bluuebunny/crossref_metadata_2025 huggingface dataset:
Modulation by epidermal growth factor – urogastrone of contraction in isolated canine helical mesenteric arterial strips
Authors: Muramatsu I. , Hollenberg M. D. , Lederis K.
Published: April 2011

We have examined the effect of epidermal growth factor – urogastrone (EGF–URO) on the response of isolated canine helical mesenteric arterial strips contracted by norepinephrine (NE), KCl, and transmural electrical stimulation (TES). Although EGF–URO alone did not affect resting arterial tone, contraction caused by all three modes of stimulation (NE, KCl, and TES) was inhibited up to 50% in the presence of EGF-URO. The action of EGF–URO did not depend on the presence of intact endothelial cells. The most pronounced effect of EGF-URO was observed on KCl-mediated contraction. The inhibitory effect of EGF-URO was maximal at about 15 min after addition of the polypeptide to the organ bath and persisted (e.g., electrical stimulation) for up to 1 h. A half-maximal inhibitory effect of EGF–URO was observed at a concentration of about 1 nM. Washing the tissue free of EGF–URO reversed its inhibitory action. Although in the presence of indomethacin (3 μM) EGF–URO caused a small, variable elevation in resting tension, the presence of indomethacin did not affect the ability of EGF–URO to inhibit contraction mediated by KCl. Under conditions wherein contraction in response to maximally effective concentrations of either NE or KCl was made dependent on the addition of calcium, EGF–URO was able to inhibit the response in the presence of KCl but not in the presence of NE. We conclude that EGF–URO can reduce the responsiveness of canine mesenteric arterial tissue to a variety of stimulants via a mechanism that does not involve the participation of either intact endothelial cells or products of the prostaglandin synthetase pathway.
Phasic influences of vagal stimulation on atrioventricular conduction
Authors: Warner Margaret R. , Loeb Jerod M.
Published: April 2011

The beat-by-beat changes in atrioventricular (AV) conduction evoked by constant frequency and phase-coupled vagal stimulation were examined both qualitatively and quantitatively in 13 anesthetized dogs. The effects of pacing cycle length and sympathetic activity on the vagally induced phasic changes in AV conduction were also characterized. When the vagal stimulus interval was nearly equal to the pacing cycle length and the vagal stimulus moved progressively through the cardiac cycle, AV interval oscillated in a rhythmic fashion. The rhythmicity of the vagally induced AV interval oscillations was altered substantially by changes in either the vagal stimulus interval or the pacing cycle length. The vagally induced AV interval oscillations were abolished during phase-coupled vagal stimulation; however, the magnitude of the resultant steady-state AV interval depended on the time relative to the phase of the cardiac cycle that the vagal stimulus was delivered. In the presence or absence of sympathetic stimulation, a vagal stimulus falling approximately 200 ms prior to atrial depolarization evoked the greatest prolongation in AV interval, regardless of the pacing cycle length. Additionally, the effects of combined sympathetic and phase-dependent vagal stimulation on the AV interval were additive. These data confirm that the influence of a vagal stimulus on AV interval can be predicted from the phase in the cardiac cycle that the vagal stimulus is delivered. Moreover, this phase dependency of vagal effects evokes marked qualitative variations in AV interval response patterns when either the vagal stimulus interval or the pacing cycle length is altered.
Metabolism of 3-methylindole by prostaglandin H synthase in ram seminal vesicles
Authors: Formosa P. J. , Bray T. M. , Kubow S.
Published: April 2011

3-Methylindole (3MI) causes a highly tissue- and species-selective lesion of the lung. Metabolic activation of 3MI by the NADPH-dependent mixed function oxidase (MFO) system is the initial event in the lung-specific toxicity. One-electron co-oxidation of 3MI by prostaglandin H synthase (PHS) has been implicated as an alternative mechanism for toxicity in the lung that contains high PHS activity. The objective of this study was to determine if 3MI can be co-oxidized by the arachidonic acid dependent PHS complex. Ram seminal vesicle (RSV) microsomes,which lack MFO activity, were used as a source of PHS. Incubations of RSV microsomes with 3MI, at a concentration as low as 0.01 mM, showed an increase in PHS activity, as indicated by an enhanced rate of oxygen consumption. This effect was arachidonic acid dependent and was inhibited (98%) by indomethacin. Addition of 3MI resulted in a concentration-dependent increase in PHS-catalyzed prostaglandin biosynthesis from [14C]arachidonic acid. PHS-dependent oxidative metabolism of [14C]3MI resulted in a twofold increase in ethyl acetate extracted radiolabelled metabolites. ESR spin-trapping studies demonstrated the presence of a 3MI free radical generated from the metabolism of 3MI by horseradish peroxidase, a model system of PHS hydroperoxidase. The results indicate that 3MI can be co-oxidized by the arachidonic acid-dependent PHS complex. Co-oxidation of 3MI by PHS may play a role in the tissue specificity of 3MI-induced pneumotoxicity.
Critical period programming of intestinal glucose transport via alterations in dietary fatty acid composition
Authors: Keelan M. , Thomson A. B. R. , Garg M. L. , Clandinin M. T.
Published: April 2011

Intestinal adaptation occurs in response to physiological or pathological processes that include resection, aging, diabetes, radiation, lactation, chronic alcohol feeding, and feeding diets of varying lipid, protein, or carbohydrate composition. The mechanisms involved in the adaptive response include alterations in morphology, cell kinetics, digestive enzyme activity, transport, membrane lipid composition, and enzymes involved in lipid metabolism. This discussion will review the effect of aging and alterations in dietary fatty acid composition on the small intestine. In addition, it may be possible to program the intestinal response to aging by feeding diets of differing fatty acid composition during the critical period of weaning. Alterations in the ratio of polyunsaturated to saturated fatty acids in the diet modifies the age-associated changes in the intestinal uptake of glucose. The changes occur rapidly, progressively, and irreversibly, suggesting that the intestinal uptake of glucose is subject to critical period programming. The mechanism by which diet may modify the ability of the intestine to up- or down-regulate glucose transport requires further investigation.Key words: polyunsaturated fatty acids, intestinal glucose transport, adaptation, diet, aging.
Serial natriuretic response to atrial peptide in preascitic bile duct ligated dogs
Authors: Maher Elizabeth , Cernacek Peter , Levy Mortimer
Published: April 2011

We determined if nine precirrhotic unanaesthetized dogs with chronic bile duct ligation (CBDL) responded uniformly to atrial natriuretic peptide (ANF) by infusing this peptide sequentially over 8–12 weeks at 175 ng∙kg−1∙min−1 and observing the natriuretic response. ANF was administered every 2 weeks post-CBDL until the 8th week and given again during the cirrhotic phase with ascites present (10–12 weeks post-CBDL). Sodium balance studies were conducted at similar time intervals. During the control period and at weeks, 2, 6, and 8 post-CBDL all dogs responded to ANF with a significant change in sodium excretion (ΔUNaV, 50–240 μequiv./min). At these times, all dogs were in sodium balance. At week 4 and during the ascitic period, heterogeneity of response to ANF was observed. In the former interval, five dogs responded (ΔUNaV, 75–230 μequiv./min) and four did not, while in the latter interval, five dogs responded (ΔUNaV, 50–240 μequiv./min) and three did not (one dog died). In both time periods, there was severe urinary sodium retention (daily UNaV, 11 ± 3 and 2 ± 1 mequiv./day, respectively) while the dogs were ingesting 45 mequiv. Na+/day. The heterogeneity of natriuretic response was not correlated to plasma immunoreactive ANF, renin, or aldosterone levels. Plasma volume was significantly expanded from control during both intervals. We conclude that there is transient sodium retention during the 4th week post-CBDL, and that this period is associated with the heterogeneity of natriuretic response to ANF, despite the absence of ascites or edema.Key words: sodium excretion, cirrhosis, edema.
Impact of increased infarct transmurality on remodeling and function during healing after anterior myocardial infarction in the dog
Authors: Jugdutt Bodh I. , Khan Mohammad I.
Published: April 2011

To determine the impact of greater infarct transmurality on changes in left ventricular remodeling and function after acute anterior myocardial infarction, serial topographic and functional parameters (two-dimensional echocardiograms) and hemodynamics over 6 weeks, and postmortem topography (planimetry) at 6 weeks, were measured in chronically instrumented dogs randomized to standard coronary artery ligation (group 1) or a modified lower ligation plus collateral obliteration to decrease collateral inflow and increase transmurality (group 2). At 6 weeks, postmortem scar size and collagen were similar in the two groups, but group 2 had greater transmurality associated with more necrosis relative to area at risk, Q waves, infarct expansion, thinning, regional bulging, and cavity dilatation. Over the 6 weeks, group 2 showed more early expansion, late thinning and regional bulging in the short axis, larger diastolic and systolic volumes, and more apical aneurysmal bulging in the long-axis, reflecting more topographic deterioration. More important, group 2 showed greater regional and global left ventricular dysfunction over 6 weeks, lower ejection fraction at 2 days with further decrease over 6 weeks, and more left ventricular thrombus, ventricular arrhythmias, and deaths. In addition, transmurality correlated with the severity of remodeling and dysfunction. The findings indicate that transmurality is a major determinant of remodeling and left ventricular dysfunction during healing after anterior infarction.Key words: infarct expansion, echocardiography, aneurysm, Q wave infarction.
The TCA cycle as an oxidative and synthetic pathway is suppressed with aging in jejunal epithelial cells
Authors: Fleming S. E. , Kight C. E.
Published: April 2011

The influence of aging on glucose and glutamine metabolism by isolated jejunal cells was studied using young (4 months) and aged (24 months) Fischer 344 male rats when fed ad libitum or fasted 48 h. Concentration-dependent oxidation of glucose ([14C(U)]glucose) followed Michaelis–Menten kinetics. Neither Kox nor Vmax was influenced by animal age or feeding status, but at 1 mM, glucose oxidation was significantly higher for aged than young fed animals. In all animal groups, glutamine reduced glucose oxidation by ca. 60%, glucose stimulated glutamine oxidation by ca. 25%, and succinate CO2 ratios ranged from 1.37 for 20 mM glucose to 5.46 for 20 mM glucose + glutamine. The probability that a substrate that enters the TCA cycle will either remain in the cycle for one complete turn or leave and reenter as acetyl-CoA averaged 0.85 for glucose, 0.36 for glutamine, and 0.31 for glucose + glutamine. In comparison with the young fed animals, cells from fed aged animals showed lower oxygen uptake in the absence and presence of exogenous substrate, lower glucose oxidation, lower entry of glucose and glutamine into the TCA cycle, and lower contribution of glucose and glutamine carbon to anaplerosis and subsequent synthetic compounds. Differences between the young and aged animals were more pronounced in cells from fed animals than from fasted animals.Key words: glucose, glutamine, fasting, oxidation, anaplerosis.
Distensibility of portacaval shunts in portal hypertensive cats: index of contractility model
Authors: Inglés Andrés C. , Legare Dallas J. , Lautt W. Wayne
Published: April 2011

Complete shunting of portal blood flow through portacaval shunts was obtained using a constrictor around the portal vein to gradually produce a total occlusion. After 4 weeks, acute experiments were conducted in anesthetized cats. Blood from the femoral artery was shunted through a pump to supply and control the entire portal blood flow. As shunted portal blood flow was varied over a wide range, the portal shunt resistance showed distensibility. Decreasing portal venous pressure from 15.0 ± 0.9 to 11.1 ± 0.6 mmHg (1 mmHg = 133.3 Pa) resulted in elevations of resistance of 58%. The relation between the resistance (R) and the distending pressure (Pd) was a constant, the index of contractility (IC), where IC = R∙Pd3. In steady state, the IC was 485 ± 55 mmHg4∙mL−1∙min∙kg and did not change passively in response to changes in portal blood flow. In conclusion, portacaval shunts are passively distensible, and resistance is altered as a cubic function of the distending pressure. Because resistance is altered both actively and passively, the IC should prove useful to differentiate these alternatives for evaluation of changes in portal hypertensive therapy.Key words: portacaval shunts, distensibility model, vascular resistance, index of contractility.
Hemorrhage from the inferior vena cava versus the ear artery: a comparison of cardiovascular and hormonal responses in conscious rabbits
Authors: Woods B. A. , Myckatyn T. M. , Courneya C. A.
Published: April 2011

There are inherent complications associated with chronic indwelling venous catheters for use as bleed catheters in long term hemorrhage experiments in conscious animals. As an alternative we have developed a protocol for bleeding conscious rabbits using a disposable catheter in the central ear artery. Previously we had bled rabbits through a catheter chronically implanted in the inferior vena cava (IVC); thus, we were interested in any potential differences in the hormonal (vasopressin and renin) and cardiovascular profile during hemorrhage between the IVC and ear artery bleeds. Rabbits underwent two bleeds, 1 week apart, one using the indwelling IVC catheter and the other with an ear artery (EA) catheter. We compared the mean arterial pressure (MAP), heart rate (HR), plasma vasopressin (AVP), and plasma renin activity (PRA) before and during hemorrhage. Baseline cardiovascular and hormonal values were the same, regardless of choice of bleed site. In addition there were no differences between bleed sites in me rate of fall of MAP (slope: IVC, 0.24 ± 0.05; EA, 0.26 ± 0.04) and the rate of rise of HR (slope: IVC, −1.37 ± 0.22; EA, −1.20 ± 0.19). Finally the AVP and PRA values associated with a MAP of 50 mmHg (1 mmHg = 133.3 Pa) (close to peak levels achieved during the hemorrhage) were also not different between IVC and EA bleeds. Given that the profiles of the bleeds were not different and that surgical implantation, possible infection, and daily flushing were avoided by the use of the EA catheter, we concluded that use of the EA as a site for bleeding conscious rabbits was justified.Key words: hemorrhage, arginine vasopressin, baroreceptors, conscious rabbits.
β-Adrenergic receptor desensitization in the early stage of hereditary cardiomyopathy in hamsters
Authors: St-Onge Stéphane , Chidiac Peter , Brakier-Gingras Léa , Bouvier Michel
Published: April 2011

The β-adrenergic receptor (βAR)/adenylyl cyclase signalling pathway was examined in cardiac membranes from cardiomyopathic Syrian hamsters. Three stages were examined during the progression of this hereditary cardiomyopathy (30 days old, prenecrotic phase; 60 days old, necrotic phase; and 120 days old, compensatory phase). Isoproterenol-stimulated adenylyl cyclase activity was decreased by 32 ± 16% in 30-day-old cardiomyopathy hamsters, compared with age-matched controls. This was not accompanied by any change in the fluoride- or forskolin-stimulated activities, suggesting that the decrease reflects a perturbation of the receptor-mediated stimulation. Neither the density nor the subcellular distribution of the βAR, as assessed by [125I]iodocyanopindolol binding assays, was affected in these animals. However, the agonist binding properties of the βAR were significantly affected. Indeed, the effect of guanyl nucleotides on isoproterenol binding was decreased in 30-day-old cardiomyopathic hamsters. Given that guanyl nucleotide sensitivity is correlated with the ability of the βAR to productively interact with Gs protein, these results suggest that the decreased β-adrenergic-stimulated adenylyl cyclase activity results from a functional uncoupling of the βAR with no change in receptor density. The desensitization of the β-adrenergic-stimulated adenylyl cyclase was transient, since no change in isoproterenol-stimulated adenylyl cyclase was detected in 60- and 120-day-old hamsters, compared with age-matched controls. Similarly, the receptor number and distribution were not affected at those ages. The desensitization in the βAR/adenylyl cyclase signalling pathway, occurring early in the development of the pathology, may result from the increased sympathetic tone associated with this pathology and may be part of the sequence of events leading to the progression of the cardiomyopathy in hamsters.Key words: β-adrenergic receptor, desensitization, cardiomyopathic hamsters.
Cellular blood constituents and serum protein fractions of the chinchilla (Chinchilla lanigera)
Authors: Kitts W. D. , Krishnamurti C. R. , Hudson R. J.
Published: April 2011

The hematology and serum proteins of the chinchilla are described. Mean values obtained for hematologic parameters were erythrocyte count, 7.2 × 106/cmm; leukocyte count, 8.7 × 103/cmm; hematocrit, 41.9%; and hemoglobin, 14.7 g/100 ml. Differential counts revealed a large proportion of lymphocytes (65.7%). No significant effect of age on these blood constituents was detected. Disc electrophoresis of chinchilla serum proteins disclosed at least 13 distinct bands. Chemical fractionation using ethacridine lactate, gel filtration, and anion exchange chromatography was used to identify several of the proteins. The ratio of the concentration of transferrin to albumin was elevated in blood samples collected during March and April. This was suggested to be related either to pregnancy or to hair growth. Significant individual variation was detected in the levels of albumin and globulin and the ratio of these two fractions. Individual effects for globulin and the albumin–globulin ratio appeared to be related to the age of the animals.
Photoperiodic activity changes in juvenile sockeye salmon (Oncorhynchus nerka)
Authors: Byrne John E.
Published: April 2011

Spontaneous locomotor activity was studied in juvenile sockeye salmon under controlled environmental conditions (LD 9.5:14.5 or 12:12; 5 °C; 0.1–34.4 lux). Siblings were hatched in activity chambers and swimming movements were monitored with an ultrasonic system for 11 months. The experiments gave evidence of a bimodal activity rhythm in sockeye fry immediately after hatching. The bimodal, dark-active pattern persisted until 9 days after the fish emerged from the gravel. The photobehavioral response was reversed and the fish expressed a unimodal, light-active pattern 10–14 days after first emergence. This light-active response was then maintained for 11 months.The possible interrelationships between age, photobehavioral response, and activity rhythms underlying the sockeye fry migrations to nursery lakes are discussed.
THE ORBIFOLD-STRING THEORIES OF PERMUTATION-TYPE III: LORENTZIAN AND EUCLIDEAN SPACE—TIMES IN A LARGE EXAMPLE
Authors: HALPERN M. B.
Published: April 2011

To illustrate the general results of the previous paper, we discuss here a large concrete example of the orbifold-string theories of permutation-type. For each of the many subexamples, we focus on evaluation of the target space–time dimension[Formula: see text], the target space–time signature and the target space–time symmetry of each cycle j in each twisted sector σ. We find in particular a gratifying space–time symmetry enhancement which naturally matches the space–time symmetry of each cycle to its space–time dimension. Although the orbifolds of ℤ2-permutation-type are naturally Lorentzian, we find that the target space–times associated with larger permutation groups can be Lorentzian, Euclidean and even null [Formula: see text], with varying space–time dimensions, signature and symmetry in a single orbifold.
QUANTIZATION OF HIGHER-DIMENSIONAL LINEAR DILATON BLACK HOLE AREA/ENTROPY FROM QUASINORMAL MODES
Authors: SAKALLI I.
Published: April 2011

The quantum spectra of area and entropy of higher-dimensional linear dilaton black holes in various theories via the quasinormal modes method are studied. It is shown that quasinormal modes of these black holes can reveal themselves when a specific condition holds. Finally, we obtain that a higher-dimensional linear dilaton black hole has equidistant area and entropy spectra, and both of them are independent on the space–time dimension.
EXTREMAL BLACK HOLES, HOLOGRAPHY AND COARSE GRAINING
Authors: SIMON JOAN
Published: April 2011

I review some of the concepts at the crossroads of gravitational thermodynamics, holography and quantum mechanics. First, the origin of gravitational thermodynamics due to coarse graining of quantum information is exemplified using the half-BPS sector of [Formula: see text] SYM and its LLM description in type IIB supergravity. The notion of black holes as effective geometries, its relation to the fuzzball programme and some of the puzzles raising for large black holes are discussed. Second, I review recent progress for extremal black holes, both microscopically, discussing a constituent model for stationary extremal non-BPS black holes, and semiclassically, discussing the extremal black hole/CFT conjecture. The latter is examined from the AdS3/CFT2 perspective. Third, I review the importance of the holographic principle to encode nonlocal gravity features allowing us to relate the gravitational physics of local observers with thermodynamics and the role causality plays in these arguments by identifying horizons (screens) as diathermic walls. I speculate with the emergence of an approximate CFT in the deep IR close to any horizon and its relation with an effective dynamical description of the degrees of freedom living on these holographic screens.
AN EMPIRICAL STUDY OF POTENTIAL-BASED REWARD SHAPING AND ADVICE IN COMPLEX, MULTI-AGENT SYSTEMS
Authors: DEVLIN SAM , KUDENKO DANIEL , GRZEŚ MAREK
Published: April 2011

This paper investigates the impact of reward shaping in multi-agent reinforcement learning as a way to incorporate domain knowledge about good strategies. In theory, potential-based reward shaping does not alter the Nash Equilibria of a stochastic game, only the exploration of the shaped agent. We demonstrate empirically the performance of reward shaping in two problem domains within the context of RoboCup KeepAway by designing three reward shaping schemes, encouraging specific behaviour such as keeping a minimum distance from other players on the same team and taking on specific roles. The results illustrate that reward shaping with multiple, simultaneous learning agents can reduce the time needed to learn a suitable policy and can alter the final group performance.
ADAPTIVE FUSION METHOD FOR USER-BASED AND ITEM-BASED COLLABORATIVE FILTERING
Authors: YAMASHITA AKIHIRO , KAWAMURA HIDENORI , SUZUKI KEIJI
Published: April 2011

In many e-commerce sites, recommender systems, which provide personalized recommendations from among a large number of items, have recently been introduced. Collaborative filtering is one of the most successful algorithms which provide recommendations using ratings of users on items. There are two approaches: user-based and item-based collaborative filtering. Additionally a unifying method for user-based and item-based collaborative filtering was proposed to improve the recommendation accuracy. The unifying approach uses a constant value as a weight parameter to unify both algorithms. However, because the optimal weight for unifying is actually different depending on the situation, the algorithm should estimate an appropriate weight dynamically, and should use it. In this research, we first investigate the relationship between recommendation accuracy and the weight parameter. The results show that the optimal weight is different depending on the situation. Second, we propose an approach for estimation of the appropriate weight value based on collected ratings. Then, we discuss the effectiveness of the proposed approach based on both multi-agent simulation and the MovieLens dataset. The results show that the proposed approach can estimate the weight value within an error rate of 0.5% for the optimal weight.
ALGEBRAIC STRUCTURES OF MULTIPARTITE QUANTUM SYSTEMS
Authors: HEYDARI HOSHANG
Published: April 2011

We investigate the relation between multilinear mappings and multipartite states. We show that the isomorphism between multilinear mapping and tensor product completely characterizes decomposable multipartite states in a mathematically well-defined manner.
REMOTE PREPARATION OF TWO-QUBIT ENTANGLED STATE VIA ONE-DIMENSIONAL FOUR-QUBIT CLUSTER AND CLUSTER-CLASS STATES
Authors: HAN LIAN-FANG , YUAN HAO
Published: April 2011

We propose two protocols for remotely preparing a two-qubit entangled state, where the quantum channels take the form of one-dimensional four-qubit cluster and cluster-class states, respectively. The total success probability and classical communication cost are also calculated.
INFINITE DIMENSION MODELING OF A NOVEL MICROFORCE SENSOR AND THE APPLICATION IN MICROMANIPULATION
Authors: LIU YIYANG , WANG YUECHAO , YU PENG , DONG ZAILI
Published: April 2011

To accurately measure the micro-interactive force (for example, adhesion, surface tension, friction, and assembly force) acting on microdevices during micro/nano manipulation, a novel microforce sensor that can reliably measure force in the range of sub-micro-Newton (μN) is designed and developed in this study. During the application of this microforce sensor in micro/nano manipulation, the accuracy of this sensor's model is quite important to the force control of the system. Therefore, the accurate infinite dimension model of the microforce sensor and micromanipulator is built up. Based on the infinite dimension model, the impedance control system is designed. To verify the infinite dimension model and the control system, micromanipulation experiments are designed and realized. Experiment results verify the accuracy of the infinite dimension model of the sensor and show the efficiency of the impedance control system. The developed microforce sensor and the infinite dimension modeling provide a feasible and versatile solution in microforce sensing and feedback force control for micro/nano manipulation, and will promote the technology of automating the micro/nano manipulation.
Separation of Thin GaN from Sapphire by Laser Lift-Off Technique
Authors: Ueda Tetsuzo , Ishida Masahiro , Yuri Masaaki
Published: April 2011

Laser lift-off of GaN from sapphire substrates has become a viable technique to increase the brightness of GaN-based light-emitting diodes (LEDs). The LEDs free from sapphire exhibit high luminous efficiency by placing highly reflective electrode on the back side. The devices serve low series resistance together with low thermal resistance taking advantages of the vertical structure. Thinner epitaxial structure is desired to serve better device performance, however, cracks in the film after the lift-off limits the minimum thickness. In this paper, successful laser lift-off of very thin GaN with the thickness down to 4 µm is described. The established laser lift-off system utilizes homogenized beam-profile of the employed neodymium-doped yttrium aluminium garnet (Nd:YAG) third harmonic laser in which optimization of the laser fluence minimizes the thickness of the decomposed GaN. It is also revealed by calculation that the compressive stress in the thin GaN is increased by reducing the thickness. It is demonstrated that the lattice of the GaN is relaxed after the laser lift-off, which is confirmed by photoluminescence (PL) and X-ray diffraction (XRD) measurements. In addition, reduction of the wafer bowing of GaN on sapphire is experimentally confirmed after the laser irradiation with the formation of metal Ga in between the interface.
Leakage Current Reduction Mechanism of Oxide–Nitride–Oxide Inter-Poly Dielectrics through the Post Plasma Oxidation Treatment
Authors: Lee Woong , Jee Jeonggeun , Yoo Dae-Han , Lee Eun-Young , Bok Jinkwon , Hyung Younwoo , Kim Seoksik , Kang Chang-Jin , Moon Joo-Tae , Roh Yonghan
Published: April 2011

High quality oxide–nitride–oxide (ONO) inter-poly dielectrics were successfully fabricated by the optimized plasma oxidation without H2. The bottom low pressure chemical vapor deposition (LPCVD) oxides treated by the conventional N2O annealing step were subjected to the post deposition process using a plasma treatment. This process reduces both the leakage current and the stress-induced leakage current (SILC), while no thickness increase of the bottom LPCVD oxides was observed due to the plasma treatment. Based on the photo electron injection technique, it is found that the O2 plasma oxidation method significantly reduces the defect centers located at 1.67 nm away from the bottom oxide/floating gate interface.
Improvement of Piezoelectric Properties of (K,Na)NbO3 Films Deposited by Sputtering
Authors: Shibata Kenji , Suenaga Kazufumi , Watanabe Kazutoshi , Horikiri Fumimasa , Nomoto Akira , Mishima Tomoyoshi
Published: April 2011

(K,Na)NbO3 (KNN) films with high transverse piezoelectric coefficients were successfully deposited onto Pt/Ti/SiO2/Si substrates by RF magnetron sputtering. These films were polycrystalline and had pseudo-cubic perovskite structures with preferential <001 > orientation. To improve their piezoelectric properties, we investigated the effects of annealing after the deposition and the Na/(K+ Na) ratio of the films. Annealing in air at 750 °C led to a decrease in the residual strain in the KNN crystal and the disappearance of openings at the grain boundary, thereby improving the transverse piezoelectric coefficient and leakage current properties. We also investigated the transverse piezoelectric coefficient and dielectric constant as a function of the Na/(K+ Na) ratio; both had maximum values at a ratio of approximately 0.55. For the KNN films, e
31
* ranged between -10.0 and -14.4 C/m2; thus, it was superior to previously reported values for lead-free piezoelectric films and was comparable to the best commercially available Pb(Zr,Ti)O3 films.
Proposal of Micro-Trichroic Structures for High-Sensitivity Color Image Sensors
Authors: Suzuki Yuta , Ozeki Yasuyuki , Yoshino Tomoki , Yamada Kazuhiro , Yamagata Michihiro , Tanaka Yasuhiro , Itoh Kazuyoshi
Published: April 2011

We propose a micro-trichroic structure based on multiplexed Bragg reflectors. Employing such a structure on each image sensor (IS) cell can enhance the ability of color ISs. Numerical calculations confirm the feasibility of the proposed structure. We also emulated a structure with several layers, and reduced the number of layers substantially by decreasing the diffraction angles.
Phase-Change Kinetics of Bi–Fe–(N) Layer for High-Speed Write-Once Optical Recording
Authors: Huang Sung-Hsiu , Huang Yu-Jen , Mai Hung-Chuan , Hsieh Tsung-Eong
Published: April 2011

In this work, we present the phase-change kinetics of Bi–Fe–(N) layers for write-once optical recording.In situreflectivity measurement indicated that the phase-change temperature (Tx) of the Bi–Fe–(N) layers is strongly related to the heating rate. TheTx's were about 170 °C at low heating rates and approached the melting point of the Bi phase (i.e., 271.4 °C) at high rate of heating provided by laser heating. For a 100-nm-thick Bi–Fe–(N) layer, Kissinger's analysis showed that the activation energy of phase transition (Ea) = 1.24 eV, while the analysis of isothermal phase transition in terms of the Johnson–Mehl–Avrami (JMA) theory showed that the average Avrami exponent (m) = 2.2 and the appropriate activation energy (ΔH) = 5.15 eV. With the aid of X-ray diffraction (XRD) analysis, a two-dimensional phase transition behavior in the Bi–Fe–(N) layers initiated by the melting of the Bi-rich phase was confirmed. For optical disk samples with optimized disk structure and write strategy, the signal properties far exceeding the write-once disk test specifications were achieved. Satisfactory signal properties indicated that the Bi–Fe–(N) system is a promising alternative for high-speed write-once recording in the Blu-ray era.
A High-Retardation Polymer Film for Viewing Liquid Crystal Displays through Polarized Sunglasses without Chromaticity Change in the Image
Authors: Kobayashi Daisuke , Tagaya Akihiro , Koike Yasuhiro
Published: April 2011

We describe a high-retardation polymer film (HRPF) that enables liquid crystal displays (LCDs) to be viewed through polarized sunglasses at all rotation angles without any chromaticity changes in the image. We investigated the relationship between retardation and polymer interference color after developing a program that simulates the interference colors of polymers taking into consideration the polymer birefringence dispersion and LCD emission light spectrum. As a result, we confirmed that the retardation value required for our HRPF made of polyethylene terephthalate and applied to an LCD with white LED backlight was not less than 7832 nm. We also confirmed that the image quality was not degraded by attaching the HRPF to the LCD, and chromaticity change in the image observed through HRPF and polarized sunglasses was negligible compared to the LCD image.
Evaluation of Yields of γ-Rays Produced by Electrons from Gas Jets Irradiated by Low-Energy Laser Pulses: Towards “Virtual Radioisotopes”
Authors: Oishi Yuji , Nayuki Takuya , Zhidkov Alexei , Fujii Takashi , Nemoto Koshichi
Published: April 2011

Electron generation from a gas jet irradiated by low-energy femtosecond laser pulses is studied as a promising source of ∼1 MeV radiation for radioisotope-free γ-ray imaging systems: “virtual radioisotopes”. The yield of γ-rays in the 0.5–2 MeV range produced by low-average-power lasers and gas targets exceeds the yields from solid tape targets up to 2 orders of magnitude; it can be competitive with the yield from conventional radioisotopes used in industrial applications.
Anchoring Au and Pt Nanoparticles on Multiwalled Carbon Nanotubes via Electron Beam Induced Amorphous Carbon Encapsulation
Authors: Song Wooseok , Kim Sung Hwan , Kim Yooseok , Kim Soo Youn , Jeon Cheolho , Choi Won Chel , Lee Byung Cheol , Park Chong-Yun
Published: April 2011

Au and Pt nanoparticles (NPs) were anchored on multiwalled carbon nanotubes (MWCNTs) via electron beam induced amorphous carbon encapsulation by energy-tunable MeV electron beam irradiation (MEBI) under ambient conditions. MEBI allowed the formation of size-homogeneous Au and Pt NPs on MWCNTs, as observed by transmission electron microscopy. Anchoring of metal NPs was achieved by MEBI-induced amorphous carbon encapsulation. The chemical doping effects of Au and Pt NPs were also verified by Raman spectroscopy. MEBI may provide a facile methodology for anchoring metal NPs to enhance electrical conductivity without destruction of MWCNTs.
Electronic and Optical Properties of Indium Zinc Oxide Thin Films Prepared by Using Nanopowder Target
Authors: Kim Hwa-Min , Bae Kang , Sohn Sunyoung
Published: April 2011

Indium zinc oxide (IZO) films were deposited on glass substrates using the rf-magnetron sputtering method and a powder target made up of nanoparticles with a size less than 100 nm. In this study, the optical, structural, and electrical properties of the IZO films deposited using a nanopowder target compared with those of the IZO films deposited using a micropowder target made up of microparticles with a size greater than 30 µm were examined. The IZO films deposited using nanopowder at room temperature were amorphous and showed a low resistivity of 4.5 ×10-4 Ω·cm and a high transmittance over an average of 85% in the visible range, indicating that these films showed more enhanced properties than the IZO film deposited using micropowder. The enhanced properties of the IZO film prepared with nanopowder were considered to be caused by the marked improvement in packing density with increases in refractive index and surface roughness from atomic force microscopy (AFM) images due to the powder target consisting of nanoparticles.
Self-Assembled Nano-heterostructural Thin Film for Optical Lens
Authors: Fujimoto Kouji , Kyung Kyu-Hong , Shiratori Seimei
Published: April 2011

The layer-by-layer (LBL) self-assembly method enables the deposition of functional nanoscale multilayer thin films on intricate-shape substrates. The present problem with optical devices is the formation of a uniform coating of a nanoscale heterostructural thin film on both faces of the lens. In this paper, we introduce self-assembled heterostructural optical films with higher- and lower-refractive index layers, which were fabricated using a stable water base titanium complex [titanium(IV) bis(ammonium lactato) dihydroxide (TALH)] and cationic and anionic polyelectrolytes [poly(diallyldimethylammonium chloride) (PDDA)] and [poly(acrylic acid) (PAA)] on a lens via the LBL method. The antireflectance characteristics of (PDDA/TALH)20/(PDDA/PAA)20showed a maximum transmittance of 99.2% with (PDDA/TALH)20(ca.1.75, 80 nm) and (PDDA/PAA)20(ca.1.48, 87 nm) on both faces of the lens. These results demonstrate that we can control the refractive index and film thickness of self-assembled nano-heterostructural films on optical lenses.
Effect of Heat Treatment on Ion Conductivity of Hydrated ZrO2 Thin Films Prepared by Reactive Sputtering Using H2O Gas
Authors: Li Ning , Abe Yoshio , Kawamura Midori , Sasaki Katsutaka , Itoh Hidenobu , Suzuki Tsutomu
Published: April 2011

Hydrated ZrO2 thin films were prepared by reactive sputtering using H2O gas, and these films were heat treated in air at temperatures from 100 to 350 °C. Absorbance peaks due to hydrogen-bonded OH groups for these samples were observed by Fourier transform infrared spectroscopy. The peak intensities were nearly the same before and after heat treatment below 200 °C, but began to decrease at 250 °C, and the absorption peak disappeared at 350 °C. Ion conductivity of the films was evaluated by AC impedance measurements and was found to be about 3 ×10-6 S/m before and after heat treatment at 200 °C; it also decreased after heat treatment above 250 °C. From these results, we considered that protons of OH and/or H2O in the films are the dominant ionic species that contribute to the ion conductivity of the films.
Electromagnetic Imprint Technique Combined with Electrophoretic Deposition Technique in Forming Microelectrode Structures
Authors: Weng Yung Chun , Weng Yung Jin , Fang Huang Sheng , Yang Sen Yeu
Published: April 2011

In this study, we integrate the electromagnetic soft mold imprint technique with the electrophoretic deposition technique, and apply them to forming microelectrode structures. The compound casting technology is used to produce a magnetic soft mold of a microelectrode structure, which can effectively reduce the time and cost of molding. The use of an electromagnetic imprint device can apply more evenly distributed imprint pressure, thus, the microelectrode structure can be entirely imprinted onto an indium tin oxide (ITO) soft substrate, and then the electrophoretic deposition technique is employed to deposit titanium dioxide (TiO2) nanopowder on the ITO soft substrate of the microelectrode structure. In addition to the key techniques and processes of electromagnetic soft mold imprinting, In this study, we explore the application of electrophoretic deposition and imprinting to prove that combining these techniques to form a microelectrode structure is a simple, low-cost, high duplication, and high-speed process. It is proven a good choice for producing micro-nanocomponents.
A New Technique for Enhancing Sensitivity of the 2ω Method by Applying a Bismuth Film Thermoreflectance Sensor on Top of the Metal Film–Dielectric Substrate Sample
Authors: Kato Ryozo , Xu Yibin , Goto Masahiro
Published: April 2011

In this paper, a new technique for enhancing the sensitivity of the 2ω method is discussed. In the conventional 2ω method, the metal film is periodically Joule-heated and the ac temperature response at the surface of the metal film is measured by thermoreflectance to determine the thermal resistance of a thin film deposited on a dielectric substrate and also the interfacial thermal resistance between the layers. The problem with the conventional 2ω method is that it is very hard to obtain good sensitivity of the ac temperature measurement owing to the very low thermoreflectance coefficient of the metals. The sensitivity can be enhanced by just applying a Bi film thermoreflectance sensor on top of the metal film–dielectric substrate sample. However, the applied Bi film produces another thermal resistance and also interfacial thermal resistance between the Bi film layer and the metal film layer, which might affect the result of the measurement. Then we tried to solve the thermal conduction equation of the thermal system. In this case, only the metal film layer is Joule-heated and the ac temperature response at the surface of the Bi film layer is measured by thermoreflectance. Thus, we obtained exactly the same approximate equation as that of the thermal system for the metal film–dielectric substrate sample, showing that the thermal resistance of the Bi film and also the interfacial thermal resistance between the Bi film and the metal film are unobservable. We successfully determined the interfacial thermal resistance between the Au film and the Al2O3 substrate with much improved precision compared with the conventional 2ω method by measuring the Bi film–Au film–Al2O3 substrate sample.
Analysis of High-Intensity Focused Ultrasound Source Using Time Reversal: Effect of Lamb-Like Waves
Authors: Kaneshima Yasuhiro , Yoshizawa Shin , Umemura Shin-ichiro
Published: April 2011

The pressure distribution of a focused ultrasound source was reconstructed from a measured pressure field on the focal plane using time-reversal. The two-dimensional Fourier transform of the distribution in the time and space domain showed a peak with a finite phase velocity, which corresponds to a mode of waves propagating from the circumference to the center of the transducer similar to Lamb waves. It was numerically confirmed that the propagating waves significantly enhanced the secondary lobe on the near side of the main focal lobe. The near side lobe was markedly reduced by increasing the thickness of the transducer by three times in the experiment. This significant change is consistent with the hypothesis that the near side lobe was formed by Lamb-like waves.
Nonconfocal Differential Interferometry Sensing Scheme for Scanning Probe Microscopy
Authors: Lin Yu-Cheng , Cheng Stone
Published: April 2011

In this work, we describe a nonconfocal differential interferometer to detect the cantilever vibration for a scanning probe microscope. Capable of focusing the beams on the different height surfaces of a cantilever to adapt the length of commercially available cantilever chips, the proposed two-beam interferometer can maintain the sensitivity by placing a glass slip for an object beam to extend the focal length to the cantilever. An experiment involving a scanning force microscope is performed in static mode operation for applications where topography and magnetic images are presented.
Measurement of Lithium Diffusion Coefficient in Li
y
FeSO4F
Authors: Delacourt C. , Ati M. , Tarascon J. M.
Published: April 2011

Lithium diffusion coefficient (

D

) in Li
y
FeSO4F is investigated by means of three electrochemical techniques, namely potentiostatic intermittent titration technique (PITT), galvanostatic intermittent titration technique (GITT), and galvanostatic charge/discharge at different C-rates. The analytic equations used for analyzing PITT and GITT are based on radial diffusion in spherical particles, which is more suitable to the type of electrode studied here than the original equations derived by Wen et al. [J. Electrochem. Soc., 126, 2258 (1979).] for a slab geometry. While PITT and GITT analyses with the analytic equations are only valid in the partial solid solution regions (

y
≤
0
.
29

and

y
≥
0
.
83

in Li
y
FeSO4F), the analysis of galvanostatic charge/discharge with a mathematical model allows for the determination of

D

over the entire lithium composition range. The average

D

values found with PITT and GITT analyses are in good agreement with each other, and of the same order as those reported for Li
y
FePO4 in the literature (ca. 10−14 cm2/s); However,

D

is larger for Li
y
FeSO4F in the Li-rich composition range than in the Li-poor one, whereas it is the opposite for Li
y
FePO4. This result could explain why Li
y
FeSO4F has a better rate capability on discharge than Li
y
FePO4.
Transferring Thin Film GaN LED Epi-Structure to the Cu Substrate by Chemical Lift-Off Technology
Authors: Horng Ray-Hua , Pan Chun-Ting , Tsai Tsung-Yen , Wuu Dong-Sing
Published: April 2011

In this paper, a patterned sacrificial layer structure comprised of 3 μm-wide SiO2 narrow strips and 3 μm spacing between strips fabricated on sapphire substrate was proposed. The structure was used not only to improve GaN epilayer quality, but also as a sacrificial layer structure. The GaN light emitting diodes (LEDs) covered by the Cu substrate was fabricated after the GaN epitaxy layer was grown on the sapphire by lateral epitaxial overgrowth. Chemical etching using hydrofluoric acid was conducted to remove the aforementioned SiO2 strips, and hence transform them into narrow tunnels. The GaN LEDs with the Cu substrate detached from the sapphire substrate after interface strain was increased, which demonstrates that n-side-up vertical GaN LEDs could be more easily obtained using chemical lift-off technology without laser damage compared with the laser lift-off technique.
Working memory templates are maintained as feature-specific perceptual codes
Authors: Sreenivasan Kartik K. , Sambhara Deepak , Jha Amishi P.
Published: April 2011

Working memory (WM) representations serve as templates that guide behavior, but the neural basis of these templates remains elusive. We tested the hypothesis that WM templates are maintained by biasing activity in sensoriperceptual neurons that code for features of items being held in memory. Neural activity was recorded using event-related potentials (ERPs) as participants viewed a series of faces and responded when a face matched a target face held in WM. Our prediction was that if activity in neurons coding for the features of the target is preferentially weighted during maintenance of the target, then ERP activity evoked by a nontarget probe face should be commensurate with the visual similarity between target and probe. Visual similarity was operationalized as the degree of overlap in visual features between target and probe. A face-sensitive ERP response was modulated by target-probe similarity. Amplitude was largest for probes that were similar to the target, and decreased monotonically as a function of decreasing target-probe similarity. These results indicate that neural activity is weighted in favor of visual features that comprise an actively held memory representation. As such, our findings support the notion that WM templates rely on neural populations involved in forming percepts of memory items.