bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro culture and mtDNA fate of ibex–rabbit nuclear transfer embryos
Authors: Jiang Yan , Chen Tao , Nan Chang-Long , Ouyang Ying-Chun , Sun Qing-Yuan , Chen Da-Yuan
Published: September 2005

Rabbit oocyte can be used as the recipient in interspecies somatic cell nuclear transfer (iSCNT). This work was undertaken in order to study the developmental competence of Capra ibex somatic cells reprogrammed by rabbit oocytes and the fate of mitochondria in iSCNT embryos. Metaphase II (MII) oocytes from superovulated rabbit were used as nuclear recipients. The nuclear donors were Capra ibex somatic cells with different proliferative status: population doubling time (PDL)=15±2 (group 1), 35±2 (group 2), 55±2 (group 3) and 70±2 (group 4). Oocytes reconstructed with electrical pulses (2.1 kV/cm, 10 μs, 2 times) were activated (1.4 kV, 20 μs, 2 times) and then cultured in Medium199 containing 10% fetal bovine serum at 38.5 °C, 5% CO2 in air. In groups 1, 2, 3 and 4, the fusion rates were 35.83%, 66.03%, 65.40% and 35.35%, respectively. Similar cleavage rates were observed among the four groups. However, the developmental potential to morula/blastocyst from early nuclear donor embryos (16.42%/10.45%) was significantly higher (p < 0.05) than in terminal donor embryos (9.52%/3.81%). Polymerase chain reaction analysis of the mitochondrial (mt) DNA cytb gene demonstrated that mtDNAs from ibex and rabbit could be detected at various developmental stages before implantation. In conclusion, our results provide some original information about rescuing Capra ibex using the iSCNT technique. These results indicate that: (1) enucleated rabbit oocytes make Capra ibex fibroblast nuclei reprogramme; (2) the proliferative status of donor cells affects the efficiency of iSCNT; and (3) rabbit ooplasm rescues the donor-derived mtDNAs, resulting in mtDNA heteroplasmy before implantation.
Hyaluronan and its binding proteins in the epithelium and intraluminal fluid of the bovine oviduct
Authors: Bergqvist Ann-Sofi , Yokoo Masaki , Heldin Paraskevi , Frendin Jan , Sato Eimei , Rodríguez-Martínez Heriberto
Published: September 2005

Hyaluronan (HA) is involved in several important steps of sperm storage and of fertilization. This study investigates the presence and concentration of HA in oviductal fluid (ODF), together with the localization of HA and the presence of hyaluronan-binding proteins (HABPs) in the oviductal epithelium of normally cycling dairy heifers and cows. The concentration and amount of HA in ODF, collected over the course of several oestrous cycles via catheters placed in the isthmic and ampullar tubal segments, were measured using an ELISA. The concentration and amount of HA in ODF did not vary significantly between these anatomical regions, nor between the stages of the oestrous cycle (p>0.05), although the amount of HA seemed to peak during oestrous. The most HA per day (2.9±0.64μg, least square mean±SEM) was produced on the day of ovulation, whereas the lowest amount (1.25±0.68μg) was produced 4 days before ovulation. To investigate the localization of HA, tissue samples were retrieved at well-defined stages of the oestrous cycle and from corresponding regions of the oviduct. Sections and protein extracts from the tissue samples were studied histochemically using biotinylated HABP and immunoblotted with fluorescein isothiocyanate (FITC)-HA, respectively. Presence of HA labelling in the oviductal epithelium was restricted to the sperm reservoir, a localization that seemed to be cycle-independent. The immunoblotting of samples from the lining epithelium revealed seven bands of HABPs. We confirm that the bovine oviduct produces HA and its binding proteins, and that HA is mainly localized to the epithelium of the sperm reservoir.
Septate junctions mediate the barrier to paracellular permeability in sea urchin embryos
Authors: Itza Erin M. , Mozingo Nancy M.
Published: September 2005

In sea urchin embryos, blastula formation occurs between the seventh and tenth cleavage and is associated with changes in the permeability properties of the epithelium although the structures responsible for mediating these changes are not known. Tight junctions regulate the barrier to paracellular permeability in chordate epithelia; however, the sea urchin blastula epithelium lacks tight junctions and instead possesses septate junctions. Septate junctions are unique to non-chordate invertebrate cell layers and have a characteristic ladder-like appearance whereby adjacent cells are connected by septa. To determine the function of septate junctions in sea urchin embryos, the permeability characteristics of the embryonic sea urchin epithelia were assessed. First, the developmental stage at which a barrier to paracellular permeability arises was examined and found to be in place after the eighth cleavage division. The mature blastula epithelium is impermeable to macromolecules; however, brief depletion of divalent cations renders the epithelium permeable. The ability of the blastula epithelium to recover from depletion of divalent cations and re-establish a barrier to paracellular permeability using fluorescently labelled lectins was also examined. Finally, septate junction structure was examined in embryos in which the permeability status of the epithelium was known. The results provide evidence that septate junctions mediate the barrier to paracellular permeability in sea urchin embryos.
Effects of oocyte collection time and injection position on pronucleus formation and blastocyst development in round spermatid injection in mouse
Authors: Jiang Man-Xi , Zheng Yue-Liang , Liu Shu-Zhen , Yang Cai-Xia , Zhang Li-Sheng , Ouyang Ying-Chun , Sun Qing-Yuan , Chen Da-Yuan
Published: September 2005

The injection of spermatozoa into mouse, human and rabbit oocytes at specific times and positions can result in different rates of viable embryo development. However, it is not clear how the timing and position of round spermatid injection (ROSI) affect pronucleus (PN) formation and blastocyst development of mice. First, we determined the changes in relative position of the first polar body and the spindle, carried out ROSI from 11.5 to 13 h post-hCG administration, then activated by Sr2+, and finally compared the development of ROSI zygotes, including the formation of pronuclei and development of blastocyst. Between 11.5 and 13 h post-hCG administration, the rate of 2PN formation by ROSI at 3 o'clock was the highest among all treated oocytes. Moreover, the blastocyst rate of zygotes with two pronuclei (2PN) was up to 27.41%. These results suggest that the time and position of ROSI can significantly influence the formation of 2PN, that the rates of 2PN formation are closely correlated with blastocyst formation and that the formation of 2PN is necessary for later embryo development.
Effect of exogenous carbohydrates in a serum-free culture medium on the development of in vitro matured and fertilized porcine embryos
Authors: Park Yoonee , Hong Jiyoung , Yong Hwanyul , Lim Jeongmook , Lee Eunsong
Published: September 2005

This study was conducted to examine the effect of energy substrates in a serum-free culture medium on in vitro development of porcine embryos. Presumptive zygotes derived from in vitro fertilization were cultured in glucose-free North Carolina State University (NCSU)-23 medium with glucose, pyruvate, fructose and lactate added to the culture medium singly or in various combinations. In experiment 1, a higher percentage of embryos cleaved (53–63% vs 10–13%) and developed to the blastocyst stage (18–27% vs 0) after the single addition of glucose (5.6 mM), pyruvate (0.5 mM) or lactate (10 mM) than with no energy substrate addition or the addition only of fructose (5.6 mM). In experiment 2, the addition of pyruvate and lactate resulted in higher blastocyst formation (25%) than other combinations (6–22%), while the addition of glucose and pyruvate significantly inhibited blastocyst formation. Increasing lactate concentration, as a single energy supplement, from 5 to 20 mM significantly improved blastocyst formation (7% vs 14–18%), while no benefit was achieved from increasing pyruvate concentration up to 2 mM (experiment 3). Glucose-free NCSU-23 medium supplemented with 0.5 mM pyruvate and 5 mM lactate significantly improved blastocyst formation (28% vs 17%) compared with NCSU-23 medium supplemented with 5.6 mM glucose (experiment 4). In conclusion, pyruvate and lactate are preferable energy substrates to support in vitro development of porcine embryos cultured in a serum-free NCSU-23 medium.
Regional circulation of the Monterey Bay region: Hydrostatic versus nonhydrostatic modeling
Authors: Tseng Yu‐Heng , Dietrich David E. , Ferziger Joel H.
Published: September 2005

Ocean circulation off the west coast of the United States is driven by a variety of mechanisms, the most important of which are the seasonally varying local wind stress and coastal irregularities. Remote forcing is also important and expressed through the open boundary conditions. We use a nonhydrostatic, Dietrich/Center for Air‐Sea Technology (DieCAST) ocean model to simulate the regional circulation in the vicinity of Monterey Bay, California. Satellite images often show a cyclonic eddy in the bay and an anticyclonic eddy outside the bay during spring and summer. We compare the simulation results with observed mooring and HF radar‐derived velocity data. The coastal geometry plays an important role in the generation and movement of coastal eddies. Quantitative comparisons between hydrostatic and nonhydrostatic models are made to investigate the importance of the nonhydrostatic effects in coastal ocean simulation. The results show that both the Sur Ridge area and the Monterey Submarine Canyon contribute significantly to nonhydrostatic effects and small‐scale features. The strong nonhydrostatic and small‐scale features result from the California Undercurrent flows across sloping bathymetry and interactions with near‐surface California Current in summer. Rapid changes in slope in the presence of strong flows cause vertical acceleration, which violates the hydrostatic approximation. Surface‐trapped nonhydrostatic fronts also occur frequently in the shallow ocean during winter. These effects have seasonal variation and cannot be ignored in coastal ocean modeling with complex bathymetry.
Global thermospheric neutral density and wind response to the severe 2003 geomagnetic storms from CHAMP accelerometer data
Authors: Sutton E. K. , Forbes J. M. , Nerem R. S.
Published: September 2005

Measurements of atmospheric density near 410 km from the STAR accelerometer on the CHAMP satellite are used to illustrate the spatial‐temporal dependence of the thermospheric response to the severe solar storms occurring during 29 October to 1 November 2003. This interval includes periods of elevated magnetic activity with KP values of 5–9, as well as undisturbed intervals that serve to define quiet time baseline densities. Measurements are available from −87° to +87° latitude during both day and night at local times near 1300 and 0100 hours, respectively. During times of maximum geomagnetic activity for this study, density measurements exhibit enhancements of 200–300%. Northern Hemisphere daytime responses are much larger than in the Southern Hemisphere; the origins of this effect are unknown. Nighttime density disturbances more readily propagate to equatorial latitudes, possibly facilitated by the predominant equatorward flow in both hemispheres due to the diurnal tides driven by in situ EUV heating. The CHAMP density measurements are compared with density predictions from the NRL‐MSISe00 empirical density model and demonstrate some model shortcomings. Measurements of cross‐track accelerations provide the opportunity to estimate zonal winds from the equator to about ±60° latitude, transitioning to a measure of purely meridional winds at the turning point of the orbit near ±87° latitude. A periodic variation in cross‐track winds with an apparent period of 24 hours appears at high latitudes and exhibits similar amplitudes and temporal‐latitudinal structures to the empirical HWM‐93 wind model when projected into the cross‐track direction. This periodicity is due to the displacement of geomagnetic and geographic coordinates. At low latitudes, CHAMP and HWM‐93 both yield westward winds of order 100 ms−1 during midday under quiet magnetic conditions; however, during severely disturbed periods the HWM‐93 winds generally show a greater westward intensification (to 250 ms−1) than the CHAMP measurements. At night, CHAMP winds are near zero under quiet conditions whereas HWM‐93 indicates eastward winds of order 50–100 ms−1. Under disturbed conditions the CHAMP winds shift to westward values of order 200 to 250 ms−1, while HMW‐93 values do not exceed about 50 ms−1 in the westward direction. The physical origins of the observed effects are difficult to isolate, and unequivocal interpretation will require sophisticated numerical modeling taking into account self‐consistent interactions between the neutral winds, drifts, and ionization densities.
The role of convective plumes and vortices on the global aerosol budget
Authors: Koch Jacquelin , Renno Nilton O.
Published: September 2005

Atmospheric aerosols produce both a direct radiative forcing by scattering and absorbing solar and infrared radiation, and an indirect radiative forcing by altering cloud processes. Therefore, it is essential to understand the physical processes that contribute to the global aerosol budget. The International Panel on Climate Change (IPCC) reports that mineral dust contributes to ∼1/3 of all primary particle emissions to the atmosphere. The significance of mineral dust aerosol becomes evident when one considers the large surface area of arid and semi‐arid regions on most continents. It is evident from observations in the U.S. Southwest that convective plumes and vortices lift large quantities of desert dust. Here, we use a combination of observational data and theory to determine the role of convective plumes and vortices on the global aerosol budget. We show that convective plumes and vortices contribute to about 35% of the global budget of mineral dust.
Ionospheric effects of the cosmic gamma ray burst of 29 March 2003
Authors: Maeda Koitiro , Tomizawa Ichiro , Shibata Takashi F. , Tokimasa Noritaka , Saito Akinori , Maruyama Takashi
Published: September 2005

We present evidence for ionospheric effects caused by the gamma ray burst that originated at a cosmological distance. At the time of the strong cosmic gamma‐ray burst of 29 March 2003 (GRB030329) that took place in the nighttime in Japan we observed a transient decrease in the strength of the radio noise coming from extraterrestrial sources (cosmic noise) at 38 MHz. We also observed a sudden field‐amplitude decrease of an 8.006 MHz transmission signal recorded at a distance of 690 km from the transmitter. These phenomena are interpreted as a result of an ionospheric absorption enhancement due to transient ionization caused by GRB030329. We also report no appreciable effect on the ionospheric electron column content derived using GPS (Global Positioning System) microwave signals.
EOF analysis of upper ocean heat content, 1956–2003
Authors: Levitus S. , Antonov J. I. , Boyer T. P. , Garcia H. E. , Locarnini R. A.
Published: September 2005

We present results of an EOF analyses of yearly (1956–2003), global ocean heat content fields (0–700 m layer) on a one‐degree, latitude‐longitude grid. The observed global ocean heat content integral is well‐reproduced by reconstructing this quantity using the first four EOFs. Results of an independent Fourier analysis of these same heat content fields show that the global heat content integral can be accounted for by phenomena with decadal and longer time‐scales. The temporal variability of the global integral of 0–700 m ocean heat content is due to gyre and basin‐scale spatial variability on decadal time‐scales. The strong interdecadal variability observed in the ocean heat content record is associated with the reversal of polarity of the PDO.
E × B drift simulation in an Eulerian ionospheric model using the total variation diminishing numerical scheme
Authors: Kulchitsky Anton , Maurits Sergei , Watkins Brenton , McAllister Jeffrey
Published: September 2005

The University of Alaska Fairbanks Eulerian Polar Parallel Ionospheric Model is a high‐resolution model of the polar ionosphere that incorporates multiple ion species. This paper briefly describes this model and the implementation of the total variation diminishing (TVD) advection scheme. The model is based on an Eulerian framework. It is demonstrated that the minimal numerical diffusion of the TVD advection scheme is critical for maintaining ion density gradients with high‐resolution Eulerian ionospheric models. The performance of this method is discussed and compared with an upwind numerical scheme. A sample model run for 24 October 2003 that simulates the formation of polar cap ionospheric structures is presented. The results using the TVD advection scheme are compared with the corner transport upwind advection scheme to demonstrate the advantage of the TVD method for simulating steep density gradients and small‐scale density structures. These small‐scale density features result from time‐varying electric fields and are commonly observed using experimental techniques (e.g., incoherent scatter radar) in polar regions.
Probabilistic nonlinear prediction of river flows
Authors: Tamea S. , Laio F. , Ridolfi L.
Published: September 2005

In the recent past the nonlinear prediction (NLP) method, initially developed in the context of nonlinear time series analysis, has been successfully applied to river flow deterministic forecasting. In this work a probabilistic approach to the NLP method is proposed, which allows one to estimate the probability distribution of the predicted discharge values and to quantify the total uncertainty related to the forecast. An ensemble technique is also proposed in order to optimize the choice of the parameter values and to provide robustness to the model calibration. The probabilistic NLP method is applied to a river flow time series, giving results that confirm the effectiveness and reliability of the proposed approach.
External Validity of “Trivial” Experiments: The Case of Laboratory Aggression
Authors: Anderson Craig A. , Bushman Brad J.
Published: September 2005

The external validity of artificial “trivial” laboratory settings is examined. Past views emphasizing generalizability of relations among conceptual variables are reviewed and affirmed. One major implication of typical challenges to the external validity of laboratory research is tested with aggression research: If laboratory research is low in external validity, then laboratory studies should fail to detect relations among variables that are correlated with aggression in “real-world” studies. Meta-analysis was used to examine 5 situational variables (provocation, violent media, alcohol, anonymity, hot temperature) and 3 individual difference variables (sex, Type A personality, trait aggressiveness) in real-world and laboratory aggression studies. Results strongly supported the external validity of trivial laboratory studies. Advice is given on how scholars might handle occasional descrepancies between laboratory and real-world findings.
Esteem Threat, Self-Regulatory Breakdown, and Emotional Distress as Factors in Self-Defeating Behavior
Authors: Baumeister Roy F.
Published: September 2005

Patterns of human self-defeating or self-destructive behavior are examined in relation to several hypothesized causes. Threatened egotism appears to be a major, pervasive cause: Self-defeating responses are especially common when people feel that others may perceive them less favorably than the people desire. Self-regulation failure is also a common element in most self-defeating behavior. Emotional distress is often a precipitating factor. Several causal processes, including foolish risk taking and escapist responses, link emotional distress to self-defeat.
Consequences of Surprising Reward Omissions
Authors: Papini Mauricio R. , Dudley R. Thomas
Published: September 2005

A surprising reward omission (SRO) occurs when an appetitive reinforcer is not presented (or it is reduced in magnitude or quality) even though there are signals for its impending presentation. Evidence supporting the hypothesis that SROs produce an aversive emotional reaction with physiological and behavioral consequences is reviewed. SROs are followed by pituitary–adrenal activation; changes in immune function; odor emissions in rodents; distress vocalizations in rodents and primates; and increases in locomotion, aggressive behavior, drinking, and eating. SROs can support the acquisition of new escape responses and invigorate previously acquired responses. The review identifies common aspects of these phenomena and areas in which more research is needed.
Right Answers, Wrong Reasons: Revisiting the Deletion of Homosexuality from the DSM
Authors: Greenberg Gary
Published: September 2005

The deletion of homosexuality from DSM–II and subsequent diagnostic manuals is generally seen as a triumph of science over prejudice and oppression. An examination of actual circumstances of the deletion and of the changes that it engendered shows that this view overlooks crucial points. Specifically, the received version conceals the way that deletion served a nonscientific vision of justice, as well as that postdeletion practice regarding homosexuality is inescapably political and moral. These concealments help to maintain the mental health professions' claim to scientific authority, a claim that has little basis in fact. Furthermore, the deletion represented an inadvertent application of social constructionist principles to psychotherapeutic practice, one that makes clear the pragmatic value of postmodern psychologies to contemporary psychotherapy.
Introduction to Symposium on Constructing Self with Others
Authors: Barone David F.
Published: September 2005

The notion that the self is interpersonally embedded can be found throughout psychology's history. This article presents convergent work from different areas of contemporary psychology that supports and elaborates this notion. M. Baldwin's (1997) experimental work in social cognition demonstrates that self-evaluation varies with the relational schema that is activated. C. R. Snyder and R. L. Higgins (1997) present a social–cognitive personality theory of how people maintain their self theories to satisfy internal and external audiences. S. J. Blatt, J. S. Auerbach, and K. N. Levy's (1997) object-relations theory of the role of mental representations of self and others in psychopathology is supported by research that changes in these representations are associated with improvement in psychotherapy. J. Martin and J. Sugarman's (1997) social–cognitive theory of counseling and psychotherapy as conversational reconstructions of self theories also has research support and raises the issue of whether the self is agentic if socially constructed.
Confirmation Bias: A Ubiquitous Phenomenon in Many Guises
Authors: Nickerson Raymond S.
Published: September 2005

Confirmation bias, as the term is typically used in the psychological literature, connotes the seeking or interpreting of evidence in ways that are partial to existing beliefs, expectations, or a hypothesis in hand. The author reviews evidence of such a bias in a variety of guises and gives examples of its operation in several practical contexts. Possible explanations are considered, and the question of its utility or disutility is discussed.
Levels of Analysis and the Organization of Affect
Authors: Rosenberg Erika L.
Published: September 2005

This article presents a framework for the organization of affective processes, including the affective traits, moods, and emotions. Section 1 introduces the levels-of-analysis approach, defines the three levels of affect, presents criteria for ordering these levels hierarchically in terms of simple and complex temporally driven processes, and examines the interrelations among the various levels of affect, including an in-depth analysis of affective trait–emotion relationships. Section 2 offers an application of the hierarchical view to research on affect–cognition interactions, including a brief review of affect congruency effects and a discussion of the conceptual and empirical challenges to such research necessitated by consideration of the differences among the levels of affect.
The Emerging Field of Emotion Regulation: An Integrative Review
Authors: Gross James J.
Published: September 2005

The emerging field of emotion regulation studies how individuals influence which emotions they have, when they have them, and how they experience and express them. This review takes an evolutionary perspective and characterizes emotion in terms of response tendencies. Emotion regulation is defined and distinguished from coping, mood regulation, defense, and affect regulation. In the increasingly specialized discipline of psychology, the field of emotion regulation cuts across traditional boundaries and provides common ground. According to a process model of emotion regulation, emotion may be regulated at five points in the emotion generative process: (a) selection of the situation, (b) modification of the situation, (c) deployment of attention, (d) change of cognitions, and (e) modulation of responses. The field of emotion regulation promises new insights into age-old questions about how people manage their emotions.
Staining abnormalities of dermal collagen in cats with cutaneous asthenia or acquired skin fragility as demonstrated with Masson's trichrome stain
Authors: FERNANDEZ CHARLENE J. , SCOTT DANNY W. , ERB HOLLIS N. , MINOR RONALD R.
Published: September 2005

This retrospective study compared the Masson's trichrome staining properties of collagen in the skin of normal cats and cats with cutaneous asthenia or acquired skin fragility. A Masson's trichrome staining abnormality was seen in all (n= 8) cats with cutaneous asthenia, three of four cats with acquired skin fragility, and none (n= 10) of the normal cats. A grading system developed to classify the intensity and distribution of abnormally stained collagen fibres indicated that cats with cutaneous asthenia had higher scores (P< 0.001) than normal cats. Cats with acquired skin fragility had intermediate scores that were not significantly different from either of the other two groups.
Effect of polydispersity on the tensile modulus of diblock copolymers in a lamellar phase
Authors: Jiang Ying , Huang Rui , Liang Haojun
Published: September 2005

We have calculated the tensile moduli of nanomaterials having lamellar microstructures prepared through the self-assembly of a polydisperse diblock copolymer. We observed that the extensional moduli K33 provided the major contribution to the tensile modulus and that the value of K33 depended mainly on the contribution of K33U (the internal energy contribution to K33). We found that a larger polydispersity index (PDI) weakens the material for our polydisperse model; we attribute this phenomenon to the larger lamellar domain size at equilibrium when the polydispersity of the block increases and to the competition between short and long chains. We found that longer chains in this system strengthen the material, but shorter chains weaken it as a result of the influence of the PDI. The shear modulus contributed negligibly to the extensional moduli.
Integral equation theory for atactic polystyrene melt with a coarse-grained model
Authors: Zhao Lei , Li Yi-Gui , Mi Jianguo , Zhong Chongli
Published: September 2005

In this work, an integral equation approach to investigate the atactic polystyrene (aPS) melt based on polymer reference interaction site model (PRISM) theory is proposed. The intramolecular structure factors, required as input to PRISM theory, are obtained from the semiflexible chain model. With a novel coarse-graining procedure and the explicit-atom molecular-dynamics (MD) simulations for aPS, the parameters needed for the coarse-grained model are obtained by using an automatic simplex optimization. These parameters can be used to describe the structure and thermodynamic properties of the complex aPS melt and good agreement is obtained between the theory and MD simulations. The proposed integral equation approach provides a basis for describing the structure and properties of PS nanocomposites where the application of molecular simulation is difficult.
Microscopic ion fluxes in plasma-aided nanofabrication of ordered carbon nanotip structures
Authors: Levchenko I. , Ostrikov K. , Keidar M. , Xu S.
Published: September 2005

Three-dimensional topography of microscopic ion fluxes in the reactive hydrocarbon-based plasma-aided nanofabrication of ordered arrays of vertically aligned single-crystalline carbon nanotip microemitter structures is simulated by using a Monte Carlo technique. The individual ion trajectories are computed by integrating the ion equations of motion in the electrostatic field created by a biased nanostructured substrate. It is shown that the ion flux focusing onto carbon nanotips is more efficient under the conditions of low potential drop Us across the near-substrate plasma sheath. Under low-Us conditions, the ion current density onto the surface of individual nanotips is higher for higher-aspect-ratio nanotips and can exceed the mean ion current density onto the entire nanopattern in up to approximately five times. This effect becomes less pronounced with increasing the substrate bias, with the mean relative enhancement of the ion current density ξi not exceeding ∼1.7. The value of ξi is higher in denser plasmas and behaves differently with the electron temperature Te depending on the substrate bias. When the substrate bias is low, ξi decreases with Te, with the opposite tendency under higher-Us conditions. The results are relevant to the plasma-enhanced chemical-vapor deposition of ordered large-area nanopatterns of vertically aligned carbon nanotips, nanofibers, and nanopyramidal microemitter structures for flat-panel display applications.
Thermal-drag carrier cooling in undoped semiconductors
Authors: Huang Danhong , Apostolova T. , Alsing P. M. , Cardimona D. A.
Published: September 2005

An approach for carrier cooling in undoped and contactless semiconductors is proposed by using thermal-drag effects in comparison with other methods, such as direct resonant tunneling, nonresonant thermionic, and junction-tunneling cooling, as well as indirect optothermionic and thermoelectric cooling, of carriers in doped and contacted semiconductors. A four-step microscopic model is proposed for this thermal-drag carrier cooling in undoped semiconductors. Wide-band-gap semiconductors with small lattice specific heat and small exchange specific heat between carriers and phonons are found to achieve the best thermal-drag carrier cooling under near-band-edge interband pumping by a weak field. This indirect carrier cooling is accompanied by the lattice cooling. The carrier temperature is pinned to the lattice temperature due to ultrafast carrier-phonon scattering, and it is dragged down by the reduction of the lattice temperature, i.e., the thermal-drag effects.
Effect of self-interaction error in the evaluation of the bond length alternation in trans-polyacetylene using density-functional theory
Authors: Ciofini I. , Adamo C. , Chermette H.
Published: September 2005

The calculation of the bond-length alternation (BLA) in trans-polyacetylene has been chosen as benchmark to emphasize the effect of the self-interaction error within density-functional theory (DFT). In particular, the BLA of increasingly long acetylene oligomers has been computed using the Møller-Plesset wave-function method truncated at the second order and several DFT models. While local-density approximation (LDA) or generalized gradient corrected (GGA) functionals strongly underestimate the BLA, approaches including self-interaction corrections (SIC) provide significant improvements. Indeed, the simple averaged-density SIC scheme (ADSIC), recently proposed by Legrand et al. [J. Phys. B 35, 1115 (2002)], provides better results for the structure of large oligomers than the more complex approach of Krieger et al. [Phys. Rev. A 45, 101 (1992)]. The ADSIC method is particularly promising since both the exchange-correlation energy and potential are improved with respect to standard LDA/GGA using a physically appealing correction, through a different route than the more popular approach through the Hartree-Fock exchange inclusion within the hybrid functionals.
Edge instability regimes with applications to blob transport and the quasicoherent mode
Authors: Myra J. R. , D’Ippolito D. A.
Published: September 2005

An analytic theory of the resistive X-point (RX) mode in the edge region of a diverted tokamak is developed by employing an outgoing-evanescent wave boundary condition along the field lines. This result is employed to deduce a new categorization of edge instabilities in the presence of X points. A regime diagram shows the relationship of the RX mode to the ideal and conventional resistive ballooning modes. In addition to describing growth rates of linear instabilities, the analysis also yields regimes and scalings for nonlinear convective “blob” propagation velocities. The regime diagram and a knowledge of experimental and BOUT code simulation results suggest that the quasicoherent mode seen in the Alcator C-Mod tokamak [M. Greenwald, R. Boivin, P. Bonoli et al., [Phys. Plasmas 6, 1943 (1999)] can be classified as an electromagnetic RX mode. Analytical scalings for the existence of this mode compare well with experimental trends, as does the solution of a model radial eigenvalue problem. Finally, using a finite Larmor radius assumption to eliminate the perpendicular wave number, the instability regime diagram can be converted to an edge phase space diagram. X-point physics adds a new region to this edge parameter space that is postulated to be the enhanced D-alpha regime.
Influence of vibrational excitation on the nonadiabatic reactions of metal atoms with H2
Authors: Chen Jye-Jong , Hsiao Ming-Kai , Lin King-Chuen
Published: September 2005

The reactions of alkaline earth metal atoms, Mg(3s3pP11) and Ca(4s4pP11), with H2(v=1,j) are studied using a pump-probe technique combined with stimulated Raman pumping and coherent anti-Stokes Raman spectroscopy. For the Ca(4P11) case, the energy deposited in the v=1 level enlarges the H2 bond distance to help facilitate the reaction without opening an additional pathway. For the Mg(3P11) case, the vibrational excitation of H2 leads to enhancement of the low rotational component of the rotational distribution and the MgH(v=0)∕MgH(v=1) ratio. These results can be predicted with quasi-classical trajectory calculations and interpreted with a kinematic collision model.
Effect of nitrogen incorporation on improvement of leakage properties in high-k HfO2 capacitors treated by N2-plasma
Authors: Seong Nak-Jin , Yoon Soon-Gil , Yeom Seung-Jin , Woo Hyun-Kyung , Kil Deok-Sin , Roh Jae-Sung , Sohn Hyun-Chul
Published: September 2005

The nitrogen incorporation into the HfO2 films with an EOT (equivalent oxide thickness) of 9Å was performed by N2-plasma to improve the electrical properties. The dielectric properties and a leakage current characteristics of the capacitors were investigated as a function of plasma power and plasma treatment temperature. The dielectric constant of the capacitors is not influenced by nitrogen incorporation. The N2-plasma treatment at 300°C and 70W exhibits the most effective influence on improvement of the leakage current characteristics. Leakage current density of the capacitors treated at 300°C and 70W exhibits a half order of magnitude lower than that without plasma treatment. Nitrogen incorporated into the HfO2 films possesses the intrinsic effect that drastically reduce the electron leakage current through HfO2 dielectrics by deactivating the VO (oxygen vacancy) related gap states.
The influence of interface roughness on electrical transport in nanoscale metallic multilayers
Authors: Aurongzeb D. , Holtz M. , Berg J. M. , Chandolu A. , Temkin H.
Published: September 2005

We study the effects of annealing on the electrical resistivity of thin metallic multilayers of nickel and aluminum. Resistivity is seen to rise with anneal temperature. Above a specific temperature the resistivity decreases. We model this behavior based on the interface evolution due to the formation of intermetallic nanocrystals. The rise is attributed to interface roughening and to constraints placed on the electron mean-free paths by the nanocrystals. At high temperatures, the lateral coalescence preserves the smooth stratification producing the observed drop in film resistivity.
Exchange coupling between FePt and Fe through Ru interlayer
Authors: Jiang Jianhua , Tezuka N. , Inomata K.
Published: September 2005

Interlayer exchange coupling in magnetron-sputtered FePt∕Ru∕Fe trilayers has been investigated. The thickness dependence of in-plane magnetic properties of FePt thin films was investigated and a 12.5-nm-thick FePt film showed both high coercivity and good squareness. The exchange coupling between FePt and Fe layers through a Ru interlayer was obtained with an oscillatory period of about 1nm. A 0.5nm Ru layer produced a ferromagnetic coupling between the two magnetic layers and the saturated magnetization is considerably improved through interlayer exchange coupling with Fe.
The shock response of float-glass laminates
Authors: Bourne N. K.
Published: September 2005

Interfaces within glass targets give rise to variations in the mode of failure of material components. The wide use of such laminates merits further investigation of the failure mechanism. It is already known that when shocked above a threshold of 4GPa, glass fails under compression behind a propagating front following the compression front. Work is presented which indicates how this failure process is altered by bonding together two plates to introduce an interface, rather than leaving a monolithic target. After crossing an internal interface, the failure wave propagates only after a delay in soda-lime glass and the failed strength of the material is increased at the inner interface compared with that at the impact face. Addition of a second interface illustrates these effects. Recent work has shown that failure of more than two plates bonded together during impact shapes the pulse transmitted through materials. Indeed it has been suggested that glass sheets bonded together show some of the features of polycrystalline brittle materials. In this work, the stress has been monitored at different stations in the laminate to ascertain the effect of varying the number of tiles within the laminate. It is found that the pulse rises to ca. 4GPa quickly and then is ramped more gradually as the number of glass sheets is increased.
Lipid mixing upon deoxyribonucleic acid-induced liposomes fusion investigated by synchrotron small-angle x-ray scattering
Authors: Caracciolo Giulio , Pozzi Daniela , Caminiti Ruggero , Amenitsch Heinz
Published: September 2005

Multipart cationic lipid/deoxyribonucleic acid (DNA) complexes (lipoplexes) were prepared, for the first time, by adding linear fragments of DNA to mixed lipid dispersions containing two distinct populations of cationic liposomes exhibiting different lipid headgroups and a number of systematic variations in relevant physical-chemical parameters. Upon DNA-induced fusion of liposomes, large lipid mixing at the molecular level occurs. As a result, highly organized mixed lipoplexes form spontaneously. By varying the composition of lipid dispersion, the physical properties of the emerging lipid carrier, i.e., the surface charge density and membrane thickness, can be modulated and distinct DNA packing densities can also be achieved.
Inspection of magnetic semiconductor and clustering structure in CoFe-doped ZnO films by bias-dependent impedance spectroscopy
Authors: Huang J. C. A. , Hsu H. S.
Published: September 2005

Diluted magnetic semiconductor and cluster dominated structure of CoFe-doped ZnO films have been systematically investigated by bias-dependent impedance spectroscopy. The complex impedance spectroscopy of 5mol% CoFe-doped ZnO film can be fitted by an equivalent circuit employing two sets of parallel resistance (R) and capacitance (C) components in series, representing the oxide grain and grain boundary contribution, respectively. For 10mol% CoFe-doped ZnO film, a third RC component together with a single resistance element, which are likely due to the presence of metal clusters and metal-oxide interface, have to be taken into account to fit the impedance spectroscopy. By applying a dc bias of 0∼1.5V, the relaxation contribution from different structural origin can be clearly identified. The bias-dependent impedance spectroscopy demonstrates significant sensitivity to the formation of CoFe clusters in ZnO.
Efficient second harmonic generation from large band gap II-VI semiconductor photonic crystal
Authors: Yang H. , Xie P. , Chan S. K. , Zhang Z. Q. , Sou I. K. , Wong G. K. L. , Wong K. S.
Published: September 2005

Dramatic enhancement of second harmonic generation (SHG) near the photonic band edge was observed in a one-dimensional ZnSe∕ZnMgS semiconductor photonic crystal (PC) structure. Over two orders of magnitude increase in SHG intensity was observed at the photonic band edge at ∼1400nm compared to the nonphase matching region. The maximum SHG conversion efficiency of 0.8% is observed in only seven micrometers length of crystal. This enhancement came from a combination of large ZnSe second order susceptibility coefficient (χ(2)), high density of optical modes and phase matching of the fundamental and second harmonic waves near the photonic band edge due to modification of the dispersion curve by the PC structure.
Self-assembled nanoporous electrodes for sensitive and labeling-free biomolecular recognition
Authors: Liu Jun , Huo Qisheng
Published: September 2005

We fabricated nanoporous electrodes with uniform pore sizes using surfactant self-assembly techniques. These nanoporous electrodes were functionalized. When the target biomolecules are captured in the pore channels through specific binding or hybridization, the nanopores are totally or partially blocked. As a result, the access of indicator molecules to the conductive surface of the electrode is affected, and the electrochemical response on the electrode is reduced. This mechanism is sensitive to the presence of nanomole (10−9mole) to femtomole (10−15mole) level molecules and has potential as a simple, general, and labeling-free technique for electrochemical biomolecular recognition.
Unconventional exchange bias in oxide-coated manganese nanoparticles
Authors: Si P. Z. , Li D. , Lee J. W. , Choi C. J. , Zhang Z. D. , Geng D. Y. , Brück E.
Published: September 2005

We report unconventional exchange bias in oxide-coated manganese nanoparticles, in which the Curie temperature of Mn3O4 shell is lower than the Néel temperature of the antiferromagnetic core. The coercivity (873kA∕m) of the nanoparticles, which is more than four times greater than that of bulk Mn3O4, has been enhanced significantly. A considerable enhancement in Curie temperature compared to the bulk was also observed for Mn3O4 in nanoscale. An exchange bias field as large as 400kA∕m was observed due to the strong interfacial exchange coupling. A simple phenomenological model is given to understand these phenomena in this ferri/antiferromagnetic system.
Neutron Reflectometry of Membrane Protein Assemblies at the Solid/Liquid Interface
Authors: Holt Stephen A. , Lakey Jeremy H. , Daud Sofian M. , Keegan Neil
Published: September 2005

Neutron reflectometry has been used to study the self-assembly of a membrane protein, OmpF, onto a gold-coated silicon substrate from solution. OmpF associates into trimers and has been modified so that each trimer binds to the gold substrate through cysteine residues. Quantitative analysis of the data revealed that 12% of the surface was covered by the oriented protein with 27600 water molecules surrounding each trimer.
Controlled Growth of Sonochemically Synthesized Gold Seed Particles in Aqueous Solutions Containing Surfactants
Authors: Okitsu Kenji , Teo Boon Mian , Ashokkumar Muthupandian , Grieser Franz
Published: September 2005

Gold seed particles stabilized by citric acid were prepared by the sonochemical reduction of Au(iii) ions in aqueous solutions. These seed particles were grown by the reduction of adsorbed Au(iii) ions by ascorbic acid in aqueous solutions containing cationic surfactants, dodecyltrimethylammonium bromide (C12TAB), hexadecyltrimethylammonium bromide (C16TAB) and didodecyldimethylammonium bromide (DDDAB). The rate of reduction of Au(iii) ions during the seed-growth process was found to be strongly dependent upon the type and concentration of the cationic surfactants. The presence of Ag(i) in the growth solution containing DDDAB affected the size distribution of the gold particles.
Giant-block twist grain boundary smectic phases
Authors: Fernsler J. , Hough L. , Shao R.-F. , Maclennan J. E. , Navailles L. , Brunet M. , Madhusudana N. V. , Mondain-Monval O. , Boyer C. , Zasadzinski J. , Rego J. A. , Walba D. M. , Clark N. A.
Published: September 2005

Study of a diverse set of chiral smectic materials, each of which has twist grain boundary (TGB) phases over a broad temperature range and exhibits grid patterns in the Grandjean textures of the TGB helix, shows that these features arise from a common structure: “giant” smectic blocks of planar layers of thicknesslb> 200 nm terminated by GBs that are sharp, mediating large angular jumps in layer orientation between blocks (60° < Δ < 90°), and lubricating the thermal contraction of the smectic layers within the blocks. This phenomenology is well described by basic theoretical models applicable in the limit that the ratio of molecular tilt penetration length-to-layer coherence length is large, and featuring GBs in which smectic ordering is weak, approaching thin, melted (nematic-like) walls. In this limit the energy cost of change of the block size is small, leading to a wide variation of block dimension, depending on preparation conditions. The models also account for the temperature dependence of the TGB helix pitch.
Highways of gene sharing in prokaryotes
Authors: Beiko Robert G. , Harlow Timothy J. , Ragan Mark A.
Published: September 2005

The extent to which lateral genetic transfer has shaped microbial genomes has major implications for the emergence of community structures. We have performed a rigorous phylogenetic analysis of >220,000 proteins from genomes of 144 prokaryotes to determine the contribution of gene sharing to current prokaryotic diversity, and to identify “highways” of sharing between lineages. The inferred relationships suggest a pattern of inheritance that is largely vertical, but with notable exceptions among closely related taxa, and among distantly related organisms that live in similar environments.
Effect of condensate formation on long-distance radical cation migration in DNA
Authors: Das Prolay , Schuster Gary B.
Published: September 2005

Long-distance radical cation transport was studied in DNA condensates. Linearized pUC19 plasmid was ligated to an oligomer containing a covalently linked anthraquinone group and six regularly spaced GG steps, which serve as traps for the migrating radical cation. Treatment of the linear, ligated plasmid with spermidine results in formation of condensates that were detected by light scattering and observed by transmission electron microscopy. Irradiation of the anthraquinone group in the condensate causes long-distance charge migration, which is detected by reaction at the remote guanines. The efficiency of charge migration in the condensate is significantly less than it is for the corresponding oligomer in solution. This result is attributed to a lower mobility for the migrating radical cation in the condensate, which is caused by inhibited formation of charge-transfer-effective states.