bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of isobaric product ions in electrospray ionization mass spectra of fentanyl using multistage mass spectrometry and deuterium labeling
Authors: Wichitnithad Wisut , McManus Terence J. , Callery Patrick S.
Published: December 2010

Isobaric product ions cannot be differentiated by exact mass determinations, although in some cases deuterium labeling can provide useful structural information for identifying isobaric ions. Proposed fragmentation pathways of fentanyl were investigated by electrospray ionization ion trap mass spectrometry coupled with deuterium labeling experiments and spectra of regiospecific deuterium labeled analogs. The major product ion of fentanyl under tandem mass spectrometry (MS/MS) conditions (m/z 188) was accounted for by a neutral loss of N‐phenylpropanamide. 1‐(2‐Phenylethyl)‐1,2,3,6‐tetrahydropyridine (1) was proposed as the structure of the product ion. However, further fragmentation (MS3) of the fentanyl m/z 188 ion gave product ions that were different from the product ion in the MS/MS fragmentation of synthesized 1, suggesting that the m/z 188 product ion from fentanyl includes an isobaric structure different from the structure of 1. MS/MS fragmentation of fentanyl in deuterium oxide moved one of the isobars to 1 Da higher mass, and left the other isobar unchanged in mass. Multistage mass spectral data from deuterium‐labeled proposed isobaric structures provided support for two fragmentation pathways. The results illustrate the utility of multistage mass spectrometry and deuterium labeling in structural assignment of isobaric product ions. Copyright © 2010 John Wiley & Sons, Ltd.
Mass spectrometric characterization of metal triflates and triflimides (Lewis superacid catalysts) by electrospray ionization and tandem mass spectrometry
Authors: Monfardini Ilaria , Massi Lionel , Tremel Pascale , Hauville Agnès , Olivero Sandra , Duñach Elisabet , Gal Jean‐François
Published: December 2010

Trifluoromethylsulfonate (triflate) and bis(trifluoromethylsulfonyl)imide (triflimide) salts, well‐known Lewis acid catalysts, present some difficulty in their characterization. By using nitromethane as the solvent, useful electrospray mass spectra in positive and negative ion mode were obtained for salts of metals in oxidation states +2 and +3. In positive mode, addition of a strong Lewis base (triphenylphosphine oxide, TPPO), capable of displacing a triflate (TfO−) or a triflimide (Tf2N−) anion, is necessary for obtaining useful spectra. Under these conditions of solvent and added ligand, the most abundant ions were [M2+(A−)(TPPO)2]+ or [M3+(A−)2(TPPO)2]+ with A− = TfO− or Tf2N−. The MS/MS spectra of these diagnostic ions provide additional analytical information. The breakdown curves, in the form of % dissociated as a function of the ion activation energy, offer a mean for investigating the bonding in these ions. Copyright © 2010 John Wiley & Sons, Ltd.
Design and performance of an evolved gas analysis ion attachment mass spectrometer
Authors: Takahashi Seiji , Tsukagoshi Masamichi , Kitahara Yuki , Juhász Márta , Fujii Toshihiro
Published: December 2010

We designed a simple evolved gas analysis (EGA) system to act as a sampler between solid samples at atmospheric pressure and the high vacuum inside a mass spectrometer. The newly designed stainless steel system is simple, small and rugged and fulfills all the basic requirements for EGA. The temperature is programmable with 60°C/min as the maximum heating rate and the temperature range is up to 600°C. With this system coupled with lithium ion attachment mass spectrometry (IAMS), it is possible to study the temperature‐programmed decomposition of a number of solid materials by detecting any chemical species on a real‐time basis. For illustrative purposes, EGA‐IAMS experiments of polyethylene polymers have been conducted. Copyright © 2010 John Wiley & Sons, Ltd.
Rapid probe and isolation of bioactive compounds from Dioscorea panthaica using human serum albumin functionalized magnetic nano‐particles (HSA‐MNPs)‐based ligand fishing coupled with electrospray ionization mass spectrometry
Authors: Qing Lin‐Sen , Shan Xiao‐Qing , Xu Xue‐Min , Xue Ying , Deng Wen‐Long , Li Bo‐Gang , Wang Xiao‐Ling , Liao Xun
Published: December 2010

The chemical diversity of secondary metabolites in medicinal plant makes it a huge challenge to isolate the bioactive compounds from herbal extracts, so quick recognition of the bioactive ones is of vital importance for improving the efficiency of isolation. In this study, a ligand fishing experiment based on human serum albumin functionalized magnetic nano‐particles (HSA‐MNPs) was performed to probe the bioactive components in a traditional Chinese medicinal plant, Dioscorea panthaica. The minor compounds fished out by HSA‐MNPs were identified by electrospray ionization mass spectrometry (ESI‐MS), and then separated from the extract of the whole plant by one or two steps of column chromatography under the guidance of ESI‐MS. Four biologically active compounds, progenin II, progenin III, dioscin and gracillin, were isolated much faster than in the normal lengthy phytochemical procedure. The present study demonstrates that biological macromolecule (protein, enzyme, receptor, et al.) functionalized MNPs may serve as baits to recognize bioactive small molecules in complex herbal extracts. It is expected that a macromolecule functionalized MNPs‐based ligand fishing experiment coupled with ESI‐MS may accelerate the process of identification and isolation of bioactive components from medicinal plants, and thus benefit the speed of drug discovery. Copyright © 2010 John Wiley & Sons, Ltd.
Effects of the topographic niche differentiation on the coexistence of major and minor species in a species‐rich temperate forest
Authors: Suzuki Maki
Published: December 2010

Topographic niche differentiation (TND) is believed to facilitate the coexistence of tree species, but its effects are not well established for minor species or for life stages beyond recruitment. In this study, the effects of topography (slope inclination and topographic configuration) on the demographic parameters (mortality, diameter growth rate and recruitment rate) of both major and minor species in a species‐rich temperate forest were examined using a mixed‐model approach. The model selection analysis detected interspecies difference in the response of recruitment rate to topographic configuration. However, mortality and diameter growth rate of stems with DBH ≥ 5 cm did not show any species‐specific response to two topographic parameters. The recruitment rate of major species tended to be higher under topographic conditions where many stems of the species already existed, suggesting significant habitat segregation. No such correlation was found for minor species. These results suggest TND has a limited effect on habitat segregation among species, and that other mechanisms also contributed to coexistence, especially when considering minor species.
Calcium carbonate suppresses haem toxicity markers without calcium phosphate side effects on colon carcinogenesis
Authors: Allam Ossama , Bahuaud Diane , Taché Sylviane , Naud Nathalie , Corpet Denis E. , Pierre Fabrice H. F.
Published: December 2010

Red meat intake is associated with an increased risk of colorectal cancer. We have previously shown that haemin, Hb and red meat promote carcinogen-induced preneoplastic lesions, aberrant crypt foci (ACF), in the colon of rats. We have also shown that dietary calcium phosphate inhibits haemin-induced promotion and normalises faecal lipoperoxides and cytotoxicity. Unexpectedly, high-calcium phosphate control diet-fed rats had more preneoplastic lesions in the colon than low-Ca control diet-fed rats. The present study was designed to find a Ca supplementation with no adverse effect, by testing several doses and types of Ca salts. Onein vitrostudy and two short-term studies in rats identified calcium carbonate as the most effective Ca salt to bind haemin vitroand to decrease faecal biomarkers previously associated with increased carcinogenesis: faecal water cytotoxicity and thiobarbituric acid-reactive substances. A long-term carcinogenesis study in dimethylhydrazine-injected rats demonstrated that a diet containing 100 μmol/g calcium carbonate did not promote ACF, in contrast with a previously tested calcium phosphate diet. The results suggest that calcium carbonate, and not calcium phosphate, should be used to reduce haem-associated colorectal cancer risk in meat eaters. They support the concept that the nature of the associated anion to a protective metal ion is important for chemoprevention.
Effect of the dietary polyphenolic fraction of chicory root, peel, seed and leaf extracts on caecal fermentation and blood parameters in rats fed diets containing prebiotic fructans
Authors: Juśkiewicz Jerzy , Zduńczyk Zenon , Żary-Sikorska Ewa , Król Bogusław , Milala Joanna , Jurgoński Adam
Published: December 2010

The aim of this 28 d experiment was to examine the physiological response of growing rats to a dietary combination of prebiotic chicory fructans, with polyphenols originating from different parts of the chicory plant, i.e. roots, root peels, seeds and leaves. A total of forty rats were assigned to groups fed the following diets characterised by a similar content of oligofructose and inulin: control, with 10 % of a root extract (a low level of dietary polyphenols, 0·05 %), with 6·5 % of a root peel extract (a medium level of dietary polyphenols, 0·107 %), with a combination of 8 % of a peel extract and 0·8 % of a seed extract (a high level of dietary polyphenols, 0·208 %) and with 2·5 % of a leaf extract (a medium level of dietary polyphenols, 0·106 %, with chicoric acid constituting half of them). Chicory seeds are the richest source of polyphenols, especially abundant in dicaffeoylquinic acids. When applied as a dietary supplement, the mixture of monocaffeoylquinic and dicaffeoylquinic acids, from the extracts made of roots, root peels and seeds, elicited more favourable changes in parameters of the antioxidative status of the body and in the activity of bacterial β-glucuronidase in the faeces and caecal digesta. In turn, the extract from chicory leaves, containing considerable quantities of chicoric acid and polyphenolic glycosides, apart from chlorogenic acids, also triggered desirable changes in the lipid profile of the blood serum. The high concentration of polyphenols in the extracts examined enables their application as dietary supplements to be administered in low doses.
The Politics of Symbols, Semantics, and Sentiments in the Weimar Republic
Authors: Canning Kathleen
Published: December 2010

Contests over the termpolitics, over the boundaries that distinguished politics from non-politics, were one of the distinguishing features of the Weimar Republic. Not only did the disciplines of history, philosophy, law, sociology, and pedagogy each define this boundary in different terms, but participants in the debate also distinguished between ideal and real politics, politics at the level of state, and the dissemination of politics through society and citizenry. The fact that Weimar began with a revolution, the abdication of theKaiser, and military defeat meant an eruption of politicization in 1918–19, whereby political organs of state and civil society sought in unprecedented fashion to draw Germans into parties and parliaments, associations, and activist societies. “The German people would still consist of ninety percent unpolitical people, if Social Democracy had not become a political school for the people,” Otto Braun claimed inVorwärtsin 1925. Politics and politicization generated not only political acts—votes, strikes, and vocal demonstrations—but also cultural milieus of Socialists and Communists, Catholics and liberal Democrats, nationalists, and eventually Nazis. In Weimar Germany there was little room for the “unpolitical” citizen of the prewar era, held up as a model in a famous tract of 1918 by Thomas Mann.
With a Passion for Reason: Celebrating the Constitution in Weimar Germany
Authors: Achilles Manuela
Published: December 2010

It has long been held that Weimar democracy lacked the symbolic appeal necessary to bind collective sentiment and to win popular support. While recent revisionist histories of Weimar politics and culture take their cue from Peter Fritzsche's argument that “Weimar is less a cumulative failure than a series of bold experiments,” the turn toward new approaches and perspectives is uneven and incomplete even in those studies that avoid conflating the fragility of Weimar democracy with the overall lack or absence of democratic identifications. Detlev Peukert, while admonishing his readers not to minimize the Weimar experiment in democracy, also argues that the first German republic had no founding ritual, and that this absence in national history attests to a general lack of legitimacy. Eric Weitz, in his eloquent survey of the republic's promises and tragedy, has little to say about the proponents and forms of Weimar democratic culture. Thomas Mergel, who shows that the Weimar parliament was marked by a cooperative atmosphere of pragmatic republicanism, attributes to the republican Left a certain tendency “toward a rationalistic understanding of politics, toward the underestimation of the emotional attachment to a flag.” This assessment is entirely in line with the earlier claim that the rationalistic optimism (Gotthard Jasper) of the republican forces led to a “consequential underestimation of the integrative power of state symbols” (Klaus Wippermann).
RISKY SEXUAL BEHAVIOUR AMONG UNMARRIED YOUNG PEOPLE IN CAMEROON: ANOTHER LOOK AT FAMILY ENVIRONMENT
Authors: DIMBUENE ZACHARIE TSALA , DEFO BARTHELEMY KUATE
Published: December 2010

Most studies of the association between family structure and risky sexual behaviour among adolescents and young adults have employed a risk perspective which assumes that, compared with other types, two-parent families are protective. Drawing from a positive-oriented approach in this study, it is hypothesized that within each family type some influential factors may mitigate such anticipated deleterious effects of non-intact families and decrease sexual risk-taking. The paper examines specifically the effects of risk and protective factors with an emphasis on family processes associated with resilience, using data from a pooled sample of 1025 females and males aged 12–24 years from Bandjoun (West Cameroon). Findings show that the quality of parent/guardian–youth relationships significantly decreases the odds of risky sexual behaviour by 36%, 65% and 50% in neither-, one- and two-parent families, respectively. For two-parent families only, parental control acts as a significant protective factor; it decreased by 41% the odds of risky sexual behaviour. Programmatically, protective family factors such as parent/guardian–youth interactions need to be promoted to improve the efficiency of reproductive health and HIV interventions in sub-Saharan Africa.
From the Heyang Model to the Shaanxi Model: Action Research on Women's Participation in Village Governance
Authors: Xiaoxian Gao
Published: December 2010

In the fifth village elections in 2003 in Shaanxi province only 184 women were elected as village heads, a mere 0.6 per cent of the total. By the sixth elections in 2006 the number had almost doubled, and by the seventh elections in 2009 it had increased to 544. Together with the women on village Party committees, there were now 1,193 women village officials throughout the province, 4.5 per cent of the total. In contrast to leading women cadres within the formal structures of the political system, these village heads owed their positions not to nomination by upper levels of Party and government leadership but to success in fiercely competitive elections. Their success was the result of a grass-roots movement launched by a civil organization, the Shaanxi Research Association for Women and Family, to mobilize women's political participation. Their activities and trajectories had an impact on the local gender division of labour and entrenched gender attitudes that far surpassed the numbers alone. This article examines the collaboration between the Shaanxi Research Association for Women and Family and the All-China Women's Federation to mobilize women's political participation in Heyang county, Shaanxi province. It particularly focuses on the role of the Research Association in drawing on international feminist practices of women's empowerment to provide participatory based gender training courses as the key to persuading women to confront local and institutional resistance. Collaboration between the Research Association and the Women's Federation opened up access to significant resources both within and outside the system, creating new spaces for the articulation and protection of women's rights. Originating in a grass-roots movement, this collaboration can be seen as an instance of China's contemporary movement for gender equality.
The Gender of Communication: Changing Expectations of Mothers and Daughters in Urban China
Authors: Evans Harriet
Published: December 2010

In the flow of the material, cultural and moral influences shaping contemporary Chinese society, individual desires for emotional communication are reconstituting the meaning of the subject, self and responsibility. This article draws on fieldwork conducted in Beijing between 2000 and 2004 to discuss the gendered dimensions of this process through an analysis of the implications of the “communicative intimacy” sought by mothers and daughters in their mutual relationship. What could be termed a “feminization of intimacy” is the effect of two distinct but linked processes: on the one hand, a market-supported naturalization of women's roles, and on the other, the changing subjective articulation of women's needs, desires and expectations of family and personal relationships. I argue that across these two processes, the celebration of a communicative intimacy does not signify the emergence of more equal family or gender relationships, as recent theories about the individualization and cultural democratization of daily life in Western societies have argued. As families and kin groups, communities and neighbourhoods are physically, spatially and socially broken up, and as gender differences in employment and income increase, media and “expert” encouragement to mothers to become the all-round confidantes, educators and moral guides of their children affirms women's responsibilities in the domestic sphere. Expectations of mother–daughter communication reshape the meaning – and experience – of the individual subject in the changing character of the urban family at the same time as they reinforce ideas about women's gendered attributes and the responsibilities associated with them.
Apparent-time evolution of /l/ in one African American community
Authors: van Hofwegen Janneke
Published: December 2010

In the wake of numerous analyses of vowels in African American English (AAE), this study examines acoustically the phonetic production of a consonant—the word-initial lateral /l/—across several generations of speakers from a long-standing African American community in central North Carolina. The results of the study show that /l/ is darker in younger AAE speakers than in older ones, independent of phonetic context. Comparisons with ex-slave recordings suggest that a light variant of /l/ may be a substrate feature of AAE that has changed in recent decades. Additional comparisons with regional European Americans suggest that the darkening may be due to convergence with majority American English dialects.
NARRATING INSANITY IN THE LETTERS OF THOMAS MULOCK AND DINAH MULOCK CRAIK
Authors: Bourrier Karen
Published: December 2010

Scholars have had a difficult time assessing the significance of Dinah Mulock Craik (1824–1887), best remembered as the author of John Halifax, Gentleman (1856). The critical verdict on her life and letters has swung toward extremes. Some critics have seen her, to quote Henry James, as “kindly, somewhat dull, pious, and very sentimental” (172); her novels embody the Victorian values of self-help, moral earnestness, and hard work, and it is assumed that her life did too. Elaine Showalter's and Sally Mitchell's feminist recoveries of Craik's work in the 1970s and early 1980s found that just the opposite was true, and that Victorian sentimentality allowed Craik to voice the subversive desires of her female readers covertly, in a form that was acceptable to the general public (Showalter 5–7, Mitchell 31). This critical tradition tended to overemphasize the melodramatic aspects of Craik's life and career as a means of dramatizing the struggles of women in a patriarchal society. The most recent scholarship eschews Craik's life altogether for the most part, focusing on her novelistic representations of disability, of Irish and Scottish nationality, and of class and enfranchisement. This criticism engages Craik's writing as an interesting cultural artifact rather than as an aesthetic object: her work is once again seen as embodying normative Victorian values, but to what extent the author was the cognizant promoter of these values, and to what extent she was their unwitting filter, and whether it matters, is unclear. But new archival work shows the importance of her life in understanding her career. The Mulock Family Papers, held at the University of California at Los Angeles, underscore Craik's challenges in managing an abusive father, who suffered from periods of dejection followed by periods of great happiness, and who was frequently absent and incarcerated. Craik was intensely private when it came to her personal life, and scholars like Showalter have read her reserve as a bow to womanly decorum in a life otherwise dominated by literary celebrity. But the archive suggests that Craik's taciturnity was instead a strategy for managing the threat of violence and scandal.
The Politics of Intercountry Adoption: Explaining Variation in the Legal Requirements of Sub-Saharan African Countries
Authors: Breuning Marijke , Ishiyama John
Published: December 2010

What determines whether a country has more or less restrictive policies regarding intercountry adoption? Despite the growing importance of intercountry adoption as a political issue, and as an explicitly human face of globalization, there is virtually no systematic empirical work on intercountry adoption. We introduce a measure of the restrictiveness of the adoption laws in Sub-Saharan African countries and test possible explanations for the variations in legal restrictions on intercountry adoption among these countries.

Factors that are commonly cited as explanations for the restrictiveness of intercountry adoption policies do not hold up very well in our assessment. Openness to adoption is not determined by the severity of the orphan crisis or the AIDS crisis within the sending country, nor are democratic countries more responsive to the needs of their orphans. Additionally, African signatories to the Hague Convention, which aimed to increase transparency and accountability in intercountry adoption, tend to be among the most restrictive. On the other hand, a stronger connection with the global economy is associated with greater openness to intercountry adoption. We conclude with a discussion of the implications for orphans and for intercountry adoption.
Optimal estimation of the present‐day global methane budget
Authors: Neef Lisa , van Weele Michiel , van Velthoven Peter
Published: December 2010

Historical observations of the 13C/12C ratio of atmospheric CH4 are used to constrain the present‐day methane budget using optimal estimation. Three methane emission scenarios with basis in the recent literature are evaluated against historical 13CH4 observations, considering all uncertainties together. We estimate that present‐day methane emissions are composed of 64%–76% biogenic, 19%–30% fossil, and 4%–6% pyrogenic sources. It is found that, barring any changes in the isotopic signatures of sources and sink processes, satisfying the 13C/12C record requires estimates of present‐day anthropogenic fuel‐related emissions that are on the high end of the assumed uncertainties, even when a significant geological source is included. Extending present‐day results to the time of the Last Glacial Maximum (LGM), emissions from wetlands are implied to be 40%–62% of the present‐day value, the higher number being valid only for a scenario with strong (∼30 Tg/a) geological emissions and roughly 20% greater biomass burning emissions at LGM relative to the present‐day.
New constraints on the properties of the Yellowstone mantle plume from P and S wave attenuation tomography
Authors: Adams David C. , Humphreys Eugene D.
Published: December 2010

We estimate attenuation (t*) for teleseismic P and S arrivals to seismometers in the Yellowstone Intermountain Seismic Array; tomographically invert these data for upper mantle Qp‐1 and Qs‐1 structure; and, with the aid of the upper mantle velocity model of Waite et al. (2006), interpret the results for mantle temperature, partial melt, and water content. Because attenuation analysis is susceptible to contamination by noise, we employ time‐ and frequency‐domain analyses and a careful assessment of the uncertainty associated with each estimate by using the misfit between actual and predicted traces or spectra. The greatest noise source is signal‐generated noise, which affects S wave results more than P wave results. S waves also appear more susceptible to the effects of plume focusing. We find the upper mantle to be highly attenuative, but that above 200–250 km the low‐velocity plume is progressively less attenuative than the adjacent mantle with decreasing depth. We conclude that water dissolved in mantle minerals causes the upper mantle to be highly attenuative, that the Yellowstone plume is only ~50°C warmer than the surrounding mantle below the North America lithosphere, and that melting within this plume begins at depths of 200–250 km. We attribute the lower attenuation in the partially molten plume to the dehydration of the solid matrix as water partitions into the melt. The source of the upper mantle hydration is attributed to subduction, including water flux from a hydrated transition zone and Laramide‐age shallow subduction and direct hydration of North America lithosphere.
Dense water formation in the Laptev Sea flaw lead
Authors: Dethleff Dirk
Published: December 2010

Two primitive equation‐based models are used to estimate the formation of total volumes either of Arctic cold halocline water (CHW), intermediate water (IMW), or deep water (DW) through freeze‐related salt rejection in the Siberian Laptev Sea flaw lead system. Model A assumes that the rejected salt remixes with surface mixed water (SMW) beyond the leads until salinities allow for contribution to the midlayers of either the CHW, the IMW, or the DW. Model B simulates direct salt rejection to the upper layer of the cold halocline, and, after remixing here, further contribution to the midlayers of CHW, IMW, or DW. Averaging both model estimates, Laptev leads contribute either 0.161 Sv of CHW, 0.075 Sv of IMW, or 0.065 Sv of DW, which represents as much as ∼23%, ∼16%, or ∼30% of Arctic‐wide lead derived dense water contribution to the appropriate layer, respectively. Northwestern Laptev leads produce the greatest amount of dense water. These lead sections show very short buoyancy equilibrium timescales (∼6 to ∼13 days), and local dense water production may potentially be amplified by lateral brine injection into the cold halocline through bottom eddies. Central‐southern and southeastern leads generally produce little salt due to low surface water salinities. As definite separation mechanisms and proportion distributions of rejected lead brines into CHW, IWM, and DW are still unidentified in nature, a combination of lead salt rejection and remixing (model A) and direct downward expulsion of brine packages (model B) is assumed to steer Laptev lead dense water production.
Recoverable degradation in InAs/AlSb high-electron mobility transistors: The role of hot carriers and metastable defects in AlSb
Authors: Shen X. , DasGupta S. , Reed R. A. , Schrimpf R. D. , Fleetwood D. M. , Pantelides S. T.
Published: December 2010

Recent observations of electrical stress-induced recoverable degradation in InAs/AlSb high-electron mobility transistors (HEMTs) have been attributed to metastable defects in the AlSb layer generated by the injected holes. Here we present a detailed theoretical analysis of the degradation mechanism. We show that recoverable degradation does not require the presence of hot carriers in the vicinity of the defects but the degradation is enhanced when the injected holes become more energetic. The metastable degradation arises without the presence of an energy barrier. A comprehensive survey of candidate defects suggest that substitutional and interstitial oxygen are responsible for the degradation. Therefore, reducing the oxygen contamination during device fabrication is likely to significantly improve the reliability of InAs/AlSb HEMTs.
Enhancement of perpendicular coercivity in L11 CoPt thin films by replacement of Co with Cu
Authors: Yuan Fu-Te , Sun An-Cheng , Hsu Jen-Hwa , Tan C. S. , Kuo P. C. , Liao W. M. , Lee H. Y.
Published: December 2010

Magnetic properties and microstructures of L11 (Co50−xCux)Pt50 films sputter-deposited at 350 °C on MgO(111) substrates are reported. The addition of Cu significantly improves the alignment of c-axis and chemical ordering. Perpendicular coercivity (Hc⊥) also increases markedly from 0.1 to 1.9 kOe while in-plane coercivity declines from 0.5 to 0.07 kOe for the 20 nm thick films at x=26. Similar phenomena are observed with larger effects for the 50 nm thick films. The coercive mechanism is attributed to domain-wall pinning produced by the compositional segregation of nanoscaled nonmagnetic Cu-rich and magnetic Co-rich regions within a coherent L11 crystal domain. Therefore, an intermediate value of Hc⊥ can be obtained from this hardening mechanism when further microstructure modifications are enforced, which largely increases the potential for the use in spintronic devices or patterned media.
Observation and regime classification of pulsation patterns in expanding spherical flames
Authors: Jomaas G. , Law C. K.
Published: December 2010

The development of pulsating instability in expanding spherical premixed flames was experimentally studied, leading to the observation and quantification of spiral waves and target patterns over the flame surfaces in rich hydrogen-air, rich hydrogen-oxygen, and lean butane-oxygen-helium mixtures at elevated pressures. The transition boundary to instability was found to agree well with the Sivashinsky criterion, Ze(Le−1)>4(1+3)≈10.9, provided that local values are used in the evaluation of the Zel’dovich number, Ze, and the Lewis number, Le. The similarities to observations on Belousov–Zhabotinsky-reactions are noteworthy, and the present results provide new insights into the appearance order of various reactive-diffusive patterns on the reactive surface while transitioning from the stable domain into the unstable domain.
Magnetic properties of full-Heusler alloy Co2Fe1−xMnxAl films grown by molecular-beam epitaxy
Authors: Meng K. K. , Wang S. L. , Xu P. F. , Chen L. , Yan W. S. , Zhao J. H.
Published: December 2010

We have investigated magnetic properties of single-crystalline full-Heusler alloy Co2Fe1−xMnxAl films (0<x<1) grown on GaAs (001) by molecular-beam epitaxy at different temperatures. It is found that as x increases, the films grown at 160 °C have complex magnetic phases, but show pure ferromagnetic properties when grown at 280 °C. We attribute this magnetic behavior to the competition between ferromagnetic and antiferromagnetic Mn–Mn interactions, which are proved by x-ray magnetic circular dichroism measurements. Moreover, we have investigated in-plane magnetic anisotropies of Co2Fe1−xMnxAl films with pure ferromagnetic phases and deduced the corresponding anisotropy constants which also remarkably depend on x.
Measuring the electron density gradients of dense plasmas by deflectometry using short-wavelength probe
Authors: Nejdl J. , Kozlová M. , Mocek T. , Rus B.
Published: December 2010

A new and simple experimental technique for the measurement of electron density gradients in dense laser-produced plasmas using an electromagnetic wave probe is presented. The main advantage of this method is the low requirements on coherence of the probing beam. The method is based on measuring the deformation of the Talbot pattern of a two-dimensional grating that stems from the distortion of the probe beam wave-front caused by the gradients of the index of refraction. The compromise between spatial resolution and sensitivity for the given wavelength of the probe beam is set by the experimental design. The proposed technique was experimentally verified on plasmas that were created by either a point focus or a line focus of a laser interacting with various solid targets. In the experiments reported here, all plasmas were probed by a Ne-like Zn x-ray laser beam at 21.2 nm, but the technique is applicable for any wavelength of the probe.
MHC class I modulates NMDA receptor function and AMPA receptor trafficking
Authors: Fourgeaud Lawrence , Davenport Christopher M. , Tyler Carolyn M. , Cheng Timothy T. , Spencer Michael B. , Boulanger Lisa M.
Published: December 2010

Proteins of the major histocompatibility complex class I (MHCI) are known for their role in immunity and have recently been implicated in long-term plasticity of excitatory synaptic transmission. However, the mechanisms by which MHCI influences synaptic plasticity remain unknown. Here we show that endogenous MHCI regulates synaptic responses mediated by NMDA-type glutamate receptors (NMDARs) in the mammalian central nervous system (CNS). The AMPA/NMDA ratio is decreased at MHCI-deficient hippocampal synapses, reflecting an increase in NMDAR-mediated currents. This enhanced NMDAR response is not associated with changes in the levels, subunit composition, or gross subcellular distribution of NMDARs. Increased NMDAR-mediated currents in MHCI-deficient neurons are associated with characteristic changes in AMPA receptor trafficking in response to NMDAR activation. Thus, endogenous MHCI tonically inhibits NMDAR function and controls downstream NMDAR-induced AMPA receptor trafficking during the expression of plasticity.
Bimodal gene expression in noncooperative regulatory systems
Authors: Ochab-Marcinek Anna , Tabaka Marcin
Published: December 2010

Bimodality of gene expression, as a mechanism contributing to phenotypic diversity, enhances the survival of cells in a fluctuating environment. To date, the bimodal response of a gene regulatory system has been attributed to the cooperativity of transcription factor binding or to feedback loops. It has remained unclear whether noncooperative binding of transcription factors can give rise to bimodality in an open-loop system. We study a theoretical model of gene expression in a two-step cascade (a deterministically monostable system) in which the regulatory gene produces transcription factors that have a nonlinear effect on the activity of the target gene. We show that a unimodal distribution of transcription factors over the cell population can generate a bimodal steady-state output without cooperative transcription factor binding. We introduce a simple method of geometric construction that allows one to predict the onset of bimodality. The construction only involves the parameters of bursting of the regulatory gene and the dose–response curve of the target gene. Using this method, we show that the gene expression may switch between unimodal and bimodal as the concentration of inducers or corepressors is varied. These findings may explain the experimentally observed bimodal response of cascades consisting of a fluorescent protein reporter controlled by the tetracycline repressor. The geometric construction provides a useful tool for designing experiments and for interpretation of their results. Our findings may have important implications for understanding the strategies adopted by cell populations to survive in changing environments.
Development of atopic dermatitis-like skin disease from the chronic loss of epidermal caspase-8
Authors: Li Christopher , Lasse Samuel , Lee Pedro , Nakasaki Manando , Chen Shih-Wei , Yamasaki Kenshi , Gallo Richard L. , Jamora Colin
Published: December 2010

Atopic dermatitis is an inflammatory skin disease that affects approximately 20% of children worldwide. Left untreated, the barrier function of the skin is compromised, increasing susceptibility to dehydration and infection. Despite its prevalence, its multifactorial nature has complicated the unraveling of its etiology. We found that chronic loss of epidermal caspase-8 recapitulates many aspects of atopic dermatitis, including a spongiotic phenotype whereby intercellular adhesion between epidermal keratinocytes is disrupted, adversely affecting tissue architecture and function. Although spongiosis is generally thought to be secondary to edema, we found that suppression of matrix metalloproteinase-2 activity is sufficient to abrogate this defect. p38 MAPK induces matrix metalloproteinase-2 expression to cleave E-cadherin, which mediates keratinocyte cohesion in the epidermis. Thus, the conditional loss of caspase-8, which we previously found to mimic a wound response, can be used to gain insights into how these same wound-healing processes are commandeered in inflammatory skin diseases.
Neural correlates of cognitive dissonance and choice-induced preference change
Authors: Izuma Keise , Matsumoto Madoka , Murayama Kou , Samejima Kazuyuki , Sadato Norihiro , Matsumoto Kenji
Published: December 2010

According to many modern economic theories, actions simply reflect an individual's preferences, whereas a psychological phenomenon called “cognitive dissonance” claims that actions can also create preference. Cognitive dissonance theory states that after making a difficult choice between two equally preferred items, the act of rejecting a favorite item induces an uncomfortable feeling (cognitive dissonance), which in turn motivates individuals to change their preferences to match their prior decision (i.e., reducing preference for rejected items). Recently, however, Chen and Risen [Chen K, Risen J (2010)J Pers Soc Psychol99:573–594] pointed out a serious methodological problem, which casts a doubt on the very existence of this choice-induced preference change as studied over the past 50 y. Here, using a proper control condition and two measures of preferences (self-report and brain activity), we found that the mere act of making a choice can change self-report preference as well as its neural representation (i.e., striatum activity), thus providing strong evidence for choice-induced preference change. Furthermore, our data indicate that the anterior cingulate cortex and dorsolateral prefrontal cortex tracked the degree of cognitive dissonance on a trial-by-trial basis. Our findings provide important insights into the neural basis of how actions can alter an individual's preferences.
Opn5 is a UV-sensitive bistable pigment that couples with Gi subtype of G protein
Authors: Yamashita Takahiro , Ohuchi Hideyo , Tomonari Sayuri , Ikeda Keiko , Sakai Kazumi , Shichida Yoshinori
Published: December 2010

Opn5 (neuropsin) belongs to an independent group separated from the other six groups in the phylogenetic tree of opsins, for which little information of absorption characteristics and molecular properties of the members is available. Here we show that the chicken Opn5 (cOpn5m) is a UV-sensitive bistable pigment that couples with Gi subtype of G protein. The recombinant expression of cOpn5m in HEK 293s cells followed by the addition of 11-
cis
- and
all-trans
-retinal produced UV light-absorbing and visible light-absorbing forms, respectively. These forms were interconvertible by UV and visible light irradiations, respectively, indicating that cOpn5m is a bistable pigment. The absorption maxima of these forms were estimated to be 360 and 474 nm, respectively. The GTPγS binding assay clearly showed that the visible light-absorbing form having
all-trans
-retinal activates Gi type of G protein, whereas no Gt or Gq activation ability was observed. Immunohistochemical studies using an antibody against cOpn5m clearly showed that this pigment is localized within some types of amacrine cells and some cells in the ganglion cell layer of the retinas, the vast majority of cells in the pineal gland and serotonin-positive cells in the paraventricular organ. Because cOpn5m is the only UV-sensitive opsin among the opsins found so far in chicken, this study provides the molecular basis for UV reception in chicken.
Structural basis for effectiveness of siderophore-conjugated monocarbams against clinically relevant strains ofPseudomonas aeruginosa
Authors: Han Seungil , Zaniewski Richard P. , Marr Eric S. , Lacey Brian M. , Tomaras Andrew P. , Evdokimov Artem , Miller J. Richard , Shanmugasundaram Veerabahu
Published: December 2010

Pseudomonas aeruginosais an opportunistic Gram-negative pathogen that causes nosocomial infections for which there are limited treatment options. Penicillin-binding protein PBP3, a key therapeutic target, is an essential enzyme responsible for the final steps of peptidoglycan synthesis and is covalently inactivated by β-lactam antibiotics. Here we disclose the first high resolution cocrystal structures of theP. aeruginosaPBP3 with both novel and marketed β-lactams. These structures reveal a conformational rearrangement of Tyr532 and Phe533 and a ligand-induced conformational change of Tyr409 and Arg489. The well-known affinity of the monobactam aztreonam forP. aeruginosaPBP3 is due to a distinct hydrophobic aromatic wall composed of Tyr503, Tyr532, and Phe533 interacting with the gem-dimethyl group. The structure of MC-1, a new siderophore-conjugated monocarbam complexed with PBP3 provides molecular insights for lead optimization. Importantly, we have identified a novel conformation that is distinct to the high-molecular-weight class B PBP subfamily, which is identifiable by common features such as a hydrophobic aromatic wall formed by Tyr503, Tyr532, and Phe533 and the structural flexibility of Tyr409 flanked by two glycine residues. This is also the first example of a siderophore-conjugated triazolone-linked monocarbam complexed with any PBP. Energetic analysis of tightly and loosely held computed hydration sites indicates protein desolvation effects contribute significantly to PBP3 binding, and analysis of hydration site energies allows rank ordering of the second-order acylation rate constants. Taken together, these structural, biochemical, and computational studies provide a molecular basis for recognition ofP. aeruginosaPBP3 and open avenues for future design of inhibitors of this class of PBPs.
VGLUT2 expression in primary afferent neurons is essential for normal acute pain and injury-induced heat hypersensitivity
Authors: Scherrer Grégory , Low Sarah A. , Wang Xidao , Zhang Jie , Yamanaka Hiroki , Urban Rochelle , Solorzano Carlos , Harper Blaine , Hnasko Thomas S. , Edwards Robert H. , Basbaum Allan I.
Published: December 2010

Dorsal root ganglia (DRG) neurons, including the nociceptors that detect painful thermal, mechanical, and chemical stimuli, transmit information to spinal cord neurons via glutamatergic and peptidergic neurotransmitters. However, the specific contribution of glutamate to pain generated by distinct sensory modalities or injuries is not known. Here we generated mice in which the vesicular glutamate transporter 2 (VGLUT2) is ablated selectively from DRG neurons. We report that conditional knockout (cKO) of the
Slc17a6
gene encoding VGLUT2 from the great majority of nociceptors profoundly decreased VGLUT2 mRNA and protein in these neurons, and reduced firing of lamina I spinal cord neurons in response to noxious heat and mechanical stimulation. In behavioral assays, cKO mice showed decreased responsiveness to acute noxious heat, mechanical, and chemical (capsaicin) stimuli, but responded normally to cold stimulation and in the formalin test. Strikingly, although tissue injury-induced heat hyperalgesia was lost in the cKO mice, mechanical hypersensitivity developed normally. In a model of nerve injury-induced neuropathic pain, the magnitude of heat hypersensitivity was diminished in cKO mice, but both the mechanical allodynia and the microgliosis generated by nerve injury were intact. These findings suggest that VGLUT2 expression in nociceptors is essential for normal perception of acute pain and heat hyperalgesia, and that heat and mechanical hypersensitivity induced by peripheral injury rely on distinct (VGLUT2 dependent and VGLUT2 independent, respectively) primary afferent mechanisms and pathways.
Synaptic targeting of AMPA receptors is regulated by a CaMKII site in the first intracellular loop of GluA1
Authors: Lu Wei , Isozaki Kaname , Roche Katherine W. , Nicoll Roger A.
Published: December 2010

The accumulation of AMPA receptors (AMPARs) at synapses is essential for excitatory synaptic transmission. However, the mechanisms underlying synaptic targeting of AMPARs remain elusive. We have now used a molecular replacement approach on an AMPAR-null background to investigate the targeting mechanisms necessary for regulating AMPAR trafficking in the hippocampus. Although there is an extensive literature on the role of the GluA1 C-tail in AMPAR trafficking, there is no effect of overexpressing the C-tail on basal transmission. Instead, we found that the first intracellular loop domain (Loop1) of GluA1, a previously overlooked region within AMPARs, is critical for receptor targeting to synapses, but not for delivery of receptors to the plasma membrane. We also identified a CaMKII phosphorylation site (S567) in the GluA1 Loop1, which is phosphorylated in vitro and in vivo. Furthermore, we show that S567 is a key residue that regulates Loop1-mediated AMPAR trafficking. Thus, our study reveals a unique mechanism for targeting AMPARs to synapses to mediate synaptic transmission.
Imaging T-cell receptor activation reveals accumulation of tyrosine-phosphorylated CD3ζ in the endosomal compartment
Authors: Yudushkin Ivan A. , Vale Ronald D.
Published: December 2010

Phosphorylation of the T-cell receptor complex (TcR/CD3) mediates the survival and antigen-induced activation of T cells. TcR/CD3 phosphorylation is usually monitored using phospho-specific antibodies, which precludes dynamic measurements. Here, we have developed genetically encoded, live-cell reporters that enable simultaneous monitoring of the phosphorylation state and intracellular trafficking of CD3ζ, the major signal-transducing subunit of the TcR/CD3. We show that these reporters provide accurate readouts of TcR/CD3 phosphorylation and are sensitive to the local balance of kinase and phosphatase activities acting upon TcR/CD3. Using these reporters, we demonstrate that, in addition to the expected activation-dependent phosphorylation at the plasma membrane, tyrosine-phosphorylated CD3ζ accumulates on endosomal vesicles distinct from lysosomes. These results suggest that an intracellular pool of phosphorylated CD3ζ may help to sustain TcR/CD3 signaling after the receptor internalization.