bluuebunny/crossref_metadata_2025 huggingface dataset:
Proinflammatory T-cell responses to gut microbiota promote experimental autoimmune encephalomyelitis
Authors: Lee Yun Kyung , Menezes Juscilene S. , Umesaki Yoshinori , Mazmanian Sarkis K.
Published: July 2010

Although the effects of commensal bacteria on intestinal immune development seem to be profound, it remains speculative whether the gut microbiota influences extraintestinal biological functions. Multiple sclerosis (MS) is a devastating autoimmune disease leading to progressive deterioration of neurological function. Although the cause of MS is unknown, microorganisms seem to be important for the onset and/or progression of disease. However, it is unclear how microbial colonization, either symbiotic or infectious, affects autoimmunity. Herein, we investigate a role for the microbiota during the induction of experimental autoimmune encephalomyelitis (EAE), an animal model for MS. Mice maintained under germ-free conditions develop significantly attenuated EAE compared with conventionally colonized mice. Germ-free animals, induced for EAE, produce lower levels of the proinflammatory cytokines IFN-γ and IL-17A in both the intestine and spinal cord but display a reciprocal increase in CD4
+
CD25
+
Foxp3
+
regulatory T cells (Tregs). Mechanistically, we show that gut dendritic cells from germ-free animals are reduced in the ability to stimulate proinflammatory T cell responses. Intestinal colonization with segmented filamentous bacteria (SFB) is known to promote IL-17 production in the gut; here, we show that SFBs also induced IL-17A–producing CD4
+
T cells (Th17) in the CNS. Remarkably, germ-free animals harboring SFBs alone developed EAE, showing that gut bacteria can affect neurologic inflammation. These findings reveal that the intestinal microbiota profoundly impacts the balance between pro- and antiinflammatory immune responses during EAE and suggest that modulation of gut bacteria may provide therapeutic targets for extraintestinal inflammatory diseases such as MS.
Treating gout with pegloticase, a PEGylated urate oxidase, provides insight into the importance of uric acid as an antioxidant in vivo
Authors: Hershfield Michael S. , Roberts L. Jackson , Ganson Nancy J. , Kelly Susan J. , Santisteban Ines , Scarlett Edna , Jaggers Denise , Sundy John S.
Published: July 2010

A high plasma urate concentration (PUA), related to loss of urate oxidase in evolution, is postulated to protect humans from oxidative injury. This hypothesis has broad clinical relevance, but support rests largely on in vitro data and epidemiologic associations. Pegloticase therapy generates H
2
O
2
while depleting urate, offering an in vivo test of the antioxidant hypothesis. We show that erythrocytes can efficiently eliminate H
2
O
2
derived from urate oxidation to prevent cell injury in vitro; during therapy, disulfide-linked peroxiredoxin 2 dimer did not accumulate in red blood cells, indicating that their peroxidase capacity was not exceeded. To assess oxidative stress, we monitored F2-Isoprostanes (F2-IsoPs) and protein carbonyls (PC), products of arachidonic acid and protein oxidation, in plasma of 26 refractory gout patients receiving up to five infusions of pegloticase at 3-wk intervals. At baseline, PUA was markedly elevated in all patients, and plasma F2-IsoP concentration was elevated in most. Pegloticase infusion rapidly lowered mean PUA to ≤1 mg/dL in all patients, and PUA remained low in 16 of 21 patients who completed treatment. F2-IsoP levels did not correlate with PUA and did not increase during 15 wk of sustained urate depletion. There also was no significant change in the levels of plasma PC. Because refractory gout is associated with high oxidative stress in spite of high PUA, and profoundly depleting uric acid did not increase lipid or protein oxidation, we conclude that urate is not a major factor controlling oxidative stress in vivo.
Native bees mediate long-distance pollen dispersal in a shade coffee landscape mosaic
Authors: Jha Shalene , Dick Christopher W.
Published: July 2010

Coffee farms are often embedded within a mosaic of agriculture and forest fragments in the world's most biologically diverse tropical regions. Although shade coffee farms can potentially support native pollinator communities, the degree to which these pollinators facilitate gene flow for native trees is unknown. We examined the role of native bees as vectors of gene flow for a reproductively specialized native tree,
Miconia affinis
, in a shade coffee and remnant forest landscape mosaic. We demonstrate extensive cross-habitat gene flow by native bees, with pollination events spanning more than 1,800 m. Pollen was carried twice as far within shade coffee habitat as in nearby forest, and trees growing within shade coffee farms received pollen from a far greater number of sires than trees within remnant forest. The study shows that shade coffee habitats support specialized native pollinators that enhance the fecundity and genetic diversity of remnant native trees.
Native-sized recombinant spider silk protein produced in metabolically engineered
Escherichia coli
results in a strong fiber
Authors: Xia Xiao-Xia , Qian Zhi-Gang , Ki Chang Seok , Park Young Hwan , Kaplan David L. , Lee Sang Yup
Published: July 2010

Spider dragline silk is a remarkably strong fiber that makes it attractive for numerous applications. Much has thus been done to make similar fibers by biomimic spinning of recombinant dragline silk proteins. However, success is limited in part due to the inability to successfully express native-sized recombinant silk proteins (250–320 kDa). Here we show that a 284.9 kDa recombinant protein of the spider
Nephila clavipes
is produced and spun into a fiber displaying mechanical properties comparable to those of the native silk. The native-sized protein, predominantly rich in glycine (44.9%), was favorably expressed in metabolically engineered
Escherichia coli
within which the glycyl-tRNA pool was elevated. We also found that the recombinant proteins of lower molecular weight versions yielded inferior fiber properties. The results provide insight into evolution of silk protein size related to mechanical performance, and also clarify why spinning lower molecular weight proteins does not recapitulate the properties of native fibers. Furthermore, the silk expression, purification, and spinning platform established here should be useful for sustainable production of natural quality dragline silk, potentially enabling broader applications.
Notch and Egfr signaling act antagonistically to regulate germ-line stem cell niche formation in
Drosophila
male embryonic gonads
Authors: Kitadate Yu , Kobayashi Satoru
Published: July 2010

Germ-line stem cells (GSCs) are maintained by the somatic microenvironment, or GSC niche, which ensures that GSCs can both self-renew and produce functional gametes. However, it remains unclear how the proper niche size and location are regulated within the developing gonads. In the
Drosophila
testis, the hub cells that form the GSC niche are derived from a subset of somatic gonadal precursors (SGPs) in the anterior portion of the embryonic gonad. Here we show that Notch signaling induces hub differentiation. Notch is activated in almost all SGPs in the male embryonic gonad, but Epidermal growth factor receptor (Egfr) is activated in posterior SGPs to repress hub differentiation, thereby restricting the expansion of hub differentiation in the embryonic gonad. We further show that Egfr is activated in posterior SGPs by Spitz ligand secreted from primordial germ cells (PGCs), whereas the Notch ligand Serrate is expressed in SGPs. This suggests that varying the number of PGCs alters niche size. Indeed, a decrease in the number of PGCs causes ectopic hub differentiation, which consequently increases their opportunity to recruit PGCs as GSCs. When ectopic hub differentiation is repressed, the decreased number of PGCs fails to become GSCs. Thus, we propose that SGPs sense PGC number via signals from PGCs to SGPs that modulate niche size, and that this serves as a mechanism for securing GSCs.
Optimal population coding by noisy spiking neurons
Authors: Tkačik Gašper , Prentice Jason S. , Balasubramanian Vijay , Schneidman Elad
Published: July 2010

In retina and in cortical slice the collective response of spiking neural populations is well described by “maximum-entropy” models in which only pairs of neurons interact. We asked, how should such interactions be organized to maximize the amount of information represented in population responses? To this end, we extended the linear-nonlinear-Poisson model of single neural response to include pairwise interactions, yielding a stimulus-dependent, pairwise maximum-entropy model. We found that as we varied the noise level in single neurons and the distribution of network inputs, the optimal pairwise interactions smoothly interpolated to achieve network functions that are usually regarded as discrete—stimulus decorrelation, error correction, and independent encoding. These functions reflected a trade-off between efficient consumption of finite neural bandwidth and the use of redundancy to mitigate noise. Spontaneous activity in the optimal network reflected stimulus-induced activity patterns, and single-neuron response variability overestimated network noise. Our analysis suggests that rather than having a single coding principle hardwired in their architecture, networks in the brain should adapt their function to changing noise and stimulus correlations.
Live imaging of
Drosophila
imaginal disc development
Authors: Aldaz Silvia , Escudero Luis M. , Freeman Matthew
Published: July 2010

Live imaging has revolutionized the analysis of developmental biology over the last few years. The ability to track in real time the dynamic processes that occur at tissue and cellular levels gives a much clearer view of development, and allows greater temporal resolution, than is possible with fixed tissue.
Drosophila
imaginal discs are a particularly important model of many aspects of development, but their small size and location inside the larva and pupa has prevented live imaging techniques from extensively being used in their study. Here, we introduce the use of viscous culture medium to enable high resolution imaging of imaginal disc development. As a proof of principle, we have analyzed the transformation that occurs during metamorphosis of the wing imaginal disc into the mature wing and report several previously unobserved stages of this model of organogenesis. These imaging methods are especially useful to study the complex and dynamic changes that occur during morphogenesis, but we show that they can also be used to analyze other developmental and cellular events. Moreover, our viscous medium creates a platform for future adaptation of other tissue culture conditions to allow imaging of a wide range of developmental events and systems.
Isolation of viable
Plasmodium falciparum
merozoites to define erythrocyte invasion events and advance vaccine and drug development
Authors: Boyle Michelle J. , Wilson Danny W. , Richards Jack S. , Riglar David T. , Tetteh Kevin K. A. , Conway David J. , Ralph Stuart A. , Baum Jake , Beeson James G.
Published: July 2010

During blood-stage infection by
Plasmodium falciparum,
merozoites invade RBCs. Currently there is limited knowledge of cellular and molecular invasion events, and no established assays are available to readily measure and quantify invasion-inhibitory antibodies or compounds for vaccine and drug studies. We report the isolation of viable merozoites that retain their invasive capacity, at high purity and yield, purified by filtration of highly synchronous populations of schizonts. We show that the half-life of merozoite invasive capacity after rupture is 5 min at 37 °C, and 15 min at room temperature. Studying the kinetics of invasion revealed that 80% of invasion events occur within 10 min of mixing merozoites and RBCs. Invasion efficiency was maximum at low merozoite-to-RBC ratios and occurred efficiently in the absence of serum and with high concentrations of dialyzed nonimmune serum. We developed and optimized an invasion assay by using purified merozoites that enabled invasion-inhibitory activity of antibodies and compounds to be measured separately from other mechanisms of growth inhibition; the assay was more sensitive for detecting inhibitory activity than established growth-inhibition assays. Furthermore, with the use of purified merozoites it was possible to capture and fix merozoites at different stages of invasion for visualization by immunofluorescence microscopy and EM. We thereby demonstrate that processing of the major merozoite antigen merozoite surface protein-1 occurs at the time of RBC invasion. These findings have important implications for defining invasion events and molecular interactions, understanding immune interactions, and identifying and evaluating inhibitors to advance vaccine and drug development.
Structure of a C-terminal fragment of its Vps53 subunit suggests similarity of Golgi-associated retrograde protein (GARP) complex to a family of tethering complexes
Authors: Vasan Neil , Hutagalung Alex , Novick Peter , Reinisch Karin M.
Published: July 2010

The Golgi-associated retrograde protein (GARP) complex is a membrane-tethering complex that functions in traffic from endosomes to the trans-Golgi network. Here we present the structure of a C-terminal fragment of the Vps53 subunit, important for binding endosome-derived vesicles, at a resolution of 2.9 Å. We show that the C terminus consists of two α-helical bundles arranged in tandem, and we identify a highly conserved surface patch, which may play a role in vesicle recognition. Mutations of the surface result in defects in membrane traffic. The fold of the Vps53 C terminus is strongly reminiscent of proteins that belong to three other tethering complexes—Dsl1, conserved oligomeric Golgi, and the exocyst—thought to share a common evolutionary origin. Thus, the structure of the Vps53 C terminus suggests that GARP belongs to this family of complexes.
Myocytic androgen receptor controls the strength but not the mass of limb muscles
Authors: Chambon Céline , Duteil Delphine , Vignaud Alban , Ferry Arnaud , Messaddeq Nadia , Malivindi Rocco , Kato Shigeaki , Chambon Pierre , Metzger Daniel
Published: July 2010

The anabolic effects of androgens on skeletal muscles are thought to be mediated predominantly through the androgen receptor (AR), a member of the ligand-dependent nuclear receptor superfamily. However, despite numerous studies performed in men and in rodents, these effects remain poorly understood. To characterize androgen signaling in skeletal muscles, we generated mice in which the AR is selectively ablated in myofibers. We show that myocytic AR controls androgen-induced insulin-like growth factor IEa (IGF-IEa) expression in the highly androgen-sensitive perineal muscles and that it mediates androgen-stimulated postnatal hypertrophy of these muscles. In contrast, androgen-dependent postnatal hypertrophy of limb muscle fibers is independent of myocytic AR. Thus, androgens control perineal and limb muscle mass in male mice through myocytic AR-dependent and -independent pathways, respectively. Importantly, we also show that AR deficiency in limb myocytes impairs myofibrillar organization of sarcomeres and decreases muscle strength, thus demonstrating that myocytic AR controls key pathways required for maximum force production. These distinct androgen signaling pathways in perineal and limb muscles may allow the design of screens to identify selective androgen modulators of muscle strength.
Polybromo-associated BRG1-associated factor components BRD7 and BAF180 are critical regulators of p53 required for induction of replicative senescence
Authors: Burrows Anna E. , Smogorzewska Agata , Elledge Stephen J.
Published: July 2010

A variety of tumor-suppressor mechanisms exist to promote genome integrity and organismal survival. One such mechanism is cellular senescence. In response to replicative aging, DNA damage, and oncogenic stimuli, the p53 and Rb pathways are activated to prevent the proliferation of damaged cells by inducing senescence or apoptosis. We have performed a loss-of-function genetic screen in primary human cells to identify components of the senescence machinery. Here we describe BRD7 and BAF180 as unique regulators of replicative senescence in human cells. Both regulate p53 transcriptional activity toward a subset of its target genes required for replicative and oncogenic stress senescence induction, and BRD7 physically interacts with p53. BRD7 is a deletion target in human cancer, suggesting that loss of BRD7 may provide an additional mechanism to antagonize p53 function in cancer cells.
CAPITALIST WELFARE SOCIETIES' TRADE-OFF BETWEEN ECONOMIC EFFICIENCY AND SOCIAL SOLIDARITY
Authors: Frericks Patricia
Published: July 2010

Starting in the 1980s and 1990s, in various European welfare reforms, parts of the social insurance systems and the related resources were transferred to the financial market. In this sense, one can speak of privatisation and marketisation, both examples of a neo-liberal tendency. Now, after ‘the Fall of Finance Capitalism’, it is often stated that ‘the years of neoliberal triumph have come to an end’. This paper argues that there had already been a contrasting and powerful development previously, which might now be reinforced. This political and institutional development was moving towards extensive regulatory policies, in particular after the stock market crisis in 2001, and towards solidarity, two examples of a neo-etatistic tendency. I argue that the traditional exclusionary categorisation significantly underestimates the continuously changing mix. I will introduce a more complex approach which will be much more helpful to comprehend current developments in pension protection, and which might also be considered for providing an understanding of change in social protection schemes and welfare states in general. To my view, current changes in capitalist welfare societies are system-inherent substantiations of complexly intertwined dynamics, which can be comprehended by analysing changes in flows of resources and in the rights over these resources. These changes are manifest in what is termed social citizenship. Consequently, I will come to the conclusion that the observed changes promote new forms of social citizenship.
Anaplasma phagocytophilum induces actin phosphorylation to selectively regulate gene transcription in Ixodes scapularis ticks
Authors: Sultana Hameeda , Neelakanta Girish , Kantor Fred S. , Malawista Stephen E. , Fish Durland , Montgomery Ruth R. , Fikrig Erol
Published: July 2010

Anaplasma phagocytophilum, the agent of human anaplasmosis, persists in ticks and mammals. We show that A. phagocytophilum induces the phosphorylation of actin in an Ixodes ricinus tick cell line and Ixodes scapularis ticks, to alter the ratio of monomeric/filamentous (G/F) actin. A. phagocytophilum–induced actin phosphorylation was dependent on Ixodes p21-activated kinase (IPAK1)–mediated signaling. A. phagocytophilum stimulated IPAK1 activity via the G protein–coupled receptor Gβγ subunits, which mediated phosphoinositide 3-kinase (PI3K) activation. Disruption of Ixodes gβγ, pi3k, and pak1 reduced actin phosphorylation and bacterial acquisition by ticks. A. phagocytophilum–induced actin phosphorylation resulted in increased nuclear G actin and phosphorylated actin. The latter, in association with RNA polymerase II (RNAPII), enhanced binding of TATA box–binding protein to RNAPII and selectively promoted expression of salp16, a gene crucial for A. phagocytophilum survival. These data define a mechanism that A. phagocytophilum uses to selectively alter arthropod gene expression for its benefit and suggest new strategies to interfere with the life cycle of this intracellular pathogen, and perhaps other Rickettsia-related microbes of medical importance.
B-XandC-XBand Systems of CuCl Revisited: Laser-induced Fluorescence Study in 465–490 nm
Authors: Wang Li , Zhen Jun-feng , Zhang Qun , Chen Yang
Published: July 2010

We have reinvestigated the B-X and C-X band systems of CuCl by recording the laser-induced fluorescence excitation spectra in 20400–21800 cm−1. The rotational analyses in Hund's case (a) revealed unambiguously a singlet-to-singlet transition nature. The radiative lifetimes were measured to be 4.670 and 4.667 μs, respectively, which are much longer than that expected for a pure singlet of CuCl. This implies that the fluorescence mechanism in the B or C band systems lies in the mixing of the singlets (1Π and 1σ+) and triplets (3Π0,1,2) and that the two excited states observed in our experiment might be the singlets that have been strongly “contaminated" by their triplet neighbors.
Influence Factors on Particle Growth for On-line Aerosol Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry
Authors: Xia Wei-wei , Ti Ru-fang , Zhang Zi-Iiang , Zheng Hai-yang , Fang Li
Published: July 2010

An evaporation/condensation flow cell was developed and interfaced with the matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometer for on-line bioaerosol detection and characterization, which allows matrix addition by condensation onto the laboratory-generated bioaerosol particles. The final coated particle exiting from the condenser is then introduced into the aerodynamic particle sizer spectrometer or home-built aerosol laser time-of-flight mass spectrometer, and its aerodynamic size directly effects on the matrix-to-analyte molar ratio, which is very important for MALDI technique. In order to observe the protonated analyte molecular ion, and then determine the classification of biological aerosols, the matrix-to-analyte molar ratio must be appropriate. Four experimental parameters, including the temperature of the heated reservoir, the initial particle size, its number concentration, and the matrix material, were tested experimentally to analyze their influences on the final particle size. This technique represents an on-line system of detection that has the potential to provide rapid and reliable identification of airborne biological aerosols.
Dissipative Particle Dynamics Simulation of Microscopic Properties in Diblock Copolymer Films
Authors: Xu Yi , Song Xiao-yu , Zhang Zhang , Wang Yong , Chen Jie , Zhu Xian
Published: July 2010

Mean-square bond length, root-mean-square end-to-end distance and gyration radius in diblock copolymer films have been studied by dissipative particle dynamics simulations. Results show evident linear trends of any property separately with the thickness of film, the interaction between particles of different types, the repulsion between particle and boundary, except for the dependence of the variations of mean-square bond length on the thickness of film, which exhibits as a wave trend. What's more, the varying trends of mean-square bond length and root-mean-square end-to-end distance can correspond to each other. The density distribution of either component in diblock copolymer film can be controlled and adjusted effectively through its interaction with boundary.
Saturation Magnetization and Law of Approach to Saturation for Self-formed Ionic Ferrofluids Based on MnFe2O4 Nanoparticles
Authors: Lin Yue-qiang , Li Jian , Liu Xiao-dong , Zhang Ting-zhen , Wen Bang-cai , Zhang Qing-mei , Miao Hua
Published: July 2010

The magnetization curves of MnFe2O4 nanoparticles and self-formed ferrofluids based on these particles have been measured at room temperature. The median size of the particles is 13.67 nm. The specific saturation magnetization is less than the theoretical value for the ferrofluids. In the high field range from 5 kOe to 10 kOe, the higher the particle volume fraction is, the steeper the slope of the magnetization curves is when it approaches saturation. The behavior of the saturation magnetization and the law of approach to saturation are due to the presence of self-assembled aggregates of ring-like micelle structures which form in the absence of the magnetic field and field-induced aggregates, respectively. The field-induced aggregates have a dissipative structure, so that at high field, the law of approach to saturation magnetization is different from the one described using Langevin paramagnetism theory. The large particles in the ferrofluids result in apparent hysteresis.
Structural Characterization and Thermal Properties of 1-Amino-1-ethylamino-2,2-dinitroethylene
Authors: Xu Kang-zhen , Zhao Feng-qi , Wang Feng , Wang Han , Luo Jin-an , Hu Rong-zu
Published: July 2010

1-amino-1-ethylamino-2,2-dinitroethylene (AEFOX-7) was synthesized by the reaction of 1,1-diamino-2,2-dinitroethylene (FOX-7) and ethylamine aqueous solution at 92 °C. The theoretical investigation on AEFOX-7 was carried out by B3LYP/6–311++G** method. The IR frequencies and NMR chemical shifts were performed and compared with the experimental results. The thermal behavior of AEFOX-7 was studied with differential scanning calorimetry and thermal gravity-derivative thermogravimetry methods, and can be divided into a melting process and an exothermic decomposition process. The enthalpy, apparent activation energy and pre-exponential factor of the exothermic decomposition reaction were obtained as 374.88 kJ/mol, 169.7 kJ/mol, and 1019.24 s−1, respectively. The critical temperature of thermal explosion of AEFOX-7 is 145.2 °C. The specific heat capacity of AEFOX-7 was determined with micro-DSC method and theoretical calculation method, and the molar heat capacity is 214.50 J/(mol K) at 298.15 K. The adiabatic time-to-explosion of AEFOX-7 was calculated to be a certain value between 1.38–1.40 s. The thermal stability of AEFOX-7 is much lower than that of FOX-7.
Orientation in Nematic Liquid Crystals Doped with Orange Dyes and Effect of Carbon Nanoparticles
Authors: Alicilar Ahmet , Akkurt Fatih , Kaya Nihan
Published: July 2010

Some properties of nematic liquid crystal E7 doped with two disperse orange dyes used together and effect of addition of carbon nanoparticles (single walled carbon nanotube or fullerene C60) on them were studied. Two dyes (disperse orange 11 and 13) having high solubility and order parameter were used as co-dopants. A notable increase in order parameter was obtained comparing to that of liquid crystal doped with single dye. When carbon nanoparticles were used as dopant, a decrease in order parameter was observed at low temperatures while it increased at high temperatures. When applied voltage changed, the order parameter abruptly increased in its threshold value and saturated in higher voltages as expected. An appreciable change in textures was not observed with addition of dopants. This addition gave rise to an increase in nematic-isotropic phase transition temperatures compared with that of pure liquid crystal.
Effect of Simultaneous Addition of BiFeO3 and Ba(Cu0.5W0.5)O3 on Lowering of Sintering Temperature of Pb(Zr,Ti)O3 Ceramics
Authors: Kaneko Shoji , Dong Dunzhuo , Murakami Kenji
Published: July 2010

Sintering of 0.5‐wt%‐MnO2‐added Pb(Zr0.53Ti0.47)O3 ceramics progresses at 935°C for 50 min by the addition of complex oxides of perovskite‐type crystal structure, BiFeO3 and Ba(Cu0.5W0.5)O3. In order to elucidate the low‐temperature sintering mechanism of Pb(Zr,Ti)O3 ceramics, the shrinkage and the evolution of the microstructure of a compacted body during heating were studied. It has been shown that the densification process was separated into the following three stages: the rearrangement of grains, the grain boundary diffusion of atoms, and then grain growth. Also, microstructural and elemental analyses of the ceramics revealed the existence of an amorphous phase at the grain boundaries predominantly composed of lead and copper oxides. Consequently, this process can be facilitated by the occurrence of a transient liquid phase corresponding to the above amorphous phase.
Partial Stabilization of Tetragonal Zirconia in Oxynitride Glass‐Ceramics
Authors: Höche Thomas , Deckwerth Martin , Rüssel Christian
Published: July 2010

Nitrogen (via a polymeric AlN precursor) and ZrO2 are introduced into a MgO‐CaO‐Al2O3‐SiO2‐glass. Subsequent crystallization of the glass results in a fine‐grained oxynitride glass‐ceramic. The microstructure of the latter is found to be entirely different for nitrogen concentrations of 4.85 and 9.94 mol%. Not only do the phase contents differ, but also tetragonal zirconia is more effectively stabilized at higher nitrogen concentrations. Partial stabilization of tetragonal zirconia is not due to nitrogen incorporation but is based on an indirect effect: the spherical morphology of tetragonal zirconia precipitated at higher nitrogen contents suppresses the nucleation of the martensitic transformation. The beneficial effects of the introduction of nitrogen and the simultaneous incorporation of zirconia into a glass‐ceramic result in overall improved mechanical properties.
Phase Separation and Structural Differences between Alkali Silicate Glasses Prepared by the Sol‐Gel and Melt‐Quench Methods
Authors: Roy Biswanath , Jain Himanshu , Saha Shyamal K. , Chakravorty Dipankar
Published: July 2010

Glasses of composition xM2O:(1‐x)SiO2 [M = Na, Li] with x = 0.15 and 0.2 have been prepared both by the melt‐quench and the sol‐gel methods. X‐ray photoelectron spectroscopy shows that with increasing sintering temperature the structure of gels approaches that of the melt‐quench glass but does not become identical even on heating above the glass transition temperature (Tg). Phase separation occurs in gel much below Tg, and before it evolves into the structure of melt‐quench glass. Thus phase separation is achieved more readily in sintered gels than in the corresponding melt‐quench glass.
Some Remarks on “Improved Analysis for Flexural Creep with Application to SiAlON Ceramics”
Authors: Chuang Tze‐Jer
Published: July 2010

An earlier paper co‐authored by the present author contains a major assumption in the analytical method that may not be valid in a general class of structural ceramics. A more‐rigorous mathematical analysis without this assumption has been performed, and the closed‐form solutions of the description of the asymmetric power‐law creep behavior are presented. The results presented here should be regarded as further improvements to the original paper, because they are applicable to a more‐general case without such an assumption. Using the two loading cases as a numerical example, the present solutions indicate that, in the case of SiAlON ceramics, the original predictions on the stress exponents are still valid. However, the predictions on the pre‐exponent constants differ from one to three orders of magnitude, because of error propagation.
Improvements in the X‐ray Characteristics of Gd2O2S:Pr Ceramic Scintillators
Authors: Nakamura Ryouhei
Published: July 2010

The image quality of X‐ray computed tomography can be improved by using X‐ray detectors with more‐sensitive, low‐afterglow scintillators. A Gd2O2S:Pr ceramic scintillator with a light output 1.8 times that of CdWO4 already is available commercially to fit that need. The present study investigates the effect of adding various rare‐earth elements to Gd2O2S:Pr ceramic scintillators to improve light output and reduce radiation damage. When terbium is added in a 0.001 atomic fraction, light output improves ∼15%, based on energy transfer. Radiation damage decreases with increasing additions of cerium; the Ce3+ ions apparently reduce the color centers generated by X‐ray irradiation.
Spectroscopic Properties and Laser Performance Assessment of Yb3+ in Borophosphate Glasses
Authors: Feng Xian , Qi Changhong , Lin Fengying , Hu Hefang
Published: July 2010

Absorption and emission properties of Yb3+ in borophosphate glasses of the (55‐x)P2O5·xB2O3·10ZnO·10BaO·20SrO·5Nb2O5·1Yb2O3 series (x= 0, 11, 22, 33, 44, and 55) have been investigated. To avoid the problem arising from the radiation trapping effect, the reciprocity method is employed to calculate the emission cross section. It is found that the spectroscopic properties of Yb3+ in our borophosphate glasses are sensitive to the Yb3+ site environments. In addition, the laser performance of the Yb3+‐doped borophosphate glasses has been assessed. And the borophosphate glasses with values of x= 33 and 55 appear to be superior to the phosphate glasses as Yb‐grain media.
Properties of Modified Lead Zirconate Titanate Ceramics Prepared at Low Temperature (800°C) by Hot Isostatic Pressing
Authors: Li Jing‐Feng , Wang Shinan , Wakabayashi Katsuhiro , Esashi Masayoshi , Watanabe Ryuzo
Published: July 2010

High‐density lead zirconate titanate (PZT) ceramics were fabricated for the first time at a temperature as low as 800°C via the hot isostatic pressing (HIP) of a PZT powder with a modified composition of 0.92Pb(Zr0.53Ti0.47)O3—0.05BiFeO3—0.03Ba(Cu0.5W0.5)O3 that contained 0.5 mass% MnO2. The resultant PZT ceramics exhibited a microstructure that was denser and finer than that of PZT sintered at 935°C, which is the lowest temperature for the densification of the same composition via normal sintering. The relevant dielectric and piezoelectric properties of the HIPed PZT ceramics were as follows: coefficient of electromechanical coupling (K31), 31.8%; mechanical quality factor (Qm), 1364; piezoelectric constant (d31), −73.7 × 10−12 C/N; relative dielectric constant (ɛ33T/ɛ0), 633; dielectric loss factor (tan δ), 0.5%; Curie temperature (Tc), 285°C; and density (ρ), 8.06 g/cm3. In addition to these reasonably good piezoelectric properties, the HIPed PZT exhibited better mechanical properties—particularly, higher fracture strength—than the normally sintered PZT.
Effect of Sodium on Crystallite Size and Surface Area of Zirconia Powders at Elevated Temperatures
Authors: Chang Hsiao‐Lan , Shady Phillip , Shih Wei‐Heng
Published: July 2010

Fine ZrO2 powders were synthesized by an aqueous precipitation method using zirconyl nitrate. By adding the precursor salt to NaOH, single‐phase ZrO2 powders were formed, and the monoclinic phase did not appear upon heat treatment up to 1000°C. The samples were digested in NaOH for different amounts of time. Different levels of washing of digested samples produced surface area at 900°C for 4 h ranging from 8 to 100 m2/g. It was found that the properties of the powders at elevated temperatures were sensitive to the sodium content. The surface area decreased while the crystallite size and pore size of the samples increased with increased sodium content. Our results indicated that sodium is detrimental to the stabilization of surface area at elevated temperatures.
Structure of Liquid Al6Si2O13 (3:2 Mullite)
Authors: Krishnan Shankar , Weber J. Richard K. , Ansell Stuart , Hixson April D. , Nordine Paul C.
Published: July 2010

We report the first measurements of the structure factor, S(Q), and the pair distribution function, G(r), of Al6Si2O13 (3:2 mullite) in the normal and supercooled liquid states in the temperature range 1776–2203 K. Measurements are obtained by synchrotron X‐ray scattering on levitated, laser‐heated liquid specimens. The S(Q) shows a prepeak at 2.0 Å−1 followed by a main peak at 4.5 Å−1 and a weak feature at 8 Å−1. The G(r) shows a strong (Si,Al)–O correlation at 1.80 Å at high temperature that moves to 1.72 Å as the liquid is supercooled. The second and third nearest neighbor peaks at 3.0 and 4.25 Å sharpen with supercooling. The short‐range structure of the high‐temperature liquid is similar to the corresponding glasses produced by rapid quenching. Supercooling causes an increase in the concentration of tetrahedral Si4+ ions, which is manifested by the large shift in the first peak to lower ionic distance, r, values in G(r). The increase in tetrahedrally coordinated Si4+ ions is offset by an increase in octahedral Al3+ ions. The clustering of the SiO44− tetrahedral units results in increased viscosity of the liquid at temperatures below the melting point, which is consistent with Al6Si2O13 being a fragile liquid.
Atomistic Simulation of Dopant Incorporation in Barium Titanate
Authors: Buscaglia Maria Teresa , Buscaglia Vincenzo , Viviani Massimo , Nanni Paolo
Published: July 2010

The results of an atomistic simulation study on the incorporation of ions of the first series of transition metals (Cr3+, Cr4+, Fe2+, Fe3+, Co2+, Co3+, Ni2+, and Ni3+), Y3+, and ions of the lanthanide series (Er3+, Gd3+, Tb3+, Pr3+, Pr4+, and La3+) in the BaTiO3 lattice are presented and discussed. The ions of the transition metals prefer to substitute at the titanium site with oxygen‐vacancy compensation. For iron and cobalt, oxidation from the divalent to the trivalent state during incorporation is favored. Nickel and chromium are preferentially incorporated in the valence state 2+ and 3+, respectively. Formation of stable defect pairs with different types of lattice defects is predicted for the transition‐metal impurities. For La3+ and Pr3+, substitution occurs at the barium site, whereas Y3+, Tb3+, Gd3+, and Er3+ tend to simultaneous substitution on both cation sites. Formation of dopant–titanium‐vacancy pairs is predicted for the rare‐earth ions and Y3+. The effect of doping on the lattice parameter of c‐BaTiO3 has been studied by a mean‐field calculation. Comparison with experimental data confirms the dependence of the preferred substitution site on the ionic radius of the impurity. For dopants with intermediate size (Y3+, Er3+, Tb3+, and Gd3+), the Ba/Ti ratio is important in the incorporation mechanism.
Crack Growth along Interfaces in Porous Ceramic Layers
Authors: Sørensen Bent F. , Horsewell Andy
Published: July 2010

Crack growth along porous ceramic layers was studied experimentally. Double cantilever beam sandwich specimens were loaded with pure bending moments to obtain stable crack growth. The experiments were conducted in an environmental scanning electron microscope enabling in situ observations of various mechanisms associated with crack growth. The macroscopic fracture energy of the interface between dense lanthanum strontium chromite and a porous lanthanum strontium manganite was measured to lie in the range of 1.4–3.8 J/m2. Several micromechanisms were observed ahead of, or in the wake of, the crack tip. The measured variation of the fracture energy along the crack length may be attributed to such phenomena.
Filtration Behavior of Nanoparticulate Ceria Slurries
Authors: Dietrich Astrid , Neubrand Achim , Hirata Yoshihiro
Published: July 2010

The influence of poly(acrylic acid) (PAA) concentration and molecular weight on the filtration behavior of CeO2 slurries with 20 nm particle size was studied. Low‐viscosity suspensions could be produced by adsorbing a monolayer of PAA that covered the nanoparticles. For all suspensions investigated, the cake permeability was lower than predicted by the Kozeny–Carman equation and decreased with increased filtration pressure because of the presence of a compressible PAA layer 3–5 nm thick on the surface of the particles. The permeability of the nanoparticulate cakes decreased with increased polymer addition because of clogging.
ABCC11/MRP8 confers pemetrexed resistance in lung cancer
Authors: Uemura Takehiro , Oguri Tetsuya , Ozasa Hiroaki , Takakuwa Osamu , Miyazaki Mikinori , Maeno Ken , Sato Shigeki , Ueda Ryuzo
Published: July 2010

We have previously shown that overexpression of thymidylate synthetase (TS) resulted in pemetrexed (MTA) resistance. To investigate another mechanism of MTA resistance, we investigated the expression of ATP‐binding cassette (ABC)‐transporters in MTA‐resistant lung cancer cell lines and found that the gene and protein expression of ABCC11/MRP8 (ABCC11) was higher in MTA‐resistant cells than in the parental cells. The MTA resistant cells showed cross‐resistance to methotrexate (MTX), which is a substrate for ABCC11, and intracellular MTX accumulation in MTA‐resistant cells was lower than in the parental cells. We then tested the effect of decreasing the expression of ABCC11 by siRNA and found that decreased expression of ABCC11 enhanced MTA cytotoxicity and increased intracellular MTX accumulation in MTA‐resistant cells. These findings suggested that ABCC11 directly confers resistance to MTA by enhancing efflux of the intracellular anti‐cancer drug. Next, we analyzed the relationship between ABCC11 gene expression and MTA sensitivity of 13 adenocarcinoma cells, but there was no correlation. The ABCC11 gene has been shown to have a functional single‐nucleotide polymorphism (SNP), 538G>A. We then classified 13 lung adenocarcinoma cell lines into three groups based on the genotype of this ABCC11 SNP: G/G, G/A and A/A. The A/A group showed a significant reduction in the IC50 of MTA compared with the combined G/G and G/A groups, indicating that the SNP (538G>A) in the ABCC11 gene is an important determinant of MTA sensitivity. These results showed that ABCC11 may be one of the biomarkers for MTA treatment in adenocarcinomas. (Cancer Sci 2010; 101: 2404–2410)
A Cross‐matching Procedure for the Selection of Platelet Donors for Alloimmunized Patients
Authors: Waters A. H. , Minchinton R. M. , Bell R. , Ford J. M. , Lister T. A.
Published: July 2010

Summary. A platelet cross‐matching procedure has been assessed for selecting compatible donors for alloimmunized patients. This confirms the clinical value of combining an indirect platelet immunofluorescence test (PIFT) with a lymphocyto toxicity test (LCT) in predicting the survival of single‐donor platelets. There was good agreement between the PIFT cross‐match and post‐transfusion platelet recovery. Compatibility in the LCT alone was insufficient for platelet donor selection, as this test did not detect all antibodies affecting platelet survival.

Positive LCT and PIFT cross‐matches indicated the presence of HLA antibodies. Inclusion of an indirect lymphocyte immunofluorescence test (LIFT) helped to classify the platelet antibody when the LCT cross‐match was negative. In such cases, parallel positive findings with the LIFT and PIFT suggested a cytotoxic‐negative antibody of probable HLA specificity active against platelets. Disparity between the LIFT and PIFT was also observed; a strongly positive PIFT along with a weak reaction in the LIFT suggested that a platelet‐specific antibody was responsible for the poor platelet survival in these cases. This study has also shown the presence in multitransfused patients of LIFT‐positive antibodies not reacting in the LCT and PIFT, which do not affect the survival of transfused platelets.

A positive granulocyte cross‐match was demonstrated in patients with febrile rigors associated with compatible platelet transfusions. Splenectomy and steroids may improve the survival of incompatible platelets depending on the nature of the platelet antibody.
Erythroid Colony Growth in Vitro from Human Peripheral Blood Null Cells: Evidence for Regulation by T‐Lymphocytes and Monocytes
Authors: Reid C. D. L. , Baptista Luisa C. , Chanarin I.
Published: July 2010

Summary. Colony assays in methylcellulose of primitive erythroid precursors (BFU‐E) were carried out from the null cell fraction of normal human peripheral blood lymphoid cells. There was little proliferation or maturation of BFU‐E as assessed by both the number and the size of colonies formed, when null cells alone were cultured. Culture of null cells with up to 8 × 105 autologous T‐lymphocytes per ml led to considerable stimulation of colony growth and maturation. Culture of null cells with peripheral blood monocytes also resulted in the induction of BFU‐E growth, although the response was inferior to that seen with T‐cells. Co‐culture of null cells together with both T‐cells and monocytes resulted in a uniformly greater response than with either alone, and this was shown to be due to a positive interaction between these two cell types.
The direct antiglobulin test in P. falciparum malaria
Authors: Abdalla S. , Weatherall D. J.
Published: July 2010

Summary.

The direct antiglobulin test (DAT) was performed on 134 Gambian children with P. falciparum malaria. 52 children had a positive DAT and in 25 this was due to the adherence of C3 to their red cells whilst 13 had sensitization with IgG as well as C3. Sensitization with C4 alone or associated with IgG and/or C3 was only rarely found.
Fate of senescent megakaryocytes in the bone marrow
Authors: Radley J. M. , Haller C. J.
Published: July 2010

Summary. Degenerating senescent megakaryocytes have been identified in mouse bone marrow by light and electron microscopy. The ultrastructural changes which occur as degeneration proceeds are characteristic of death by apoptosis, although most cells appear to round up rather than undergo fragmentation. A hitherto unreported finding in degenerating cells was the presence of bundles of approximately 7 nm diameter parallel filaments in nuclei and membrane‐bound nuclear fragments. Structurally, they resembled bundles of filaments induced in nuclei with dimethyl sulphoxide and identified as actin. Often a bundle appeared to terminate at the inner membrane. In the cytoplasm the presence of microtubules and centrioles indicates that not all the latter organelles are lost by the megakaryocyte during platelet release. Degenerating senescent megakaryocytes are rare in the marrow of normal mice but increase in frequency during 5‐fluorouracil stimulated thrombocytosis. The dying cells are eventually phagocytosed by macrophages, a process that can occur extravascularly, showing that entry of senescent megakaryocytes into the circulation is not necessary for their disposal.
Effects of human marrow stromal cells on proliferation by human granulocytic (GM‐CFC), erythroid (BFU‐E) and mixed (Mix‐CFC) colony‐forming cells
Authors: Gordon M. Y. , Kearney L. , Hibbin J. A.
Published: July 2010

Summary. We have investigated the effects of the major components of bone marrow stroma (fibroblasts, fat cells, macrophages and endothelial cells) on colony‐forming haemopoietic precursor cells. Selective cultures of the different stromal cell types, grown to confluence, were used as underlayers for agar or methylcellulose cultures containing bone marrow cells. In different experiments, colony‐stimulating factor (CSF) was added to stimulated granulocyte‐macrophage colony‐forming cells (GM‐CFC), erythropoietin was used to induce erythroid burst (BFU‐E) formation or erythropoietin and medium conditioned by leucocytes in the presence of phytohae‐magglutinin (PHA‐LCM) was added to induce the formation of colonies of mixed myeloid lineage (Mix‐CFC)

Fibroblasts grown from human marrow enhanced granulopoiesis when CSF was present in the cultures but suppressed the formation of BFU‐E and mixed colonies. Treatment of the cultures with methylprednisolone induced the formation of fat cells in the fibroblast cultures and prevented both the fibroblast‐mediated enhancement of granulopoiesis and the fibroblast‐mediated suppression of erythropoiesis. Stromal macrophages reduced granulocyte colony formation but had little effect on the proliferation of BFU‐E or mixed colony‐forming cells. Endothelial cells stimulated granulopoiesis by releasing CSF into the culture supernatant: supernatant from endothelial cell cultures had no marked effects on either BFU‐E or Mix‐CFC.

We conclude that different components of marrow stroma have contrasting effects on erythropoiesis and granulopoiesis; thus, marrow stroma may regulate the expression of stem cell differentiation in vivo.