrusion ratio showed about 50% higher 0.2% yield stress and about 20% higher tensile strength compared with those of the reference specimens, which were the extruded AZ31 Mg blocks under the same conditions as the recycled specimens. The improvement of the tensile properties was attributed not only to the small grain size, but also to the dispersed oxide contaminants.
Large-grain poly-crystalline silicon thin films prepared by aluminum-induced crystallization of sputter-deposited hydrogenated amorphous silicon
Authors: Hossain Maruf , Meyer Harry M. , Abu-Safe Husam H. , Naseem Hameed , Brown W.D.
Published: March 2006

A metal-induced crystallization (MIC) technique was used to produce large-grain poly-crystalline silicon. Two sets of samples were prepared by first sputtering Al onto glass substrates. For one set of samples, hydrogenated amorphous silicon (a-Si:H) was sputtered on top of the Al without breaking the vacuum. For the second set, the samples were taken out of the vacuum chamber and exposed to the atmosphere to grow a very thin layer of native aluminum oxide before sputter depositing the a-Si:H. Both sets of samples were then annealed at temperatures between 400 and 525 °C for 40 min. X-ray diffraction patterns confirmed the crystallization of the samples. Scanning Auger microanalysis was used to confirm that the a-Si:H and Al layers exchanged positions in this structure during the crystallization process. Auger mapping revealed the formation of large grain poly-silicon (10–20 μm). A model is proposed to explain how the crystallization process progresses with anneal temperature.
Combustion synthesis of AlN with melamine as an additive
Authors: Shim Gunchoo , Park Je-Shin , Cho Sung-Wook
Published: March 2006

Melamine (C3H6N6) was used as an additive for synthesizing aluminum nitride by combustion synthesis. It was found that at least 0.1 M of melamine addition to 1 M of aluminum and 0.8 MPa of nitrogen pressure were necessary to initiate a stable reaction. In addition to melamine, however, use of aluminum nitride as a diluent and application of forced nitrogen flow yielded better results. Analyzing the reaction temperatures, reaction rates, nitrogen contents, x-ray diffraction patterns, and scanning electron microscopy photographs, the optimum conditions for synthesizing AlN were established: (i) reactants were 90 wt% (1 M Al + 0.1 M melamine) + 10 wt% AlN diluent, (ii) chamber pressure was 0.9 MPa, and (iii) nitrogen flow rate was 15 l/min. Under these conditions, aluminum nitride with the stoichiometric nitrogen content of 34 wt% could be obtained.
Deformation and failure of a film/substrate system subjected to spherical indentation: Part II. Prediction of failure modes in a thin TiN film deposited on a compliant elastic substrate
Authors: Math S. , Jayaram V. , Biswas S.K.
Published: March 2006

We have demonstrated previously, using nanoindentation, that the film thickness and substrate plasticity, the important two external variables in the film layer, control the failure of the film in a mutually exclusive way. In this work, we used a non-iterative Hankel transform method to analyze the stresses in an elastic film bound to an elastic substrate by a no-slip boundary condition and subjected to a Hertzian traction. We vary the substrate compliance by two orders of magnitude to generate interfacial mismatch stresses, which mimic the corresponding changes found in a real-life elastic film on an elastic-plastic substrate when the hardness of the substrate is changed. The analysis is found to reproduce faithfully the experimental trends, which showed that normal load and interfacial stresses generated by strain mismatch drive different modes of fracture depending on the film thickness in a mutually exclusive way. This validation paves the way for this theoretical technique to be used to design multilayered film structures.
Viscoelastic behavior of a soda-lime-silica glass in the 293–833 K range by micro-indentation
Authors: Shang Haixia , Rouxel Tanguy , Buckley Marc , Bernard Cedric
Published: March 2006

The viscoelastic behavior of a soda-lime silica glass (a standard window glass) was investigated by means of Vickers indentation from room temperature to 833 K. Hardness values decrease gradually from 293 to 673 K and drop rapidly above 673 K. The flow kinetics of the glass at high temperature was analyzed in the light of atomic force microscopy observations. It was observed that densification significantly contributes to the permanent deformation at low temperatures, whereas volume conservative flow played a more and more important role as temperature was increased. Master curves of the relaxation modulus and the creep compliance were obtained from constant-rate and constant-load indentation experiments, respectively. A major finding was that the viscous flow process is nonlinear, with a sharp decrease of the apparent viscosity as the mean contact pressure increases.
Fabrication of c-axis oriented polycrystalline ZnO by using a rotating magnetic field and following sintering
Authors: Tanaka Satoshi , Makiya Atsushi , Kato Zenji , Uchida Nozomu , Kimura Tsunehisa , Uematsu Keizo
Published: March 2006

We succeeded in fabricating c-axis (00l) oriented ZnO ceramics by using a rotating magnetic field and a subsequent sintering treatment. The degree of orientation in the green compact was about 0.5 along (00l) on the Lotgering scale. The degree of orientation increased to 0.99 after sintering at 1573 K. Particles can also be oriented in a static magnetic field, but along the direction of the a-axis or a,b-axes (h00), (hk0). These results show that selected axes can be oriented by controlling the magnetic field. Control of the crystal form in microstructures is expected to result in improvements in and better miniaturization of functional ceramics.
Deposition of rare earth tantalate buffers on textured Ni-W substrates for YBCO coated conductor using chemical solution deposition approach
Authors: Bhuiyan M.S. , Paranthaman M. , Goyal A. , Heatherly L. , Beach D.B.
Published: March 2006

Epitaxial films of rare-earth (RE = La, Ce, Eu, and Gd) tantalates, RE3TaO7 with pyrochlore structures were grown on biaxially textured nickel-3 at.% tungsten (Ni-W) substrates using chemical solution deposition (CSD) process. Precursor solution of 0.3∼0.4 M concentration of total cations were spin coated on to short samples of Ni-W substrates and the films were crystallized at 1050∼1100 °C in a gas mixture of Ar- 4% H2 for 15 to 60 min. X-ray studies show that the films of pyrochlore RE tantalate films are highly textured with cube-on-cube epitaxy. Improved texture was observed in case of lanthanum tantalate (La3TaO7) film grown on Ni-W substrates. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) investigations of RE3TaO7 films reveal a fairly dense and smooth microstructure without cracks and porosity. The rare-earth tantalate layers may be potentially used as buffer layers for YBa2Cu3O7-δ (YBCO) coated conductors.
Erratum: “Compositional tailored sol-gel SiO2-TiO2 thin films: Crystallization, chemical bonding configuration, and optical properties” [J. Mater. Res. 20, 3141 (2005)]
Authors: Yang Li-Lan , Lai Yi-Sheng , Chen J.S. , Tsai P.H. , Chen C.L. , Chang C. Jason
Published: March 2006

The affiliations for the authors were cited incorrectly in the November 2005 issue of the Journal of Materials Research. The correct affiliations appear above. The printer regrets this error.
Conversational Skills of Children with Cleft Lip and Palate: A Replication and Extension
Authors: Frederickson Melissa S. , Chapman Kathy L. , Hardin-Jones Mary
Published: March 2006

Objective

To replicate and to extend a previous study examining the conversational skills of children with cleft lip and palate.

Participants

Thirty-four children (33 to 44 months) participated: 17 children with cleft lip and palate and 17 noncleft children.

Methods

The children were observed during an interaction with caregivers in their homes. Samples of caregiver-child interactions were coded as assertive or responsive, for type of conversational act, and for discourse level categories. Profiles of conversational activity were determined for each child based on the coding. Correlations were performed to examine the relationship between assertiveness and speech variables (articulation and resonance) for the children with cleft lip and palate.

Results

Group comparisons revealed that the children with cleft lip and palate produced fewer assertive utterances, were less likely to respond adequately to comments by caregivers, and produced more topic maintaining and fewer topic extending utterances than did their noncleft peers during conversational interactions. Examination of individual child data indicated that 35% of the children with cleft lip and palate exhibited conversational profiles characterized by either low assertiveness or low responsiveness. Finally, a significant positive correlation was noted between conversational assertiveness and speech production skills.

Conclusion

These findings suggested that the children with cleft lip and palate were less conversationally assertive than their noncleft peers. Further, there appeared to be a relationship between speech production skills and conversational skills, suggesting that poor speech may be impacting language performance for these children.
Early Postnatal Development of the Mandible in Children with Isolated Cleft Palate and Children with Nonsyndromic Robin Sequence
Authors: Eriksen J. , Hermann N. V. , Darvann T. A. , Kreiborg S.
Published: March 2006

Objective

Analysis of early postnatal mandibular size and growth velocity in children with untreated isolated cleft palate (ICP), nonsyndromic Robin sequence (RS), and a control group of children with unilateral incomplete cleft lip (UICL).

Material

114 children (66 isolated cleft palate, 7 Robin sequence, 41 unilateral incomplete cleft lip) drawn from a group representing all Danish cleft children born from 1976 through 1981. All children were examined at both 2 and 22 months of age.

Methods

Cephalometric x-rays and maxillary plaster casts. Mandibular length and height were measured and mandibular growth velocity (mm/year) was calculated. Cleft width was measured on the casts at 2 months of age.

Results

Mean mandibular length and posterior height were significantly smaller in isolated cleft palate and Robin sequence, compared with unilateral incomplete cleft lip. Mandibular length in Robin sequence was also significantly shorter, compared with isolated cleft palate. No significant difference was found between mean mandibular growth velocities in the three groups. No significant correlation was found between mandibular length and cleft width in either isolated cleft palate or Robin sequence at 2 months of age.

Conclusion

The children with isolated cleft palate and Robin sequence had small mandibles shortly after birth, but with a relatively normal growth potential. No true mandibular catch-up growth was found up to 22 months of age in either group. No significant correlation was found between mandibular size and cleft width in either group at 2 months of age. However, there was a significant trend toward the shorter the mandible, the more severe the sagittal extension of the cleft.
Epignathus: Large Obstructive Teratoma Arising from the Palate
Authors: Halterman Sandra M. , Igulada Kristen N. , Stelnicki Eric J.
Published: March 2006

Objective

This report describes an interesting case providing a brief review of the literature and highlighting the complexity in management and definitive treatment of a premature neonate with an obstructive epignathus teratoma and polydactyly bilaterally. Additionally, this case is unique because of the extremely large size of the oral tumor in relation to the neonate's total body size.
Prediction of Deterioration of Velopharyngeal Function Associated with Maxillary Advancement Using Electromyography of Levator Veli Palatini Muscle
Authors: Nohara Kanji , Tachimura Takashi , Wada Takeshi
Published: March 2006

Objective

The purpose of the present study was to examine the possibility that postoperative velopharyngeal function following maxillary advancement could be predicted using preoperative electromyography of the levator veli palatini.

Design

Levator muscle electromyography was recorded preoperatively during speech and blowing. Levator activity was expressed as a percentage relative to the maximum value observed throughout the experiment. Postoperative velopharyngeal function was evaluated by means of perceptual judgment and nasoendoscopy.

Participants

The subjects were four patients with repaired cleft palates who underwent maxillary advancement, two by osteotomy and two by distraction osteogenesis. None of the subjects presented with preoperative hypernasality, and nasoendoscopy demonstrated complete velopharyngeal closure in all subjects prior to maxillary advancement.

Results

Preoperative levator activity for speech of two subjects was similar to that for normal speakers (<60% of total range), and postoperative nasality and nasoendoscopic findings revealed no detectible changes. For the other two subjects, levator activity for speech exceeded 60% of the total range, similar to that of speakers with velopharyngeal incompetence. These subjects showed increased hypernasality and deteriorated velopharyngeal closure following maxillary advancement.

Conclusion

The deterioration of velopharyngeal function associated with maxillary advancement was demonstrated for subjects whose levator activity was at higher levels during speech in comparison with maximal activity observed during blowing, regardless of the amount of maxillary advancement. Preoperative levator muscle electromyography could be a predictor in identifying patients at higher risk of postsurgical deterioration of velopharyngeal function.
Blepharo-Cheilo-Dontic (BCD) Syndrome: Case Report
Authors: Iida Akihiko , Narai Shota , Takagi Ritsuo , Ono Kazuhiro , Ikeda Nobuyuki
Published: March 2006

Objective

To report a case of blepharo-cheilo-dontic (BCD) syndrome, to compare with the previous cases, and to discuss the possible treatment.

Patient

The patient was a 14-day-old boy born uneventfully on August 7, 2002. His scalp hair was sparse and curly. A tumor on the top of his head, which was thought to be a dermoid cyst, and a nevus on the back of his left hand were observed. All typical symptoms of blepharo-cheilo-dontic syndrome, such as euryblepharon with ectropion of the lower eyelids, distichiasis, bilateral cleft lip and palate, severe oligodontia, and conical teeth, were observed. Because there was no fatal complication, and growth and development were about normal, it was recommended that a long and active treatment plan be considered for this patient.
A Novel Mutation in EFNB1, Probably with a Dominant Negative Effect, Underlying Craniofrontonasal Syndrome
Authors: Shotelersuk Vorasuk , Siriwan Pichit , Ausavarat Surasawadee
Published: March 2006

Craniofrontonasal syndrome (CFNS) is an X-linked disorder whose main clinical manifestations include coronal craniosynostosis and frontonasal dysplasia. Very recently, CFNS was shown to be caused by mutations in EFNB1 encoding ephrin-B1, and 20 mutations have been described. We report a Thai woman with CFNS, in whom a novel mutation was discovered: c.685_686insG, in exon 5 of EFNB1. It is the first insertion and the most 3′ point mutation in EFNB1 reported to date. The mutation is expected to result in a truncated ephrin-B1 of 230 amino acids, composed of a nearly complete extracellular part of ephrin-B1 with no transmembrane and cytoplasmic domains. This truncated protein might become a soluble form of the ligand, which previously was shown to be able to bind to receptors, but fail to cluster and to activate them—in other words, acting as a dominant negative protein. Nonetheless, further studies to detect the protein are needed to substantiate the hypothesis.