Understanding Cr segregation at the He bubble surface in Fe

Although Cr segregation at the free Fe surface is weak, noticeable segregation of Cr at the He bubble surface in Fe has recently been observed. To understand the driving force for Cr segregation, we have carried out first-principles density functional theory calculations on the energetics of solute Cr atoms at the He bubble surface, which was modeled by a Fe/He interface. We find that both the compressive stress produced by the He bubble and the direct interfacial interaction promote Cr segregation from inside the bulk to the bubble surface, along with reduced spin polarization. Electronic structure analyses show that at the Fe/He interface, Cr is more compressible than Fe due to having more empty e(g) orbitals and, accordingly, the Fe surface gets energetically more favorable for Cr than in the bulk. On the other hand, the segregation of Cr increases the charge density at the bubble surface, and thus hinders assimilation of further He atoms.

Human exposure from dioxins in soil

Dioxins are a family of chemical compounds that has received considerable attention, both historically and currently. This article reviews scientific field studies that examine the relationship between living on soil contaminated with dioxins and the level of dioxins in people's serum, with an emphasis on the University of Michigan Dioxin Exposure Study (UMDES), the largest and most comprehensive study of its kind. These studies conclude that the levels of dioxins in serum are most strongly correlated with age, gender, body mass index, weight loss, breast feeding, and smoking. Levels of dioxins in soil are not significant predictors for dioxin concentrations in serum. The increase in serum dioxin levels that is seen with age results from historic exposure and does not represent ongoing exposure. Based on the scientific field studies conducted to date, it appears that, in the absence of the consumption of contaminated animal products, there is little evidence of ongoing exposure from contaminated soil.

Effect of alloying additions on the hydrogen-induced grain boundary embrittlement in iron

Using ab initio density functional theory calculations, we have investigated the influence of Mo, V and Pd on the H-induced grain boundary embrittlement in Fe. We find that, in the high impurity concentration systems, all of the three alloying elements facilitate H embrittlement at the Σ3 (111) [Formula: see text] grain boundary in Fe. The calculated binary effects of the H-X (X = Mo, V, Pd) couples are 0.063, 0.074 and 0.040 eV, respectively. On the other hand, in the large unit cell with low impurity concentration, both Mo and V can facilitate H embrittlement, and the binary effects of pairs are 0.152 and 0.164 eV, respectively. While Pd reduces the H embrittlement on the cohesion of the Fe grain boundary with the binary effect of - 0.1 eV. The H-X (X = Mo, V, Pd) interactions are interpreted by electronic structure analyses.

Foliar Blight of Annual Vinca (Catharanthus roseus) Caused by Phytophthora tropicalis in Virginia

Annual vinca (Catharanthus roseus), also known as Madagascar periwinkle, has been cultivated as a major color crop for landscape and as an herbal medicine. This plant performs well in dry, warm locations with full sun or partial shade. Two-month-old diseased plants (cv. First Kiss Blueberry) with blighted leaves and stems were received from a local nursery in Suffolk, VA in May 2009. The disease began with dark, greenish black lesions on young leaves. Lesions gradually became tan or brown and leaves wilted and curled and finally turned necrotic. Brown, sunken lesions beginning at the branching points were typical symptoms on blighted stems and shoots. Blighted areas and spots were approximately 30 to 90 mm long and 20 to 40 mm wide on leaves and 40 mm long on stems. A Phytophthora species previously unknown to attack this plant was consistently isolated from diseased leaves and stems, and resultant isolates were grown on PARP-V8 agar. These isolates produced papillate sporangia on umbellate sympodium. Sporangia were mostly ellipsoid with a length/breadth ratio of >1.8 and tapered base; they were caducous with a long pedicel (usually >50 μm). These isolates also produced chlamydospores that averaged 31 μm in diameter. The isolates were identified as Phytophthora tropicalis by morphology. The identity was confirmed by DNA fingerprinting (1) and sequence analysis of ribosomal DNA internal transcribed spacers (GenBank Accession No. GQ478707). For pathogenicity studies, a zoospore suspension of 1,100 spores per milliliter was sprayed onto the foliage of 50-day-old healthy plants of the same cultivar grown in pine bark medium in six 10-cm-diameter plastic containers with a hand mister in the evening until runoff. Control plants were sprayed with tap water. Plants were placed in a tray containing a small amount of water and enclosed in plastic tents overnight to facilitate infection. The tents were removed the following morning, and plants were kept in a greenhouse under natural light and watered as needed. Within 4 days, all six inoculated plants developed foliar symptoms similar to what was observed on the diseased plant samples from the production nursery. The pathogen was reisolated from infected leaves and stems and its identity was confirmed by colony PCR-single-strand conformation polymorphism (3). The pathogenicity test was repeated once with the same results. Phytophthora aerial blight is a common destructive disease of annual vinca, which is usually caused by P. nicotianae. To our knowledge, this is the first report of foliar blight caused by P. tropicalis on annual vinca in Virginia. According to the head grower who submitted the disease samples, this new disease caused 10% crop loss of annual vinca this past spring. P. tropicalis was previously reported to attack ornamental shrubs, including Pieris japonica and Rhododendron catawbiense (2). This study indicates that P. tropicalis could be a potential threat to herbaceous annual crops as well. References: (1) M. E. Gallegly and C. X. Hong. Phytophthora: Identifying Species by Morphology and DNA Fingerprints. The American Phytopathological Society, St. Paul, MN, 2008. (2) C. Hong et al. Plant Dis. 90:525, 2006. (3) P. Kong et al. J. Microbiol. Methods 61:25, 2005.

Smad7 gene transfer inhibits peritoneal fibrosis

Fibrosis mediated by transforming growth factor-beta (TGF-beta) is a common cause of peritoneal dialysis (PD) failure. In a model of peritoneal fibrosis, we tested the effect of Smad7, an inhibitor of TGF-beta signaling, using an ultrasound-microbubble-mediated delivery system. Rats were given daily PD for 4 weeks and received Smad7 or control plasmid transfer. The ultrasound technique enhanced Smad7 expression in a dose-dependent manner in more than 80% of the peritoneal cells after 3 days. The expression decreased by 14 days, but this was corrected by a second gene transfer. The overexpression of Smad7 substantially inhibited Smad2/3 activation, TGF-beta, plasminogen activator inhibitor-1, extracellular matrix, and myofibroblast mRNA, and protein expression in the peritoneal cells. The decreased peritoneal injury included the rise of mass transfer of glucose, a reduction of the ultrafiltration rate, and fibrotic thickening. Our studies suggest that ultrasound-mediated Smad7 gene delivery may be useful in the prevention or treatment of dialysis-induced peritoneal fibrosis.

Innate immune receptor expression in normal brain aging

Brain aging often results in cognitive impairment and is considered to be a major risk factor for neurodegenerative diseases. Earlier studies reported inflammatory responses in aged brain that could contribute to age-related neurodegeneration. Recently, innate immune receptors such as toll-like receptors (TLRs), so far implicated in defense against microorganisms, have been linked to pathogenesis of Alzheimer's disease. Therefore, we asked whether the transcription of TLRs (1-9) and CD14, could also be altered in physiological brain aging. Using real-time polymerase chain reaction (PCR), we indeed observed that TLR1, TLR2, TLR4, TLR5, TLR7 and CD14 expression was up-regulated in mouse brain in correlation with age. In contrast, transcriptions of TLR3, TLR6 and TLR8 were unchanged and the one of TLR9 was down-regulated. In situ hybridization further confirmed these results and identified the cellular source of TLR2 and TLR7 as mononuclear phagocytes. Together, this first systematic analysis demonstrates altered regulation of those innate immune receptors even in normal brain aging, which might be of relevance for understanding susceptibility to neurodegenerative processes associated with aging.

An operational assessment of the application of the relative reduction factors in the demonstration of attainment of the 8-hr ozone National Ambient Air Quality Standard

The U.S. Environmental Protection Agency in 1997 revised the 1-hr ozone (O3) National Ambient Air Quality Standard (NAAQS) to one based on an 8-hr average, resulting in potential nonattainment status for substantial portions of the eastern United States. The regulatory process provides for the development of a state implementation plan that includes a demonstration that the projected future O3 concentrations will be at or below the NAAQS based on photochemical modeling and analytical techniques. In this study, four photochemical modeling systems, based on two photochemical models, Community Model for Air Quality and the Comprehensive Air Quality Model with extensions, and two emissions processing models, Sparse Matrix Optimization Kernel for Emissions and Emissions Modeling System, were applied to the eastern United States, with emphasis on the northeastern Ozone Transport Region in terms of their response to oxides of nitrogen and volatile organic carbon-focused controls on the estimated design values. With the 8-hr O3 NAAQS set as a bright-line test, it was found that a given area could be termed as being in or out of attainment of the NAAQS depending upon the modeling system. This suggests the need to provide an estimate of model-to-model uncertainty in the relative reduction factor (RRF) for a better understanding of the uncertainty in projecting the status of an area's attainment. Results indicate that the model-to-model differences considered in this study introduce

Biological denitrification in a sequencing batch reactor

Biological denitrification was studied in an SBR to investigate the performance. The experimental results showed that granular sludge with high activity and good settling ability can be developed smoothly in thereactor. With the granular sludge, high nitrate loading rate (0.48 kg NO3-N dm(-3) d(-1)) and removal efficiency (more than 99%) can be achieved. Scanning electronic microscope examination showed that only rod-shape bacteria existed on and within the granules, which confirmed indirectly that filamentous bacteria do not utilize nitrate and nitrite as electron acceptors. SBR is an alternative and effective technology for biological denitrification.

Upsilon production and polarization in p p macro collisions at square root of s = 1.8 TeV

We report on measurements of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) differential cross sections (d(2)sigma/dp(T)dy)(/y/<0.4), as well as on the Upsilon(1S) polarization in p p macro collisions at square root of s = 1.8 TeV using a sample of 77+/-3 pb(-1) collected by the collider detector at Fermilab. The three resonances were reconstructed through the decay Upsilon-->mu(+)mu(-). The measured angular distribution of the muons in the Upsilon(1S) rest frame is consistent with unpolarized meson production.

Diffractive dijet production at sqrt[s] = 630 and 1800 GeV at the Fermilab Tevatron

We report a measurement of the diffractive structure function F(D)(jj) of the antiproton obtained from a study of dijet events produced in association with a leading antiproton in pp collisions at sqrt[s] = 630 GeV at the Fermilab Tevatron. The ratio of F(D)(jj) at sqrt[s] = 630 GeV to F(D)(jj) obtained from a similar measurement at sqrt[s] = 1800 GeV is compared with expectations from QCD factorization and other theoretical predictions. We also report a measurement of the xi ( x-Pomeron) and beta ( x of parton in Pomeron) dependence of F(D)(jj) at sqrt[s] = 1800 GeV. In the region 0.035<xi<0.095, /t/<1 GeV2, and beta<0.5, F(D)(jj)(beta,xi) is found to be of the form beta(-1.0+/-0.1)xi(-0.9+/-0.1), which obeys beta-xi factorization.

Search for new heavy particles in the WZ0 final state in pp collisions at square root[s] = 1.8 TeV

We present the first general search for new heavy particles, X, which decay via X --> WZ0 --> e(nu)+jj as a function of M(X) and Gamma(X) in pp collisions at square root[s] = 1.8 TeV. No evidence is found for production of X in 110 pb(-1) of data collected by the Collider Detector at Fermilab. General cross section limits are set at the 95% C.L. as a function of mass and width of the new particle. The results are further interpreted as mass limits on the production of new heavy charged vector bosons which decay via W' --> WZ0 in an extended gauge model as a function of the width, Gamma(W'), and mixing factor between the W' and the standard model W bosons.

Study of B0 --> J/psiK(*)0pi(+)pi(-) decays with the collider detector at Fermilab

We report a study of the decays B0 --> J/psiK(*)0pi(+)pi(-), which involve the creation of a uu or dd quark pair in addition to a b -->c(cs) decay. The data sample consists of 110 pb(-1) of pp collisions at square root[s] = 1.8 TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992-1995. We measure the branching fractions to be B(B0 --> J/psiK(*0)pi(+)pi(-)) = (6.6 +/- 1.9 +/- 1.1)x10(-4) and B(B0 --> J/psiK0pi(+)pi(-)) = (10.3 +/- 3.3 +/- 1.5)x10(-4). Evidence is seen for contributions from psi(2S)K(*)0, J/psiK0rho(0), J/psiK(*+)pi(-), and J/psiK1(1270).

Search for gluinos and scalar quarks in pp collisions at square root[s] = 1.8 TeV using the missing energy plus multijets signature

We have performed a search for gluinos (g) and scalar quarks (q) in a data sample of 84 pb(-1) of pp collisions at square root[s] = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and three or more jets, a characteristic signature in R-parity-conserving supersymmetric models. The analysis has been performed "blind," in that the inspection of the signal region is made only after the predictions from standard model backgrounds have been calculated. Comparing the data with predictions of constrained supersymmetric models, we exclude gluino masses below 195 GeV/c2 (95% C.L.), independent of the squark mass. For the case m(q) approximately m(g), gluino masses below 300 GeV/c2 are excluded.

Measurement of the strong coupling constant from inclusive jet production at the Tevatron pp collider

We report a measurement of the strong coupling constant, alpha(s)(MZ), extracted from inclusive jet production in pp collisions at square root[s] = 1800 GeV. The QCD prediction for the evolution of alpha(s) with jet transverse energy ET is tested over the range 40<ET<450 GeV using ET for the renormalization scale. The data show good agreement with QCD in the region below 250 GeV. The value of alpha(s) at the mass of the Z0 boson averaged over the range 40<ET<250 GeV is found to be alpha(s)(MZ) = 0.1178+/-0.0001(stat)+0.0081(-0.0095)(expt. syst). The associated theoretical uncertainties are mainly due to the choice of renormalization scale ((+6%)(-4%)) and input parton distribution functions (5%).

Search for gluinos and squarks using like-sign dileptons in pp macro collisions at square root of s = 1.8 TeV

We present results of the first search for like-sign dilepton ( e(+/-)e(+/-), e(+/-)mu(+/-), mu(+/-)mu(+/-)) events associated with multijets and large missing energy using 106 pb(-1) of data in pp macro collisions at square root of s = 1.8 TeV collected during 1992-1995 by the CDF experiment. Finding no events that pass our selection, we examine pair production of gluinos (tilde g) and squarks (tilde q) in a constrained framework of the minimal supersymmetric standard model. At tan beta = 2 and mu = -800 GeV/c(2), we set 95% confidence level limits of M(tilde g)>221 GeV/c(2) for M(tilde g) approximately M(tilde q), and M(tilde q)>168 GeV/c(2) for M(tilde q)>>M(tilde g), both with small variation as a function of mu.

Observation of diffractive J/psi production at the Fermilab Tevatron

We report the first observation of diffractive J/psi(--> mu+mu-) production in pp collisions at root square[s] = 1.8 TeV. Diffractive events are identified by their rapidity gap signature. In a sample of events with two muons of transverse momentum p(mu)T>2 GeV/c within the pseudorapidity region /eta/ < 1.0, the ratio of diffractive to total J/psi production rates is found to be R(J/psi) = [1.45 +/- 0.25]%. The ratio R(J/psi)(x) is presented as a function of x-Bjorken. By combining it with our previously measured corresponding ratio R(jj)(x) for diffractive dijet production, we extract a value of 0.59 +/- 0.15 for the gluon fraction of the diffractive structure function of the proton.

Search for quark-lepton compositeness and a heavy W' Boson using the enu channel in p p macro collisions at square root of [s] = 1.8 TeV

We present searches for quark-lepton compositeness and a heavy W' boson at high electron-neutrino transverse mass. We use approximately 110 pb(-1) of data collected in p p macro collisions at square root of [s] = 1.8 TeV by the CDF Collaboration during 1992-1995. The data are consistent with standard model expectations. Limits are set on the quark-lepton compositeness scale Lambda, the ratio of partial cross sections sigma(W'-->enu)/sigma(W-->enu), and the mass of a W' boson with standard model couplings. We exclude Lambda<2.81 TeV and a W' boson with mass below 754 GeV/c(2) at the 95% confidence level. Combining with our previously published limit obtained using the muon channel, we exclude a W' boson with mass below 786 GeV/c(2) at the 95% confidence level.